Lens and Vitreous

T/F nuclear sclerosis is a normal part of aging?

True

What is the effect of nuclear sclerosis on vision?

Minimal

What does nuclear sclerosis look like?

Grayish blue haze

What do you need to differentiate nuclear sclerosis from?

Cataracts

What can you do to differentiate nuclear sclerosis from a cataract?

Aim the light dorsally and use tapetal reflection

What is a cataract?

Opacity in the lens or capsule

What should the neuro things be with cataracts

Normal PLR and a dazzle reflex

Absent menace response

What are the 2 most common causes of cataracts in dogs?

Hereditary

Metabolic from Diabetes mellitus

What is the most common cause of cataracts in cats and horses?

Secondary to uveitis

What is a congenital cataract?

At birth

What is a juvenile catarac?

Young animal 1-5yrs

How do you classify cataracts?

Etiology

Age of onset

Location in lens

Stage of development

What are the cataract stages?

Incipient

Immature

Mature

Hypermature

What is an punctate opacity with <15% of the lens for a cateract?

Incipient

What is a cataract that is between 15% and 99% of the lens with some tapetal reflection?

Immature

What is a cataract with 100% opacification with no tapetal reflection and no menace response?

Mature

What is a resorption of some cataractous lens fibers causing a sparkling, wrinkled capsule with some tapetal reflection and some vision?

Hypermature

What stage of cataract do you lose menace response?

Mature

Incipient cataract

Immature cataract

Mature cataract

Hypermature cataract

Describe the steps of lens metabolism

1. High blood glucose causes elevated aqueous humor glucose, increasing lens glucose and overwhelming hexokinase enzyme

2. Excess glucose is metabolized by aldose reductase and converted to sorbitol

3. Sorbitol accumulates within the lens causing an osmotic effect

4. Fluid is drawn into the lens causing cataract

How is glucose normally metabolized in the lens?

Anaerobic glycolysis

What are two other concerns of cataracts that are not blindness?

Phacolytic uveitis

Phacoclasitc uveitis

What is phacolytic uveitis?

Leakage of lens proteins through intact lens capsule

What is phacoclastic uveitis?

Rupture of lens capsule exposing lens proteins acutely

How can you prevent lens-induced uveitis during cataract therapy?

Topical NSAIDs

How do you treat active lens induced uveitis?

Topical steroid

Oral NSAID

When is the best time to do cataract surgery?

Mid-immature with no lens induced uveitis

What are some considerations for cataract surgery?

Uveitis must be controlled

General health needs to be good

Temperament of animal

Client commitment

What is the only way to cure cataractive?

Elective cataract surgery

What is LIU?

Lens induced uveitis

What is included in the work up for cataract surgery?

Complete ophthalmic exam

Physical exam to ensure it is safe

Gonioscopy

Electroretinogram

Ocular ultrasound

What is the rate of cataract surgery complications?

10-15%

What are the postoperative complications of cataract surgery?

Uveitis

Glaucoma

Retinal detachment

Endophthalmitis

What causes lens luxation?

The breakdown of zonules that holds the lens in place

What is subluxation of the lens?

Partial detachment of lens zonules

What is a lens luxation?

Complete detachment of lens zonules

What is an anterior lens luxation?

Lens is anterior to the iris

What is a posterior lens luxation?

Lens is posterior to iris, usually in vitreous chamber

What breeds are susceptible to primary lens luxation?

Terriers

What causes secondary lens luxation?

Chronic glaucoma

Uveitis

Trauma

Intraocular tumors

Hypermature cataracts

When is anterior lens luxation an emergency?

If it is recent and the dog is visual

How do you treat an emergency lens luxation?

Intracapsular lens extraction

How do you treat the secondary lens luxation with anterior lens luxation?

Mannitol IV or glycerin PO

Topical/oral carbonic anhydrase

Why should you not give miotics like pilocarpine or latanoprost to a patient with an anterior lens luxation?

It traps the lens in the anterior chamber

T/F secondary lens luxation is an emergency?

True

What do you treat primary lens subluxation?

Proactive surgical lens removal

Medical therapy BID to keep pupil miotic and lens back with latonorpost

How do you manage posterior lens luxation?

Miotic therapy

How large is the vitreous?

>2/3 of globe volume

What is vitreous humor made of?

99% water 1% collagen

What does the vitreous do?

Support lens anteriorly and support retina posteriorly

Maintains globe shape

Transmits to retina

What are some vitreous abnormalities?

Vitreal degeneration

Vitreal cells

Vitreal hemorrhage

Asteroid hyalosis

What is ateroid hyalosis?

Small white particles in the vitreous that are Ca2+ or phospholipids that move with the eye

What is the significance of asteroid hyalosis?

Incidental