Ophthalmology: Uvea Glaucoma Lens Flashcards
- What makes up the anterior uvea?
- What is the posterior uvea?
- Iris and ciliary body
- Choroid
Uvea is the most vascular, most pigmented and most immunologically reactvie tissue in the eye
- What is the purpose of the iris?
- What is ‘wall-eye’?
- What controls the dilator/constrictor muscle of the iris?
- What is the purpose of the ciliary body?
- What inervated the ciliary muscle?
- Variable diaphragm controlling the amount of light entering the eye
- Lack of pigment of the posterior epithelium of iris (white)
- Dilator- sympathetic, constrict- parasympathetic
- Accomodation of the lens via the action of ciliary muscle
- Parasympathetic fibres of nerve III
Zonule attaches to ciliary body and produced aqueous
What is a persistent pupillary membrane remnant?
- Mesodermal membrane remnants that cover pupil in vitro
- No treatment necessary
- What is anterior uveitis?
- What are the clinical signs?
- Inflammation of the iris and ciliary body
- Clinical signs
* Pain- blephrospasm
* Aqueous flare- aqueous not clear (proteins)
* Miosis
* Hypotonia- eye soft (reduced aqueous)
* Hypoyon- inflam cells and exudate in anterior chamber
* Keratic precipitates- focal accumulations of inflammatory cells on the deep corneal surface in sub-central area
* Iris- swollen and dull
* Corneal oedema
* Loss of sision- variable
Without treatment of anterior uveitis what secondary and permanent changed can occur?
- Synechiae- adhesion of inflammed iris to anterior lens or cornea to drainage angle
- Iris rests- patches of pigment on anterior lens
- Iris- may darken
- Glaucoma- occlusion of drainage angle or circumferential posterior synechiae occluding the pupil
- Cataract
What are causes of anterior uveitis?
How is it treated?
- Corneal injury and ulceration
- Blunt and penetrating trauma
- Release of antigenic lens protein
- Intra-ocular infection
- Septicaemia
- Intra-ocular neoplasia
- Pyometra
- Some idiopathic/immune mediated
Other than eliminating primary problem symptomatic
* Mydratics- atropine
* Anti-inflammaties- topical steroids- dexameth/pred acetate
What are the differentials for anterior uvea masses?
Order of frequency
* Uveal cysts
* Naevi
* Melanoma
* Ciliary body adenoma
* Metastasis
How can the following be differentiated?
1. Uveal cysts
2. Anterior uveal melanoma
3. Limbal melanoma
4. Ciliary body adenomas
5. Metastatic tumours
- May arise from posterior iris or ciliary body, break free to anterior chamber, pigmented but spherical, not solid, transilluminate
- Most common intra-ocular neoplasm- solid mass in iris or ciliary body, usually heavily pigmented- enucleation curative
- Heavily pigmented arising within the wall of the eye at the limbus
- Second most common- pink masses protruding into the pupil
- Lymphoma most common- check for mammary tumours
What is glaucoma?
- Abnormal rise in intra-ocular pressure
- Problem of drainage
Describe the normal process of aqueous (not glaucoma)
- Produced in ciliary body
- Passes through pupil into anterior chamber
- Drains at irido-corneal angle
What are clinical signs of acute glaucoma?
- Red eye
- Severe pain and general lethargy
- Mild corneal odema- steamy
- Unresponsive mid-dilated pupil
- Blindness
- Palpably hard globe
- Normal globe size
What are the clinical signs of chronic glaucoma?
- Enlarged eye
- Blindness
- No response to light
- Tears in descemets membrane
- Variable corneal opacity, vascularisation, pigmentation
- Lens sub (luxation)
- Visible retinal degeneration and optic disc cupping
- Variable degree of pain
What breeds are predisposed to primary cause of glaucoma?
- English and welsh springer
- Cockers
- Bassett
- Dandie dinmont
- Flat-coated retriever
- Great dane
- Golden retriver
- Minature poodle
- Welsh terrier
What causes primary glaucoma?
Dysplastic drainage angles with sudden decompensation
Primary should be referred
What are secondary causes of glaucoma?
- Lens luxation
- Anterior uveitis
- Hyphaema
- Intumescent and hypermature cataracts
- Tumours
- Retinal detachement
- Trauma and perforated ulcers
- Chronic retinal detachment
- Intraocular haemorrhage
What are the two main topical treatments for glaucoma?
- Carbonic anhydrase inhibitors
- Prostoglandin analogues
Or both
Prophylaxis in the good eye
How can glaucoma be surgically treated?
Numerous procesures
* Laser
* Shunts
None amazing- specialist
Describe the anatomy of the lens?
- Transparent avascular structure
- Lens fibres enclosed in elastic capsule
- Supported by ciliary body via zonular fibres
- Lens protein is antigenic- incited inflammatory response if capsule ruptured
What are the different causes of lens luxation?
- Primary
- Secondary to chronic glaucoma
- Trauma
- Hypermature inflexible cataracts
What are the stages of primary lens luxation?
- Anterior lens luxation
- Posterior luxation/subluxation
What are the clinical signs of anterior lens luxation?
- Sudden onset poor vision
- Glaucoma
- Some anterior uveitis
- Glaucoma from obstruction of pupil
What are the clinical signs of posterior luxation/subluxation?
- Doesn’t cause glaucoma
- Iridodonesis (trembling of iris)
Susceptible breeds- bilateral buyt not simultaneous
How is lens luxation managed?
- Can be removed surgically- not done
- Can relocate- specialist
- Subluxation- prostoglandin analogues to prevent anterior luxation
Prognosis guarded
What is a cataract?
- Any opacity of the lens
- Disruption of fibre arrangment
- Due to acumulation of osmotically active substances
- Does not impair PLR
What are the different classifications of cataracts?
- Hereditary
- Congenital
- Diabeteic
- Secondary to uveitis
- Truama
- Spontaneous/idopathic
What are the different stages of development of cataracts?
- Incipient- small opacities
- Immature- more extensive, good tapetal reflex
- Intumescent- rapidly developing, can obstruct drainage- diabetes
- Mature- total opacity no fundic reflex
- Hypermature- lens with irregular wrinkles surface
How is nuclear scelerosis distinguished from cataract?
- Affects the nucleus only
- Does not noticibly affect vision
- No opacity on distant direct ophthalmoscopy
Requires no treatment
- How do diabetic cataracts often progress
- What can it lead to?
- How can they be treated?
- Sudden onset blindness- total cataracts in few days
- Lens takes in water- leakes causes lens-induced uveitis
- Surgery- extraction
How can cataracts be managed?
- Medical is of no avail
- Specialist- phacoemulsification
- Surgery- specialist
Desirable conditions for surgery
* Significantly impaired vision
* Easily handled
* Good PLR
* No history of impaired vision
What is vitreous?
- Soft gel, some collagen anf hyaluronic acid
- Fills posterior part of eye
What different conditions can affect the vitreous?
- Persistent hyaloid remnants- no significance
- PHPV
- Asteroid hyalosis- older dogs (white specs)
- Other vitreous opacities- incidental finding
PHPV- persistent hyperplastic primary vitreous
