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Inducement and Evaluation of a Murine Model of Experimental Myopia
Published on: January 22, 2019
Optical compensation for night myopia based on dark focus and CA/C ratio
J C Kotulak1, S E Morse, J C Rabin
1Evans US Army Community Hospital, Fort Carson, Colorado, USA.
Investigative Ophthalmology & Visual Science
|July 1, 1995
Summary
Individual differences in dark focus and convergence accommodation to convergence (CA/C) ratio can optimize night myopia correction. Prescribing lenses based on these factors improves visual performance in low CA/C individuals and high CA/C individuals.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- Night myopia, a condition affecting visual acuity in low light, presents challenges for optical correction.
- Individual variations in ocular responses, such as dark focus and accommodation, are known to influence refractive error.
- Understanding these individual differences is crucial for personalized vision correction strategies.
Purpose of the Study:
- To investigate if dark focus and the convergence accommodation to convergence (CA/C) ratio can guide the prescription of optimal optical corrections for night myopia.
- To determine the relationship between these individual factors and the required lens power for best visual acuity under dim lighting conditions.
Main Methods:
- Visual acuity and contrast sensitivity were measured across various lens powers and luminance levels to determine optimal correction for night myopia.
- Dark focus was assessed using an infrared optometer.
- Convergence accommodation to convergence (CA/C) ratio was measured using an infrared optometer and an eyetracker in young subjects (mean age 25.4 years).
Main Results:
- Optimal lens power for night myopia showed a significant correlation with dark focus, irrespective of the CA/C ratio.
- A steeper regression slope between lens power and dark focus was observed in subjects with lower CA/C ratios (<0.4 D/MA) compared to those with higher ratios (>0.4 D/MA).
- Mean optimal lens power and dark focus differed between low and high CA/C groups, indicating distinct refractive responses.
Conclusions:
- Intersubject variability in dark focus and CA/C ratio are significant factors in optimizing visual performance for night myopia.
- For individuals with low CA/C ratios, prescribing a lens power approximating their full dark focus yielded the best visual outcomes.
- For individuals with high CA/C ratios, a lens power of half their dark focus was found to be optimal.
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