Purchase this article with an account.
M del Carmen Seres, Genis Cardona, Roser Isern, Joan Gispets; Study Of The Discrepancies Between Optimal Contact Lens Fitting And Simulated Fitting With A Computerised Videokeratography Fluorescein Evaluation Software System. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6492.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to identify the sources of discrepancy between optimal rigid gas permeable contact lens fitting (OF) and simulated fitting (SF) based on a computerised videokeratography fluorescein evaluation software system.
The Oculus Easygraph (Oculus, Inc.) contact lens fitting software was employed to determine SFs (fluorescein pattern showing alignment "on K" and edge clearance of 0.5 mm) in a sample of 28 eyes (age 40 ± 11.5 years; spherical refraction from -1.00 to -6.00 D; corneal and refractive astigmatism < -0.75 D). Fluorescein patterns, lens movement and centration were evaluated after SF, and modifications in back optic zone radius (BOZR) and total diameter (TD) were performed to achieve OF, as judged by an experienced independent practitioner. Parameter changes (PC) were scored in an open scale by allocating one point for each 1 step modification in BOZR and TD. Eyelid position, eyelid tension and blink completeness were recorded.
A median of 1 PC (range: 0 to 6) was required to achieve OF. A statistically significant correlation was encountered between PCs and eyelid position (rho = -054; p = 0.013), with smaller palpebral apertures requiring less PCs than larger ones, probably related to the lid-attachment fitting commonly associated with these cases. Lid tension and PCs displayed a weak, although not statistically significant, correlation. The number of PCs was not influenced by blink completeness.
Computerised videokeratography software systems are helpful to determine the parameters of a theoretical first contact lens, based on corneal topography and the static evaluation of fluorescein patterns. However, contact lens fitting, as a dynamic process involving multiple factors, may require one or various PCs before an optimum fit is achieved. The results from the present study suggest a direct association between eyelid position and the extent of these changes.
This PDF is available to Subscribers Only