Combined resection and recession of a single rectus muscle for the treatment of incomitant strabismus.

BACKGROUND: The treatment of incomitant strabismus is challenging. Traditional approaches include the use of asymmetric bilateral surgery and the fadenoperation (posterior fixation suture). We report our experience with a different approach: combined resection and recession of a single rectus muscle. METHODS: The charts of 12 patients who underwent resection of a single rectus muscle with an equal or greater amount of recession of the same muscle were identified. In 5 patients, the procedure was performed using the adjustable suture technique, and the adjustment was performed later the same day (Group 1). In the remaining 7 patients, permanent sutures were placed at the time of surgery (Group 2). The procedure was performed for horizontal and vertical gaze incomitance, dissociated horizontal deviation, and distance-near disparity. RESULTS: Four of the 5 patients in Group 1 showed stable, long-term correction of their incomitance, both in primary gaze and in gaze in the direction of the muscle operated on. The results for patients in Group 2 showed stable, long-term correction of incomitance in 3 patients; however, these patients also had slight overcorrections in the direction of gaze opposite to the muscle operated on. An additional patient in Group 2 had a shift of her distance-near disparity, shifting from relatively exotropic to relatively esotropic disparity postoperatively. All patients in Group 2 showed at least some decrease in the amount of measured incomitance. We did not encounter complications such as muscle slippage or loss, scleral perforation, or late overcorrection in the field of gaze of the operated muscle. CONCLUSIONS: The technique of combined resection and recession of a single rectus muscle shows promise in the treatment of incomitant strabismus. It offers the advantages of posterior fixation combined with the greater technical ease of a standard hangback recession. The muscle may also be placed on an adjustable suture, allowing for postoperative adjustment in selected patients.

Transscleral diode laser cyclophotocoagulation for refractory pediatric glaucomas.

PURPOSE: To evaluate the success of contact transscleral cyclophotocoagulation (TDC) in patients with refractory pediatric glaucomas. METHODS: Twenty-six eyes of 20 patients with therapy-resistant pediatric glaucomas were included in this retrospective study. Subgroup analysis was performed for patients 10 or younger and patients older than 10 at time of first TDC procedure. Diode laser cyclophotocoagulation was applied using a fiber optic G-probe. Follow up until time of failure or for a minimum of 6 months was obtained for all procedures in all eyes. Failure was defined as intraocular pressure (IOP) greater than 21 mm Hg, repeat of TDC due to clinically inadequate IOP control, progression to another procedure, or serious complication. RESULTS: Baseline mean pretreatment IOP was 34.2 +/- 10.4 mm Hg (range, 15 to 62 mm Hg). Ten of 26 eyes (38%) were successful 6 months after initial TDC. A mean decrease in IOP of 10.3 +/- 14.7 mm Hg was noted after the first procedure (P < 0.05). Eighteen eyes (70%) were retreated at least once. The mean decrease in IOP for all patients after all procedures was 12.9 +/- 13.4 mm Hg (P < 0.001). This represents a mean percent decrease in IOP of 33.2 +/- 6.9%. The overall success rate was 50%, including retreated patients. The younger and older subgroups did not differ with regard to overall success, time to failure, or retreatment rats. One patient suffered a retinal detachment. Visual loss was noted in 4 of 22 eyes with reliable visual acuity measurements. CONCLUSION: TDC is an effective means of decreasing IOP in some patients with refractory pediatric glaucomas. Although the retreatment rate is high, the procedure generally is well tolerated with few complications.

Cat model for intraocular pressure reduction after transscleral Nd:YAG cyclophotocoagulation.

Transscleral neodymium:yttrium-aluminum-garnet (Nd:YAG) laser cyclophotocoagulation (TSNYC) is used to lower intraocular pressure (IOP) in glaucoma patients refractory to conventional medical and surgical therapy. Our study investigates the ability of TSNYC to lower IOP in normal cats. One eye of 13 cats was treated with non-contact TSNYC. Mean pretreatment IOP was 25 mm Hg (vs. 25.3 mm Hg in contralateral control eyes). Eyes received 80 laser applications over 360 degrees delivered at least 3 mm posterior to the limbus with maximum power (8 to 9 joules) and maximum retrofocus (3.6 mm). Eyes were retreated if IOP was not reduced below baseline after 2 weeks. By 4 weeks, IOP was decreased in all treated eyes by a mean of 29.2% and was maintained as long as 20 weeks (mean decrease 14.8%). IOP in 10 eyes was lowered after a single treatment session. Of these, 2 eyes had IOP spikes > 10 mm Hg prior to IOP reduction. Three cats required retreatment to maintain IOP reduction. All eyes developed transient (< 4 weeks) postoperative uveitis and 3 eyes developed rubeosis iridis which resolved with topical corticosteroids. Histologic examination (6 weeks post-treatment) showed focal disruption of the pigment epithelium and to a lesser degree the nonpigmented epithelium at the base of the ciliary body and in the valleys of the pars ciliaris. The epithelium at the apices of the ciliary processes appeared intact. Vascular engorgement was variably present. This study demonstrates that TSNYC lowers IOP in cats. This animal model will be useful for investigating mechanism(s) responsible for TSNYC-induced IOP reduction.

Effects of topical k-strophanthin on aqueous humor and corneal dynamics.

PURPOSE: Sodium-potassium-activated adenosine triphosphatase (Na/K ATPase) is present in the ciliary epithelium, where it serves a regulatory role in fluid transport and the production of aqueous humor. The present study investigates the ability of topical k-strophanthin, a water-soluble mixture of glycosides, to lower intraocular pressure. METHODS: K-strophanthin was topically administered to one eye and vehicle to the fellow control eye of rabbits, cats, and human volunteers. RESULTS: Single drop 0.01 M k-strophanthin delivery lowered pressure in rabbits and cats to a maximal decrease of 5-6 mm Hg 3-4 h after drug administration. Higher drug concentrations irritated the eye, whereas lower concentrations had no effect. Pressure reduction in rabbits was associated with decreased aqueous humor formation, and no change in outflow facility and episcleral venous pressure. Drug delivery in humans had a minimal intraocular pressure effect. Slit-lamp and histologic examination of rabbit eyes after chronic drug administration was normal. However, single drop administration of 0.01 M drug was found to significantly increase corneal thickness, the aqueous to cornea fluorescein transfer coefficient, and the corneal endothelial permeability coefficient. CONCLUSIONS: Topical k-strophanthin lowers pressure via reduction of aqueous production and most probably by inhibition of the enzyme Na/K ATPase in the ciliary epithelium. The drug's effect on corneal function probably relates to a similar block of this enzyme in the epithelial layers of the cornea, which limits the usefulness of k-strophanthin and other previously studied Na/K ATPase inhibitors as an ocular hypotensive agent.