The use of sub-Tenon's anesthesia versus a low-dose neuromuscular blockade for canine cataract surgery: A comparative study of 224 eyes.

OBJECTIVE: Assess the utility of a Sub-Tenon's anesthesia (STA) protocol to provide suitable operating conditions for canine cataract surgery and compare it to an alternative low-dose neuromuscular blockade (LD-NMB) protocol used for canine cataract surgery. PROCEDURES: Clinical study of dog eyes undergoing cataract surgery with either an STA or LD-NMB protocol. While intraoperative vitreal expansion scores and intraoperative complications were collected prospectively, globe position, intraocular pressure, return of vision, and postoperative complications were collected retrospectively. Statistical testing was used to compare results between the STA and the LD-NMB groups for the data available. RESULTS: A total of 224 eyes from 126 dogs were assessed, with 133/224 (59.4%) eyes from 99/126 (78.6%) dogs receiving STA and 91/124 (40.6%) eyes from 72/126 (57.1%) dogs receiving LD-NMB. Forty-five of these dogs (45/126; 37.7%) received STA for one eye and LD-NMB for the other eye. There was no significant change in intraocular pressure measurements following STA administration. This was not measured for the LD-NMB group. The globe achieved a central position in 110/133 (82.7%) of eyes that received STA. This was not measured for the LD-NMB group. Intraoperative vitreal expansion scores were slightly higher in STA-treated eyes compared to LD-NMB-treated eyes. The intraoperative complication rate for STA-treated eyes was higher (73/133; 54.8%) compared to NMB-treated eyes (12/91; 13.2%). The most common intraoperative complication for STA was chemosis (64/133; 48.1%), the risk of which increased with an increase in the volume of local anesthetic injected. The post-operative complication rate was higher in STA-treated eyes (28/133; 21.1%) compared to NMB-treated eyes (16/91; 17.6%). Post-operative corneal ulceration was the most common postoperative complication in STA-treated eyes (6/133; 4.5%). CONCLUSION: The STA protocol described resulted in suitable operating conditions, but more intraoperative and postoperative complications compared to the LD-NMB protocol. Despite these complications, the STA protocol did not cause a significant deleterious impact on post-operative outcomes as defined in the present study.

Posterior lens capsule rupture in non-diabetic canine cataracts: Pre-operative, intra-operative, and post-operative findings.

PURPOSE: To describe clinical features of non-diabetic canine cataracts with presumed pre-existing posterior capsule rupture (PLCR) and their surgical outcomes. METHODS: Clinical records of 497 non-diabetic canines that underwent elective cataract surgery were reviewed. Twelve canines met the inclusion criteria indicative of PLCR pre-dating surgery. RESULTS: The incidence of presumed pre-existing PLCR was 12/497 (2.4%). Cataracts included were unilateral in 10 out of 12 canines (83.3%) and bilateral in the remaining two (16.7%). Four eyes (28.6%) had clinically detectable pre-operative lens-induced uveitis. The mean age at cataract diagnosis for cases included was 6.6 years, and golden retrievers were the most common breed affected (28.6%). Phacoemulsification surgery was performed at a median time of 110 days (range 17-403 days) after presentation. Pre-existing PLCR was found intra-operatively as a large ellipse spanning the posterior capsule from equator to equator centrally in 12 eyes and peripherally in two eyes. The capsular defect in all eyes with PLCR incorporated a distinct "pseudo-capsule" preventing vitreal presentation and ruling out intraoperative surgeon rupture. Ten eyes (71.4%) received an intraocular lens implant (IOL), and 13 eyes (92.9%) maintained vision throughout a mean follow-up period of 12 months. CONCLUSION: Posterior lens capsule rupture of blunt trauma origin and associated cataract formation, as reported in humans, may also be an infrequent but distinct cause of some cases of non-diabetic canine cataracts. Medical management of phacolytic uveitis and delayed phacoemulsification surgery may be beneficial by allowing time for "pseudo-capsule" development, increasing the likelihood of IOL placement and improved visual outcomes.

Corneal diamond burr debridement for superficial non-healing corneal ulcers in cats.

OBJECTIVE: To describe the clinical outcomes and efficacy of diamond burr debridement (DBD) treatment for corneal ulceration in cats. PROCEDURE(S): Medical records of cats that received DBD at two private practices between 2015 and 2021 were retrospectively reviewed. DBD was performed using a battery-powered, handheld motorized burr and a bandage contact lens was placed in 18/21 eyes. Corneal ulceration was considered resolved if the cornea was fluorescein negative with a stable epithelial surface. Recurrence was defined as return of corneal ulceration. Descriptive statistics and a Fisher's exact test were conducted on the study population. RESULTS: Twenty-one eyes from 20 cats with superficial corneal ulcers refractory to medical treatment underwent DBD. Domestic and Burmese were the most commonly encountered breeds and the median age of affected cats was 8.83 years (range 0.5-20 years). Corneal ulceration was present for a median of 14 days prior to DBD. Healing was achieved in 81% of eyes; with four eyes failing to heal and requiring further intervention. Corneal sequestrum was reported in one case that failed to heal. Of the healed cases, three cases recurred (17.6%) at a mean of 116.3 days (range 79-135 days). Burmese were overrepresented (p < .001) in cases that failed to heal or recurred (6/7 eyes; 85.7%). The median postoperative follow-up time was 93 days (range 6-1613 days). CONCLUSIONS: Diamond burr debridement is a safe, non-invasive treatment for corneal ulceration in cats but, compared with published results, it had a lower success rate than superficial lamellar keratectomy.

Topical Ethylenediaminetetraacetic acid (EDTA) administration following corneal diamond burr keratotomy for calcareous corneal degeneration in canines.

OBJECTIVE: To evaluate the outcomes of canine patients diagnosed with corneal ulceration associated with presumed calcareous corneal degeneration (CCD) that were treated with diamond burr keratotomy (DBK) and ongoing postoperative topical 3% or 4% Ethylenediaminetetraacetic acid (EDTA). PROCEDURES: Retrospective assessment of CCD cases treated with ongoing topical EDTA following DBK between 2011 and 2020 at Veterinary Ophthalmic Referrals. Descriptive statistics of the study population were assessed, and a survival analysis was performed using R statistical software. RESULTS: A total of 51 eyes from 41 dogs were assessed, with small terrier breeds overrepresented (27/41, 65.9%). Median age of dogs at the time of diagnosis was 14.3 years (range 8-17.2 years). Following DBK, the median time to commencement of topical EDTA was 11 days (range 0-28 days). Cases were followed for a median duration of 216 days (range 42-1379 days). Corneal ulceration recurred in 7/51 (13.7%) eyes at a median duration of 80 days (range 63-156 days). The probability of recurrence of corneal ulceration associated with CCD at 12 months was 15.6% (95% CI: 4.1-25.7%). A second DBK procedure followed by ongoing topical EDTA was performed in 4/7 (57.1%) of the recurred eyes. These retreated eyes had no further recurrence recorded and a median follow-up time of 401 days (range 120-858 days). CONCLUSION: Ongoing topical EDTA following DBK is an effective adjunct treatment method for CCD with reduced rates of recurrence of CCD-associated corneal ulceration when compared to published rates of recurrence when treated with DBK alone.