Accuracy of a Smartphone-based Autorefractor Compared with Criterion-standard Refraction

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Public Health

Background:

• Uncorrected refractive error is a global health issue, disproportionately affecting low-income populations with limited access to eye care services and affordable eyeglasses.
• Professional eye care and corrective lenses remain inaccessible for many, highlighting the need for innovative, low-cost solutions.

Purpose of the Study:

• To assess the accuracy and usability of a novel, portable, smartphone-based autorefractor (Netra) in adult participants.
• To compare the performance of the Netra device against standard subjective refraction methods.

Main Methods:

• A cross-sectional study involved 87 adult participants, comparing the Netra autorefractor with manifest and cycloplegic refraction.
• Spherical equivalent was calculated for each refraction method, and differences were analyzed using linear mixed regression models.
• A validated questionnaire assessed the usability and ease of use of the portable autorefractor on a 100-point scale.

Main Results:

• The mean spherical equivalent measured by Netra was -2.76 D, compared to -2.49 D by manifest refraction, with a mean difference of -0.27 D.
• The mean absolute difference between Netra and subjective refraction was 0.69 D, which was statistically significant.
• Participants reported an average ease-of-use score of 75.4 ± 19.8 for the Netra device, indicating good acceptance.

Conclusions:

• The portable smartphone autorefractor demonstrated clinically significant differences from subjective refraction but showed good patient acceptance.
• The Netra device's usability suggests it could be a valuable tool for expanding eye care access, particularly in resource-limited settings.
• This technology holds potential for improving refractive error detection where trained eye care professionals are scarce.