Rhegmatogenous retinal detachment (RRD)

DR. PAVAN S. MAHAJAN

Retinal detachment

• A Retinal Detachment (RD) describes the separation of the neurosensory retina (NSR) from the retinal pigment epithelium (RPE).

• Rhegmatogenous• Tractional• Exudative• Combined

Rhegmatogenous retinal detachment (RRD)

• full-thickness defect in the sensory retina, which permits fluid derived from synchytic (liquefied) vitreous to gain access to the subretinal space.

• Even if a retinal break is present, a RD will not occur if---

vitreous is not at least partially liquefied and if the necessary traction is not present.

• RRD is usually preceded with posterior vitreous detachment(pvd)

• Retinal detachment without PVD is usually associated with either retinal dialysis, or round holes predominantly in young female myopes.

Posterior vitreous detachment

• Synchysis• Hole in posterior hyaloid membrane.• Newly formed retrohyaloid space.• Acute pvd

Complications of acute PVD

• NO COMPLICATION

• RETINAL TEARS

• AVULSION OF PERIPHERAL BLOOD VESSEL

Pathogenesis• Dynamic vitreoretinal traction

• Predisposing peripheral retinal degeneration

• Break - full-thickness defect in sensory retina• Hole - caused by chronic retinal atrophy• Tear - caused by dynamic vitreoretinal

traction

Quadratic distribution of breaks in eyes with RD

Vitreous adhesions1 Normal . The peripheral cortical vitreous is loosely attached

to the internal limiting membrane (ILM) of the sensory retina. Stronger adhesions occur at the following sites:

Vitreous base, where they are very strong. Around the optic nerve head, where they are fairly strong. Around the fovea, where they are fairly weak, except in

eyes with vitreomacular traction and macular hole formation.

Along peripheral blood vessels, where they are usually weak.

Vitreous adhesions2 Abnormal adhesions at the following sites may be

associated with retinal tear formation as a result of dynamic vitreoretinal traction associated with acute PVD.

Posterior border of islands of lattice degeneration. Retinal pigment clumps. Peripheral paravascular condensations. Vitreous base anomalies such as tongue-like extensions

and posterior islands. ‘White with pressure’ and ‘white without pressure’.

Predisposing peripheral retinal degeneration

• 60% of all breaks develops in peripheral retina

Lattice degeneration

• More commonly in moderate myopes and is the most important degeneration directly related to RD.

• Laterality- bilateral• Location: Commonly -temporal superiorly fundus. • 40% of eyes with RD.

Pathology Discontinuity of internal limiting membrane Atrophy of the underlying NSR. Vitreous - Overlying an area of lattice is synchytic -attachments around the margins are exaggerated

3 Signs Spindle-shaped areas of retinal thinning between the equator and the posterior border of the

vitreous base. • Arborizing network of white lines within the islands • Associated with ‘snowflakes’ (remnants of degenerate Müller cells. • Associated hyperplasia of the RPE is common . • Small holes within lattice lesions are common and usually innocuous

Small island of lattice with an arborizing network of white lines; lattice associated with ‘snowflakes’;

lattice associated with RPE changes

Complications of lattice degeneration

Snailtrack degeneration

• Sharply demarcated bands of tightly packed ‘snowflakes’ - white frost-like appearance.

• longer islands than in lattice degeneration • Associated with overlying vitreous liquefaction• Vitreous traction at the posterior border of the

lesions is seldom present so that tractional U-tears rarely occur,

• Round holes within the snailtracks may be present

White with pressure’

• Translucent grey appearance of the retina - indenting the sclera.

• In normal eyes• Associated with abnormally strong attachment

of the vitreous gel• Along the posterior border of islands of

degenerations.

‘White without pressure’ • Without scleral indentation. • Mistaken for flat holes.• Giant tears occasionally develop along the posterior border • For this reason, if ‘white without pressure’ is found in the

fellow eye of a patient with a spontaneous giant retinal tear, prophylactic therapy should be performed

• 360° cryotherapy / indirect argon laser photocoagulation, irrespective of the presence of ‘white without pressure’, if they have not developed a PVD.

Primary retinal break

Configuration of SRF in relation to primary break

Rhegmatogenous RD

• Fresh• Longstanding• Proliferative vitreoretinopathy (PVR)

Fresh Retinal detachment

• 1. The RD has a convex configuration and a slightly opaque and corrugated appearance as a result of retinal oedema

Loss of the choroidal pattern Retinal blood vessels - darker than in flat retina

2. SRF extends up to the ora serrata

3. B-scan ultrasonography shows good mobility of the retina and vitreous

Long-standing retinal detachment

• Frequently inferior with small holes• Very thin retina• Secondary intraretinal cysts

Long-standing retinal detachment

• Subretinal demarcation lines (‘high water marks’) caused by proliferation of RPE cells at the junction of flat and detached retina

Proliferative vitreo-retinopathy

• The term "proliferative vitreoretinopathy" was coined in 1983 by the Retina Society Terminology Committee.

• In 1989, the classification was amended by the Silicone Study Group before being most recently modified in 1991 to its current classification.

• Currently, PVR is divided into grades A, B, and C.

Grade A (minimal)• Vitreous haze and tobacco dust

Grade B (moderate)• Retinal wrinkling and stiffness• Rolled edges of tears

Grade C (severe)• Rigid retinal folds• Vitreous condensations and strands

Symptoms

• 1 Photopsia• 2 Floaters• a Weiss ring • b Cobwebs• c A sudden shower of minute red-coloured or

dark spots usually indicates vitreous haemorrhage• 3 A visual field defect is perceived as a ‘black

curtain’.

Signs:

• Marcus gunn pupil• Low IOP relative• ‘Tobacco dust’[shafer’s sign]• Retinal breaks• Mild iritis

Management

• Scleral Buckling

• Pneumatic retinopexy

• Primary pars plana vitrectomy (with or without sclera buckling)

Asymptomatic retinal detachment

• range from conservative observation to prophylactic surgery.

• demarcation laser photocoagulation of shallow, macula-sparing, RRD without associated PVR to be a reasonable alternative to surgical repair.

CHOICE

• individual clinical situation combined with each surgeon's experience bias and comfort level with a particular procedure.

• Without a randomized clinical trial comparing the 3 modalities, and in various clinical scenarios, definitive answer as to which procedure is superior will be impossible.

Basic Rationale of repair of RRD ---

• The regardless of the procedure chosen, the surgery aims to identify and close all the retinal breaks with minimum iatrogenic damage.

Break closure

1)to bring the edges of the retinal break into contact with the underlying RPE –

• by bringing the eye wall closer to the detached retina (a scleral buckle)

• pushing the detached retina toward the RPE (intraocular tamponade with a gas/ PFCL expand bubble).

2)to create a strong chorio-retinal adhesion around the breaks;

• cryotherapy, • laser photocoagulation• diathermy.

Scleral Buckling:

• Scleral buckling surgery has been considered as the “gold standard” for uncomplicated RD, despite recent trend toward pars plana vitrectomy.

• More recently, European VitreoRetinal Society RD Study Group has shown significantly higher final failure rate with vitrectomy with or without buckle as compared to scleral buckle alone in uncomplicated RD in phakic eyes, but no significant difference in pseudophakic eyes

At least three mechanisms:

1. The procedure directly offsets antero-pesterior vitreous traction along the surface of the buckle;

2. The buckle displase the retinal break centrally, where the break becomes tamponaded by cortical vitreous, preventing further flow of fluid through the break;

3. The buckle displaces subretinal fluid away from the break and alters the shape of eyewall, thus reducing the effects of the intraocular fluid currents.

Scleral Buckling:

They are made of solid silicone and silicone sponges. These elements are affixed to the episcleral

surface with 5.0 polyester or nylon or passing the elements through small lamellar scleral tunnels.

Can be used as – as explants or as implants.

• Explants most commonly done procedure where the buckle is sutured to the sclera.

• Implant – they are placed in the bed of the dissected

sclera.

Ecircling exoplant

Multiple breaks;Aphakic or pseudophakic eyes;High myopia; Extensive areas of lattice degeneration;PVRGiant tearsEyes with very thin sclera.

Segmental circumferential buckles closely spaced retinal breaks without the

presence of other retinal pathology.

Radial exoplants Large horseshoe tears;Relatively posterior tears.

Steps

• -conjunctival peritomy and tenotomy• - Isolation of the recti muscles.• - Localisation of breaks with IDO• - Retinopexy with Cryotherapy /laser

photocoagulation• - Suture placement / scleral bed dissection

and placement of buckle is then performed.

• -Subretinal fluid drainage is done based on surgeon preference and case based need.

• - Break buckle relation and adjustment of buckle height,

• - Careful monitoring of central retinal artery perfusion is done (AC Paracentesis done if required)

• - Finalisation of buckle and encirclage• - Closure of the conjunctiva

a) Cryotherapy vs laser photocoagulation

• In a randomised clinical trial by Lira et al in eighty six patients with uncomplicated retinal detachment, both techniques of retinopexy were shown to have satisfactory anatomical and functional success.

• Laserpexy offered faster visual acuity recuperation with fewer postoperative Complications but required a second intervention and was costlier than cryotherapy.

• laserpexy is considered as a successful alternative to cryopexy in creating chorioretinal adhesion for scleral buckle surgery

b) Need for drainage of subretinal fluid?

• Drainage of subretinal fluid is one of the debatable issues in scleral buckling.

• As this step is almost a blind procedure it is not free from potential complications that include

choroidal hemorrhage, retinal incarceration and intraocular infection.

• Drainage in scleral buckling surgery is usually done in bullous detachments to visualise the breaks, to make space to allow a large scleral indent without significant increase in intraocular pressure.

• drainage of subretinal fluid is not an absolute necessity and is indicated only in specific situations.

methods of drainage

• 1) Scleral cut-down and choroidal puncture with diathermy,

• 2) Scleral cut-down and the choroidal puncture by argon laser via an indirect ophthalmoscope or endoprobe.

• 3) Needle drain where the sclera and choroid are punctured in one stab with a 3 mm suture needle• 4) Needle drainage with 26/27 g needle

Complications of scleral buckling

• Dislocation of buckling elements;• Scleral perforation in about 5% of cases;• Anisometropia- encircling elements may induce

an average of approximately 2D of myopia;• Strabismus;• Vortex veins could be compressed, possibly

leading to choroidal detachment and IOP elevation.

• The presence of suture material is associated with the risk of buckle infection, which may in turn result in buckle extrusion.

Advantages of sutureless scl. Buckle over sutured buckle

• Inadvertent scleral perforation is avoided

• Suture related buckle infection and extrusion is avoided.

Disadvantage of sutureless scleral buckle over sutured one

• It is difficult to relocate the buckle to a new area, if buckle location is found inappropiate after SRF drainage.

• One needs to convert into regular sutured buckle.