Panretinal photocoagulation (PRP) and macular photocoagulation (MPC) are the gold standard treatments for proliferative diabetic retinopathy (DR) and diabetic macular edema. With the development of equipment and technology advancement, photocoagulation has been gradually applied in many Eye Centers all over China. However, there are still several problems such as no standardized guideline and undesirable therapeutic effects. In this article we will summarize the indications and techniques of photocoagulation, and when and how to apply drug treatments for retinal diseases; aim at improving the criterion and clinical effects of photocoagulation.
Objective Toinvestigate the influence of photocoagulation on macular function and morphous in patients with diabetic retinopathy (DR).Methods Forty eyes of thirty patients with severe nonproliferative diabetic retinopathy (NPDR) were examined by multifocal electroretinogram (mfERG) and optical coherence tomography (OCT) before and 2,7, and 14 days after photocoagulation. The results were statistically analyzed by using analysis of variance and t test; the changes of macular function and macular fovea thickness were detected and observed.Results P1 response densities of ring 1,3,and 5 were 131.79plusmn;50.92，37.50plusmn;17.27，24.07plusmn;11.49，respectively,2 days after photocoagulation; and were 212.96plusmn;53.75，46.70plusmn;15.89，and 30.91plusmn;10.78, respectively, before photocoagulation. The densities before and after photocoagulation differed much（t=7.910, 2.174, 2.205; Plt;0.05）. N1 response density of ring 4 was（60.39plusmn;20.69） and the prephotocoagulation corresponding response density was （107.11plusmn;44.63）; the difference was significant（t=5.375，Plt;0.01）. The latency of P1 of ring 4 was（41.83plusmn;3.41），which had significant statistically difference（t=-2.770，Plt;0.05) with that before photocoagulation（39.52plusmn;2.64); there was no significant changes in the latency of N1 (Pgt;0.05). The most significant changes of P1 and N1 response densities occurred in the central macular 5deg; area. Seven days after photocoagulation, the response density of P1 and N1 in the central macular 5deg; area seemed to be recoverd to some extend and increased to （179.70plusmn;47.10）and (81.11plusmn;34.18) respectively until 14 days after photocoagulation, which was still much lower than that before the photocoagulation（t=3.840, 2.746; P＜0.05）; the response densities of other areas had no significant differences (P＞0.05). Seven days after photocoagulation,the latency of P1 in ring 4 was delayed to（41.78plusmn;3.57）, which had significant difference（t=-3.144，P＜0.01）with that before the photocoagulation（39.52plusmn;2.64) ; but there was no significant difference between 14 days after photocoagulation and prephotocoagulation (t=-1.809，P＞0.05). The latency of N1 in ring 1 was（20.67plusmn;3.85）at seven days after photocoagulation, It had no significant difference (t=-1.171,P＞0.05) with that before the phtocoaguation（18.78plusmn;3.29）. Before and 2 days after photocoagulation, the macular fovea thickness were（224.42plusmn;122.88）and（274.85plusmn;108.20）respectively, and the difference was statistically significant（t=-2.420，P＜0.05）. Forteen days after photocoagulation，the macular fovea thickness was（236.29plusmn;70.45），It had no significant difference with that before the photocoagulation（t=-0.578，P＞0.05）. Before and seven days after photocoagulation, P1 response density had obvious negative correlation with corresponding macular fovea thickness（r=-0.755，Plt;0.01; r=-0.594，Plt;0.05）. Conclusions After photocoagulation in patients with DR，the macular function decreased in a certain degree，and the relationship of macular retinal function and macular morphology changes was close; combination of mfERG and OCT can evaluate macular function and macular morphology structure comprehensively and objectively.
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.