The effect of the timing of the cessation of contact lens use on the results of biometry

Abstract

Background: Current guidelines vary regarding when to remove contact lenses prior to performing biometry, and there is no clear evidence behind these guidelines. This study aimed to determine the effect of soft contact lens wear on biometric measurements by examining the change in predicted lens power for emmetropia at several time points following removal of soft contact lenses. Methods: A prospective, controlled study of healthy soft contact lens wearers. Biometry was performed immediately after removing contact lenses and then after 2, 4 and 7 days of no contact lens use. Healthy non-contact lens wearers were used as controls. All measurements were taken with the Zeiss IOLMaster. Results: In all, 14 subjects and 13 controls were recruited. There was no significant difference in age or gender between groups. Eight of the fourteen subjects wore daily disposable CLs, two wore 2-weekly and four wore monthly soft CLs. Measurements from controls and contact lens-wearing subjects showed similar degrees of variation over time. The within-subject SD in predicted intraocular lens (IOL) power for emmetropia for contact lens wearers was 0.20 D (95% CI 0.16-0.25 D) compared to 0.18 D (95% CI 0.12-0.26 D) for controls. Conclusions: There is a significant variation in UK practice regarding advice on the timing of cessation of contact lens wear prior to having biometry performed. Our study suggests that it is likely that soft contact lens wearers are currently being advised to remove their contact lenses for an unnecessarily long period of time prior to having biometry performed.