Self‐assessment of refractive errors using a simple optical approach

Abstract

BackgroundThis explorative study investigated procedures for the self‐assessment of spherocylindrical refractive errors.MethodsEighteen participants with a mean age of 34.0 ± 8.8 years were enrolled. Adjustable Alvarez lenses were mounted in a rotatable ring holder and two procedures were tested for the self‐adjustment: (1) rotation of the lens in three meridians: 0°, 60° and 120° and (2) rotation of the optotypes in the same meridians. Starting from maximum positive power, the participants were required to decrease the power of the Alvarez lens until the optotypes (0.0 logMAR) appeared to be clear the first time. Best‐corrected visual acuity (BVA) was measured using a psychophysical staircase procedure. Bland–Altmann analysis was carried out in order to calculate the limits of agreement between the self‐refraction method and the standard subjective refraction.ResultsUsing procedure 1, 77 per cent of the subjects achieved a VA ≥ 0.1 logMAR (6/7.5) and the same was true for 88 per cent of the subjects using procedure 2. Using procedure 1, a significantly worse BVA was found, when compared to subjective refraction (ΔVA = −0.15 logMAR, F3,140 = 7.11, p = 0.046, median test). Analysis of variance (ANOVA) analysis showed a significant influence of the refraction method on the oblique astigmatism component J45 but not for the spherical equivalent M and the straight astigmatism component J0 (M: F3,140 = 0.532, p = 0.661; J0: F3,140 = 0.056, p = 0.983; J45: F3,140 = 13.97, p < 0.001; ANOVA). The limits of agreement for the spherical equivalent error M were ± 1.10 D and ± 1.20 D and for the astigmatic components J0 ± 0.78 D and ± 0.59 D and for J45 ± 0.62 D and ± 0.54 D, for procedure 1 and procedure 2, respectively.ConclusionsFixed adjustable Alvarez lenses and rotatable stimuli can provide a fast and precise self‐assessment method to measure the spherocylindrical error of the eye.

A Comparison Between Refraction From an Adaptive Optics Visual Simulator and Clinical Refractions

“…Analogously to autorefraction, for wavefront sensor refractometers there are many validation studies 7 , 12 , 14 , 37 , 38 and the 95% limits of agreement ranged from ±0.56 D (interval of 1.12 D) 14 to ±1.04 D (interval of 2.08 D). 12 Finally, automated subjective refraction is not as popular as objective refraction systems; however, there exist a few studies, 25 , 27 , 29 , 36 , 38 , 39 each with a completely different automated algorithm, that found 95% limits of agreement between ±0.52 D (interval of 1.04 D) 38 to ±1.20 D (interval of 2.40 D). 39 Our results (and others) indicate that automated refraction techniques with devices such as the VAO are promising areas for applying artificial intelligence and algorithms for improving prediction of visual outcomes.…”

Beyond traditional subjective refraction

“…Leube et al [21] proposed a quick subjective selfrefraction procedure based on adjusting the shift of pair of Alvarez lenses until the refractive error is compensated. As in other self-refraction techniques (see later), the results show poor agreement with respect to traditional subjective refraction (LOAs: AE 1.20D).…”

The Direct Subjective Refraction: Unsupervised measurements of the subjective refraction using defocus waves

“…The EYER method [4] combines a wavefront autorefractor and a phoropter to, based on the answers of the subjects to specific questions, change the lenses of a phoropter and obtain the refractive error subjectively. Leube et al [32] tested an unsupervised self-refraction procedure based on the shift of a pair of Alvarez lenses to compensate for the spherical refractive error. Rotation of the lenses also allows the compensation of astigmatism.…”