Clinical applications of the MicroPulse diode laser

Central serous chorioretinopathy: An evidence-based treatment guideline

Central serous chorioretinopathy (CSC) is a relatively common disease that causes vision loss due to macular subretinal fluid leakage and it is often associated with reduced vision-related quality of life. In CSC, the leakage of subretinal fluid through defects in the retinal pigment epithelial layer's outer blood-retina barrier appears to occur secondary to choroidal abnormalities and dysfunction. The treatment of CSC is currently the subject of controversy, although recent data obtained from several large randomized controlled trials provide a wealth of new information that can be used to establish a treatment algorithm. Here, we provide a comprehensive overview of our current understanding regarding the pathogenesis of CSC, current therapeutic strategies, and an evidence-based treatment guideline for CSC. In acute CSC, treatment can often be deferred for up to 3-4 months after diagnosis; however, early treatment with either half-dose or half-fluence photodynamic therapy (PDT) with the photosensitive dye verteporfin may be beneficial in selected cases. In chronic CSC, half-dose or half-fluence PDT, which targets the abnormal choroid, should be considered the preferred treatment. If PDT is unavailable, chronic CSC with focal, non-central leakage on angiography may be treated using conventional laser photocoagulation. CSC with concurrent macular neovascularization should be treated with half-dose/half-fluence PDT and/or intravitreal injections of an anti-vascular endothelial growth factor compound. Given the current shortage of verteporfin and the paucity of evidence supporting the efficacy of other treatment options, future studies-ideally, well-designed randomized controlled trials-are needed in order to evaluate new treatment options for CSC.

Comparing Half-Dose Photodynamic Therapy with Subthreshold Micropulse Laser for the Treatment of Central Serous Chorioretinopathy

PURPOSE

To compare the anatomic and functional outcomes of half-dose photodynamic therapy (PDT) and yellow 577-nm subthreshold micropulse laser (SMLT) in treating patients with chronic central serous chorioretinopathy (CSCR).

DESIGN

Prospective, double-masked, randomized, controlled clinical trial.

PARTICIPANTS

Patients with chronic CSCR confirmed by clinical features and multimodal imaging.

METHODS

Eligible patients were randomized (1:1) to receive half-dose PDT or SMLT. The same treatment was repeated if persistent subretinal fluid (SRF) was observed. Treatment responses were evaluated 1 month after treatment and every 3 months until the end point at 12 months.

MAIN OUTCOME MEASURES

The primary outcome measure was the complete resolution of SRF on OCT scan at month 12. Secondary outcomes included the changes in best-corrected visual acuity (BCVA), central macular thickness (CMT) as measured by OCT, retinal sensitivity as measured by microperimetry, and vision-related quality of life using the National Eye Institute 25-Item Visual Function Questionnaire.

RESULTS

Between April 2017 and October 2020, 68 patients were recruited. At 1 month after treatment, SRF resolved in 8 (24.2%) of 33 patients receiving SMLT and in 20 (58.8%) of 34 patients receiving half-dose PDT. This increased to 23 (82.1%) of 28 patients in the SMLT group and 30 (90.9%) of 33 patients in the half-dose PDT group at 12 months of follow-up. Kaplan-Meier survival curves showed significantly faster resolution of SRF in the half-dose PDT group than the SMLT group (P = 0.016). Both groups showed significant improvement in BCVA (-0.12 ± 0.21, P = 0.005 for SMLT; -0.13 ± 0.12, P < 0.001 for half-dose PDT), CMT (-154.2 ± 105.6, P < 0.001 for SMLT; -140.8 ± 94.0, P < 0.001 for half-dose PDT), and retinal sensitivity (5.70 ± 5.02, P < 0.001 for SMLT; 6.05 ± 3.83, P < 0.001 for half-dose PDT) at 12 months compared with baseline. There was no significant difference between the 2 treatment groups at each time point in all investigations except BCVA at 3 months (P = 0.03).

CONCLUSIONS

When comparing half-dose PDT to subthreshold SMLT, this study has shown both treatments to be viable options, with half-dose PDT achieving faster anatomic success and functional improvement.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Micropulse Laser Therapy as an Integral Part of Eye Disease Management

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

Current Treatments for Diabetic Macular Edema

Diabetic retinopathy is a major retinal disorder and a leading cause of blindness. Diabetic macular edema (DME) is an ocular complication in patients with diabetes, and it can impair vision significantly. DME is a disorder of the neurovascular system, and it causes obstructions of the retinal capillaries, damage of the blood vessels, and hyperpermeability due to the expression and action of vascular endothelial growth factor (VEGF). These changes result in hemorrhages and leakages of the serous components of blood that result in failures of the neurovascular units (NVUs). Persistent edema of the retina around the macula causes damage to the neural cells that constitute the NVUs resulting in diabetic neuropathy of the retina and a reduction in vision quality. The macular edema and NVU disorders can be monitored by optical coherence tomography (OCT). Neuronal cell death and axonal degeneration are irreversible, and their development can result in permanent visual loss. Treating the edema before these changes are detected in the OCT images is necessary for neuroprotection and maintenance of good vision. This review describes the effective treatments for the macular edema that are therefore neuroprotective.

Micropulse diode laser therapy in refractory glaucoma

Purpose

Description of safety and efficacy of micropulse Transscleral cyclophotocoagulation as a treatment option for refractory glaucoma.

Methods

This is a prospective study including 39 eyes of 31 patients followed for refractory glaucoma, who benefited from transscleral cyclophotocoagulation using a microplused laser. The main indication for the procedure was increased ocular pressure refractory to quadritherapy in various types of glaucoma. The patients were treated using iridex Cyclo G6 laser with a Micropulse P3 infrared probe with a wavelength of 810 ​nm. The parameters for the procedure were a duration of 90 ​s per hemisphere with a power of 2000 mW and an energy of 180 ​J. Both the upper and lower hemispheres were treated in the same procedure, sparing the 3 o'clock and 9 o'clock meridians, and all the patients benefited from a single treatment session. The following parameters were evaluated: ocular pain and overall tolerance; visual acuity; and the evolution of IOP postoperatively up to 9 months.

Results

The glaucoma subtypes treated are as follows: primary open-angle glaucoma (n ​= ​05), chronic angle-closure glaucoma (n ​= ​13), neovascular glaucoma (n ​= ​07), aphakic glaucoma (n ​= ​06), malignant glaucoma (n ​= ​04), post-traumatic angle recession (n ​= ​02), and inflammatory glaucoma (n ​= ​02). The mean pre-operative intraocular pressure was 42.3 ​± ​5.2 ​mmHg and the mean post-operative intraocular pressure at 9 months was 16.9 ​± ​1.9 ​mmHg. The reduction in IOP was 49.9%. The average number of intraocular pressure-lowering medications used prior to surgery was four, and the average number of medications used at the 9-month post-operative visit was 2.0 ​± ​1.2 (70.3% of patients were on dual therapy). The overall success rate was 60.5%.

Conclusions

Micropulse transscleral cyclophotocoagulation appears to be a safe and efficient treatment for refractory glaucoma. Its indications should therefore be broadened and proposed early in various situations.

Randomized clinical trial comparing intravitreal aflibercept combined with subthreshold laser to intravitreal aflibercept monotherapy for diabetic macular edema

To compare the efficacy and safety of intravitreal aflibercept with three loading doses + pro re nata regimen combined with subthreshold laser application to that of IVA monotherapy on eyes with diabetic macular edema. This was a phase 4 clinical trial with a prospective, randomized, and parallel investigator-driven protocol. Patients with DME were randomly assigned to the IVA monotherapy group (n = 25) or the IVA + SL combination therapy group (n = 26). The main outcome measures were the number of IVA injections and the changes in the best-corrected visual acuity (BCVA) and the central retinal thickness (CRT) at the final evaluation at 96 weeks. The mean number of IVA injections in the monotherapy group was 5.86 ± 2.43 and it was 6.05 ± 2.73 in the IVA + SL group at 96 weeks, and this difference was not significant (P = 0.83). The differences in the mean changes of the CRT (P = 0.17) and the BCVA (P = 0.31) were also not significant between the two groups throughout the follow-up period. We conclude that adjunct of SL to anti-VEGF therapy does not reduce the number of necessary intravitreal injections.

2-Jahres-Ergebnisse nach transskleraler MicroPulse-Lasertherapie bei Patienten mit primärem Offenwinkelglaukom

Hintergrund Untersuchung der langfristigen Effizienz und Sicherheit der transskleralen Lasertherapie (TLT) mittels MicroPulse über 24 Monate bei Patienten mit primärem Offenwinkelglaukom (POWG).

Material und Methoden In dieser prospektiven interventionellen Fallserie wurden die Daten von 44 Augen von medikamentös behandelten POWG-Patienten ausgewertet, die eine MicroPulse-TLT erhielten, um eine weitere Senkung des Augeninnendrucks (IOD) zu erreichen. Es wurden die Reduktion des 24-h-IODs, der zirkadianen IOD-Fluktuationen und der IOD-Spitzen nach 3, 12 und 24 Monaten untersucht. Zudem sollten postoperative Komplikationen, die Misserfolgsquote und Einflussfaktoren auf den Therapieerfolg analysiert werden.

Ergebnisse Der IOD ist von 16,1 ± 3,4 mmHg präoperativ auf 13,0 ± 2,9 mmHg (n = 31; p < 0,001) nach 3 Monaten, 12,3 ± 3,0 mmHg (n = 27; p < 0,001) nach 12 Monaten und 13,1 ± 2,6 mmHg (n = 23; p < 0,001) nach 24 Monaten gesunken. Nach 24 Monaten erreichten 23 Augen (52%) ihren individuellen Zieldruck. Es traten keine schwerwiegenden postoperativen Komplikationen auf. Es konnten keine Einflussfaktoren auf den Therapieerfolg identifiziert werden. Das häufigste Therapieversagen war innerhalb der ersten 3 postoperativen Monate zu beobachten und blieb danach nahezu stabil.

Schlussfolgerung Die MicroPulse-TLT zeigt eine gute IOD-Senkung bei Patienten mit primärem Offenwinkelglaukom und maximal tolerierter drucksenkender Lokaltherapie, wobei etwa 50% der Augen ihren individuellen Zieldruck erreichten.

Interferometric imaging of thermal expansion for temperature control in retinal laser therapy

Precise control of the temperature rise is a prerequisite for proper photothermal therapy. In retinal laser therapy, the heat deposition is primarily governed by the melanin concentration, which can significantly vary across the retina and from patient to patient. In this work, we present a method for determining the optical and thermal properties of layered materials, directly applicable to the retina, using low-energy laser heating and phase-resolved optical coherence tomography (pOCT). The method is demonstrated on a polymer-based tissue phantom heated with a laser pulse focused onto an absorbing layer buried below the phantom's surface. Using a line-scan spectral-domain pOCT, optical path length changes induced by the thermal expansion were extracted from sequential B-scans. The material properties were then determined by matching the optical path length changes to a thermo-mechanical model developed for fast computation. This method determined the absorption coefficient with a precision of 2.5% and the temperature rise with a precision of about 0.2°C from a single laser exposure, while the peak did not exceed 8°C during 1 ms pulse, which is well within the tissue safety range and significantly more precise than other methods.

An update on continuous-wave cyclophotocoagulation (CW-CPC) and micropulse transscleral laser treatment (MP-TLT) for adult and paediatric refractory glaucoma

PURPOSE

Continuous-wave cyclophotocoagulation (CW-CPC) is often preferred to medical and surgical treatments for managing refractory glaucoma. This review summarizes diode CW-CPC indications, history, histopathology, methods, efficacy and safety. It also provides an overview of the latest data available on micropulse transscleral laser treatment (MP-TLT) that uses repetitive micropulses of diode laser energy in an off-and-on cyclical fashion.

METHODS

A literature review was conducted on transscleral CW-CPC (CW-TSCPC), endoscopic CPC (ECP) and MP-TLT. Relevant series of adult and paediatric patients were included for assessing the procedures.

RESULTS

Regarding CW-TCPC, highly variable success rates are reported in the literature, depending on the definition of success, type of underlying glaucoma, energy settings, follow-up duration and retreatment rates. CW-CPC often needs to be repeated, especially in paediatric patients. CW-CPC exposes to risks of inflammation and chronic ocular hypotony or phthisis with irreversible visual loss. CW-TSCPC has mainly been used in very severe forms of glaucoma, in painful eyes with limited visual potential or after filtering surgery failure. Published data on ECP are more limited but overall good success rates have been reported. Through the direct visualization of the targeted ciliary body in anatomically abnormal eyes, ECP is the preferred surgical procedure in paediatric refractory glaucoma. Complication rates are relatively low after ECP; however, large studies with long-term follow-up are needed. ECP may be used in difficult, refractory cases, but it is often used earlier when combined with cataract surgery. Despite limited data on the exact mechanism of action of MP-TLT and a lack of standardization of laser settings, the first data from heterogeneous case series shows that it has a similar efficacy and a better safety profile compared to CW-TSCPC in the medium term.

CONCLUSION

Although they may lead to sight-threatening complications, both CW-TSCPC and ECP seem effective. ECP appears to be superior to CW-TSCPC in paediatric refractory glaucoma. Unlike ECP combined with cataract surgery, evidence supporting a wider use of CW-TSCPC and MP-TLT in earlier stages of neuropathy is lacking. While it now appears that the safety profile of MP-TLT is superior to that of CW-CPC, robust prospective comparative studies including homogeneous and well-defined cohorts of patients are still needed to confirm an at least comparable efficacy in the long term.

Optical dosimeter for selective retinal therapy based on multi-port fiber-optic interferometry

Selective retinal therapy (SRT) employs a micro-second short-pulse lasers to induce localized destruction of the targeted retinal structures with a pulse duration and power aimed at minimal damage to other healthy retinal cells. SRT has demonstrated a great promise in the treatment of retinal diseases, but pulse energy thresholds for effective SRT procedures should be determined precisely and in real time, as the thresholds could vary with disease status and patients. In this study, we present the use of a multi-port fiber-based interferometer (MFI) for highly sensitive real-time SRT monitoring. We exploit distinct phase differences among the fiber ports in the MFI to quantitatively measure localized fluctuations of complex-valued information during the SRT procedure. We evaluate several metrics that can be computed from the full complex-valued information and demonstrate that the complex contour integration is highly sensitive and most correlative to pulse energies, acoustic outputs, and cell deaths. The validity of our method was demonstrated on excised porcine retinas, with a sensitivity and specificity of 0.92 and 0.88, respectively, as compared with the results from a cell viability assay.

Long-term results (>1 year) in 19 dogs treated with MicroPulse transscleral diode cyclophotocoagulation for refractory glaucoma

OBJECTIVE

To report the long-term (>1 year) outcome of MicroPulse transscleral diode cyclophotocoagulation (MP-TSCP) in dogs.

ANIMALS STUDIED

Client owned dogs that underwent MP-TSCP at a veterinary referral center.

PROCEDURE

Retrospective study of 19 dogs treated with MP-TSCP. Dogs were evaluated at a median follow-up time of 30.5 months postoperatively. Reported outcomes were intraocular pressure (IOP), retention or loss of vision, number of medications, and additional procedures performed. Variables associated with time to treatment failure were evaluated.

RESULTS

Data from 19 dogs (24 eyes) was available. Median laser settings employed were 140 s and 2200 mW at 31.3% duty cycle. Long-term postoperative IOP was lower than preoperative IOP values (14 mmHg (IQR = 22 mmHg, range: 4-52 mmHg) versus 30 mmHg (IQR = 31 mmHg, range: 8-62 mmHg), respectively). Laser settings >2000 mW were associated with a significantly longer time to reported failure. MP-TSCP was the sole therapy performed in 16/24 eyes resulting in long-term IOP control in 13/24 eyes and retention of vision in 6 of the 14 sighted eyes. Repeat MP-TSCP was performed in 10/24 eyes. Eight of 24 eyes required additional procedures with long-term IOP control in 4/8 eyes.

CONCLUSIONS

MicroPulse transscleral diode cyclophotocoagulation can be an effective treatment for refractory glaucoma in select cases. Higher laser settings increased time to reported failure, whereas age, glaucoma type, and preoperative IOP did not affect survival. MP-TSCP as sole therapy or coupled with additional glaucoma procedures controlled the IOP in 70% of cases.

Micropulse trans-scleral laser therapy outcomes for uncontrolled glaucoma: a prospective 18-month study

OBJECTIVE

To evaluate the efficacy and safety of micropulse trans-scleral laser therapy (mTLT) in glaucomatous patients.

DESIGN

Prospective, interventional study in a university hospital setting.

PARTICIPANTS

Fifty-two eyes of 52 adult patients with uncontrolled glaucoma despite maximal tolerated medical treatment, and/or poor candidates for filtering surgery.

METHODS

Participants received a 360-degree mTLT diode laser treatment (2000mW, 31.33% duty cycle), with duration adjusted to iris pigmentation and glaucoma severity (160-320 seconds). They were followed for 18 months to assess intraocular pressure (IOP), number of medications, corrected distance visual acuity (CDVA), glaucoma progression based on Humphrey Sita 24-2 perimetry and Cirrus high-definition optical coherence tomography, and complications. The primary outcome measure was the absolute success at 18 months. Absolute success was defined as an IOP 6-21 mm Hg and at least 25% IOP reduction, with equal or less number of IOP medications. Qualified success allowed for an increased number of IOP medications. Failure was defined as an inability to meet the criteria for success or the need for incisional glaucoma surgery.

RESULTS

Treatment absolute success was 61.5% at 12 months and 59.6% at 18 months. Mean IOP was reduced by 35.6% at 18 months (23.6 ± 6.5 mm Hg at baseline; 15.2 ± 4.1 mm Hg at 18 months, p < 0.001). mTLT did not significantly reduce the number of topical glaucoma medications (p = 0.075); however, 15 eyes (29%) had systemic oral glaucoma treatment at baseline and 10 eyes (20%) at 18 months. Eight patients (15%) experienced vision loss of ≥2 lines after the procedure. Three patients (6%) regained their preoperative CDVA by 1 month, and 3 patients (6%) by 3 months, while 2 patients (4%) sustained persistent visual loss. No ocular complications were noted in 84.6%. Incisional surgery was required in 25% of eyes owing to inadequately controlled glaucoma despite mTLT.

CONCLUSIONS

mTLT is a good therapeutic option for moderate IOP reduction, while being safe and predictable. This improved safety profile makes mTLT a treatment to be considered earlier in the management of glaucoma.

One-Year Follow-up of Pars Plicata Versus Pars Plana Application of Transscleral Micropulse Cyclophotocoagulation

PURPOSE

To compare the efficacy and safety of micropulse transscleral cyclophotocoagulation applied at the level of the pars plicata transscleral micropulse cyclophotocoagulation (PLI-MPC) versus the pars plana transscleral micropulse cyclophotocoagulation (PLA-MPC).

METHODS

This prospective interventional case series included 44 eyes of 31 medically treated primary open-angle glaucoma patients scheduled for micropulse transscleral cyclophotocoagulation to achieve further intraocular pressure (IOP) reduction. In total, 22 eyes underwent PLI-MPC and PLA-MPC each. Primary endpoints were the reduction of 24-hour mean diurnal IOP (mean of 6 measurements), diurnal IOP fluctuations, and peak IOP, after 3 and 12 months. Secondary outcomes were postoperative complications, a possible deterioration in visual acuity and field, factors influencing IOP reduction, and the number of dropouts.

RESULTS

In the PLI-MPC group, IOP was reduced from 15.9±3.4 mm Hg to 13.6±3.1 mm Hg (n=16; P<0.001) and 12.9±3.7 mm Hg (n=13; P<0.001) at 3 and 12-month follow-up. In the PLA-MPC group, IOP decreased from 16.4±3.5 mm Hg to 12.3±2.6 mm Hg (n=15; P<0.001) and 11.8±2.2 mm Hg (n=14; P<0.001), respectively. At 12 months, 59% of the PLI-MPC and 63% of the PLA-MPC group had a sufficient IOP reduction to reach the individual target pressure. No complications were seen in either group. A higher preoperative IOP was recognized as the only factor influencing the postoperative IOP reduction.

CONCLUSIONS

PLI-MPC and PLA-MPC seem to be safe and effective in further lowering the IOP in about 60% of patients with primary open-angle glaucoma who did not reach target pressure despite maximally tolerated IOP-lowering medication. Although the IOP-lowering effect was not statistically significantly different between groups the pars plicata application was superior and easier to perform and should be recommended as the preferred method of application.

The effect of various media and probe angles on the power output of the Cyclo G6 Glaucoma Laser System

To evaluate the effect of various media and Iridex MicroPulse P3 (MP3) probe angles on the power output from the Cyclo G6 Glaucoma Laser (G6) System. A laser power meter was used to measure the power output (milliwatts, mW) of the Cyclo G6 System. Each of the ten trials consisted of measurements in six different media: no substrate, balanced salt solution (BSS), artificial tears (AT), tetracaine eye drop, lubricating ointment, and lidocaine gel. The output of the MP3 probe was measured at an angle of 90° and 45°, submerged in the respective media. The output was also measured with the probe held at 90° but above the medium. The mean power outputs with the probe being held at 90° to the sensor with no substrate, BSS, AT, tetracaine eye drop, lubricating ointment, and lidocaine gel were 358 ± 16.8 mW, 612 ± 14.2 mW, 613 ± 13.3 mW, 612 ± 14.0 mW, 620 ± 9.9 mW, and 610 ± 12.2 mW, respectively. These values were statistically higher than noncontact and 45° probe angles for each medium. The values between any two media (excluding no substrate) at a 90° probe angle with full contact were not statistically significant. The highest output of the G6 System was obtained with a 90° probe angle, with full contact and any of the coupling media.

Outcomes of micropulse transscleral cyclophotocoagulation in primary open-angle glaucoma, pseudoexfoliation glaucoma, and secondary glaucoma

PURPOSE

The aim of this study is to compare the outcomes of micropulse transscleral cyclophotocoagulation between primary open-angle glaucoma, pseudoexfoliation glaucoma, and other types of secondary glaucoma.

METHODS

Outcomes of 96 consecutive patients with refractory, end-stage glaucoma treated with micropulse transscleral cyclophotocoagulation were retrospectively reviewed. Follow-up examinations were performed on a regular basis until 12 months postoperatively. Surgical successes were defined as maintaining intraocular pressure ⩽18 mmHg and ⩾20% reduction in intraocular pressure (criteria A), ⩽15 mmHg intraocular pressure and ⩾25% reduction in intraocular pressure (criteria B), and ⩽12 mmHg intraocular pressure and ⩾30% reduction in intraocular pressure from baseline (criteria C).

RESULTS

Ninety-six eyes of 96 patients (50 (52%) females, 46 (48%) males) were included. Among all eyes, 32 were primary open-angle glaucoma, 30 were pseudoexfoliation glaucoma, and 34 were other types of secondary glaucoma. The mean age was 59.37 ± 11.45 (range: 20-91) years. The mean follow-up period was 14.2 ± 3.9 (range: 12-16) months. At 12 months, the success rates of primary open-angle glaucoma, pseudoexfoliation glaucoma, and secondary glaucoma group were 68.75%, 66.6%, and 64.7% (p = 0.185) for criteria A; 56.25%, 53.3%, and 50% (p = 0.153) for criteria B; and 43.75%, 43.3%, and 38.2% (p = 0.146) for criteria C. Four patients (12.5%) in primary open-angle glaucoma group, 5 patients (16.6%) in pseudoexfoliation glaucoma group, and 14 (41.2%) patients in other secondary glaucoma group required reoperation during the follow-up (p < 0.05).

CONCLUSION

Micropulse transscleral cyclophotocoagulation is an equally effective method of lowering intraocular pressure in patients with primary open-angle glaucoma, pseudoexfoliation glaucoma, and other types of secondary glaucoma. The rate of reoperation was higher in refractory secondary glaucoma patients.

Central serous chorioretinopathy: Towards an evidence-based treatment guideline

Central serous chorioretinopathy (CSC) is a common cause of central vision loss, primarily affecting men 20-60 years of age. To date, no consensus has been reached regarding the classification of CSC, and a wide variety of interventions have been proposed, reflecting the controversy associated with treating this disease. The recent publication of appropriately powered randomised controlled trials such as the PLACE trial, as well as large retrospective, non-randomised treatment studies regarding the treatment of CSC suggest the feasibility of a more evidence-based approach when considering treatment options. The aim of this review is to provide a comprehensive overview of the current rationale and evidence with respect to the variety of interventions available for treating CSC, including pharmacology, laser treatment, and photodynamic therapy. In addition, we describe the complexity of CSC, the challenges associated with treating CSC, and currently ongoing studies. Many treatment strategies such as photodynamic therapy using verteporfin, oral mineralocorticoid antagonists, and micropulse laser treatment have been reported as being effective. Currently, however, the available evidence suggests that half-dose (or half-fluence) photodynamic therapy should be the treatment of choice in chronic CSC, whereas observation may be the preferred approach in acute CSC. Nevertheless, exceptions can be considered based upon patient-specific characteristics.

Effects of subthreshold diode micropulse laser photocoagulation on treating patients with refractory diabetic macular edema

Purpose

To evaluate the effects of subthreshold diode micropulse laser photocoagulation on treating patients with refractory diabetic macular edema (DME).

Methods

This randomized clinical trial recruited patients with DME in both eyes that were resistant to treatment with intravitreal bevacizumab (IVB). The eyes were randomly divided into two groups who received laser therapy and IVB, or IVB alone. Subthreshold diode micropulse laser photocoagulation and IVB injection were administered in one eye, and an IVB injection was administered in the second eye. IVB injections were repeated in both eyes within one month and two months after the first injection. Best corrected visual acuity (BCVA) logarithm of the minimum angle of resolution (logMAR) and central macular thickness (CMT) were measured before, within a month, and three months after start of intervention.

Results

In this study, 42 eyes of 21 patients were evaluated. The mean age of patients was 60.86 ± 8.57 years. Ten patients (47.6%) were male. Within-group analysis showed a significant decreased in BCVA logMAR in the laser + IVB group reflecting improvement in visual acuity (VA) (P < 0.001); it increased in the control group during study reflecting more vision loss (P = 0.01). In the laser + IVB group, a significant decrease in mean ± standard deviation (SD) CMT at 3 months compared to baseline was observed (baseline: 513 ± 126.29 vs. three months: 408.1 ± 95.28; P < 0.001). The mean ± SD CMT was significantly lower in the laser + IVB group of eyes than in the control group three months after intervention (P = 0.02).

Conclusion

Using subthreshold diode micropulse laser photocoagulation in combination with IVB can significantly reduce CMT and improve BCVA in patients with refractory DME.

Application of subthreshold laser therapy in retinal diseases: a review

Introduction

Laser photocoagulation has been a valuable tool in the ophthalmologist's armamentarium for decades. Conventional laser photocoagulation relies on visible retinal burns as a treatment endpoint, which is thought to result in photocoagulative necrosis of retinal tissue. Recent studies have suggested that using subthreshold (ST) laser, which does not cause detectable damage to the retina may also have therapeutic effects in a variety of retinal diseases. Areas covered: We review the proposed biological mechanisms mediating the therapeutic effects of subthreshold laser on the retina, followed by the evidence for ST laser efficacy in retinal diseases such as diabetic macular edema, central serous chorioretinopathy, age-related macular degeneration, and retinal vein occlusion.

Expert Commentary

Multiple clinical studies demonstrate that subthreshold laser does not cause structural damage to the retina based on multimodal imaging. Evidence suggests that there is a therapeutic effect on decreasing diabetic macular edema and subretinal fluid in chronic central serous retinopathy; however, the effect may be relatively modest and is not as efficacious as first line treatments for these diseases. Given the repeatability and lack of damage to the retina by this treatment, subthreshold laser deserves further study to determine its place in the retina specialist's armamentarium.

Development of low-cost photoacoustic imaging systems using very low-energy pulsed laser diodes

With the growing application of photoacoustic imaging (PAI) in medical fields, there is a need to make them more compact, portable, and affordable. Therefore, we designed very low-cost PAI systems by replacing the expensive and sophisticated laser with a very low-energy laser diode. We implemented photoacoustic (PA) microscopy, both reflection and transmission modes, as well as PA computed tomography systems. The images obtained from tissue-mimicking phantoms and biological samples determine the feasibility of using a very low-energy laser diode in these configurations.

Multi-Modal Longitudinal Evaluation of Subthreshold Laser Lesions in Human Retina, Including Scanning Laser Ophthalmoscope-Adaptive Optics Imaging

BACKGROUND AND OBJECTIVE

Subthreshold retinal laser therapy is efficacious for a variety of retinovascular disorders. Currently, it is unknown which laser parameters can ensure no detectable damage to human retina tissue.

MATERIALS AND METHODS

One informed physician participant with a normal retina was treated with three levels (75%, 50%, and 25%) of subthreshold 577-nm laser (PASCAL; Topcon, Santa Clara, CA) at 20-millisecond (ms) duration and 100 µm spot size. Several high-resolution retinal imaging modalities, including spectral-domain optical coherence tomography (SD-OCT) and scanning laser ophthalmoscope-adaptive optics (SLO-AO), were used to longitudinally image retinal laser lesions during a 9-month period.

RESULTS

SLO-AO and SD-OCT imaging of subthreshold laser therapy in human retina showed no cone cell or RPE damage at all time points during a 9-month period using the 25% threshold power 577-nm laser in the human retina.

CONCLUSION

It is likely that subthreshold laser therapy with 577-nm laser at 20-ms duration in the human retina is safe at the 25% of threshold power level.

Diabetic Retinopathy Clinical Practice Guidelines: Customized for Iranian Population

PURPOSE

To customize clinical practice guidelines (CPGs) for management of diabetic retinopathy (DR) in the Iranian population.

METHODS

Three DR CPGs (The Royal College of Ophthalmologists 2013, American Academy of Ophthalmology [Preferred Practice Pattern 2012], and Australian Diabetes Society 2008) were selected from the literature using the AGREE tool. Clinical questions were designed and summarized into four tables by the customization team. The components of the clinical questions along with pertinent recommendations extracted from the above-mentioned CPGs; details of the supporting articles and their levels of evidence; clinical recommendations considering clinical benefits, cost and side effects; and revised recommendations based on customization capability (applicability, acceptability, external validity) were recorded in 4 tables, respectively. Customized recommendations were sent to the faculty members of all universities across the country to score the recommendations from 1 to 9.

RESULTS

Agreed recommendations were accepted as the final recommendations while the non-agreed ones were approved after revision. Eventually, 29 customized recommendations under three major categories consisting of screening, diagnosis and treatment of DR were developed along with their sources and levels of evidence.

CONCLUSION

This customized CPGs for management of DR can be used to standardize the referral pathway, diagnosis and treatment of patients with diabetic retinopathy.

Comparison of subthreshold diode laser micropulse therapy versus conventional photocoagulation laser therapy as primary treatment of diabetic macular edema

PURPOSE

The aim of the present study was to investigate the effect of subthreshold diode laser micropulse (SDM) in comparison with conventional laser photocoagulation in the treatment of the diabetic macular edema (DME).

METHODS

Sixty-eight eyes from 68 patients with clinically significant DME were divided randomly into two equal groups. In the first group, SDM photocoagulation was employed, while conventional laser photocoagulation was performed on the eyes of the second group. Central macular thickness (CMT), central macular volume (CMV), and best corrected visual acuity (BCVA) were measured before, 2, and 4 months after intervention, and the results were compared.

RESULTS

The mean CMT was 357.3 and 354.8 microns before the treatment in Groups 1 and 2, respectively (P = 0.85), and decreased significantly to 344.3 and 349.8 after 4 months, respectively (P = 0.012 and P = 0.049). The changes in the central macular thickness was statistically higher in the first group (P = 0.001). The mean CMV significantly decreased in Group 1 (P = 0.003), but it was similar to pretreatment in Group 2 after 4 months (P = 0.31). The BCVA improved significantly in Group 1 (P < 0.001), but it remained unchanged in Group 2 (P = 0.38).

CONCLUSIONS

In this study, SDM was more effective than conventional laser photocoagulation in reducing CMT and CMV and improving visual acuity in patients with DME.

Side-effects and complications of laser treatment in diabetic retinal disease

Laser treatment for diabetic retinopathy was the first intraocular treatment to provide a highly effective means for preventing visual loss in patients with diabetes. Although inherently destructive, laser treatment is remarkably effective in preventing visual loss and preserving vision long-term. This review will describe briefly the current techniques and discuss in detail the reported side-effects and potential complications of laser treatment of diabetic retinal disease.

Safety of transfoveal subthreshold diode micropulse laser for fovea-involving diabetic macular edema in eyes with good visual acuity

PURPOSE

To determine the safety of transfoveal subthreshold diode micropulse laser for fovea-involving diabetic macular edema.

METHODS

The records of all patients treated with transfoveal subthreshold diode micropulse laser for fovea-involving diabetic macular edema in two retina clinics were reviewed. The eligibility included fovea-involving diabetic macular edema by spectral domain optical coherence tomography and pretreatment visual acuity of 20/40 or better.

RESULTS

Thirty-nine eyes of 27 patients aged 50 years to 87 years (mean, 69 years) were included. Postoperative follow-up ranged from 3 months to 36 months (mean, 11 months). Fourteen patients were insulin dependent, and 19 had nonproliferative retinopathy. The preoperative visual acuity was 20/20 (10 eyes), 20/25 (10 eyes), 20/30 (8 eyes), and 20/40 (11 eyes). No eye had evidence of laser-induced macular damage by any imaging means postoperatively. There were no adverse treatment effects. Logarithm of the minimum angle of resolution visual acuity was improved on average of 0.03 units at 4 months to 7 months of follow-up (P = 0.0449, paired t-test) and otherwise stable. The central foveal thickness was improved at 4 months to 7 months (P = 0.05, paired t-test) and 8 months to 12 months, postoperatively (P = 0.04, mixed model accounting). Maximum macular thickness was improved at 4 months to 7 months postoperatively (P = 0.01, paired t-test and mixed model accounting).

CONCLUSION

In a small retrospective series, transfoveal subthreshold diode micropulse laser was safe and effective for the treatment of fovea-involving diabetic macular edema in eyes with good preoperative visual acuity that were not the candidates for conventional photocoagulation or intravitreal injection. Further study is warranted.

Randomised clinical trial evaluating best-corrected visual acuity and central macular thickness after 532-nm subthreshold laser grid photocoagulation treatment in diabetic macular oedema

Purpose

To compare best-corrected visual acuity (BCVA) and central macular thickness (CMT) after 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation for the treatment of diabetic macular oedema (DME).

Patients and methods

Twenty-three patients (46 eyes) with binocular DME were enroled in this study. The two eyes of each patient were divided into a subthreshold photocoagulation group and a threshold photocoagulation group. The eyes of the subthreshold group underwent 532-nm patter scan laser system (PASCAL) 50% end point subthreshold laser grid photocoagulation therapy, whereas the threshold photocoagulation group underwent short-pulse grid photocoagulation with a 532-nm PASCAL system. BCVA and CMT were assessed in all patients before treatment, 7 days after treatment, and 1, 3, and 6 months after treatment.

Results

After grid photocoagulation, the mean BCVA improved in both the subthreshold group, and the threshold group, and the two groups did not differ statistically significantly from each other. Similarly, the macular oedema diminished in both groups after treatment, and the two groups did not differ statistically significantly from each other with regard to CMT.

Conclusion

Both 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation can improve the visual acuity and reduce CMT in DME patients.

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.

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.

Subthreshold diode-laser micropulse photocoagulation as a primary and secondary line of treatment in management of diabetic macular edema

Background

The purpose of this study was to evaluate subthreshold diode-laser micropulse (SDM) photocoagulation as a primary and secondary line of treatment for clinically significant diabetic macular edema (CSDME).

Methods

In this prospective nonrandomized case series, 220 cases of nonischemic CSDME were managed primarily and secondarily by SDM photocoagulation on a 15% duty cycle with a mean power of 828 mW and a spot size of 75–125 μm. SDM treatment was repeated at 3–4-month intervals if residual leakage was observed. Additional intravitreal pharmacologic therapy was used according to the response. Follow-up varied from 12 to 19 (mean 14±2.8) months. Novel software designed by the authors was used to record the subvisible threshold laser applications and their parameters on the fundus image of the eye. Evaluation of the results of treatment was done using fluorescein angiography and optical coherence tomography (OCT). Primary outcome measures included changes in visual acuity and foveal thickness at OCT. Secondary outcome measures included visual loss of one or more Snellen lines and laser scars detectable on fundus biomicroscopy or fluorescein angiography.

Results

In the primary treatment group, there was significant improvement or stabilization of visual acuity after the first 3–4 months, which was stable thereafter. Visual acuity was stable in the secondary treatment group. A corresponding reduction of macular thickness on OCT was noted during the follow-up period in both groups. Additional therapy included repeat SDM photocoagulation, intravitreal injection of triamcinolone, and pars plana vitrectomy. Laser marks seen as changes in retinal pigment epithelium on fundus biomicroscopy and fluorescein angiography were noted in 3.3% and 5.7% of cases. Our novel software could accurately record the location of all SDM-invisible applications.

Conclusion

Micropulse laser is an effective minimal intensity therapy that offers the clear advantage of minimizing or avoiding laser-induced visible retinal burn/scarring while reducing the foveal thickness in the management of selected cases of CSDME. Future prospective studies should include the use of SDM photocoagulation as a combined minimally invasive therapy to consolidate the prompt but temporary effects of anti-vascular endothelial growth factor or anti-inflammatory agents. Virtual localization of SDM-invisible applications using our proprietary software could be used to guide further retreatments.

Retina rejuvenation therapy for diabetic macular edema: a pilot study

PURPOSE

To prospectively investigate the safety and efficacy of a novel frequency-doubled nanosecond-pulsed laser with discontinuous beam energy distribution (2RT, Ellex) for the treatment of diabetic macular edema.

METHODS

Twenty-three consecutive patients (38 eyes) with newly diagnosed diabetic macular edema were recruited and assessed with logarithm of the minimum angle of resolution best-corrected visual acuity, central macular thickness measured with optical coherence tomography (OCT/scanning laser ophthalmoscope, OPKO/OTI), microperimetry, fundus photography, and fundus fluorescein angiography. Macular grid treatments were performed with 2RT laser system by 1 operator. Patients were examined with logarithm of the minimum angle of resolution best-corrected visual acuity, central macular thickness, microperimetry, and fundus photography at 3 weeks and 6 weeks and 3 months and 6 months. Fundus fluorescein angiography was repeated at 3 months and 6 months.

RESULTS

Six months postoperatively, 17 patients (28 eyes) completed the study. No complications were identified after 2RT therapy. Intraoperative retinal discoloration was observed in 2 cases, fully resolved at 3 months with no permanent anatomical or functional changes. Mean logarithm of the minimum angle of resolution visual acuity improved from 20/44 at baseline to 20/27 at 6 months. The change in best-corrected visual acuity was significant (P = 0.0190). Central macular thickness in the central 1-mm subfield, retinal exudates and vascular leakage decreased in the majority of patients at 6 months (46, 41, and 55%, respectively), although the change from baseline was not statistically significant. Microperimetry confirmed photoreceptor integrity and showed a trend of improvement that correlated with decreased central macular thickness.

CONCLUSION

For the first time, we achieved a beneficial effect on diabetic macular edema without the side effects of conventional laser therapy. The efficacy of this system in comparison with standard argon laser photocoagulation and in the treatment of other conditions affecting the retinal pigment epithelium needs further investigation.

Diabetic macular edema: therapeutic options

Treatment for diabetic macular edema (DME) is continuously evolving with the advent of pharmacologic therapies. Focal laser photocoagulation remains the historical standard of care; however, a new wave of studies is rapidly emerging that shows the benefit of intravitreal antivascular endothelial growth factor medications and corticosteroids. The goal of this review is to compare the various treatment options for DME, and include data from the most recent clinical trials of therapies for this complex condition.

Subthreshold diode laser micropulse photocoagulation for the treatment of diabetic macular edema

Diabetic macular edema (DME) is a sight-threatening complication of diabetic retinopathy, the leading cause of visual loss in the working-age population in the industrialized and emerging world. The standard of care for DME is focal/grid laser photocoagulation, which is proven effective in reducing the risk of vision loss, but inherently destructive and associated with tissue damage and collateral effects. Subthreshold diode laser micropulse photocoagulation is a nondestructive tissue-sparing laser procedure, which, in randomized controlled trials for the treatment of DME, has been found equally effective as conventional photocoagulation. Functional and anatomical outcomes from four independent randomized controlled trials provide level one evidence that vision stabilization/improvement and edema resolution/reduction can be elicited with less or no retinal damage, and with fewer or no complications. This review describes the principles of subthreshold diode laser micropulse photocoagulation, its treatment modalities and clinical outcomes in the context of standard laser treatments and of emerging nonlaser therapies for DME.

Subthreshold diode micropulse laser photocoagulation (SDM) as invisible retinal phototherapy for diabetic macular edema: a review

PURPOSE

To present the state-of-the-art of subthreshold diode laser micropulse photocoagulation (SDM) as invisible retinal phototherapy for diabetic macular edema (DME).

METHOD

To review the role and evolution of retinal laser treatment for DME.

RESULTS

Thermal laser retinal photocoagulation has been the cornerstone of treatment for diabetic macular edema for over four decades. Throughout, laser induced retinal damage produced by conventional photocoagulation has been universally accepted as necessary to produce a therapeutic benefit, despite the inherent risks, adverse effects and limitations of thermally destructive treatment. Recently, SDM, performed as invisible retinal phototherapy for DME, has been found to be effective in the absence of any retinal damage or adverse effect, fundamentally altering our understanding of laser treatment for retinal disease.

SUMMARY

The discovery of clinically effective and harmless SDM treatment for DME offers exciting new information that will improve our understanding of laser treatment for retinal disease, expand treatment indications, and improve patient outcomes.

Long-term safety, high-resolution imaging, and tissue temperature modeling of subvisible diode micropulse photocoagulation for retinovascular macular edema

PURPOSE

To determine the long-term safety of high-density subvisible diode micropulse photocoagulation (810 nm), compare the clinical findings with computational modeling of tissue hyperthermia and to report results for a subset of eyes treated for diabetic macular edema (ME) documented pre- and postoperatively by spectral-domain optical coherence tomography.

METHOD

All eyes treated for ME from diabetic retinopathy (diabetic ME) and branch retinal vein occlusion between April 2000 and January 2010 were reviewed for subvisible diode micropulse laser-induced retinal damage. Therapeutic outcomes were reviewed for a subgroup treated for diabetic ME with pre- and postoperative spectral-domain optical coherence tomography. Laser-induced retinal thermal effects were modeled computationally using Arrhenius formalism.

RESULTS

A total of 252 eyes (212 diabetic ME, 40 branch retinal vein occlusion) of 181 patients qualified. None of the 168 eyes treated at irradiance <350 W/cm2 and 7 of 84 eyes at ≥ 590 W/cm2 had retinal damage (P = 0.0001) (follow-up 3-120 months, median, 47). Sixty-two eyes of 48 patients treated for diabetic ME with pre- and postoperative spectral-domain optical coherence tomography with median 12 months follow-up had no retinal injury by infrared, red-free, or fundus autofluorescence photos; fluorescein angiography or indocyanine green angiography; or spectral-domain optical coherence tomography. Central foveal thickness (P = 0.04) and maximum macular thickness decreased (P < 0.0001). Modeling of retinal hyperthermia demonstrates that the sublethal clinical regimen corresponds to Arrhenius integral >0.05, while damage is likely to occur if it exceeds 1.

CONCLUSION

Subvisible diode micropulse can effectively treat retinovascular ME without laser-induced retinal damage, consistent with Arrhenius modeling of pulsed hyperthermia.

Online optical coherence tomography during subthreshold laser irradiation

PURPOSE

To investigate the role of real-time optical coherence tomography (OCT) in the detection of standard and nonvisible subthreshold laser irradiation.

METHODS

We used an integrated platform consisting of a slit-lamp, a digital camera, a slit-lamp mounted OCT, and a 532-nm laser photocoagulator (Topcon Inc., Tokyo, Japan). The laser aiming beam and the OCT scan were aligned to obtain real-time tomographic imaging of the irradiated area during laser exposure. Standard and subthreshold laser irradiation and simultaneous OCT acquisition were tested in artificial and biological samples. Laser testing cards were chosen as artificial samples. Freshly enucleated pig eyes were used for iris irradiation.

RESULTS

Ophthalmoscopically visible reference burns were placed on the laser testing card in 2 parallel lines. Then, a series of laser spots with the same size and duration but different power were placed between the reference burns. Online OCT during laser irradiation detected changes in the reflectivity profile of the artificial sample at a power of 200 mW, in absence of ophthalmoscopically visible lesions. Similarly, reference burns were placed on pig iris and between them various laser spots were performed at ranging powers. Changes in the iris optical properties, as detected with online OCT, were produced with a power of 860 mW in absence of visible endpoint.

CONCLUSIONS

Online OCT is able to identify non-ophthalmoscopically visible lesions during subthreshold laser irradiation either in artificial samples or in pig iris.

Long-term therapeutic efficacy of the subthreshold micropulse diode laser photocoagulation for diabetic macular edema

PURPOSE

To investigate the long-term efficacy of subthreshold micropulse diode laser photocoagulation (SMDLP) on diabetic macular edema (DME).

METHODS

The effects of SMDLP (810 nm) were studied on 56 eyes of 44 patients with DME. Optical coherence tomography-determined foveal thickness and best-corrected visual acuity (BCVA) were evaluated at 1, 3, 6, and 12 months after the SMDLP.

RESULTS

The mean foveal thickness was 504 μm before the SMDLP, and it was significantly reduced to 439 μm at 1 month (P = 0.001), 409 μm at 3 months (P < 0.0001), 358 μm at 6 months (P < 0.0001), and 320 μm at 12 months (P < 0.0001). The mean BCVA at baseline was 0.47 logarithm of the minimal angle of resolution (logMAR) units, and it was not changed significantly at all of the postoperative examinations. Among the 56 eyes, 10 (17.8%) had an improvement of BCVA of >0.2 logMAR units, 36 (64.2%) remained the same, and 10 eyes (17.8%) had a reduction of >0.2 logMAR units at 12 months postoperatively.

CONCLUSION

Our results indicate that SMDLP has a beneficial effect on DME. However, prospective studies are needed to evaluate this technique in more detail.

Visualization of subthreshold micropulse diode laser photocoagulation by scanning laser ophthalmoscopy in the retro mode

PURPOSE

To assess the efficacy of scanning laser ophthalmoscopy in the retro mode, employing a new dark-field aperture, for detecting laser spots created by subthreshold diode laser micropulse photocoagulation.

DESIGN

Interventional case series.

METHODS

setting: Institutional. patients: Eight consecutive patients (8 eyes) with clinically significant diabetic macular edema and 1 patient (1 eye) with macular edema attributable to branch vein occlusion underwent subthreshold diode laser micropulse photocoagulation. Scanning laser ophthalmoscopy images were obtained before and immediately after subthreshold laser photocoagulation. Application of the laser was done under 3 different sets of conditions with a 15% duty cycle for 0.2 seconds in the micropulse mode: condition I was 200-μm spots at 200% of the threshold power in the continuous wave mode, condition II was 200-μm spots at 300%, and condition III was 125-μm spots at 250% or 300%. The laser-treated area was monitored on both color images and by scanning laser ophthalmoscopy (F-10, NIDEK, Gamagori, Japan).

RESULTS

Immediately after subthreshold laser photocoagulation, there were no obvious laser scars affecting the treated area in any of the patients on color images. Scanning laser ophthalmoscopy with a diode laser in the retro mode showed no obvious changes after treatment under condition I. However, conditions II and III resulted in dark spots at the sites where the laser had been applied in 5 out of 7 patients.

CONCLUSIONS

Scanning laser ophthalmoscopy in the retro mode is useful to detect sites of subthreshold micropulse laser application. The dark spots detected by retro mode scanning laser ophthalmoscopy are probably related to swelling of the pigment epithelium after laser application. This method is useful to confirm the invisible spots created by subthreshold diode laser micropulse photocoagulation.

Micropulsed diode laser therapy: evolution and clinical applications

Many clinical trials have demonstrated the clinical efficacy of laser photocoagulation in the treatment of retinal vascular diseases, including diabetic retinopathy. There is, however, collateral iatrogenic retinal damage and functional loss after conventional laser treatment. Such side effects may occur even when the treatment is appropriately performed because of morphological damage caused by the visible endpoint, typically a whitening burn. The development of the diode laser with micropulsed emission has allowed subthreshold therapy without a visible burn endpoint. This greatly reduces the risk of structural and functional retinal damage, while retaining the therapeutic efficacy of conventional laser treatment. Studies using subthreshold micropulse laser protocols have reported successful outcomes for diabetic macular edema, central serous chorioretinopathy, macular edema secondary to retinal vein occlusion, and primary open angle glaucoma. The report includes the rationale and basic principles underlying micropulse diode laser therapy, together with a review of its current clinical applications.

Micropulse transscleral diode laser cyclophotocoagulation in the treatment of refractory glaucoma

BACKGROUND

Transscleral diode laser cyclophotocoagulation (TSCPC) is an established method of treatment for refractory glaucoma, but is associated with significant complications. This study evaluates the efficacy and safety of a new form of TSCPC using micropulse diode laser and trans-pars plana treatment with a novel contact probe.

METHODS

Prospective interventional case series of 40 eyes of 38 consecutive patients with refractory glaucoma treated with micropulse TSCPC with a novel probe. Outcomes measured were success, hypotony and response rates.

RESULTS

The mean age of patients was 63.2 +/- 16.0 years. The mean follow-up period was 16.3 +/- 4.5 months. The mean intraocular pressure (IOP) before micropulse TSCPC was 39.3 +/- 12.6 mmHg. Mean IOP decreased to 31.1 +/- 13.4 mmHg at 1 day, 28.0 +/- 12.0 mmHg at 1 week, 27.4 +/- 12.7 mmHg at 1 month, 27.1 +/- 13.6 mmHg at 3 months, 25.8 +/- 14.5 mmHg at 6 months, 26.6 +/- 14.7 mmHg at 12 months and 26.2 +/- 14.3 mmHg at 18 months (P < 0.001 at all time points). No patient had hypotony or loss of best-corrected visual acuity. The overall success rate after a mean of 1.3 treatment sessions was 72.7%.

CONCLUSION

Micropulse TSCPC is a safe and effective method of lowering IOP in cases of refractory glaucoma and is comparable with conventional TSCPC.

Barely visible 10-millisecond pascal laser photocoagulation for diabetic macular edema: observations of clinical effect and burn localization

PURPOSE

To investigate the morphologic features and clinical efficacy of barely visible Pascal (Optimedica Corporation) photocoagulation burns in diabetic macular edema (DME) using Fourier-domain optical coherence tomography (FD OCT) and fundus autofluorescence (AF).

DESIGN

Interventional case series.

METHODS

Retrospective evaluation of 10 eyes with newly diagnosed DME that underwent barely visible Pascal photocoagulation using an array of 10-microm, 10-millisecond photocoagulation burns. FD OCT and camera-based AF was performed at baseline and at 1 hour, 2 weeks, 4 weeks, and 12 weeks after laser. Changes in retinal thickening after laser treatment were measured using retinal thickness maps within the treated sector and the central foveal subfield.

RESULTS

At 1 hour after treatment, burns were visualized partially with clinical biomicroscopy. AF demonstrated spots lacking autofluorescence that confirmed effective laser uptake within the Pascal arrays. Sequential changes in hyperreflectivity on FD OCT correlated with morphologic alterations seen on AF. Burns became increasingly hyperautofluorescent between 2 and 4 weeks. There were significant reductions in the retinal thickness within treated sectors on FD OCT at 2 weeks (26 +/- 32 microm; P = .012) and 3 months after laser (20 +/- 21 microm; P = .02) compared with baseline. Clinical biomicroscopic reduction of DME was the most common finding in 80%.

CONCLUSIONS

Barely visible 10-millisecond Pascal laser seems to produce an effect at the level of the inner and outer photoreceptor segments and apical retinal pigment epithelium, with minimal axial and lateral spread of burns. FD OCT confirmed spatial localization of AF signal changes that correlated with laser burn-tissue interactions over 3 months. The technique of lower-fluence barely visible 10-millisecond laser may reduce retinal edema within affected sectors and effectively treat DME with minimization of scar formation.