Peripheral Retinal Degenerations

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Peripheral Retinal Degenerations


Classification of Peripheral Retinal Degenerations

Peripheral retinal degenerations are classified according to the following criteria:

  • Location- equatorial, peripheral, or combined
  • Pathomorphology- trophic, tractional, atrophic, or combined
  • Depth of retinal changes- intraretinal, retinal, vitreoretinal, or chorioretinal
  • Risk for retinal detachment
  • Prognosis – progressive or stationary

The following are the commonly used classifications of peripheral retinal degenerations based upon depth of retinal changes observed on optical coherence tomography (OCT):

  • Intra-retinal Degenerations: senile retinoschisis, white-without-pressure, white-with-pressure, dark-without-pressure, peripheral cystoid degeneration, snowflake degeneration, and pearl degeneration
  • Vitreoretinal degenerations: lattice degeneration, snail-track degeneration, retinal tufts, and peripheral retinal breaks
  • Chorioretinal degenerations: paving stone degeneration and peripheral retinal drusen

Utility of OCT in diagnosis

Optical coherence tomography (OCT) has been shown to greatly benefit in the diagnosis of peripheral retinal degenerations by characterizing structural elements. Such detail includes the structure, shape and depth of retinal degenerations. Peripheral OCT may further aid in differentiation between types of peripheral retinal degeneration as well associated complications including subclinical retinal detachment, retinoschisis, retinal tears and vitreoretinal adhesions or tractions. Therefore, OCT should be utilized in the initial diagnosis, treatment, and follow-up for peripheral retinal degenerations.  

Intra-Retinal Degenerations

Senile Retinoschisis

  • Definition: senile retinoschisis (SR) is the splitting of layers of the neurosensory retina by thick fluid.
  • Prevalence: found in 2-7% of the general population, more common in patients 40 years and older and in hyperopic eyes
  • Characteristics: Lesion is a bullous elevation of peripheral retina, found in temporal segment
  • Findings: Mostly asymptomatic
  • Immobile with movement of eye and produces an absolute field defect
  • Complications: may involve posterior pole, may lead to retinal detachment
  • Primary cause of retinal detachment in 0.05-2.5% of cases
  • Diagnosis: OCT findings include intraretinal hyporeflective cavities with destruction and thickening of the RPE
  • Treatment: should be treated when patients are symptomatic, or there is progressive retinal detachment threatening the macula

White-Without-Pressure

  • Definition: Distinctive white appearance of the peripheral retina without indentation and without mechanical stimulus
  • Prevalence: found in up to 30% of normal eyes, often bilateral, more frequently diagnosed in younger patients, may be associated with longer axial length
  • Characteristics: Whiter than the retina in white with pressure and the choroidal markings are almost obscured, found in post-equitorial region at the base of the vitreous and ora serrata, whiteness further accentuated with scleral depression, margins are sharply demarcated from normal retina
  • Exact cause is unknown one school of thought states it to be a manifestation of peripheral vitreous traction while one believes it to be simply an abnormal reflex from a structurally normal VR interface
  • Frequently causes confusion with subclinical RD and Retinoschisis but indentation clearly reveals that retina is still apposed to the RPE.
  • Diagnosis: OCT shows white areas correspond to hyperreflective outer retinal layers and ellipsoid zone, no vitreous traction
  • Treatment: low risk for association with retinal detachment, so patients are examined every 1-2 years  

White-With-Pressure

  • Definition: Distinctive milky white or opalescent appearance of the peripheral retina that is observed in many normal eyes when examined with scleral depression
    • Must be carefully distinguished from a subclinical peripheral RD
  • Findings: retina appears normal without depression
    • Infero-nasal quadrant least likely to be affected
  • Prevalence: seen in around 30 to 35% of eyes examined with scleral depression
    • Incidence increases with age, no sex predilection
  • Complications: benign condition, not associated with retinal breaks

Dark-Without-Pressure

  • Definition: flat, brown fundus lesion with well-defined margins in the equator of peripheral retina  
  • Findings: can be found posterior to area of white-without-pressure and may look like retinal tear, posterior to ora serrata
  • Symptoms: usually none
  • Diagnosis: OCT findings show hyporeflectivity of the ellipsoid zone
  • Treatment: usually benign, follow patient for routine examinations

Peripheral Cystoid Degeneration

  • Definition: multiple small intraretinal microcystoid cavities, most frequently seen in temporal peripheral retina
  • Characteristics: yellow tiny vesicles with blurred borders on gray background
    • Typical: occurs in all adults, may be complicated by fusion of cysts, development of cavities, and flat senile retinoschisis
    • Reticular: occurs in 18% of adults, may be complicated by bullous retinoschisis

Snowflake Degeneration

  • Definition: small yellowish dots in the peripheral retina, appear white due to light reflection
  • Findings: may span wide band in more than one retinal quadrant, most often in superotemporal quadrant
    • may be combined with other degenerations (e.g. retinoschisis, lattice, white-without pressure)
  • Prevalence: rare
  • Complications: retinal tears, retinal holes and retinal detachment

Pearl Degeneration

  • Definition: congenital retinal degeneration associated with white beads on the retina
  • Prevalence: found in up to 20% of patients
  • Characteristics: ora pearls appear like drusen, found between the retinal pigment epithelium and Bruch’s membrane or floating above RPE
  • Diagnosis: OCT findings show hyporeflective cavity with vitreous layers attached to top of lesion  

Vitreoretinal Degenerations

Lattice Degeneration

  • Definition: retinal thinning with loss of neurosensory layer, vitreoretinal adhesions at margin of lesion
  • Prevalence: found in 6-8% of patients
  • Characteristics: retinal thinning with fibrosis and vitreous liquefaction over the lesion
    • Typical: well-outlined thinning with white crossing lines
    • Atypical: found adjacent to vessels in radial pattern
  • Findings: oval or linear pattern of lesions, may be one lesion or multiple, may have yellow deposits, pigment, atrophic holes, or retinal tears
  • Complications: risk for retinal detachment and rhegmatogenous retinal detachment due to vitreous traction
    • Retinal detachment found in 14-35%
  • Treatment: most commonly prophylactic laser treatment recommended in patients with vitreous traction and retinal tears associated with flashes and floaters  

Snail track degeneration

  • Definition: groups of glistening white dots (which have been compared to frost granules or salt), may be early stage of lattice degeneration
  • Prevalence: Found in 10% of generation population, more commonly in myopic eyes (40%)
  • Characteristics: retinal thinning with vitreous liquefaction above the lesion, associated vitreoretinal tractions
  • Findings: more often in superotemporal and superonasal quadrants
  • Histologically, this lesion consists of degeneration of the neural elements of retina leading to an atrophy of the tissues with lipid deposits in the internal retinal layers
  • Complications: may lead to retinal tears in up to 54% of patients, retinal holes
  • Diagnosis: OCT findings show irregular retinal surface, vitreous destruction, vitreoretinal adhesions with traction at the margins

Retinal Tufts

  • Definition: area of retinal degeneration caused by attachment to and pulling of the vitreous  
  • Types include cystic, non-cystic and zonular traction tufts
  • Prevalence: non-cystic tufts present in up to 72% of adults, cystic present in up to 5% of adults, zonular traction tufts are present in up to 15% of adults
  • Complications: vitreous traction can lead to retinal tear and retinal detachment
  • Treatment: prophylactic laser treatment not recommended by majority of physicians, routine follow-up

Peripheral Retinal Tears

  • Definition: isolated tear due to defect in sensory retina from traction of vitreous after acute posterior vitreous detachment
  • Prevalence: 9-12% of general population
  • Characteristics: either retinal tear or retinal hole, retinal holes due to atrophic changes in neurosensory retina
  • Complications: high risk of rhegmatogenous retinal detachment, occurs in 3-18% of patients
  • Treatment: retinal tears with symptoms on presentation should be treated with prophylactic laser treatment, most commonly transpupillary retinopexy

Chorioretinal Degenerations

Paving Stone Degeneration

  • Definition: multiple rounded punched-out areas of choroidal and retinal atrophy
  • Characteristics: Lesions are yellow-white in color with due to sclera being partly visible through the atrophic choroid, discrete margins that may be pigmented, may become confluent
  • Findings: Located between ora and equator with size of one to several disc diameters
  • More common in infero-nasal and temporal quadrants
  • Large choroidal vessels seen running through the base
  • Prevalence: present in 4-28% of patients, bilateral, no sexual predilection, increasingly common with age
  • Complications: Benign lesions not associated with complications

Peripheral Retinal Drusen

  • Definition: extracellular protein and fat deposits between RPE and Bruch’s membrane, due to degeneration of RPE cells
  • Characteristics: looks like crystals
  • Findings: small, round-shaped, clearly outlined
  • Prevalence: commonly found in patients 40 years or older
  • Complications: benign degenerations
  • Treatment: prophylactic laser treatment not indicated

References

  1. Campagnoli T.R., Smiddy W.E. (2016) Peripheral Retinal Abnormalities. In: Medina C., Townsend J., Singh A. (eds) Manual of Retinal Diseases. Springer, Cham. https://doi.org/10.1007/978-3-319-20460-4_49.
  2. Engstrom RE, Glasgow BJ, Foos RY, Straatsma BR. Degenerative Diseases of the Peripheral Retina. Duane's Ophthalmology. Chapter 26. 2006 Edition.
  3. Ghazi NG, Dibernardo C. Optical coherence tomography of peripheral retinal lesions in enucleated human eye specimens with histologic correlation. Am J Ophthalmol. 2006;141(4): 740-2.
  4. Kothari A, Narendran V, Saravanan VR. In vivo sectional imaging of the retinal periphery using conventional optical coherence tomography systems. Indian J Ophthalmol. 2012 Jun; 60(3): 235-9.
  5. Lewis H. Peripheral retinal degenerations and the risk of retinal detachment.  Am J Ophthalmol. 2003 Jul;136(1):155-60.
  6. Shaimova VA. Peripheral retinal degenerations: Optical coherence tomography and retinal laser coagulation. 2nd ed. Springer International Publishing; 2017.
  7. Shaimova VA, Pozdeeva OG, Shaimov TB, et al. Optical coherence tomography in peripheral vitreoretinal degenerations diagnostics. Ophthalmology. 2013;10(4):32-9.
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