The efficacy and safety of 577 nm subthreshold micropulse laser on diabetic macular edema / 中华眼底病杂志

ABSTRACT

Objective To evaluate the clinical efficacy and safety of 577 nm subthreshold micropulse laser on diabetic macular edema (DME).Methods Retrospective case series study.A total of 30 patients (35 eyes) with center-involving DME were enrolled in this study.All the patients received the examinations of best corrected visual acuity (BCVA),fundus colorized photography,fluorescein fundus angiography (FFA) and optical coherence tomography (OCT).BCVA was measured by Early Treatment Diabetic Retinopathy Study charts.The average retinal thickness (ART),total macular volume (TMV) and the retinal thickness (RT) and macular volume (MV) of 9 ETDRS domains were measured by the Japanese Topcon 3D-OCT 2000 instrument.The mean BCVA was 62.4± 10.5 letters.The mean ART was 327.3± 41.2 μm.The mean TMV was 9.24 ± 1.17 mm3.All patients were treated with 577 nm subthreshold micropulse laser treatment.Subthreshold micropulse laser were performed in the micropulse mode,using a 200 μm spot diameter,a 0.2 s duration with 5％ duty cycle and its treatment energy was 6-7 times of threshold energy.Three months after treatment,re-treatment was performed on patients with incomplete absorption of macular edema.The treatment was the same as before.The BCVA,ART,TMV and the RT and MV of each ETDRS domain were compared and analyzed before and after treatment.The possible complications of micropulse laser treatment were also observed and the safety was evaluated.Results The difference of BCVA were statistically significant in month 3 and month 6 (t=-5.58,-7.24;P＜0.05),but not in month 1 (t=-1.82,P＞0.05).The average CRT (t=4.11,4.17,5.96),CMV (t=3.92,4.05,5.80) significantly decreased in 1,3 and 6 months after treatment,the difference was statistically significant (P＜0.05).At sixth months,the average retinal thickness (t=3.53,5.07,5.02,4.87,4.94,3.48,4.03,3.17,3.73) and retinal volume (t=3.54,5.16,4.99,4.91,5.05,3.47,4.08,3.10,3.70) of the 9 ETDRS subdomains significantly decreased,and the difference was statistically significant (P＜0.05).There was no visible laser spots,changes in the outer retina and complications of neovascularization and subretinal fibrosis in the fundus of all patients.Conclusion 577 nm subthreshold micropulse laser can reduce the CMT,CMV and improve the BCVA of DME patients with high security.