Page 352 - Cote clinical veterinary advisor dogs and cats 4th

148 Cataracts

visible, versus cataracts, which obstruct this
reflection.
VetBooks.ir flare. This will obstruct the ability to see
• Hyperlipidemia may result in lipid aqueous
the iris and pupil. Most common in the
miniature schnauzer.
• Diseases causing diffuse corneal edema (bluish
white opacity of the cornea, not in pupil, may
obstruct ability to see the pupil), including
glaucoma, anterior uveitis, and corneal
endothelial degeneration or dystrophy
• Diseases causing secondary cataracts
○ Retinal degeneration or detachment
○ Anterior uveitis (cataracts typically
incomplete if due to inflammation; uveitis
may also occur secondary to cataracts; if
cataracts occupying large extent of lens in
predisposed breed, assume lens-induced
uveitis) (p. 1023)
○ Lens luxation (p. 581) CATARACTS Canine eye 6 months after cataract surgery and foldable, acrylic intraocular lens implantation.
The pupil has been dilated, and the lens implant (arrows) is centered within the pupil.
Initial Database
• Complete ophthalmic examination (p. 1137), rate and eyes left untreated have a 255 ○ Use IOP-lowering drugs in combination
including times greater failure rate. with antiinflammatories if secondary
○ Menace response, maze test, dazzle reflex ○ Referral to a veterinary ophthalmologist glaucoma develops.
○ Evaluation of pupil size, symmetry, and will help in triage, diagnosis, and treat- ○ Enucleation or evisceration and intrascleral
pupillary light reflexes ment of cataracts. prosthesis for end-stage, blind, painful
○ Intraocular pressure (IOP): rule out globes
glaucoma (>20-25 mm Hg) Acute General Treatment
○ After IOP assessment (assuming normal • Treat or prevent associated secondary uveitis Drug Interactions
result), dilate pupil with 1% tropicamide with topical mydriatics and antiinflamma- Corticosteroids (topical ophthalmic or especially
○ Penlight, transilluminator, or mon- tories (p. 1023). oral) may interfere with management of diabetes
ocular slit lamp (Heine) to characterize • Treat secondary glaucoma accordingly (p. mellitus.
the cataract, evaluate for concurrent 387).
uveitis • Referral for cataract surgery if cataract is Possible Complications
○ Fundic (posterior segment) examination vision threatening and animal systemically • Without cataract surgery, the follow-
• Blood and urine glucose determination (dogs stable (e.g., diabetes mellitus is controlled). ing can occur: uveitis, glaucoma, lens
primarily) ○ Cataract surgery requires preliminary luxation, retinal detachment, blindness.
ocular ultrasound and electroretinogram The risk of these is significantly decreased
Advanced or Confirmatory Testing that indicate the posterior segment of the with administration of long-term topical
• CBC, serum biochemistry profile, and eye is normal. antiinflammatories.
urinalysis to rule out systemic metabolic ○ Phacoemulsification (ultrasonic lens • After cataract surgery, the following can occur:
disease (e.g., diabetes mellitus, hypocalcemia) fragmentation) to remove the cataract uveitis, glaucoma, corneal ulceration, surgical
as cause of cataracts and/or to assess patient ■ Followed by implantation of an arti- wound/incisional dehiscence, intraocular
before considering referral for possible ficial intraocular lens (IOL) to restore infection, retinal detachment, IOL displace-
cataract surgery emmetropia (normal vision, neither ment, lens capsule fibrosis (lessened by the
• Ocular ultrasound if the cataract is immature far-sighted nor near-sighted) use of new foldable, acrylic IOL implants),
or worse in severity and precludes accurate ■ Without an IOL implant, animals are corneal endothelial degeneration and second-
evaluation of the posterior segment of the 14 diopters hyperopic (far-sighted) with ary corneal edema, keratoconjunctivitis sicca
eye little useful vision. (KCS).
• Electroretinogram to assess retinal function • Dogs with diabetes mellitus are at increased
(routinely conducted by veterinary ophthal- Chronic Treatment risk for chronic uveitis, KCS, facial nerve
mologists before cataract surgery) • After cataract surgery, treat as directed by palsy, Horner’s syndrome, corneal ulceration,
the veterinary ophthalmologist. retinal detachment secondary to systemic
TREATMENT ○ Topical antibiotics and antiinflammatories hypertension, and retinal petechiae resulting
○ Exercise restriction/Elizabethan collar: 2 from diabetic retinopathy.
Treatment Overview weeks
• Incipient and nonprogressive early immature ○ Antiinflammatory therapy may be contin- Recommended Monitoring
cataracts do not require immediate treatment, ued in a decreasing fashion for months • Without cataract surgery, monitor for cataract
but must be monitored for progression. or, in some cases (diabetics), indefinitely. progression and secondary complications
• Progressive immature, mature, and hyper- ○ Frequent re-evaluation of IOL posi- (see Possible Complications above) q 2-4
mature cataracts are treated to tion, IOP, Schirmer tear test (diabetics months or more or less frequently, depending
○ Restore vision (i.e., cataract surgery) especially), retinal examination, and on the extent of cataract, rate of cataract
○ Prevent secondary sequelae of cataracts: inflammation control development, and presence or absence of
uveitis, glaucoma, and retinal detachment. • If cataract surgery is not an option associated ocular complications.
When compared to surgically treated eyes, ○ Monitor cataracts for progression, and • After cataract surgery, monitor according to
eyes managed with topical antiinflamma- treat prophylactically for secondary uveitis veterinary ophthalmologist’s recommenda-
tories alone have 4 times greater failure, with topical antiinflammatories long term. tions; generally, involves re-evaluations

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