VASCULAR AND HEREDITARY RETINAL DISEASE

DISORDERS OF THE VITREOUS AND RETINAL DETACHMENT Dr Russell J Watkins

Vitreous Virtually acellular Viscous Collagen framework, reinforces with hyaluronate 98% water; volume = 4.5ml in emmetropic eye Condensations of vitreous Anterior hyaloid membrane Posterior hyaloid membrane Tracts in gel Cloquet’s canal

Vitreous Attachments of vitreous Vitreous base Strong, 3-4mm annular attachment, extending across ora serrata Weigert’s ligament 8-9mm annular attachment to posterior lens surface (anterior end of Cloquet’s) Vitreopapillary adhesions Posterior end of Cloquet’s canal  Weiss ring Vascular adhesions (hence bleeds with PVD) Areas of vitreoretinal degeneration e.g. lattice degeneration, cystic retinal tufts

Vitreous Aging changes Dissociation of hyaluronate from fibrils Pooling of hyaluronate Fibril degeneration &  elasticity Drainage of hyaluronate into retrovitreal space (  posterior vitreous detachment [PVD])

Vitreous Opacities Muscae volitantes: remnants of hyaloid system Syneresis Weiss ring Haemorrhage Tobacco dust: pigment cells Inflammatory cells Pars planitis Chorioretinitis AC spillover

Vitreous Opacities Synchisis scintillans (settles inferiorly with rest) Asteroid hyalosis Seen in 1:200 eyes; more common in DM Ca 2+ -soaps, adherent to fibrils Does not settle at rest Neoplastic cells Amyloid

Vitreous Vitreous degeneration Syneresis Vitreous liquefaction, fibril aggregation & condensation Associated with floaters Caused by myopia, senescence, trauma, inflammations, hereditary causes Posterior vitreous detachment

Posterior Vitreous Detachment Collapse of vitreous gel Associated with photopsia & floaters Causes Senile Myopic Post-inflammatory Post vitreous haemorrhage Diabetes mellitus Read Chignell et al (2000) Optometry in Practice 2(1);97 et seq

Posterior Vitreous Detachment PVD with gel collapse Without vitreous haemorrhage, 4% develop retinal breaks With vitreous haemorrhage, 20% develop breaks PVD without gel collapse Associated with future retinal hole or vitreous haemorrhage Scaffold for proliferative new vessels

Vitreous Haemorrhage Proliferative retinopathies DM Retinal vein occlusion Sickle cell retinopathy ROP Eale’s disease PVD Trauma

Vitreous Haemorrhage Disciform macular degeneration Blood dyscrasias Subarachnoid haemorrhage (Terson’s syndrome) Complications of vitreous haemorrhage Syneresis; Fibrosis  traction RD; Haemosiderosis; Haemolytic (ghost cell) glaucoma; Synchisis scintillans; Ochre membrane

Retinal Detachment Retinal detachment can be: Rhegmatogenous Tractional Exudative

Rhegmatogenous RD RD occurring in association with hole formation; incidence 1:10,000 per year Predisposing conditions Acute PVD Myopia (esp. High myopia)  Age Trauma Aphakia (1% of ICCE; 0.1% of ECCE with intact PC) Vitreoretinal degenerations

Rhegmatogenous RD Pathogenesis Following PVD, dynamic vitreoretinal traction occurs at abnormal adhesions This can  vitreous haemorrhage Traction  energy transmission to retina To relieve traction, a break forms RD caused by collection of subretinal fluid

Rhegmatogenous RD Pathogenesis Sensory retina detaches from RPE Pigment cells may be avulsed into vitreous  tobacco dust This predisposes to proliferative vitreoretinopathy (PVR) Retina becomes opaque due to oedema  Photoreceptor degeneration

Types of Break Horseshoe or U-shaped tear Atrophic hole Operculated Dialysis Involves splitting of vitreous base Usually inferotemporal Can be spontaneous or traumatic Macular hole Idiopathic; myopia; Commotio retinae

Types of Break Giant retinal tear 90-360° tear; may fold back Associated with PVR Trauma; myopia; Stickler’s syndrome Bucket handle tears Usually superonasal Avulsion of vitreous base Always traumatic

Rhegmatogenous RD Symptoms Photopsia Floaters Shadow 60% of patients with RD have ALL symptoms

Rhegmatogenous RD Examination VA Visual fields Peripheral retinal evaluation BIO + 3-mirror Tobacco dust Mild anterior uveitis Low IOP

Rhegmatogenous RD Natural history Progression to total detachment Spontaneous reattachment (can happen) Retinal & RPE atrophy “ High water mark” - RPE hyperplasia Viscous subretinal fluid Intraretinal cyst formation PVR Rubeosis iridis Phthisis bulbi

Rhegmatogenous RD Principles of treatment Localisation & closure of breaks Relief of vitreoretinal traction Buckling or vitrectomy Neuroretinal-rpe adhesion Photocoagulation or cryotherapy Internal tamponade Air; longer acting gases [SF 6 , C 3 F 8 ]; Silicone oil

Complications of RD Surgery Anterior or posterior segment ischaemia Infection Perforation or erosion of plomb into eye Extrusion of plomb Muscle imbalance Refractive changes Macular pucker Cataract Glaucoma Redetachment

Vitreoretinal Degenerations Predisposing to RD Lattice degeneration - present in 40% of RD Snail track degeneration “ White without pressure” Benign “ White with pressure”; Pigment clumping; Diffuse chorioretinal atrophy; Peripheral microcystoid changes; Snowflake degeneration; Pavingstone degeneration; Honeycomb degeneration; Drusen; Oral pigmentary degeneration

Tractional RD Penetrating ocular trauma Proliferative retinopathies DM Sickle cell retinopathy ROP Retinal vein occlusion Eale’s disease Persistent hyperplastic primary vitreous Toxocariasis Pars planitis

Exudative RD Uveitis e.g. Vogt-Koyanagi-Harada syndrome Choroidal tumours Malignant melanoma Metastatic Low blood protein levels Hypertension Eclampsia Hypothyroidism Choroidal effusion syndrome

Retinoschisis Splits or cysts within the neurosensory retina Retinoschisis can be Primary Senile (level of OPL) Juvenile/congenital (level of RNFL) Secondary to other conditions

Senile Retinoschisis Bilateral in 33% Usually inferotemporal Usually hypermetropic Dome elevation of inner retinal layers White dots (snowflakes) on inner limiting membrane Inner leaf has beaten metal appearance Sheathing of peripheral vessels

Senile Retinoschisis Round holes can occur in inner leaf Larger holes can occur in outer leaf 1% progress to rhegmatogenous RD Peripheral field defect though often asymptomatic Need periodic observation with visual fields

Juvenile Retinoschisis X-linked recessive Splits in NFL Bilateral Foveal (cystoid changes BUT not CMO) or peripheral Associated with Favre-Goldmann & Wagner’s diseases Poor visual prognosis Predisposes to RD, esp inferotemporally

Juvenile Retinoschisis Present with  vision (may be vitreous haemorrhage) Maybe asymptomatic Even though congenital, may not be detected for years

Secondary Retinoschisis Proliferative retinopathies Trauma Vitreous traction

VASCULAR AND HEREDITARY RETINAL DISEASE

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