Peripheral Retinal Degenerations

 Peripheral Retinal Degenerations

Definition

Peripheral retinal degenerations refer to degenerative changes that lie parallel to the ora serrata in the peripheral portions of the retina. These include two basic types:

❖ Harmless retinal changes such as pars plana cysts of the posterior ciliarybody or peripheral chorioretinal atrophy (cobblestone degeneration).

❖ Precursors of retinal detachment such as local thinning of the retinareferred to as snail track or lattice degeneration.

Epidemiology: 

The prevalence of the lesions is 6 – 10%.

Pathogenesis: 

Unknown.

Symptoms: 

Peripheral retinal degenerations are asymptomatic.

Diagnostic considerations: 

The diagnosis is made by ophthalmoscopicexamination of the peripheral retina with the pupil dilated. The retina may be examined by indirect binocular ophthalmoscopy or using a three-mirror lens.

Cobblestone degenerations appear as whitish sharply defined localizedareas of extensive atrophy of the retina, pigment epithelium, and choriocapil-laris that lie between the ora serrata and the equator. Snail track degenera-tion presents with yellowish, whitish radiant dots consisting of microglia andastrocytes. Lattice degeneration presents with thinned retinal areas with whitish sclerotic vessels. This results in reactive focal atrophy and hypertro-

phy of the retinal pigment epithelium in the region of equatorial degenera-tion and liquefaction of the overlying vitreous body.

Differential diagnosis: 

The findings are highly characteristic and easily diag-nosed clinically. Rarely, vascular processes or inflammatory changes and scars from other causes must be considered in a differential diagnosis.

Treatment: 

Treatment is either not required or not recommended as lasertherapy does not reduce the risk of retinal detachment. Ophthalmoscopic fol-low-up examinations should be performed at regular intervals.

Prophylaxis: 

No prophylaxis is possible.

Clinical course and prognosis: 

The clinical course is usually benign. Roundatrophic retinal breaks can develop in the areas of snail track and lattice degeneration. However, the long-term risk of retinal detachment is only 1%.

Comments

Post a Comment

Popular posts from this blog

Developmental Anomalies of the Eye Lens

Image
  Developmental Anomalies of the Lens Anomalies of lens shape are very rare.  Lenticonus  is a circumscribed conical protrusion of the anterior pole (anterior lenticonus) or posterior pole (poste-rior lenticonus). A hemispherical protrusion is referred to as  lentiglobus . Symptoms include myopia and reduced visual acuity. Some patients with Alport’s syndrome (kidney disease accompanied by sensorineural hearing loss and anomalies of lens shape) have  anterior  lenticonus.  Posterior lenti-conus  may be associated with a lens opacity (Fig. 7. 6 ). Treatment is the sameas for congenital or juvenile cataract. Microphakia  refers to a lens of abnormally small diameter. Any interrup-tion of the development of the eye generally leads to microphakia. This can occur for example in Weill-Marchesani syndrome (see Table 7. 5 ).
Read more

Optic Nerve

Image
  Optic Nerve Basic Knowledge The optic nerve extends from the posterior pole of the eye to the  optic chiasm  (Fig. 13. 1 ). After this characteristic crossing, the fibers of the optic nerve travel as the  optic tract  to the  lateral geniculate body.  Depending on the shape of the skull, the optic nerve has a total length of 35 – 55 mm. The nerve consists of: An intraocular portion.  An intraorbital portion.  An intracranial portion.   Intraocular Portion of the Optic Nerve The intraocular portion of the optic nerve is visible on ophthalmoscopy as the  optic disk . All the retinal nerve fibers merge into the optic nerve here, and thecentral retinal vessels enter and leave the eye here. The complete absence of photoreceptors at this site creates a gap in the visual field known as the  blindspot . Shape and size:  The optic disk (Fig. 13. 2 ) is normally slightly vertically oval with an average area of approximately 2.7 mm...
Read more

Curative Corneal Procedures

Image
  Curative Corneal Procedures Penetrating Keratoplasty  (Fig. 5. 18a ) Principle:  This involves replacement of diseased corneal tissue with a full-thickness donor graft of corneal tissue of varying diameter. A clear, regularly refracting button of donor cornea is placed in an opacified or irregularly refracting cornea. The corneal button is sutured with a continuous single or double suture (Fig. 5. 19 ) or with interrupted sutures. (For special considera-tions in corneal transplants, see also Morphology and healing.) Penetrating keratoplasty can be performed as an  elective procedure  to improve visual acuity or as an emergency procedure ( emergency kerato-plasty ). Emergency keratoplasty is indicated to treat a perforated or nonheal-ing corneal ulcer to remove the perforation site and save the eye ( tectonic ker-atoplasty ). Indications:  Corneal diseases that affect the full thickness of the cornealstroma (corneal scars, dystrophy, or degeneration) or pr...
Read more