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Dissertation on
A STUDY ON THE EFFICACY OF HYPEROSMOTIC
CONTACT LENS IN THE TREATMENT OF CORNEAL
EDEMA
Submitted in partial fulfillment of requirements of
M.S. OPHTHALMOLOGY
BRANCH - III
REGIONAL INSTITUTE OF OPHTHALMOLOGY
MADRAS MEDICAL COLLEGE
CHENNAI- 600 003
THE TAMILNADU DR.M.G.R. MEDICAL
UNIVERSITY CHENNAI
MAY 2018
CERTIFICATE
This is to certify that this dissertation
entitled “A STUDY ON THE EFFICACY OF HYPEROSMOTIC
CONTACT LENS IN THE TREATMENT OF CORNEAL
EDEMA” is a bonafide record of the research work done by Dr. JIZ
MARY SANTHOSH, post graduate in Regional Institute of
Ophthalmology and Government Ophthalmic Hospital, Madras Medical
College and Government General Hospital, Chennai-03, in partial
fulfillment of the regulations laid down by The Tamil Nadu
Dr. M.G.R. Medical University for the award of M.S. Ophthalmology
Branch III, under my guidance and supervision during the academic
years 2015-2018.
Dr. R. NARAYANABABU M.D., D.Ch.,
Dean, Madras Medical College &
Government General Hospital, Chennai – 600 003.
DR.P.S.MAHESWARI M.S., D.O., Director and Superintendent(I/C), RIO – GOH, Egmore, Chennai – 600 008.
DR.M.ANANDA BABU M.S., D.O., Chief – CORNEA & CONTACT LENS SERVICES, RIO – GOH, Egmore, Chennai – 600 008.
ACKNOWLEDGEMENT
I express my sincere thanks and gratitude to
Dr. R. Narayanababu M.D., D.Ch., Dean, Madras Medical College
and Government General Hospital for permitting me to conduct this
study.
I express my sincere gratitude to Prof.Dr.P.S.MAHESWARI
M.S.,D.O., Director and Superintendent(I/C), Regional Institute of
Ophthalmology and Government Ophthalmic Hospital, Madras
Medical College, Chennai for her valuable advice in preparing this
dissertation and constant support at every stage throughout the period
of this study.
I am extremely grateful to Prof.Dr.M.ANANDABABU
M.S.,D.O., my Unit Chief for his valuable guidance and constant
support at every stage throughout the period of this study.
I am very grateful to my Assistant Professors
Dr.V.SHARMILA DEVI M.S., FAICO and Dr.B.MEENAKSHI
M.S.,D.O., for their valuable guidance and support not only during the
study but also throughout my course in all aspects.
I am grateful to my unit Assistant Professor Dr.M.SIVAKAMI
M.S., for rendering her constant support during the study period.
I am very grateful to Assistant Professor DR. K.S.T. LATHA,
M.S., Registrar, RIOGOH, for her guidance and encouragement.
I wish to express my sincere thanks to my father and mother and
to my Senior post graduates Dr. Akila and Dr.Prasanna, junior post
graduates and colleague Dr. S. Sivaviganesh, who had helped me in
bringing out this study. Finally I am indebted to all patients for their
sincere co-operation for completion of this study.
CERTIFICATE
This is to certify that this dissertation work titled “A STUDY ON
THE EFFICACY OF HYPEROSMOTIC CONTACT LENS IN
THE TREATMENT OF CORNEAL EDEMA” of the candidate
DR.JIZ MARY SANTHOSH with registration number 22513002 for
the award of MS in the branch of OPHTHALMOLOGY.
I personally verified the urkund.com website for the purpose of
plagiarism Check. I found that the uploaded thesis file contains from
introduction to conclusion pages and result shows 1% percentage of
plagiarism in the dissertation.
Guide & Supervisor sign with Seal
DECLARATION BY THE CANDIDATE
I hereby declare that this dissertation entitled “A STUDY ON
THE EFFICACY OF HYPEROSMOTIC CONTACT LENS IN
THE TREATMENT OF CORNEAL EDEMA” is a bonafide and
genuine research work carried out by me under the guidance of
Prof.Dr.M.ANANDA BABU.
DATE : DR.JIZ MARY SANTHOSH
PLACE:
CONTENTS
S.NO. TITLE PAGE NOS.
PART – I
1 INTRODUCTION 1
2 EMBRYONIC ORIGIN OF CORNEA 2
3 STRUCTURAL ANATOMY 3
4 CORNEAL NUTRITION AND METABOLISM 22
5 BLOOD SUPPLY OF CORNEA 23
6 NERVE SUPPLY OF CORNEA 24
7 CORNEAL TRANSPARENCY 25
8 CORNEAL EDEMA AND MANAGEMENT 32
9 THERAPEUTIC CONTACT LENS 44
10 HYPEROSMOTIC CONTACT LENS 54
PART – II
11 AIM AND OBJECTIVES 59
12 MATERIALS AND METHODS 60
13 OBSERVATION AND ANALYSIS 65
14 DISCUSSION 74
15 RESULTS 76
16 CONCLUSION 79
PART – III
17 PROFORMA
18 BIBLIOGRAPHY
19 MASTER CHART
20 KEY TO MASTER CHART
1
INTRODUCTION
Corneal edema is a common clinical finding in various
disorders in Ophthalmology. It can have numerous etiologies. Its
symptoms may range from mild to severe visual loss associated
with pain and extreme ocular discomfort. A good understanding of
the etiopathogenesis and current treatment modalities helps in the
management of this condition. Hyperosmotic contact lens is a
newer modality of treatment in managing corneal edema. This
study has been conducted to analyse the efficacy of hyperosmotic
contact lens in comparison to regular bandage contact lens in the
treatment of corneal edema.
2
CORNEA
Word cornea originated from Latin word-Cornu(horn).
EMBRYONIC ORIGIN OF CORNEA:
\
Figure 1 Human embryonic cornea
The formation of cornea is induced by the lens and the optic cup
at the 7th week of intrauterine life. [Fig 1]
Corneal epithelium – Surface ectoderm
Bowman’s membrane – Mesenchyme
Stroma – Mesenchyme and Neural crest
Descemet’s membrane – Synthesized by endothelium
Endothelium – Neural crest
3
STRUCTURAL ANATOMY
Cornea is structurally and functionally a highly efficient part
of the eye that provides a clear refractive surface, tensile strength
and protection from external factors.
It is a transparent, avascular tissue with a convex anterior
surface & concave posterior surface.
OPTICAL CHARACTERISTICS
1. Cornea is a clear transparent tissue comprising the central
one- sixth of outer tunic of the eye in continuity with sclera.
2. Cornea appears elliptical in shape measuring 11-12mm
horizontally and 10-11mm vertically with a surface area of
about 1.3 cm².
Radius of curvature: Anterior surface – about 7.8 mm
Posterior surface – about 6.5mm
3. Anterior surface refractive power is approximately +43.1 D.
4. Refractive index of the cornea : 1.376.
5. Cornea is prolate in shape with a thickness of about 540µm
centrally and more than 600µm peripherally.
6. The central one-third of cornea is called the optical zone and
measures about 5.4mm in diameter.
4
COMPOSITION OF HUMAN CORNEA
Water : 78 %
Collagen : 15 %
Type-I : 50-55 %
Type-III : 1 %
Type-IV : 8-10 %
Type-VI : 25-30 %
Other protein : 5 %
Keratan sulphate : 0.7 %
Condroitin/dermatan sulphate : 0.3 %
Hyaluronic acid : +
Salts : 1 %
LAYERS OF CORNEA
Beneath the pre-corneal tear film, there are six concentric
layers of cornea. [Fig 2]
5
Figure 2 Layers of human cornea
1. Epithelium.
2. Bowman’s layer ( anterior limiting lamina )
3. Stroma .
4. Dua’s layer.
5. Descemet’s membrane ( posterior limiting lamina)
6. Endothelium.
6
TEAR FILM
Figure 3 Structure of tear film
Provides a clear refractive interface for the cornea,
filling the depressions caused by the 0.5µm high micro
projections that emanate from the epithelial surface. The tear
film forms an important defence mechanism against the
microbial infection.
It is approximately 7µm thick with a volume of 6.5 ±
0.3µL and consists of:
Outer lipid layer 0.1µm thick- secreted by meibomian
gland secretion.
7
Middle aqueous layer(7µm)- secreted by the lacrimal
and accessory lacrimal gland.
Inner mucin layer 0.02 to 0.05µm- whose contents are
derived from the conjunctival goblet cells. [Fig 3]
EPITHELIUM
Figure 4(a) Layers of Epithelium
8
Figure 4 (b) Layers of epithelium
The corneal epithelium is stratified, squamous and non-
keratinized
It is continuous with the conjunctival epithelium at limbus
but having no goblet cells
It is about 50-90 μm in thickness. Consists of 5 or 6 layers of
nucleated cells resting on a basal lamina, namely [Fig 4 a,b]
a. Basal cells
b. Wing cells
c. Surface cells
9
Basal cells - Forms the deepest cell layer.
It stands in a palisade manner on the basal lamina.
It is the germinative layer of the epithelium and is
composed of columnar cells with rounded head and
flat base whose nucleus is oval and oriented parallel to
the cells long axis.
Wing Cells (umbrella cells) - Second epithelial cell layer (1-2
layers of cells)
They are polyhedral, convex anteriorly forming cap over
basal cells and send processes between them. Their nucleus is oval
and oriented parallel to corneal surface.
Surface cells - Most superficial 2-3 layers of cells. They are
polyhedral and become wider & flattened towards the surface.
They have flattened nuclei which project backwards leaving the
surface perfectly smooth .Most superficial cells are mostly
hexagonal in shape and exhibit surface microvilli or microplicae
coated with 300-nm thick glycocalyx/glycoprotein (buffy cell
coat).
10
Ultrastructural features:
Epithelial cells shows usual organelles like other actively
metabolizing cells.
Moderately abundant mitochondria in wing cells & middle
layer cells but small and scarce in basal cells.
Wing & superficial cells have high glycogen content.
Langerhans cells (cells of immune recognition system)
present near periphery. They are almost absent at central cornea but
aggregate in response to infection
Tonofibrils:
Cells contain a cytoplasmic meshwork of electrondense
intermediate filaments composed of cytokeratins.
The plasma membrane of contiguous cells interdigitative to
each other
Adhesion is achieved by –
Tight junctions & desmosomes – surface cells
Desmosomes – wings & superficial cells
Desmosomes & Hemidesmosomes – in basal cells.
11
BASAL LAMINA
Fibrous layer consisting of type IV collagen and
glycoprotein. It is secreted by the basal cells. The cells are 0.5 - 1
μm wide. Ultra structurally it is distinguished into two parts
1. Lamina lucida (superficial)- electron lucent zone
2. Lamina densa (deep electron dense zone).
It is anchored to the underlying Bowman’s layer with
numerous anchoring filaments
BOWMAN’S LAYER: (ANT. LIMITING LAMINA)
Figure 5 Bowman's membrane
12
It is an acellular homogeneous zone which is a modified
region of anterior stroma. The layer is 8 – 14μm thick. It is
perforated by many nerve axons which courses through toward the
epithelium. Its anterior surface is smooth & parallel with the
corneal surface, posteriorly it becomes blended and interweaved
with fibrils of anterior stroma. [Fig 5]
Ultrastructural features
It is an acellular meshwork of fine collagen fibrils of
uniform size in a ground substance (glycoprotein & proteoglycan).
It has compactly arranged collagen types I, III, V, and VI. It has
great strength, provides mechanical support and is relatively
resistant to trauma, both mechanical and infective. It lacks
fibroblast therefore after injury it is unable to regenerate and
replaced by scar tissue.
13
STROMA (SUBSTANTIA PROPRIA)
Figure 6 Corneal Stroma
About 500 μm thick. It forms about 90% of the corneal
thickness [Fig 6].It is transparent and rich in collagen-
predominantly of type I collagen with types III, V, and VI also.
The collagen fibers are interspersed in a proteoglycan
(glycosaminoglycan) ground substance. 5% of stromal volume is
occupied by keratocytes which synthesizes both collagen and
keratan sulfate.
Stroma ensures transparency of cornea by its unique lamellar
arrangement of collagen bundles.Stroma has about 200 layers of
lamellae. Each lamellae consists of 200 – 300 collagen bundles
14
centrally and 500 bundles peripherally. Width of Each bundle is
about 9 – 260 μm.Thickness about 1.15 – 2µm.
Arrangement of lamellae –
Figure 7 Arrangement of stromal lamellae
Lamellae are arranged in layers, parallel with each other &
with corneal surface. In deeper stroma the lamellae form strap-like
ribbons which run approximately at right angles to those in
consecutive layers[Fig 7]. At the periphery this right-angular
arrangement is slightly changed where it gets scleral fibres. At the
limbus the bundles appear to take a circular course
Ultrastructural features:
Each lamellae comprises of a band of collagen fibrils
arranged in parallel to each other with diameter of 22 nm. The
keratocytes occupy 2.5 – 5 % of total stromal volume and is
15
responsible for synthesis and maintaining of collagen &
proteoglycan substance of stroma.
Ground substances of stroma
The ground substance of cornea consists of proteoglycan
that run between the collagen fibers. It constitutes
approximately 10% of corneal weight proteoglycan are
glycosylated with glycosaminoglycan (GAGs)-disaccharides
GAGs include-
1. Keratin sulphate
2. Chondroitin sulphate
3. Dermatan sulphate
Function-
1. Confers hydrophilic properties of stroma
2. Maintains corneal transparency by controlled stromal
hydration by contributing fixed negative charge of stroma
(normally stroma is 78% hydrated)
3. Helps in regular spacing of collagen fibers to ensure
transparency
16
Keratocytes
Figure 8 Structure of keratocytes
These cells are Long, thin, flattened cells (maximally 2μm
thick) running parallel to corneal surface between the lamellae.
Having long flattened nuclei, sparse cytoplasm but contains full
component of organelles. [Fig 8]
Function
These cells are responsible for synthesis and maintaining of
collagen & proteoglycan substance of stroma.
It helps in corneal regeneration after injury
Part of corneal anti-oxidant defense (proteinase inhibiter,
inhibitors of metalloproteinases e.t.c) Other cells include
Lymphocytes, macrophages and polymorphonuclear
leucocytes also found in stroma ocationally.
17
DUA'S LAYER
Figure 9 -Layers of cornea showing Dua’s layer
It is hypothetically 15 micrometres (0.59mm) thick, the
fourth caudal layer, and is located between the corneal stroma and
Descemet's membrane. The layer is very strong and impervious to
air. On scanning electron microscopy, the anterior surface of Dua’s
Layer shows parallel bundles of collagen regularly arranged while
the posterior surface shows a smooth pleated pattern made of
coarse bundles of collagen and differs from the appearances of the
deep stroma and Descemet’s membrane. [Fig 9]
18
DESCEMET’S MEMBRANE: (POSTERIOR LIMITING
LAYER)
Figure 10 Descemet’s membrane - zones
It is the basal lamina of corneal endothelium. First appears at
2nd month of gestation and synthesis continues throughout adult
life
Thickness –
birth : 3 – 4 μm
childhood : about 5μm
adult : 10 – 12 μm
It has two zones [Fig 10]-
Anterior 1/3 zone that is developed in utero which is
irregular
19
Posterior 2/3 zone that is developed after birth
Major protein of DM is Type IV collagen
Schwalbe’s line:
The peripheral rim of DM is the internal landmark of corneal
limbus and also it is the anterior limit of drainage angle.
ENDOTHELIUM:
Fig 10 : Normal endothelium ( specular microscopy)
It comprises of a single layer of hexagonal, cuboidal cells
attached posterior aspect of DM [Fig 10]. It is mesenchymal in
origin.
20
Endothelial cells density :
At birth endothelial density is about 6000 cells/mm².
26% of cells are lost in 1st year. Further 26% lost over next
11 years. Rate of cell loss slows and stabilizes around middle
age and then it is about 2500 cells/mm². If cells density falls
below 500 cells/mm² corneal oedema develops and
transparency will be compromised.
Ultrastructural features
Single oval nucleus located centrally
Endothelium is rich in subcellular organelles with
large number of mitochondria, both rough and smooth
endoplasmic reticulum, free ribosomes, reflecting its
high metabolic acticity.
The posterior cell membrane (apical) facing anterior
chamber shows 20-30 microvilli which increases
absorption area
Cellular junction
o The anterior cell membrane (Basal) is attached with
DM by modified hemi-desmosomes
o Anterior 2/3rd – maculae adherens
21
o Posterior 1/3rd & apico-lateral edges – maculae
occludens
Endothelial functions
a) Maintains corneal hydration(slightly dehydrated state-
78% hydration) by ‘pump-leak hypothesis’-
1. Providing physiological barrier to salts and
metabolites to stroma.
2. Active transport transport of bicarbonate by
Na+/K+ATPase actively removes H2O from stroma by
pump action.
3. NA+/K+ATPase is located at the endothelial cell
membrane
Using ATP, the pump actively transport Na+, K+ and
bicarbonate to the AC
Creates + osmotic gradient in the aqueous
H2O moves from stroma to AC
LIMBAL STEM CELLS:
Only 5% to 15% of the cells in the limbus are stem cells.
The basal cells of limbal epithelium comprises the limbal stem
cells. They are the precursor for all other cells of the tissue. They
22
have a self maintaining population. They account for only a small
portion of total cells of the tissue. In vivo, they show slow cycling,
but in vitro, they demonstrate high potential to proliferate. They
cannot be differentiated from the rest of the cells of tissue.
CORNEAL NUTRITION & METABOLISM
Cornea requires energy for normal metabolic activities as
well as for maintaining transparency and dehydration.
Energy is generated by the breakdown of glucose in the form
of ATP.
Most actively metabolizing layers are epithelium &
endothelium
Sources of Nutrients:
Oxygen – mainly from atmosphere through tear film, with
minor amounts supplied by the aqueous and limbal vasculature
Normal Po2 in tears is 155 mm Hg. In aqueous is about 40
mm Hg. Minimum 25 mm Hg Po2 is needed for maintaining
deturgescent state and transparency Glucose, amino acid,
vitamins, and other nutrients supplied to cornea by aqueous
humor, a lesser amounts from tears or limbal vessels.
23
Glucose is also derived from glycogen stores in corneal
epithelium.
Epithelium consumes oxygen 10 times faster than stroma.
METABOLIC PATHWAYS:
Three processes or pathways –
1. Pentose shunt (Hexose monophosphate shunt) – occurs
both In hypoxic and normoxic conditions. Forms NADPH
and Pentose (Ribose 5-P) from glucose which are used in
nucleic acid synthesis.
2. Glycolysis (Embden meyerhof pathway) –
Glucose/glycogen converted to pyruvate yelding 2 ATPs
3. TCA or Krebs or citric acid cycle – in aerobic
conditions pyruvate is oxidized to yield 36 ATP, water, CO₂.
BLOOD SUPPLY OF CORNEA:
The cornea is an avascular structure with small loops derived
from the anterior ciliary vessels invading the periphery for
about 1 mm.
These loops are in the subconjunctival tissue which overlaps
the cornea
24
NERVE SUPPLY OF CORNEA
Figure 11 Nerve supply of cornea
Cornea is rich in sensory nerve supply derived from the
ophthalmic division of trigeminal which gives branches to
Nasociliary nerve and Ciliary nerves (terminal branch)
Ciliary nerve enter the pericoroidal space a short distance
behind the limbus.
60-80 myelinated branches pass into cornea
25
1-2 mm from the limbus nerves axon lose myelin sheaths
and divide into
anterior branches
posterior branches
Anterior nerves (40-50) pass through stroma and form
plexus subjacent to Bowman’s layer Nerve fibres then penetrate
Bowman’s layer and form subepithelial plexus Fibres then
divide dichotomously to form a parallel network which run for
upto 2 mm and give rise to fine free nerve terminals to
superficial epithelial layers
The posterior groups of nerves (40-50) pass posteriorly to
innervate the posterior stroma excluding Descemet’s membrane.
CORNEAL TRANSPARENCY
The cornea transmits nearly 100% of the light that enters it.
There are various factors that affect corneal transparency. Corneal
transparency is achieved by:
Physical/Anatomical factor
Optically smooth tear film
Uniform and regular arrangement of non-keratinized
epithelium
26
Peculiar arrangement of stromal lamellae
Uniform refractive indices of all layers
Avascularity
Absence of myelin sheath around corneal nerves
Physiological factor
Relative state of dehydration
OPTICALLY SMOOTH TEAR FILM
Forms an optically smooth and homogenous layer over
anterior surface of cornea. Fills up small irregularities of corneal
surface. Conditions associated with pre-corneal tear film results in
loss of corneal transparency.
UNIFORM AND REGULAR ARRANGEMENT OF NON-
KERATINIZED EPITHELIUM
Normal epithelium is transparent owing to the homogenicity
of refractive index.
27
ARRANGEMENT OF STROMAL LAMELLAE
Two theories –
Figure 12- Maurice's theory of corneal transparency
Maurice (1957):
The transparency of the stroma is due to the lattice
arrangement of collagen fibrils. Cornea is transparent because the
collagen fibrils are arranged in a regular lattice so that the scattered
light is nullified by mutual interference. Fibrils are arranged
regularly in a lattice form, separated by less than a wavelength of
visible light wave (4000 to 7000A). He explained, because of
their small diameter and regularity of separation, back scattered
light would be almost completely suppressed by destructive
interference25.
28
Goldman et al. (1968):
He suggested a perfect crystalline lattice periodicity is not
always necessary for sufficient destructive interference. His theory
nullifies the need of lattice arrangement to maintain transparency
by diffraction theory. It postulated that fibrils are small in
relationship to the light and will not interfere with light tranmission
unless they are larger than half of a wavelength of visible light i.e.
2000
AVASCULARITY OF CORNEA
Cornea is avascular except for small loops which invade the
periphery for about 1 mm. Pathological incidents leads to corneal
vascularisation. Progressive corneal vascularisation is harmful as it
interferes with the functional properties of cornea.
ABSENCE OF MYELIN SHEATH AROUND CORNEAL
NERVES
Corneal nerves loose their myelin sheaths at 1-2 mm away
from the limbus.Thin and sheath-less nerves produces very little
scattering of light.
29
RELATIVE STATE OF CORNEAL DEHYDRATION
Cornea has the highest water content than any other
connective tissue in the body i.e. 78%. Four Factors are responsible
for keeping the water content constant:
FACTORS AFFECTING CORNEAL HYDRATION:
STROMAL SWELLING PRESSURE EXERTED BY
GAGs
Figure 13
Pressure exerted by corneal stroma mainly GAGs is stromal
pressure (SP).
Sp is 60 mmhg, is a keystone of corneal biophysics.
30
Anionic charges on GAGs molecule expands the tissue,
draws fluid with equal but negative pressure called
imbibation pressure.
IOP – SP or IP = 17 -60 = -43 mmHg
SP generates interfibrillar tension may be biophysical
mechanism to maintain fibrils normal arrangement.
BARRIER FUNCTION OF EPITHELIUM AND
ENDOTHELIUM
EPITHELIUM
Zonulae Occludentes
Desmosomes
Hemidesmosomes
ENDOTHELIUM
Not effective as epithelial barrier
Forms leaky channels allowing fluid to enter into stroma.
Calcium dependent
HYDRATION CONTROLED BY ACTIVE PUMP
MECHANISMS OF THE CORNEAL ENDOTHELIUM
Na/K ATPase pump system
Most active
31
Active extrusion of Na
Ouabain – specific ATPase inhibitor
Bicarbonate dependent ATPase
Present in mitochondria, not on Plasma membrane.
Thiocyanate – specific inhibitor.
Essential for the maintenance of the corneal thickness
Carbonic Anhydrase Enzyme system
Produces bicarbonate and hydrogen ions.
CA inhibitors – results in corneal edema further proving
its role.
Na/H pump
EVAPORATION OF WATER FROM THE CORNEAL
SURFACE.
Evaporation leads to increased osmolarity of precorneal tear
film.
Hyperosmolarity of pre-corneal tear film draws in water
from cornea.
Helps maintaining dehydration of cornea.
32
CORNEAL EDEMA
In normal cornea, optical transparency is directly related to
the state of hydration of the tissue. If cornea swells, it increases the
thickness and surface becomes irregular. Both these changes
downgrades its optic properties
Etiology of corneal edema:
PRIMARY CAUSES
SECONDARY CAUSES
PRIMARY CAUSES
PRIMARY ENDOTHELIAL DYSTROPHIES:
Dystrophies involving endothelium & Descemet’s
membrane causes symmetrical marked stromal edema which is
gradually progressive over a period of years.
-Congenital hereditary endothelial dystrophy:
They are characterised by diffuse edema at birth or soon
thereafter, without significant anterior segment abnormalities.
-Posterior polymorphous dystrophy:
They are characterised B/L vesicular or linear lesions at the
level of descemet’s membrane & endothelium is present, it presents
with congenital corneal edema.
33
-Fuch’s Endothelial dystrophy
AD pattern of inheritance. Earliest changes are limited to
posterior cornea & presents with central B/L asymmetrical corneal
guttata. In fuch’s dystrophy endothelial cells transform into
fibroblast like cells that are capable of secreting collagen fibrils.
These changes lead to BM thickening. Progressive endothelial
decompensation leads to stromal & epithelial edema.
Bullous keratopathy
It represents the terminal stage of severe epithelial edema. In
the affected area the epithelium is irregular. Bullae are formed over
the surface. They appears in the form of blebs. After 2-3 days the
bullae rupture, and again reappear. This cycle associated with
considerable irritation & pain.
SECONDARY CAUSES
MECHANICAL TRAUMA
1. Blunt non penetrating injury causes edema by injury to
endothelium.
2. Perforating injuries cause direct damage to the cornea.
3. Forceps delivery puts pressure on the globe and may cause
edema due to DM tear.
34
4. Noxious chemicals mainly alkalies which penetrates cornea
can cause endothelial damage.
5. Intraocular surgeries can cause acute endothelial loss most
notably in superior & central cornea.
6. Lasers used for iridotomy can cause focal corneal edema.
7. High altitude corneal decompensation has been reported
causing hypoxia induced corneal edema.
GLAUCOMA
Acute rise in IOP which exceeds swelling pressure of stroma
causes epithelial edema.
Hypoxic endothelial decompensation occurs due to
diminished aqueous flow.
Chronic elevation of IOP permanently damages the
endothelium.
In hypotony, AC is shallow or flat. Mechanical trauma by
cornea iris or iris corneal touch leads to edema.
CONTACT LENSES
Most common cause of corneal edema is prolonged use of
contact lens.
35
It is mainly due to insufficient supply of oxygen to
epithelium.
Edema presents as microcystic epithelial edema near the
center of resting position of the lens.
Edema easily clears if contact lens is removed.
ICE SYNDROME
Iridocorneal endothelial syndrome is basically spectrum of
disorders that includes
A) Progressive iris atrophy.
B) Chandler’s syndrome.
C) Iris nevus syndrome (Cogan Reese)
36
Chandler’s syndrome
Figure 14- Chandler's syndrome
Corneal endothelial abnormalities (hammered silver
appearance) will be Present. Characterised by corneal edema,
Corectopia, Glaucoma may be less severe. chandler syndrome have
more severe corneal edema
37
Cogan Resse syndrome
Figure 15- Cogan-Reese syndrome
Characterised by diffuse naevus which covers iris or iris
nodules. Iris atrophy may be absent in 50% of patients, but
corectopia & glaucoma may be severe.
38
Essential iris atrophy
Figure 16- Essential Iris Atrophy
Characterised by distortion of pupil, peripheral anterior
synechie & iris atrophy, with full thickness holes. Glaucoma
commonly present in the involved eye. Unilateral in occurrence.
39
MANIFESTATIONS OF CORNEAL EDEMA
Clinical manifestations depends upon the cause & degree of the
condition.
Mild discomfort in conditions like fuch’s dystrophy.
Severe neuralgic pain is seen in bullous keratopathy.
Coloured haloes.
Severe visual loss.
MANAGEMENT OF CORNEAL EDEMA
Treating the causative factor is the primary aim of treatment.
The treatment measures are broadly classified into :
Medical management
Surgical management
MEDICAL MANAGEMENT
AIM : To reduce epithelial or stromal edema.
To reduce anterior chamber inflammation.
To improve the endothelial function of cornea.
SUPPRESSION OF INFLAMMATION
Topical steroid is used as a treatment of choice in cases
where inflammation has caused the endothelial dysfunction. Most
40
cases show dramatic response. Corneal edema secondary to
keratouveitis show dramatic response to steroids.
IOP REDUCTION
Raised IOP causes epithelial edema. In all cases of corneal
edema where IOP is high, topical anti-glaucoma medications or
carbonic anhydrase inhibitors can be used. If IOP remains high
inspite medical management, surgical measures can be resorted to.
HYPERTONIC AGENTS
5% sodium chloride is commonly used. It withdraws water
from the epithelium by osmosis. Treatment will be effective if the
epithelium is intact and is capable of functioning as a semi
permeable membrane.
Disadvantages of hypertonic agents:
Causes discomfort and pain.
They do not reduce stromal edema because
hypertonicity of tear film can extract only small
amounts of stromal edema.
41
BANDAGE CONTACT LENS
They promote healing and relieve corneal pain in many
corneal conditions. It is of particular use in bullous keratopathy.
Mechanism of Action :
BCLs tamponade the corneal surface, reinforces the
damaged tissue thereby allowing the protected migration,
replication and attachment of corneal epithelial cells. They protect
the epithelium and exposed nerve from rubbing against the lids
during blinking. They also flatten the bullae.
42
SURGICAL MANAGEMENT
ANTERIOR STROMAL PUNCTURE
Anterior stromal puncture breaches the Bowman’s
membrane creating a localised area of subepithelial fibrous tissue.
This enhances the adherence of epithelium to the underlying tissue.
It provides symptomatic relief in painful bullous keratopathy. It is
done under topical anesthesia using a 26G needle with penetration
depth of less than one-fourth of stromal thickness. After
completing the procedure, a bandage contact lens can be applied.
The procedure can be repeated. A significant reduction in pain and
tearing was achieved.16
PENETRATING KERATOPLASTY
Figure 17- Penetrating keratoplasty
43
Keratoplasty is indicated in conditions not ameanable to
medical therapy. It can be in the form form of a full thickness
penetrating keratoplasty or an anterior or posterior lamellar
keratoplasty (DALK, PDEK, DMEK, DSEK etc) depending on the
pathology or surgeon’s skill and discretion. However, performing a
keratoplasty requires a good donor cornea which can be obtained
only with an attached eye bank and the outcome of the surgery
depends on the surgical skill and expertise of the surgeon.
KERATOPROSTHESIS
Figure 18- Keratoprosthesis
Indicated in cases of multiple graft failure, especially if
corneal thickness exceeds 1.5mm. Undertaken only when there a
reasonable prospect for vision. The prosthesis is held in place by
either an intralamellar flange of fenestrated Teflon or acrylic or
44
“nut and bolt” implant in which a coloured contact lens or corneal
graft is placed in the optical centre.
THERAPEUTIC (BANDAGE) CONTACT LENS
The five main aims of therapeutic contact lenses are :
1.Ocular pain relief
2. Promotion of corneal healing;
3. Mechanical protection and support;
4. Maintenance of corneal epithelial hydration;
5. Drug delivery.
Choice of therapeutic lens available are as follows :
o Hard (PMMA) and RGP lenses
o Hard scleral rings
o Hydrogel soft lens
Low water content( 38%-45%)
Mid-water content (45%-55%)
High water content (67%-80%)
o Silicone rubber and silicone hydrogels (38%)
o Collagen shields (Dk/L = 63% H20 soft lens)
And give rise to fine free nerve terminals to superficial
45
The choice of lens depends on :
1. The aim of use
2. The physiological requirement of the diseased eye. Disposable
contact lens provide a very cost effective option in many
cases.
ESSENTIALS OF FITTING A BCL
This guide refers mainly to soft bandage contact lenses : -
Keratometry is not of much help due to the irregular mires
associated with any underlying condition, .Therefore, trial
fitting is best recommended. However, K readings of the
other eye may be helpful.
Avoid the use of topical anaesthetics wherever possible as it
may mask the pain associated with an ill-fitting lens.
The lens fit should be assessed after 20 minutes and again
after 60 minutes (owing to lens dehydration effects);
Peripheral lens fit is equally important as flared lens edges
may gives rise to discomfort.
A well fitting TCL should have good corneal coverage.
46
A well centered large lens with a fitting more on the flat
side is the preferred option in cases such ascorneal oedema
and conditions where the cornea epithelium is not intact.
A steeper fitting lens is preferred for eyes with irregular
corneal topography.
INDICATIONS OF THERAPEUTIC CONTACT LENS
BASED ON AIM OF USE :
Aim 1: RELIEF OF PAIN
BULLOUS KERATOPATHY
47
1. In a patient with a painful eye with no visual potential.
Best fitted with a BCL as soon as possible.
Lens movement in should be minimised (but sufficient
to allow adequate tear flow). Use a large, hydrogel lens with
high water content to maintain the maximum oxygen
permeability for continuous wear.
2. In a patient who is not fit for graft surgery.
3. As a temporary measure for pain relief for a patient
planned for keratoplasty at a later date.
A thin high water content BCL is indicated due to the
reduce the risk of corneal vascularistion.
4. Filamentary Keratitis
Severe persistent cases may benefit from the use of
BCL in addition to steroids, atropine with filament removal
Consider the use of disposable contact lens.
Possible resolution of filaments within 4 days and
complete disappearance within 2 weeks . However,
recurrence is common.
5. Superior limbic keratoconjunctivitis
BCLs are very effective in improving both signs and
symptoms.
48
6. Thygeson’s superficial punctate keratitis
Thygeson’s SPKs has recurrent episodes of fine
superficial punctate corneal opacities of postualated viral
aetiology. It causes distortion of the epithelial surface and
reduce visual acuity.
In severe cases a high water content BCL is the best
choice to act as a pressure bandage thus relieving pain and
foreign body sensation. Often a low water content thin lens
works better.
Aim 2: PROMOTION OF CORNEAL HEALING
A. RECURRENT CORNEAL EROSION: - Anterior
membrane dystrophies
They frequently produce intermittent epithelial
breakdown and is associated with corneal surface and
wetting problems.
Most frequently caused by map-dot-finger dystrophy.
10% develop recurrent erosion syndrome.
Best option – extended wear contact lens.
Recurrent corneal erosions may benefit from Excimer
laser phototherapeutic keratectomy.
49
B. TRAUMATIC CORNEAL ABRASIONS
Abrasions over 4mm benefit mostly from the use of
BCL.
The use is disposable lenses is indicated with good success.
C. CHEMICAL INJURIES
Collagenolyitc enzymes causes stromal ulceration
secondary to chemical injury.
BCL acts as a barrier in preventing the passage of
these protelytic enzymes into the tear film thus preventing
progeressive ulcerative process.
Small diameter bandage contact lenses are the first
choice.
If lid involvement is present, scleral lenses are preferred.
D. PERSISTENT CORNEAL EPITHELIAL DEFECTS
(PEDs)
It is a chronic problem which makes cornea vulnerable
to infection and is associated with a high rate of ulceration
and perforation.
Disposable bandage contact lens provide mechanical
protection from lids as the epithelium regrows.
50
Experimentally, collagen shield hydrated in fibroblast
growth factor has also been tried with good results.
E. POST OPERATIVE EPITHELIAL DISORDERS
It is most commonly associated with
Vitrectomy
Penetrating keratoplasty in the early post operative
period.
Epikeratoplasty
Corneal refractive procedures.
Soft and collagen BCLs may be utilised to provide a stable
healing environment and promote rapid healing.
AIM 3: MECHANICAL PROTECTION AND SUPPORT
BCLs provide structural support and act as a splint in
cases of corneal thinning, perforation and partial wound
dehiscence.
The use of BCL in such cases can delay or even alleviate
the need for immediate surgery or grafting.
51
A. CORNEAL LACERATION
Use of BCLs provide structural support, promote good
healing and integrity for small corneal perforations ( less
than 2mm).
BCLs can be used over small perforations sealed with
cyanoacrylate glue and this helps provide protection to
this adhesive plug over the corneal wound and from the
shearing effects of lid action.
B. CORNEAL WOUND LEAKAGE POST
OPHTHALMIC SURGERY
Ophthalmic surgeries particulary ECCE and
penetrating keratoplasty can be associated with aqueous
leakage.
BCLs provide mechanical splinting of the wound and
so aids sealing of the leaking wound.
However, complete anterior to posterior wound
dehiscence is a contraindication to the use of BCLs.
52
C. TRABECULECTOMY
BCLs are indicated in leaking drainage bleb in the
post operative period. Large diameter BCLs can reduce
bleb leak by mechanical intendation.
D. CORNEAL THINNING
BCLs prevents imminent perforation in cases with
corneal thinning. BCLs act as a corneal splint and reduce
or stop the rate of thinning and thereby prevent
subsequent perforation.
E. PROTECTION OF THE CORNEA
BCLs provide protection and comfort of cornea in cases
of
Neurotrophic keratitis
Trichiasis
Entropion
Lid deformities with corneal exposure
F. CICATRIZING CONJUNCTIVAL DISEASE
Steven Johnson syndrome, ocular cicatrical
pemphigoid, chemical burns, chemical burns and dry eye
53
are associated with corneal involvement with
conjunctival cicatrisation. In Stevens Johnson syndrome
scleral lenses may be useful, as they retain a reasonable
tear layer which prevents corneal dehiscence and
keratinisation
AIM 5: DRUG DELIVERY
Medication impregnated lenses are appropriate for
short-term use when corneal protection and therapeutic
levels of specific medications are desired.
COMPLICATIONS ASSOCIATED WITH BANDAGE
CONTACT LENS
Most complications of BCLs are that associated with
extended wear contact lens. Some of the specific
complications include :
Microbial keratitis
Giant papillary conjunctivitis (GPC)
Neovascularisation
Corneal hypoxia
54
HYPEROSMOTIC CONTACT LENS
Hyperosmotic Contact Lenses Device Description:
The Hyperosmotic Contact Lenses are fabricated
from Acofilcon A, which in the dry (unhydrated) state may
be machined and polished. The hydrophilic nature of this
material allows the lens to become soft and pliable when
immersed in an aqueous solution.
The co-polymer consists of 41% Acofilcon A and
59% water by weight when immersed in normal buffered
saline solution.
In the hydrated state, the lens conforms to the
curvature of the eye covering the cornea and extending
slightly beyond the limbus forming a colorless, transparent
optical surface. The soft hydrophilic contact lens has a
spherical back surface. The hydrophilic properties of the lens
require that it be maintained in a fully hydrated state in a
solution compatible with the eye. If the lens dries out, it will
become hard and appear somewhat warped, however, it will
return to its proper configuration when completely
rehydrated in the proper storage solution.
55
The Hyperosmotic Contact Lenses design includes the
following characteristics:
1) Two different base curves (creates a tear reservoir)
2) A peripheral groove including fenestrations (increase
tear exchange and accessibility)
When worn on the eye the Hyperosmotic Contact Lens
design creates a tear film reservoir between the corneal
surface and the back surface of the contact lens. The
fenestrations increase tear film exchange.
The hydrophilic characteristics allow aqueous solutions
to enter the lens and in its fully hydrated state the lens is
approximately 59% water by weight. The physical properties
of the Hyperosmotic Contact Lenses are:
Refractive Index 1.403 (hydrated)
Light Transmission (@600nm) greater than 94%
Water Content 59 %
Oxygen Permeability 26 X 10-11 (cm2/sec) (ml
O2/ml x mm Hg @ 35oC),
(revised Fatt method).
56
The Hyperosmotic Contact Lenses are available in the
following parameter ranges:
Diameter: 10.0 mm to 17.0 mm
Base Curve: 6.0 mm to 9.0 mm
Center Thickness: 0.12 mm at -3D
Figure 19- Scheme of Hyperosmotic contact lens
Figure 20 Hyperosmotic lens design
57
Device Principle of Operation
The unique structure of the lens (Figure 19,20) is by lathe of
a reservoir around the back- central part of the lens, which
functions as a hyperosmotic media, by a pumping mechanism, thus
enabling flowing of water from the corneal stroma to the contact
lens, and from there outside by evaporation.
The Hyperosmotic contact lens treats corneal edema by
either extracting corneal fluids by osmosis into the contact lens or
by increasing evaporation of water from the posterior part of the
lens by breaking up the lipids layer so fluids are absorbed from the
cornea to the solution. When water evaporates from the solution,
the ion concentration inside the phase trapped between the lens and
the cornea (reservoir) increases. Due to the hypertonic pressure
created in the microenvironment layer (reservoir), fluid is absorbed
from the edematous cornea to the solution. The ionic pump is
described in (Figure 21).
58
Figure 21- Schematic mechanism of water evaporation from
the Hyperosmotic Lens
Intended Use
The Hyperosmotic lenses are indicated for therapeutic use to
protect the corneal surface and helps relieve corneal pain in the
treatment of acute or chronic ocular pathologies, such as corneal
erosions, bullous keratopathy, entropion, corneal edema, and
corneal dystrophies and post-surgical conditions resulting from
cataract extraction and corneal surgery. The lenses may be used
for daily wear with removal for cleaning and disinfection. It
also provides optical correction during healing if required.
59
AIM AND OBJECTIVE
To evaluate the safety and efficacy of the Hyperosmotic
contact lens in subjects suffering from corneal edema and to
compare the efficacy of the Hyperosmotic contact lens to standard
treatment with regular bandage contact lens.
60
MATERIALS & METHODS
This prospective comparative study was conducted at Cornea
department, RIOGOH, Egmore, Chennai for a period of 6 months
Methodology:
Patient presenting to Cornea and contact lens services was
registered, evaluated and followed up during the study period.
For Subjects who met the inclusion criteria, detailed medical
and ophthalmic history, best corrected visual acuity, CCT by
pachymetry, intraocular pressure was done at the time of
presentation.
Each subject was treated for 7 days with the Hyperosmotic
contact lens with salt solution.
One week (7 days) of washout without any treatment.
Followed by 7 days with regular bandage contact lens with
salt solution.
Clinical evaluation was performed at 7, 14, 21 days post
baseline.
Best corrected visual acuity, CCT by pachymetry,
intraocular pressure, concomitant medications, adverse events and
comfort were documented during each visit.
61
Subjects were asked to stop using any ophthalmic treatment
related to the corneal edema 2 to 7 days before applying the
Hyperosmotic contact lens besides steroid drops or anti glaucoma
drops.
In case the subject is already without any corneal edema
treatment for 2 to 7 days, subject was started on treatment with
Hyperosmotic contact lens according to his regimen treatment.
INCLUSION CRITERIA:
1. Subject age > 18 years old
2. Subject with chronic corneal edema of more than 3 months
duration.
3. Subject with of 6/24 or worse (equivalent ETDRS) clinically
explained by corneal edema.
EXCLUSION CRITERIA:
1. Subject with active Herpes keratitis.
2. Subject with scarring of cornea.
3. Subject who is suffering from corneal infections and erosions
(red eye)
62
4. Subject who require chronic administration of any topical
ophthalmic beside lubricant eye drops and steroids or anti
glaucoma drags
SCREENING PROCEDURES/ VISITS:
The visit includes subject's qualification assessment for
inclusion/exclusion criteria as described above. Informed consent
was signed.
Complete anamnesis will be taken including subject's
medical complaints, medical history, and medication use.
Day 0:
Subject was asked to stop using any treatment for 7 days
(beside steroid drops or anti glaucoma drops) and have the
following procedures/visits:
In case the subject is already without any corneal edema
treatment for 7 days, subject was begun immediately with the use
of Hyperosmotic contact lens with salt solution.
Day 7:
Subject had clinical follow-up and treatment was stopped.
63
Day 7-14:
Washout period of first treatment. Subject can continue
steroids or anti glaucoma medication.
Day 14:
Subject had clinical follow-up and was started on the second
treatment with regular bandage contact lens with salt solution.
Day 21:
Subject had clinical follow-up.
All visits included ophthalmic examinations- best corrected
visual acuity, slit lamp examination, CCT by pachymetry,
intraocular pressure by Icare, concomitant medications used and
recording of adverse events and comfort.
64
ASSESSMENTS OF PARAMETERS :
BCVA
CCT by pachymetry
Intraocular pressure by Icare.
65
52%48%
Gender Distribution
F
M
OBSERVATION AND ANALYSIS
The average age of a patient is 55.70 years with the standard
deviation of 13.75 years. The distribution of gender shows that
52% are female and 48% are male, while 35% of the cases were
left eyes (OS) and 65% of the cases were right eyes (OD). Also,
88% of the patients were found to be diagnosed with PBK, while
only 12% of the patients were found to be diagnosed with ABK.
(Refer the following Pie Charts).
66
12%
88%
% of Diagnosis
ABK
PBK
65%
35%
% of Eyes
OD
OS
67
92%
8%
VISUAL ACUITY POST TREATMENT WITH HCL
SAME V/A
IMPROVEMENT IN V/A
68
12.29
4.39
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
HYPER-OSMOTIC BANDAGE
Mea
n %
Red
uctio
n in
CCT
Mean % Reduction in CCT - Hyper Osmotic Vs Bandage
To test whether there is significant difference in % reduction in
CCT between “Hyper-Osmotic Contact Lens” and “Bandage
Contact Lens”
Hypotheses:
Null hypothesis, H0: There is no significant difference in %
reduction in CCT between “Hyper-Osmotic Contact Lens” and
“Bandage Contact Lens”
Null hypothesis, Ha: There is significant difference in %
reduction in CCT between “Hyper-Osmotic Contact Lens” and
“Bandage Contact Lens”
Test applied:
Independent Samples t-test
69
Result:
t = 23.01 & p-value = 0.000 < 0.05
Conclusion:
Since the p-value of the test statistic is less than 0.05, we
reject the null hypothesis at 5% level of significance. Hence, the
evidence is sufficient to conclude that there is significant difference
in % reduction in CCT between “Hyper-Osmotic Contact Lens
with Salt Solution” and “Bandage Contact Lens with Salt
Solution”. Going by the mean values, we see that the mean %
reduction in CCT by Hyper-Osmotic Contact Lens (12.29) is
greater than that of Bandage Contact Lens (4.39), which indicates
that “Hyper-Osmotic Contact Lens with Salt Solution” is better
than “Bandage Contact Lens with Salt Solution” in terms of
mean % reduction in CCT.
70
15.08
15.30
14.95
15.00
15.05
15.10
15.15
15.20
15.25
15.30
15.35
IOP_Pre IOP_Post
MEA
N IO
P
Mean IOP - Hyper-Osmotic
To test whether there is significant change in IOP from Pre to
Post Operation by Hyper-Osmotic Contact Lens
Hypotheses:
Null hypothesis, H0: There is no significant change in IOP
from Pre to Post Operation by Hyper-Osmotic Contact Lens
Null hypothesis, Ha: There is significant change in IOP
from Pre to Post Operation by Hyper-Osmotic Contact Lens
Test applied:
Paired Samples t-test
71
Result:
t = 0.43& p-value = 0.334 > 0.05
Conclusion:
Since the p-value of the test statistic is greater than 0.05,
we fail to reject the null hypothesis at 5% level of significance.
Hence, the evidence is not sufficient to conclude that there is
significant change in IOP from Pre to Post Operation by Hyper-
Osmotic Contact Lens with Salt Solution. In addition, the mean
IOP values appear to be approximately equal (i.e., approx. 15) for
both Pre and Post operation.
72
14.80
15.18
14.60
14.70
14.80
14.90
15.00
15.10
15.20
15.30
IOP_Pre IOP_Post
MEA
N IO
P
Mean IOP - Bandage
To test whether there is significant change in IOP from Pre to
Post Operation by Bandage Contact Lens
Hypotheses:
Null hypothesis, H0: There is no significant change in IOP
from Pre to Post Operation by Bandage Contact Lens
Null hypothesis, Ha: There is significant change in IOP
from Pre to Post Operation by BandageContact Lens
Test applied:
Paired Samples t-test
73
Result:
t = 1.18& p-value = 0.122> 0.05
Conclusion:
Since the p-value of the test statistic is greater than 0.05,
we fail to reject the null hypothesis at 5% level of significance.
Hence, the evidence is not sufficient to conclude that there is
significant change in IOP from Pre to Post Operation by Bandage
Contact Lens with Salt Solution. In addition, the mean IOP values
appear to be approximately equal (i.e., approx. 15) for both Pre and
Post operation.
74
DISCUSSION
Study results published by Dr. Claes Feinbaum and team
suggests that treatment of psuedophakic bullous keratopathy with
hyperosmotic contact lens could be an alternative to more drastic
options. The team reported a case of psuedophakic bullous
keratopathy treated with hyperosmotic contact lens. The study
showed that there was a substantial decrease in corneal edema from
850µm to 740µm. BCVA improved from 0.01to 0.03. The study
also reported substantial pain relief in the patient. However on long
term use, the lens was found to serve only as therapeutic contact
lens suggesting that these lenses are best used for short term
purpose.11, 12
Study published by Knezović I et all showed that that the
efficacy of hypertonic solution correlated with the severity of
bullous keratopathy. When 5% NaCl hypertonic solution was
applied in the early stage of the disease, when only stromal
component of corneal oedema was present, visual acuity and
pachymetry readings were significantly improved.
75
Study published by Rouland et al analysing the efficacy of
hypertonic solution in symptomatic corneal edema found that there
was reduction in corneal thickness, better visual acuity and
tolerability with minimal side effects.
76
RESULTS
1. Study comprised of 40 patients with 19 male patients and 21
female patients which represents a study population of 48%
male patients and 52% female patients.
2. The average age of a patient is 55.70 years with the standard
deviation of 13.75 years.
3. Of the cases studied, 35% ( 14 out of 40 eyes )of the cases
were left eyes (OS) and 65% (26 out of 40 eyes) of the cases
were right eyes (OD).
4. 88% (35 out of 40 ) of the patients were found to be
diagnosed with Pseudophakic bullous keratopathy, while only
12% (5 out of 40 ) of the patients were found to be diagnosed
with Aphakic bullous keratopathy.
5. The mean central corneal thickness for 40 patients with
corneal edema prior to treatment with hyperosmotic contact
lens with salt solution was 764.975µm.
6. The mean central corneal thickness for 40 patients with
corneal edema after treatment with hyperosmotic contact lens
with salt solution was 670.95µm.
77
7. The mean reduction in corneal thickness for 40 patients with
corneal edema post treatment with hyperosmotic contact lens
with salt solution was 94.025µm.
8. The mean percentage reduction of central corneal thickness
for 40 patients with corneal edema after treatment with
hyperosmotic contact lens with salt solution was 12.29%
reduction.
9. The mean central corneal thickness for 40 patients with
corneal edema prior to treatment with regular bandage contact
lens with salt solution was 767.775µm.
10. The mean central corneal thickness for 40 patients with
corneal edema after treatment with regular bandage contact
lens with salt solution was 734.125µm.
11. The mean reduction in corneal thickness for 40 patients with
corneal edema post treatment with regular bandage contact
lens with salt solution was 33µm.
12. The mean percentage reduction of central corneal thickness
for 40 patients with corneal edema after treatment with
regular bandage contact lens with salt solution was 4.39% .
13. The mean pre-treatment IOP for 40 patients with corneal
edema before hyperosmotic contact lens was 15.08 mm Hg.
78
14. The mean post – treatment IOP for 40 patients with corneal
edema after using hyperosmotic contact lens with salt solution
was 15.30mmHg.
15. The mean pre-treatment IOP for 40 patients with corneal
edema before bandage contact lens with salt solution was
14.80mm Hg.
16. The mean post – treatment IOP for 40 patients with corneal
edema after using regular bandage contact lens with salt
solution was 15.18mmHg.
17. Visual acuity improvement (by 1 metre) was noted in only 8%
(3 out of 40) patients post treatment with hyperosmotic
contact lens. However, no improvement in visual acuity was
noted in any of the patients post treatment with regular
bandage contact lens
18. Pain relief was reported by the subjects after using the
hyperosmotic contact lens.
19. No adverse event occurred during application of the
hyperosmotic contact lens. None of the lens designs caused
any side effects rather than normal irritation due to the
presence of a contact lens on the cornea.
79
CONCLUSION
This study was aimed to analyse the safety and efficacy of
hyperosmotic contact lens in the management of corneal edema. Results
show that there is a significant decrease in corneal thickness while
treating with hyperosmotic contact lens with salt solution in comparison
with a regular bandage contact lens with salt solution. This method of
treatment seems to be superior to the current standard of treatment using
hypertonic salt solution alone. No adverse events, or IOP change
occurred during the application of hyperosmotic contact lens. None of
the lens designs caused any side effects other than normal irritation due
to the presence of a contact lens on the cornea. Though the improvement
in visual acuity was noted in only 3 out of 40 patients using
hyperosmotic lens, pain relief was reported by all the subjects after
using hyperosmotic contact lens. This new treatment modality with
hyperosmotic contact certainly has a place in the treatment of corneal
edema. It can be of particular benefit in short term for symptomatic
relief in patients awaiting keratoplasty. Further studies with larger
groups are necessary for the long term outcome assessment of these
lenses.
PROFORMA
A STUDY ON THE EFFICACY OF HYPEROSMOTIC
CONTACT LENS IN THE TREATMENT OF CORNEAL EDEMA
NAME
AGE
SEX
IP NUMBER
DIAGNOSIS
BASELINE VISIT
Date of Visit: ____________________ (dd/mmm/yyyy)
I. Patient Enrolment
Inclusion Criteria (All items must be answered YES for patient to be
eligible)
Yes No
1. Subject age > 18 years
2. Subject with chronic (at least 3 months)
corneal edema.
3. Subject with visual acuity of 6/24 or worse
(equivalent ETDRS) clinically explained by
corneal edema
Exclusion Criteria (All items must be answered NO for patient to be
eligible)
Yes No
1. Subject with active Herpes keratitis
2. Subject with corneal scarring
3. Subject who is suffering from
corneal infections and erosions
4. Subject who require chronic administration
of any topical ophthalmic drugs beside
lubrication eye drops ,steroids or anti
glaucoma drugs
II. Enrollment Information
Date informed consent signed:________________ (DD/MMM/YYYY)
III. Baseline
Demographics
Date of birth:______________________ (DD/MMM/YYYY)
Gender: Male Female
Ophthalmic History (Pathology)
Right Eye Left Eye
No Yes If yes describe No Yes If yes describe
Cataract extraction > 1
month
Glaucoma
Previous glaucoma
filtering surgery
Contact lens intolerance ______________ ______________
Previous uveitis ______________ ______________
Diabetic retinopathy ______________ ______________
Previous retinal ______________ ______________
detachment
Macular Degeneration ______________ ______________
Allergy ______________ ______________
Corneal Transplant ______________ ______________
Eye surgery / Trauma ______________ ______________
Vitreal or Retinal Disease ______________ ______________
Refractive Laser ______________ ______________
Procedure >1mon
(specify method)
Cornea inlays ______________ ______________
Intraocular Laser ______________ ______________
treatment
Other_________ ______________ ______________
BIBLIOGRAPHY
1. Smolin G, Thoft RA, Dohlman CH. Endothelial function. The
Cornea: Scientific Foundations and Clinical Practice. 3rd ed.
Lippincott William & Wilkins: 1994. 635-643.
2. Cornea- Fundamentals, Diagnosis and Management-Krachmer.
3. Yanoff & Duker Ophthalmology- 4th edition
4. American Academy of Ophthalmology – External disease and
cornea Section 8 2015-2016.
5. Duane’s Clinical Ophthalmology by William Tasman Edward.
Volume 4, 6, 3.
6. Parson’s disease of the eye. 22nd edition.
7. Jack J. Kanski Clinical ophthalmology- 8th edition
8. Wolff’s Anatomy of the eye and orbit- 8th edition- Anthony. J.
Bron.
9. Oxford textbook of ophthalmology
10. Cornea Handbook- William B. Trattler
11. Claes Feinbaum and Ante Barisic. “Temporary Relief of Pain and
Improved Vision in Patient with Bullous Keratopathy by
Increasing Micro-Environment with a Specially Designed Soft
Contact Lens Resulting in Decrease of Corneal Oedema and Pain
Relief ”. EC Ophthalmology 3.4 (2016): 339-342.
12. Ophthalmology Times Europe-New treatment reduces corneal
oedema after cataract surgery -A new treatment modality with the
Hyper CL soft contact lens.May 01, 2015.By Claes Feinbaum.
13. Corneal edema after cataract surgery: incidence and etiology. Yi
DH1, Dana MR. Semin Ophthalmol.2002 Sep-Dec;17(3-4):110-4.
14. Reddy MK. Complications of cataract surgery. Indian J
Ophthalmol 1995;43:201-9
15. Narayanan et al., Pseudophakic corneal edema: A review of
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MASTER CHART
KEY TO MASTER CHART
1. CCT - Central Corneal thickness in µm
2. V/A - Visual acuity
3. IOP - Intraocular pressure in mmHg
4. PBK - Pseudophakic bullous keratopathy
5. ABK - Aphakic bullous keratopathy
