Purchase this article with an account.
Sarah Wierda, Shane Havens, Michael Feilmeier, Vikas Gulati, Donna Neely, Thomas W. Hejkal; Comparison of the FirstSight Refraction System With Standard Manifest Refraction In Volunteers With Myopia. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3594.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To compare the FirstSight Refraction (FSR) system, a low cost, portable refraction and spectacle dispensing system designed for use in remote areas, to standard manifest refraction (MR) in myopic subjects.
Forty-one subjects age 18 and older underwent autorefraction and uncorrected visual acuity (UCVA) testing using the ETDRS chart. A single examiner, blinded to the AR results, performed and recorded results of standard phoropter manifest refraction (MR) and best corrected visual acuity (BCVA) using trial frames. Examiners blinded to both AR and MR results performed screening and refraction using FSR. UCVA was assessed using a "Tumbling E" chart at 20 feet. An FSR Lens flipper with +0.5 D and -0.50 and +1.00 and -1.00 D lenses was used to determine if the patient has grossly myopic or hyperopic. Those subjects determined to be myopic underwent refraction with FSR lenses organized into a myopic lens bar with -0.25 D increments. FSR lens power was determined by improvement in VA. If the subject read Snellen Equivalent of 20/25 or better the corresponding lens was recorded. If the subject read 20/30 or worse, FSR astigmatism kit screening was performed. Adjusting for spherical equivalent FSR astigmatism lenses were "dialed-in" to the correct astigmatism axis to obtain BCVA. The corresponding lenses were placed in the appropriately-sized First Sight frames and BCVA using the ETDRS chart was recorded. Autorefraction, MR, and FSR results were compared using ANOVA. BCVA with MR and FSR was compared using the Wilcoxson test.
Twenty-six subjects had myopic refractive errors by MR. There was no significant difference in measured myopic spherical equivalent among the three methods; the mean (+SD) spherical equivalent was -2.45± 2.15 D by AR, -2.58 ± 1.99 D by MR, and -2.60±1.72 D by FSR ( p=0.28). TheBCVA was slightly better with MR than with FSR with a mean logMAR BCVA of -0.11 ±0.097 (95% CI of -0.14, -0.08) with MR compared to -0.057±0.14 (95% CI of -0.10, -0.01) with FSR (p=0.008).
The FirstSight system compared favorably to standard manifest refraction for both measured refractive error and BCVA. The small difference in BCVA with MR compared to FSR while statiscally significant is unlikely to be of clinical significance since both yielded excellent corrected vision. The FSR system demonstrates potential for use in remote areas with little access to equipment necessary for standard manifest refraction.
This PDF is available to Subscribers Only