Quantification of Vitreous Opacity by a Newly Developed Method Based on Analysis of Interframe Differences in Slitlamp Movies

Abstract

Purpose :
Some patients who receive an intraocular lens (IOL) experience reduced visual function such as that known as waxy vision. We hypothesized that one cause of this change might be vitreous opacity (VO) due to vitreous floaters (VF). Given that VF are often evaluated subjectively, we set out to develop and evaluate a method for the objective quantification of VF.

Methods : A total of 83 eyes with an implanted IOL was enrolled in the study. We focused on the membrane-shaped VO in the anterior vitreous cavity, with see-through structures, but with clearly defined shapes. According to severity of the VO, the eyes were classified into three groups, on the basis of whether VO was mild (n = 25), moderate (n = 28), or severe (n = 31), by ophthalmologists who were unaware of the experimental condition. Movies focused on the anterior vitreous were obtained with a slitlamp microscope and were subjected to interframe difference analysis developed in-house for quantitation of VF. Fifteen frames were selected from each movie, and differences between successive frames were analyzed. The sum of the differences was determined to provide an estimate of VO.

Results : The mean ± SD values of VO determined by our interframe difference method for eyes in the mild, moderate, or severe groups were 1.600 ± 1.360, 3.000 ± 1.039, and 3.310 ± 1.533, respectively. The values for eyes with moderate or severe VF were significantly greater than that for eyes with mild VF (P < 0.01, by Mann-Whitney U test), whereas those for moderate or severe VF were not significantly different from each other. The value of VO was not correlated with visual acuity.

Conclusions :
Our newly developed interframe difference method shows potential for quantification of VF and may be a better alternative than clinical grading of VO severity. It should prove helpful for examination of the relation between VF and visual deficits after cataract surgery.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.