Corneal tissue ablation depth and the Munnerlyn formula.

摘要: Abstract Purpose To determine whether the error in ablation depth produced by approximations inherent Munnerlyn formula are clinically significant when estimating residual corneal stromal for evaluation before refractive surgery. Setting Department of Ophthalmology, University Texas Medical Branch, Galveston, Texas, USA. Methods Using identical geometric assumptions, exact was calculated and compared to approximate predicted formula. An adjustment factor then derived large optical zones corrections. Results The is always larger than Munnerlyn’s Analysis found varied as fourth power zone linearly with correction. initial radius had little effect on difference. could be reasonably approximated adding an Conclusions In patients zones, it may preferable calculate tissue using Alternately, can used added.