Abstract
Purpose: :
To evaluate the feasibility of using semi–automated analysis of digital fundus images to quantify the effects of laser photocoagulation on retinal vessel diameter in retinopathy of prematurity (ROP).
Methods: :
7 patients who developed threshold ROP (stage 3 plus, ICROP definition) and were treated with laser photocoagulation were included in this study. These patients were selected from a larger study involving digital imaging of 54 infants at risk for developing ROP that had birth weights less than 1250 grams and gestational ages less than 32 weeks. Digital fundus images of the disk and posterior pole were captured during routine ROP exams in awake infants using a NIDEK NM200D fundus camera. Photographs were repeated one or two weeks after laser photocoagulation. Using VesselMap semi–automated software (IMEDOS), retinal vascular diameters were measured from the digital images in a masked fashion. The same segment of four temporal vessels was measured across study dates. Nonparametric methods were used to assess the change in vessel diameter after laser treatment. Results are shown in arbitrary units (AU).
Results: :
High quality images were obtained from all 7 patients before undergoing laser photocoagulation treatment. 4 patients had high quality digital images 1 week after laser treatment and 3 patients had photos 2 weeks after laser treatment. We observed a significant reduction in the average diameter of the largest retinal vein of –21% ± 15% (± 1 SD) following laser treatment (Wilcoxon rank sum test, p = 0.02). There was a trend towards a decrease in the average diameter of the largest retinal artery of –16% +/– 20%, but this reduction did not reach statistical significance.
Conclusions: :
Our results show a statistically significant decrease in the diameter of the largest retinal vein following laser retinal photocoagulation for retinopathy of prematurity. These preliminary data show the feasibility of quantifying changes in retinal vessels in ROP using digital images taken in awake infants during a routine clinical examination. Further studies are needed to investigate whether quantitative vessel diameter measurements may help predict clinical outcomes, and may be useful in diagnostic or therapeutic investigations of ROP.
Keywords: retinopathy of prematurity • imaging/image analysis: clinical