Uvea Flashcards
Conditions of the Uvea:
- Uveitis
- Anterior Uveitis
- Posterior Uveitis
Tumors
- Naevus
- Melanoma
Naevus
Prevelance
Presentation
Prevalence: 10%.
Presentation: The following characteristics of a nævus help to distinguish it from a melanoma:
1. Size
2. Growth
3. Elevation.
Symptoms:
1. Asymptomatic.
2. Small: Choroidal nævi are usually smaller than 3 disc diameters.
3. Does not grow after puberty and does not distort surrounding structures.
4. Flat.
Melanoma
Presentation
Treatment
Presentation
- gradually enlarges and may become large, becomes elevated, distorts surrounding tissues and may cause a loss of vision.
- It is the most common primary intraocular tumour in adults.
- The average age of onset is 50 years
- rarely occurs in Black races.
- It may present asymptomatically during a routine examination or with a decrease in vision or a field
defect.
Treatment: modalities include laser therapy, irradiation, local resection and enucleation.
Anatomy: Parts of the Uvea
The uvea is the pigmented vascular layer of the eye. It consists of 3 parts: 1. Iris: Anterior uvea 2. Ciliary body: Anterior uvea 3. Choroid: Posterior uvea
UVEITIS
Definition Classification Cause Pathology Presentation Treatment Complications
DEFINITION
Uveitis = intraocular inflammation.
CLASSIFICATION ANATOMICAL Anterior uveitis: Iridocyclitis--> Iritis Cyclitis Posterior uveitis: Choroiditis Anterior and Posterior uveitis: Panuveitis TEMPORAL 1. Acut 2. Chronic 3. Recurrent
CAUSES:
NONINFECTIVE CAUSES
1. Sarcoidosis: anterior and posterior uveitis are common.
2. Ankylosing spondylitis: anterior uveitis is common.
3. Juvenile chronic arthritis: anterior uveitis is common.
4. Reiter’s syndrome: conjunctivitis, anterior uveitis. Large joint arthritis and urethritis or cervicitis complete the triad.
5. Behçet’s syndrome: triad–> anterior uveitis, hypopion formation, aphthous mouth ulcers and genital ulcers.
6. Trauma: the commonest cause of anterior uveitis in children.
7. Sympathetic ophthalmia: bilateral, chronic panuveitis that occurs after a substantial penetrating injury to one eye.
- Onset: 10 days- 50 years after the exciting trauma
- Does not occur if the injured eye is removed within 10 days of the original injury.
- AI disease
- Treatment: injured blind eye should be removed within 10 days of the injury to prevent future progressive immune damage to the remaining only seeing eye.
8. Infection elsewhere in the body may cause a uveitis on a hypersensitivity basis e.g. tooth abscess,
sinusitis.
9. Many others.
INFECTIVE CAUSES
1. Toxoplasmosis: Toxoplasma gondii, an intestinal parasite of the cat, is the most common suspected single cause of a posterior uveitis.
2. TB: anterior and posterior segment inflammation may occur both on a hypersensitivity or infective basis.
3. Syphilis: intrauterine infection –> posterior uveitis –> “salt and pepper” fundus, normal vision.
Anterior and posterior uveitis may occur in the secondary stage of the acquired disease.
4. Herpes simplex
5. Herpes zoster
6. cytomegalovirus
7. meningococcus
8. candida.
PATHOLOGY inflammation 1. vascular dilation 2. extravascular fluid leakage 3. leucocyte infiltration. This includes all tissues internal to the sclera. The optic disc is not included.
CLINICAL CHARACTERISTICS ANTERIOR UVEITIS Symptoms: 1. Painful red eye, no pain in child 2.Dull vision 3. Photophobia 4.Tearing Signs: 1. < VA 2. Ciliary (circumcorneal) injection. 3. Anterior chamber flare (light reflected from aqueous protein)/ in severe uveitis anterior chamber haze--> iris appear dull and lighter in colour. 4. Keratic precipitates (KP): deposits on inferior corneal endothelium in a triangular pattern, base down--> white, yellow or brown spots, and consist of precipitated white cells, fibrin, pigment and débris from the aqueous humour. 5. Hypopyon if severe: white cells and fibrin precipitate in the inferior anterior chamber angle. 6. Miosis. 7. Positive tests for iritis. 8. Discomfort not relieved by local anaesthetic. 9. Dull view of the fundus. POSTERIOR UVEITIS Symptoms 1. Comfortable white eye 2. < cision - Lesions in/adjacent to macula: rapid onset of severe visual loss - peripheral lesions: asymptomatic. Signs: 1. < VA 2. Dull view of the fundus due to vitreous haze: flare and cells. 3. Inflammatory foci. - Choroidal/retinal inflammatory focus: cotton wool like appearance--> white/ yellowish white with poorly circumscribed borders due to exudation and cellular infiltration. - Retinal vasculitis/perivasculitis--> poorly defined white sheath around the involved blood vessel segment. The sheath represents inflammatory cells in and around the vessel wall.
COMPLICA TIONS
ANTERIOR UVEITIS
1. Posterior synechiae: Adhesions of posterior surface of iris to anterior lens capsule tend –> irregular and fixed pupil–> obstruct the flow of aqueous through the pupil sufficiently–> anterior bulging of iris–> secondary acute angle closure.
2. Effects on the trabeculum retard drainage of aqueous to cause > IOP and eventually chronic open angle glaucoma. (a) Blockage of the trabeculum by cells and débris.
(b) Trabeculitis leading to trabecular sclerosis.
3. Cataract if chronic.
POSTERIOR UVEITIS
1. Choroidoretinal scar formation: If macula involved
–> loss of visual acuity.
2. Exudative retinal detachment: Exudation of fluid between RPE and neuroretina–> Resolution when inflammatory process controlled and the fluid is reabsorbed.
3. Rhegmatogenous retinal detachment: due to retinal hole formation as a result of inflammation or vitreous traction–> sx repair required, but the prognosis is poor.
4. Papillitis–> optic atrophy.
MANAGEMENT
- Referral: ophthalmologist.
- A topical mydriatic/cycloplegic is used in anterior uveitis for the following reasons:
(a) Dilation and movement of the pupil < probability of posterior synechiae–> iris and anterior lens capsule usually least in contact in the fully dilated position.
(b) Pain caused by ciliary muscle and iris sphincter spasm, and relaxation of these leads to pain relief. - Steroidal topically, subconjunctivally or systemically. and/or NSAIDS are < inflammation.
- Management of complications.
