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Primary Congenital Glaucoma

Journal of Current Glaucoma Practice, May-August 2010;4(2):57-71 57

JOCGP

Primary Congenital GlaucomaUsha Yadava

Director, Professor of Ophthalmology, Maulana Azad Medical College and Allied Guru Nanak Eye Centre, New Delhi, India

Correspondence:Usha Yadava, Director, Professor, Glaucoma Services, Guru Nanak Eye Centre and Maulana Azad MedicalCollege, Bahadur Shah Zaffar Marg, New Delhi-110002, India, Phone: 91-1123234622 (O), e-mail: [email protected]

REVIEW ARTICLE

ABSTRACT

Glaucomas of the childhood are devastatinly deceptive in their presentations because of an insidious onset and late recognition. Primary

congenital glaucomas (PCG) which serve as a prototype for glaucomas in the young Subtleties of diagnosis may lie in simple symptoms

of watering and photophobia. This article is aimed to summarize all common manifestations and basics of surgical treatment, conventional

and contemporary. Parameters of diagnosis and success have been undergoing modifications from time to time, hence the need to take

stalk. How we look at childhood glaucomas in the light of conclusions drawn from glaucoma clinical trials in adults, evolving concepts of

risk factors like central corneal thickness at the first and subsequent visits are of practical concern.

Keywords: Childhood glaucoma, Pediatric glaucoma, Trabeculotomy, AGV.

INTRODUCTION

With the availability of medical literature on the click of a

mouse, it is important that specific querries be answered.

What are the Common causes and Age of Onset?

Childhood glaucomas are of three etiological types (Table 1)

and the commonest age of onset is under the first year of life,1,2

with 80% of patients present in the first year of life, out of which,

20% present as newborn glaucoma while the remaining 80%report as infantile glaucoma.3,4Conventionally, the term infantile

glaucoma is extended up to 3 years, after which it is termed

juvenile glaucoma. This ambiguity in the nomenclature is due

to the typical clinical features attributed to the distensible eye up

to three years. Some study groups are less rigid and prefer to

club all these together as Primary infantile and Congenital

glaucomas or Infantile glaucomas.5In any case, New born

glaucoma as a separate entity is important to recognize as this

is the most severe form with worst outcome.6

How Frequently do We see PCG?

There have been some additions to the older figures quoting anincidence of 1 in 5 years in general ophthalmic practice and

1/10,000 live births (LB).6 Results of a survey of newly

diagnosed cases by the British infantile and congenital

glaucoma study Group (BIG study) in three population groups

were published in 2007:5,7

1/18,500 LB in British caucasians

9 times higher in British-Pakistani population

1/30,200 LB in irish population.

Other Study Groups have Reported as Under

1/30,000 LB among Australians

Hungary: Higher incidence among gypsies

1/1,250 LB in Slovak nomads

,500 LB in Saudi Arabia

1 in 3300 LB in Andhra Pradesh

Brazil: 10.8% of 3,210 visually handicapped children

6.3% in China.

Higher incidence in inbred communities has got themolecular biologists striving to find some correlations between

genetic mutations and phenotypes in the hope of predicting the

onset or the severity of disease. Hyderabad group is leading in

this global research.8

What is the Gender Distribution and How oftendoes it affect both Eyes?

An interesting facta pseudoautosomal dominant pattern may

emerge in families with consanguinity at multiple levels with

seemingly equal predilection for either sex (Table 2).9

What is the Social Impact, if any of thisRare Disease?

It is true that this is a rare disease but we also know that glaucoma

causes progressive and complete blindness. With a long

anticipated life span, these children suffer economic blindness

and social discrimination and end up becoming a burden to the

society. There is also a higher chance of more than one just one

member of a family suffering. Hence, the importance of catching

Table 1:Shaffer-Weiss classification

Congenital 22.2% Developmental Glaucomas with associations 46%

Secondary 31.8%

Table 2: Gender ratio and bilaterality in PCG

Male:Female 2:3

Bilaterality 60 to 85%


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them young for treatment as well as parental counseling cannot

be over emphasized. Statistical estimations reveal that there

are 1.5 to 2 million glaucoma blind children globally, of which

2/3rd are in the developing nations. They constitute 15% of

blind school entries and 4.2% of all cases of pediatric

blindness.10

Which cases have the Worst Prognosis?

Patients presenting with severe corneal clouding in the first

year have the worst outcome (Figs 1A and B).6,11,12

What is the Role of Medical Therapy?

Glaucoma medications have a limited and palliative value in

PCG because of poor response and compliance. Child should

be started on medical treatment only as a stopgap and surgery

should be performed without further delay.12,13

Which Drugs are not to be used in Children?

Alpha 2 agonist group of drugs like brimonidine are

contraindicated in children < 2 years of age because of the risk

of apnea.12,13In general, prostaglandin analogues too are to be

avoided in unilateral glaucomas and prior to surgery.

Pilocarpine may paradoxically raise the intraocular pressure

(IOP) due to its action on the scleral spur, which may cause

further collapse of the trabecular meshwork due to the

abnormally high insertion of uveal tissue.14Short-term use of

a topical carbonic anhydrase inhibitor (CAI) and beta-blocker

(0.25% or 0.50%) either alone or in combination is a safer

choice in these cases. Betaxolol may be used in children with

asthma. Additional benefit with oral acetazolamide may be

obtained in very high levels of IOP as it seems to have an

additive effect with topical CAI drops in pediatric patients

unlike in adults.15Timolol instillation should be followed by

mechanical punctual occlusion for at least 3 to 4 minutes, to

minimize systemic absorption. In case, the surgical response is

incomplete postoperatively or late failure occurs, qualified

control with minimum medication may be achieved.16,17

What is the Best Surgical Option for these Patients?

An ideal surgical procedure aims to achieve the

following:11,17-19

Ensure short-term and long-term control of IOP

Should have no vision threatening complications.

Should the Small Infant undergo such MajorSurgery? Does an Ideal Procedure Exist?

Undoubtedly, on the basis of documented clinical evidence,

the one fact we do know is that delay is disastrous for vision.

Concerns about general anesthesia (GA) and surgical outcome

in babies have been put to rest in recent years with advances in

safe anesthesia for newborns with significant reduction in

morbidity and mortality associated with GA than yesteryears.

A calculated risk needs to be taken because complications like

hypothermia, apnea spells and hemorrhage have been reported

in newborns making a case for minimizing the use and abuse

of GA in newborns.20,21By far and large, modern anesthesia

and resuscitation methods have made surgical intervention quite

safe in newborns. No major complication were reported by

Mandal in 2003 in a study of 47 eyes of 25 patients of congenital

glaucoma operated under one month of age except one case of

hypothermia and one of uncontrolled bleeding from the trachea,

both resuscitated successfully. The above author prefers to

operate both eyes simultaneously as his way of maximizing

the care with the underlying need for urgency required to

manage such cases. Complete clearance of cornea was noted

in the same study in 66% of cases, IOP control at the end of 12

months of follow-up with the Kaplan-Meier survival rate of

89.4% and the mean glaucoma medication rate fell from 68.1%

to 14.9%.

Excellent visual outcomes and reversal of cuppingwith early intervention in these cases is known to occur

universally.16,22

There are several surgical options depending on the severity.

Let us first briefly summarize the relevant anatomy and

embryology of the anterior chamber (AC) angle for better

orientation and approach to the case at hand.

Anatomy and Embryology of the AC Angle

The limbal transition zone between the cornea and sclera

measuring 1 to 1.5 mm is bounded anteriorly by the end of the

Descemets membrane (Schwalbes line) and posteriorly bythe scleral spur, which is the outer landmark for the trabecular

meshwork (TM). The TM fills up an indentation or depression

Fig. 1A: Severe bilateral corneal clouding at birth

Fig. 1B: Bilateral ground glass edema of cornea due to bilateralbuphthalmos in a newborn


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known as the scleral sulcus on the under surface of the sclera in

front of the scleral spur and stretches anteriorly upto the

Schwalbes line (Fig. 2). Schlemms canal courses

circumferentially beneath the TM tissue. The ciliary muscle,on the other hand, takes attachment to the scleral spur, rendering

it taut so that the intertrabecular spaces do not collapse. The

same structures when viewed on gonioscopy are seen as lines

or bands peeping into the angle recess in the posteroanterior

order, i.e. iris, ciliary body, scleral spur, TM and Schwalbes

line.

Embryology of the AC Angle13,23

In general, ocular development goes through three stages:

Stage of embryogenesis (up to 3rd week): In the initial stages

after fertilization, sequential formation of three cellmassesmorula, blastula and lastly gastrula occurs. Cells

within the gastrula differentiate into three primary germ

layers: ectoderm, mesoderm and endoderm.

Stage of organogenesis (3rd to 7th week): Is the period of

organization of the segregated cells into rudimentary organs.

The lens separates from the surface ectoderm (6 weeks)

and the fetal fissure closes. The hitherto undifferentiated

mass of cells from the neural crest migrate to appear in the

vicinity of the anterior equator of the lens (Fig. 3) and give

origin to the corneal endothelium, stroma, iris, ciliary body,

trabecular meshwork and sclera. The limbus makes its

appearance and the AC appears as a potential space. The

three waves of neural migration now proceed as follows:

First wave forms the corneal and trabecular endothelium

Second wave forms corneal stroma

Third wave forms the iris stroma.

The anterior chamber boundaries are formed by the

cornea and tunica vasculosa lentis during the 7th week of

gestation.

Stage of differentiation (8th week onwards): With the

appearance of limbus, the rudimentary TM also appears.

The TM undergoes a process of internal reorganization so

that the highly specialized task of aqueous secretion andexcretion can begin. Following theories of meshwork

development have been proposed:

Atrophy and Absorption

Rarefaction

Cleavage Theory of growth and differentiation: This new and the

most accepted process was demonstrated by

McMenamin in his study of 432human fetal eyes.25

Trabecular tissue undergoes aprocess of differentiation

in which there appear gaps in the matrix with

reorganization of the cells so that the TM attains its

porous character with the creation of intertrabecular

spaces. The nonpigmented secretory epithelium of the

ciliary body gets thrown into folds by 12 weeks and the

longitudinal ciliary muscle development takes place in

the 4th month. Finally the primitive TM establishes

communication with the anterior chamber by 20 to 22

weeks of gestation. This is about the time the ciliary

body starts to function but the complete maturation of

the angle with regression of the hyaloid system occurs

by the 8thmonth. Further posterior movement of the

AC angle is a continuous process with full angle recess

formation achieved up to 6 to 12 months in the postnatal

period. Histopathology support was provided by

Anderson DR (1981) with demonstration of the high

insertion of the anterior uvea across the posterior TM

in the third trimester, persistence of which could be the

cause for compression of the trabecular beams leadingto congenital glaucoma. However, the possibility of

primary defects at various levels within the TM and

Fig. 2: Normal anterior chamber angle structures

Fig. 3: Origin of neural crest cells


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Suggested Sequence for EUA

Tonometry (as early as possible after induction and before

intubation)

External examination

Anterior segment examination

Corneal diameter measurement Fundus examination

Gonioscopy

Refraction, pachymetry, axial length measurement.

Preanesthesia

Each clinical parameter is important in a unique way, either in

diagnosis, prognosis or management of these children. With a

view to maximizing the advantages of EUA in these small

children, it is imperative that the surgeon/assistant be familiar

with all possible variables associated with GA. The need to

make a team with the anesthesiologist cannot be over

emphasized in PCG patients.11Informed consent for surgicalintervention must be taken prior to GA, prognosis and risk, if

any should always be explained beforehand. Parents must be

educated about (a) the type of glaucoma and (b) high demands

of care even after the operation and (c) the likely need for GA

in future.20

Do Anesthetic Agents alter IOP Levels?26,27

Anesthetic agents and dosage are known to alter the IOP

(Table 3). For this reason, high IOP in isolation should never

be the basis for diagnosis. Despite the inconvenience associated

with a GA event in terms of cost and time. A casual and

inconsistent reporting in EUA is not uncommon. This can leadto an aimless venture towards controlling a pressure, which was

erroneously recorded high.

Are these IOP readings Comparable to Adult Values?

IOP is also known to increase with age, hyperopia and corneal

thickness. Adult values are normally reached only after the early

teens (Table 4).27In a study of 405 Indian children up to the

age of 12 years Sihota et al found a mean overall value of IOP

as 12.02 .74 mmHg and 8 2.55 mmHg < 1year of age.

Adult values were achieved at 12 years of age.28

Photophobia, Watering, Redness, Pain

Severe photophobia causes the infant to bury the head into a

pillow. This symptom complex should be differentiated from

other causes of watering at this age. Symptoms of ocular

Schlemms canal has not been ruled out. Absence of

the Schlemms canal, whenever found has been thought

to be a secondary change. No true membrane exists as

believedearlier.

Gonioscopic Anatomy of a Normal Infant Eye (Fig. 4)23,24

Iris inserts posterior to the scleral spur

Flat iris insertion due to poor development of the angle

recess till the age of 6 to 12 months

Ciliary body band is distinct in most cases

TM appears thicker and more translucent than in adults.

When should Glaucoma be Suspected in an Infant?

Whenever the classical triad of watering eye, photophobia and

cloudy cornea is seen, glaucoma should be suspected and an

initial examination followed by examination under anesthesia

(EUA) with prior consent for surgical intervention should be

done.

Initial Examination

General systemic and ophthalmic examination is done to screen

for possible systemic associations; adnexal sources of irritation

in infants like epiblepharon, entropion and foreign body. Visual

responses are judged and preliminary digital tonometry may be

done whenever possible.12After the initial history and office

examination, EUA /surgery are planned (Fig. 5).

Fig. 4:Gonioscopic view of the anterior chamber angle

Fig. 5:The complete examination under anesthesia tray

Table 3: Effect of anesthetic agents on intraocular pressure26

IOP increases IOP decreases

Halothane

Succinyl choline Oxygen

Ketamine Nitrous oxide

Endotracheal intubation Sevoflurane

MidazolamMethohexitol

No change in IOP with oral chloral hydrate sedation.Tonometry with

< 1% halothane under the mask anesthesia is considered optimum.


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irritation are also common in buphthalmic eyes due to steep

corneas and poor tear film stability, appearing sometimes like

dry eye.

What are the Corneal Findings?Under the effect of high IOP, the ocular globe distends resulting

in buphthalmos meaning Ox Eye. This expansion leads to

typical stretch marks in the cornea called Haabs Striae

(Figs 6A and B, Fig. 7) due to ruptures in the elastic Descemets

membrane typically in the circumferential direction. With

passage of time the overlying edematous cornea undergoes

opacification. 80% of PCG eyes in India have severe corneal

cloudingsecondary to increased IOP during intrauterine life or

later in infancy (Fig. 8). Posterior embryotoxon can also be

noted in some cases (Fig. 9).

Table 4: Normal intraocular pressure by age27

Age in years IOP in mmHg*

Birth 9-6

0-1 10.6

1-2 12.0

2-3 12.6

3-5 13.6

5-7 14.2

7-9 14.2

9-12 14.3

12-16 14.5

*These values were obtained using a hand held noncontact

tonometer Pulsair, Keeler.

Figs 6A and B: Haabs striae

Fig. 7:Severe stretching of the limbus

Fig. 8: Buphthalmos in two patients

Fig. 9: Posterior embryotoxon in the anterior chamber (garland sign)

Differential Diagnosis of Corneal Clouding(STUMPED)29

Sclerocornea

Traumatic rupture

Metabolic

Peters anomaly Posterior polymorphous dystrophy of cornea

Endothelial dystrophy

Dermoid.


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Corneal Diameter

What about corneal diameter? What is the correct way tomeasure cornea in a stretched limbus (Fig. 7)?

Corneal diameter is measured by using callipersto measure the

horizontal and vertical diameters (Fig. 10). Under good ambient

illumination, callipers are held at the point of the first appearanceof the white scleral fibers on one side to the same point on the

other.This allows a measurement accuracy of approximately

0.5 mm. Normally, horizontal diameter measures marginally

more than vertical. Considering 9 to 10.5 mm as normal at birth,

taking > 12 mm in either meridian as abnormal at 1 year, one

should look for other evidence of glaucoma.23,29A value of

13 mm or more is definitely abnormal for all age groups. The

following formula has been worked out by Sherwin Isenberg

for interpretation in preterm babies:30

0.0014 Weight (in grams) + 6.3 = Corneal diameter

Developmental glaucoma may have anomalies like Micro-spherophakia with or without aniridia (Fig. 11), persistent

hyperplastic primary vitreous and congenital ectropion uvea

syndrome (Table 5).

Fig. 10: Measuring the horizontal corneal diameter inbilateral buphthalmos

Fig. 11: Microspherophakia with aniridia

Differential Diagnosis of Buphthalmos23,29,31

Congenital myopia Megalocornea

Anterior megalophthalmos

Keratoglobus

Secondary glaucomas.

Gonioscopy

Why is Gonioscopy done and which Gonioscope isPreferable?

Gonioscopy is done with Koeppes type direct goniolens

available in a set of different sizes for use in supine position.31

Direct goniolens gives an erect and panoramic view of the angleof the AC at a lower magnification than the commonly used

indirect gonioprism of the Goldman type in adults. It is also

Table 5: Other development glaucomas with associated anomalies

1 Iridocorneal endothelial syndrome Presence of corneal endothelial abnormalities

Unilateral ity

Absence of family history

Onset in young adult hood

2 Posterior polymorphous dystrophy Corneal endothelial abnormality

3 Peters anomaly Central portion of cornea, iris and lens involved

4 Aniridia Rudimentary iris

Peripheral corneal opacity and pannus

Localized congenital opacities in the lens, subluxation of lens or its complete absence

Foveal hypoplasia

Glaucoma develops in late childhood or adolescence

Mutation in PITX2 gene

5 Iridogoniodysgenesis Congenital hypoplasia of the iris without the anterior chamber angle defects

6 Oculodentodigital dysplasia Dental anomalies

Mild stromal hypoplasia

Anterior chamber angle defects

Microphthalmia

Glaucoma

Mutation in connexin-43 gene

7 Ectopia lentis et pupillae Bilateral displacement of lens and pupil in opposite directions

8 Congenital ectropion uveae Presence of pigment epithelium on the stroma of the iris

High incidence of glaucoma

Systemic anomalies may be present

9 Congenital microcoria and Myopia Results from underdevelopment of dilator pupillae muscle of iris

Associated with goniodysgenesis and glaucoma


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possible to see the fundus with this 50 diopter concave lens

despite significant corneal edema through an undilated pupil.

This is a nongonioscopic use of Koeppes lens.

Gonioscopic Features of PCG23,31

Morning mist appearance.

Disc and Fundus Evaluation

Central, concentric steep walled cup (Fig. 12).

What Type of Refractive Errors are Common inPCG Patients?

Induced myopia

Astigmatism due to irregular scarring.

Pachymetry

IOP in children shows an increasing trend with age,

hyperopia and central corneal thickness (CCT), reaching

adult IOP values by 12 years in a study of the Indian pediatric

population by Sihota.28PCG patients have revealed a trend

towards thinner corneas on ultrasound pachymetry.31Studies

on CCT in PCG however are of preliminary nature and have

not been confirmed.

Determining accuracy of measurement of CCT in edematous

corneas anyhow remains a challenge.

Axial Length (AL)

As a guide to the severity of glaucoma and for follow-up.

Severity Index

A severity assessment on first presentation has been proposed

by Mandal et al in their review of cases (Table 6).32

Surgical Treatment of PCG

For all the practical reasons, buphthalmic eyes are a special

surgical challenge:33-36

Opaque cornea

Distended globe with high IOP

Posterior shift of limbus

Thin sclera and limbus

Thick and active Tenons capsule, rapid wound healing

Lower scleral rigidity

Friable iris

Life long lasting results anticipated

Visual rehabilitation is difficult.

Choice of Surgery

Due to aggressive fibrosis and rapid healing in younger age

groups, conventional filtering surgery enjoys limited long-term

success. Best surgical results are obtained, when surgery is done

as early as possiblebefore the onset of irreversible glaucoma

and secondary changes in the angle and cornea occur.21,35-38The following procedures are listed for their application in

childhood glaucoma.39,40-46

Trabeculectomy with antimetabolites46

Trabeculotomy ab externo47

Combined trabeculotomy with trabeculectomy (CTT) with

or without antimetabolites

Nonpenetrating Schlemms canal resection44,45

Goniotomy50

Glaucoma drainage devices (GDD)

Cyclodestructive procedures.

Trabeculotomy with Trabeculectomy (CTT)

This is the most commonly performed surgery in India. It has

the following clear advantages over goniotomy:39-47

Can be performed in opaque cornea

Familiarity with ab externo approach

Can be combined with trabeculectomy

Satisfactory IOP control.

Principle

To cannulate Schlemms canal from external approach and then

tear through the TM into the anterior chamber, creating a direct

communication between the AC and Schlemms canal.

Additional trabeculectomy is done to enhance long-termsuccess.

History

Burianand Smith independently reported it in 1960 as an

alternative to goniotomy. Harms and Dannhiem modified the

Table 6: Severity index in PCG*18

Clinical parameter Normal Mild Moderate Severe/Very severe

Cornea diameter in mm Up to 10.5 > 10.5-12 > 12-13 > 13

IOP mmHg 11.5 > 11-70 > 10-30 > 30

C:D ratio 0.3-0.4 > 0.4-0.6 > 0.6-0.8 > 0.8 Last BCVA 20/20 < 20/60-20/60 < 20/60-20/200 < 20/400-no PL

*This comprehensive chart may help to provide a realistic approach in management of PCG.

Fig. 12:Central cupping with a pink neuroretinal rim in PCG


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procedure.47Reported success rates vary from 73 to 100%.

Indian studies reported a cumulative success rate of 60% over

a long-term follow-up.33,37

Steps of Combined Trabeculotomy withTrabeculectomy using Intraoperative MMC

Conjunctiva is sutured appropriately, fornix based flap with

two wing sutures (purse string type) and multiple (usually 2-3)

bleb forming sutures with 10-0 nylon. Limbus based flap

requires double layer suturing of the Tenons layer and

conjunctiva. Care is taken to hydrate the side port and titrate

the bleb to ensure water tight closure (Figs 13 to 16).

Intraoperative Complications51,52

Perforation of sclera/false passage

Descemets stripping

Nonlocalization of TMs canal

Severe hypotony after first canulation, so noncanulation onsecond side

Loss of anterior chamber and lens injury

Wrap around iris

Iridodialysis

Cyclodialysis

Hyphema.

Postoperative Complications47,51-58

Chronic hypotony

Shallow anterior chamber

Hyphema

Choroidal detachment

Cataract

Retinal detachment Inadequate IOP control

Blebitis

Endophthalmitis

Long-term effects of antifibrotic agents is not known.

Enhanced astigmatism.

Postoperative Protocol

Topical steroid and cycloplegic drugs are given for a maximum

of six weeks. Cushings syndrome has been reported with

unsupervised topical use of glucocorticoids in infants.48,49

Regular Follow-up

To assess control of IOP

Refraction

Amblyopia therapy

Success may be complete or qualified (on one topical drug)

on the basis of IOP lowering effect54

Optical keratoplasty.

Fig. 13: Globe fixation with two bridle sutures through the episclera on either side of superotemporal quadrant

Fig. 14:Fornix based conjunctival flap dissection


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Alternate Procedures55

360 suture trabeculotomy.

6-0 Prolene suture is used to thread the entire Schlemms canal

and rupture it to communicate with the anterior chamber.

Nonpenetrating Schlemms Canal Resection

In this procedure, a block of tissue is excised beneath the scleral

flap to exteriorize the Schlemms canal without penetrating

the AC. It has been reported to be fairly successful.

Goniotomy50,59

Aim is to transect the Schlemms canal by ab-interno approach.

Historical Aspects

This operation was first done by Carlo de Vincentiis in 1893

without angle visualization. Barkan, later in 1938, under

gonioscopic visualization aimed to cut the Barkans

membrane. However, the concept of Barkans membrane has

not been substantiated. The aim of modern goniotomy is to cut

open the Sclemms canal by slicing through the TM.

Prerequisites

Clear cornea

Age 3 to 12 months preferably

Good visibility of angle structures with clear identification

of meshwork, which is difficult

Technical expertise required

Corneal diameter not >15 mm.

Procedure

A round, dome shaped direct gonioscope is placed on the cornea

with suturing or with a handle (Swan Jacob type). A nontapered

knife or needle enters the AC just inside the limbus and is

withdrawn. Injection of viscoelastic is done to maintain the AC

during the procedure. Re-entry is done with the knife, which

courses in the same plane as the iris. The TM is engaged just

below the Schwalbes line in the opposite quadrant and a

circumferential incision is made across the visible meshwork.

It should be a superficial incision with no grating or scraping

sensation. Prior treatment with pilocarpine eye drops is

recommended. An immediate widening of the angle under view

and posterior movement of the iris, if visible is a definite

indication of success. The knife is withdrawn in a similar fashion

without collapsing the AC. An AC maintainer has also been

used for the same.

Advantages

Good success rate up to 90% between 3 to 12 month

Special role in aniridia to prevent glaucoma.

Fig. 15:Gentle sponge application of MMC 0.02% on the surface for 1-2 minutes and washed copiously

Fig. 16:A 5 5 mm rectangular partial thickness scleral flap in the superotemporal quadrant dissected up to the clear cornea


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Disadvantages

Not possible in opaque cornea

Minimal opacity like Haabs striae can jeopardize

visualization of the angle

Expertise development required

Peripheral anterior synechiae form easily leading to failure.

All the above listed procedures have been modified from time

to time. Some important ones are mentioned here:

Goniotomy with goniopunctureaim is to raise a bleb

Trabeculopunctureaim is direct laser opening of the

Schlemms canal under gonioscopic visualization

Trabeculodialysisaim is surgical scraping of the TM from

the scleral spur.

How is the Surgical Success determined after Anyof these Operations?

The following parameters are to be assessed:21,35-38,41-58

Corneal clarity

A shallow AC is not common in PCG. Transient shallowing

may occur in the first 3 to 4 days after the surgery

Relief of photophobia

Lowering of IOP: An IOP in the low teens is preferable

Bleb: diffuse, pale blebs are seen after using MMC

Reversal or nonprogression of disk cupping

Reversal or nonprogression of myopia

Visual outcome: Good visual recovery, which may be

difficult to document in children.

*Tonometry may be possible under topical anesthesia while

the infant is being fed with the bottle.

*Use of topical or systemic steroids must not be prolongedbeyond 6 weeks.

What is the Status of these Surgeries?

Comparison of CTT with goniotomyCTT is the first choice

because of:

Easy adaptability 57,58

Safe and successful

Suitable even in compromised corneas

More predictable than goniotomy

Goniotomy not suitable for > 15 mm cornea

Higher success rates of primary trabeculotomy than

goniotomy, 83% vs33% in a comparative study.57

Results of Primary CTT53-58

Surgical success has been defined as IOP < 16 mm under GA

or < 21 mm without GA with no progression of cupping or

corneal diameter. Qualified success is defined as maintenance

of this pressure with a single drug (timolol). Extreme hypotony

(< 5 mm) leading to maculopathy has been defined as failure.

Macular hole has been reported following severe hypotony:56

CTT is the preferred choice in Indian patients as 80% present

with severe corneal clouding and are anyway not suited for

goniotomy. Encouraging reports from Indian authors in large

series of PCG cases add to the credibility of the procedure.Mandal AK et al have published several reports on the high

success and safety profile of combined trabeculotomy and

trabeculectomy in PCG even in very small infants. The

authors were confident to perform this procedure

simultaneously in newborn patients with bilateral glaucoma

under one month of age with no complication, reporting a

success rate of 94.4% by Kaplein Mayor analysis in 182

eyes of patients.59Bilateral simultaneous surgery is, however

not a universally accepted practice. Good visual recovery

was reported in another study on advanced glaucoma

children with corneal diameter of 14 mm or more.18No

sight threatening intra- or postoperative complications were

noted in any of the patients.

In a series of 61 eyes with PCG, Dietlein36however reported

the need for resurgery in 1/3rd of their cases in 36 months

of median follow-up with no decrease in the number of

glaucoma medications.

British infantile glaucoma (BIG) I study in a prospective

analysis of 99 recently diagnosed cases of pediatricglaucoma patients reported < 21 mm IOP in 94% with

medication, 60% without any glaucoma medication in the

primary congenital group as compared to 86% with and

28% without glaucoma medication in the secondary

glaucoma group.5

The success criteria chosen by different authors do not

match, variable IOP levels at 21 mm, 18 mm and 16 mm

have been taken as indicators of successful control.54,55

Results of Re-surgery

Trabeculectomy with mitomycin C (MMCT) has a moderate

probability of success ranging from 36 to 95%, with lower

success seen in younger children. Though this pharmacologic

modulation does control IOP in refractory pediatric glaucoma,

the procedure seems to have a higher risk profile with no

additional IOP lowering effect in a retrospective study of 61

patients in 19 years of follow-up by Rodriques.67Mandal in

1997 reported complete success in 94.74% of complicated

glaucoma inclusive of failed secondary glaucomas. One patient

had qualified success and one patient had retinal detachment

which is a rare association for which cause could not beascertained.20 Fluorouracil (5FU) as a single intraoperative

application has shown uniformly poor efficacy in children for

controlling glaucoma.41

Management of Failures, Residual and

Refractory Glaucoma

Medical Therapy

It is an established fact that best outcome is after first successful

surgery.54 Each time surgery is repeated, success rate is likely

to drop. Following guidelines are recommended: Stop steroids: oral/topical

Start on topical beta-blockers and CAI


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JOCGP

Prostaglandin analogues have to be avoided in unilateral

cases due to hyperpigmentation and hypertrichosis of lashes.

Alpha 2 agonists are not recommended in children below

two years of age.

Oral CAI have been reported to produce additive effect with

topical drugs same in children but still long-term use is not

advisable.

Glaucoma Drainage devices in Children

Glaucoma drainage devices (GDD) offer a promising

alternative in such conditions. Quoting Albert W Biglan

(Costenbader Lecture, 2006) Success in treatment of

primary infantile glaucoma will be determined by the age

of onset and the ability to deliver a safe and effective

procedure.11 Several glaucoma procedures and devices

have been attempted to fulfil this adage.

In an initial clinical experience with Ahmed glaucoma valve

(AGV) in 21 pediatric patients, Coleman has reported

similar success as other GDD up to 77.9% at 12 monthsand 60.6% at 24 month.65In another comparative study, 38

eyes of complicated pediatric glaucoma were studied in two

groups, 20 had MMCT and 18 had AGV implantation.52

Comparisons drawn in the complication rates between

MMCT and AGV are given in Table 7.

Glaucoma Drainage Devices

These are broadly divided into two types:

Nonvalved/nonrestrictive

Molteno

Baerveldt

Schocket.

These rely on the formation of a fibrous bleb that is formed

on the endplate. This fibrous capsulation provides resistance to

outflow. Amount of outflow depends on the surface area of the

implant encapsulation and the capsular thickness. The non-

valved implants have a higher incidence of postoperative

hypotony. Either two stage surgery to implant the plate first

followed by 2nd stage tube implantation or a flow restrictive

suture in the initial postoperative period is recommended to

prevent hypotony.

Valved/flow restrictive

Ahmed

Krupin

Joseph

Optimed.

Valved implants have an internal mechanism to control the

outflow of the aqueous. Therefore, the fluid is not able to drain

unless a minimum IOP is reached. Once the threshold IOP is

reached, the device allows aqueous humor to flow. The valved

devices prevent hypotony.

Implants used in Pediatric Cases

Non-valved

Molteno: This was the 1st aqueous shunt to gain widespread

acceptance, with the initial model being released in 1976. It

can be single or double plate.

Baerveldt: This flexible elliptically shaped silicone rubber

device is available in three plate sizes 250/350/500 mm. The

current version has been modified with the introduction of

fenestrations to encourage tissue ingrowth.

Valved implants: Ahmed glaucoma valve (AGV) has been in

use for adults and children. The newer all silicon models have

shown more encouraging and improved results. The authors

experience in GDD is confined to AGV and the same will be

presented here.

Ahmed Glaucoma Valve (AGV)

Specifications of Pediatric Model of AGV

Surface area of plate96 mm2

Tube outer diameter0.635 mm

Tube inner diameter0.305 mm

When the IOP rises (8-12 mmHg), the valve opens, thus

letting fluid flow out of the eye through the drainage tube. The

valve automatically closes when the pressure is normal again.

Aqueous humor from AC of the eye flows through the tube into

the trapezoidal chamber within the plate element. This chamber

Table 7: Comparisons in complication rates between Ahmed glaucoma valve (AGV) and trabeculectomy with mitomycin C (MMCT)

AGV(%) eyes MMCT(%) yes

Tube extrusion 5 0

Reposition of tube 5 0

Shallow AC Transient: 10 Reformation: 14

Choroidal hemmorhage Limited: 10 Massive: 5

Corneal blood staining 5 10

Scleral graft thinning 5 0

Choroidal detachment: drainage 0 5

Aqueous misdirection 0 5

Corneal decompensation 0 10 Lenticular opacity 0 29

Total no. of patients = 38, MMCT = 20, AGV = 18.


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Usha Yadava

68JAYPEE

is formed by a folded-over silicone elastomer membrane with

its free edges forming a one way valve.

Accessories

Tube extender and tube holding forceps.

In the rare event of tube retraction with the growth of theeye, tube extension is possible using the extender. Adjunctive

tissue may be needed for better tube stability and to prevent its

exposure. Use of the following materials has been reported in

literature: pericardium, sclera, fascia lata and amnion.

Indications in Pediatric Glaucoma63,65,70,71

Failed glaucoma surgery

Failed medical control after surgery

Pseudophakic/aphakic glaucoma

Secondary glaucoma

Complicated PCG

Neovascular glaucoma.

Steps of AGV Implantation

Postoperative Treatment

Topical steroids and cycloplegia as in any other intraocular

surgery.

Advantages of GDD (Valved)67-71

Avoids the risk of a thin avascular filtering bleb.

Ciliary body function is preserved.

Safer surgery in large buphthalmic eyes.

How to Maximize Results of AGV

Conjunctiva should be adequate

Two episcleral bridle sutures; on either side of proposed

site

Must prime the valve

Subscleral tube insertion

Use only 23G needle for entry into AC

Do not hold implant at the trapezoid chamber

Use atraumatic forceps for holding tube

Introduce tube bevel up and in iris plane

Water tight conjunctival closure

Patch graft over the tube prevents late exposure.

Complications

Tube migration/retraction with

Diplopia

Tube exposure/extrusion

Posterior Tenons cyst

Tube blockage

Endothelial decompensation

Hypotony Infection

Failure to control IOP

Corneal blood staining

Shallow AC

Scleral flap thinning

Choroidal detachment

Aqueous misdirection.

Brief Summary of Clinical Trials inPediatric Glaucoma

Earliest reported use of glaucoma drainage implants in pediatric

glaucomas dates back to 1970 by Molteno in eyes with

inadequately controlled IOP despite previous glaucoma

surgery.66-71

Dietlein et al performed different types of ab externo

procedures in 61 eyes of 35 consecutive patients of PCG.

20 of 61 eyes (1/3) needed a resurgery at 36 months of

median age.36

In 149 eyes of 89 patients of development glaucoma, Ikedaet al reported complete success in 63.4% (71 eyes) and

qualified success in 25.9% (29 eyes). Best corrected visual

acuity of > 20/40 was observed in 59.5% (78 eyes). Age

< 2 years was found to be associated with poor prognosis

and needed more interventions.58

Englert et al found devastating complications in 20 eyes

treated by MMCT as against 5% in the GDD treated group.

Higher rate of complications like cataract and infections

has prompted some surgeons to look to GDD as a favorable

option especially in resurgery cases.70

Beck and associatesreported a success rate ranging from

87% in one year to 53% in six years of follow-up in children

< 2 years of age. They also noted that drainage implantation

provides a greater successful control as compared to

MMCT. A relatively lower success rate of 36% was noted

in the MMCT.69

Armenian eye care project: 38 eyes of 34 patients underwent

either MMCT (20) or Ahmed valve (18) with a mean age

of 12.5 years for a variety of glaucomas, including secondary

glaucomas. The AGV group was twice as likely to use

postoperative ant iglaucoma medication compared to

MMCT44% and 23% respectively. A remarkable drop

of 3 lines in visual acuity mostly due to onset of cataract inthe MMCT group was observed in 28% compared to 12%

in the AGV group (p value < 0.05%). Total success rate

was comparable in the two groups at 13.5 vs 14.8 mmHg

(p value < 0.05%).67

Overdam et al studied the role of Baerveldt implant in

55 eyes of 40 patients < 16 years of age out of which 35

patients had congenital glaucoma. Baerveldt (350 mm2)

implantation was performed. Surgical outcome was

evaluated by Kaplan-Meier table analysis. The overall

success rate was 80% at last follow-up,with a mean follow-

up of 32 (range 2-78) months. Cumulativesuccess was 94%

in 12 months and 24 months, 85% in 36 months,78% in 48months, and 44% in 60 months. 11 eyes (20%) failed

postoperatively because of an IOP >21 mmHg (eight eyes),


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JOCGP

persistent hypotony (two eyes), and choroidal hemorrhage

followingcataract surgery (one eye). The most frequent

complication needingsurgery was tube related (20%). A

new observation was mild tomoderate dyscoria in 22% of

the eyes, all buphthalmic, causedby entrapment of a tuft of

peripheral iris in the tube track. The BGI is effective and

safe in the managementof primary and secondary glaucoma.

When angle surgery has proved to be unsuccessful or

inappropriate in pediatric patients,a BGI is a good treatment

option. One must be prepared to dealwith the tube related

problems.68

Another implant was introduced by Sussanain Brazil, which

combined the features of both Molteno and Baerveldt

implants. These implants were studied in 24 children of

primary congenital glaucoma with uncontrolled IOP despite

previous surgery. A success rate of 87.5% was noted at the

end of 1 year.71

In summary, it appears that valves do have a place inpediatric glaucoma, though so far most reports are on patients

with failure of prior surgery. It may be speculative to presume

that results would be better in primary cases, where the tissues,

especially conjunctiva, are well preserved. Preliminary evidence

does support the need for a controlled trial of GDD as against

the prevalent CTT in this subset of glaucoma.

Role of Cyclodestructive Procedures

Trans-scleral cycloablation with Nd-YAG or diode has been

used safely in children and seems to have a palliative and

temporizing effect. Lower settings than adults are

recommended as these children have thin sclera.

Cyclocryotherapy has a significant risk of hypotony and

recommended in eyes with low vision potential and

cosmetically disfiguring eyes with high IOP only.

Role of Optical Keratoplasty105

Higher chances of graft failure

Suture infections in pediatric age

Arduous follow-up.

Prognosis of Childhood Glaucomas

These factors emerge decisive:

The severity of the disease

Age of onset and intervention

Number of surgeries

Timely and sustained control of IOP

Residual corneal scarring, anisometropia and astigmatism

Aggressive treatment of amblyopia.

Glaucoma in children presents a vexing problem. These,

patients are often brought in late, firstly due to the ignorance of

parentsand secondly inadvertent delay caused by indecision

on the part of the attending physician. To make matters worse,

relative unfamiliarity with the condition extracts an arbitrary

approach at the level of primary care, which further adds to the

woes of the patients and soon all vision may be lost forever.

Undoubtedly, the issues of timely diagnosis, techniques in

children and parental motivation are some of the problems.

To sum up, it seems that surgical results are very case and

surgeon specific depending on their experience in case selection

and choosing the appropriate procedure. The time is now right

to let go of the old dogmas and letting in the new. Let us join

hands, organize newer multicentric control trials in childhood

glaucomas as the disease is a special concern of the ethnic

groups.

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