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Lens density measurements by two independent psychophysical techniques.
Anirbaan Mukherjee1, Richard A Bone1
1Department of Physics, Florida International University, 11200 SW 8th Street, Miami, 33199 FL USA.
Eye and Vision (London, England)
|September 14, 2016
Summary
Lens optical density (LOD) measurements using Mapcat sf™ under photopic conditions showed reasonable correlation with scotopic measurements. While not statistically significant, individual differences highlight the need for further investigation into factors affecting lens equivalent age (LEA) assessment.
Area of Science:
- Ophthalmology
- Vision Science
- Optometry
Background:
- Cataract is a primary cause of vision impairment due to increased lens optical density (LOD).
- Accurate LOD measurement techniques are crucial for detecting incipient nuclear cataract.
- Mapcat sf™ measures LOD under photopic conditions, converting it to lens equivalent age (LEA), but cone ratio variability may affect accuracy.
Purpose of the Study:
- To assess the agreement between LEA measurements obtained under photopic and scotopic conditions.
- To identify factors contributing to discrepancies in LEA measurements.
- To evaluate the reliability of Mapcat sf™ for routine lens density assessment.
Main Methods:
- Lens equivalent age (LEA) was measured using Mapcat sf™ in 25 subjects.
- LEA data from photopic conditions were compared with measurements taken under absolute scotopic threshold conditions.
Main Results:
- Mean scotopic LEA was 2.7 years higher than photopic LEA, a difference that was not statistically significant.
- Photopic and scotopic LEA measurements demonstrated a reasonable correlation (r²=0.59, p<0.0001).
- Significant individual LEA differences were observed in six subjects, with cone ratios and pupil diameter variability identified as potential contributing factors.
Conclusions:
- The absolute threshold technique for lens density measurement is likely impractical for routine use due to long adaptation times.
- Mapcat sf™ offers a rapid and straightforward method for lens density measurement, suitable for optometric and ophthalmic practice.
