Keratometry, biometry, and prediction of intraocular lens power in adult tigers (Panthera tigris).

OBJECTIVE: To calculate the necessary pseudophakic intraocular lens (IOL) power to approximate emmetropia in adult tigers. ANIMALS: 17 clinically normal adult tigers. PROCEDURES: 33 eyes of 17 clinically normal adult tigers underwent routine ophthalmic examination and B-scan ultrasonography while anesthetized for unrelated procedures. Specific ultrasound data (globe measurements and corneal curvature) and estimated postoperative IOL positions were utilized to calculate predicted IOL power by use of Retzlaff and Binkhorst theoretical formulas. Applanation tonometry and refraction were also performed. RESULTS: Mean ± SD axial globe length was 29.36 ± 0.82 mm, preoperative anterior chamber depth was 7.00 ± 0.74 mm, and crystalline lens thickness was 8.72 ± 0.56 mm. Mean net refractive error (n = 33 eyes) was +0.27 ± 0.30 diopters (D). By use of the Retzlaff formula, mean predicted IOL power for the postoperative anterior chamber depth (PACD), PACD - 2 mm, and PACD + 2 mm was 43.72 ± 4.84 D, 37.62 ± 4.19 D, and 51.57 ± 5.72 D, respectively. By use of the Binkhorst equation, these values were 45.11 ± 4.91 D, 38.84 ± 4.25 D, and 53.18 ± 5.81 D, respectively. Mean intraocular pressure for all eyes was 14.7 ± 2.69 mm Hg. CLINICAL RELEVANCE: The calculated tiger IOL was lower than reported values for adult domestic felids. Further studies evaluating actual PACD and pseudophakic refraction would help determine the appropriate IOL power to achieve emmetropia in this species.

Pharmacologic ciliary body ablation for chronic glaucoma in dogs: A retrospective review of 108 eyes from 2013 to 2018.

OBJECTIVE: To evaluate the long-term outcome and efficacy of intravitreal injection of gentamicin and dexamethasone sodium phosphate (IVGD) or triamcinolone in end-stage glaucoma patients and determine pre-procedure prognostic indicators of success and post-operative complications. PROCEDURE: Medical records were reviewed for 108 dogs (108 eyes) treated with intravitreal gentamicin with or without dexamethasone sodium phosphate or triamcinolone for glaucoma between 2013 and 2018 with 3 months of minimum follow-up. Signalment and clinical findings, including type of glaucoma, pre-procedure intraocular pressure (IOP), chronicity, procedure protocol, and outcome were recorded. Success was defined as an intraocular pressure of ≤25 mm Hg at the time of last re-examination or no ocular hypotensive medications at 3 months or longer post-injection. RESULTS: The overall success rate for pharmacologic ablation was 95%. The success rate for dogs receiving no ocular hypotensive medications was 86%. Seventy-six eyes (70.4%) had primary glaucoma, and 32 eyes (29.6%) had secondary glaucoma. Age at the time of injection had no effect on initial success but did in final success (P =-.03) for dogs requiring repeat injections. Cocker Spaniels required the most repeat 2nd and 3rd injections (3/12 dogs) and (2/4 dogs), respectively. No preoperative variable significantly affected the success rate. The most common complications were phthisis bulbi (59.2%), corneal edema (25.9%), and ulcerative keratitis (22.3%). Uncontrolled IOP resulted in enucleation in two dogs (1.8%). CONCLUSIONS: Pharmacologic ablation has a high overall success rate in lowering IOP to ≤25 mm Hg short-term in blind, glaucomatous canine eyes. Type of glaucoma, pre-procedure IOP, chronicity, and protocol did not affect success.

A retrospective analysis of lipid-laden aqueous humor in dogs: Thirty cases.

OBJECTIVE: To describe the clinical presentation and outcome of canine patients that present with lipid-laden aqueous humor (LLA) and to evaluate its association with other ocular and systemic disorders. METHODS: Medical records were identified and reviewed of 30 dogs presenting with clinical signs of LLA between 2013 and 2017 and compared to the canine referral population during the same time period. The percentage of dogs affected by LLA and potential risk factors were compared between groups. RESULTS: There were 40 eyes in 30 dogs with LLA out of 8011 (0.4%) referrals. The mean age of dogs with LLA was significantly younger than dogs without LLA (P = .0334). Sex was not associated with LLA. Miniature Schnauzers were more likely to have LLA than mixed breeds (P < .0001). Incidence of LLA was significantly higher in eyes also affected by corneal ulceration (P = .0018) or phacoemulsification (P = .0001). Sixty-two percent and 51% of dogs with LLA had concurrent diabetes mellitus and hypertriglyceridemia, respectively. Average triglyceride level of dogs with LLA was 1087 mg/dL (±544) (reference 50-150 mg/dL) and average cholesterol level was 575 mg/dL (±232) (reference 125-300 mg/dL). Complete resolution of LLA was achieved in all dogs re-examined with an average of 20.2 days (range 4-175 days) after diagnosis. There were 6/30 dogs lost to follow-up. Recurrence of LLA occurred at least once in 4/24 dogs (16.7%) after resolution. CONCLUSIONS: Lipid-laden aqueous humor occurs more frequently in Miniature Schnauzers. Corneal ulceration and phacoemulsification are risk factors. Complete resolution was seen in all cases with a low incidence of recurrence.

Retrospective analysis of ocular neuropathies in diabetic dogs following cataract surgery.

OBJECTIVES: To describe and compare the cumulative incidence and clinical progression of ocular neuropathies in diabetic dogs vs nondiabetic dogs following cataract surgery. METHODS: Medical records of 196 diabetic and 442 nondiabetic dogs who underwent cataract surgery between 2004 and 2015 were reviewed. The percentage of patients affected by neuropathy and potential risk factors were compared between groups. RESULTS: Patients with diabetes mellitus (DM) were 20.4 times more likely to develop an ocular neuropathy than patients without DM (12.24% vs 0.68%). Twenty-four diabetic patients were affected by mononeuropathies or polyneuropathies including Horner's syndrome (n = 20), facial neuropathy (n = 5), and neurogenic keratoconjunctivitis sicca (NKCS) (n = 5). The odds of a diabetic patient developing Horner's syndrome and NKCS were 86.3 and 20.7 times higher than a nondiabetic patient, respectively. The average duration of DM prior to diagnosis of neuropathy was 659 days (range 110-2390 days; median 559 days). Complete resolution was achieved in 10 of 22 neuropathies (45%) within an average of 248 days (range 21-638 days; median 187 days) after diagnosis. CONCLUSIONS: The odds of developing an ocular neuropathy, specifically Horner's syndrome and NKCS, are statistically higher in diabetic patients compared to nondiabetic patients. Neuropathies were observed as a long-term complication in this group of diabetic patients, and complete resolution of the neuropathy was observed in less than half of the affected population.

Electroretinographic changes after intravenous lipid emulsion therapy in a dog and a foal with ivermectin toxicosis.

This case report describes ivermectin-induced blindness in a dog and a foal with normal ophthalmic fundic examinations and attenuated electroretinography (ERG). Subsequent recovery in ERG was noted following intravenous lipid emulsion (ILE) therapy. A dog and a foal were evaluated for ivermectin-induced blindness. Clinical signs included dull mentation, absent pupillary light reflexes (PLRs), and absent menace on presentation. The animals had normal fundoscopic examinations; however, in both cases ERG was consistent with neurosensory retinal dysfunction. Following ILE therapy for ivermectin toxicosis, return of menace, PLRs, and normal mentation were noted, as was improvement in ERG and serum ivermectin levels. These are the first documented cases of ivermectin-induced blindness in a dog and a foal with normal fundic examinations and attenuated ERG. ERG improved in both animals after ILE therapy. ERG may assist in the diagnosis of ivermectin toxicosis in dogs and horses. ILE therapy may hasten recovery in treatment of ivermectin-induced blindness.

Retinal detachment and glaucoma in the Boston Terrier and Shih Tzu following phacoemulsification (135 patients): 2000-2014.

OBJECTIVES: To report the cumulative incidence of retinal detachment (RD) and glaucoma following phacoemulsification in Boston Terriers and Shih Tzu in the southeastern United States over a 14-year period and investigate the potential predisposing risk factors. METHODS: Medical records of 83 Shih Tzu and 52 Boston Terriers that underwent phacoemulsification between 2000 and 2014, with or without intraocular lens placement, were reviewed. For a comparison population, phacoemulsification data from 45 Labrador Retrievers, 73 Schnauzers, and 159 Bichon Frises were evaluated. Information collected included signalment, concurrent systemic diseases, preoperative findings, surgical details, postoperative complications, and duration of follow-up. Percentages of patients to develop RD and glaucoma were assessed, as well as potential risk factors. Minimum of 3 months of follow-up after surgery was required for inclusion. RESULTS: Retinal detachment occurred in 7.7% (7/91 eyes) and 8.9% (11/123 eyes) and glaucoma occurred in 38.0% (35/91 eyes) and 29.3% (36/123 eyes) of Boston Terriers and Shih Tzu, respectively. Mean follow-up time was 804 days. Neither Boston Terriers nor Shih Tzu were at increased risk for RD or glaucoma when compared to the other breeds, and no significant risk factors for either breed were identified in the final multivariate analysis. CONCLUSIONS: The cumulative incidence of RD in Boston Terrier and Shih Tzu reported here was in agreement with previously reported nonbreed specific percentages (2.7-8.4%). The cumulative incidence of glaucoma in this population of Boston Terriers and Shih Tzu was higher than previously reported nonbreed specific percentages (5.1-18.8%).

Ophthalmic diagnostic testing and examination findings in a colony of captive brown pelicans (Pelecanus occidentalis).

OBJECTIVE: To establish reference values and report ophthalmic examination findings in a colony of captive brown pelicans (Pelecanus occidentalis). DESIGN: Descriptive study. ANIMALS STUDIED: Sixty-three captive brown pelicans in Florida were examined. PROCEDURES: A complete ophthalmic examination including Schirmer tear test (STT), applanation tonometry, fluorescein stain, biomicroscopy, and direct and indirect ophthalmoscopy was performed. A-scan ultrasonography was performed to measure axial globe length (AGL), anterior chamber depth (ACD), lens thickness, and vitreal chamber length. Fifty-two adults and 11 juvenile pelicans with an age range of 4 months to 38 years were evaluated. RESULTS: Twenty-nine pelicans (46%) had a normal ocular examination. Mean STT in normal pelicans was 5.45 ± 1.88 mm/min. Mean intraocular pressure (IOP) in normal pelicans was 10.86 ± 1.61 mmHg. One pelican was fluorescein positive unilaterally. Mean AGL was 20.70 ± 0.62 mm. Mean ACD was 3.38 ± 0.19 mm. Mean axial lens diameter (ALD) was 5.19 ± 0.23 mm. Mean vitreal chamber depth (VCD) was 12.15 ± 0.53 mm. Twenty-three pelicans (36.51%) had cataracts, 17 pelicans (26.98%) had vitreal degeneration, 18 pelicans (28.57%) had corneal disease, and seven pelicans (11.11%) had evidence of significant ocular trauma, which included collapsed anterior chamber or lens luxation. CONCLUSIONS AND CLINICAL RELEVANCE: To the author's knowledge, this is the first report of normal ophthalmic parameters and the incidence and type of ocular disease in a captive flock of brown pelicans. This information may aid in the diagnosis and treatment of brown pelicans with ocular disease.

Use of a nictitating membrane flap for treatment of feline acute corneal hydrops-21 eyes.

OBJECTIVE: To evaluate the effectiveness of the use of a nictitating membrane flap (NMF) as therapy in 19 cats (21 eyes) affected with feline acute corneal hydrops (FACH). METHODS: Medical records from 19 cats diagnosed with FACH and treated with a NMF were retrospectively evaluated. Information was collected from multiple veterinary hospitals and included signalment, medical history, therapy, and ocular outcome. RESULTS: Breeds included 13 Domestic Shorthairs, 2 Exotic Shorthairs, 2 Maine Coons, 1 Persian, and 1 Domestic Medium Hair. Two cats were bilaterally affected. Median age of cats was 3.2 years (range 0.26-15 years). Eleven patients were spayed females, 6 were neutered males, and 2 were intact males. Topical steroids were previously administered in 5 (23.8%) eyes; oral steroids were previously administered in 7 cats (36.8% of patients); three patients received both oral and topical steroids. Thirteen of 21 (61.9%) eyes had a history of ocular disease including ulcerative and nonulcerative keratitis, anterior uveitis, corneal sequestrum, conjunctivitis, and glaucoma. Median duration of NMF was 15 days (range 6-30 days). Follow-up ranged from 12 to 1601 days (median 169 days). Corneal perforation occurred in 1 (4.7%) eye and was successfully repaired. One lesion (4.7%) in a diabetic patient did not resolve. Nineteen of the treated eyes (90.5%) resolved with no complications. CONCLUSIONS: A nictitating membrane flap successfully treated 90.5% of FACH eyes (89.5% of patients).

Modified lamellar keratoplasties for the treatment of deep stromal abscesses in horses.

OBJECTIVE: To describe a surgical modification of deep lamellar endothelial keratoplasty (DLEK) and posterior lamellar keratoplasty (PLK) procedures, to facilitate surgery on standing horses under-sedation. ANIMALS STUDIED: Four client-owned horses, for which the owners declined surgery under general anesthesia, underwent standing corneal lamellar keratoplasty procedures for the treatment of deep corneal stromal abscesses. PROCEDURES: All four horses were placed in stocks and sedated with detomidine. Local eyelid and retrobulbar blocks were performed to provide local analgesia and akinesia, and each horse's head was stabilized and supported by soft pads placed on a mobile cart. Deep lamellar endothelial keratoplasties (DLEKs) and posterior lamellar keratoplasties (PLKs) were performed on two horses each, for the treatment of deep stromal abscesses (DSA). Following the first DLEK, a mid-stromal two-step anterior lamellar keratectomy modification was used to facilitate rapid closure of the anterior chamber immediately following removal of the abscess. RESULTS: Each of the four horses had similar cosmetic and postoperative visual outcomes, compared to previously published results. Intra-operative complications were most prevalent in the first DLEK case (i.e., focal iris and lens damage and postoperative anterior chamber collapse) and were all but eliminated in the remaining three cases. Similar to previously reported findings, greater postoperative corneal fibrosis was observed in the DLEK cases. CONCLUSIONS: In horses with deep stromal or endothelial abscesses, for which general anesthesia is not an option, both the modified DLEK and PLK corneal procedures may be performed as an alternative to enucleation on the standing, sedated horse.

The effects of intravenous romifidine on intraocular pressure in clinically normal horses and horses with incidental ophthalmic findings.

DESIGN: Original study. OBJECTIVE: To evaluate the effect of sedation with romifidine hydrochloride 1% (Sedivet: Boehringer-Ingelheim) on intraocular pressure (IOP) in the normal horse and horses with incidental ophthalmic findings as measured by applanation tonometry. ANIMALS: Nineteen clinically normal horses (13 geldings, six mares) and eight horses (three geldings, five mares) with incidental ophthalmic findings were included in this study. PROCEDURES: All horses underwent complete ophthalmic examination with pharmacologic mydriasis a minimum of 2 weeks prior to IOP evaluation. Baseline intraocular pressure values were obtained following auriculopalpebral nerve block and topical anesthetic. Immediately thereafter, romifidine was administered intravenously (75 µg/kg) and the IOP recorded at 5, 15, 30, 45 and 60 min postsedation in both eyes. Five successive readings were obtained at each time point, the low and high value discarded, and three remaining readings averaged for a mean. RESULTS: The changes with time were consistent between eyes and OD and OS results were pooled. The mean IOP at baseline was 26.35 ± 5.57 mmHg. Mean IOP values were significantly lower than baseline at 5 (P < 0.0001), 15 (P < 0.0001), 30 (P = 0.0003), 45 (P < 0.0001) and 60 (P = 0.0005) minutes. The largest change from baseline (16.7%) was noted at t = 15 min. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of romifidine significantly decreased the IOP from baseline at all time points measured. The greatest decline in IOP was noted at 15 min postsedation. Results are consistent with other studies noting a decline in IOP with administration of α-2 agonists.

Treatment of nonhealing corneal ulcers in 60 horses with diamond burr debridement (2010-2013).

OBJECTIVE: To review the signalment, clinical characteristics, and outcome of horses with nonhealing corneal ulcers treated with diamond burr debridement (DBD); and to evaluate the role of ulcer duration, size and location, and bandage contact lens (BCL) placement on healing. ANIMALS: From January 2012-April 2013, 60 horses were diagnosed with ulcers classified as nonhealing based on the presence of raised epithelial margins and duration of at least 7 days. PROCEDURE: Retrospective record review. RESULTS: Average age of included horses was 14.68 years, SD 8.17 years. There were three times as many males (45) as females (15), (χ12 = 15, P = 0.001). Forty-eight horses (80%) had nonhealing ulcers uncomplicated by associated corneal disease. In the remaining horses, associated corneal disease included esinophilic keratitis (10%), calcific band keratopathy (5%), endothelial decompensation (1.67%), habronemiasis(1.67%), and lid suture abrasion (1.67%). Average corneal ulcer duration prior to diamond burr debridement (DBD) was 29.0 days (n = 56). Ulcers occurred most commonly in the axial cornea (41%). Fifty-five of 60 horses (92%) healed with DBD. Healing time, defined as time to epithelialization following DBD, averaged 15.5 days, SD 9.32 days, and was not correlated with patient age or ulcer duration, location, or size prior to or following DBD. Healing time was significantly longer for eyes in which a BCL had been placed (n = 28, 19.0 days) than for eyes without a BCL (n = 32, 12.9 days), F(1,58) = 5.543, P = 0.02. DBD was considered a failure for five horses (8%). CONCLUSIONS: DBD may be an effective treatment for nonhealing corneal ulcers in horses.

Carbon dioxide laser photoablation adjunctive therapy following superficial lamellar keratectomy and bulbar conjunctivectomy for the treatment of corneolimbal squamous cell carcinoma in horses: a review of 24 cases.

OBJECTIVE: To determine the complications and nonrecurrence rates following superficial lamellar keratectomy, bulbar conjunctivectomy, and adjunctive carbon dioxide (CO(2)) photoablation for corneolimbal squamous cell carcinoma (SCC) in the horse. STUDY DESIGN: Retrospective study. Sample population Twenty-four horses with corneolimbal SCC. PROCEDURE: Medical records of horses diagnosed with corneolimbal SCC that was surgically excised and where CO(2) photoablation was used as an adjunctive therapy from 2000 to 2007 were reviewed. Signalment, prior therapy, tumor location and size, complications, and recurrence of SCC were recorded. RESULTS: The Thoroughbred was the most commonly (25%) represented breed. Lesions were >10 mm in diameter in 70.8% of cases. Eight horses (33.3%) had neoplastic cells extending to the deep margin of the keratectomy. All horses were available for follow-up for an average ± standard deviation of 40.7 ± 25 months. Four horses (16.7%) developed a recurrence of SCC. Three of these four horses underwent repeat keratectomy and CO(2) photoablation, one each, at 4 months, 1, and 2 years following the initial procedure. One horse underwent enucleation 8 months following the initial procedure. CONCLUSIONS AND CLINICAL RELEVANCE: As an adjunctive therapy, CO(2) photoablation was successful in 87.5% of the horses following a single procedure and in a total of 91.7% following a second therapeutic application. CO(2) photoablation appears to be effective as an adjunctive therapy following removal of large corneolimbal SCC in the horse and in cases in which all tumor cells were not excised.

Surgical correction of severe strabismus and enophthalmos secondary to zygomatic arch fracture in a dog.

A grossly displaced segmental zygomatic arch fracture with marked ventro-lateral deviation of the left globe was diagnosed in a 3-month-old male German Shepherd dog following a bite injury. The fracture was approached via a modified lateral orbitotomy and a fragment of the lacrimal bone removed. The rostral portion of the fracture was stabilized with a 5-hole 2.0 dynamic compression plate bone plate. The surgical correction achieved sufficient skeletal fixation for proper anatomical reduction of the globe and excellent cosmetic and functional outcomes.

Effect of ophthalmic Nd:YAG laser energy on intraocular lenses after posterior capsulotomy in normal dog eyes.

OBJECTIVE: To determine Nd:YAG laser energy requirements for posterior capsulotomy and intraocular lens (IOL) damage threshold for foldable acrylic IOLs as compared to traditional polymethylmethacrylate (PMMA). MATERIALS AND PROCEDURES: Four groups of five-six fresh canine cadaver eyes were used in this study. The groups included (1) unaltered eyes (2) aphakic eyes (3) eyes implanted with PMMA IOLs, and (4) eyes implanted with acrylic IOLs. Laser energy was delivered to the posterior capsule in grid fashion for 10 sites each of five levels of laser energy ranging from 0.5 mJ to 9 mJ. Number of successful capsulotomy sites was recorded based on slit-lamp observation. Sites of IOL damage were evaluated using scanning electron microscopy (SEM). Statistical analysis of number of capsulotomies and IOL defects per laser energy level was conducted among and between groups using anova with Tukey's HSD test. RESULTS: When comparing groups (a) including all energy levels (n = 25) and (b) by specific energy levels (n = 5), there was no significant difference (P < 0.05) in number of successful capsulotomy sites between IOL types. The 50% incidence threshold for successful capsulotomy was 2.74 mJ for acrylic IOLs and 2.64 mJ for PMMA IOLs. Energy-dependent damage to both types of IOL was detected for medium, high-medium, and high laser energy. Calculated 50% damage threshold was 4.9 mJ for acrylic IOL and 5.7 mJ for PMMA IOL. Damage to the IOL varied subjectively between IOL type, but there was no significant difference in number of defects caused, with the exception of high-medium energy. CONCLUSIONS: Both posterior lens capsules and IOLs were disrupted in an energy-dependent manner with minimal difference in number of capsulotomy sites or damage to the IOL between acrylic and PMMA IOLs. A therapeutic margin between capsulotomy threshold (2.6-2.7 mJ) and IOL damage threshold (4.9-5.7 mJ) was determined to reliably achieve capsulotomies with minimal IOL damage for both acrylic and PMMA IOLs in normal canine cadaver eyes.