Sub-Tenon's anesthesia for canine cataract surgery

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.

The clinical outcomes of 33 canine eyes following the novel sulcus fixation technique of an injectable acrylic lens through a 3-mm corneal incision

PURPOSE

This retrospective study introduces and evaluates transscleral fixation using a horizontal mattress suture of a conventional injectable acrylic intraocular lens (IOL) inserted through a 3-mm corneal incision in dogs.

MATERIALS AND METHODS

This technique was applied to four groups: lens subluxation (group SL, n = 15), anterior or posterior lens luxation (group APLL, n = 9), lens capsule tear or rupture (group LCTR, n = 7), and dislocation of the lens capsule containing an IOL (group IOLD, n = 4).

RESULTS

Patients were followed up for an average of 366.7 days (range: 94-830 days) after the surgery. Each IOL was well-centered and the overall visual success rate was 74.3% (26/35). Retinal detachment (4/35) was the most common cause of blindness, followed by glaucoma (3/35), hyphema of unknown etiology (1/35), and severe uveitis accompanied by deep corneal ulcer (1/35).

CONCLUSION

This technique enables sulcus fixation of an IOL, inserted through a 3-mm corneal incision, which is less traumatic than conventional techniques, without the need for specifically designed IOL for sulcus fixation. In this series, this technique enabled to contribute to restore emmetropic vision in dogs.

Effects of Cisatracurium in Sevoflurane and Propofol Requirements in Dog-Undergoing-Mastectomy Surgery

The purpose of the present study was to test whether the addition of cisatracurium in combination with propofol and sevoflurane would result in a change in doses of used anesthetic drugs. Ten dogs (Group A) undergoing elective unilateral mastectomy surgery were included in the study. To induce and maintain anesthesia, subjects received propofol and sevoflurane at varying doses; analgesia was performed with remifentanil. After three months, the same subjects (Group B) underwent contralateral mastectomy and received the same anesthetic protocol with the addition of cisatracurium at a dosage of 0.2 mg/kg−1. The following parameters were monitored during anesthesia: heart rate, systolic blood pressure, end-tidal CO2, oxygen saturation, halogenate requirement, and rectal temperature at baseline (T0), induction (T1), 5 (T5), 10 (T10), 15 (T15), 20 (T20), 25 (T25), 30 (T30), and 35 (T35) time points. In Group A, halogenate requirement was reduced at all the time points other than T1 (p < 0.001); in Group B, the percentage of halogenate requirement was already reduced at T1 and remained constant during the experimental period, showing no significant intragroup differences. The dose requirements of sevoflurane and propofol varied significantly between the two groups, with significantly lower dosages in the Group B (the cisatracurium-treated group). Moreover, patients treated with cisatracurium showed a stable anesthetic plan. The nondepolarizing-muscle-relaxant cisatracurium besylate could be considered a useful adjunct to anesthetic protocols.

Comparison of image quality of corneal and retinal optical coherence tomography using sedation and general anesthesia protocols with or without retrobulbar anesthesia in horses

OBJECTIVE

To compare image quality and acquisition time of corneal and retinal spectral domain optical coherence tomography (SD-OCT) under 3 different sedation-anesthesia conditions in horses.

ANIMALS

6 middle-aged geldings free of ocular disease.

PROCEDURES

1 randomly selected eye of each horse was evaluated via SD-OCT under the following 3 conditions: standing sedation without retrobulbar anesthetic block (RB), standing sedation with RB, and general anesthesia with RB. Five regions of interest were evaluated in the cornea (axial and 12, 3, 6, and 9 o'clock positions) and fundus (optic nerve head). Three diagnostic scans of predetermined quality were obtained per anatomical region. Image acquisition times and total scans per site were recorded. Corneal and retinal SD-OCT image quality was graded on a subjective scale from 0 (nondiagnostic) to 4 (excellent).

RESULTS

Mean values for the standing sedation without RB, standing sedation with RB, and general anesthesia conditions were 24, 23, and 17, respectively, for total cornea scan attempts; 23, 19, and 19 for total retina-scan attempts; 14.6, 13.2, and 9.2 minutes for total cornea scan time; 19.1, 9.2, and 13.0 for total retina scan time; 2.0, 2.3, and 2.5 for cornea grade; and 2.7, 2.9, and 2.5 for retina grade.

CONCLUSIONS AND CLINICAL RELEVANCE

The RB facilitated globe akinesia and improved the percentage of scans in frame and region of interest accuracy for retinal imaging via OCT in horses. Retrobulbar blocks improved clinical image acquisition while minimizing motion artifact.