Comparison of the accuracy of phone applications with Snellen chart in determining visual acuity
Keywords:Cell phone, Diagnostic techniques, Ophthalmological, Ophthalmology, Visual acuity, Snellenâ€™s chart
Objective: To correlate the visual acuity assessment as tested by smartphone application with standard Snellen visual acuity.
Methods: A total of 136 individuals were included in this analytical cross-sectional survey conducted at Shifa Foundation Community Health Center, Islamabad between January 2022 and January 2023. Individualâ€™s age â‰¥ 18 years were included. Snellenâ€™s visual acuity was assessed using a standard Snellenâ€™s visual acuity chart by the optometrist, while the Paxos checkup by DigiSight technologies was used to assess visual acuity on smart phone using one appropriately color calibrated I-phone 7 device. Both assessments were done in physically separate areas to reduce observation bias. Visual acuity from each assessment was noted in the decimal format. Data was analyzed through SPSS v 23. Frequency distribution and Pearsonâ€™s correlation was calculated to ascertain the relationship between the two study variables.
Results: A total of 88 males and 48 females were included in the study (n=136). The mean age of patients was 29.72Â±9.0 years. The mean visual acuity of right and left eyes as assessed with Snellenâ€™s chart were 0.88Â±0.2 and 0.86Â±0.22, respectively. The mean visual acuity for right and left eyes as assessed by Paxos checkup were 0.84Â±0.19 and 0.86Â±0.21, respectively. There was positive correlation was present in both eyes. The Pearsonâ€™s correlation for right eyes was r = 0.66 and significant at p = 0.001, while the correlation for left eyes was r = 0.71 and significant at p = 0.001.
Conclusions: There is a strong correlation between Snellenâ€™s visual acuity assessment and assessment of visual acuity by the smartphone application. This makes the latter a viable strategy for screening at places where taking a Snellenâ€™s chart might not be feasible.
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