Toric lens fitting success supported by an online fitting app
Doerte Luensmann PhD Dipl Ing (AO)*
Jill Woods, MSc MCOptom*
Marcella McParland, BSc(Hons) MCOptom^
*Centre for Ocular Research & Education (CORE) University of Waterloo, Canada
Purpose: To provide eye care professionals quick access to lens parameter availability and to make soft toric lens fitting easier, online tools are now available to calculate and suggest a first choice prescription based on the patient’s subjective refraction. How close the recommended prescription matches the dispensed lens has been investigated in this study.
Method: In clinical studies, two daily disposable toric lenses, stenfilcon A and somofilcon A, and one monthly replacement toric lens, comfilcon A (all CooperVision, Inc.), were fitted and dispensed to 54, 37 and 47 habitual lens wearers respectively, following the manufacturer’s fitting guides. The final lens prescriptions were determined by the clinician based on over-refraction and lens rotation (Final-Rx). In a secondary analysis the subjective refraction data and back vertex distance were entered in the OptiExpert™ app to determine the recommended initial trial lens (App-Rx). The prescription results from both approaches were compared by calculating the mean differences (Bland-Altman) and the percentages of matching prescriptions following predetermined allowances for sphere, cylinder and axis.
Results: The mean differences between OptiExpert™ and the clinician final prescriptions for sphere, cylinder and axis were within ±0.13DS, ±0.01DC and ±1.38 degrees, respectively. For allowance combination sphere ±0.25D, cylinder ±0.00DC, axis ±10 degrees, the lens prescriptions from both methods matched in 75-82% of eyes (82% stenfilcon A, 75% somofilcon A, 79% comfilcon A). For allowance combination of sph ±0.50D, cyl ±0.00DC, axis ±20 degrees the Final-Rx and the App-Rx matched in 86-92% of eyes (91% stenfilcon A, 92% somofilcon A, 86% comfilcon A).
Conclusions: All three toric lens types showed a predictable on-eye performance, resulting in a close agreement between the initial OptiExpert recommended prescription and the lens prescription dispensed by the clinician. The OptiExpert™ app can therefore confidently be used to assist CooperVision toric lens fitting in order to help optimize patient chair time.
1st Author Biography: After finishing an Optician apprenticeship, Doerte attended the University of Applied Sciences in Aalen, Germany to study Ophthalmic Optics. In 2000 she completed her diploma thesis at the Queensland University of Technology in Australia. After four years in private practice, Doerte conducted her PhD at the Centre for Ocular Research & Education (CORE formerly CCLR), University of Waterloo, under the supervision of Dr. Lyndon Jones. She studied the protein deposition profile on contact lenses and intraocular lenses using confocal laser scanning microscopy. Doerte is a Senior clinical scientist at CORE, conducting clinical and laboratory-based contact lens and vision research.
*Data correct at the time of submission to BCLA by NCC.