Retinal detachment




Definitions





  • Retinal detachment (RD): separation of the neurosensory retina (NSR) from the RPE, with the accumulation of subretinal fluid (SRF).



  • Rhegmatogenous RD: occurs when a full-thickness defect in the NSR permits synchytic (liquefied) vitreous to gain access to the subretinal space.



  • Tractional RD: involves the contraction of vitreoretinal membranes in the absence of a retinal break.



  • Exudative RD: SRF is derived from retinal or choroidal vessels (e.g. inflammation, tumour).



  • Retinal break: full-thickness defect in the NSR, either (a) a tear, caused by dynamic vitreoretinal traction, or (b) a hole, caused by chronic retinal atrophy.



  • U-tear: consists of a flap with the apex pulled anteriorly by adherent vitreous, the base attached to the retina ( Figs. 16.1a–16.1c ).




    Fig 16.1



  • Operculated tear: flap has been completely torn away from the retina ( Fig. 16.1d ).



  • Dialysis: circumferential tear along the ora serrata with vitreous gel attached to its posterior margins ( Fig. 16.1e ).



  • Giant tear: involves 90° or more of the NSR ( Fig. 16.2 ).




    Fig 16.2





Rhegmatogenous retinal detachment





  • Pathogenesis: rhegmatogenous retinal detachment (RRD) affects approximately 1 in 10,000 of the population each year; both eyes are eventually involved in approximately 10%. Presentation is typically between 45 and 65 years of age but may be earlier, especially if predisposed (e.g. myopia).




    • Posterior vitreous detachment (PVD): (a) separation of the cortical vitreous from the internal limiting membrane (ILM) of the NSR posterior to the vitreous base with the remaining solid vitreous gel collapsing inferiorly (acute PVD; Figs. 16.3a and 16.3b ), (b) some eyes with acute PVD develop retinal tears ( Fig. 16.3c ), and subsequent RRD; (c) occasionally avulsion of a peripheral blood vessel may cause vitreous haemorrhage without a retinal tear ( Fig. 16.3d ).










      Fig 16.3



    • RRD without PVD: usually associated with a retinal dialysis or round holes.



    • Lattice degeneration: present in approximately 8% of the population and in approximately 40% of eyes with RRD: (a) spindle-shaped islands of retinal thinning with a characteristic network of white lines, (b) associated RPE hyperplasia; (c) small holes within islands are common ( Figs. 16.4a–16.4d ); (d) overlying gel is liquefied, but its adhesions around the margins of lattice are exaggerated ( Fig. 16.5 ); (e) tears typically occur at the posterior edge of an island.




      Fig 16.4



      Fig 16.5



    • Snailtrack degeneration: (a) sharply demarcated peripheral bands of tightly packed ‘snowflakes’ (see Fig. 16.4e ), (b) small holes; (c) overlying vitreous is liquefied but marked adhesions are seldom present so that tears are less common than in lattice.



    • Degenerative (acquired) retinoschisis: (see Fig. 16.4f and below).



    • White with pressure’: translucent grey appearance of a region of retina induced by indenting the sclera that may be associated with abnormally strong vitreous attachments.



    • ‘White without pressure’: same appearance without scleral indentation ( Fig. 16.4g ).



    • Significance of myopia: more than 40% of all RRDs occur in myopic eyes; (a) macular holes may give rise to RRD in highly myopic eyes, (b) vitreous loss and laser posterior capsulotomy are more likely to lead to RRD than in non-myopic eyes, and (c) predisposing factors are more common in myopic eyes (vitreous degeneration, PVD, lattice and snailtrack degenerations).



    • Other predisposing lesions: (a) pigment clumps (see Fig. 16.4h ), (b) diffuse chorioretinal atrophy (see Fig. 16.4i ), and (c) abnormal paravascular vitreoretinal adhesions (see Fig. 16.4j ).




  • Degenerative (acquired) retinoschisis


Jul 11, 2019 | Posted by in OPHTHALMOLOGY | Comments Off on Retinal detachment
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