Comparison of the efficacy of multi-point or single-point mode of 577 nm laser in the treatment of diabetic retinopathy

Abstract

Objective To compare the therapeutic effects of 577 nm laser panretinal photocoagulation (PRP) between one time multi-point scanning mode and multiple time single-point mode in the treatment of eyes with non-proliferative diabetic retinopathy (NPDR). Methods This is a prospective controlled study from August 2013 to February 2014. A total of 29 patients (46 eyes) with clinically diagnosed severe NPDR were randomly divided into two groups including the treatment group (12 patients, 22 eyes) and the control group (17 patients, 224 eyes). The treatment group received one time PRP of multi-point scanning mode, and the control group received 3 - 4 times of PRP with single-point mode. In order to evaluate its efficacy, the best corrected visual acuity was measured before treatment, and 1 day, 1, 2, 6 and 12 months after treatment. The average threshold sensitivity, a/b-wave amplitude of flash ERG (F-ERG) in the 30 ° - 60 ° visual field, and fundus fluorescein angiography (FFA) of the change were also compared between the 2 groups. The laser energy and the number of laser spots were compared, and the laser energy density was calculated. Results The response rate was 86.4% and 79.2%, respectively in the treatment and control group, the difference was not statistically significant (χ2= 0.414, P>0.05). Compare to the pre-treatment measurement, the average threshold sensitivity, a/b-wave amplitude of F-ERG in the 30 ° - 60 ° visual field were reduced at 1 day after treatment both in treatment and control group, the differences were statistically significant (P 0.05). The average laser power, number of laser spots and energy density were (537.50 ± 64.69) mW and (339.09 ± 132.09) mW, (1934.32 ± 426.38) points and (2061.42 ± 375.49) points, (0.35±0.12) mW o ms/μm2 and (1.95 ±0.86) mW·ms/μm2 in the treatment group and the control group, respectively. The average laser power and energy density was statistically different between the 2 groups (P 0.05). Conclusions 577 nm multi-point scanning laser can complete the PRP at one time, and achieve the same therapeutic outcomes with the single-point mode which need several times to complete the PRP in the eyes with severe NPDR, and have lower energy density, and thus relative minor function damage. Key words: Diabetic Retinopathy/therapy; Laser coagulation/methods; Laser coagulation/utilization