Effect of diabetic retinopathy and diabetes on the intraocular straylight in pseudophakic eyes

Background: The aim of this study was to prove the relationship between the intraocular straylight level and diabetic retinopathy (DR) according to disease severity. Also, we aimed to evaluate whether diabetes mellitus (DM) per se could be a risk factor of increased intraocular straylight although we did not rely on a definite sign of DR in this study. Methods: In this prospective comparative study, ninety three eyes were enrolled and divided into four groups as follows: Group 1 (26 eyes), without DR or DM; Group 2 (25 eyes), with DM but without DR; Group 3 (21 eyes), mild to moderate non-proliferative DR; and Group 4 (21 eyes), severe non-proliferative DR. To measure the intraocular straylight in an objective manner, the C-quant straylight meter was used to preoperatively and 2 months postoperatively in all patients who underwent phacoemulsification surgery. All the patients also underwent a macular optical coherence tomography and hemoglobin A1c (HbA1c) analysis. A comparison of straylight levels adjusted by age among four groups was performed postoperatively. Results: The postoperative level of intraocular straylight was statistically significantly different among four groups (P∈<0.05). When adjusted for ages, Group 4 showed the highest straylight level when compared with Group 3 and the other two groups (P∈<0.05). Group 1 showed the lowest straylight level in comparison with Group 2 and the other two groups (P∈<0.05). There was no significant correlation between HbA1c level, duration of diabetes and postoperative straylight level. Conclusions: The level of intraocular straylight at 2 months postoperatively had a tendency to increase as the severity of DR increased. Additionally, the straylight level was higher in DM patients without DR than in patients without DM. Therefore, the severity of DR seemed to influence the intraocular straylight level. Although there is no definite sign of DR, DM per se can be a risk factor for increasing intraocular straylight. In conclusion, the level of intraocular straylight seems to be a sensitive test for detecting early retinal damage secondary to DM.