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Published on: March 3, 2023
New methods for the assessment of accommodative convergence.
Ken Asakawa1, Hitoshi Ishikawa, Nobuyuki Shoji
1Department of Ophthalmology and Visual Science, Kitasato University Graduate School, Doctors Program of Medical Science, Kanagawa, Japan.
Journal of Pediatric Ophthalmology and Strabismus
|October 2, 2009
Summary
This study presents an objective method using infrared cameras to measure horizontal eye movements and accommodative convergence to accommodation (AC/A) ratios. Results show a strong positive correlation, validating the new technique for clinical use.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- Accurate measurement of binocular vision parameters is crucial for diagnosing and managing strabismus.
- Traditional methods for assessing accommodative convergence to accommodation (AC/A) ratios can be subjective.
- Objective quantification of eye movements aids in understanding visual system function.
Purpose of the Study:
- To introduce and validate a novel objective method for measuring horizontal eye movements using the first Purkinje image.
- To compare the AC/A ratio determined by this new method with the standard gradient method.
- To assess the correlation between horizontal eye movements and the stimulus AC/A ratio.
Main Methods:
- Employed infrared charge-coupled device (CCD) cameras and a TriIRIS C9000 instrument for precise measurement of horizontal eye movements (mm).
- Included 20 pediatric patients (5-9 years) with intermittent exotropia and accommodative esotropia.
- Determined stimulus AC/A ratios using the far gradient method and calculated values before and after a 3.00 diopter accommodative stimulus.
Main Results:
- The study found average horizontal eye movements of 0.5 mm/D and a stimulus AC/A ratio of 3.8 Delta/D.
- A strong positive correlation (r = 0.92) was observed between horizontal eye movements and the stimulus AC/A ratio.
- Horizontal eye movements demonstrated a direct proportionality to the AC/A ratio measured via the gradient method.
Conclusions:
- The developed infrared CCD camera-based method provides objective recordings of accommodative convergence.
- This objective measurement technique is applicable in various clinical settings for strabismus assessment.
- The findings support the utility of objective eye movement analysis in understanding AC/A relationships.
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