Isiaka Sanni Oluwasegun*

Optometry and Vision Therapy, Albasar International Foundation, Makkah Specialist Hospital Bauchi, Nigeria

*Corresponding Author: Isiaka Sanni Oluwasegun, Optometry and Vision Therapy, Albasar International Foundation, Makkah Specialist Hospital Bauchi, Nigeria.

Received: November 23, 2021; Published: December 21, 2021

Abstract

Purpose: Compare subjective refractive error and visual acuity measurement by Dyop^® acuity chart and Snellen chart.

Methods: Forty subjects aged 24.48 ± 2.01 years with visual acuity better than 6/12 were recruited at University of Benin Optometry Clinic. Refractive error and corrected visual acuity were measured by subjective refraction method with Dyop^® acuity chart and Snellen chart. The assessment sequence between the two acuity charts formats was alternated for every other patients to reduce potential refractionist bias. The duration of measurements was compared. Thibo’s notation was used to represent the refractive error findings to enhance easy analysis.

Results: There was no significant difference in terms of spherical equivalent (M), component J0 and J45 measured by Dyop^® acuity chart and Snellen chart (even with age and gender consideration) for the subjective refractive error assessments but there was disparity in the mean acuity of about 0.25 diopters with Dyop (1.17 ± 0.14 decimal units) and Snellen chart (1.60 ± 0.21 decimal units). The subjective refraction measurement with Dyop (339 ± 122 seconds) took half the duration for Snellen’s (680 ± 281 seconds).

Conclusions: Subjective refractive error measurements by a Dyop^® was comparable with Snellen chart. Dyop^® subjective refractive error assessment was twice as efficient, with a narrower variance in visual acuity measurements, compared to the subjective refraction done with Snellen charts as optotype.

Keywords: Dyop^®; Snellen Chart; Subjective Refraction; Visual Acuity

References

1. Ankland P., et al. “World blindness and visual impairment: despite many successes, the problem is growing”. Community Eye Health100 (2017): 71.
2. Naidoo KS., et al. “Global vision impairment and blindness due to uncorrected refractive error, 1990–2010”. Optometry and Visual Science3 (2016): 227-234.
3. Hytowitz A. “Dyop Test Instruction” (2021).
4. Stark S. “A comparison of Dyop color perception and dyslexia diagnosis”. Optometry and Visual Performance 4 (2020): 176-190.
5. Thibos LN., et al. “Power vectors: an application of Fourier analysis to the description and statistical analysis of refractive error”. Optometry and Visual Science 74 (1997): 367-375.
6. “Subjective comparison between Dyop and Snellen refractions”. Optometry and Visual Performance 8.4 (2020): 202-213.
7. Kaiser PK. “Prospective evaluation of visual acuity assessment: A comparison of Snellen versus ETDRS charts in clinical practice (An AOS Thesis)”. Transactions of the American Ophthalmological Society 107 (2009): 311.
8. Anstice NS and Thompson B. “The measurement of visual acuity in children: An evidence-based update”. Clinical and Experimental Optometry 1 (2014): 3-11.
9. Westheimer G. “Directional sensitivity of the retina: 75 years of Stiles–Crawford effect”. Proceedings of the Royal Society B: Biological Sciences 1653 (2008): 2777-2786.

Citation

Citation: Isiaka Sanni Oluwasegun. “Subjective Refractions Determined by Dyop® and Snellen Chart as Optotypes". Acta Scientific Ophthalmology 5.1 (2022): 43-45.

Copyright

Copyright: © 2022 Isiaka Sanni Oluwasegun. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.