SURFACE-MORPHOLOGY FOLLOWING PHOTOREFRACTIVE KERATECTOMY

To examine the effects of surface dehydration on corneal surface morph ology before and after photorefractive keratectomy, corneas of fresh p orcine eyes were deepithelialized and then immediately fixed or treate d according to one of six protocols (four eyes per protocol): dehydrat ed under the illumination of an operating microscope; dehydrated and t hen rehydrated with topically applied balanced salt solution; photoref ractive keratectomy; photorefractive keratectomy followed by surface d ehydration; or photorefractive keratectomy followed by dehydration and subsequent rehydration. Surface smoothness (S) was measured with an i mage analysis system. The surfaces of the unablated corneas were smoot h (S = 0.992 +/- 0.002), and dehydration did not significantly (P = .7 ) influence the morphology. After ablation, dehydration resulted in ap parent fragmentation of the superficial lamellae, with consequent roug hening of the surface (P = .0001). Rehydration was only partially succ essful in reducing surface irregularity. We conclude that corneal dehy dration during and following photorefractive keratectomy roughens the corneal surface and should be carefully avoided.