Effect of vitreous opacities on straylight measurements

PURPOSE: To evaluate the effect of vitreous floaters on intraocular straylight.

METHODS: Records of bilaterally phakic patients with unilateral complaint of floaters as the main symptom were identified from an electronic database. Patients who underwent straylight measurements on both affected and unaffected eyes using a C-Quant straylight meter were selected. Data were collected on age, sex, visual acuity, straylight measurements, and optical coherence tomography. The unaffected eye served as a control.

RESULTS: Fifteen cases were included (7 women and 8 men; mean age, 54.3 years; age range, 24-71 years). Visual acuity was not correlated with the complaint of floaters. Average straylight value in eyes with floaters was 1.426 log(s) (±0.23 SD) with a median value of 1.52 log(s). The mean value for fellow eyes was 1.275 (±0.23 SD) with a median of 1.25 log(s). The differences between both groups using a Wilcoxon matched-pair signed-rank test was statistically significant at P = 0.0009. On optical coherence tomography, most patients had a confirmed or probable posterior vitreous detachment. However, in four patients, a posterior vitreous detachment was absent in the affected eyes. Vitreous floaters were inconsistently imaged by optical coherence tomography, with only a few patients presenting appreciable condensations close to the retinal surface. These were present in both affected and unaffected eyes.

CONCLUSION: Intraocular straylight is significantly increased in eyes affected by floaters. No correlation was seen with vision or optical coherence tomography appearance. Straylight is an independent objective measure of visual perception that seems to be closely correlated to complaints expressed by patients experiencing floaters.