Subthreshold Diode Micropulse Laser Combined with Intravitreal Therapy for Macular Edema-A Systematized Review and Critical Approach

Photobiomodulation for diabetes and its complications: a review of general presentation, mechanisms and efficacy

Diabetes mellitus is a metabolic disease that is marked by persistent hyperglycemia due to inadequate insulin secretion or insulin resistance. Its prevalence is increasing yearly. Diabetes mellitus can lead to serious health complications that are the primary cause of mortality and disability among diabetic patients, including diabetic retinopathy, diabetic foot ulcers, diabetic peripheral neuropathy, and diabetic periodontitis, and so on. Traditional treatments for diabetes and its complications still suffer from limited clinical efficacy and high therapeutic side effects. Photobiomodulation (PBM), which utilizes low levels of red or near-infrared laser to irradiate cells and tissues, has been shown to be efficacious for a wide range of organ damage. In this study, we focus on the application of PBM in diabetes and its complications and mechanisms, as well as the advantages, disadvantages with the aim of developing new ideas for the application of PBM.

Optimizing Diabetic Macular Edema Treatment: A Meta-Analysis of Subthreshold Micropulse Laser and Anti-Vascular Endothelial Growth Factor Combination Therapy

Background: Diabetic macular edema (DME) is the primary cause of visual impairment in individuals with diabetes. Anti-vascular endothelial growth factor (VEGF) is the current first-line treatment for DME owing to its effectiveness. However, frequent anti-VEGF injections may be inconvenient for patients. Therefore, this study aimed to investigate whether the addition of subthreshold micropulse laser (SML) to anti-VEGF therapy could reduce the requirement for anti-VEGF injections while maintaining the treatment efficacy for DME. Methods: Clinical trials retrieved from the databases of PubMed, EMBASE, and the Cochrane Library were evaluated to determine the effectiveness of combination treatment with SML and anti-VEGF medication compared with that of anti-VEGF treatment alone. The primary outcome measures were the changes in CMT, best-corrected visual acuity (BCVA), and the total number of intravitreal injections (IVIs). Results: The IVI + SML group revealed a substantial increase in the logarithm of the minimum angle of the resolution BCVA and a reduction in CMT at the 12-month follow-up (BCVA: random-effects; mean difference [MD], -0.05; 95% confidence interval [CI]: -0.10 to -0.01; p-value = 0.28, and CMT: random-effects; MD, -18.27; 95% confidence interval, -27.36 to -9.18; p-value = 0.20). The number of required IVIs in the IVI + SML group was lower than that in the IVI only group (random-effects; MD, -2.22; 95% CI: -3.13 to -1.31; p-value < 0.01). Conclusions: Combining SML therapy with anti-VEGF injections may reduce the total number of injections required, improve VA, and reduce CMT at the 12-month follow-up. Although the included studies used different SML regimens and anti-VEGF agents, this review indicates that the application of additional SML therapy results in positive clinical outcomes.

Retinal Vein Occlusion-Background Knowledge and Foreground Knowledge Prospects-A Review

Thrombosis of retinal veins is one of the most common retinal vascular diseases that may lead to vascular blindness. The latest epidemiological data leave no illusions that the burden on the healthcare system, as impacted by patients with this diagnosis, will increase worldwide. This obliges scientists to search for new therapeutic and diagnostic options. In the 21st century, there has been tremendous progress in retinal imaging techniques, which has facilitated a better understanding of the mechanisms related to the development of retinal vein occlusion (RVO) and its complications, and consequently has enabled the introduction of new treatment methods. Moreover, artificial intelligence (AI) is likely to assist in selecting the best treatment option for patients in the near future. The aim of this comprehensive review is to re-evaluate the old but still relevant data on the RVO and confront them with new studies. The paper will provide a detailed overview of diagnosis, current treatment, prevention, and future therapeutic possibilities regarding RVO, as well as clarifying the mechanism of macular edema in this disease entity.

Subthreshold laser treatment in retinal diseases: a mini review

PURPOSE

To summarize the mechanism and the clinical applications of subthreshold laser (STL) in retinal practice. Subthreshold or "non-destructive" laser includes all types of laser treatments that produce minimal or no damage to the tissues and no visible signs after application.

METHODS

A descriptive review of articles from literature databases (PubMed, Medline, Embase, Cochrane, Web of Science) published before August 2023, which discuss current STL treatments of retinal diseases.

RESULTS

This review provides evidence for STL as a treatment option for central serous chorioretinopathy, diabetic retinopathy, age-related macular degeneration, macular edema due to retinal vein occlusion, and other maculopathies. In most published reports, STL has shown a therapeutic effect without damage to the underlying tissue.

CONCLUSION

Subthreshold laser treatment has shown safety and efficacy in the management of some retinal and macular diseases. Stimulation of the retinal pigment epithelium without destroying adjacent neuroretina has been shown to be sufficient in inducing retinal repair in many clinical cases. Recent research and clinical studies continue to explore the mechanisms and improving therapeutic benefits of this technology as well as extend the range of retinal disorders treatable by this modality.

Subthreshold micropulse diode laser treatment in diabetic macular edema: biological impact, therapeutic effects, and safety

PURPOSE

To introduce the treatment of diabetic macular edema (DME) with subthreshold micropulse diode laser (SMPL), to summarize the biological impact, therapeutic effects, and safety of this treatment, and to discuss the response to DME when SMPL is combined with anti-vascular endothelial growth factor (anti-VEGF) or steroid.

METHODS

The literature search was performed on the PubMed database, with a selection of English-language articles published from 2000 to 2023 with the following combinations of search terms: diabetes macular (o) edema, micropulse laser or subthreshold micropulse laser, anti-vascular endothelial growth factor, and steroid.

RESULTS

SMPL is a popular, invisible retinal laser phototherapy that is inexpensive, safe, and effective in the treatment of DME. It can selectively target the retinal pigment epithelium, reduce the expression of pro-inflammatory factors, promote the absorption of macular edema, and exert a similar and lasting clinical effect to traditional lasers. No significant difference was found in the therapeutic effects of SMPL between different wavelengths. However, HbA1c level and pretreatment central macular thickness (CMT) may affect the therapeutic outcomes of SMPL.

CONCLUSION

SMPL has a slow onset and produces lasting clinical effects similar to conventional photocoagulation. It has been reported that SMPL combined with the intravitreal anti-VEGF injection can significantly reduce the number of injections without influencing the therapeutic effect, which is essential for clinical applications and research. Although 577 nm SMPL is widely used clinically, there are no standardized protocols for SMPL. Additionally, some important problems regarding the treatment of SMPL require further discussion and exploration.

Crossover to PDT after the unsuccessful micropulse laser treatment of central serous chorioretinopathy

Purpose

Subthreshold micropulse laser (SML) and photodynamic therapy (PDT) are among the most effective therapeutic modalities applied to central serous chorioretinopathy (CSCR). This study aimed to evaluate the efficacy and durability of PDT in CSCR cases unresponsive to at least two SML treatments.

Methods

The study included 26 consecutive eyes of 24 patients (21 males and three females) with chronic CSCR. In all cases, a lack of reduction in subretinal fluid (SRF) levels was noted after at least two consecutive SML sessions. The parameters of best corrected visual acuity (BCVA) and spectral domain optical coherence tomography (SD-OCT) were evaluated at baseline and 1, 3 and 12 months post-PDT.

Results

The mean duration of symptoms in the group was 53.81 ± 39.48 months, the mean age of the patients was 49.26 ± 12.91 years, and the mean subfoveal choroidal thickness (SFCT) was 572.11 ± 116.21 mm. Complete resorption of SRF was observed in 21 out of 26 eyes (80.77%) at 1 month and sustained in 18 cases (69.23%) at 12 months. At 12 months, in the sustained group, BCVA improved significantly from 0.39 ± 0.18 to 0.19 ± 0.2 logMAR (P = 0.01), central subfoveal thickness (CST) reduced from 316.44 ± 75.83 mm to 197.67 ± 22.99 mm (P < 0.0001), and SFCT reduced from 579.28 mm to 446.78 mm (P < 0.0001).

Conclusions

PDT provides the opportunity for the successful treatment of CSCR unresponsive to SML treatment. Improvements are possible even in cases with a long duration of symptoms and significant alterations in retinal morphology. Thus, PDT should be considered for patients with prominently increased choroidal thickness.

Adjunct Nondamaging Focal Laser Reduces Intravitreal Injection Burden in Diabetic Macular Edema

This study aims to determine the impact of adjunct nondamaging focal laser therapy on the number of anti-vascular endothelial growth factor (anti-VEGF) injections and visual acuity (VA) and imaging in patients with diabetic macular edema (DME). A retrospective analysis of 18 eyes of 14 patients with DME treated with a single session of the PASCAL 532 nm Synthesis Photocoagulator with Endpoint Management was conducted. Demographic data, VA, imaging, laser parameters, and anti-VEGF injection burden six months before and after treatment were collected. Wilcoxon Signed-rank tests were used to assess changes in VA and injection burden before and after treatment. The mean number of intravitreal injections in the six-month period prior to laser treatment was 3.39 ± 2.57 injections compared to 2.33 ± 2.40 injections following laser treatment (p = 0.02). There was no significant difference between the mean VA on the day of treatment logMAR VA of 0.38 ± 0.27 (approx. Snellen equivalent 20/50) and the visual acuity on the most recent follow-up 6 months after laser logMAR VA of 0.35 ± 0.32 (approx. Snellen equivalent 20/40) (p = 0.34). There was also no significant difference in OCT central macular thickness before (311 μm) compared to 6 months after (301 μm, p = 0.64). Adjunct focal macular laser therapy is associated with a statistically and clinically significant decrease in the number of intravitreal injections required in the six-month period immediately following treatment, without compromising visual acuity or macular thickness. Nondamaging focal laser has the potential to alleviate the burden of injections for both patients and clinics.

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

OBJECTIVE

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).

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Micropulse Laser Therapy as an Integral Part of Eye Disease Management

Ocular diseases can significantly impact vision and quality of life through pathophysiological alterations to the structure of the eye. The management of these conditions often involves a combination of pharmaceutical interventions, surgical procedures, and laser therapy. Laser technology has revolutionized many medical fields, including ophthalmology, offering precise and targeted treatment options that solve some of the unmet needs of other therapeutic strategies. Conventional laser techniques, while effective, can generate excessive thermal energy, leading to collateral tissue damage and potential side effects. Compared to conventional laser techniques, micropulse laser therapy delivers laser energy in a pulsed manner, minimizing collateral damage while effectively treating target tissues. The present paper highlights the advantages of micropulse laser therapy over conventional laser treatments, presents the implications of applying these strategies to some of the most prevalent ocular diseases, and highlights several types and mechanisms of micropulse lasers. Although micropulse laser therapy shows great potential in the management of ocular diseases, further research is needed to optimize treatment protocols, evaluate long-term efficacy, and explore its role in combination therapies.

Comparative Treatment Study on Macular Edema Secondary to Branch Retinal Vein Occlusion by Intravitreal Ranibizumab with and without Selective Retina Therapy

The purpose of this study was to compare the safety and efficacy of selective retina therapy (SRT) combined with the intravitreal injection of ranibizumab (IVR) in patients with macular edema (ME) secondary to branch retinal vein occlusion (BRVO). This trial was a 12-month single-center, randomized, single-masked prospective study. Eligible patients were randomized (1:1) to IVR and SRT (IVR + SRT group), or IVR and sham SRT (IVR + sham group). After the initial IVR, all participants received ME resolution criteria-driven pro re nata treatment. SRT or sham SRT was always applied one day after IVR. The primary outcome measure of this study was the mean change in central macular thickness (CMT) from baseline, and the secondary outcome measures were the mean change in visual acuity from baseline and the number of IVR treatments at a 52-week follow-up. Thirteen patients were in the IVR + SRT group, and 11 were in the IVR + sham group. Compared to the baseline, mean CMT and BCVA improved significantly after 52 weeks in both groups, with no significant difference between the two groups. The mean number of IVR was 2.85 ± 1.52 in the IVR + SRT group and 4.73 ± 2.33 in the IVR + sham group at the 52-week follow-up, with a significant difference between the two groups (p < 0.05). IVR combined with SRT may significantly decrease the number of IVR treatments while maintaining the visual and anatomical improvement effect of IVR monotherapy.

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.

Intravitreal Dexamethasone Implant (IDI) Alone and Combined with Navigated 577 nm Subthreshold Micropulse Laser (SML) for Diabetic Macular Oedema

Background: The anatomical and functional changes after intravitreal dexamethasone implant (IDI) alone and combined with navigated subthreshold micropulse laser (NSML) in diabetic macular oedema (DMO) were compared. Methods: Patients with a clinically confirmed diagnosis of non-proliferative diabetic retinopathy (NPDR) and DMO were enrolled in this prospective study and were randomly assigned to two different treatment groups: thirty patients were treated with IDI (IDI group), and the other 30 patients received IDI combined with NSML treatment (combined IDI/NSML group). All patients during a 6-month follow-up underwent best corrected visual acuity (BCVA) evaluation and spectral domain optical coherence tomography (SD OCT). The main outcome measures were: BCVA, central macular thickness (CMT); (3) choroidal vascularity index (CVI), subfoveal choroidal thickness (SCHT); and time to retreatment between IDI at baseline and the second implant in both groups. Results: BCVA, CMT, and SCHT significantly decreased starting from the 1-month follow-up and CVI from 3 months in both groups. The between-group differences were significantly different from 1-month follow-up for BCVA, from 5-month follow-up for CMT and SCHT, and from 4-month follow-up for CVI. The Needed to Treat analysis indicated that six patients would have to be treated with SML after IDI in order for just one person to receive a benefit. Conclusions: the combined treatment showed good anatomical and functional outcomes for the treatment of DMO. In addition, IDI/SML seems to reduce injection frequency over time, improving patients’ quality of life and reducing the socio-economic burden.

Modified Microneedle for Suprachoroidal Injection of Triamcinolone Acetonide Combined with Intravitreal Injection of Ranibizumab in Branch Retinal Vein Occlusion Patients

Purpose

The present study evaluated the efficacy of combined suprachoroidal injection of triamcinolone acetonide (TA) using a modified microneedle with intravitreal injection of ranibizumab in branch retinal vein occlusion (BRVO) patients.

Patients and methods

This is a prospective randomised interventional study that was conducted on 60 eyes of 60 patients with non ischemic BRVO. Patients were divided in two groups, group (1) 30 patients who received intravitreal injection of 0.05 mL (0.5 mg) of ranibizumab, group (2) included 30 patients who received baseline combined intravitreal injection of 0.05 mL (0.5 mg) of ranibizumab and suprachoroidal injection of triamcinolone acetonide (4mg/0.1mL), both groups received monthly injection of ranibizumab on pro-re-nata (PRN) regimen for 1 year duration of the study.

Results

Group 2 received less number of injections (2.47 ± 1.2) as compared to group 1 (4.4 ± 1.5). Both groups achieved significant reduction of central macular thickness (CMT) after 12 months of injection with p value <0.001. Both groups showed significant improvement of best corrected visual acuity (BCVA) after 12 months with p value <0.001. Group 2 showed more significant improvement of BCVA after 6 and 12 months. The baseline CMT and the number of injections were the main predictors of the final BCVA in group 1, while the baseline BCVA was the only predictor of final BCVA in group 2.

Conclusion

Combined suprachoroidal injection of TA using this modified microneedle with intravitreal injection of ranibizumab resulted in more significant improvement of BCVA and reduction of CMT compared with ranibizumab monotherapy with no reported ocular or systemic side effects. The study was prospectively registered with clinical trial.gov ID (NCT04690608) in 27-12-2020.

Treatment of Macular Edema in Vascular Retinal Diseases: A 2021 Update

Macular edema (ME) is associated with various conditions; however, the main causes of ME are retinal vein occlusion (RVO) and diabetes. Laser photocoagulation, formerly the gold standard for the treatment of ME, has been replaced by anti-vascular endothelial growth factor (anti-VEGF) intravitreal injections. Despite its efficiency, this treatment requires frequent injections to preserve the outcomes of anti-VEGF therapy, and as many patients do not sufficiently respond to the treatment, ME is typically a chronic condition that can lead to permanent visual impairment. Generalized recommendations for the treatment of ME are lacking, which highlights the importance of reviewing treatment approaches, including recent anti-VEGFs, intravitreal steroid implants, and subthreshold micropulse lasers. We reviewed relevant studies, emphasizing the articles published between 2019 and 2021 and using the following keywords: macular edema, diabetic macular edema, retinal vein occlusion, laser photocoagulation, anti-VEGF, and intravitreal injections. Our results revealed that a combination of different treatment methods may be beneficial in resistant cases. Additionally, artificial intelligence (AI) is likely to help select the best treatment option for patients in the near future.

Subthreshold micropulse laser adjuvant to bevacizumab versus bevacizumab monotherapy in treating diabetic macular edema: one- year- follow-up

Purpose

To compare the therapeutic impact of combining intravitreal injections of bevacizumab (IVB) with micropulse laser (MPL) in central diffuse diabetic macular edema (DME) versus IVB monotherapy during 12 months follow-up.

Methods

We conducted a retrospective comparative study of 98 treatment-naive eyes (63 patients) with central diffuse DME. The first group of patients (IVB + MPL group, n = 49) was treated with 3 monthly IVB followed by MPL within 1 week after the third injection. Patients were then followed and treated on a pro re nata (PRN) basis, with MPL retreatment if necessary. The changes in best-corrected visual acuity (BCVA), central macular thickness (CMT), number of IVB injections and MPL sessions were evaluated at 4, 8, and 12 months. A control group of diabetic patients with treatment-naive DME was treated with standard protocol of 3 monthly IVB as monotherapy then followed on a PRN basis (IVB group, n = 49). Statistic comparaison of BCVA, CMT, and IVB number variation was interpreted at 12 months between both groups.

Results

In IVB + MPL group, baseline BCVA improvement was not significant at 4 and 8 months (p = 0.90, p = 0.08), and was statistically significant (p = 0.01) at 12 months. Mean CMT significantly decreased at 4, 8, and 12 months (p < 0.01) in IVB + MPL group. The difference in BCVA (p = 0.091) and CMT (p = 0.082) variation at 12 months between both groups was not significant but the number of injections was significantly lower in IVB + MPL group (4.1 ± 1.5 injections) compared to IVB group (7.2 ± 1.3 injections) (p < 0.005).

Conclusion

Combining intravitreal injections of bevacizumab and MPL in the treatment of DME is effective and safe. This protocol may decrease the number of IVB and its frequency. It offers the advantage of lasting therapeutic response with fewer recurrences.

Laser Therapy in the Treatment of Diabetic Retinopathy and Diabetic Macular Edema

PURPOSE OF REVIEW

This review highlights indications and evidence on laser therapy in the management of diabetic retinopathy and diabetic macular edema. Particular focus is placed upon the benefits and limitations of conventional laser photocoagulation versus more modern laser photocoagulation techniques, as well as the role of laser photocoagulation in treatment of diabetic retinopathy and diabetic macular edema with the frequent utilization of pharmacologic, including anti-vascular endothelial growth factor (VEGF), therapy.

RECENT FINDINGS

Laser photocoagulation remains the gold-standard therapy for the effective, definitive treatment of PDR, and also is highly effective in the management of DME. However, numerous recent studies have demonstrated the clinical efficacy and improved functional and anatomic outcomes of combination therapy with pharmacologic treatment. Continuing innovations in laser technology and improved understanding of laser-retinal interactions and pathophysiology demonstrate that laser therapy will continue to play a critical role in the treatment of diabetic retinopathy and diabetic macular edema for many years to come.