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[How accurate is video refraction measurement in infants in comparison with skiascopy? How much do the values change
1Klinik für Augenkrankheiten, Kantonsspital, St. Gallen.
Insights
Isotropic photorefraction is suitable for infant refractive screening, but has limitations. It shows 1-2 dpt errors for spherical refraction and 2-3 dpt for astigmatism, necessitating supplementary methods for precise spectacle prescription.
Area of Science:
- Ophthalmology
- Pediatric Optometry
- Vision Science
Background:
- Isotropic photorefraction is a screening tool for infant vision.
- This study evaluates its accuracy and limitations as a measuring instrument.
Purpose of the Study:
- To analyze the limitations of isotropic photorefraction in infants.
- To compare photorefraction results with streak retinoscopy and repeat photorefraction.
Main Methods:
- 215 infants (5-12 months) underwent cycloplegic examination.
- Results were compared to streak retinoscopy and repeat photorefraction after 6 months.
Main Results:
- Spherical refraction: Mean difference of 0.70 dpt vs. retinoscopy (SD 0.67 dpt).
- Astigmatism: Mean difference of 0.73 dpt vs. retinoscopy (SD 0.90 dpt), with up to 9 dpt variation in some cases.
- Repeat measurements showed small myopic shifts and changes in astigmatism.
Conclusions:
- Photorefraction exhibited 1-2 dpt errors for spherical and 2-3 dpt for astigmatic refraction.
- Significant aberrations occurred in 5% of infants.
- Photorefraction is suitable for screening high refractive errors but requires supplementary methods for precise prescription.
Background:
Isotropic photorefraction (Atkinson et al., 1981) is a method used to screen the refraction in infants. The aim of this study is to analyze its limitations as a measuring instrument.
Materials And Methods:
215 children aged between 5 and 12 months were examined in cycloplegia. The results were subsequently compared (1) to the results of streak retinoscopy also performed at the same time and (2) to photorefraction performed a second time, 6 months later (with 145 children).
Results:
Spherical refraction: The mean spherical values differed by 0.70 dpt through photorefraction methods, compared to retinoscopy. The standard deviation (SD) was 0.67 dpt. The values of the photorefraction differed therefore in 95% of the children within a range of 2.7 dpt (or +/- 2 SD). Compared to the second photorefractive measurement 6 months later, the average refraction showed a small myopic shift (-0.45 dpt). Astigmatism: The errors of measurement were more pronounced here. Extreme differences of up to 9 dpt were found in single cases. The mean difference, compared to retinoscopy, was 0.73 dpt. The standard deviation (SD) was 0.90 dpt. In 95% of the children, the values of photo-refraction differed therefore by a range of 3.6 dpt (or +/- 2 SD). Compared to the second photorefractive measurement 6 months later, the average refraction showed a mean change of 0.73 dpt.
Conclusions:
Our photorefractive measurements showed errors in the range of 1-2 dpt for the spherical refraction, and in the range of 2-3 dpt for astigmatism. In 5% of the children examined, even greater aberrations were found. As long as the aim of photorefraction is restricted to disclosing high refractive errors, this method is judged suitable for the refractive screening of infants. For more precise refraction, and for the prescription of spectacles, we believe that is should be supplemented by a second examination technique, such as retinoscopy or automated refractometry.