Myopic hydrogel keratophakia. Improvements in lens design.
In order for a refractive surgical procedure to be generally accepted, it must give a predictable result as well as generate a suitable optical surface. Previously, in a non-human primate model, we showed that hydrogel intracorneal lenses could flatten the cornea and thereby be used as a potential treatment for myopia. Over 20 D of central corneal flattening was observed in some cases. It was evident that the major corneal flattening occurred only in a very small area covered by the first corneascopic ring and that this area was irregular in that an elliptical reflection was generally obtained. We herein present the results of myopic hydrogel lens design modification. By enlarging the size of the lens and optical zone, the central corneal flattening became more regular as judged by corneascopic analysis. With the most recent lens designs, animals with high-minus implants showed circular corneascopic images with an average of 10.0 D of central flattening. This observation of corneal flattening was confirmed with autorefractor readings (average, -8.5 D) and keratometric readings (average, -9.0 D). These results are compared with earlier lens implants 5.5 mm in diameter where flattening was documented by reading the central corneascopic ring and could not be confirmed with either keratometric or autorefractor data. We feel these preliminary attempts at lens design modification have significantly enhanced the potential for future clinical application of this technique.
Werblin
T P
TP
Department of Ophthalmology, University of North Carolina, Chapel Hill.
Patel
A S
AS
D000818:Animals; D001251:Astigmatism / Q000209:etiology; D003315:Cornea / Q000601:surgery*; D004867:Equipment Design; D007910:Lenses, Intraocular / Q000009:adverse effects; D008253:Macaca mulatta; D009216:Myopia / Q000601:surgery*