| Objective:The diabetic macular edema(DME) is one the main causes of visual impairment among patients with diabetes mellitus and may develop at any stages of diabetic retinopathy. The therapeutic methods for DME mainly include laser therapy, intravitreal injection and vitrectomy, of which, laser therapy is the most classic and the most commonly used method. Although laser therapy effectively reduces the risk of visual deterioration, its fundamental mechanism causes damages to retinal structure. Conventional laser therapy causes great damage to retina, and even if macular edema disappears, the scar formed by laser may affect visual function. With the continuous development and improvement of laser technology, micro-pulse laser technology is developed in recent years, which is characterized by low damage to retina, no visible laser spot and small harm to visual function.In this study, changes in best corrected visual acuity(BCVA), central macular thickness(CMT) and mean sensitivity(MS) before and after different laser therapies are observed, and the therapeutic effect of micro-pulse laser,single-spot laser and pattern scan laser on DME is assessed comprehensively.Method:120 eyes of 60 patients who were confirmed as preproliferative diabetic retinopathy or IV phase proliferative diabetic retinopathy by fluorescein fundusangiography(FFA) and optical coherence tomography(OCT), complicated with clinically significant macular edema and had BCVA lower than 0.4 were included. These patients were randomized into the micro-pulse group, the single-spot laser group and the pattern scan laser group. 40 eyes of 20 patients in the micro-pulse group were underwent 577 nm micro-pulse laser therapy in macular region with the duty cycle of 15%; 40 eyes of 20 patients in the single-spot laser group were underwent macular laser gird photocoagulation therapy by 577 nm single-spot laser in macular region with the exposure time of 0.15 s,40 eyes 20 patients in the pattern scan laser group were underwent macular laser gird photocoagulation therapy by 577 nm pattern scan laser in macular region with the exposure time of 0.02 s. 2 weeks after the laser therapy in macular region, all patients were underwent panrentinal photocoagulation. There was no significant difference in age, BCVA, CMT and MS among the three groups before treatment. BCVA, FFA, OCT and 10° visual field across macular region of all patients were examined after treatment. Changes in BCVA, CMT and MS at 1 month, 3 months and 6 months after treatment were observed and compared. Data were input into SPSS21.0 for statistical analysis and measurement data were expressed by x±s. The mean and standard deviation of BCVA, CMT and MS before treatment and at each follow-up after treatment were calculated. With analysis of variance of repeated measurement data, changes in BCVA, CMT and MS of the three groups before and after treatment and the difference in each index between groups were compared, with P<0.05 as the standard of statistical difference.Results :1 Micro-pulse group:6 months after treatment, BCVA was improved, with statistical difference in comparison with that before treatment(P<0.05), CMT was decreased, with statistical difference in comparison with that before treatment(P<0.05), and macular edema was alleviated; MS was increased, with statistical difference in comparison with that before treatment(P<0.05).2 Single-spot laser group:6 months after treatment, BCVA was decreased, with statistical difference in comparison with that before treatment(P<0.05), CMT was decreased, with statistical difference in comparison with that before treatment(P<0.05), and macular edema was alleviated; MS was decreased, with statistical difference in comparison with that before treatment(P<0.05).3 Pattern scan laser group:6 months after treatment, BCVA was decreased, with statistical difference in comparison with that before treatment(P<0.05), CMT was decreased, with statistical difference in comparison with that before treatment(P<0.05), and macular edema was alleviated; MS was decreased, with statistical difference in comparison with that before treatment(P<0.05).4 Comparison among groups: at 6 months of follow-up, BCVA and CMT of the three groups showed no statistical difference(P>0.05), while MS of micro-pulse group was improved and single-spot laser group,pattern scan laser group were decreased with statistical difference(P<0.05).Conclusion:1 Micro-pulse laser therapy on DME may not only alleviate macular edema and enhance BCVA, but also increase MS and improve visual function.2 Single-spot laser and pattern scan laser therapies may effectively alleviate macular edema, but they may cause damage to vision, reduce MS and affect visual function.3 Micro-pulse laser,single-spot laser and pattern scan laser therapies on DME can effectively reduce CMT and alleviate macular edema, with no significant difference. |
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