Cataract

CataractCataract

Opacity of lens is known as cataractOpacity of lens is known as cataract

Cataracts are the most common cause Cataracts are the most common cause of treatable blindness in dogs of treatable blindness in dogs

severe cataracts severe cataracts cause blindnesscause blindness

By disrupting the By disrupting the ability of the ability of the lens to focus lens to focus light rays onto light rays onto the retina the retina

toy poodle, toy poodle, miniature and miniature and standard poodle, standard poodle, English cockerEnglish cocker

Spaniel, Boston Spaniel, Boston terrier, golden terrier, golden retriever, retriever, rottweiler, rottweiler, Labrador Labrador retriever,retriever,

Miniature Miniature schnauzer, schnauzer, bichon frise, and bichon frise, and chow chow chow chow

prevalence of cataracts increases with ageprevalence of cataracts increases with age

in dogsin dogs Diabetes mellitus is the second most Diabetes mellitus is the second most

common cause ofcommon cause of

cataracts in the dog cataracts in the dog less common causes include other metabolicless common causes include other metabolic

diseases, toxins, drugs, congenital diseases, toxins, drugs, congenital abnormalities, dietary deficiencies,abnormalities, dietary deficiencies,

trauma, radiation therapy, and aging trauma, radiation therapy, and aging

Tapetum Tapetum

Eyeshine occurs in a wide variety of colors including blue, green, yellow, pink and red.

Incipient cataracts Incipient cataracts involves <10% to involves <10% to 15% of the lens15% of the lens

Immature cataracts vary widely in Immature cataracts vary widely in appearance and may affect only a appearance and may affect only a small portion of the lens to almost small portion of the lens to almost the entire lensthe entire lens

By definition,By definition, a tapetal reflection is apparent with a tapetal reflection is apparent with

immature cataracts, althoughimmature cataracts, although vision may be diminished if the vision may be diminished if the

cataract is well developed. cataract is well developed.

A mature cataract affects the entire lensA mature cataract appears as a solidwhite opacity of the lens, and affected dogs are severely impaired visually

Hypermature Hypermature cataracts have cataracts have undergone undergone liquefaction andliquefaction and

resorptionresorption

Hypermature cataracts Hypermature cataracts often have a often have a crystalline crystalline appearancewith appearancewith wrinkling of the lens wrinkling of the lens capsule capsule

A tapetal reflection may or may not be present.

Vision with hypermature cataracts is variable depending upon the degree of liquefaction.

Congenital/ aquired Congenital/ aquired Complete/ partialComplete/ partial Stationary / progressiveStationary / progressive Senile/toxicSenile/toxic Juvenile cataract – prognosis is goodJuvenile cataract – prognosis is good

Capsular/ Capsular/ cortical/ cortical/ lamellar(bet. lamellar(bet. Lens nucleus Lens nucleus and and cortex)/nuclear/dcortex)/nuclear/diffuse(entire lens iffuse(entire lens substance)substance)

The most common treatment The most common treatment for cataracts is surgical for cataracts is surgical removal by removal by phacoemulsification.(Phaco- phacoemulsification.(Phaco- lens and emulsification- lens and emulsification- liquifying/ breaking)liquifying/ breaking)

Tests indicatedTests indicated prior to surgery include a prior to surgery include a

complete ophthalmic complete ophthalmic examination,examination,

complete blood count, complete blood count, biochemical panel, urinalysis, biochemical panel, urinalysis, electroretinography (ERG), and electroretinography (ERG), and ocular ultrasonography.ocular ultrasonography.

Treatment Treatment Discission/ Discission/ needling : ant . needling : ant . Capsule is incised Capsule is incised in cruciate in cruciate fashion, using a fashion, using a cataract needle – cataract needle – aqu.humour in aqu.humour in contact with lens contact with lens substance- substance- facilitate facilitate resorption – resorption – repeated many repeated many timestimes

Removal of Removal of lens : lens : intracapsular intracapsular (with capsule)- (with capsule)- difficult in difficult in animals – sus.lig animals – sus.lig is tough is tough

Extra capsular Extra capsular (without (without capsule)- capsule)- successfulsuccessful

ProcedureProcedure

Extracapsular: fix the eye ballExtracapsular: fix the eye ball Canthotomy may be done to increase the Canthotomy may be done to increase the

exposureexposure Incise the cornea at limbus- graefe’s knife/ Incise the cornea at limbus- graefe’s knife/

scissorsscissors Incise the anterior capsule of lens Incise the anterior capsule of lens Catract scoop is used to remove the lens Catract scoop is used to remove the lens

substancesubstance Suture the corneal woundSuture the corneal wound In man dissolution of the opaque lens by using In man dissolution of the opaque lens by using

0.02% trypsine has been reported.0.02% trypsine has been reported.