There are more than 10 million myopic persons in the United States, and over the past three years many thousands of them have undergone anterior radial keratotomy as an elective procedure in order to eliminate the need for spectacles or contact lenses. It is important to continue to study this procedure to determine if some of these persons are at risk for long term complications, and if there are ways that the surgery can be made safer and more predictable in terms of visual results. Because monkeys age faster than humans, and the 11 year old monkey is roughly equivalent to a 40 year old human, long term problems should be seen sooner in this animal model. The general goals of this application are to continue the study of the long term effect of anterior radial keratotomy and to seek ways of improving the safety and efficacy of this surgical procedure, as well as to examine histologically the effects of other forms of refractive surgery, such as epikeratophakia, on the host cornea.
Specific aims i nclude 1) following monkeys to ascertain whether the changes in corneal structure and strength after anterior radial keratotomy result in continuous and persistent endothelial damage over a minimum five year period; 2) studying the effect of various pharmacologic agents, such as collagen linkage inhibitors and antimetabolites, applied to the cornea immediately after anterior radial keratotomy, in order to inhibit, delay, or otherwise minimize scar formation so that shorter, shallower, and therefore safer incisions can be used; 3) measuring corneal thickness with the ultrasonic pachymeter and measuring corneal permeability with the fluorophotometer to evaluate endothelial function in monkey eyes after anterior radial keratotomy; 4) ascertaining the effect of postoperative corticosteroid treatment on inflammation after anterior radial keratotomy; 5) investigating morphological changes that may indicate endothelial stress, e.g., newly formed basement membrane-like material seen recently in two-year postoperative corneas; and 6) performing similar studies on monkey eyes that have undergone epikeratophakia to determine the effect of this form of refractive surgery on the long term viability of the endothelial cells. In the wound healing study, assessment of changes in corneal shape will be made by keratometric measurements, as well as by a newly developed procedure for computer analysis of corneal topographic photographs. Agents that prove useful and safe in the rabbit eye will be tested for safety and efficacy in the monkey eye, because of its anatomic and functional similarity to the human eye.
| Busin, M; Arffa, R C; McDonald, M B et al. (1988) Change in corneal curvature with elevation of intraocular pressure after radial keratotomy in the primate eye. CLAO J 14:110-2 |
| Busin, M; Yau, C W; Yamaguchi, T et al. (1986) The effect of collagen cross-linkage inhibitors on rabbit corneas after radial keratotomy. Invest Ophthalmol Vis Sci 27:1001-5 |
| Tamaki, K; Yamaguchi, T; McDonald, M B et al. (1986) Histological study of epikeratophakia tissue lenses for myopia removed from two patients. Ophthalmology 93:1502-8 |
| Yamaguchi, T; Tamaki, K; Kaufman, H E et al. (1985) Histologic study of a pair of human corneas after anterior radial keratotomy. Am J Ophthalmol 100:281-92 |
