SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY IMAGING OF RETINAL CHANGES AFTER CONVENTIONAL MULTICOLOR LASER, SUBTHRESHOLD MICROPULSE DIODE LASER, OR PATTERN SCANNING LASER THERAPY IN JAPANESE WITH MACULAR EDEMA

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.

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 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.

Comparison of the efficacy and safety of subthreshold micropulse laser with photodynamic therapy for the treatment of chronic central serous chorioretinopathy: A meta-analysis

BACKGROUND

This meta-analysis was conducted to compare the therapeutic effect and safety of subthreshold micropulse laser (SML) vs photodynamic therapy (PDT) in treatment of chronic central serous chorioretinopathy (cCSC).

METHODS

PubMed, EMBASE, and the Cochrane Library were searched for all relevant studies published up to August 17, 2020. Data of interest were analyzed by STATA (version 14.0) software.

RESULTS

Four randomized clinical trials (RCTs) and 5 retrospective studies with 790 eyes were included in this meta-analysis after study selection. The results showed that SML significantly improved the best-corrected visual acuity (BCVA) compared with PDT at 6 to 8 weeks, 6 months, and 7 to 8 months in patients with cCSC (weighted mean difference (WMD) = -0.15, 95% confidence intervals (CI): -0.23 to -0.07, P < .01; WMD = -2.83, 95% CI: -4.79 to -0.87, P < .01; and WMD = -2.61, 95% CI: -4.23 to -1.24, P = .026, respectively). There was also a statistically significant difference between SML and PDT groups in the differences in the complete resolution of subretinal fluid (SRF) (risk radios = 0.388, 95% CI: 0.307 to 0.491, P < .01). There were no significant differences between the SML and PDT in the overall effect with central macular thickness (CMT), adverse events, complete resolution of SRF and treatment response.

CONCLUSIONS

Based on the available evidence, this meta-analysis demonstrated that SML may be considered as a competitive alternative to PDT for treating cCSC, and as the first-line treatment of cCSC.

Comparison of Subthreshold 532 nm Diode Micropulse Laser with Conventional Laser Photocoagulation in the Treatment of Non-Centre Involved Clinically Significant Diabetic Macular Edema

BACKGROUND

The aim of the study was to investigate the effect of the 532 nm (green) diode subthreshold micropulse laser (SML) in the treatment of non-centre involved clinically significant macular edema (CSME) in comparison to the conventional laser photocoagulation (CLP).

METHODS

A total of 60 eyes of patients diagnosed with non-centre involved CSME were randomly divided into two groups. SML photocoagulation was performed in the first group (G1), while CLP in the second one (G2). Central macular thickness (CMT) and best corrected visual acuity (BCVA) were measured prior to treatment and at 3 and 6 months after intervention.

RESULTS

G1 participants had significantly better CMT at 6 months after laser application (p = 0.04) compared to G2. Additionally, CMT in both groups was significantly lower 6 months after laser application in comparison to baseline values (G1: p < 0.001, G2: p = 0.002). Moreover, significant improvement was detected 6 months after SML in G1 regarding BCVA compared to values before laser treatment (p = 0.001).

CONCLUSION

SML was more effective than CLP in reducing CMT and improving BCVA in patients with non-centre involved CSME. Therefore, it seems that SML can be a good substitute for CLP in DME treatment if confirmed in future studies.

Comparison of the efficacy and safety between subthreshold micropulse laser, standard-fluence and low-fluence photodynamic therapy for chronic central serous chorioretinopathy

PURPOSE

To compare the efficacy and safety of subthreshold micropulse laser treatment (SML), standard-fluence photodynamic therapy (PDT) and low-fluence PDT in patients with chronic central serous chorioretinopathy (cCSC).

METHODS

This retrospective study included 52 eyes of 46 patients with chronic CSC who were treated with 577nm SML (n=23), standard-fluence PDT (verteporfin 6mg/m² and light energy 50J/cm²) (n=13), or low-fluence PDT (verteporfin 6mg/m² and light energy 25J/cm²) (n=16). The mean changes in best-corrected visual acuity (BCVA) and optical coherence tomography (OCT) parameters, including central retinal thickness (CRT), subretinal fluid (SRF) height, and ellipsoid zone (EZ) disruption, over the follow-up period were evaluated.

RESULTS

The mean follow-up period was 8.42±3.34 months. In the SML group, the SRF resolution time was longer than the other groups. At 1 month, the SML group's mean CRT was higher than the other groups. The BCVA improvement was statistically significant in all groups (P<0.05), but in the SML group, it was slower than the other groups. Three eyes in the low-fluence and one eye in the standard-fluence PDT group received a second PDT treatment. The mean number of SML treatments was 2.48±1.08. If the EZ was intact, the rate of complete resolution of SRF was higher than if the EZ was disrupted or lost.

CONCLUSION

SML, standard-fluence PDT, and low-fluence PDT can all improve visual acuity in cCSC. Standard-fluence and low-fluence PDT induced a more rapid reabsorption of the fluid, improvement of BCVA, and equal safety compared with SML. More treatment sessions of SML were required than with the other treatment modalities.

Transfoveal Micropulse Laser Treatment of Central Serous Chorioretinopathy within Six Months of Disease Onset

Background: It has been recommended that any invasive treatment performed in patients with central serous chorioretinopathy (CSCR) not be initiated earlier than four months after disease onset due to the potential for spontaneous remission of symptoms. The goal of this study was to examine the outcome of transfoveal subthreshold micropulse laser treatment (SMPLT) of CSCR performed at six months or less after disease onset. Materials and methods: The study included 32 cases of CSCR lasting between three weeks and six months (mean: 3.4 ± 2.3 months). All patients had transfoveal SMPLT applied and were followed for at least three months after each session of SMPLT. Two sessions of SMPLT in total were planned in case of an insufficient response to the first instance of treatment. Evaluation parameters included any change in best-corrected visual acuity (BCVA) and retinal morphology. Results: Total resolution of subretinal fluid (SRF) was noted in 26 cases (81.25%). Final BCVA improved significantly from 0.37 ± 0.22 logMAR to 0.22 ± 0.20 logMAR after treatment. Overall, early SMPLT correlated with better final BCVA (p = 0.0005, Spearman rank correlation). For eyes achieving a total resolution of SRF, BCVA improved from 0.33 ± 0.21 logMAR to 0.17 ± 0.14 logMAR (p = 0.004, Spearman rank correlation). The analysis of SMPLT nonresponders revealed a tendency for poorer baseline visual acuity. Conclusions: Patients with CSCR lasting six months or less treated with transfoveal SMPLT achieve better functional results with early application of this procedure. As baseline BCVA predicts final visual acuity, earlier treatment, permitted by the safety of SMPLT, may improve final visual outcomes.

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.

Short-term Efficacy of Micropulse Yellow Laser in Non-center-involving Diabetic Macular Edema: Preliminary Results

Objectives:

The aim of this study was to evaluate the efficacy of micropulse yellow laser (MPL) on best corrected visual acuity (BCVA) and retinal thickness in patients with non-center-involving diabetic macular edema (DME).

Materials and Methods:

We retrospectively reviewed 9 eyes of 8 patients with non-center-involving DME who underwent MPL treatment between January 2015 and December 2016. BCVA (logMAR) and retinal thickness were evaluated before and 3 months after treatment. Maximum retinal thickness was determined manually from simultaneous spectral-domain optical coherence tomography images and recorded. The change in the measurements from before to after treatment was analyzed statistically.

Results:

Of the 8 patients, 3 were female and 5 were male. The mean age was 52.8 years. Two of the 9 eyes had received previous intravitreal anti-vascular endothelial growth factor injection(s). Median BCVA was improved 3 months after treatment, although the difference was not statistically significant (0.34 logMAR before and 0.29 logMAR after treatment). BCVA was improved in 4 eyes while it showed no change in the remaining 5 eyes. The mean retinal thickness was 470.6 μm at baseline and 416 μm at 3 months after MPL treatment (p=0.01). Retinal thickness decreased in all eyes after treatment.

Conclusion:

In this study, parafoveal retinal thickness showed significant decrease after MPL treatment in patients with DME. The limited increase in BCVA may be due to the inclusion of a low number of patients and only those with non-center-involving macular edema. MPL may be used as an alternative to conventional argon laser in non-center-involving DME.

The impact of central foveal thickness on the efficacy of subthreshold micropulse yellow laser photocoagulation in diabetic macular edema

To evaluate the efficacy of short-term subthreshold micropulse yellow laser photocoagulation (SMYLP) on eyes with diabetic macular edema (DME) with different central foveal thicknesses (CFT). Eighty eyes of 40 patients who had previously undergone ranibizumab treatment for DME and who subsequently had recurrent macular edema were included to the study. The study subjects were divided into four groups according to their initial CFT values (group 1, 250-300 μm; group 2, 301-400 μm; group 3, > 401 μm; group 4, 250-300 μm untreated control subjects). Patients were treated with SMYLP for one session and followed for 6 months. All patients underwent complete ophthalmologic evaluation. The alteration from baseline in CFT and the best corrected visual acuity (BCVA) were measured. Patients with a pretreatment CFT ≤ 300 μm experienced the statistically significant reduction in CFT and gain in BCVA at 2 months (p < 0.05), whereas patients with baseline CFT > 300 μm experienced no significant change (p > 0.05). Hyperautofluorescence lesions, that were not previously described, were detected in fundus autofluorescence imaging in the early period after SYMLP laser and these lesions were regressed with time. Our study indicates that the SYMLP provides a statistically significant improvement in BCVA and a reduction in CFT in the patients with a pretreatment CFT of 300 μm or less in DME and can be safe and effective in mild DME treatment.

Optimizing optical coherence tomography and histopathology correlation in retinal imaging

OBJECTIVE

To develop a methodology to correlate optical coherence tomography (OCT) images and histopathological sections from the same eye. Part 1: To determine the best fixative for optimal OCT and histopathological analysis in post-mortem eyes. Part 2: A protocol is proposed to correlate histopathological features and OCT scans from the same post-mortem eyes.

DESIGN

Experimental study.

PARTICIPANTS

Part 1: Twenty-three rabbit eyes and 14 post-mortem human eyes. Part 2: Nineteen post-mortem human eyes.

METHODS

Part 1: Six different fixatives were tested, and specimens were evaluated on 4 criteria: globe shape, structure opacification, retinal detachment, and nuclear details. Part 2: Based on the findings from Part 1, fixed human eyes were imaged using OCT. Orientation-controlled histopathological processing was performed to obtain serial tissue sections from paraffin embedded tissue, which were matched to corresponding OCT images.

RESULTS

Part 1: Of the 6 fixatives, 2% glutaraldehyde and Davidson's solution met the proposed criteria in rabbit eyes. Of these, glutaraldehyde showed similar results in human eyes and was selected for Part 2. Part 2: Using anatomical landmarks, cross-sectional histopathological sections in the same orientation as the OCT images were correlated to their corresponding OCT images. Retinal lesions such as a macular hole, an epiretinal membrane, and the presence of drusen were easily correlated, proving the reliability of our methodology. Moreover, the photoreceptor's inner/outer junction was correlated to a hyperreflective band on OCT.

CONCLUSIONS

A standardized protocol was developed to correlate OCT images and histopathological findings by generating serial cross-sections of the retina, which can be used to better understand otherwise ambiguous OCT findings.

Comparison of ranibizumab and subthreshold micropulse laser in treatment of macular edema secondary to branch retinal vein occlusion

PURPOSE:

To compare the effects of intravitreal ranibizumab injection and yellow (577 nm) subthreshold micropulse laser treatment in patients with macular edema following non-ischemic branch retinal vein occlusion.

METHODS:

The medical records of 51 patients who underwent intravitreal ranibizumab (0.5 mg) injection or subthreshold micropulse laser for the treatment of macular edema due to branch retinal vein occlusion were retrospectively reviewed. Subthreshold micropulse laser was administered with a 10% duty cycle, 100 μm spot diameter, 200 ms exposure time. The patients received an injection or laser treatment at baseline and were, then, retreated as needed and were followed for 12 months. The mean best corrected visual acuity changes over the follow-up and the decrease in the mean central macular thickness were evaluated.

RESULTS:

A total of 27 and 24 patients were assigned to intravitreal ranibizumab and subthreshold micropulse laser subgroups, respectively. The mean number of treatment was 3.81 of intravitreal ranibizumab group and 1.5 of subthreshold micropulse laser group (p < 0.05). The subgroups were similar with regard to the mean score of best corrected visual acuity at baseline, at 1, 6, and 12 months (p > 0.05). The decrease in the mean central macular thickness was significant in both intravitreal ranibizumab and subthreshold micropulse laser groups at 1, 6, and 12 months than that of values at baseline (p < 0.05). No new ocular or systemic adverse events were observed.

CONCLUSION:

Our study results showed that intravitreal ranibizumab or yellow subthreshold micropulse laser treatment for macular edema due to branch retinal vein occlusion was not found to be superior to each other for reducing macular thickness and increasing visual acuity for 1-year period. Based on these results, subthreshold micropulse laser may be a useful alternative approach in the treatment of macular edema secondary to branch retinal vein occlusion.

New Developments in the Classification, Pathogenesis, Risk Factors, Natural History, and Treatment of Branch Retinal Vein Occlusion

For years, branch retinal vein occlusion is still a controversial disease in many aspects. An increasing amount of data is available regarding classification, pathogenesis, risk factors, natural history, and therapy of branch retinal vein occlusion. Some of the conclusions may even change our impression of branch retinal vein occlusion. It will be beneficial for our doctors to get a deeper understanding of this disease and improve the treatment skills. The aims of this review is to collect the information above and report new ideas especially from the past a few years.

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.

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.

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.

Modern diagnostic and treatment aspects of diabetic macular edema

Diabetic macular oedema (DMO) is the leading cause of vision loss and disability in working-age people with diabetes mellitus. This literature review describes pathogenetic mechanisms, concepts, diagnostic techniques and capabilities of novel laser technologies in the treatment of DMO. In recent years, the role of cytokines and growth factors in retinal neurodegeneration has been actively investigated. Modern diagnostic techniques for the treatment of diabetic macular oedema, in addition to conventional techniques, include optical coherence tomography, autofluorescence and microperimetry. These techniques allow the visualization of retinal structures and its functional condition, and they can be used to detect DMO at early stages and to provide the most effective treatment. The evolution of laser technology resulted in the formation of new approaches to DMO treatment. Subthreshold micropulse laser (SML) treatment, in conjunction with conventional photocoagulation, has pronounced therapeutic effects. SML shows high selectivity towards retinal pigment epithelium while avoiding neurosensory retina injury. Owing to the chronic nature of DMO and pathogenetic mechanisms recently discovered, further elaboration of the SML technique appears to be a very promising 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.

Pathophysiology and treatment of diabetic retinopathy

In the past years, the management of diabetic retinopathy (DR) relied primarily on a good systemic control of diabetes mellitus, and as soon as the severity of the vascular lesions required further treatment, laser photocoagulation or vitreoretinal surgery was done to the patient. Currently, even if the intensive metabolic control is still mandatory, a variety of different clinical strategies could be offered to the patient. The recent advances in understanding the complex pathophysiology of DR allowed the physician to identify many cell types involved in the pathogenesis of DR and thus to develop new treatment approaches. Vasoactive and proinflammatory molecules, such as vascular endothelial growth factor (VEGF), play a key role in this multifactorial disease. Current properly designed trials, evaluating agents targeting VEGF or other mediators, showed benefits in the management of DR, especially when metabolic control is lacking. Other agents, directing to the processes of vasopermeability and angiogenesis, are under investigations, giving more hope in the future management of this still sight-threatening disease.