To assess changes on optical coherence tomography (OCT) angiography in diabetic macular edema (DME) treated with subthreshold micropulse yellow laser (SMPL) over a period of 6 months.
Thirty-five eyes (35 consecutive patients) with treatment-naive DME prospectively underwent (at baseline, 3 and 6 months) best-corrected visual acuity, swept-source OCT angiography/OCT, and fundus autofluorescence. Following parameters were evaluated on OCT angiography in the superficial capillary plexus (SCP) and deep capillary plexus (DCP): the area of foveal avascular zone, number of microaneurysms (MA), area of cysts, and presence of capillary network alterations. Microaneurysm change was also evaluated in 15 fellow eyes, not needing treatment over 6 months. Vessel and perfusion densities were evaluated in the SCP, DCP, and choriocapillaris, with image J. Retina thickness, number of hyperreflective retinal spots, and external limiting membrane integrity were evaluated on OCT. All measurements were performed by two masked graders, independently.
All patients had diabetes mellitus Type 2 (mean age, 69.4 ± 10.9 years; duration of diabetes mellitus, 15.7 ± 8.7 years; and HbA1c 7.7 ± 1.2%). Mean best-corrected visual acuity at baseline was 69.7 ± 12.0 letters ETDRS, 72.7 ± 10.7 at 3 months (gain 3.1 ± 4.3, P = 0.0049) and 74.3 ± 9.5 at 6 months (gain 4.6 ± 7.2, P < 0.0001). Foveal avascular zone area decreased in the DCP at 6 months (P = 0.01). Area of cysts decreased in the SCP at 3 months and 6 months (P = 0.038; P = 0.049), and in the DCP at 6 months (P = 0.0071). Number of MA decreased at 6 months in the SCP (P = 0.0007) and at 3 months and 6 months in the DCP (P = 0.048; P < 0.0001) in treated eyes. No significant change in number of MA was found in nontreated eyes. There was no statistically significant change in any other OCT angiography/OCT parameter.
Subthreshold micropulse yellow laser induces more pronounced changes in the DCP than in the SCP in DME. These changes occurred as early as 3 months after treatment. The evaluation of specific parameters in the DCP may help in determining treatment response.
Subthreshold micropulse laser determines more pronounced changes in the deep capillary plexus than in the superficial capillary plexus, as early as 3 months after treatment, in diabetic macular edema. Optical coherence tomography angiography may help in the evaluation of specific parameters in the deep capillary plexus that may be useful in determining the response to treatment.
*Eye Unit, University Hospital Maggiore della Carita', Novara, Italy;
†Medical Physics, University Hospital Maggiore della Carita', Novara, Italy;
‡Department of Clinical Science and Community Health, University of Milan, Milan, Italy;
§Eye Clinic, San Giuseppe Hospital, Milan, Italy;
¶Eye Clinic, University of Milan, San Paolo Hospital, Milan, Italy; and
**Department of Health Science, University East Piedmont “A. Avogadro,” Novara, Italy.
Reprint requests: Stela Vujosevic, MD, PhD, FEBO, Eye Unit, University Hospital Maggiore della Carita', Corso Mazzini 18, 28100 Novara, Italy; e-mail: firstname.lastname@example.org
None of the authors has any financial/conflicting interests to disclose.