Acanthamoeba keratitis and contact lens disinfecting solutions.

OBJECTIVES: To report cases of culture-proved Acanthamoeba keratitis in Greece over a 10-year period and to evaluate the effectiveness of the commonly used commercial contact lens disinfecting systems in clinical cases of Acanthamoeba keratitis. MATERIAL AND METHODS: During the years 1994-2004, 45 contact lens wearers and 3 non-contact lens wearers presenting with symptoms and signs of keratitis underwent corneal sampling. The scrapings obtained were inoculated directly onto appropriate culture media for bacteria, fungi and Acanthamoeba. All proved positive for Acanthamoeba. The contact lenses and contact lens disinfecting solutions (16 one-step 3% hydrogen peroxide and 3 multipurpose solutions) of 19/45 patients with culture-proven Acanthamoeba keratitis were cultured for bacteria, fungi and Acanthamoeba. RESULTS: Acanthamoeba was isolated from contact lenses and contact lens disinfecting solutions in all 19 cases of Acanthamoeba keratitis studied. CONCLUSIONS: The main risk factor for corneal infection in contact lens wearers is the use of contact lens disinfecting systems ineffective at killing Acanthamoeba cysts and trophozoites, as well as bacteria and fungi. Improvement or development of new contact lens disinfecting systems by manufacturers is needed to prevent Acanthamoeba keratitis.

Corneal topography for intraocular lens power calculations.

BACKGROUND: In patients undergoing cataract extraction with PC IOL insertion, pre-op and post-op corneal power measurement is necessary to calculate induced astigmatism. In cases with irregular corneal astigmatism, measurements with traditional keratometry is inaccurate. We report the use of video keratography in three cases that required keratometry readings in order to calculate IOL power. These cases were characterized by irregular or incomplete keratometer mires, so quantitative descriptors derived from computer-assisted corneal topography (TMS-1) were used instead. CONCLUSION: The standard keratometer is useless in cases in which the mires appear irregular or incomplete. In such cases, computer-assisted corneal topography can be used successfully. Recently, a new corneal topography index has been developed, the average corneal power, which is a measure of the average corneal power within the entrance pupil. We are currently evaluating the use of average corneal power to assist in the calculation of IOL powers.