Subthreshold Micropulse Laser Photocoagulation Research Articles

Efficacy of subthreshold micropulse laser photocoagulation therapy versus anti-vascular endothelial growth factor therapy for refractory macular edema secondary to non-ischemic branch retinal vein occlusion.

To assess the efficacy of subthreshold micropulse laser photocoagulation (SMLP) therapy versus anti-vascular endothelial growth factor (anti-VEGF) therapy in patients with refractory macular edema (ME) secondary to non-ischemic branch retinal vein occlusion (BRVO). This single-center, prospective, nonrandomized, case-control trial involved patients with refractory ME that responded poorly to three or more initial anti-VEGF injections. The patients were examined and divided into two groups according to their chosen treatment: the intravitreal ranibizumab (IVR) group and the SMLP group. Both groups were followed up monthly for 12 months. Therapeutic efficacy and safety were assessed throughout the follow-up period. The IVR group comprised 49 eyes, and the SMLP group comprised 45 eyes. The improvements in the optical coherence tomography findings and visual acuity were comparable between the two groups at the final follow-up. The total number of injections was significantly lower in the SMLP than IVR group. No serious adverse events occurred during the study period. SMLP therapy is better for patients with central macular thickness (CMT) of ≤400 μm. For patients with CMT of >400 μm, we advise continuation of anti-VEGF agents to reduce ME followed by application of SMLP therapy when CMT has decreased to ≤400 μm.

New approaches in the detection and management of diabetic retinopathy in the near future

Diabetes mellitus (DM), a group of metabolic diseases characterized by hyperglycemia, is a major public health problem worldwide. In recent years, the incidence and prevalence of DM has been increasing as a global epidemic. Diabetic retinopathy (DR) is the most common complication of DM and remains the major cause of preventable blindness among working-age people in most developed countries and it has a significant socioeconomic impact and source of morbidity. DR, which has long been recognized as a microvascular disease, has been demonstrated by laboratory and clinical evidence that inflammation and retinal neurodegeneration may also contribute to diabetic retinal damage in the early stages of DR. New diagnostic and treatment modalities in DR management is promising. Further elucidation of the underlying molecular mechanisms may provide new medical approaches for the development of novel therapeutic modalities. Nowadays, novel diagnostic devices such as ultrawide field fundus fluorescein angiography, optic coherence tomography angiography and adaptive optics retinal imaging have improved the detection of DR earlier, faster and more accurately. Subthreshold micropulse laser and other laser photocoagulation applications may be an alternative to conventional retinal photocoagulation with lower complications for DR treatment. In recent years, artificial intelligence, machine learning, and deep learning based diagnosis and treatment applications are developing. In addition, in recent years, unmanned automated-based diagnostic and treatment methods and newly developed intravitreal drugs and implants can offer more diagnostic and treatment options with promising results. This review provides an overview of novel diagnostic and treatment approaches for preventing the progression of diabetic retinopathy.

Comparative Efficacy of Subthreshold Micropulse Laser Photocoagulation versus Conventional Laser Photocoagulation for Diabetic Macular Edema: A Meta-Analysis

Background: Laser photocoagulation is an effective procedure for the treatment of diabetic macular edema (DME). However, the beneficial effects of conventional laser photocoagulation (CLP) are accompanied by the destruction of retinal photoreceptors. Therefore, subthreshold micropulse laser photocoagulation (SMLP) was proposed for DME. Objectives: This meta-analysis study was performed to evaluate the efficacy and safety of SMLP compared with CLP for the management of DME. Methods: The PubMed, Embase, Web of Science, Cochrane, SinoMed, ClinicalTrials.gov, Wanfang, and China National Knowledge Infrastructure (CNKI) databases, published until Dec 2021, were searched to identify studies evaluating the clinical outcomes of SMLP for DME. Results: Eight randomized controlled trials were selected for this meta-analysis involving a total of 546 eyes (275 eyes in SMLP group and 271 eyes in CLP group). SMLP of different wavelengths (577 nm and 810 nm) and duty cycles (5% and 15%) was applied. The pooled outcomes showed that SMLP group, especially 577 nm and 810 nm 15% duty cycle parameter settings, had a statistically significant higher efficacy than CLP group in terms of BCVA (MD = −0.02, 95% CI: −0.03 to −0.01, p < 0.01; MD = −0.09, 95% CI: −0.09 to −0.09, p < 0.01) and showed more significant advantages than CLP group in resolving macular edema assessed by reduction of CMT (MD = −32.87, 95% CI: −37.61 to −28.13, p < 0.01; MD = −8.01, 95% CI: −9.06 to −6.96, p < 0.01), whereas the efficacy of 577 nm and 810 nm 5% duty cycle SMLP subgroups remained numerically superior to CLP group, but nonsignificantly (p > 0.05). In the field of CS, SMLP group (no matter parameter settings) resulted in better preservation of CS compared to CLP group (MD = 1.96, 95% CI: 1.47–2.46, p < 0.01). Conclusions: Compared with CLP, SMLP may get superior efficacy and safety on improvement of BCVA, reduction of CMT, and preservation of CS. In clinical, SMLP can be considered as a safe and effective therapy in the management of DME.

Subthreshold micropulse laser photocoagulation versus half-dose photodynamic therapy for acute central serous chorioretinopathy

PurposeTo compare the efficacy and safety of subthreshold micropulse (STMP) laser photocoagulation and half-dose photodynamic therapy (PDT) in the treatment of acute central serous chorioretinopathy (CSC).MethodsA total of 39 acute CSC patients were included. 18 patients were treated with STMP laser and 21 patients were treated with half-dose PDT. The main outcome measures were best-corrected visual acuity (BCVA) according to Early Treatment Diabetic Retinopathy Study (ETDRS) chart, the proportion of eyes with complete resolution of subretinal fluid, the number of treatments, and the retinal sensitivity by microperimetry during the 12-month study period.ResultsThe mean number of treatments during the 12-month period was 1.6 in STMP group and 1.3 in half-dose PDT group, respectively (P = 0.174). The proportion of eyes with complete resolution of subretinal fluid was 83.3% in STMP group compared with 90.5% in half-dose PDT group at 12-month (P = 0.647). The mean BCVA at 12-month after treatment was 75.28 ± 12.58 for STMP group and 76.62 ± 11.57 for half-dose PDT group, respectively (P = 0.731). No statistically significant difference was found in the mean retinal sensitivity between the two groups during the 12 months follow-up (P = 0.701 at 3 months; P = 0.725 at 6 months; P = 0.695 at 12 months).ConclusionsSubthreshold micropulse Laser Photocoagulation is as effective as half-dose PDT for acute CSC, while minimizing the damage effect on retinal.

Analysis of Clinical and Functional Results of the Developed Technology of Combined Laser Treatment of Initial Stages of Idiopathic Epiretinal Membrane

Aim. To analyze the clinical and functional results of the combined technology for laser treatment of patients with the initial stages of idiopathic epiretinal membrane.Methods. This study included 3 groups of patients: the main group (32 patients) after the combined laser technology (subthreshold “grid” laser photocoagulation (LP) and subthreshold micropulse LP); control group (30 patients) which did not receive any treatment; comparison group (30 patients) after subthreshold “grid” LP. The assessment uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), central retinal thickness (CRT) and central retinal sensitivity (CRS) was performed. The follow-up period was 5 years.Results. In the control group a slow decrease of UCVA, BCVA, CRS (p &lt; 0.05) and an increasing CRT (p &lt; 0.05) were observed. In the main group maximal UCVA, BCVA, CRS (p &lt; 0.05) were marked from 3 to 6 months after laser treatment and there was a gradual decrease in the CRT indices. In the comparison group, a short-term positive effect was achieved up to 3 months with an increase of UCVA, BCVA, CRS (p &lt; 0.05). 12 months post op there was an increase in CRT with a decrease of UCVA, BCVA, and CRS until the end of study.Conclusion. The technology of combined laser treatment showed high efficiency in control and comparison groups, with stabilization/increase of UCVA, BCVA, CRS and stabilization/improvement of the morphological parameters of the retina – the decrease of CRT with ERM involution.

The effect of conbercept combined with 577 nm subthreshold micropulse laser photocoagulation on diabetic macular edema

Objective To observe the effect of conbercept combined with 577 nm subthreshold micropulse laser photocoagulation on diabetic macular edema (DME). Methods A prospective randomized controlled clinical study. From June 2016 to June 2017, 68 eyes of 68 patients with DME diagnosed in Central Theater Command General Hospital were enrolled in the study. The patients were randomly assigned to two different treatment groups: 36 eyes (36 patients) in the conbercept combined with 577 nm subthreshold micropulse lase group (combined treatment group) and 32 eyes (32 patients) in conbercept group (drug treatment group). All patients received three initial intravitreous injection of conbercept and re-treatment was performed according to the criteria which has been disigned before. BCVA was measured by ETDRS charts. The central macular thickness (CMT), total macular volume (TMV) were measured by Topcon 3D-OCT 2000. The BCVA, CMT and TMV in the combined treatment group and the drug treatment group were 57.9±12.4 letters, 427.8±129.4 μm, 10.14±1.50 mm3 and 59.0±16.0 letters, 441.0 ± 135.7 μm, 10.43±2.10 mm3, respectively. There was no significant difference (t=0.321, 0.410, 0.641; P=0.749, 0.683, 0.524). The follow-up period was more than 12 months. The changes of BCVA, CMT and TMV were compared between the two groups. Comparison of BCVA, CMT, TMV before and after treatment in and between groups using repeated measures analysis of variance. Results The average annual injection times was 5.8±1.9 in the combined treatment group and 8.5±2.4 in the drug treatment group. The difference was statistically significant (t=5.12, P=0.000). The BCVA in the 3rd, 6th, 9th and 12th month were 64.9±11.1, 65.6±10.5, 67.0±10.8, 66.6±10.7 letters and 65.7±15.8, 66.9±15.7, 66.4±13.0, 67.3±16.4 letters, respectively, and there were significant differences compared with BCVA before treatment (F=34.234, 10.137; P=0.000, 0.000). The CMT were 335.2±105.9, 352.6±106.6, 336.2±120.8, 305.9±97.0 μm and 323.9±92.8, 325.5±90.2, 327.6±108.2, 312.2±106.8 μm, respectively. The TMV were 9.20±1.08, 9.26±1.20, 9.20±1.63, 9.05±1.18 mm3 and 9.19±1.21, 9.35±1.69, 9.09±1.20, 8.92±1.10 mm3, respectively. Compared with the CMT (F=12.152, 12.917; P=0.000, 0.000) and TMV (F=11.198, 11.008; P=0.000, 0.000) before treatment, the differences were statistically significant. Conclusion Conbercept combined with 577 nm subthreshold micropulse laser and conbercept can effectively reduce CMT, TMV and improve BCVA in patients with DME, but combination therapy can reduce the injection times of conbercept. Key words: Diabetic retinopathy/complications; Macular edema/drug therapy; Angiogenesis inhibitors/therapeutic use; Antibodies, monoclonal/therapeutic use; Laser coagulation

COMBINATION THERAPY OF INTRAVITREAL RANIBIZUMAB AND SUBTHRESHOLD MICROPULSE PHOTOCOAGULATION FOR MACULAR EDEMA SECONDARY TO BRANCH RETINAL VEIN OCCLUSION: 6-MONTH RESULT.

To determine the efficacy of the combination therapy of intravitreal ranibizumab (IVR) and 577-nm yellow laser subthreshold micropulse laser photocoagulation (SMLP) for macular edema secondary to branch retinal vein occlusion cystoid macular edema. Retrospective, consecutive, case-control study. Forty-six eyes of 46 patients with treatment-naive branch retinal vein occlusion cystoid macular edema were enrolled. The IVR + SMLP group consisted of 22 patients who had undergone both SMLP and IVR. Intravitreal ranibizumab group consisted of 24 patients who had undergone IVR monotherapy. Intravitreal ranibizumab therapy was one initial injection and on a pro re nata in both groups, and SMLP was performed at 1 month after IVR in the IVR + SMLP group. Preoperatively and monthly, best-corrected visual acuity and central retinal thickness were evaluated using swept source optical coherence tomography. Best-corrected visual acuity and central retinal thickness significantly improved at 6 months in IVR + SMLP and IVR groups. Best-corrected visual acuity and central retinal thickness were not significantly different between the two groups at any time points. The number of IVR injections during initial 6 months in IVR group (2.3 ± 0.9) was significantly greater (P = 0.034) than that in IVR + SMLP group (1.9 ± 0.8). The combination therapy of IVR and SMLP can treat branch retinal vein occlusion cystoid macular edema effectively, by decreasing the frequency of IVR injections while maintaining good visual acuity.

Comparison of efficacy and safety of the combined laser treatment technology versus conventional laser photocoagulation in diabetic macular edema management

Aim. To evaluate the efficacy and safety of the novel combined laser treatment technology compared with those of the conventional laser photocoagulation in diabetic macular oedema management.&#x0D; Material and methods. Fifty eyes of 44 patients with clinically significant diabetic macular oedema were enrolled. Patients of the main group (25 eyes) underwent combined laser treatment, whereas patients in the control group (25 eyes) underwent modified ETDRS (mETDRS) focal/grid photocoagulation.&#x0D; Results. Mean central point thickness (CPT) in the main group decreased from 411.24 126 m to 359.86 120.4 m (p 0.05), with a subsequent increase in the mean best-corrected visual acuity (BCVA) from 0.52 0.2 at baseline to 0.71 0.2 (p 0.05) at the 12-month follow-up. The mean central retinal sensitivity (RS) improved from 11.27 3.8 dB to 13.24 3.2 dB (p 0.05). In the control group, our results showed similar improvement in BCVA and CPT values at the 12-month follow-up (from 0.59 0.12 to 0.72 0.23 and from 424.17 68.12 m to 387.51 93.45 m, respectively, p 0.05). The RS value, on the contrary, decreased from 12.32 0.90 dB to 10.14 0.71 dB (p 0.05).&#x0D; Conclusions. The combined laser technology is a safe treatment technique that allows to minimise the extent of laser-induced chorioretinal complex damage due to the contribution of subthreshold micropulse laser photocoagulation. The efficacy of this novel technology is comparable with that of the mETDRS technique in the resolution of macular oedema and BCVA increase. This technology also provides an advantage of RS improvement and the possibility of safe and repetitive treatment sessions.

The Comparative Histologic Effects of Subthreshold 532- and 810-nm Diode Micropulse Laser on the Retina

Therapeutic retinal laser photocoagulation can damage the neurosensory retina and cause iatrogenic visual impairment. Subthreshold micropulse photocoagulation may decrease this risk by selective tissue treatment. The aim of this study was to compare subthreshold 810-nm diode micropulse laser and subthreshold 532-nm micropulse laser on the retina by histologic examination and differential protein expression. Fourteen Dutch-belted rabbits received subthreshold 810-nm diode micropulse laser photocoagulation in their right eye and subthreshold 532-nm micropulse laser photocoagulation in their left eye. Histology and immunohistochemical detection of stromal cell-derived factor-1 (SDF-1), β-actin, vascular endothelial growth factor (VEGF), glial fibrillary acidic protein (GFAP), and insulin-like growth factor 1 (IGF-1) were analyzed 12 hours, 3 days, 14 days, and 28 days post-laser photocoagulation. Histologically, all time points produced a similar degree of retinal disruption in both wavelengths. Immunohistochemically, SDF-1 expression was greatest at the 12-hour time point and decreased thereafter. SDF-1, VEGF, and β-actin up-regulation was detected at early time points in both the 810- and 532-nm micropulse laser-treated animals. Subthreshold micropulse retinal laser photocoagulation caused equivalent histologic changes from both 532- and 810-nm diode lasers. Differential protein expression was not evident between the different laser conditions.