Fitting contact lenses with adequate tear exchange and good oxygen permeability also is required to avoid oxidative damage. Keratoconic corneas have been shown to lack some of the enzyme activities necessary to process free radicals to prevent severe oxidative damage. Those abnormal wound healing processes and responses to metabolic stress in keratoconic corneas with biochemical and molecular abnormalities cause many corneal specialists to not recommend intracorneal ring insertion. It is well known that deposits accumulate over time in the lamellar channels around the rings even in normal corneas. This deposition has been postulated to be caused by metabolic stress of the keratocytes.
Poor trephination is the major cause postkeratoplasty astigmatism.
Several speakers presented clinical results with intra corneal ring insertion for keratoconus and demonstrated improvements in uncorrected and best-corrected visual acuity in some patients but variable refractive results with poor predictability and poor correlation with topography. Although myopia and asigmatism were reduced in some patients.