Subthreshold micropulse diode laser photocoagulation for diabetic macular edema in Japanese patients

Subthreshold laser treatment for non-center involved diabetic macular edema via non-damaging retinal laser therapy (NRT)

PURPOSE

To evaluate the efficacy of subthreshold laser treatment via non-damaging retinal laser therapy (NRT) in patients with non-center involved diabetic macular edema (non-CI DME).

METHODS

In this prospective controlled study, NRT with 577 nm wavelength was performed to the edematous inner subfields as needed at 3 monthly intervals, while the control group received no treatment. If CI-DME developed in either group, intravitreal anti-VEGF was performed and the eye was excluded from subsequent analysis.

RESULTS

A total of 75 eyes (36 study eyes, 39 controls) were evaluated. The change in superior, nasal and temporal inner subfield thicknesses over time and between groups was found significant (P = 0.004, P < 0.001, P = 0.04 respectively). Best corrected visual acuity (BCVA) change was not significant over time and between groups (P = 0.69). Rates of CI-DME development requiring intravitreal anti-VEGF treatment were not different during the first and second years (P = 0.171, 0.908). No laser scar was detected in any eye in fundus autofluorescence imaging.

CONCLUSION

NRT performed as needed at 3 monthly intervals is effective after 21 months of follow up in the treatment of non-CI DME and it was safe. With this method, it may be foreseen that BCVA will be better preserved in the long term by avoiding the possible side effects of conventional laser.

Subthreshold micropulse laser therapy for early postoperative macular thickening following surgical removal of epiretinal membrane

BACKGROUND

This study aimed to investigate the functional and anatomical outcomes of subthreshold micropulse laser (SMPL) therapy in eyes with early postoperative macular thickening after idiopathic epiretinal membrane (iERM) removal.

METHODS

This was a prospective and interventional study. Forty-eight eyes from 48 patients with macular edema at 1 month after iERM removal were randomly divided into two groups. Patients in the SMPL group (n = 24) received SMPL therapy while no special intervention was used for the observation group (n = 24). Baseline demographic data and clinical findings before and at 1 and 3 months after SMPL treatment or observation, including best-corrected visual acuity (BCVA) and the changes in central subfield thickness (CST) and average macular thickness (AMT), were analyzed.

RESULTS

An improvement in BCVA with a decrease in CST and AMT from baseline to the 3-month follow-ups were observed in both SMPL and observation groups. No significant difference in BCVA was observed between the SMPL group and observation group either in the 1-month (0.26 [0.15, 0.52] vs. 0.26 [0.15, 0.39], P = 0.852) or the 3-month (0.15 [0.10, 0.30] vs. 0.23 [0.15, 0.30], P = 0.329) follow-up. There was a greater reduction in CST in the SMPL group versus observation group between baseline and the 3-month follow-up (-77.8 ± 72.3 μm vs. -45.0 ± 46.9 μm, P = 0.049). The alteration in AMT did not differ between the two groups in either 1-month (-16.5 ± 20.1 μm vs. -19.7 ± 16.3 μm, P = 0.547) or 3-month (-36.9 ± 26.9 μm vs. -34.0 ± 20.1 μm, P = 0.678) follow-up.

CONCLUSIONS

SMPL therapy led to a significant decrease in CST at the 3-month follow-up while did not significantly improve the visual acuity in patients with postoperative macular thickening following iERM surgery.

TRIAL REGISTRATION

The study was registered on Aug 27, 2020 (Trial Registration Number: ChiCTR 2000037227).

The Role of Laser Photocoagulation in Treating Diabetic Macular Edema in the Era of Intravitreal Drug Administration: A Descriptive Review

Background and Objectives: This study aimed to elucidate the role of laser photocoagulation therapy in the treatment of diabetic macular edema (DME) as an alternative to, or in conjunction with, the first-line treatment, anti-vascular endothelial growth factor (VEGF). Materials and Methods: A comprehensive literature search to identify studies that evaluated the efficacy of laser photocoagulation therapy in the management of DME was performed. The relevant findings of the efficacy of focal/grid laser therapy from data in randomized, controlled trials were synthesized, and the potential of new laser technologies, such as navigated laser systems, pattern scan lasers, and subthreshold lasers, was explored. The usefulness of multimodal imaging-guided laser therapy was also evaluated, with a focus on the potential contribution to anti-VEGF therapy. Results: Focal laser photocoagulation targeting microaneurysms remains an effective therapeutic approach to chronic refractory edema, despite the widespread use of anti-VEGF therapy. To achieve the best possible treatment outcomes, precise identification of microaneurysms is essential. This requires the use of multimodal imaging-guided, highly accurate, minimally invasive coagulation techniques. Subthreshold laser therapy can also reduce the frequency of anti-VEGF injections and minimize treatment burden. Conclusions: Further studies are needed to determine the optimal timing and settings for laser photocoagulation therapy and the potential of new laser technologies in the management of DME. Nevertheless, laser photocoagulation therapy plays an important role in the management of DME, in conjunction with anti-VEGF therapy.

Current Treatments for Diabetic Macular Edema

Diabetic retinopathy is a major retinal disorder and a leading cause of blindness. Diabetic macular edema (DME) is an ocular complication in patients with diabetes, and it can impair vision significantly. DME is a disorder of the neurovascular system, and it causes obstructions of the retinal capillaries, damage of the blood vessels, and hyperpermeability due to the expression and action of vascular endothelial growth factor (VEGF). These changes result in hemorrhages and leakages of the serous components of blood that result in failures of the neurovascular units (NVUs). Persistent edema of the retina around the macula causes damage to the neural cells that constitute the NVUs resulting in diabetic neuropathy of the retina and a reduction in vision quality. The macular edema and NVU disorders can be monitored by optical coherence tomography (OCT). Neuronal cell death and axonal degeneration are irreversible, and their development can result in permanent visual loss. Treating the edema before these changes are detected in the OCT images is necessary for neuroprotection and maintenance of good vision. This review describes the effective treatments for the macular edema that are therefore neuroprotective.

Microperimetric analysis of diabetic macular edema after navigated direct photocoagulation with short-pulse laser for microaneurysms

BACKGROUND

Focal laser photocoagulation is an important treatment option for diabetic macular edema (DME). This study aimed to examine the retinal sensitivity (RS) and morphological changes at the coagulated site after direct photocoagulation of microaneurysms (MAs) in patients with DME using a navigated laser photocoagulator with a short-pulse duration of 30 ms.

METHODS

Images of early-phase fluorescein angiography were merged with images from the optical coherence tomography (OCT) map with 9 Early Treatment Diabetic Retinopathy Study grid circles, and MAs inside the edema area were selected for direct photocoagulation. The best-corrected visual acuity (BCVA), parameters of the OCT map including central retinal thickness and retinal thickness in edema range, central RS, and RS in the edema area were assessed at 1 and 3 months after the laser treatment. The RS points that overlapped with the laser spots were identified by merging the Navilas' digital treatment reports and the microperimetry images.

RESULTS

Seventeen eyes from 14 patients were studied. The mean retinal thickness in the edema range decreased at 3 months compared with pretreatment (P = 0.042), but the BCVA, central retinal thickness, central RS, and RS in the edema area remained unchanged. Overall, 32 of 400 sensitivity points overlapped with the laser-coagulated spots. The mean RS at these spots were 22.4 ± 5.3 dB at 1 month and 22.5 ± 4.8 dB at 3 months, with no significant change from the baseline of 22.7 ± 3.5 dB.

CONCLUSIONS

Retinal thickness improved in the coagulated edema area without a decrease in RS after direct photocoagulation of MAs with a short 30-ms pulse using Navilas. This promising therapeutic strategy for DME is effective and minimally invasive.

Subthreshold Micropulse Laser for Diabetic Macular Edema: A Review

Diabetic macular edema (DME) is one of the main causes of visual impairment in patients of working age. DME occurs in 4% of patients at all stages of diabetic retinopathy. Using a subthreshold micropulse laser is an alternative or adjuvant treatment of DME. Micropulse technology demonstrates a high safety profile by selectively targeting the retinal pigment epithelium. There are no standardized protocols for micropulse treatment, however, a 577 nm laser application over the entire macula using a 200 μm retinal spot, 200 ms pulse duration, 400 mW power, and 5% duty cycle is a cost-effective, noninvasive, and safe therapy in mild and moderate macular edemas with retinal thickness below 400 μm. Micropulse lasers, as an addition to the current gold-standard treatment for DME, i.e., anti-vascular endothelial growth factor (anti-VEGF), stabilize the anatomic and functional retinal parameters 3 months after the procedure and reduce the number of required injections per year. This paper discusses the published literature on the safety and application of subthreshold micropulse lasers in DME and compares them with intravitreal anti-VEGF or steroid therapies and conventional grid laser photocoagulation. Only English peer-reviewed articles reporting research within the years 2010-2022 were included.

Temperature Increase and Damage Extent at Retinal Pigment Epithelium Compared between Continuous Wave and Micropulse Laser Application

Continuous wave (CW) and microsecond pulse (MP) laser irradiations were compared regarding cell damage and laser-induced temperature rise at retinal pigment epithelium (RPE). The RPE of porcine RPE-choroid-sclera explants was irradiated with a 577 nm laser in CW or MP mode (5% or 15% duty cycle (DC)) for 20 ms or 200 ms at an average laser power of 20−90 mW. Cell viability was investigated with calcein-AM staining. Optoacoustic (OA) technique was employed for temperature measurement during irradiation. For 200 ms irradiation, the dead cell area (DCA) increased linearly (≈1600 µm2/mW) up to the average power of 40 mW for all modes without significant difference. From 50 mW, the increase of DCA of MP-5% significantly dropped to 610 µm2/mW (p < 0.05), likely due to the detected microbubble formation. OA temperature measurement showed a monotonic temperature increase in CW mode and a stepwise increase in MP mode, but no significant difference in the average temperature increase at the same average power, consistent with the temperature modeling. In conclusion, there is no difference in the average temperature rise between CW and MP modes at the same average power regardless of DC. At lower DC, however, more caution is required regarding mechanical damage due to microbubble formation.

Randomized clinical trial comparing intravitreal aflibercept combined with subthreshold laser to intravitreal aflibercept monotherapy for diabetic macular edema

To compare the efficacy and safety of intravitreal aflibercept with three loading doses + pro re nata regimen combined with subthreshold laser application to that of IVA monotherapy on eyes with diabetic macular edema. This was a phase 4 clinical trial with a prospective, randomized, and parallel investigator-driven protocol. Patients with DME were randomly assigned to the IVA monotherapy group (n = 25) or the IVA + SL combination therapy group (n = 26). The main outcome measures were the number of IVA injections and the changes in the best-corrected visual acuity (BCVA) and the central retinal thickness (CRT) at the final evaluation at 96 weeks. The mean number of IVA injections in the monotherapy group was 5.86 ± 2.43 and it was 6.05 ± 2.73 in the IVA + SL group at 96 weeks, and this difference was not significant (P = 0.83). The differences in the mean changes of the CRT (P = 0.17) and the BCVA (P = 0.31) were also not significant between the two groups throughout the follow-up period. We conclude that adjunct of SL to anti-VEGF therapy does not reduce the number of necessary intravitreal injections.

Differential gene expression analysis using RNA sequencing: retinal pigment epithelial cells after exposure to continuous-wave and subthreshold micropulse laser

PURPOSE

Subthreshold micropulse laser (SMPL) is more clinically efficient for the treatment of diabetic macular edema (DME) than the conventional continuous-wave (CW) laser. We aimed to characterize transcriptome changes after the application of these lasers and to compare the transcripts.

METHODS

Human pluripotent stem cell-derived retinal pigment epithelial cells were exposed to laser irradiation. Differentially expressed genes (DEGs), distribution of heat shock protein (Hsp) family, gene expression profile, and gene ontology (GO) enrichment analysis based on RNA sequencing data were investigated at 3 h and 24 h after irradiation.

RESULTS

CW laser induced more DEGs than SMPL (1771 vs. 520 genes). The expression of the Hsp family was confirmed in both groups: however, the induction patterns was different for different genes. GO enrichment analysis revealed that CW laser upregulated the expression of DEGs involved in vasculature development (GO: 0001944), related to apoptosis and repair after cell injury whereas SMPL upregulated the expression of DEGs involved in photoreceptor cell maintenance (GO: 0045494), photoreceptor cell development (GO: 0042461), and sensory perception of light stimuli (GO: 0050953).

CONCLUSIONS

The results provide insights into the genetic responses and may contribute to the understanding of the molecular mechanisms of laser-induced thermal effects.

Comparison of the 1-Year Visual and Anatomical Outcomes between Subthreshold Red (670 nm) and Yellow (577 nm) Micro-Pulse Laser Treatment for Diabetic Macular Edema

We investigated the efficacy and safety of red (670 nm) subthreshold micropulse laser (SMPL) treatment for diabetic macular edema (DME) and compared the 1-year treatment outcomes of red and yellow (577 nm) SMPL for DME. A medical chart review was performed in 43 consecutive eyes of 35 patients who underwent red or yellow SMPL treatment for DME and were followed up for 12 months. There were 26 and 17 eyes in the yellow and red SMPL groups, respectively. The mean best-corrected visual acuity (BCVA) was maintained throughout the follow-up period of 12 months in the yellow and red SMPL groups (p = 0.39, p = 0.70, respectively). The central retinal thickness (CRT) measured by spectral-domain optical coherence tomography (SD-OCT) was significantly decreased at 12 months from baseline in the yellow and red SMPL groups (p = 0.047, p = 0.03, respectively). Although the amount of CRT reduction in the red SMPL group was significantly greater than that in the yellow SMPL group at 8 months from baseline (p = 0.02), the significance disappeared at the final follow-up period (p = 0.44). The red SMPL maintained the BCVA in patients with center-involving DME. The mean CRT in the red SMPL group significantly decreased, and the amount of CRT reduction was equivalent to that in the yellow SMPL group.

Updates on the Current Treatments for Diabetic Retinopathy and Possibility of Future Oral Therapy

Diabetic retinopathy (DR) is a complication of diabetes and one of the leading causes of vision loss worldwide. Despite extensive efforts to reduce visual impairment, the prevalence of DR is still increasing. The initial pathophysiology of DR includes damage to vascular endothelial cells and loss of pericytes. Ensuing hypoxic responses trigger the expression of vascular endothelial growth factor (VEGF) and other pro-angiogenic factors. At present, the most effective treatment for DR and diabetic macular edema (DME) is the control of blood glucose levels. More advanced cases require laser, anti-VEGF therapy, steroid, and vitrectomy. Pan-retinal photocoagulation for non-proliferative diabetic retinopathy (NPDR) is well established and has demonstrated promising outcomes for preventing the progressive stage of DR. Furthermore, the efficacy of laser therapies such as grid and subthreshold diode laser micropulse photocoagulation (SDM) for DME has been reported. Vitrectomy has been performed for vitreous hemorrhage and tractional retinal detachment for patients with PDR. In addition, anti-VEGF treatment has been widely used for DME, and recently its potential to prevent the progression of PDR has been remarked. Even with these treatments, many patients with DR lose their vision and suffer from potential side effects. Thus, we need alternative treatments to address these limitations. In recent years, the relationship between DR, lipid metabolism, and inflammation has been featured. Research in diabetic animal models points to peroxisome proliferator-activated receptor alpha (PPARα) activation in cellular metabolism and inflammation by oral fenofibrate and/or pemafibrate as a promising target for DR. In this paper, we review the status of existing therapies, summarize PPARα activation therapies for DR, and discuss their potentials as promising DR treatments.

Determination of Micropulse Modes with Targeted Damage to the Retinal Pigment Epithelium Using Computer Modeling for the Development of Selective Individual Micropulse Retinal Therapy

PURPOSE

When using a serial laser system for selective impact on the retinal pigment epithelium (RPE), there is a challenge to determine the optimal range of micropulse parameters which result in targeted damage to the RPE. This study proposes a computer model that has identified the optimal parameters to be applied.

METHODS

This study was conducted on 18 patients who were diagnosed with acute central serous chorioretinopathy and transparent optical media, aged 35 to 46 years old, and type 2 and 3 on the Fitzpatrick scale. Testing of the micropulse mode was performed on the Navilas 577s laser system; 864 spots were analyzed in total. Considering the probability of damage visualization at different laser power, the computer simulation of tissue heating and protein denaturation was performed to determine the micropulse modes which resulted in selective damage to the RPE.

RESULTS

The computer model parameter ΔE = 3.34 × 10⁵ J/mol was determined from fitting the model predictions to the autofluorescence test results. The micropulse modes with a micropulse duration of 50-100 µs, duty cycle 2.4-4.8%, 10 ms-pulse envelope (5 micropulses), and spot diameter of 100 µm have efficiency and selectivity above 67% and correspond to the optimal therapeutic window for targeted RPE damage at a certain power. Increasing the micropulse duration, number of micropulses, and duty cycle leads to a decrease in the selective effect on the RPE and higher damage to adjacent tissues.

CONCLUSION

The concepts of efficiency and selectivity have been introduced to quantify the amount of damage caused. The optimal range of micropulse parameters which result in effective and selective damage on the RPE has been determined for the Navilas 577s laser system. The proposed method can be used for any other serial laser system. A comparison of the different micropulse modes, as well as the CW modes, has been performed.

Changes in entropy on polarized-sensitive optical coherence tomography images after therapeutic subthreshold micropulse laser for diabetic macular edema: A pilot study

Purpose

To investigate the dynamics of the healing process after therapeutic subthreshold micropulse laser (SMPL) for diabetic macular edema (DME) using polarization-sensitive optical coherence tomography (PS-OCT).

Methods

Patients with treatment-native or previously-treated DME were prospectively imaged using PS-OCT at baseline, 1, 2, 3, and 6 months. The following outcomes were evaluated: changes in the entropy value per unit area (pixel²) in the retinal pigment epithelium (RPE) on the B-scan image; changes in the entropy value in each stratified layer (retina, RPE, choroid) based on the ETDRS grid circle overlaid with en face entropy mapping, not only the whole ETDRS grid area but also a sector irradiated by the SMPL; and the relationship between edema reduction and entropy changes.

Results

A total of 11 eyes of 11 consecutive DME patients were enrolled. No visible signs of SMPL treatment were detected on PS-OCT images. The entropy value per unit area (pixel²) in the RPE tended to decrease at 3 and 6 months from baseline (35.8 ± 17.0 vs 26.1 ± 9.8, P = 0.14; vs 28.2 ± 18.3, P = 0.14). Based on the en face entropy mapping, the overall entropy value did not change in each layer in the whole ETDRS grid; however, decrease of entropy in the RPE was observed at 2, 3, and 6 months post-treatment within the SMPL-irradiated sectors (P < 0.01, each). There was a positive correlation between the change rate of retinal thickness and that of entropy in the RPE within the SMPL-irradiated sector at 6 months (r² = 0.19, P = 0.039).

Conclusion

Entropy measured using PS-OCT may be a new parameter that facilitates objective monitoring of SMPL-induced functional changes in the RPE that could not previously be assessed directly. This may contribute to a more promising therapeutic evaluation of DME.

Clinical trial

This clinical study was registered in UMIN-CTR (ID: UMIN000042420).

Subthreshold Micropulse Laser vs. Conventional Laser for Central Serous Chorioretinopathy: A Randomized Controlled Clinical Trial

Purpose: To investigate the effectiveness and safety of 577-nm subthreshold micropulse laser (SML) on acute central serous chorioretinopathy (CSC). Methods: One hundred and ten patients with acute CSC were randomized to receive SML or 577-nm conventional laser (CL) treatment. Optical coherence tomography and best-corrected visual acuity (BCVA) were performed before and after treatment. Results: At 3 months, the complete resolution of subretinal fluid (SRF) in 577-nm SML group (72.7%) was lower than that in CL group (89.1%) (Unadjusted RR, 0.82; P = 0.029), but it was 85.5 vs. 92.7% at 6 months (unadjusted RR, 0.92; P = 0.221). The mean LogMAR BCVA significantly improved, and the mean central foveal thickness (CFT) significantly decreased in the SML group and CL group (all P < 0.001) at 6 months. But there was no statistical difference between the two groups (all P > 0.05). In the SML group, obvious retinal pigment epithelium (RPE) damage was shown only in 3.64% at 1 month but 92.7% in the CL group (P < 0.001). Conclusions: Although 577-nm SML has a lower complete absorption of SRF compared with 577-nm CL for acute CSC at 3 months, it is similarly effective as 577-nm CL on improving retinal anatomy and function at 6 months. Importantly, 577-nm SML causes less damage to the retina.

Comparison of two-year treatment outcomes between subthreshold micropulse (577 nm) laser and aflibercept for diabetic macular edema

PURPOSE

To compare two-year treatment outcomes of subthreshold micropulse (577 nm) laser and aflibercept for diabetic macular edema (DME).

STUDY DESIGN

Retrospective case-control study.

METHODS

A total 164 eyes in 164 DME patients treated with either micropulse laser (86 eyes) or intravitreal aflibercept monotherapy (78 eyes) were recruited. Main outcome measures included at least five Early Treatment Diabetic Retinopathy Study (ETDRS) letters' improvement from baseline at 6, 12 and 24 months.

RESULTS

Rescue aflibercept was initiated in 24% of eyes in micropulse laser group. At 6-month visit the aflibercept group achieved a higher percentage of eyes with at least 5-letter visual acuity improvement than micropulse laser group (56% vs 38%, P = 0.044), however, this was not the case at 12-month (45% vs 49%, P = 0.584) and 24-month visits (49% vs 57%, P = 0.227). At 6-month visit the aflibercept group achieved a higher percentage of eyes with at least 10% improvement of central macular thickness (73% vs 49%, P = 0.005), but this was not the case at 12-month (73% vs 70%, P = 0.995) and 24-month visits (85% vs 84%, P = 0.872).

CONCLUSION

Aflibercept achieved faster and higher rates of anatomical and functional improvement than micropulse laser in DME patients. Long term efficacy of treatment did not result in significant differences between aflibercept monotherapy and micropulse laser in DME patients. Primary treatment of micropulse laser with deferred rescue aflibercept might be the treatment option without reducing the chance of visual improvement in DME eyes.

Does conventional laser photocoagulation still have a place in the treatment of diabetic macular edema?

Objective: The study aimed to investigate the long-term efficacy of conventional laser photocoagulation in the treatment of diabetic macular edema. Methods: In this retrospective study, the records of patients presented with diabetic macular edema (DME) and non-proliferative diabetic retinopathy were reviewed. DME defined as clinically significant macular edema was treated by using argon green or yellow dye laser with focal, grid, and modified grid techniques according to Early Treatment Diabetic Retinopathy Study parameters. Best-corrected visual acuity (BCVA) was measured. BCVA change after the treatment and its relationship with other factors were evaluated. Results: The study included 133 eyes of 81 patients. The mean follow-up was 28.26 months. BCVA demonstrated the increase of 2 lines or more in 20.7% of the eyes, stabilization within 2 lines in 60.7% of the eyes, and loss of 2 lines or more in 18.3% of the eyes. The eyes with baseline BCVA lower than or equal to 0.50 showed a statistically significant increase (p=0.001) whereas the eyes with baseline BCVA of more than 0.50 did not show a statistically significant change (p=0.070) after laser photocoagulation treatment. Conclusions: Conventional laser photocoagulation is an effective treatment in diabetic macular edema including center-involved type and stabilizes visual acuity in the majority of the patients. Improvement in BCVA is significant in the group with lower baseline BCVA. Abbreviations: DM = diabetes mellitus, DME = diabetic macular edema, ETDRS = early treatment diabetic retinopathy study, CSME = clinically significant macular edema, CLP = conventional laser photocoagulation, VEGF = vascular endothelial growth factor, BCVA = best-corrected visual acuity, ANOVA = analysis of variance, VA = visual acuity.

Micropulse laser in patients with refractory and treatment-naïve center-involved diabetic macular edema: short terms visual and anatomic outcomes

Purpose:

The purpose of the study is to describe visual and anatomic outcomes of 5774nm micropulse laser photocoagulation in eyes with either treatment-naïve or refractory diabetic macular edema (DME) at 3 months.

Methods:

This was a prospective case series that recruited 23 consecutive patients (33 eyes) with center-involved DME that was either treatment-naïve or had not responded to prior treatment. Micropulse therapy was performed with the Easy Ret 577 (Quantel Medical, Cournon d’Auvergne, France) diode laser in a high-density manner in eyes with treatment-naïve or refractory DME. The primary outcome was the change of best-corrected visual acuity (BCVA; logMAR) at 1 and 3 months. Secondary outcomes were changes in the central macular thickness (CMT), thickness area, macular volume, and macular capillary leakage at 1 and 3 months.

Results:

There were no significant changes in BCVA at 3 months, with mean ± standard deviation (SD) of −0.08 ± 0.01 (p = 0.228) and + 0.01 ± 0.01 (p = 0.969) for treatment-naïve and refractory groups, respectively. The change in CMT at 3 months was statistically but not clinically significant in the treatment-naïve group only (mean ± SD; –30 ± 130 µm; p = 0.011). The macular volume and area thickness change were not statistically significant (p = 0.173 and p = 0.148 for macular volume and area thickness, respectively) in the treatment-naïve group. There was no difference concerning the leakage area in both groups. No adverse events were reported.

Conclusion:

We concluded that micropulse 577nm laser therapy maintained the visual acuity and macular thickness at 3 months in both treatment-naïve and refractory DME.

Anatomical and functional outcomes of subthreshold micropulse laser versus intravitreal ranibizumab injection in treatment of diabetic macular edema

Background

To compare the therapeutic effects of subthreshold micropulse laser (SML) versus intravitreal injection of ranibizumab in treatment of diabetic macular edema (DME) both anatomically using optical coherence tomography (OCT) and functionally using best corrected visual acuity (BCVA) and multifocal electroretinogram (mfERG).

Methods

his study was an interventional prospective randomized comparative study. The study included 120 eyes classified into 3 groups: Group 1 included 40 eyes of 28 patients treated by SML laser, group 2 included 40 eyes of 32 patients treated by intravitreal injection of ranibizumab, and group 3 (control group for mfERG) included 40 eyes of 20 patients with diabetes mellitus (DM) of more than 10 year duration with no signs of diabetic retinopathy (DR). BCVA measurements, OCT and mfERG were done for the cases before and after interference and were followed up for 6 months

Results

By the end of the follow up period, BCVA significantly improved by 31% in group 1 vs 93% in group 2 with a statistically highly significant difference between the two groups (p value < 0.001). There was also a significant decrease in central subfield thickness in both groups with more reduction in group 2 compared with group 1 (p value < 0.001). There was a significant improvement in P1 amplitude of mf-ERG in group 2 (p value < 0.002) with no significant improvement in group 1. There was a significant decrease in P1 implicit time in group 2 (p value < 0.001) while there was no significant decrease in group1.

Conclusions

Intravitreal injection of ranibizumab is a superior treatment modality for DME compared with SML regarding both anatomical and functional outcomes.

Trial registration: This study has been approved by the local ethical committee of faculty of medicine of Minia University and retrospectively registered at the clinical trial gov. with Identifier: NCT04332133.

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

This study suggests that the combination therapy of intravitreal ranibizumab and 577-nm subthreshold micropulse photocoagulation can treat macular edema secondary to macular edema secondary to branch retinal vein occlusion effectively, by decreasing the frequency of intravitreal ranibizumab injections than intravitreal ranibizumab monotherapy while maintaining good visual acuity at 6 months.

Purpose:

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.

Methods:

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.

Results:

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).

Conclusion:

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.

Macular laser photocoagulation in the management of diabetic macular edema: Still relevant in 2020?

Macular laser photocoagulation (MLP) is inferior to intravitreal vascular endothelial growth factor (VEGF) inhibitors in the treatment of center-involved diabetic macular edema (DME). Ultra-widefield fluorescein angiography-guided laser photocoagulation to presumed ischemic areas of the peripheral retina or MLP do not reduce the treatment burden nor improve the visual outcomes of eyes treated with anti-VEGF drugs. Destruction of retinal tissue is not necessary to induce a therapeutic response in DME. Modern lasers are capable of producing invisible laser "burns" that do not destroy the targeted tissue using micropulse subthreshold (ST) mode where the laser's duty cycle is modified or alternatively selective retinal therapy (SRT) where ultrashort pulses of continuous wave laser selectively target the RPE. The best results with micropulse ST laser are obtained in eyes with a central macular thickness ≤400 μm. Eyes need to be treated in a continuous manner with no spaces between burns in the edematous area. Micropulse ST-MLP downregulates inflammatory biomarkers produced by activated microglial cells and Müller cells. Micropulse ST-MLP may reduce the anti-VEGF injection burden in DME. In SRT, the diseased RPE is targeted and heated with the laser with the hope that the adjacent RPE migrates and proliferates into these areas to heal the diseased RPE. There is much less experience with SRT, but the results are promising and deserve further study.

Predictive factors of outcome of selective retina therapy for diabetic macular edema

PURPOSE

To investigate the predictive factors of clinical outcome of selective retina therapy (SRT) for diabetic macular edema (DME).

METHODS

This retrospective study included 22 eyes of 22 patients (15 males and 7 females), who were treated with SRT for DME at the Department of Ophthalmology of Osaka City University Hospital and observed at least 6 months after the treatment. The mean age was 64 years (range 40-81). Thirteen of the 22 eyes (59%) had a treatment history other than SRT before. SRT laser (527 nm, 1.7 µs, 100 Hz) was used for treatment. Changes in the best-corrected visual acuity (BCVA) (logMAR) and central macular thickness (CMT) in optical coherence tomography were examined at baseline, 3-month follow-up, and 6-month follow-up. Factors associated with the rate of change in CMT at 3 and 6 months after SRT were examined.

RESULTS

The mean BCVA (logMAR) was 0.26 ± 0.31, 0.22 ± 0.27 and 0.23 ± 0.29 at baseline, 3 months and 6 months, respectively (p = 0.15 at 3 months, 0.40 at 6 months; compared to baseline). The mean CMT was 502 ± 163, 493 ± 204, and 416 ± 185 μm at baseline, 3 months, and 6 months, respectively (p = 0.69 at 3 months, 0.01 at 6 months; compared to baseline). The multivariate analysis found a significant negative association with previous macular photocoagulation (p = 0.03) at 3 months and a positive association with a history of insulin use (p = 0.02) and previous panretinal photocoagulation (p = 0.03) at 6 months after SRT.

CONCLUSION

The CMT was significantly decreased at 6 months after SRT in DME. The history of insulin use and panretinal photocoagulation may positively and the history of macular photocoagulation may negatively affect the outcome of SRT, which must be considered when determining the therapeutic indications for SRT.

En-Face Optical Coherence Tomography Angiography for Longitudinal Monitoring of Retinal Injury

A customized Optical Coherence Tomography Angiography (OCTA) algorithm and Orthogonal OCT (en-face and B-Scans) were used for longitudinal assessment of retina murine vascular and tissue remodeling comparing photoreceptor ablation and laser-induced Choroidal Neovascularization (CNV). In the mouse model, we utilized a combined OCTA/OCT technique to image and quantify morphological and vascular features of laser lesions over time. This approach enabled us to monitor and correlate the dynamics of retina vascular and tissue remodeling as evidenced by swelling, edema, and scarring. From the OCT B-Scans, three stages of inflammatory progression were identified: the early response occurring within hours to day 3, the transition phase from 3-7 days, and the late stage of 7-21 days entering either the resolving phase or chronic phase, respectively. For the case of CNV, en-face OCTA revealed a transient non-perfusion of inner retina capillaries, specifically Deep Vascular Plexus (DVP), which corresponded to growth in lesions of a height of 200 μm or greater. Non-perfusion first occurred at 24 hours, persisted during edema and CNV formation days 7-14. In contrast, the acute inflammation induced photoreceptor damage, but no detectable alterations to the microvasculature were observed. We demonstrated that the en-face OCTA system is capable of visualizing capillary networks (~5 μm) and the corresponding tissue remodeling and growth dynamics allowing for separating acute injury from CNV. For the first time, by using OCTA we observed the presence of the 5-10 μm capillary non-perfusion present in DVP as part of CNV formation and the associated wound healing in the retina.

The subthreshold micropulse laser treatment of the retina restores the oxidant/antioxidant balance and counteracts programmed forms of cell death in the mice eyes

PURPOSE

Subthreshold micropulse laser (SMPL) has been increasingly used for the treatment of different retinal and choroidal macular disorders. However, the exact mechanisms of action have not yet been clearly defined. Therefore, we aimed to examine the role of SMPL treatment in the modulation of oxidant/antioxidant systems, apoptosis and autophagy in the mice eyes.

METHODS

A specific laser contact lens for retina was positioned on the cornea of 40 mice (20 young and 20 old) in order to focus the laser on the eye fundus for SMPL treatment. Within 6 months, 20 animals received one treatment only, whereas the others were treated three times. Eye specimens underwent histological analysis and were used for thiobarbituric acid reactive substances (TBARS) and glutathione (GSH) quantification, as well as for the superoxide dismutase 1 (SOD1) and the selenoprotein thioredoxin reductase 1 (TrxR1) expression evaluation. Western blot was performed for nitric oxide synthase (NOS) subtypes detection and to examine changes in apoptotic/autophagy proteins expression.

RESULTS

SMPL treatment reduced TBARS and increased GSH and SOD1 in the mice eyes. It also reduced cytochrome c, caspase 3 expression and activity and cleaved caspase 9, and increased Beclin 1, p62 and LC3β. The effects were more relevant in the elderly animals.

CONCLUSION

Our results showed that SMPL therapy restored the oxidant/antioxidant balance within retinal layers and modulated programmed forms of cell death. Further studies may confirm these data and could evaluate their relevance in clinical practice.

Minimally invasive laser treatment combined with intravitreal injection of anti-vascular endothelial growth factor for diabetic macular oedema

The purpose of this study was to investigate the effect of the combination of minimally invasive laser treatment to the intravitreal injection of anti-vascular endothelial growth factor (VEGF) for diabetic macular oedema (DME). This study was retrospective longitudinal study of thirty-four eyes of 31 patients with DME. Either once or several times of intravitreal anti-VEGF injection was followed by the single minimally invasive laser within a month. The mean best corrected visual acuity (VA) and the central macular thickness (CMT) were measured before treatment, 1, 3, 6 and 12 months after the first anti-VEGF injection. The mean logMAR VA had improved from 0.52 ± 0.34 at baseline to 0.44 ± 0.32 (p = 0.003), 0.40 ± 0.34 (p = 0.006), 0.43 ± 0.33 (p = 0.063), and 0.41 ± 0.34 (p = 0.009), at 1, 3, 6, and 12 months after treatment, respectively. The mean CMT decreased significantly by 1 month and maintained over 12 months (491.1 ± 133.9 µm at baseline, 396.6 ± 116.8 µm (p = 0.001), 385.2 ± 156.2 µm (p = 0.002), 336.5 ± 86.3 µm (p = 0.000), and 354.8 ± 120.4 µm (p = 0.000) at 1, 3, 6, and 12 months, respectively). The average number of the anti-VEGF injection in 1 year was 3.6 ± 2.1 in all patients. The combined intravitreal anti-VEGF and minimally invasive laser therapy improves the VA, alleviates DME, and may decrease the required number of anti-VEGF injections.

Micropulse Laser Treatment of Retinal Diseases

Subthreshold micropulse laser treatment has been intensively used for selected retinal diseases in the last decade; however, the exact mechanism of the action of lasers in the subthreshold micropulse mode is not yet fully understood. This kind of treatment is safe and cheap, and contrary to classic laser photocoagulation, it leaves the retinal cells intact. A modern theory of micropulse laser interaction with retinal tissue and a possible explanation of this mechanism are presented in this review. The authors present all the relevant literature on the application of micropulse lasers in different retinal disorders. The efficacy of this treatment is analyzed on the basis of available studies and then placed in the perspective of other therapeutic methods that are used in retinal diseases.

A pilot prospective study of 577-nm yellow subthreshold micropulse laser treatment with two different power settings for acute central serous chorioretinopathy

To compare the efficacy of 50% threshold power with 25% threshold power of 577-nm subthreshold micropulse laser (SMPL) for acute central serous chorioretinopathy (CSC). Prospective, interventional, non-randomized, comparative case series. A total of 54 patients (54 eyes) with acute CSC were enrolled. Twenty-four eyes received 25% threshold power and 30 eyes received 50% threshold power of 577-nm SMPL. Best-corrected visual acuity (BCVA), central macular thickness (CMT), and complete absorption of subretinal fluid (SRF) were evaluated at 1 month and 3 months. The complete absorption rate of SRF in the 50% power group was significantly greater than that in the 25% power group at 1 month (70.0% vs 25.0%, p < 0.001) and at 3 months (83.3% vs 54.2%, p < 0.001). Mean BCVA improved from 0.34 ± 0.20 LogMAR to 0.02 ± 0.13 LogMAR in the 50% power group and from 0.27 ± 0.15 LogMAR to 0.14 ± 0.21 LogMAR in the 25% power group with a significant difference between the two groups after 3 months (p = 0.027). In the 50% power group, the CMT decreased from 491.6 ± 154.8 μm at baseline to 231.3 ± 92.3 μm at 1 month and 228.2 ± 88.1 μm at 3 months, and in the 25% power group, the CMT decreased from 444.9 ± 164.1 to 306.8 ± 102.6 μm at 1 month and 254.5 ± 101.7 μm at 3 months. There was statistical difference of CMT at 1 month (p = 0.009) but no significant difference at 3 months between the two groups (p = 0.232). SMPL with 50% threshold power may be more effective than 25% threshold power for acute CSC.

Effects of subthreshold diode micropulse laser photocoagulation on treating patients with refractory diabetic macular edema

Purpose

To evaluate the effects of subthreshold diode micropulse laser photocoagulation on treating patients with refractory diabetic macular edema (DME).

Methods

This randomized clinical trial recruited patients with DME in both eyes that were resistant to treatment with intravitreal bevacizumab (IVB). The eyes were randomly divided into two groups who received laser therapy and IVB, or IVB alone. Subthreshold diode micropulse laser photocoagulation and IVB injection were administered in one eye, and an IVB injection was administered in the second eye. IVB injections were repeated in both eyes within one month and two months after the first injection. Best corrected visual acuity (BCVA) logarithm of the minimum angle of resolution (logMAR) and central macular thickness (CMT) were measured before, within a month, and three months after start of intervention.

Results

In this study, 42 eyes of 21 patients were evaluated. The mean age of patients was 60.86 ± 8.57 years. Ten patients (47.6%) were male. Within-group analysis showed a significant decreased in BCVA logMAR in the laser + IVB group reflecting improvement in visual acuity (VA) (P < 0.001); it increased in the control group during study reflecting more vision loss (P = 0.01). In the laser + IVB group, a significant decrease in mean ± standard deviation (SD) CMT at 3 months compared to baseline was observed (baseline: 513 ± 126.29 vs. three months: 408.1 ± 95.28; P < 0.001). The mean ± SD CMT was significantly lower in the laser + IVB group of eyes than in the control group three months after intervention (P = 0.02).

Conclusion

Using subthreshold diode micropulse laser photocoagulation in combination with IVB can significantly reduce CMT and improve BCVA in patients with refractory DME.

Comparison of photodynamic therapy and navigated microsecond laser for chronic central serous chorioretinopathy

OBJECTIVES

To compare the visual and anatomical outcomes after photodynamic therapy (PDT) and navigated microsecond laser (nMSL) for chronic central serous chorioretinopathy (CSCR).

METHODS

This retrospective study included eyes with chronic CSCR who underwent either PDT or nMSL with a minimum of 6 months' follow-up. Eyes with a history of treatment with any other modalities in the past or during 6 months post PDT or microsecond laser follow-up were excluded. Primary outcome measures included change in best-corrected visual acuity (BCVA) and central macular thickness (CMT). Secondary outcome measures included changes in subretinal fluid, hyper-reflective foci, cystic spaces, subfoveal choroidal thickness, and outer retinal structure integrity.

RESULTS

Forty-five eyes of 39 subjects (PDT group-23 eyes, nMSL group-22 eyes) with chronic CSCR were analyzed. At 6 months' follow-up, the nMSL group had significantly higher improvement in visual acuity compared to the PDT group (0.12 ± 0.24 vs -0.02 ± 0.20 (p = 0.039)). Reduction in central macular thickness was significantly higher in nMSL group compared to the PDT (85.5 ± 93.26 vs 24.47 ± 73.18 microns (p = 0.02)). Thirteen (59%) eyes in nMSL group had complete resolution of the SRF at 6 months compared to 5 (21.7%) eyes in PDT group. There was no significant difference in rest of the anatomical features between the groups.

CONCLUSIONS

nMSL seems to be superior over PDT in improving visual and anatomical outcomes at 6 months and can be considered as a cheap alternative to PDT in treatment of CSCR.

Experimental verification of subthreshold laser therapy using conventional pattern scan laser

Purpose

Leading-edge therapeutic laser technologies are not available at every medical facility; therefore, alternative approaches incorporating novel advances in digital and laser technology into more readily available conventional methods have generated significant research interest. Using a rabbit model, this study investigated whether the algorithm used in the Endpoint Management (EM) software system of the latest devices could enable subthreshold laser treatment in conventional retinal tissue laser therapy systems.

Materials and methods

Two types of devices were used, the PASCAL Streamline 577 and the MC 500-Vixi™, and the laser method was classified into three categories: EM; single-shot using PASCAL with arbitrary energy settings (PSS-SDM); and MC500-Vixi^TM (VX-SDM), which were performed in eight eyes from four Dutch-Belted rabbits. In EM, 100 mW (100%) was set as a landmark, and the laser energy parameters were gradually decreased to 80%, 60%, 50%, 40%, 30%, 20%, and 10%, using a 2 × 3 square pattern. In PSS-SDM and VX-SDM, as control, the laser energy was gradually decreased to 100, 80, 60, 50, 40, 30, 20, and 10 mW. The laser settings were fixed at 200 μm, 20 ms, and a wavelength of 577 μm. To identify and compare the extent of tissue damage at each spot size, optical coherence tomography (OCT) and histological findings were used to construct a three-dimensional histopathology image using a confocal laser scanning fluorescence microscope.

Results

The spot size at 50% setting on EM was 7183 μm²; PSS-SDM required 50 mW (5503 μm²) to 60 mW (10279 μm²) and VX-SDM required 50 mW (7423 μm²) to create the approximate spot size. Furthermore, at 50 mW of PSS-SDM and VX-SDM, the extent of tissue damage in all three methods was generally in accord with the outer nuclear layer by OCT and inner nuclear layer by histopathological imaging.

Conclusion

These findings suggest that it may be possible to perform subthreshold laser therapy using approximations from the EM algorithm.

A Review of Subthreshold Micropulse Laser for Treatment of Macular Disorders

Micropulse laser treatment is an alternative to the conventional continuous-wave laser for the treatment of retinal or macular diseases. In contrast to the conventional laser, the therapeutic effect of the subthreshold micropulse laser is not accompanied by thermal retinal damage. This fact is of particular importance when a treatment near the fovea is required. Micropulse treatment is applied in indications such as central serous chorioretinopathy (CSC), diabetic macular edema (DME), or macular edema due to retinal vein occlusion (RVO). This review outlines and discusses the published literature of subthreshold micropulse laser treatment for CSC, DME, and macular edema after RVO.

Biological Modulation of Mouse RPE Cells in Response to Subthreshold Diode Micropulse Laser Treatment

Many clinical trials have demonstrated the effectiveness of subthreshold phototherapy with no visible damage in retinal vascular diseases, such as diabetic retinopathy. We aimed primarily to investigate the effect of subthreshold diode micropulse laser (SDM) treatment on mouse retinal pigmented epithelium (RPE) cells. The expression of angiogenesis-modulating cytokines in response to SDM was also explored. The least toxic laser dose was selected by measuring cell viability with MTT assay and 5 % duty cycle (DC) was chosen for use in further experiments. RPE cells were treated with laser-induced radiation ranging from 0 to 400 mW for 24 h. The apoptotic rate of RPE cells was assessed by flow cytometry. Expressions of vascular endothelial growth factor A (VEGF-A), transforming growth factor beta (TGF-β), basic fibroblast growth factor (bFGF), and pigment epithelium-derived factor (PEDF) were determined by Western Blotting and real-time PCR, respectively. After 24 h of laser irradiation, cell viability was reduced dose dependently and the effect was significant compared to the controls (P < 0.05). In addition, laser treatment with intensities of 100 and 200 mW with DC of 5 % produced no significant effect on cell viability and apoptosis as compared with the control group (P > 0.05). The protein and mRNA expressions of angiogenic stimulators (VEGF-A, TGF-β, and bFGF) were significantly down-regulated (P < 0.05), whereas those of the angiogenic inhibitor (PEDF) were up-regulated (P < 0.05). No significant difference was found between the cells treated with different intensities of laser radiation (P > 0.05). Our results showed that SDM treatment of the RPE cells suppressed the expression of choroid neovasculization-promoting cytokines and up-regulated the angiogenic inhibitor, PEDF without damaging the cells. Further investigation is needed to understand the mechanism and to optimize the use of SDM as a novel method of treatment for retinal vascular diseases.

Comparison of subthreshold diode laser micropulse therapy versus conventional photocoagulation laser therapy as primary treatment of diabetic macular edema

PURPOSE

The aim of the present study was to investigate the effect of subthreshold diode laser micropulse (SDM) in comparison with conventional laser photocoagulation in the treatment of the diabetic macular edema (DME).

METHODS

Sixty-eight eyes from 68 patients with clinically significant DME were divided randomly into two equal groups. In the first group, SDM photocoagulation was employed, while conventional laser photocoagulation was performed on the eyes of the second group. Central macular thickness (CMT), central macular volume (CMV), and best corrected visual acuity (BCVA) were measured before, 2, and 4 months after intervention, and the results were compared.

RESULTS

The mean CMT was 357.3 and 354.8 microns before the treatment in Groups 1 and 2, respectively (P = 0.85), and decreased significantly to 344.3 and 349.8 after 4 months, respectively (P = 0.012 and P = 0.049). The changes in the central macular thickness was statistically higher in the first group (P = 0.001). The mean CMV significantly decreased in Group 1 (P = 0.003), but it was similar to pretreatment in Group 2 after 4 months (P = 0.31). The BCVA improved significantly in Group 1 (P < 0.001), but it remained unchanged in Group 2 (P = 0.38).

CONCLUSIONS

In this study, SDM was more effective than conventional laser photocoagulation in reducing CMT and CMV and improving visual acuity in patients with DME.

Low-Fluence Photodynamic Therapy versus Subthreshold Micropulse Yellow Wavelength Laser in the Treatment of Chronic Central Serous Chorioretinopathy

Purpose. To compare the efficacy and safety of subthreshold micropulse yellow wavelength laser (SMYL) and low-fluence photodynamic therapy (PDT) in the treatment of chronic central serous chorioretinopathy (CSC). Methods. Thirty-three eyes of 30 patients with chronic CSC received either PDT (18 eyes) or SMYL (15 eyes) therapy. Best corrected visual acuity (BCVA), subretinal fluid (SRF) height, and central macular thickness (CMT) were evaluated at the baseline visit and one, three, six, nine, and 12 months after the therapy. Results. After 12 months, mean BCVA improved from 67.3 ± 14.2 to 71.5 ± 21.4 ETDRS letters in SMYL group and from 60.7 ± 16.3 to 64.4 ± 24.9 ETDRS letters in PDT group (p = 0.285 and p = 0.440, resp.). Mean CMT decreased from 242.8 ± 80 μm to 156.9 ± 60 μm in the PDT group and from 287.3 ± 126 μm to 138.0 ± 40 μm in the SMYL group (p = 0.098 and p = 0.003, resp.). SRF resolved completely in 72.2% and 80.0% of the eyes in the PDT and SMYL groups, respectively. Mean SRF height decreased from 117.2 ± 58 μm to 31.3 ± 56 μm in the PDT group and from 130.0 ± 104 μm to 12.5 ± 21 μm in the SMYL group (p = 0.031 and p = 0.014, resp.). Conclusions. Subthreshold micropulse yellow wavelength laser seems to be effective in the treatment of chronic CSC without any side effect and results in the resorption of SRF without causing visible retinal scarring.

Sub-threshold micro-pulse diode laser treatment in diabetic macular edema: A Meta-analysis of randomized controlled trials

AIM

To examine possible differences in clinical outcomes between sub-threshold micro-pulse diode laser photocoagulation (SDM) and traditional modified Early Treatment Diabetic Retinopathy Study (mETDRS) treatment protocol in diabetic macular edema (DME).

METHODS

A comprehensive literature search using the Cochrane Collaboration methodology to identify RCTs comparing SDM with mETDRS for DME. The participants were type I or type II diabetes mellitus with clinically significant macular edema treated by SDM from previously reported randomized controlled trials (RCTs). The primary outcome measures were the changes in the best corrected visual acuity (BCVA) and the central macular thickness (CMT) as measured by optical coherence tomography (OCT). The secondary outcomes were the contrast sensitivity and the damages of the retina.

RESULTS

Seven studies were identified and analyzed for comparing SDM (215 eyes) with mETDRS (210 eyes) for DME. There were no statistical differences in the BCVA after treatment between the SDM and mETDRS based on the follow-up: 3mo (MD, -0.02; 95% CI, -0.12 to 0.09; P=0.77), 6mo (MD, -0.02; 95% CI, -0.12 to 0.09; P=0.75), 12mo (MD, -0.05; 95% CI, -0.17 to 0.07; P=0.40). Likewise, there were no statistical differences in the CMT after treatment between the SDM and mETDRS in 3mo (MD, -9.92; 95% CI, -28.69 to 8.85; P=0.30), 6mo (MD, -11.37; 95% CI, -29.65 to 6.91; P=0.22), 12mo (MD, 8.44; 95% CI, -29.89 to 46.77; P=0.67). Three RCTs suggested that SDM laser results in good preservation of contrast sensitivity as mETDRS, in two different follow-up evaluations: 3mo (MD, 0.05; 95% CI, 0 to 0.09; P=0.04) and 6mo (MD, 0.02; 95% CI, -0.10 to 0.14; P=0.78). Two RCTs showed that the SDM laser treatment did less retinal damage than that mETDRS did (OR, 0.05; 95% CI, 0.02 to 0.13; P<0.01).

CONCLUSION

SDM laser photocoagulation shows an equally good effect on visual acuity, contrast sensitivity, and reduction of DME as compared to conventional mETDRS protocol with less retinal damage.

Short-pulse duration retinal lasers: a review

The development of lasers for biological use was an important medical advance in the 20th century with numerous evidence-based therapeutic applications to retinal disease, including capillary leakage at the macula. Although the role of photocoagulative laser in the treatment of macular oedema has diminished, there is evidence for a modified role in clinical management, particularly for extrafoveal leakage. Additionally, it may reduce the frequency of required intravitreal injections and assist in visual stabilization when used as an adjunct. The tissue destructive effect of photocoagulative lasers has motivated the development of safer macular lasers and the search for novel therapeutic applications, including treatment of drusen and regeneration of dysfunctional retinal pigment epithelium.

Sublethal Photothermal Stimulation with a Micropulse Laser Induces Heat Shock Protein Expression in ARPE-19 Cells

Purpose/Aim of the Study. Subthreshold micropulse diode laser photocoagulation is an effective treatment for macular edema. The molecular mechanisms underlying treatment success are poorly understood. Therefore, we investigated the effects of sublethal laser energy doses on a single layer of densely cultured ARPE-19 cells as a model of the human retinal pigment epithelium (RPE). Materials and Methods. A single layer of densely cultured human ARPE-19 cells was perpendicularly irradiated with a micropulse diode laser. Nonirradiated cells served as controls. Sublethal laser energy was applied to form a photocoagulation-like area in the cultured cell layers. Hsp70 expression was evaluated using quantitative polymerase chain reaction and immunocytochemistry. Results. Photocoagulation-like areas were successfully created in cultured ARPE-19 cell layers using sublethal laser energy with our laser irradiation system. Hsp70 mRNA expression in cell layers was induced within 30 min of laser irradiation, peaking at 3 h after irradiation. This increase was dependent on the number of laser pulses. Hsp70 upregulation was not observed in untreated cell layers. Immunostaining indicated that Hsp70 expression occurred concentrically around laser irradiation sites and persisted for 24 h following irradiation. Conclusion. Sublethal photothermal stimulation with a micropulse laser may facilitate Hsp70 expression in the RPE without inducing cellular damage.

Efficacy of Intravitreal Triamcinolone Acetonide for Diabetic Macular Edema After Vitrectomy

PURPOSE

To compare the efficacy of intravitreal injection of triamcinolone acetonide (IVTA) for diabetic macular edema (DME) in vitrectomized eyes with DME without vitrectomy eyes.

METHODS

This retrospective comparative study evaluated the efficacy of IVTA treatment of DME in 26 consecutive eyes (23 patients). Changes in mean best-corrected visual acuity (VA) and mean central retinal thickness (CRT) were retrospectively evaluated before IVTA and during the 6-month period after IVTA.

RESULTS

Subjects were divided into 2 groups: 13 consecutive eyes (11 patients) with proliferative diabetic retinopathy or DME that underwent vitrectomy (vitrectomized group), and 13 consecutive eyes (12 patients) with DME who received IVTA, but did not undergo vitrectomy (nonvitrectomized group). In the vitrectomized group, there was a significantly decreased CRT for up to 4 months as compared to the thicknesses before IVTA. In the nonvitrectomized group, there was a significantly decreased CRT for up to 5 months after IVTA. In both groups, there was significant improvement in the VA for up to 4 months after IVTA.

CONCLUSION

IVTA may represent a valid treatment option for DME, even in vitrectomized eyes.

Prognosis of patients with diabetic macular edema before Japanese approval of anti-vascular endothelial growth factor

PURPOSE

To examine the prognosis of patients with diabetic macular edema (DME) before Japanese approval of antivascular endothelial growth factor (VEGF).

METHODS

This retrospective study included 135 eyes of 115 patients who received treatments (photocoagulation, pharmacological treatments, vitrectomy) for DME between January 2003 and August 2012. The best-corrected visual acuity (BCVA) before and 1, 3, 6, 12, and 24 months after treatment was examined. BCVA was classified based on the decimal value of BCVA before treatment as good (BCVA > 0.7, BCVA = 0.7), moderate (BCVA > 0.7 but <0.2), or poor (BCVA < 0.2, BCVA = 0.2), and each prognosis of BCVA was investigated.

RESULTS

Thirty-five (25.9%) patients were classified with good BCVA, while 69 (51.1%) had moderate and 31 (23.0%) poor BCVA. Following 24 months of treatment, the averaged good BCVA maintained its value (0.0513 ± 0.0954 to 0.0773 ± 0.258). Similarly, the averaged moderate BCVA maintained its value (0.449 ± 0.169 to 0.441 ± 0.431), whereas the averaged poor BCVA significantly improved (1.070 ± 0.291 to 0.879 ± 0.361: p < 0.001). Specifically, the averaged BCVA of patients who initially received vitrectomy increased 0.380 logMAR after 24 months (0.859 ± 0.414 to 0.479 ± 0.549).

CONCLUSION

DME patients with good BCVA at the time of initial treatment generally maintained the averaged BCVA at 24 months, while patients with moderate BCVA did not significantly improve without a standard regimen of anti-VEGF therapy. However, the results indicate that early vitrectomy is a potential treatment option for DME patients with poor BCVA.

Recent Innovations in Medical and Surgical Retina

PURPOSE

To summarize major innovations in retinal disease management during fiscal year 2014.

DESIGN

Literature review.

METHODS

A subset of papers published in the peer-reviewed literature were selected.

RESULTS

Major innovations in retina include: (1) advances in the treatment of diabetic macular edema, including the use of aflibercept and sustained delivery dexamethasone intravitreal implants as well as subthreshold micropulse diode laser therapy; (2) reduced progression of age-related macular degeneration (AMD) using zinc, vitamin C, vitamin E, lutein, and zeaxanthin supplements as reported in the Age-Related Eye Disease Study-2; (3) use of enhanced-depth imaging optical coherence tomography for choroidal imaging; (4) use of gene therapy to treat choroideremia; (5) use of combination pharmacotherapy (i.e., squalamine + ranibizumab) and gene therapy to treat the neovascular complications of AMD; and (6) use of stem cell-derived retinal pigment epithelium transplants to treat atrophic AMD and Stargardt macular dystrophy. In addition, we review the ocular and systemic risks associated with sustained intraocular steroid delivery and inhibition of vascular endothelial growth factor signaling pathways. We also review potential applications of gene- versus cell-based therapy for the treatment of retinal degenerative diseases.

CONCLUSIONS

Several treatment approaches are effective in the treatment of diabetic macular edema. Prophylaxis against AMD progression with Age-Related Eye Disease Study-2 supplements seems to reduce the risk of developing neovascular but not atrophic complications of AMD. Enhanced-depth imaging optical coherence tomography data provide new information on the role of the choroid in a variety of conditions. Advances in gene- and cell-based therapy will revolutionize the development of regenerative medicine in ophthalmology.

Treatment of diabetic maculopathy

Diabetic maculopathy is an important cause of severe sight impairment. There has been a significant evolution in its treatment over the past decade and laser treatment is now largely being superseded by intravitreal injections of anti-vascular endothelial growth factor agents or corticosteroids.

Randomised clinical trial evaluating best-corrected visual acuity and central macular thickness after 532-nm subthreshold laser grid photocoagulation treatment in diabetic macular oedema

Purpose

To compare best-corrected visual acuity (BCVA) and central macular thickness (CMT) after 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation for the treatment of diabetic macular oedema (DME).

Patients and methods

Twenty-three patients (46 eyes) with binocular DME were enroled in this study. The two eyes of each patient were divided into a subthreshold photocoagulation group and a threshold photocoagulation group. The eyes of the subthreshold group underwent 532-nm patter scan laser system (PASCAL) 50% end point subthreshold laser grid photocoagulation therapy, whereas the threshold photocoagulation group underwent short-pulse grid photocoagulation with a 532-nm PASCAL system. BCVA and CMT were assessed in all patients before treatment, 7 days after treatment, and 1, 3, and 6 months after treatment.

Results

After grid photocoagulation, the mean BCVA improved in both the subthreshold group, and the threshold group, and the two groups did not differ statistically significantly from each other. Similarly, the macular oedema diminished in both groups after treatment, and the two groups did not differ statistically significantly from each other with regard to CMT.

Conclusion

Both 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation can improve the visual acuity and reduce CMT in DME patients.

Comparative efficacy of pure yellow (577-nm) and 810-nm subthreshold micropulse laser photocoagulation combined with yellow (561-577-nm) direct photocoagulation for diabetic macular edema

PURPOSE

To compare the efficacy of 577- and 810-nm subthreshold micropulse laser photocoagulation (SMLP) combined with direct photocoagulation to microaneurysms in diabetic macular edema (DME).

METHODS

A prospective nonrandomized interventional case series. Forty-nine consecutive patients (53 eyes) with DME were recruited. In 20/24 (83.3%) eyes, 810-nm SMLP (810-nm MP) to achieve a confluent grid pattern was followed by direct photocoagulation to microaneurysms via a continuous 561-nm wavelength laser. In 21/29 (72.5%) eyes, 577-nm SMLP (577-nm MP) was combined with direct photocoagulation to microaneurysms via the same instrument. Best-corrected visual acuity (BCVA) and central macular thickness (CMT) were examined 1, 2, 3, 6 and 12 months after treatment.

RESULTS

The mean power required for SMLP was lower in the 577-nm than in the 810-nm MP group (204.1 vs. 954.1 mW) (p < 0.0001). Significant reductions in CMT persisted from 3 to 12 months after treatment in all patients (p < 0.01). There were no significant intergroup differences in CMT until 12 months. In both groups, mean BCVA remained stable until 12 months after treatment. Additional treatment for persistent macular edema was performed within 12 months in 4/24 eyes (16.7%) in the 810-nm MP group and 1/29 eyes (3.4%) in the 577-nm MP group.

CONCLUSION

Either 577-nm MP or 810-nm MP combined with direct photocoagulation for microaneurysm closure reduced DME, maintained visual acuity and reduced the additional treatment rate within 12 months. The 577-nm MP apparatus required less energy for SMLP than the 810-nm MP instrument and was suitable for direct photocoagulation of microaneurysms.

The short-term efficacy of subthreshold Micropulse yellow (577-nm) laser photocoagulation for diabetic macular edema

Purpose

This pilot study aimed to evaluate the efficacy and safety of subthreshold micropulse yellow (577-nm) laser photocoagulation (SMYLP) in the treatment of diabetic macular edema (DME).

Methods

We reviewed 14 eyes of 12 patients with DME who underwent SMYLP with a 15% duty cycle at an energy level immediately below that of the test burn. The laser exposure time was 20 ms and the spot diameter was 100 µm. Laser pulses were administered in a confluent, repetitive manner with a 3 × 3 pattern mode.

Results

The mean follow-up time was 7.9 ± 1.6 months. The baseline-corrected visual acuity was 0.51 ± 0.42 logarithm of the minimum angle of resolution (logMAR), which was improved to 0.40 ± 0.35 logMAR (p = 0.025) at the final follow-up. The central macular thickness at baseline was 385.0 ± 111.0 µm; this value changed to 327.0 ± 87.7 µm (p = 0.055) at the final follow-up.

Conclusions

SMYLP showed short-term efficacy in the treatment of DME and did not result in retinal damage. However, prospective, comparative studies are needed to better evaluate the efficacy and safety of this treatment.

Subthreshold Micropulse Photocoagulation for Persistent Macular Edema Secondary to Branch Retinal Vein Occlusion including Best-Corrected Visual Acuity Greater Than 20/40

To assess the efficacy of subthreshold micropulse diode laser photocoagulation (SMDLP) for persistent macular edema secondary to branch retinal vein occlusion (BRVO), including best-corrected visual acuity (BCVA) > 20/40, thirty-two patients (32 eyes) with macular edema secondary to BRVO were treated by SMDLP. After disease onset, all patients had been followed for at least 6 months prior to treatment. Baseline Snellen visual acuity was used to categorize the eyes as BCVA ≤ 20/40 (Group I) or BCVA > 20/40 (Group II). Main outcome measures were reduction in central macular thickness (CMT) in optical coherence tomography (OCT) and BCVA at 6 months. In the total subject-pool at 6 months, BCVA had not changed significantly but CMT was significantly reduced. Group I exhibited no significant change in CMT at 3 months but exhibited significant reductions at 6 and 12 months. Group II exhibited a marginally significant reduction in CMT at 3 months and a significant reduction at 6 months. In patients with persistent macular edema secondary to BRVO, SMDLP appears to control macular edema with minimal retinal damage. Our findings suggest that SMDLP is an effective treatment method for macular edema in BRVO patients with BCVA > 20/40.

Recent developments in retinal lasers and delivery systems

Photocoagulation is the standard of care for several ocular disorders and in particular retinal conditions. Technology has offered us newer lasing mediums, wavelengths and delivery systems. Pattern scan laser in proliferative diabetic retinopathy and diabetic macular edema allows laser treatment that is less time consuming and less painful. Now, it is possible to deliver a subthreshold micropulse laser that is above the threshold of biochemical effect but below the threshold of a visible, destructive lesion thereby preventing collateral damage. The advent of solid-state diode yellow laser allows us to treat closer to the fovea, is more effective for vascular structures and offers a more uniform effect in patients with light or irregular fundus pigmentation. Newer retinal photocoagulation options along with their advantages is discussed in this review.

Diabetic macular edema: new concepts in patho-physiology and treatment

Diabetic macular edema (DME), a serious eye complication caused primarily by hyperglycemia, is one of the major causes of blindness. DME, which is characterized by cystic retinal thickening or lipid deposition, is prone to relapse after successful treatment. DME is a complex pathological process caused by multiple factors, including breakdown of the inner and outer blood-retinal barriers, oxidative stress, and elevated levels of vascular endothelial growth factor which have been demonstrated in both preclinical and clinical studies. Starling's law theory explains many of the features of DME. Early detection and treatment of DME can prevent vision loss. Current effective interventions for DME include treatment of systemic risk factors, such as elevated blood glucose, blood pressure and dyslipidemia. Ophthalmic treatments include laser photocoagulation, surgery and intraocular pharmacotherapy. New drugs, which are given by intraocular injection, have emerged in recent years to become first line treatment for DME that affects the central macula with loss of vision. Laser photocoagulation is still the gold standard of treatment for DME which does not involve the central macular. This review outlines these new treatments with particular emphasis on the optimal timing of how they are given.

Evolving strategies in the management of diabetic retinopathy

Diabetic retinopathy (DR), the most common long-term complication of diabetes mellitus, remains one of the leading causes of blindness worldwide. Tight glycemic and blood pressure control has been shown to significantly decrease the risk of development as well as the progression of retinopathy and represents the cornerstone of medical management of DR. The two most threatening complications of DR are diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR). Focal/grid photocoagulation and panretinal photocoagulation are standard treatments for both DME and PDR, respectively. Focal/grid photocoagulation is a better treatment than intravitreal triamcinolone acetonide in eyes with DME. Currently, most experts consider combination focal/grid laser therapy and pharmacotherapy with intravitreal antivascular endothelial growth factor agents in patients with center-involving DME. Combination therapy reduces the frequency of injections needed to control edema. Vitrectomy with removal of the posterior hyaloid seems to be effective in eyes with persistent diffuse DME, particularly in eyes with associated vitreomacular traction. Emerging therapies include fenofibrate, ruboxistaurin, renin-angiotensin system blockers, peroxisome proliferator-activated receptor gamma agonists, pharmacologic vitreolysis, and islet cell transplantation.