Abstract
Purpose :
The increased use of multifocal intraocular lenses, contact lens and reliance on smartphones has led to a demand for a system that allows refraction at various distances. We propose a refraction method using a conventional phoropter that adds an accommodative stimulus consistent with the desired refraction distance. Vision measurements were compared with and using actual distance charts.
Methods :
For emmetropes, viewing a chart for at a 5 m refraction distance is an accommodative stimulus of 0.2 D. However, for a refraction distance of 70 cm the accommodative stimulus is 1.45 D. Hence, the refraction distance is not the distance to a chart, it is considered the magnitude of the accommodative stimulus that is presented. For example, when the chart for a refraction at 5 m is presented through a −1.25 D lens, the accommodation is 1.45 D, which is equivalent to presenting the chart for a refraction distance of 70 cm. The study sample was comprised of 21 healthy adults who do not have any ophthalmologic disease other than refractive error. The mean age was 56.6±5.4 years and accommodation was 0.40±0.30 D. The Nidek TS-310 and a paper chart were used for visual acuity measurements. The TS-310 consists of a phoropter and a space saving chart, which enables refraction at 5 m or 40 cm in an installation space of approximately 50 cm in depth. The 5 m distance objective refraction (DOR) was initially measured be dialing the refraction in the phoropter. Next, a distance of approximately 70 cm was optically reproduced by adding −1.25 D to the phoropter to measure intermediate vision followed by near vision at 40 cm using the original DOR. Finally, intermediate vision at an actual distance of 70 cm was measured with a paper chart and phoropter using the DOR. The four visual acuity values were compared.
Results :
The mean LogMAR vision of the control group was −0.13±0.10 at 5 m, 0.15±0.18 at optically induced 70 cm, and 0.45±0.26 at 40 cm, and 0.09±0.16 at an actual distance of 70 cm using a paper chart. There were no significant differences between both measurements at 70 cm (P=0.649).
Conclusions :
Visual acuity measurements were equivalent using the actual distance of 70 cm and 70 cm that was optically achieved through a phoropter. The outcomes suggest that the proposed method of presenting a chart at the desired refraction distance by controlling accommodation stimulus with a phoropter is effective.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.