cataract-OPTH

Slide 1: 

BY MAHALINGAM.P BVM06066

CATARACT : 

CATARACT Opacity of the lens Causes visual impairment/blindness Only effective treatment is surgery. Aim - extraction of diseased lens and replacement by an artificial intraocular lens Success rate depends on microsurgical techniques - phacoemulsification

INCIDENCE : 

INCIDENCE Immature cataracts - younger dogs, Hypermature cataracts - older dogs Inherited cataract – 2 -8 years of age Prevalency - increased with age Above 13.5 years of age - some degree of lens opacity. More in Spitz followed by Mongrels and German Shepherd

Etiology : 

Etiology Hereditary – Bilateral Infections or toxins Trauma Senile - ≥ 6 years of age Diabetes Harmful oxidizing effects in the body Dietary deficiency

How does cataract form : 

How does cataract form Normal lens is maintained in a dehydrated state (66% water and 33% protein ) complicated sodium water pump-keeps water/protein in balance state. Changes in the biomechanical system in the lens - water moves into the lens percentage of insoluble protein increases. loss of transparency and cataract formation.

Diabetes : 

Diabetes Develop very rapidly Increases glucose concentrations in the lens extra glucose is converted into sorbitol Increase influx of water into the lens Breakdown of the lens fibers resulting cataract

Stages or types of cataract : 

Stages or types of cataract Incipient cataract – initial, rarely interferes with vision, slight opacity, partial vision. Immature cataract - more severe, blurred vision, portion of the eye is cloudy, vision is not completely lost Mature cataract -entire area is cloudy - Hypermature- small refractive crystals

Signs of cataract : 

Signs of cataract Incipient and Immature cataract – fundic reflex - +ve Mature and hypermature cataract – fundic reflex - -ve Hypermature – increased anterior chamber depth, lens-induced uveitis, small refractive crystals and subscapular plaques

Cont., : 

Cont., Immature cataract Mature cataract

Diagnosis : 

Diagnosis Ophthalmic examination 1. Day light examination. Menace reflex. Obstacle course test. Cotton ball test. Direct and indirect Ophthalmoscopic examination Tonometry

Menace Response : 

Menace Response

Pupillary Light Response : 

+Ve PLR -Ve PLR Pupillary Light Response

Indirect Ophthalmoscopy : 

Indirect Ophthalmoscopy

Schiotz’s tonometery : 

Schiotz’s tonometery

Differential diagnosis : 

Differential diagnosis Nuclear sclerosis - a normal change in the lenses of older dogs (> 6 years of age) Slight graying of the lens – Both the eyes compression of the linear fibers in to lens

Corneal opacity : 

Corneal opacity Corneal opacity Cataract

Phacoemulsification principles : 

Phacoemulsification principles Have two integrated components. 1-ultrasound system for breaking up the lens (USP is 28.5 KHz) Electrical energy - generate ultrasonic waves - piezoelectric crystals - mechanical energy Emulsify the nucleus of lens 2- fluidic system for irrigation, aspiration and cooling

Phacoemulsification unit : 

Phacoemulsification unit

Advantages of phacoemulsification : 

Advantages of phacoemulsification Microsurgery shorter surgical time smaller corneal incision, less manipulation less intraoperative trauma to ocular tissues more efficient removal of lens cortical material Excellent postoperative outcome.

Limitations of phacoemulsification : 

Limitations of phacoemulsification Most difficult intra-ocular techniques Experience needed Longer time to master Risk of posterior capsule perforation

Slide 21: 

THANK YOU