Abstract
Purpose :
To assess changes on optical coherence tomography (OCT-A) in diabetic macular edema (DME) treated with subthreshold micropulse yellow laser (SMPL) over six months.
Methods :
This is a retrospective, consecutive case series including 27 eyes(27 patients) with DME treated with SMPL. Inclusion criteria were:good quality swept source OCT-A and OCT images (DRI OCT Triton plus,Topcon Medical Systems Europe, Milano, Italy), fundus color photo and best corrected visual acuity(BCVA) recorded on the same day (before treatment, at 3 and 6 months). Following parameters were evaluated on OCT-A maps (3mmx3mm area) in the superficial(SCP) and deep capillary plexuses (DCP): the area of foveal avascular zone, number of microaneurysms (micro), presence of: capillary loss and capillary network irregularities and the area of the cysts on en-face OCT-A images. On SD-OCT: retina thickness on OCT map;on linear B-scan at 0°: number of hyperreflective retinal spots(HRS) counted in the area of 3000 µm centered on the fovea. All measurements were performed by 2 masked graders, independently. Statistical analyses took into account DM duration and HbA1c values as covariates.
Results :
All patients had DM type 2(mean age, 66.2+12.6 years; duration of DM, 12.2+7.8 years, HbA1c 7.6+0.8%). Mean number of laser spots was 435.1+126.9. Mean BCVA at baseline was 76.8+9.6 ETDRS letters with no significant increase over 6 months follow-up. There was no significant change in any evaluated parameter in the SCP, except for the area of the cysts that was absent in 33.3% of the eyes at six months (McNemar’s test, p=0.04). In DCP, there was a significant reduction in the number of micro at 6 months(8.4+3.7 at baseline, to 4.2+2.7, p=0.0002) and in the area of the cysts(638.4+586.5 μm2 at baseline to 387.6+320.1μm2, p=0.02). Mean number of HRS progressively decreased over time, without reaching statistical significance. Higher number of micro(p=0.03) and smaller area of the cysts in the DCP(p=0.04) at baseline was associated with greater reduction in HRS at 6 months. Greater area of the cysts at DCP at baseline was associated with greater retina thickness at 6 months.
Conclusions :
Subthreshold micropulse laser induces more pronounced changes in DCP then in SCP in DME. These changes occured not before six months after SMPL treatment. Evaluation of specific parameters in DCP may help in determining HRS and retinal thickness response.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.