ABSTRACT
OBJECTIVE: To determine regional and zonal variation in sulfation patterns of chondroitin sulfate in normal equine corneal stroma. SAMPLE POPULATION: 22 normal eyes from 11 horses. PROCEDURE: Corneas were collected within 24 hours of death from equine necropsy specimens. After papain-chondroitinase digestion of corneal tissue, disaccharides deltaDi4S and deltaDi6S were quantified by use of capillary zone electrophoresis in the superficial, middle, and deep zones of central and peripheral regions of the cornea. RESULTS: For the 2 regions combined, deltaDi6S/deltaDi4S values were significantly lower in the deep and middle zones, compared with that of the superficial zone. In the central region, deep and middle zones had significantly lower deltaDi6S/deltaDi4S values than the superficial zone did. In the peripheral region, the deep zone had significantly lower deltaDi6S/deltaDi4S values, compared with superficial and middle zones. In the deep zone, the peripheral region had significantly lower deltaDi6S/deltaDi4S values than the central region did. CONCLUSIONS AND CLINICAL RELEVANCE: Distribution of deltaDi6S/deltaDi4S values follows a gradient across the healthy equine cornea, being smallest in the deep and middle zones of the central region and the deep zone of the peripheral region. Regional and zonal differences in the distribution of stromal deltaDi6S and deltaDi4S may influence the role of glycosaminoglycans in health, disease, and wound repair of the equine cornea.
Subject(s)
Chondroitin Sulfates/chemistry , Corneal Stroma/chemistry , Horses/metabolism , Animals , Reference ValuesABSTRACT
Contact neodymium:yttrium aluminum garnet (Nd:YAG) laser transscleral cyclophotocoagulation (TSCP) was performed on 23 eyes of 16 horses for treatment of glaucoma. The mean highest preoperative IOP was 51 +/- 17 mmHg. Follow-up evaluation was available for 19 eyes 1 day after surgery, 14 eyes from 1 to 2 weeks, 16 eyes from 4 to 6 weeks, 9 eyes from 12 to 16 weeks, and 10 eyes greater than 20 weeks after laser treatment. The mean intraocular pressure (IOP) the day following surgery was 34 +/- 13 mmHg. The mean IOP for each follow-up period was: one to two weeks postoperative, 23 +/- 9 mmHg; four to six weeks, 24 +/- 7 mmHg; 12-16 weeks, 28 +/- 10 mmHg; and >/= 20 weeks, 22 +/- 9 mmHg. IOP measurements were significantly different from pretreatment values for all follow-up intervals except for weeks 12-16 (P < 0.05). Treatment success was defined as maintenance of IOP < 30 mmHg. Treatment success was achieved in 93%, 88%, 78%, and 70% of the treated eyes at the 1-2 weeks, 4-6 weeks, 12-16 weeks, and the >/= 20 weeks re-evaluation, respectively. No significant difference was found between the number of eyes visual at presentation (52.2%) and visual at 20 weeks (60%). The most common laser complications were conjunctival hyperemia (21.7%) and corneal ulcers (13.0%). Results of this study indicate that Nd:YAG TSCP is an effective method of controlling IOP and preserving vision in horses with glaucoma. An effective Nd:YAG laser protocol for TSCP in the equine glaucomatous eye is a power setting of 11 W, duration of 0.4 s, applied 5 mm posterior to the limbus at 60 sites, resulting in a total energy dose of 264 J.
