Subthreshold Laser Research Articles

The efficacy of subthreshold micropulse yellow laser (577 nm) in chronic central serous chorioretinopathy.

Central serous chorioretinopathy (CSC) is a disease characterized by a well-defined serous detachment of the neurosensory retina. Therapeutic options in chronic cases are limited, and side effects can result in a limited response. The aim of this article is to assess the efficacy of subthreshold micropulse laser therapy in patients with chronic central serous chorioretinopathy. The study included 20 eyes of 19 patients who had a history of chronic or chronic recurrent CSC and who underwent subthreshold micropulse laser therapy between January 2015 and June 2018. Twenty eyes of 19 patients with a mean age of 48.9 ± 9.40 years were included. The mean visual acuity was 0.24 ± 0.28 logMAR before laser, 0.19 ± 0.25 logMAR 3 months after laser, and 0.18 ± 0.27 logMAR after 6 months. A statistically significant difference was determined in terms of visual acuity before and after treatment (p = 0.0001). The mean central retinal thickness was 308.10 ± 95.25 μm before laser, 233.65 ± 81.17 μm 3 months after laser, and 203.88 ± 72.79 μm at 6 months. A statistically significant relationship was present between visual acuity and the duration of disease (p = 0.001), between visual acuity and the outer nuclear layer thickness (p = 0.005), and between the outer nuclear layer thickness and the duration of disease in chronic cases (p = 0.008). There was no evidence of retinal pigment epithelium or retinal damage on optical coherence tomography or fundus autofluorescence secondary to subthreshold micropulse laser therapy. Visual acuity appears to be more associated with the duration of disease and with changes in the outer nuclear layer thickness in chronic CSC. Subthreshold micropulse laser therapy seems to be effective at treating chronic CSC, while it increases success during early period of the disease before the development of permanent retinal damage.

Optical coherence tomography angiography assessment of 577 nm laser effect on severe non-proliferative diabetic retinopathy with diabetic macular edema.

To quantitatively evaluate the effect of the combined use of 577-nm subthreshold micropulse macular laser (SML) and multi-point mode pan retinal laser photocoagulation (PRP) on severe non-proliferative diabetic retinopathy (NPDR) with central-involved diabetic macular edema (CIDME) using optical coherence tomography angiography (OCTA). In this observational clinical study, 86 eyes of 86 NPDR patients with CIDME who underwent SML and PRP treatment were included. Images were obtained 1d before laser and post-laser (1d, 1wk, 1, 3, and 6mo) using AngioVue software 2.0. Best corrected visual acuity (BCVA, LogMAR), foveal avascular zone area (FAZ), choriocapillary flow area (ChF), parafoveal vessel density (PVD), capillary density inside disc (CDD), peripapillary capillary density (PCD), macular ganglion cell complex thickness (mGCCT), central macular thickness (CMT), and subfoveal choroidal thickness (ChT) were compared between pre- and post-laser treatment. BCVA remained stable during 6mo post-laser therapy (pre-laser vs 6mo post-laser: 0.53±0.21 vs 0.5±0.15, P>0.05). PVD, ChF, ChT, CMT, and mGCCT significantly increased 1d post-laser therapy [pre-laser vs 1d post-laser: superficial PVD (%), 40.51±3.42 vs 42.43±4.68; deep PVD (%), 42.66±3.67 vs 44.78±4.52; ChF, 1.72±0.21 vs 1.9±0.12 mm2; ChT, 302.45±69.74 vs 319.38±70.93 µm; CMT, 301.65±110.78 vs 320.86±105.62 µm; mGCCT, 105.71±10.72 vs 115.46±9.64 µm; P<0.05]. However, PVD, ChF and ChT decreased to less than baseline level at 6mo post-laser therapy (pre-laser vs 6mo post-laser: superficial PVD (%), 40.51±3.42 vs 36.32±4.19; deep PVD (%), 42.66±3.67 vs 38.76±3.74; ChF, 1.72±0.21 vs 1.62±0.09 mm2; ChT, 302.45±69.74 vs 289.61±67.55 µm; P<0.05), whereas CMT and mGCCT decreased to baseline level at 6mo post-laser therapy (CMT, 301.65±110.78 vs 297.77±90.23 µm; mGCCT, 105.71±10.72 vs 107.05±11.81 µm; P>0.05). Moreover, FAZ continuously increased while CDD and PCD continuously decreased in 6mo after laser therapy. CMT and ChT had a significant positive correlation with ChF and PVD in most post-laser stages. During a 6-month follow-up period after combined use of SML and PRP therapy, BCVA remained stable and there was a decreased trend in macular edema. Blood flow increased at 1d post-laser therapy and reduced at 6mo post-laser therapy.

Multi-focal electro-retinogram response following sub-threshold nano-second laser intervention in age-related macular degeneration.

The effect of sub-threshold nano-second laser (SNL) treatment on retinal function remains unknown. SNL treatment has been studied as a potential intervention in intermediate age-related macular degeneration (iAMD). This study investigated the longitudinal effect of SNL treatment on retinal function. This was a sub-study of the LEAD trial; a 36-month, multi-centre, randomized and sham-controlled trial. Subjects with iAMD. Eligible participants were assigned randomly to receive SNL or sham treatment to the study eye at 6-monthly visits. Multi-focal electro-retinography (mfERG) was performed at each study visit from a study site. The mfERG responses were grouped into three regions (central, middle and outer rings) and compared between the SNL and sham group. mfERG P1 response amplitude and implicit time. Data were collected from 50 subjects (26 in the SNL group, 24 in the sham group). At baseline, the P1 amplitudes of both the study eyes and the fellow eyes were similar between the groups at all rings. In the sham group, the P1 amplitude gradually decreased over time (P < .05). In the SNL group, there was an improvement in P1 amplitude which became statistically significant at the 36-month visit, detected in both the treated and fellow eyes at the central (P = .005) and middle ring (P = .007) but not at the outer ring (P = .070). No difference in P1 implicit time detected between the groups (P > .05). SNL treatment improved electro-physiological function. mfERG could be useful for monitoring AMD progression and evaluating the efficacy of SNL treatment.

Subthreshold yellow laser for fovea-involving diabetic macular edema in a series of patients with good vision: effectiveness and safety of a fovea-sparing technique

PurposePatients with center-involved diabetic macular edema (CI-DME) with good visual acuity (VA) represent a controversial clinical scenario in which a subthreshold laser might be a reasonable approach. We report a case series of patients with CI-DME with VA better than 20/32 who were treated with a subthreshold 577 nm (yellow) laser.MethodsThe area of retinal thickening on OCT was treated with confluent laser spots at individually titrated power. The fovea was spared from treatment. Effectiveness and safety were evaluated through OCT and autofluorescence (AF) as well as BCVA.ResultsA total of 23 eyes from 19 patients were treated. VA ranged from 20/20 to 20/30. The follow-up period ranged from 6 to 18 months. Edema in OCT resolved completely at the end of follow-up in 56.5% (13/23) of the cases. Central retinal thickness was reduced at 12 weeks and at the end of follow-up, with a mean reduction of 16.9 μm and 22 μm, respectively (paired t-test p = 0.001 and 0.0003). VA remained stable. The laser was invisible (OCT, AF, Fundoscopy) in 91,3% (21/23) of eyes.ConclusionsA fovea-sparing yellow subthreshold laser was safe and effective for treating CI-DME patients with good VA in this case series. This technique is of interest to prevent the progression of mild edema and might avoid or reduce the use of more invasive and expensive therapies. Excluding the fovea from the treated area does not seem to affect the results, which is of interest to novel laser practitioners.

Efficacy of nanosecond laser treatment in central serous chorioretinopathy with and without atrophy of retinal pigment epithelium

BackgroundTo evaluate the outcomes of subthreshold nanosecond laser treatment of chronic central serous chorioretinopathy (CSC) as a function of the severity of concomitant of retinal pigment epithelium (RPE) defects.MethodsThis retrospective study compares data from 23 CSC diagnosed eyes with only mild RPE defects (group 1), 16 CSC eyes with moderate RPE defects (group 2), and 17 CSC eyes having severe RPE defects (group 3). After subthreshold treatment with the standard Ellex 2RT™ nanosecond laser (Ellex Medical Lasers Ltd, Australia), changes in macular structure and levels of subretinal fluid (SRF) were assessed by OCT-SD, OCT-A, functional integrity of the retina was assessed by corrected distance visual acuity (CDVA) and microperimetry, each at baseline and 1, 3, 6, and 12 months after initial treatment; re-treatment took place in cases of persistent SRF pro re nata.ResultsDuring the 12 months observation period, group 1 and 2 mostly required on initial and one re-treatment (1.9 ± 1.0 treatments; 1.9 ± 1.3 treatments). In contrast, group 3 was subject to three to four treatments (3.7 ± 1.5 treatments). 6 to 12 months after treatment, subretinal fluid (SRF) disappeared in 100% of the eyes of group 1 and in 76.9%, and 42.9% of the eyes of group 2 and group 3, respectively. Retinal sensitivity and CDVA improved in group 1 and 2, but did not change significantly in group 3 during the 12 months period.ConclusionsSubthreshold nanosecond laser treatment is an effective and safe method for the restoration of macular anatomy and sensitivity in acute and chronic CSC cases with only mild or moderate RPE defects. However, this laser treatment has very limited outcome in CSC eyes with more severe RPE defects.

Laser treatment in retinitis pigmentosa-a review.

Retinitis pigmentosa (RP) is a common inherited retinal disease for which effective treatment is not yet known. This review sought to analyze the available medical literature covering the efficacy of different forms of laser treatment for RP in laboratory and clinical trials. The PubMed database was searched using the following phrases: "laser photocoagulation", "subthreshold laser", "nanolaser", "micropulse laser", "retinitis pigmentosa", "rod-cone dystrophy", and "retinal dystrophy". Results were stratified as clinical or experimental studies. Six studies involving animal models and three studies involving human subjects that examined laser treatment in RP were found. Laboratory studies on rodents favored classic laser photocoagulation as the most effective therapy for slowing the progression of proto-oncogene tyrosine-protein kinase MER-related RP. Two clinical studies on humans suggested transient but robust functional benefits of subthreshold micropulse laser treatment in RP. The available material is too scarce to define laser treatment as a standard procedure to treat RP in humans. Nondamaging retinal laser therapy should be tested more intensively in clinical trials as there is no proven negative side effect of that treatment and the theoretical background, especially the chaperone and reparative roles of heat shock proteins elicited during the procedure, supports this form of RP management.

Subthreshold Micro-Pulse Yellow Laser and Eplerenone Drug Therapy in Chronic Central Serous Chorio-Retinopathy Patients: A Comparative Study

ABSTRACT Purpose To study the outcomes of subthreshold micropulse yellow laser (SML) and eplerenone (EP) therapy in central serous chorio-retinopathy (cCSCR) Methods Retrospective study of 28 eyes of 27 patients undergoing SML and 20 eyes of 19 patients undergoing EP therapy Results Median duration of follow-up was 8 months for SML and 4.5 months for EP group. Complete SRF resolution was seen in 12/28 (42.8%) eyes in SML and 4/20 (20%) in EP group. Six eyes in SML group and two eyes in EP group needed additional SML. No EP patients demonstrated hyperkalemia warranting stopping of therapy. Baseline visual acuity (VA) was correlated positively with final VA in both groups. Presence/absence of focal leaks had differing outcomes in both treatment groups in terms of anatomical resolution. Conclusion Both treatment modalities were effective in the management of cCSCR showing comparable favorable anatomical outcomes, but visual outcomes were not significant, probably due to chronicity of the pathology.

Comparison of Subthreshold 577 and 810 nm Micropulse Laser Effects on Heat-Shock Protein Activation Kinetics: Implications for Treatment Efficacy and Safety.

PurposeTo compare the safety and efficacy of 810 versus 577 nm laser wavelengths for micropulse subthreshold (sublethal) laser treatment by mathematical analysis.MethodsTwo different representative laser parameter sets for micropulsed subthreshold diode laser treatment, one employing 810 nm and the other 577 nm, are compared with regard to efficacy by analysis of the kinetics of laser-induced heat-shock protein (HSP) activation; and for safety, by scaling law analysis.ResultsKinetics analysis of laser-induced HSP activation shows that the primary therapeutic effect of laser is thermal incitement of a long-term wavelength-independent increase in the rate of HSP-mediated protein repair specific to sick and dysfunctional cells, rather than from short-term increases in free intracellular HSP concentrations. Scaling law analysis of the same 810 and 577 nm laser parameters, however, finds treatment safety highly wavelength-sensitive, favoring 810 over 577 nm.ConclusionsMathematical analyses of the effects retinal laser-induced HSP activation provide important insights into the mechanism of action and the importance of wavelength selection in modern retinal laser therapy. Our analyses find 810 and 577 nm to be equally effective, but 810 nm having a significantly wider therapeutic range/safety margin, and thus less likely to cause inadvertent, and thus unpredictable, laser-induced retinal damage, than 577 nm.Translational RelevanceMathematical analysis of enzyme reaction kinetics provides important insights into the mechanism of action and clinical implications of wavelength selection in modern retinal laser therapy.

The Role of Subthreshold Micropulse Yellow Laser as an Alternative Option for the Treatment of Refractory Postoperative Cystoid Macular Edema.

Background: To evaluate the efficacy and the safety of subthreshold micropulse yellow laser (SMYL) in the treatment of chronic postoperative cystoid macular edema (PCME), which is refractory to standard therapies. Methods: A retrospective chart review of ten eyes of ten patients affected by refractory PCME who underwent SMYL was performed. Five PCME cases were subsequent to uncomplicated cataract surgery (CS), two cases to complicated CS (CCS) with posterior capsule rupture and three cases occurred after retinal detachment surgery (RD). All conditions were refractory to conventional treatments prior to SMYL interventions for at least 4 months, including nonsteroidal anti-inflammatory eyedrops, topical steroids, oral indomethacin, sub-Tenon’s triamcinolone injections and Dexamethasone intravitreal implants. All patients underwent one or more treatments with 577 nm SMYL photo-stimulation, with 7 × 7 grids with confluent spots and a 5% duty cycle covering the whole edematous retina, including the foveal center. Best corrected visual acuity (BCVA) and central macular thickness (CMT) were obtained using OCT, and evaluated before and after the treatment at 1, 2, 3 and 6-month follow-ups. Results: A complete subfoveal macular edema resolution was observed in all of the eyes, with statistically significant improvements in terms of BCVA and CMT in all of the follow-up timelines (at 6 months, p = 0.002 and p = 0.005, respectively). The mean number of laser treatments was 1.3. At the final follow-up, a complete subfoveal edema reabsorption was observed in all patients with visual acuity improvement. No complications were observed in any case. Conclusions: SMYL seems to be a safe and effective treatment for the long-term resolution of refractory PCME and may be a useful alternative to expensive and invasive therapeutic options.

Acute and Recurrent Central Serous Chorioretinopathy: Signs, Diagnosis, and Treatment

Acute central serous chorioretinopathy is an idiopathic disease characterized by a well-bordered neurosensorial retinal detachment localized mostly to the posterior pole. Though mostly having a benign clinical course, there can be recurrences and chronicity in the long run. Its pathogenesis remains to be obscure but choroidal hyperpermeability and a defect through the retinal pigment epithelium can be the cause.No treatment is generally required in patients with acute type of disease. However, medical therapy, thermal laser, photodynamic therapy, intravitreal injections, and subthreshold laser can be administered in some patients.

&lt;p&gt;The Evolving Treatment of Diabetic Retinopathy&lt;/p&gt;

PurposeTo review the current therapeutic options for the management of diabetic retinopathy (DR) and diabetic macular edema (DME) and examine the evidence for integration of laser and pharmacotherapy.MethodsA review of the PubMed database was performed using the search terms diabetic retinopathy, diabetic macular edema, neovascularization, laser photocoagulation, intravitreal injection, vascular endothelial growth factor (VEGF), vitrectomy, pars plana vitreous surgery, antiangiogenic therapy. With additional cross-referencing, this yielded 835 publications of which 301 were selected based on content and relevance.ResultsMany recent studies have evaluated the pharmacological, laser and surgical therapeutic strategies for the treatment and prevention of DR and DME. Several newer diagnostic systems such as optical coherence tomography (OCT), microperimetry, and multifocal electroretinography (mfERG) are also assisting in further refinements in the staging and classification of DR and DME. Pharmacological therapies for both DR and DME include both systemic and ocular agents. Systemic agents that promote intensive glycemic control, control of dyslipidemia and antagonists of the renin-angiotensin system demonstrate beneficial effects for both DR and DME. Ocular therapies include anti-VEGF agents, corticosteroids and nonsteroidal anti-inflammatory drugs. Laser therapy, both as panretinal and focal or grid applications continue to be employed in management of DR and DME. Refinements in laser devices have yielded more tissue-sparing (subthreshold) modes in which many of the benefits of conventional continuous wave (CW) lasers can be obtained without the adverse side effects. Recent attempts to lessen the burden of anti-VEGF injections by integrating laser therapy have met with mixed results. Increasingly, vitreoretinal surgical techniques are employed for less advanced stages of DR and DME. The development and use of smaller gauge instrumentation and advanced anesthesia agents have been associated with a trend toward earlier surgical intervention for diabetic retinopathy. Several novel drug delivery strategies are currently being examined with the goal of decreasing the therapeutic burden of monthly intravitreal injections. These fall into one of the five categories: non-biodegradable polymeric drug delivery systems, biodegradable polymeric drug delivery systems, nanoparticle-based drug delivery systems, ocular injection devices and with sustained release refillable devices. At present, there remains no one single strategy for the management of the particular stages of DR and DME as there are many options that have not been rigorously tested through large, randomized, controlled clinical trials.ConclusionPharmacotherapy, both ocular and systemic, will be the primary mode of intervention in the management of DR and DME in many cases when cost and treatment burden are less constrained. Conventional laser therapy has become a secondary intervention in these instances, but remains a first-line option when cost and treatment burden are more constrained. Results with subthreshold laser appear promising but will require more rigorous study to establish its role as adjunctive therapy. Evidence to support an optimal integration of the various treatment options is lacking. Central to the widespread adoption of any therapeutic regimen for DR and DME is substantiation of safety, efficacy, and cost-effectiveness by a body of sound clinical trials.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY CHANGES AFTER SUBTHRESHOLD MICROPULSE YELLOW LASER IN DIABETIC MACULAR EDEMA.

To assess changes on optical coherence tomography (OCT) angiography in diabetic macular edema (DME) treated with subthreshold micropulse yellow laser (SMPL) over a period of 6 months. Thirty-five eyes (35 consecutive patients) with treatment-naive DME prospectively underwent (at baseline, 3 and 6 months) best-corrected visual acuity, swept-source OCT angiography/OCT, and fundus autofluorescence. Following parameters were evaluated on OCT angiography in the superficial capillary plexus (SCP) and deep capillary plexus (DCP): the area of foveal avascular zone, number of microaneurysms (MA), area of cysts, and presence of capillary network alterations. Microaneurysm change was also evaluated in 15 fellow eyes, not needing treatment over 6 months. Vessel and perfusion densities were evaluated in the SCP, DCP, and choriocapillaris, with image J. Retina thickness, number of hyperreflective retinal spots, and external limiting membrane integrity were evaluated on OCT. All measurements were performed by two masked graders, independently. All patients had diabetes mellitus Type 2 (mean age, 69.4 ± 10.9 years; duration of diabetes mellitus, 15.7 ± 8.7 years; and HbA1c 7.7 ± 1.2%). Mean best-corrected visual acuity at baseline was 69.7 ± 12.0 letters ETDRS, 72.7 ± 10.7 at 3 months (gain 3.1 ± 4.3, P = 0.0049) and 74.3 ± 9.5 at 6 months (gain 4.6 ± 7.2, P < 0.0001). Foveal avascular zone area decreased in the DCP at 6 months (P = 0.01). Area of cysts decreased in the SCP at 3 months and 6 months (P = 0.038; P = 0.049), and in the DCP at 6 months (P = 0.0071). Number of MA decreased at 6 months in the SCP (P = 0.0007) and at 3 months and 6 months in the DCP (P = 0.048; P < 0.0001) in treated eyes. No significant change in number of MA was found in nontreated eyes. There was no statistically significant change in any other OCT angiography/OCT parameter. Subthreshold micropulse yellow laser induces more pronounced changes in the DCP than in the SCP in DME. These changes occurred as early as 3 months after treatment. The evaluation of specific parameters in the DCP may help in determining treatment response.

Commentary: Subthreshold micropulse yellow laser in diabetic macular edema.

Commentary: Subthreshold micropulse yellow laser in diabetic macular edema.

Subthreshold laser compared to spironolactone in treatment of chronic central serous retinopathy

AbstractPurposeTo compare clinical and morphological outcomes of Subthreshold Laser and Spirolonactone in treatment of chronic central serous retinopathy (CSR).MethodsPatients with chronic CSR (visual symptoms &gt; 6 months) treated either with Subthreshold Laser or Spirolonactone were recruited. Patients data were recorded at four time points: at initiation of treatment, at 1 month, at 3 months and at the last follow up possible. Main outcome measures included best‐corrected visual acuity (BCVA), central macular thickness (CMT), location and height of subretinal fluid (SRF), degree of photoreceptors outer segments (POS) damage, presence of pigmented epithelium detachment (PED), integrity of retinal pigmented epithelium (RPE).ResultsForty‐seven eyes of 45 patients and 45 eyes of 42 patients were included in the Subthreshold Laser and Spirolonactone groups, respectively. Mean number of sessions of Subthreshold Laser per patient was 1.36 ± 0.5, while mean number of Spirolonactone cycles was 1.66 ± 1.0. In patients undergoing Subthreshold Laser, BCVA did not significantly improve at all timepoints, while patients undergoing Spirolonactone showed increased visual acuity in the long term (p = 0.011), but not at 1 month and at 3 months. Both Subthreshold Laser and Spirolonactone significantly improved CMT, CFT, SRF at all timepoints (all p &lt; 0.05). Spirolonactone allowed a significantly higher CMT and SRF decrease compared to Subthreshold Laser at 3 months (p = 0.048 and 0.036, respectively). Spirolonactone side effects occured in 5 patients (11%), while none of patients in the Subthreshold Laser group developed RPE atrophy.ConclusionsTreatments with Subthreshold Laser and Spirolonactone are effective in fluid reduction at every time point in chronic CSR, while not giving substantial improvement in visual acuity at 1 month and at 3 months. Spirolonactone allows a significantly higher visual recovery in the long term, while allowing a significantly higher fluid reabsorption at 3 months compared to Subthreshold Laser.

Nanosecond Laser Treatment in Chorioretinopathia Centralis Serosa without RPE Defects: A Retrospective Case Series

Chorioretinopathia centralis serosa (CCS) is a uni- or bilateral disease of the macula which is characterized by detachment of the neuro-sensory retina. The spontaneous resolution rate is 68% after four months and 84% after six months. To investigate the efficacy of subthreshold nanopulse laser treatment for central serous chorioretinopathy (CCS) in the absence of any atrophy in the retinal pigment epithelium (RPE). This retrospective study comprised 23 eyes of 23patients without previous treatment. Patients were followed up to 12 months. Laser treatment was performed with the 2RT® nanolaser using a grid stimulation. Changes in corrected visual acuity (VA), microperimetry and subretinal fluid height in optical coherence tomographic images were measured. Saliences in autofluorescence images and angiographic images were observed. All results were documented 1, 3, 6 and 12 months after the first treatment. Patients did not receive any supplementary treatment. Two months after the first treatment, 74% of the patients showed complete SRF resolution and 91% of the patients within 6 months had complete resorption of the SRF. Central visual acuity and macula sensitivity significantly improved from 0.18 ± 0.16 logMAR to 0.09 ± 0.17 logMAR and 24.19 ± 3.96 dB to 27.59 ± 2.89 dB. The SRF decreased within one month significantly. No CNV was documented during the observation time. The baseline subretinal fluid height is a predictive factor of faster resolution. The evaluation of our treatment results shows that the therapy is a safe and promising method. Patients with a CCS without existing RPE defects benefit from the treatment with the 2RT® nanolaser, which is associated with an improvement of the macula function.

Subthreshold Laser Therapy for the Treatment of Refractory Diabetic Macular Edema: A Case Report

Subthreshold Laser Therapy for the Treatment of Refractory Diabetic Macular Edema: A Case Report

The change of retinal microstructure and the correlation with visual outcome in central serous chorioretinopathy after laser treatment

Objective To observe the change of retinal microstructures and the association between visual outcome with these microstructures in central serous chorioretinopathy (CSC) after laser treatment. Methods This is a retrospective study. From April 2016 to February 2017, a total of 52 eyes from 52 patients who underwent conventional laser treatment (27 eyes) or subthreshold laser treatment (25 eyes) for CSC and the sub-retinal fluid (SRF) absorbed completely were included in this study. The were 46 patients (46 eyes) and 6 males (6 eyes), with the mean age of 43.92±8.62 years. The healthy fellow eyes (49 eyes) were selected as control. All patients were underwent BCVA and SD-OCT examination. According to the OCT images for all patients, the thickness of central foveal (CFT), outer nuclear (ONL), inner segment (IS), outer segment (OS) were measured. The status of ellipsoid zone (EZ), interdigitation zone (IZ) and RPE were also evaluated at fovea. Comparing the change of SD-OCT microstructures in two time points, the first visit after SRF absorbed and the last visit respectively. Spearman correlation analysis was used to analyze the relation between BCVA and ONL, IS, OS. Results At the first visit after SRF absorbed, compared with control eyes, the thickness of CFT (182.55±24.14 μm), ONL (72.86±17.39 μm), IS (41.23±5.14 μm), OS (18.52±10.26 μm) in CSC eyes were decreased (P<0.001). Meanwhile, the mean BCVA of CSC eyes was 81.27±6.39 letters, which was also significantly decreased comparing with control eyes (P<0.001). At last visit, the thickness of CFT, ONL, IS, OS were 195.19±22.10, 75.44±16.33, 44.56±4.09, 26.60±11.39 μm, and the mean BCVA was 85.50±5.95 letters. All recovered significantly comparing with first visit (P<0.05). At first visit, the BCVA of patients with integrate EZ (83.38±5.78 letters) was significantly better than the BCVA of patients with unintegrated EZ (77.90±5.97 letters) (P=0.003). And the BCVA of patients with smooth RPE (82.72±5.95 letter) was also significantly better than the BCVA of patients with rough RPE (78.00±6.31 letters) (P=0.020). The result of Spearman correlation analysis showed that the thickness of OS was positively correlated to BCVA at two time points (r=0.423, 0.416; P=0.002, 0.002). Conclusions In CSC, the thickness of ONL, IS, OS were decreased, and the integrality of EZ, IZ, the smooth of RPE were disrupted in different extent. After laser treatment, with retinal reattachment, those microstructures including ONL, IS, OS, EZ, IZ recovered slowly. The thickness of OS, the integrality of EZ and the smooth of RPE were associated with visual acuity. Key words: Central serous chorioretinopathy; Laser coagulation; Tomography; optical coherence

Secondary and Exploratory Outcomes of the Subthreshold Nanosecond Laser Intervention Randomized Trial in Age-Related Macular Degeneration: A LEAD Study Report

To evaluate the secondary and exploratory outcomes of the Laser Intervention in Early Stages of Age-Related Macular Degeneration (LEAD) study, a 36-month trial of a subthreshold nanosecond laser (SNL) treatment for slowing the progression to late age-related macular degeneration (AMD) in its early stages. Multicenter, randomized, sham-controlled trial. Two-hundred ninety-two patients with bilateral large drusen. Participants were randomly assigned to receive SNL or sham treatment to the study eye at 6-month intervals. The secondary outcome measure of the LEAD study was the time to development of late AMD, defined by multimodal imaging in the non-study eye. The exploratory outcome measures were the rate of change in best-corrected visual acuity (BCVA), low-luminance visual acuity, microperimetric mean sensitivity, drusen volume in the study and non-study eyes, and participant-reported outcomes based on the Night Vision Questionnaire and Impact of Vision Impairment questionnaire. Progression to late AMD in the non-study eye was not significantly delayed with SNL treatment (hazard ratio, 0.83; 95% confidence interval, 0.40-1.71; P= 0.611). There was no evidence of effect modification based on the coexistence of reticular pseudodrusen; interaction P= 0.065). There was no significant difference between study groups in the rate of change of low-luminance visual acuity, microperimetric mean sensitivity, and drusen volume in the study or non-study eyes, and Night Vision Questionnaire and Impact of Vision Impairment questionnaire scores (all P ≥ 0.167). The rate of BCVA decline was slightly higher for participants in the SNL group compared with the sham treatment group in the study eye (-0.54 and 0.23 letters/year, respectively; P < 0.001) but not the non-study eye (-0.48 and -0.56 letters/year, respectively; P= 0.628). Subthreshold nanosecond laser treatment of one eye did not have an effect on delaying progression to late AMD in the fellow eye and did not, in general, have an impact on the exploratory structural, functional, and participant-reported outcomes.

Surface engineering of magnetic and mechanical properties of Ta/Pt/GdFeCo/IrMn/Pt heterostructures by femtosecond laser pulses

Irradiation of the heterostructure glass/Ta/Pt/GdFeCo/IrMn/Pt by 50 fs ultra-short laser pulses causes local thinning of the film down to ~12–30 nm depth. These pits are distinguished by Atomic Force Microscopy (AFM), while their stray magnetic fields were detected by Magnetic Force Microscopy (MFM). The crater was formed due to layer- by -layer evaporation of the material. No sign of melting was found in the vicinity of the crater at subthreshold laser fluence below 12–15 mJ/cm2, but exceeding of the threshold caused destruction of the layers. Energy-dispersive X-ray spectroscopy (EDX) revealed depletion of Gd, Fe and Co, responsible for magnetic properties of the subthreshold crater. The amplitude of the local MOKE signal decreased down to 1.7 times in the irradiated area, while thinning of the ferromagnetic layer was 1.1 times. No proportional change of magnetization was caused by bias effect of IrMn layer. Decreased elastic modulus was found inside the subthreshold crater in the irradiated areas. Laser engineering of the surface of GdFeCo thin films opens the way for local control of energy balance between magnetic anisotropy, exchange coupling and Zeeman energy and creation of separated sectors for capture, storage and analysis of the ferromagnetic nanoparticles.

Colossal laser ablation threshold of Ge crystal due to formation of GeO2 nanolayer: “Lid Effect” - Subsurface boiling mechanism

Colossally increased laser ablation threshold intensity Ith = 637.0 MW/cm2 of mechanically polished Ge crystal was found. It exceeds by factor of 100 that of chemically etched Ge single crystal (1 0 0), which is about 6.0 MW/cm2. This phenomenon is related to the formation of thin GeO2 layer during the action of laser pulse (wavelength λ = 1064 nm, pulse duration 6 ns, energy in a pulse W = 0.12 J, repetition rate of 10 Hz and beam diameter 2 mm) on the mechanically polished amorphous α-Ge. The increased threshold intensity is explained by the “lid effect”- a non-monotonous temperature distribution with maximum in the bulk of the crystal, where melting and even boiling of material takes place under a solid GeO2 nanolayer, preventing the ablation at a much lower intensity. Applying SEM and optical microscope methods, appearance of bubbles at the irradiated surface was observed. In experiments, the fundamental frequency of pulsed Nd:YAG laser in the regime of multi-pulse irradiation of the same surface spot was used. The thickness of GeO2 layer, estimated from SEM images and by the use of Casino simulation software, is up to 50 nm. According to our calculations of temperature field in GeO2/Ge structure, the maximum of temperature is located near the interface and Ge boiling temperature is reached under solid GeO2 layer at a sub-threshold laser intensity. The theoretical and experimental results are thus explained by the subsurface boiling mechanism of laser ablation in GeO2/Ge structure in the presence of solid GeO2 layer, acting as a “lid”. The possible applications of the investigation results are proposed.