Cataracts, Dr. Christa Corbett, 11/8/14

Christa Corbett, DVM, MS, DACVO

November 8, 2014

Outline Anatomy of the lens

Nuclear sclerosis vs. cataract

Stages of cataracts

Etiologies of cataracts

When to refer

Pre-operative care

Cataract surgery

Post-operative care

Medical treatment ???

Anatomy

AP

Zonules

Lens capsule

Nuclear vs. Cortical

Lens epithelium

Anterior

Produces new fibers

Equator

Active mitosis

Nuclear (Lenticular) Sclerosis

Lens continually produces

new cortical fibers

Compression of nucleus in

patients over 6-8 years old

Causes light to scatter

We can still see retina, patient

is still visual

Diagnosis:

DILATION and RETROILLUMINATION

AP

RETROILLUMINATION

Stages of Cataract

Incipient - <10%

Minor opacities, often incidental

Perfect view of fundus

Stages of Cataract

Early immature – 10-50%

Obvious opacity, but good tapetal

reflex and good view of fundus

Stages of Cataract

Late immature – 51-99%

Can still see tapetal reflex, but very

limited view of fundus

Stages of Cataract

Mature – 100%

No tapetal reflex on retroillumination

Stages of Cataract

Hypermature – resorbing

Varying degrees of lens opacity

Wrinkled capsule, “Sparkly” cataract

And other minutia terms that

Ophthalmologists love . . .

Morgagnian – subset of hypermature

Cortex resorbs, nucleus drops

And other minutia terms that

Ophthalmologists love . . .

Brunescence – Yellow!

Very old patients, very old cataracts

And other minutia terms that

Ophthalmologists love . . .

Intumescence = FAT

Quick forming diabetic (occasionally

inherited)

Tendency to progress

Nuclear: rarely progress

Cortical: variable, often progress

(esp. anterior)

Equatorial: often progress

AP

Etiology

Inherited

Diabetes

Senile

Trauma

Uveitis

Horses

Cats

Nutrition

Irradiation

Hypo/Hyper Ca2+

Electrocution

Toxic

PRA

Drugs

Diabetes mellitus

Dogs only!

75% incidence within one year of onset of DM

Mechanism of action Increased amount of glucose in the eye

Overloads the hexokinase pathway, so excess glucose shunted into sorbitol pathway

○ Enzyme Aldose Reductase is responsible for this shunting

Sorbitol is too big to diffuse through the lens capsule

Osmotic gradient = more fluid pulled into lens

○ Vacuolization of proteins

○ Lens protein aggregation

Senile Cataracts

Refers to time of onset, and etiology

Very slow to progress

I do not have an age cut off, but I will

NOT do surgery in an elderly dog if

there are signs of:

Cognitive dysfunction

Retinal degeneration

Significant corneal degeneration

When to refer

Do NOT let the cataract “ripen!”

The earlier the better

It may be possible to get a view of the retina

in early cases

Start anti-inflammatory therapy before

problems arise

Clients can prepare themselves

and save money, take vacation

time, etc.

Sequelae of cataracts if surgery

not performed early . . .

Loss of vision

Lens induced uveitis: Cataractous lens proteins

leak out of lens uveitis

Lens capsule rupture

Lens luxation

Secondary glaucoma

Retinal detachment

Capsular mineralization

Treatment before referral

Anti-inflammatory therapy If cataract is immature or beyond

Topical steroid○ Prednisolone Acetate ($$$)

○ NeoPolyDex

Topical NSAID○ Diclofenac

○ Flurbiprofen

Quiet eye: SID-BID

Hyperemic, miotic, aqueous flare: TID-QID○ Consider an oral NSAID as well

Check bloodwork for diabetes

Monitor for glaucoma if possible

Retinal Testing

Outpatient testing, typically half-day

hospital stay

Sedation is rarely necessary

Retinal FUNCTION

Electroretinogram

Retinal STRUCTURE

Ocular ultrasound

Retinal Testing

Artificial lenses

Placed in every eye if possible

Cannot be placed with:

Zonular instability

○ Risk of future lens luxation

Ruptured lens capsule

○ Iatrogenic or pre-op (especially diabetics)

Hypermature cataract with immense

capsular contraction = too small to hold a

lens

Artificial lenses

Rigid

Polymethylmethacrylate (PMMA)

Requires an 8mm corneal incision

○ More risk of astygmatism or incisional leakage

Foldable

Acrylic

Silicone

Folds into injection cartridge,

3mm incision

Suturing

9-0 monofilament absorbable suture

(PGA, Vicryl®)

Smaller than a piece of my hair!

Suture pattern is surgeon-dependent

Double continuous, or “Shoe-lace”

9-0 vicryl

6-0 silk

Hair

E-collar is

MANDATORY!

Post-Operative Patient

Patients are immediately visual!

Success rates with surgery

85-95% success for most patients

Success rate decreases with:

○ Hypermaturity

○ Uncontrolled lens induced uveitis

○ High or High-normal IOPs

Might be even lower % in certain breeds

○ Bichon (Retinal detachment)

○ Boston Terriers and Pugs (Glaucoma, corneal health)

○ Shih Tzu (Corneal health)

Post-op Ocular Complications

Common:

Fibrin

Refractory uveitis

Secondary glaucoma

Retinal detachment

Corneal ulceration

Posterior capsular opacity

Rare:

Artificial lens or capsular luxation

Hyphema

Endophthalmitis (sterile or bacterial)

Posterior Capsular Opacification

100% of dogs

Minimal PCO in most cases!

Hypermature cataract leading to

mineralized capsule plaques

Post-operative care

Enough eye drops to drive our clients crazy!

4-6 different medications, all QID

○ Anti-inflammatory drops

Pred acetate and Diclofenac

○ Antibiotics

Something that will penetrate the cornea = Fluoroquinolone

○ Lubricant gel

Optixcare gel

○ +/- Glaucoma drops

○ +/- Dry eye meds (only if previously diagnosed)

Post-operative care

Oral medications BID

Antibiotic (Clavamox or Cephalexin)

Anti-inflammatory (Rimadyl)

E-collar!!!

24-7 for at least 2 weeks!

Warm compress the eyes to keep clean

of discharge

Post-operative care

Rechecks:

+/- 24 hours

+/- 1 week

2 weeks – taper drops, remove e-collar

6 weeks

3 months

Every 4-6 months for LIFE!

○ Every complication listed can happen even

years afterwards!

Rechecks – Primary care vet

vs. DACVO? Every single recheck:

Schirmer tear test

Intraocular pressure

Slit lamp anterior exam○ Corneal health

○ Grade of aqueous flare

○ Grade of Posterior cortical opacity (PCO)

○ Lens position (subluxation, centration of IOL)

Indirect fundic exam○ Retinal position – must look all the way out to the

ora ciliaris retinae, most common area for detachments to begin

○ Signs of retinal hemorrhage

○ Signs of subretinal edema

○ Signs of vitreal degeneration

Non-surgical patients

Topical NSAIDs for life (SID-BID)

Monitor IOP every 3-4 months

Painful:

Glaucoma, uveitis and lens luxation

Non-painful:

Retinal detachment and hyphema

Will medical treatment eliminate

cataracts?

Cataractogenesis

Denaturation of lens proteins

○ Physical disruption of lens fibers

Trauma

○ Altered osmotic gradients

Diabetes

○ Oxidative damage

Aging

○ Genetic predisposition

• Thirty dogs treated for at least 2 months

• Reduction of lens opacity in dogs with

immature cataract or nuclear sclerosis

• Owner reports “suggested” improved visual

behavior in 80% of cases

• In vitro

• Grapeseed extract

• Significant inhibition of mechanisms

of oxidative stress

• In vivo studies not yet presented

AJVR 2008

• Controlled study

• 12 months

• Drop given TID OU

• Significant inhibition of

cataract when given at

time of DM diagnosis

Questions???