Felis ISSN 2398-2950

Retina: detachment

Contributor(s): Dennis E Brooks, David Williams

Introduction

  • Complete or partial detachment of the neurosensory retina (nsr) from the retinal pigment epithelium (rpe). Usually bilateral.
  • Cause: commonly caused by hypertension in the elderly cat. Also inflammation, trauma, neoplasia, hyperviscosity syndromes, toxicity (ethylene glycol).
  • Signs: any or all of: visual loss/compromise (often sudden onset may be difficult to appreciate if retinal detachment is unilateral), hyphema, vitreal hemorrhage, dilated pupil, leucocoria (white pupil).
  • Diagnosis: ophthalmoscopy reveals detachments and hemorrhage.
  • Treatment: depends on cause - treat primary cause and symptomatic management.
  • Prognosis: previously considered to be poor unless treatment instituted very early; degeneration of feline retina is rapid following detachment; more recently treatment of hypertensive detachments with amlodipine has resulted in recovery of sight in a significant proportion of animals.

Pathogenesis

Etiology

Pathophysiology

  • Primary (spontaneous or traumatic) - secondary to systemic or ocular disease. Partial (focal or multifocal) - total.
  • Hypertension  Hypertension vascular pathology   →   incompetence and leakage of plasma and fibrinogen.
  • Fluid accumulation results in extensive bullous detachment.
  • Inflammation: inflammatory exudates localize in the potential space between neurosensory retina and retinal pigment epithelium (junction of primordial inner and outer layers of optic cup)   →   detachments.
  • Neoplasia: tumor growth may infiltrate the sub-retinal space   →   a solid, usually circumscribed, detachment.
  • Hyperviscosity syndromes: hyperproteinemia and polycythemia vera   →   detachments by causing vascular pathology as above.
  • Hypertension affects choriocapillaris first, because lacks autoregulatory control of blood flow cf. retinal vessels   →   focal hazy opacities (reflecting leakage of plasma and fibrinogen)   →   focal intra-retinal hemorrhage if further damage to vessels occurs ('dot and blot' hemorrhages)   →   ischemic damage to the retinal pigment epithelium (rpe) (very metabolically active cells)   →   sub-retinal exudation and detachment.
  • Detachment first flat, then multiple bullae (cobblestone appearance), then total.
  • Uncontrolled hypertension   →   intra-vitreal hemorrhage from retinal vessels, possible hyphema as bleeding occurs from iris vessels. Intra-ocular hemorrhage may   →   secondary glaucoma Glaucoma.
  • Hyperviscosity syndromes   →   sludging of blood in vessels   →   hypoxic damage   →   pathophysiology as for hypertension.

Timecourse

  • Usually 'sudden' in onset, ie sudden objective signs but this relates to the second eye affected - the first may have a chronically detached (and thus permanently damaged) retina.
  • Early signs may be picked up on examination before objective signs, eg at routine annual vaccination (a good reason for ophthalmic examination at every routine examination in the older cat).

Diagnosis

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Littman M P (1994) Spontaneous systemic hypertension in 24 cats. JVIM (2), 79-86 PubMed.
  • Sansom J, Barnett K C, Dunn K A et al (1994) Ocular disease associated with hypertension in 16 cats. JSAP 35 (12), 604-611 VetMedResource.

Other sources of information

  • Petersen-Jones S & Crispin S (2002) BSAVA Manual of Small Animal Ophthalmology. 2nd edn. British Small Animal Veterinary Association. ISBN 0 905214 54 4


ADDED