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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???