Subthreshold Diode Micropulse Laser: A Review

Recent advances in the treatment and delivery system of diabetic retinopathy

Diabetic retinopathy (DR) is a highly tissue-specific neurovascular complication of type 1 and type 2 diabetes mellitus and is among the leading causes of blindness worldwide. Pathophysiological changes in DR encompass neurodegeneration, inflammation, and oxidative stress. Current treatments for DR, including anti-vascular endothelial growth factor, steroids, laser photocoagulation, and vitrectomy have limitations and adverse reactions, necessitating the exploration of novel treatment strategies. This review aims to summarize the current pathophysiology, therapeutic approaches, and available drug-delivery methods for treating DR, and discuss their respective development potentials. Recent research indicates the efficacy of novel receptor inhibitors and agonists, such as aldose reductase inhibitors, angiotensin-converting enzyme inhibitors, peroxisome proliferator-activated receptor alpha agonists, and novel drugs in delaying DR. Furthermore, with continuous advancements in nanotechnology, a new form of drug delivery has been developed that can address certain limitations of clinical drug therapy, such as low solubility and poor penetration. This review serves as a theoretical foundation for future research on DR treatment. While highlighting promising therapeutic targets, it underscores the need for continuous exploration to enhance our understanding of DR pathogenesis. The limitations of current treatments and the potential for future advancements emphasize the importance of ongoing research in this field.

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.

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.

Hormetic Heat Shock Enhances Autophagy through HSF1 in Retinal Pigment Epithelium Cells

To maintain homeostasis, cells have evolved stress-response pathways to cope with exogenous and endogenous stress factors. Diverse stresses at high doses may be detrimental, albeit low doses of stress, known as hormesis, can be beneficial. Upon exposure to stress, such as temperature rise, the conventional heat shock response (HSR) regulated by the heat shock transcription factor 1 (HSF1) facilitates refolding of misfolded proteins with the help of heat shock proteins (HSPs). However, the role and molecular mechanisms underlying the beneficial effects of HSR with other clearance processes, such as autophagy, remain poorly understood. In this study, human ARPE-19 cells, an in vitro model of retinal pigment epithelium, were treated with hormetic heat shock (HHS) and the autophagy expression profile was examined using quantitative PCR (qPCR), immunoblotting, immunoprecipitation, and immunofluorescence. We demonstrate that HHS enhances the expression of fundamental autophagy-associated genes in ARPE-19 cells through the activation of HSF1. HHS transiently increases the level of SQSTM1 and LC3B-II and activates autophagy. These findings reveal a role for autophagic HSF1-regulated functions and demonstrate the contribution of autophagy to hormesis in the HSR by improving proteostasis.

Efficacy and Safety of Micropulse Transscleral Laser Therapy in Silicone Oil-induced Glaucoma

PURPOSE

To assess the efficiency and safety of MicroPulse® Transscleral Laser Therapy (TLT) in the management of silicone oil-induced glaucoma.

METHODS

A prospective case series of 33 eyes with uncontrolled silicone oil-induced glaucoma was enrolled at the department of ophthalmology of Mohamed Taher Maamouri Hospital, Nabeul, Tunisia. Patients were treated with MicroPulse TLT using the IRIDEX Cyclo G6® Glaucoma Laser System with the MicroPulse P3® fiberoptic handheld probe. Patients underwent complete ophthalmologic examination during the 12-month follow-up period.

RESULTS

The study included 33 eyes of 33 patients. The mean age was 50.39 years old. We included patients with silicone oil-induced glaucoma. Silicone oil tamponade was indicated for complicated rhegmatogenous retinal detachment in 22 cases, diabetic tractional retinal detachment in 10 cases, and post-traumatic retinal detachment in one case. Silicone oil was already removed before the procedure in 23 eyes. Silicone oil tamponade duration varied between 3 to 26 months. IOP measurements at enrolment, day 1, day 7, day 15, 1 month, 3 months, 6 months and 12 months was respectively 37.94±13.61, 19.03±10.98, 16.5±6.17, 19.45±9.73, 19.27±8.33, 19.39±9.52, 19.97±10.03 and 19.7±9.58▒mmHg. The percentage of IOP lowering was 45.38% at 6 months and 45% at 12 months. The success rate was 93.93% at 6 months remaining stable at 12 months. No major side effects were observed, in particular, no phthisis bulbi nor prolonged inflammation. There was no difference in IOP lowering between patients with silicone oil or those after silicone oil removal (P=0.99).

CONCLUSION

MP-TLT was safe and effectively lowered intraocular pressure in uncontrolled silicone-oil induced glaucoma.

Long-term results of micropulse laser trabeculoplasty with 577-nm yellow wavelength in patients with uncontrolled primary open-angle glaucoma and pseudoexfoliation glaucoma

Our aim was to evaluate the long-term results of micropulse laser trabeculoplasty (MLT) with 577-nm yellow wavelength in the treatment of glaucoma. We reviewed the medical records of 51 patients (51 eyes) with uncontrolled primary open-angle glaucoma or pseudoexfoliation glaucoma who underwent 180° MLT for the first time. The success of MLT was defined as an IOP reduction of ≥ 20% and IOP < 21 mmHg after treatment. If the number of medications was increased or further laser trabeculoplasty or glaucoma surgery was required after treatment, the case was considered unsuccessful. The mean duration of patient follow-up was 18.39 ± 12.17 months (range 3-52 months). Patients included in the study used 2-4 types of antiglaucoma eye drops (mean 3.43 ± 0.7). The mean number of MLT spots was 65.54 ± 6.19, and the mean energy level was 750.98 ± 101.73 mJ. The decrease in intraocular pressure compared to baseline measurements was: 16.72 ± 11.87%, 15.07 ± 13.76%, 12.63 ± 14.29%, 16.66 ± 19.32%, and 16.75 ± 19.78% during follow-up at 3, 6, 12, 24, and 36-48 months. Successful response was achieved in 35.41%, 36.95%, 34.21%, 40%, 41.17%, and 42.85% of patients during 3, 6, 12, 18, 24, and 36-48 months of follow-ups, respectively. Of the 51 eyes studied, 12 patients (23.5%) underwent post-MLT glaucoma surgery, and 7 patients (13.7%) had cataract surgery, whose follow-up data were subsequently censored. The reduction of intraocular pressure showed a significant correlation with baseline intraocular pressure, while age and laser power showed no correlation (p > 0.05). MLT is a novel treatment option for patients with glaucoma with favorable long-term outcomes and a good safety profile.

Factors affecting the response to subthreshold micropulse laser therapy used in center-involved diabetic macular edema

The purpose of this study was to investigate the effect of the status of retinal pigment epithelium (RPE) and HbA1c levels on the efficacy of the subthreshold micropulse laser (SMPL) in the treatment of center-involving diabetic macular edema (DME). A total of 20 eyes of 20 patients (mean age 57.9 ± 9.7 years) who were diagnosed with center-involving DME and treated with SMPL for refusing intravitreal injection and 20 eyes of 20 age- and sex-matched healthy participants were enrolled. All patients were followed up in the 1st and 3rd months after SMPL. For measurement of RPE area central 1000 microns, macular EDI-OCT scans were binarized by using the public domain software ImageJ, with a semi-automated technique. There was a significant increase in BCVA values and a significant decrease in CMT values during follow-up. The area of RPE before SMPL was significantly thinner in the patient group (p: 0.004). When the areas of RPE before and 3 months after SMPL were compared, no significant change was observed (p: 0.437). When the relationship between pre-treatment area of RPE and HbA1c was examined, an inverse correlation was observed (p: 0.018). The patients were evaluated by dividing them into 2 groups as 2nd session SMPL required and not required, and the area of RPE was smaller in the group requiring 2nd session SMPL (p: 0.030). The status of central RPE may be a determining factor on the response to treatment. Additionally, HbA1c levels may have an impact on treatment efficacy.

Investigations on Retinal Pigment Epithelial Damage at Laser Irradiation in the Lower Microsecond Time Regime

Purpose

New lasers with a continuous wave power exceeding 15 W are currently investigated for retinal therapies, promising highly localized effects at and close to the Retinal Pigment Epithelium (RPE). The goal of this work is to evaluate mechanisms and thresholds for RPE cell damage by means of pulse durations up to 50 µs.

Methods

A diode laser with a wavelength of 514 nm, a power of 15 W, and adjustable pulse durations between 2 µs and 50 µs was used. Porcine RPE-choroidal explants (ex vivo) and chinchilla bastard rabbits (in vivo) were irradiated to determine threshold radiant exposures for RPE damage H¯Cell by calcein vitality staining and fluorescence angiography, respectively. Thresholds for microbubble formation (MBF) H¯MBF were evaluated by time-resolved optoacoustics. Exemplary histologies support the findings.

Results

H¯MBF is significantly higher than H¯Cell at pulse durations ≥ 5 µs (P < 0.05) ex vivo, while at 2 µs, no statistically significant difference was found. The ratios between H¯MBF and H¯Cell increase with pulse duration from 1.07 to 1.48 ex vivo and 1.1 to 1.6 in vivo, for 5.2 and 50 µs.

Conclusions

Cellular damage with and without MBF related disintegration are both present and very likely to play a role for pulse durations ≥ 5 µs. With the lower µs pulses, selective RPE disruption might be possible, while higher values allow achieving spatially limited thermal effects without MBF. However, both modi require a very accurate real-time dosing control in order to avoid extended retinal disintegration in this power range.

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 anti-VEGF monotherapy versus anti-VEGF therapy combined with subthreshold micropulse laser therapy for diabetic macular edema

The purpose of this study is to compare the efficacy and safety of 577-nm subthreshold micropulse laser (SML) and intravitreal bevacizumab injection (IVB) combined therapy with IVB monotherapy in the treatment of diabetic macular edema (DME). This retrospective study included 80 eyes of 80 patients; 40 eyes were treated with IVB monotherapy, and 40 eyes were treated with SML-IVB combined therapy. The mean number of required IVB injections and changes of best corrected visual acuity (BCVA) and central macular thickness (CMT) values were compared between the groups. The mean age of the patients was 60.19±7.43 years. The baseline characteristics of the patients were similar between the groups. In the SML-IVB combined group, the mean number of required SML sessions was 2.1±0.81. The mean number of required IVB injections was 4.38±0.81 in the SML-IVB combined group and 5.65±1.51 in the IVB monotherapy group (p<0.05). The increase of the BCVA was significant in the SML-IVB combined group at the 3rd, 6th, 9th, and 12th months; however, in the IVB monotherapy group, it was only significant at the 3rd month (p<0.05). The mean CMT values of the 3rd, 9th, and 12th months were similar between the groups (p>0.05); only at the 6th month was it significantly lower in the SML-IVB combined group (p<0.05). When compared with baseline, the decrease of the CMT was statistically significant in both groups at the 3rd, 6th, 9th, and 12th months (p<0.05). In this study, a significant benefit of adding SML to IVB therapy was found with less IVB need, although a very significant increase in BCVA could not be achieved. The use of SML-IVB combined treatment may be an effective and safe alternative for DME.

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

Objective: intravitreal therapy for macular edema (ME) is a common clinical approach to treating most retinal vascular diseases; however, it generates high costs and requires multiple follow-up visits. Combining intravitreal anti–vascular endothelial growth factor (VEGF) or steroid therapy with subthreshold diode micropulse laser (SDM) application could potentially reduce the burden of numerous intravitreal injections. This review sought to explore whether this combination treatment is effective in the course of ME secondary to retinal vascular disease, and in particular, determine whether it is comparable or superior to intravitreal therapy alone. Materials and methods: the following terms and Boolean operators were used to search the PubMed literature database: subthreshold micropulse laser, subthreshold diode micropulse OR micropulse laser treatment AND anti-VEGF, anti-VEGF treatment, intravitreal steroids, OR combined therapy.This analysis included all studies discussing the combination of SDM and intravitreal anti-VEGF or steroid treatment. Results: the search revealed nine studies that met the inclusion criteria, including five comparing combined treatment and anti-VEGF treatment alone, four covering diabetic ME, and one covering ME secondary to branch retinal vein occlusion. All of these five studies suggested that combination therapy results in fewer intravitreal injections than anti-VEGF monotherapy with non-inferior functional and morphological outcomes. The remaining four studies report functional and morphological improvements after combined treatment; however, SDM alone was never superior to intravitreal-alone or combined treatment. There were substantial differences in treatment protocols and inclusion criteria between the studies. Conclusions: the available material was too scarce to provide a reliable assessment of the effects of combined therapy and its relation to intravitreal monotherapy in the treatment of ME secondary to retinal vascular disease. One assumption of note is that it is possible that SDM plus anti-VEGF might require fewer intravitreal injections than anti-VEGF monotherapy with equally good functional and morphological results. However, further randomized research is required to confirm this thesis.

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.

Can subthreshold micropulse yellow laser treatment change the anti-vascular endothelial growth factor algorithm in diabetic macular edema? A randomized clinical trial

Purpose

To compare the efficacy of subthreshold micropulse yellow laser (SMYL) and intravitreal aflibercept injection (IAI) combination therapy with IAI monotherapy in the treatment of diabetic macular edema (DME) and to evaluate the number of injections and SMYL sessions required.

Methods

This prospective study compared a group of 28 patients treated with a combination of SMYL and IAI with a group of 28 patients treated only with IAI. All patients initially received 3 monthly IAIs, and the monotherapy group was given additional injections as needed. The combination therapy patients additionally received SMYL after the loading phase. The primary outcome measures were the change in the best-corrected visual acuity (BCVA) and central macular thickness (CMT) from baseline to month 12; the secondary outcomes were the mean number of required injections and SMYL sessions.

Results

In the monotherapy group, the BCVA improved from 0.38 ± 0.10 to 0.20 ± 0.10 logMAR; in the combination group, BCVA improved from 0.40 ± 0.09 to 0.17 ± 0.06 logMAR at the end of the 12^th month. The CMT was reduced from 451.28 ± 44.85 to 328.8 ± 49.69 μm in the monotherapy group and from 466.07 ± 71.79 to 312.0 ± 39.29 μm in the combination group. Improvement of the mean BCVA and reduction of the mean CMT were similar in each group. The combination group required significantly fewer injections (3.21 ± 0.41 vs 5.39 ± 1.54; P < 0.001). By month 12, 75% of patients in the monotherapy group had required additional IAIs when compared with 16% in the combination group (P < 0.001).

Conclusion

SMYL combination therapy demonstrated significant visual improvements in patients with DME. In the combination group, the retreatment rate and number of required injections were significantly lower compared with the IAI monotherapy group.

Efficacy and safety of subthreshold micropulse laser compared with threshold conventional laser in central serous chorioretinopathy

PURPOSE

To compare the efficacy and safety of subthreshold micropulse laser (SML) with threshold conventional laser (TCL) in central serous chorioretinopathy (CSC).

METHODS

Prospective, randomized, double-masked, non-inferiority, 12-week clinical trial. Patients were randomly assigned 1:1 to SML group or TCL group. Patients in the SML group were treated with 577 nm micropulse laser. The spot size was 160 µm, the duty cycle was 5% and exposure time was 0.2 s. The power was 50% threshold tested. Patients in the TCL group were treated with 577 nm continuous laser. The power was 100% threshold tested. The primary outcome was the mean change in best-corrected visual acuity (BCVA) at week 12, with a non-inferiority limit of five letters on the Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity charts.

RESULTS

Eighty-eight patients were enroled. Seventy-seven patients were male. Forty-four patients were in SML group and 44 in TCL group. At week 12, SML was equivalent to TCL with a gain of 6.23 ± 8.59 and 6.61 ± 6.35 letters, respectively, (SML-TCL difference: -0.38 letters; 95% confidence interval (CI):-3.58-2.81; Pnon-inferiority = 0.0026). There was no statistically significant difference between the two groups (t = 0.240, P = 0.811). At week 12, the proportion of patients whose SRF had been totally absorbed was 63.63 and 81.82% respectively for SML and TCL groups. There was no statistically significant difference between the two groups (χ2 = 3.67, P = 0.056).

CONCLUSIONS

Both SML and TCL can improve visual acuity in CSC. SML was non-inferior to TCL in the improvement of BCVA.

Induction of Heat Shock Protein 70 in Mouse RPE as an In Vivo Model of Transpupillary Thermal Stimulation

The induction of heat shock response in the macula has been proposed as a useful therapeutic strategy for retinal neurodegenerative diseases by promoting proteostasis and enhancing protective chaperone mechanisms. We applied transpupillary 1064 nm long-duration laser heating to the mouse (C57Bl/6J) fundus to examine the heat shock response in vivo. The intensity and spatial distribution of heat shock protein (HSP) 70 expression along with the concomitant probability for damage were measured 24 h after laser irradiation in the mouse retinal pigment epithelium (RPE) as a function of laser power. Our results show that the range of heating powers for producing heat shock response while avoiding damage in the mouse RPE is narrow. At powers of 64 and 70 mW, HSP70 immunostaining indicates 90 and 100% probability for clearly elevated HSP expression while the corresponding probability for damage is 20 and 33%, respectively. Tunel staining identified the apoptotic regions, and the estimated 50% damaging threshold probability for the heating (ED50) was ~72 mW. The staining with Bestrophin1 (BEST1) demonstrated RPE cell atrophy with the most intense powers. Consequently, fundus heating with a long-duration laser provides an approachable method to develop heat shock-based therapies for the RPE of retinal disease model mice.

Treatments for dry age-related macular degeneration and Stargardt disease: a systematic review

BACKGROUND

Age-related macular degeneration (AMD) is the leading cause of visual loss in older people. Advanced AMD takes two forms, neovascular (wet) and atrophic (dry). Stargardt disease (STGD) is the commonest form of inherited macular dystrophy.

OBJECTIVE

To carry out a systematic review of treatments for dry AMD and STGD, and to identify emerging treatments where future NIHR research might be commissioned.

DESIGN

Systematic review.

METHODS

We searched MEDLINE, EMBASE, Web of Science and The Cochrane Library from 2005 to 13 July 2017 for reviews, journal articles and meeting abstracts. We looked for studies of interventions that aim to preserve or restore vision in people with dry AMD or STGD. The most important outcomes are those that matter to patients: visual acuity (VA), contrast sensitivity, reading speed, ability to drive, adverse effects of treatment, quality of life, progression of disease and patient preference. However, visual loss is a late event and intermediate predictors of future decline were accepted if there was good evidence that they are strong predictors of subsequent visual outcomes. These include changes detectable by investigation, but not necessarily noticed by people with AMD or STGD. ClinicalTrials.gov, the World Health Organization search portal and the UK Clinical Trials gateway were searched for ongoing and recently completed clinical trials.

RESULTS

The titles and abstracts of 7948 articles were screened for inclusion. The full text of 398 articles were obtained for further screening and checking of references and 112 articles were included in the final report. Overall, there were disappointingly few good-quality studies (including of sufficient size and duration) reporting useful outcomes, particularly in STGD. However we did identify a number of promising research topics, including drug treatments, stem cells, new forms of laser treatment, and implantable intraocular lens telescopes. In many cases, research is already under way, funded by industry or governments.

LIMITATIONS

In AMD, the main limitation came from the poor quality of much of the evidence. Many studies used VA as their main outcome despite not having sufficient duration to observe changes. The evidence on treatments for STGD is sparse. Most studies tested interventions with no comparison group, were far too short term, and the quality of some studies was poor.

FUTURE WORK

We think that the topics on which the Health Technology Assessment (HTA) and Efficacy Mechanism and Evaluation (EME) programmes might consider commissioning primary research are in STGD, a HTA trial of fenretinide (ReVision Therapeutics, San Diego, CA, USA), a visual cycle inhibitor, and EME research into the value of lutein and zeaxanthin supplements, using short-term measures of retinal function. In AMD, we suggest trials of fenretinide and of a potent statin. There is epidemiological evidence from the USA that the drug, levodopa, used for treating Parkinson's disease, may reduce the incidence of AMD. We suggest that similar research should be carried out using the large general practice databases in the UK. Ideally, future research should be at earlier stages in both diseases, before vision is impaired, using sensitive measures of macular function. This may require early detection of AMD by screening.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016038708.

FUNDING

The National Institute for Health Research HTA programme.

Low incidence of choroidal neovascularization following subthreshold diode micropulse laser (SDM) in high-risk AMD

Purpose

To determine the incidence of new choroidal neovascularization (CNV) in eyes with dry age-related macular degeneration (AMD) following subthreshold diode micropulse laser (SDM).

Method

In an observational retrospective cohort study, the records of all patients active in the electronic medical records database were reviewed to identify eyes with dry AMD treated with SDM. Identified eyes were classified by simplified AREDS categories, and analyzed for the primary endpoint of new CNV after treatment.

Results

The EMR revealed SDM was offered to 373/392 (95%) patients with dry AMD and elected by 363/373 (97%) between 2008–2017. Follow up was available for 354/363 patients (547 eyes, 98%) (range 6–108 mos., avg. 22). CNV risk factors included age (median 84 years, 67% > 80); reticular pseudodrusen (214 eyes, 39%); AREDS category (78% category 3 and 4); and fellow eye CNV (128 eyes, 23%). New CNV developed in 9/547 eyes (1.6%, annualized rate 0.87%). Visual acuity was unchanged. There were no adverse treatment effects.

Summary

In a review of a large group of eyes with exceptionally high-risk AMD, SDM was followed by a very low incidence of new CNV. If confirmed by further study, SDM would offer a new and highly effective treatment to reduce the risk of vision loss from AMD.

SUBTHRESHOLD LASER TREATMENT FOR SEROUS RETINAL DETACHMENT IN DOME-SHAPED MACULA ASSOCIATED WITH PATHOLOGIC MYOPIA

PURPOSE

To evaluate the effects of the subthreshold laser treatment as a therapeutic option in the treatment of serous retinal detachment secondary to dome-shaped macula.

METHODS

Prospective pilot study with 12-month follow-up. Each patient underwent a complete ophthalmologic examination, including best-corrected visual acuity, fluorescein angiography, indocyanine green angiography, and spectral domain optical coherence tomography. Eyes with persistent serous retinal detachment lasting for a minimum of 12 months and absence of best-corrected visual acuity improvement underwent subthreshold laser treatment in a single session. The laser spots were delivered in a contiguous mode, covering the area of hyperfluorescence recognized on indocyanine green angiography. The primary outcome measure was the best-corrected visual acuity changes at the 12-month examination. Secondary outcomes included changes in central foveal thickness (CFT) and number of eyes achieving a complete serous retinal detachment resolution.

RESULTS

Twelve eyes (8 patients) were included in the study. Best-corrected visual acuity changed from a baseline value of 0.8 ± 0.2 (±SD, logarithm of the minimum angle of resolution [Snellen equivalent: 20/125]) to 0.48 ± 0.1 (Snellen equivalent: 20/60, P = 0.001). Central foveal thickness decreased from 320 ± 52 μm to a final value of 266 ± 41 μm (P = 0.001). Serous retinal detachment reduced in all cases; however, just one eye (8.3%) showed a complete resolution at the 12-month examination. Fluorescein angiography and indocyanine green angiography showed that the hyperfluorescence had disappeared after subthreshold laser treatment. No adverse event was registered, including enlargement of atrophic alterations and choroidal neovascularization.

CONCLUSION

Subthreshold laser treatment can lead to improvements in visual acuity and central foveal thickness in myopic eyes with serous retinal detachment secondary to dome-shaped macula. Further studies are required to confirm our preliminary results.

Improved retinal and visual function following panmacular subthreshold diode micropulse laser for retinitis pigmentosa

Objectives

To examine the effect of subthreshold diode micropulse laser (SDM) on pattern electroretinography (PERG) and visual function in retinitis pigmentosa (RP).

Methods

The records of all patients (pts) undergoing SDM in a vitreoretinal subspecialty practice were reviewed. Inclusion criteria included the presence of RP evaluated before and after SDM by PERG. As a secondary outcome measure, the results of automated omnifield resolution perimetry (ORP) were also reviewed.

Results

All eyes undergoing SDM for RP were eligible study, including 26 eyes of 15 pts; seven male and eight female, aged 16–69 (avg. 47) years. Retinal function by PERG improved by all indices, with significant improvements in the 24° field signal latency measures; the MagD(µV)/ Mag(µV) ratio (P < 0.0001) and the MagD(µV) amplitude (P = 0.0003). ORP significantly improved by all indices (p = 0.02–0.002). Average best-corrected chart visual acuities improved from 0.6 to 0.4 logMAR units (p = 0.02). There were no adverse treatment effects.

Conclusions

SDM significantly improved chart visual acuity, mesopic logMAR visual acuity perimetry, and retinal function by PERG in RP without adverse treatment effects. Treatment responses indicate a significant capacity for rescue of dysfunctional retina. These results suggest that early and periodic treatment with SDM might slow disease progression and reduce long-term vision loss.

Functional and morphological outcome in patients with chronic central serous chorioretinopathy treated by subthreshold micropulse laser

Background

Chronic central serous chorioretinopathy is a serious therapeutic problem as it may lead to significant visual impairment. The aim of this retrospective study is to evaluate functional and morphological effects, as well as factors influencing visual outcome in patients treated by subthreshold micropulse laser.

Methods

Fifty-one eyes with chronic central serous chorioretinopathy lasting longer than 4 months (18 months on average) underwent up to two sessions of subtreshold micropulse laser treatment. Change in best corrected visual acuity, central retinal thickness, central retinal volume, average central retinal thickness and maximum subretinal fluid height were measured. Relation between the effects of the treatment and the initial retinal morphological and functional parameters was then analyzed.

Results

The total resorption of subretinal fluid was achieved in 36 cases (70.6%). There was, however, only a minor improvement in best corrected visual acuity of approximately one line on the Snellen chart. No correlation was observed between the effects of the treatment and the duration of the symptoms, retinal morphology and initial visual acuity. Younger patients responded better to the therapy.

Conclusion

Subthreshold micropulse laser treatment in chronic serous chorioretinopathy provides good morphological results, however significant improvement of visual acuity is not to be expected.

Subthreshold Nanosecond Laser Intervention in Intermediate Age-Related Macular Degeneration: Study Design and Baseline Characteristics of the Laser in Early Stages of Age-Related Macular Degeneration Study (Report Number 1)

PURPOSE

The Laser Intervention in Early Stages of Age-Related Macular Degeneration (LEAD) study is an investigation of the safety and efficacy of subthreshold nanosecond laser treatment to slow the progression of intermediate age-related macular degeneration (AMD). This report presents the novel study design and baseline characteristics.

DESIGN

Multicenter, double-masked, randomized controlled, medical device feasibility clinical trial.

PARTICIPANTS

Persons with bilateral drusen >125 μm within 1500 μm of the fovea, monocular best-corrected visual acuity (BCVA) ≥20/40, and microperimetric retinal sensitivity of <25 decibels (dB) in at least 1 location within central 6° in 1 eye. Signs of late AMD; choroidal neovascularization or geographic atrophy, or anatomic end points defined on multimodal imaging (MMI) as fundus autofluorescence-defined atrophy, spectral-domain OCT (SD-OCT)-defined atrophy, or nascent GA excluded participation.

METHODS

Participants were randomized to nanosecond or sham laser treatment. Twelve laser or sham spots are applied to the macular region of the study eye. Participants are reviewed in visits every 6 months with functional testing and MMI for 36 months and are re-treated at each visit (until 30 months) if an end point is not reached in the study eye.

MAIN OUTCOME MEASURES

Progression to late AMD or MMI-defined anatomic end points in the study eye.

RESULTS

A total of 292 participants across 6 centers were enrolled, with 145 participants randomized to arm 1 and 147 participants randomized to arm 2. Population characteristics at baseline were as follows: median age 70 years, 73% female, 90% Anglo-Saxon, and 3% current smokers. Baseline ocular characteristics of the study eyes were BCVA of 83 letters (20/25); low luminance visual acuity (LLVA) of 68 letters (20/50); hyperpigmentation, 33%; reticular pseudodrusen, 23%; square root drusen area (SD-OCT), 0.77 mm; square root drusen area (color photographs), 0.92 mm; cube root drusen volume (SD-OCT), 0.26 mm; average retinal sensitivity, 26 dB; and worst point retinal sensitivity, 20 dB. Only lutein supplement use was significantly different between treatment arms.

CONCLUSIONS

The LEAD study uses novel inclusion/exclusion criteria and end points in an attempt to optimize our study design. Risk characteristics for progression to study end points are equally distributed between treatment arms.