Effect of contact lens use on corneal thickness measurements
We were pleased to read the article by Braun and coauthors1 contributing additional data on the effect of contact lens wear on central corneal thickness measurement. The underlying mechanisms affecting corneal thickness in contact lens wearers when fully elucidated will have clinical implications in the screening of patients as candidates for tissue subtractive refractive surgery. Additional clinical implications could include avoiding acceleration of any ectasia in keratoconus patients and in monitoring intraocular pressure in contact-lens-wearing glaucoma patients if the cornea is thinning.
Our earlier study2 analyzed 250 eyes in consecutive patients considering laser vision correction and did not find a statistically significant reduction in soft contact lens wearers but a significant 37 μm reduction in corneal thickness in rigid contact lens wearers. We also observed a 76 μm interocular reduction in a patient who wore a rigid contact lens in 1 eye. Although corneal hypoxia and contact lens wear has been extensively studied, we would welcome additional prospective studies including the correlation of epithelial defects as tear components may potentially trigger loss of keratocytes and production of corneal collagen.3
Elliott H Myrowitz OD
Terrence P O'Brien MD
Baltimore, MD, USA
1. Braun DA, Anderson Penno EE. Effect of contact lens wear on central corneal thickness measurements. J Cataract Refract Surg 2003; 29:1319-1322
2. Myrowitz EH, Melia M, O'Brien TP. The relationship between long-term contact lens wear and corneal thickness. CLAO J 2002; 28:217-220
© 2004 by Lippincott Williams & Wilkins, Inc.
3. Zhao J, Nagasaki T, Maurice DM. Role of tears in keratocyte loss after epithelial removal in mouse cornea. Invest Ophthalmol Vis Sci 2001; 42:17