Biodegradable tube implants in experimental glaucoma surgery in the rabbit.

Although ocular drainage implants are manufactured from biocombatible materials to reduce foreign-body reaction, the formation of excessive scar tissue around the implant is a common cause for implant failure. In this study, the suitability of poly(D, L-lactide-co-glycolide) copolymer, impregnated with an antiproliferative agent retinoic acid, was evaluated as a material for biodegradable tubular implants, as well as the duration and magnitude of the intraocular pressure reduction obtained with the prototype implant. Subconjunctivally placed retinoid-impregnated polymer particles caused a milder inflammatory reaction than plain polymer, and the layer of connective tissue around the material was thinner after the follow-up period of 60 d. In the anterior chamber, the inflammatory response elicited by the material was milder than subconjunctivally. The plain polymer caused a transiently stronger reaction than the retinoid-impregnated polymer, but after 60 d no difference was evident between the two materials. In all operated eyes with the tubular implant, the intraocular pressure was statistically significantly lower (p<0.05) than in control eyes for 9 wk after the operation. The intraocular pressure of the eyes with the retinoid-impregnated implant was statistically significantly lower (p<0.05) than in eyes with a plain polymer implant for up to 7 wk post-operatively. However, the use of retinoid did not prolong the effective functioning time of the implants.

The effect of heparin-surface-modification on scar-tissue formation around a subconjunctival polymethylmethacrylate implant in the rabbit.

PURPOSE: Excessive scar tissue formation around ocular drainage implants is a common cause for implant failure. The purpose of this study was to evaluate the effect of heparin-surface-modification of a subconjunctival polymethylmethacrylate implant on scar-tissue formation in the rabbit eye. METHODS: Plain and heparin-surface-modified polymethylmethacrylate implants were implanted subconjunctivally in the eyes of 13 rabbits in two groups consisting of 8 and 5 animals. In the latter group the implants were in contact with aqueous humour through a fistula into the anterior chamber. RESULTS: Both unmodified and heparin-surface-modified polymethylmethacrylate implants were well tolerated. In histological sections studied by both light microscopy and transmission electron microscopy, heparin-surface-modification of polymethylmethacrylate implants seemed to diminish the formation of scar tissue around the subconjunctival implants. CONCLUSION: Heparin-surface-modification of polymethylmethacrylate implants could provide one way to affect the formation of excessive fibrous tissue around ocular drainage implants.

The effect of intraoperative injection of hyaluronan under a one-piece glaucoma filtration implant in the rabbit eye.

The effect of a single intraoperative injection of hyaluronan on intraocular pressure (IOP) and postsurgical tissue healing was evaluated on 18 rabbits with an aqueous drainage implant. During the follow-up period IOP was recorded and analysed. Furthermore, inflammatory reaction and appearance of the fibrous tissue around the implants were studied in histological sections. In both the hyaluronan and control groups the operation lowered the average IOP statistically significantly for the whole follow-up period when compared with preoperative values. From days 7 to 60 the mean IOP values of the hyaluronan injected eyes stayed at a lower level than in the control eyes, but with no statistical difference between the 2 groups. The connective tissue layer around the implants appeared less dense during the first 17 postoperative days in the sodium-hyaluronate group; in addition, the inflammatory cell reaction showed a tendency to remain acute longer.

A one-piece ocular drainage implant for glaucoma surgery: a preliminary report.

A one-piece silicone filtration implant for glaucoma surgery was evaluated in 18 normotensive rabbits. During the follow-up period of 60 days the function of the implant and the effect of the implant on intraocular pressure (IOP) and local reaction in operated eyes were examined. Mean IOP in operated eyes during the whole follow-up period stayed in a level that was statistically significantly (p < 0.001) lower than the preoperative starting value. Despite of a slight inflammatory reaction in the immediate postoperative period the implants were well tolerated. No marked foreign body reaction were noted around the implants in histological sections. In 3 eyes the implants had to be removed due to complications caused by surgical technique.

The effect of sodium-hyaluronate on scar tissue formation under a subconjunctival silicone implant in the rabbit.

The effect of sodium-hyaluronate on scar tissue formation under a subconjunctival silicone implant was examined in twenty rabbits. During the follow-up period histological sections for evaluation of local reaction and thickness of fibrous tissue were made at day 7, 17, 30 and 60. Although no statistically significant difference could be shown the thickness of scar tissue under the implant in hyaluronate injected eyes was greater than in control eyes during the first seventeen postoperative days, after which the difference started to diminish. Also the inflammatory response in hyaluronate injected eyes in the early postoperative period was more noticeable than in control eyes.

Mycotic keratitis in a horse caused by Aspergillus fumigatus. The first reported case in Finland.

The first identified Finnish case of equine mycotic keratitis caused by Aspergillus fumigatus is described. The clinical picture, the sampling method, the macro- and micromorphology of the causative fungus and the therapy applied are reported in detail. Therapy with natamycin (Pimafucin 2.5% eyedrops. Gist-Brocades) was successful.