Electroretinography is a prognostic indicator for postoperative vision in dogs undergoing retinal reattachment surgery.

PURPOSE: To determine whether pre-operative electroretinography (ERG) predicts postoperative vision in dogs undergoing retinal reattachment surgery (RRS). METHODS: This 18-month prospective study recorded signalment, duration, cause, and extent of retinal detachment and pre-operative vision status. Rod and mixed rod-cone ERG responses were recorded prior to RRS. Referring veterinary ophthalmologists assessed vision 2 months postoperatively. RESULTS: Thirty dogs (40 affected eyes) aged 4 months to 12.1 years were included. The detachment extent was 150° -320° in 15 of 40 eyes, 360° in 24 of 40 eyes, and not recorded in one eye. Most dogs had a genetic predisposition for retinal detachment. Eight eyes of seven dogs had previous cataract surgery. Mean estimated duration of detachment prior to surgery was 24.5 ± 19.6 days. Pre-operatively, 34 of 40 eyes were blind, two of 40 eyes were sighted, and four of 40 eyes had severely diminished vision. Compared to normative ERG values in our clinics, pre-operative ERGs were classified as "normal" in five of 40 eyes, "attenuated" in seven of 40 eyes, and "flat" in 28 of 40 eyes. Following RRS, the retina was fully reattached in all operated eyes. Two-month postoperatively, 30 of 40 eyes had "normal" vision as defined by referring veterinary ophthalmologists, six of 40 eyes had "limited" or "diminished" vision and four of 40 eyes were blind. Normal vision was regained in 12 of 12 (100%) of eyes with normal or attenuated pre-operative ERG's, but only in 18 of 28 (64%) of eyes with flat pre-operative ERG 's (Linear-by-linear test, P = 0.029). CONCLUSIONS: A recordable pre-operative ERG, even if attenuated, is associated with return of vision in canine RRS patients, and is a favorable prognostic indicator.

Outcome of retinal reattachment surgery in dogs: a retrospective study of 145 cases.

OBJECTIVE: To summarize the clinical outcomes and complications of pars plana vitrectomy with perfluoro-n-octane (PFO)-silicone oil exchange and endolaser retinopexy for treatment of retinal detachment (RD) in dogs, at one surgical center. PROCEDURE: Records of 145 dogs (168 eyes) that underwent retinal reattachment surgery (RR) between 2005 and 2009 were reviewed. All surgeries were performed by the same surgeon (SS). Data collected from the medical records included signalment, duration of time from diagnosis of RD to surgical intervention, if prior lensectomy was performed, time from surgery to restoration of vision, and postoperative complications. The data was analyzed to test the effect of breed, prior lensectomy, and time from diagnosis to surgery on visual outcome, tendency for complications, and time of complication onset. RESULTS: One hundred thirty pure-bred dogs (36 breeds) and 15 mixed-breed dogs were represented. One hundred fifty-five of 168 eyes (92%) were visual after surgery. Six of 155 eyes (3.8%) were visual before the procedure and retained vision; one hundred forty-nine of 155 eyes (96%) were nonvisual before and regained vision afterward. Thirteen of 168 eyes (8%) that were nonvisual prior to the procedure did not regain vision. The most common complications in order of occurrence included: cataract development, silicone prolapse into the anterior chamber, corneal ulceration, retinal degeneration, glaucoma, and uveitis. CONCLUSIONS: Pars plana vitrectomy with PFO-silicone oil exchange and endolaser retinopexy for treatment of RD in dogs is highly successful and associated with overall good visual outcome.

Qualitative tear film and conjunctival goblet cell assessment of cats with corneal sequestra.

OBJECTIVES: To evaluate the tear film qualitatively and conjunctival goblet cell numbers in cats with and without corneal sequestra. ANIMALS STUDIED AND PROCEDURES: This was a prospective evaluation of 11 cats with corneal sequestra and 14 control eyes that were either the contralateral normal eye when the sequestrum was unilateral or from control cats of similar age with no ocular disease. All cats in this study were examined by a veterinary ophthalmologist. The ophthalmic examinations included a neuro-ophthalmic evaluation, Schirmer tear tests, fluorescein staining, tear film break-up times, applanation tonometry, biomicroscopy, and indirect ophthalmoscopy. The palpebral conjunctiva at the dorsal nasal, ventral nasal, dorsal temporal and ventral temporal fornices were biopsied after topical anesthetic was applied to the cornea and conjunctiva. The conjunctival biopsies were fixed in formalin and sectioned routinely and stained with hematoxylin and eosin, and periodic acid-Schiff. These slides were examined by light microscopy by a blinded examiner. Goblet cell numbers were compared to conjunctival basal epithelial cell numbers by region. The goblet cell numbers by region from the eyes with sequestra was statistically compared to those from eyes without sequestra, with a student's paired t-test. Conjunctival swabs were collected from the cats with corneal sequestra and submitted for polymerase chain reaction for Herpes felis, Chlamydia psiitticia, and Mycoplasma felis. The corneal sequestra were removed by surgical keratectomy and fixed and stained routinely, and examined by light microscopy. RESULTS: No neurologic abnormalities were detected in any of the cats. The Schirmer tear tests (eyes with sequestra 14+/-5.1 mm/min; normal eyes 15+/-6.8 mm/min) and intraocular pressures (eyes with sequestra 21+/-6.6; normal eyes 22+/-5.8) were within normal reference ranges for cats. Biomicroscopic examinations revealed varied sizes and depths of brown- and amber-colored corneal sequestra. No abnormalities were noted on indirect ophthalmoscopic examinations. The tear film break-up time was 21 s (+/-12) for the normal eyes (n=14) and 14 s (+/-13) in eyes with corneal sequestra (n=11). The average goblet/epithelial cell ratios by region for the normal eyes and the eyes with sequestra respectively were 0.66, 0.56 for the dorsal nasal fornix, 0.68, 0.57 for the ventral nasal fornix, 0.63, 0.48 for the temporal dorsal fornix, and 0.55, 0.49 for the temporal ventral fornix. There were no significant differences in tear film break-up times and goblet cell numbers in eyes with corneal sequestra and those without sequestra. Three conjunctival swabs from two of 11 cats with sequestra were positive with PCR for Herpes felis virus. These included one cat with bilateral sequestra and one cat with unilateral corneal sequestrum. CONCLUSIONS: The pathogenesis of feline corneal sequestra does not appear to be linked primarily to abnormal goblet cell numbers, qualitative tear film abnormalities, and accelerated tear film break-up time.