Subthreshold micropulse laser versus intravitreal anti-VEGF for diabetic macular edema patients with relatively better visual acuity

Six-month results of 577 nm subthreshold micropulse laser therapy in non-center involving diabetic macular edema

BACKGROUND

This study aimed to evaluate the efficacy of 577 nm subthreshold micropulse laser (SML) therapy in patients with non-center involving diabetic macular edema (DME).

METHODS

Twenty-two eyes of 18 patients diagnosed with non-center involving DME were included in this prospective, observational study. The patient's baseline best corrected visual acuity (BCVA), maximum retinal thickness (MRT), central macular thickness (CMT), and the area of macular exudates were determined and re-evaluated at 1, 3, and 6 months after laser treatment.

RESULTS

There was no statistically significant change in BCVA at the 1st, 3rd and 6th months compared to the baseline in the follow-up (p = 0.067, p = 0.270, p = 0.027 according to Bonferroni correction p < 0,01). 1st, 3rd, and 6th month MRT was statistically significantly lower than baseline (p = 0,009, p = 0,006, p = 0,007). No statistically significant change was detected in CMT at the 1st, 3rd and 6th months compared to the baseline in the follow-up (p = 0.384, p = 0.794, p = 0.363). No statistically significant change in the area of macular exudates was detected at the 1st, 3rd, and 6th months compared to the baseline (p = 0.904, p = 0.444, p = 0.277).

CONCLUSIONS

This study observed a significant decrease in extrafoveal retinal thickness in patients with DME. There was no progression to central macular involvement, an increase in the area of exudates, and a decrease in BCVA in any patient. SML may be an effective alternative to conventional argon laser in non-center involving DME.

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.

Yellow Subthreshold Micropulse Laser in Retinal Diseases: An In-Depth Analysis and Review of the Literature

Yellow subthreshold micropulse laser (YSML) is a retinal laser capable of inducing a biologic response without causing thermal damage to the targeted tissue. The 577-nm YSML is delivered to the retina abiding by different protocols in which wavelength, power, duration, spot size and number of spots can be properly set to achieve the most effective and safe treatment response in various chorioretinal disorders. The ultrashort trains of power modulate the activation of the retinal pigment epithelium cells and intraretinal cells, such as Müller cells, causing no visible retinal scars. Subthreshold energy delivered by YSML stimulates the production of the heat-shock proteins, highly conserved molecules that protect cells against any sort of stress by blocking apoptotic and inflammatory pathways that cause cell damage. YSML treatment allows resorption of the subretinal fluid in central serous chorioretinopathy and intraretinal fluid in various conditions including diabetic macular edema, postoperative cystoid macular edema and other miscellaneous conditions. YSML also seems to modulate the development and progression of reticular pseudodrusen in dry age-related macular degeneration. The aim of this review is to discuss and summarize the safety and efficacy of YSML treatment in retinal diseases.

Diabetic macular edema treatment with subthreshold micropulse laser - five-year long monitoring

AIM

The objective of this study was to evaluate the efficacy of diabetic macular edema (DME) therapy using subthreshold micropulse laser (SMPL) with a wavelength of 577 nm during a long-term monitoring period of 5 years.

METHODS

The cohort included the total number of 52 eyes of 34 patients with DME. All underwent the standard laser treatment for the diabetic retinopathy outside the macula and DME treatment with SMPL. Subsequent check-ups were followed every 3 months in the first year of treatment, and every 4 to 6 months in the following years. The treatment was combined neither with focal macular laser nor with anti-VEGF therapy.

RESULTS

The mean central retinal thickness (CRT) was 345.9 µm SD 122.6 µm at the beginning of the monitoring. At the end of the follow-up period five years after treatment it was 256.4 µm SD 98.4 µm. The mean CRT decreased by 89.5 µm SD 153.6 µm during 5 years. At the beginning of the monitoring, before treatment with SMPL, the best corrected visual acuity (BCVA) was 70.0, SD 10.1 ETDRS letters. One year after therapy, BCVA was 72, SD 10.0 letters, two years later it was 71.4, SD 10.4 letters and decreased to 66.9, SD 12.1 letters after 5 years. The mean BCVA decreased by merely 3.1, SD 10.9 letters during 5 years.

CONCLUSION

Based on our long-term observations, the DME treatment with SMPL appears to be an effective method for reducing DME and protecting BCVA against rapid worsening.

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.

Efficacy and mechanism of anti-vascular endothelial growth factor drugs for diabetic macular edema patients

BACKGROUND

Diabetes is a serious public health concern in China, with 30% of patients developing retinopathy, and diabetic macular edema (DME) having the biggest impact on vision. High blood glucose level can cause retinal cell hypoxia, thus promoting vascular endothelial growth factor (VEGF) formation and increasing vascular permeability, which induces DME. Moreover, cell hypoxia can accelerate the rate of apoptosis, which leads to the aging of patients. In severe cases, optic cell apoptosis or retinal fibrosis and permanent blindness may occur.

AIM

To investigate and compare the efficacy, mechanism, and differences between two anti-VEGF drugs (Compaq and ranibizumab) in DME patients.

METHODS

Ninety-six patients with DME who attended our hospital from April 2018 to February 2020 were included and randomly divided into two groups (Compaq group and ranibizumab group). The groups received vitreal cavity injections of 0.5 mg Compaq and 0.5 mg ranibizumab, respectively, once a month. The best corrected visual acuity (BCVA), intraocular pressure (IOP), macular retinal thickness (CMT), macular choroidal thickness (SFCT), foveal no perfusion area (FAZ), superficial capillary density, deep capillary density, treatment effect, and adverse reactions were compared before and after treatment and between the two groups.

RESULTS

Before treatment and 1-mo post-treatment, there was no statistically significant difference in the estimated BCVA in both groups (P > 0.05). BCVA decreased in the Compaq group 3 mo after treatment, and the difference was statistically significant (P < 0.05). Before treatment, and 1 mo and 3 mo post-treatment, there was no statistically significant difference in the estimated IOP in either group (P > 0.05). Before treatment and 1-mo post-treatment, there was no statistically significant difference in the estimated CMT, SFCT, or FAZ in either group (P > 0.05). CMT and SFCT values decreased in the Compaq group 3 mo post-treatment, and the difference was statistically significant (P < 0.05). Before treatment, and 1 mo and 3 mo post-treatment, there were no statistically significant differences in vascular density in the shallow or deep capillary plexi of the fovea, parafovea, or overall macular area between the two groups (P > 0.05). Marked efficient, effective, and invalid rates were 70.83% and 52.08%, 27.08% and 39.58%, and 2.08% and 8.33% in the Compaq and ranibizumab groups, respectively. The differences between the two groups were statistically significant (P < 0.05).

CONCLUSION

Anti-VEGF drugs can effectively improve CMT and SFCT, without affecting microcirculation, thus providing an effective and safe treatment for patients with DME.

Intravitreal Ranibizumab Alone or in Combination with Calcium Dobesilate for the Treatment of Diabetic Macular Edema in Nonproliferative Diabetic Retinopathy Patients: 12-Month Outcomes of a Retrospective Study

OBJECTIVE

This study investigates the efficacy of CaD combined with intravitreal ranibizumab for the treatment of diabetic macular edema (DME) in patients with nonproliferative DR.

METHODS

This retrospective, observational, case-control study enrolled consecutive patients newly diagnosed with DME. The patients were treated with 3-monthly loading dose injections of intravitreal ranibizumab (IVR) followed by pro re nata injections (3 + PRN), with or without daily oral CaD. The patients were treated and followed up for 12 months. We reviewed their medical records to determine the optical coherence tomography (OCT) findings, number of injections, best-corrected visual acuity (BCVA), and central macular thickness (CMT) at 3, 6, and 12 months after the first injection.

RESULTS

We reviewed 102 eyes of 102 patients; 54 patients received IVR combined with oral CaD (IVR + CaD group) and 48 received only IVR (IVR group). In both groups, BCVA was higher, and CMT was lower, at 3, 6, and 12 months after the injection compared to those at the baseline (p < 0.05 for all), while there were no significant differences in BCVA improvement or CMT reduction between the two groups (p > 0.05). The mean number of IVR injections was significantly lower in the IVR + CaD group than the IVR group (5.4 ± 1.1 vs. 6.7 ± 1.6 injections, p < 0.05) during 1 year of treatment. No adverse events were noted in either group.

CONCLUSIONS

Compared to IVR alone, the addition of oral CaD to IVR in DME patients was safe and effective for improving visual function and restoring the retinal anatomy and was associated with the need for fewer injections.

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.

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.