Effect of rigid gas-permeable contact lenses on keratoconus

Objective To investigate the effect of the rigid gas permeable contact lens (RGPCL) on keratoconus in clinical practice.Methods In this retrospective study,496 eyes of 260 patients with keratoconus were fitted with RGPCLs at the optometry center of Shenyang Aier Eye Hospital between 2005 and 2009.The patients included 212 males and 48 females.Evaluations were performed on all patients.The follow-up period lasted at least 4 years to assess visual acuity,pattern matching,changes in keratometry,the apex K value,the apex thickness of the cornea and complications.Data were analyzed using a paired t test.Results All patients wearing RGPCLs obtained acceptable vision.There was a statistically significant improvement in corrected visual acuity with RGPCLs compared to spectacles (t=-30.02,P＜0.05) before and after 4 years.There was also an apex K value improvement with RGPCLs (t=3.02,P＜0.05) before and after 4 years,but not in the apex thickness of the cornea (t=1.46,P＞0.05).Four hundred thirty-two eyes (87.1％)had a three-point-touch relationship and 46 eyes (9.3％) had an apical clearance relationship.Eighteen eyes (3.6％) had an apical contact relationship.Keratometry steepness increased in only 3 eyes (0.6％)and 64 eyes (12.90％) had a flat keratometry value that was steeper than before.All patients could wear RGPCLs all day with the exception of 33 patients (6.6％) whose corneas were stained.There were no severe complications like corneal neovascularization,corneal abrasion,or keratohelcosis.Conclusion The successful fit rate of RGPCLs for keratoconus is higher.The RGPCL is safe and effective for keratoconus. Key words: Contact lenses,rigid gas-permeable ;  Keratometry ;  Keratoconus