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- Author or Editor: Paul E. Miller x
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Abstract
Objective—To determine factors contributing to glaucoma after lens extraction via phacoemulsification in dogs.
Design—Retrospective study.
Animals—22 dogs (29 eyes) with glaucoma and 21 dogs (30 eyes) without glaucoma after phacoemulsification.
Procedure—Medical record review.
Results—Eyes at increased risk for glaucoma included those of Boston Terriers, those with uveal or retinal abnormalities before surgery, and those with intraoperative intraocular hemorrhage. Significant differences between groups were not detected for incidence of preoperative lens-induced uveitis, presence of an intraocular lens, or frequency of an acute postoperative increase in intraocular pressure. Glaucoma developed (mean ± SD) 12.8 ± 14.1 months (median, 10 months; range, 0.25 to 55 months) after surgery.Eighteen of 29 (62%) eyes with potential for vision after onset of glaucoma retained vision for a mean of 16.5 ± 12.8 months (median, 10.8 months; range, 1.5 to 37 months) after glaucoma was diagnosed. Most of these eyes still had vision at the conclusion of the study period.
Conclusions and Clinical Relevance—Risk factors identified by this study will aid in preoperative counseling of clients and refining selection criteria for candidates for phacoemulsification. Careful follow-up for the remainder of the dog's life after surgery may improve long-term success rates by permitting early intervention before intraocular pressure increases substantially and vision is irreversibly lost. Surgery for cataracts may still be worthwhile in dogs with increased risk of glaucoma, especially if elderly, because of the lengthy period to onset of glaucoma after surgery and the beneficial effects of treatment after glaucoma develops. ( J Am Vet Med Assoc 2001; 218:70–76)
Abstract
Objective—To evaluate the usefulness of high-resolution ultrasonography (HRUS) for measurements of anterior segment structures in canine eyes.
Animals—4 clinically normal Beagles.
Procedure—Images were obtained from 8 eyes with a handheld 20-MHz transducer. Eleven anterior segment structures on each image were measured 5 times by 2 independent observers. Coefficients of variation (CVs) for measurements were used to assess intraobserver reliability. Interobserver reliability was assessed by comparing measurements obtained by the 2 observers from the same images. Five images were sequentially obtained from 2 locations (ie, superior and temporal) to evaluate image reproducibility. Anterior segment structures were measured once on each image; image reproducibility was assessed by use of the CV for each parameter measured. Imaging location was assessed by comparison of CV for measurements from each location.
Results—CVs were < 10% for observer A for all measurements except the ciliary cleft area (11.63%). The CVs were > 10% for observer B for measurements of the angle recess area (18.51%) and ciliary cleft width (17.44%) and area (16.01%). Significant differences in measurements between observers were found for 5 of 11 anterior segment structures. Imaging the superior aspect of the globe provided the most reproducible images, although image reproducibility was still somewhat variable, with the highest and lowest CVs for measurements of 33.01% and 11.32%, respectively, in the superior position.
Conclusions and Clinical Relevance—High-resolution ultrasound images can be used to reliably measure various anterior segment structures. Clinically relevant findings in the anterior segment of canine eyes may be detectable by use of HRUS. (Am J Vet Res 2005;66:1775–1779)
Abstract
Objective—To determine effects after topical administration of latanoprost, timolol, or a commercially available latanoprosttimolol combination twice daily on intraocular pressure (IOP), pupil size (PS), and heart rate (HR) in clinically normal dogs.
Animals—17 clinically normal dogs.
Procedures—A randomized controlled clinical trial was performed with a treatment (n = 9) and saline (0.9% NaCl) solution group (8). Each dog in the treatment group received 3 treatments (latanoprost, timolol, and the latanoprost-timolol combination), with a 14-day washout period between treatments. Baseline values were established on day 1 of each treatment period. On days 2 through 5, drugs were administered topically every 12 hours to 1 eye of each dog in the treatment group. In both groups, IOP PS, and HR were measured at 0, 2, 4, 6, 8, and 9 hours on days 2 and 5.
Results—Eyes treated with latanoprost or the latanoprost-timolol combination had a significant decrease in IOP and a significantly smaller PS, compared with results for dogs receiving only timolol or dogs in the saline solution group. Timolol and the latanoprost-timolol combination both significantly lowered HR, compared with HR following administration of latanoprost and the saline solution.
Conclusions and Clinical Relevance—Topical administration of latanoprost alone was as effective at lowering IOP as was administration of the latanoprost-timolol combination when both were given every 12 hours to clinically normal dogs. Timolol, either alone or in combination with latanoprost, appeared to have little or no effect on IOP in clinically normal dogs but was associated with a reduction in HR. (Am J Vet Res 2010;71:1055–1061)
Abstract
Objective—To determine intraocular pressure (IOP) in cats ≥ 7 years of age undergoing a routine comprehensive geriatric health examination.
Design—Prospective study.
Animals—538 cats (1,068 eyes).
Procedure—IOP was measured by applanation tonometry following instillation of 0.5% proparacaine.
Results—Mean ± SD IOP for all eyes was 12.3 ± 4.0 mm Hg (range, 4 to 31 mm Hg). Mean age was 12.3 ± 2.9 years. Intraocular pressure did not vary significantly cross-sectionally with age. However, in 78 cats, IOP was measured more than once, and follow-up measurements were significantly less than initial measurements (mean time between measurements, 9.4 ± 3.0 months). The most useful tonometric criteria for identifying ocular abnormalities on the basis of IOP was an IOP ≥ 25 mm Hg (mean + 3 SD) or a difference in IOP between eyes ≥ 12 mm Hg. Eight cats met these criteria, and 5 of these cats had ophthalmic abnormalities. Low IOP was a nonspecific indicator of the presence of ocular abnormalities, as 111 cats had an IOP ≤ 8 mm Hg, but only 2 had uveitis.
Conclusions and Clinical Relevance—Results suggest that IOP measurements can be a useful addition to a comprehensive geriatric health examination in cats ≥ 7 years of age, especially when combined with an ophthalmic examination. Cats without ocular abnormalities that have IOP ≥ 25 mm Hg or a ≥ 12 mm Hg difference in IOP between eyes should have tonometry repeated or be referred to an ophthalmologist for further evaluation before beginning antiglaucoma treatment. (J Am Vet Med Assoc 2001;219: 1406–1410)
Abstract
Objective—To investigate cellular death in the neurosensory portion of the retina during the first 7 days after onset of clinical signs of overt primary angle-closure glaucoma (PACG) in dogs.
Sample Population—14 globes from dogs with PACG and 2 normotensive globes from dogs with PACG in the opposite eye.
Procedures—Retinas were examined via light microscopy and terminal deoxynucleotidyl transferase- mediated biotin-dUTP nick end-labeling.
Results—Necrosis of ganglion cells and segmental degeneration of the nerve fiber layer rapidly progressed to scattered full-thickness retinal attenuation and disorganization. Apoptosis was detectable within 1 day after onset of PACG and was prominent by 3 days. Necrosis of ganglion cells was significantly greater in retinas affected for ≤ 1 day, compared with retinas affected for > 1 day. In contrast, apoptosis in the ganglion cell layer was significantly greater in retinas affected for > 1 day, compared with retinas affected for ≤ 1 day. End-stage retinal atrophy was seen by day 7.
Conclusions and Clinical Relevance—The presence of necrotic ganglion cells within 1 day after onset of clinical signs suggests a narrow window of opportunity to initiate effective therapy in overt PACG. Photoreceptor death is an important and striking aspect of neurosensory retinal degeneration after acute onset of PACG. (Am J Vet Res 2002;63:257–261)
Abstract
OBJECTIVE To evaluate potential risk factors for development of primary angle-closure glaucoma (PACG) in Bouviers des Flandres.
DESIGN Prospective, observational study.
ANIMALS 98 Bouviers des Flandres.
PROCEDURES All dogs underwent slit-lamp biomicroscopy, indirect ophthalmoscopy, gonioscopy, applanation tonometry, streak retinoscopy, and A-scan, B-scan, and high-resolution ultrasonography. Iridocorneal angles and degree of pectinate ligament dysplasia sheeting were graded, and an angle index was mathematically derived for each eye on the basis of these values. Ciliary clefts evaluated by high-resolution ultrasonography were classified as open, narrow, or closed. Owners were contacted by telephone 7 to 9 years after the initial examination to determine whether dogs had a subsequent diagnosis of PACG. Relationships between previously recorded variables and the development of PACG were evaluated by logistic regression methods. Available pedigrees were reviewed to assess genetic relationships among affected dogs.
RESULTS 9 of 92 (9.8%) dogs with follow-up information available developed PACG. An angle index < 1 and presence of a narrow or closed ciliary cleft in 1 or both eyes were each significantly associated with development of PACG. Odds of developing PACG for dogs with an angle index < 1 (indicating marked reduction in outflow capacity through the iridocorneal angle), a narrow or closed ciliary cleft in > 1 eye, or both findings were 13, 20, and 28 times those for dogs that did not have these findings, respectively. All dogs that developed PACG shared 1 common male sire or grandsire.
CONCLUSIONS AND CLINICAL RELEVANCE Several anatomic factors were significant risk factors for development of PACG in this population of dogs. Results also suggested a genetic component for the disease.
Abstract
Objective—To compare intraocular pressure (IOP) measurements obtained with a rebound tonometer in dogs and horses with values obtained by means of applanation tonometry and direct manometry.
Design—Prospective study.
Animals—100 dogs and 35 horses with clinically normal eyes, 10 enucleated eyes from 5 dogs, and 6 enucleated eyes from 3 horses.
Procedures—In the enucleated eyes, IOP measured by means of direct manometry was sequentially increased from 5 to 80 mm Hg, and IOP was measured with the rebound tonometer. In the dogs and horses, results of rebound tonometry were compared with results of applanation tonometry.
Results—For the enucleated dog and horse eyes, there was a strong ( r2 = 0.99) linear relationship between pressures obtained by means of direct manometry and those obtained by means of rebound tonometry. Mean ± SD IOPs obtained with the rebound tonometer were 10.8 ± 3.1 mm Hg (range, 5 to 17 mm Hg) and 22.1 ± 5.9 mm Hg (range, 10 to 34 mm Hg) for the dogs and horses, respectively. Mean IOPs obtained with the applanation tonometer were 12.9 ± 2.7 mm Hg (range, 8 to 18 mm Hg) and 21.0 ± 5.9 mm Hg (range, 9 to 33 mm Hg), respectively. Values obtained with the rebound tonometer were, on average, 2 mm Hg lower in the dogs and 1 mm Hg higher in the horses, compared with values obtained with the applanation tonometer.
Conclusions and Clinical Relevance—Results suggest that the rebound tonometer provides accurate estimates of IOP in clinically normal eyes in dogs and horses. (J Am Vet Med Assoc 2005;227:244–248)
Abstract
Objective—To assess the refractive state of eyes in various breeds of dogs to identify breeds susceptible to ametropias.
Animals—1,440 dogs representing 90 breeds.
Procedures—In each dog, 1 drop of 1% cyclopentolate or 1% tropicamide was applied to each eye, and a Canine Eye Registration Foundation examination was performed. Approximately 30 minutes after drops were administered, the refractive state of each eye was assessed via streak retinoscopy. Dogs were considered ametropic (myopic or hyperopic) when the mean refractive state (the resting focus of the eye at rest relative to visual infinity) exceeded ± 0.5 diopter (D). Anisometropia was diagnosed when the refractive error of each eye in a pair differed by > 1 D.
Results—Mean ± SD refractive state of all eyes examined was −0.05 ± 1.36 D (emmetropia). Breeds in which the mean refractive state was myopic (≤ −0.5 D) included Rottweiler, Collie, Miniature Schnauzer, and Toy Poodle. Degree of myopia increased with increasing age across all breeds. Breeds in which the mean refractive state was hyperopic (≥ +0.5 D) included Australian Shepherd, Alaskan Malamute, and Bouvier des Flandres. Astigmatism was detected in 1% (14/1,440) of adult (≥ 1 year of age) dogs; prevalence of astigmatism among German Shepherd Dogs was 3.3% (3/90). Anisometropia was detected in 6% (87/1,440) of all dogs and in 8.9% (8/90) of German Shepherd Dogs.
Conclusions and Clinical Relevance—Refractive states of canine eyes varied widely and were influenced by breed and age. In dogs expected to have high visual function (eg, performance dogs), determination of refractive state is recommended prior to intensive training.
