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The effect of water content on the 193 nm excimer laser ablation
Author(s) -
Feltham Mark H,
Stapleton Fiona
Publication year - 2002
Publication title -
clinical and experimental ophthalmology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.3
H-Index - 74
eISSN - 1442-9071
pISSN - 1442-6404
DOI - 10.1046/j.1442-6404.2002.00496.x
Subject(s) - ablation , keratomileusis , excimer laser , water content , laser , laser ablation , materials science , ablation zone , analytical chemistry (journal) , optics , medicine , chromatography , chemistry , physics , geotechnical engineering , engineering
Background: Water content of the corneal stroma may influenceexcimer laser ablation and may therefore affect residual refractiveerror following laser in situ keratomileusis. This study reports associations between water content of hydrogel materials and laser ablation depth. Methods: Hydrated ( n = 4)and dehydrated ( n = 4) hydrogel buttons of 38%, 45%, 55% and 69% water content were ablated with the Nidek EC‐5000 ArF 193 nm excimer laser, set to deliver a ‐6.00 DS curvature. Central curvature, optical quality and water content were measured before and after ablation. Hydrated buttons were rehydrated postablation and prior to measurement, to eliminate the effect of water removal during the procedure. The ablation depth per pulse was calculated. Results: The average ablation rate for fully hydratedbuttons was 0.51 ± 0.17 µm.The ablation rate for hydrated materials (dry componentablation) reduced with increasing water content ( P < 0.001). Dry hydrogel materials (0% water content) had an average ablation rate of 0.23 ± 0.06 µm per pulse. Conclusions: For a constant laser energy output, lower watercontent materials ablated to a greater extent than higher watercontent materials. This model provides a simple way to assess theeffect of water content and dehydration on myopic laser in situ keratomileusis.