Abstract
Purpose :
To objectively study whether the goal of finding the minimum accommodation with the best visual acuity (VA) when assessing the subjective refraction (SR) is fulfilled.
Methods :
The monocular SR was assessed with a phoropter while the refractive state was dynamically measured using a custom-developed aberrometer coupled to the phoropter. The steps followed were based on the conventional procedure: 1) starting point determined as the objective refraction measured with a commercial autorefractor, 2) sphere check from +2D fogging to control accommodation followed by a reduction of the sphere in 0.25D steps until best VA, 3) astigmatic correction, 4) sphere check from +1D fogging and unfogging until the best VA with good definition was reported. Accommodation was computed as the difference of refractive state measured in the point with minimum accommodation and at each step of the SR procedure. Also, VA was recorded in each lens change during the sphere checks.
Results :
48 subjects participated in the study with a mean age ± standard deviation (SD) of 22.96±2.94 years and a mean spherical equivalent ± SD of -1.35±1.65D. In the point of minimum accommodation, the mean logMAR VA ± SD was 0.11±0.14 and this point coincided with the SR in 12.5% of the subjects. The mean difference of spherical power in the phoropter between the point of minimum accommodation and the SR ± SD was 0.40±0.36D. Further, the point in which subjects resolved best VA the first time in the SR process was analyzed. 37.5% of the subjects resolved their best VA before achieving the SR but needed a mean difference of refraction of -0.27±0.06D to be able to resolve the best VA reporting good definition, and thus achieve the SR. Only 10.4% of the subjects achieved the best VA, SR and minimum accommodation at the same point.
Conclusions :
Results show that the SR concurred at the same point as the minimum accommodation in only few of the tested subjects. In most cases the refraction in the point of minimum accommodation was more positive than SR and the VA was below the one achieved with SR, therefore most subjects were still fogged at that point. Moreover, in some subjects the best VA was resolved before reaching the SR, but the definition reported was poor. According to this, the minimum accommodation, SR and best VA coincide in very few cases which can difficult the development of new refraction technologies that rely on accommodation.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.