ObjectiveTo 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). MethodsThis 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. ResultsThe 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 threshold sensitivity, a/b-wave amplitude of F-ERG were no difference between treatment and control group at 2m, 6m and 12m after treatment (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), while the number of laser spots was no difference (P > 0.05). Conclusions577 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.
Objective To compare the therapeutic effects of 577 nm laser and 532 nm laser panretinal photocoagulation (PRP) in the treatment of non-proliferative diabetic retinopathy (NPDR). Methods This is a prospective controlled study. A total of 23 patients (41 eyes) with clinically diagnosed severe NPDR were randomly divided into two groups including 577 nm group (11 patients, 20 eyes) and the 532 nm group (12 patients, 21 eyes). 577 nm group and 532 nm group received 3 - 4 times PRP with single-point mode. The laser energy and the number of laser spots were compared, and the laser energy density was calculated. Before treatment and 1 day, 1, 3, 6 and 12 months after treatment, the changes of best corrected visual acuity (BCVA), average threshold sensitivity, a/b-wave amplitude of flash ERG (F-ERG) in the 30° - 60° visual field, and fundus fluorescein angiography (FFA) were compared between two groups. Results The response rate was 85.0% and 23.8%, respectively in the 577 nm and 532 nm group, the difference was statistically significant (χ2=15.43，P < 0.05).Compare to the pre-treatment measurement, the average threshold sensitivity, a/b wave amplitude of F-ERG and the 30° - 60°visual field were reduced at 1 day after treatment both in the 577 nm and 532 nm group, the difference were statistically significant (F=8.68, 7.57, 4.52; P < 0.05). The average threshold sensitivity (t=2.41, 3.48, 1.23), a/b wave amplitude (a wave: t=5.82, 4.45, 7.83；b wave: t=5.40, 3.23, 4.67) of F-ERG were different between 577 nm and 532 nm group at 3 , 6 and 12 months after treatment (P < 0.05). There was no retinal neovascularization and non-perfusion region in two groups at 6 months after treatment. The average laser power were (436.25±54.65) and (446.43±35.61) mW, number of laser spots were (1952.95±299.09) and (2119.05±302.69) spots, energy density were (7.60±1.30) and (7.60±3.00) mW×ms/μm2 in the 577 nm group and 532 nm group, respectively. There was no difference in average laser power (t=1.35), number of laser spots (t=2.85) and energy density (t=1.99) between two groups (P > 0.05). Conclusion Compared with the 532 nm laser, 577 nm laser treatment has better visual outcomes for NPDR patients.