Related Experiment Video
Updated: Nov 14, 2025
05:36
Subjective Refraction Test Using a Smartphone for Vision Screening
Published on: October 18, 2024
1.3K
Instant vision assessment device for measuring refraction in low vision
1School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China.
Clinical & Experimental Optometry
|March 10, 2021
Summary
The Instant Vision Assessment Device (IVAD) offers a practical and valid method for refracting low vision patients. This device accurately measures refractive error, improving vision assessment for those with reduced visual acuity.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- Low vision patients require specialized refraction techniques due to reduced visual acuity and increased blur tolerance.
- The Instant Vision Assessment Device (IVAD) is a novel stenopaeic slit refraction system integrated into a binocular telescopic optometer.
- This study aimed to validate the efficacy of IVAD for refractive measurements in individuals with low vision.
Purpose of the Study:
- To assess the accuracy and reliability of the Instant Vision Assessment Device (IVAD) in measuring refractive errors in low vision patients.
- To compare IVAD refraction measurements with traditional subjective refraction (SR) in both normal and low vision subjects.
- To evaluate the visual acuities achieved with IVAD and SR in the low vision cohort.
Main Methods:
- Refractive error was measured using IVAD and SR in 35 normal subjects (ages 9-69) and 20 low vision subjects (ages 60-90).
- Paired Student t-tests and Bland-Altman analyses were employed to determine statistical significance and agreement between the two measurement methods.
- Visual acuities obtained with IVAD and SR were compared in the low vision group.
Main Results:
- No statistically significant differences were found in spherical equivalent refraction (M) between IVAD and SR for both normal and low vision subjects.
- While a statistically significant difference in astigmatism (J0) was noted in normal subjects, it was within acceptable clinical limits.
- Over 80% of IVAD refraction components (M, J0, J45) demonstrated agreement within ±0.50 D compared to SR measurements.
- Mean visual acuities in the low vision group were comparable between IVAD and SR (0.52 ± 0.32 logMAR vs. 0.53 ± 0.32 logMAR).
Conclusions:
- The Instant Vision Assessment Device (IVAD) is a practical and validated tool for refractive assessment in low vision patients.
- IVAD provides accurate and reliable refractive measurements, comparable to subjective refraction.
- The device holds potential for improving the efficiency and effectiveness of low vision examinations.
