Cataracts, Dr. Christa Corbett, 11/8/14
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Transcript of Cataracts, Dr. Christa Corbett, 11/8/14
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Christa Corbett, DVM, MS, DACVO
November 8, 2014
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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 ???
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Anatomy
AP
Zonules
Lens capsule
Nuclear vs. Cortical
Lens epithelium
Anterior
Produces new fibers
Equator
Active mitosis
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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
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RETROILLUMINATION
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Stages of Cataract
Incipient - <10%
Minor opacities, often incidental
Perfect view of fundus
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Stages of Cataract
Early immature – 10-50%
Obvious opacity, but good tapetal
reflex and good view of fundus
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Stages of Cataract
Late immature – 51-99%
Can still see tapetal reflex, but very
limited view of fundus
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Stages of Cataract
Mature – 100%
No tapetal reflex on retroillumination
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Stages of Cataract
Hypermature – resorbing
Varying degrees of lens opacity
Wrinkled capsule, “Sparkly” cataract
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And other minutia terms that
Ophthalmologists love . . .
Morgagnian – subset of hypermature
Cortex resorbs, nucleus drops
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And other minutia terms that
Ophthalmologists love . . .
Brunescence – Yellow!
Very old patients, very old cataracts
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And other minutia terms that
Ophthalmologists love . . .
Intumescence = FAT
Quick forming diabetic (occasionally
inherited)
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Tendency to progress
Nuclear: rarely progress
Cortical: variable, often progress
(esp. anterior)
Equatorial: often progress
AP
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Etiology
Inherited
Diabetes
Senile
Trauma
Uveitis
Horses
Cats
Nutrition
Irradiation
Hypo/Hyper Ca2+
Electrocution
Toxic
PRA
Drugs
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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
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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
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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.
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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
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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
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Retinal Testing
Outpatient testing, typically half-day
hospital stay
Sedation is rarely necessary
Retinal FUNCTION
Electroretinogram
Retinal STRUCTURE
Ocular ultrasound
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Retinal Testing
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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
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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
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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!
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Post-Operative Patient
Patients are immediately visual!
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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)
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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)
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Posterior Capsular Opacification
100% of dogs
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Minimal PCO in most cases!
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Hypermature cataract leading to
mineralized capsule plaques
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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)
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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
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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!
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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
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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
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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
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• 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
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• In vitro
• Grapeseed extract
• Significant inhibition of mechanisms
of oxidative stress
• In vivo studies not yet presented
AJVR 2008
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• Controlled study
• 12 months
• Drop given TID OU
• Significant inhibition of
cataract when given at
time of DM diagnosis
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Questions???