One-Year Functional and Anatomical Outcomes After Selective Retina Therapy With Real-Time Feedback-Controlled Dosimetry in Patients With Intermediate Age-Related Macular Degeneration: A Pilot Study

Real-time OCT feedback-controlled RPE photodisruption in ex vivo porcine eyes using 8 microsecond laser pulses

Selective retinal pigment epithelium (RPE) photodisruption requires reliable real-time feedback dosimetry (RFD) to prevent unwanted overexposure. In this study, optical coherence tomography (OCT) based RFD was investigated in ex vivo porcine eyes exposed to laser pulses of 8 µs duration (wavelength: 532 nm, exposure area: 90 × 90 µm2, radiant exposure: 247 to 1975 mJ/µm2). For RFD, fringe washouts in time-resolved OCT M-scans (central wavelength: 870 nm, scan rate: 85 kHz) were compared to an RPE cell viability assay. Statistical analysis revealed a moderate correlation between RPE lesion size and applied treatment energy, suggesting RFD adaptation to inter- and intraindividual RPE pigmentation and ocular transmission.

Long-Term Multimodal Imaging Analysis of Selective Retina Therapy Laser Lesions

This study evaluates the long-term effects of selective retina therapy (SRT) on the retinal pigment epithelium (RPE) and neuroretina in patients with central serous chorioretinopathy. SRT was performed on 36 patients using a Nd:YLF-Laser at 527 nm (R:GEN®, Lutronic, Goyang-Si, Republic of Korea). A total of 994 titration spots were examined using up to three years’ multimodal imaging. Leakage in fluorescein angiography (FA) was observed after SRT in 523 lesions and resolved after one month. SRT lesions were not visible clinically, but appeared as brightly reflective areas in infrared and multicolor images. Normal morphology was observed in optical coherence tomography (OCT) immediately after SRT. After one month, thickening of the RPE and interdigitation zone changes were seen and disappeared after 539 ± 308 days. No RPE atrophies occurred during the observation period. Decreased fundus autofluorescence (FAF) was mostly observed directly after SRT followed by increased FAF at one month, which faded over time. A significant decrease in the number of visible lesions in the FA and FAF was observed within the three-year follow-up. OCT findings are consistent with animal studies showing SRT-related defect closure by hypertrophy and migration of neighboring cells without RPE atrophy or photoreceptor damage. This suggests that SRT is a safe treatment option for macular diseases and does not lead to retinal atrophy.

Factors Predicting Response to Selective Retina Therapy in Patients with Chronic Central Serous Chorioretinopathy

This retrospective study aimed to assess the safety and efficacy of selective retina therapy (SRT) with real-time feedback-controlled dosimetry (RFD) for chronic central serous chorioretinopathy (CSC) and to evaluate factors predictive of treatment response. We included 137 eyes of 135 patients with chronic CSC. SRT was performed to cover each of the leakage areas on fundus fluorescein angiography. Changes in mean best-corrected visual acuity (BCVA), central macular thickness (CMT), and subretinal fluid (SRF) height were evaluated at baseline and at 3 and 6 months after treatment. Complete SRF resolution was observed in 52.6% (72/137 eyes) and 90.5% (124/137 eyes) at 3 and 6 months, respectively. Mean BCVA (logMAR) significantly improved from 0.41 ± 0.31 at baseline to 0.33 ± 0.31 at month 6 (p < 0.001). Mean CMT significantly decreased from 347.67 ± 97.38 μm at baseline to 173.42 ± 30.95 μm at month 6 (p < 0.001). Mean SRF height significantly decreased from 187.85 ± 97.56 µm at baseline to 8.60 ± 31.29 µm after 6 months (p < 0.001). Baseline SRF height was a significant predictive factor for retreatment requirement (p = 0.008). In conclusion, SRT showed favorable anatomical outcomes in patients with chronic CSC. A higher baseline SRF height was a risk factor for retreatment.

Selective retina therapy and thermal stimulation of the retina: different regenerative properties - implications for AMD therapy

BACKGROUND

Selective Retina Therapy (SRT), a photodisruptive micropulsed laser modality that selectively destroys RPE cells followed by regeneration, and Thermal Stimulation of the Retina (TSR), a stimulative photothermal continuous wave laser modality that leads to an instant sublethal temperature increase in RPE cells, have shown therapeutic effects on Age-related Macular Degeneration (AMD) in mice. We investigate the differences between both laser modalities concerning RPE regeneration.

METHODS

For PCR array, 6 eyes of murine AMD models, apolipoprotein E and nuclear factor erythroid-derived 2- like 2 knock out mice respectively, were treated by neuroretina-sparing TSR or SRT. Untreated litter mates were controls. Eyes were enucleated either 1 or 7 days after laser treatment. For morphological analysis, porcine RPE/choroid organ cultures underwent the same laser treatment and were examined by calcein vitality staining 1 h and 1, 3 or 5 days after irradiation.

RESULTS

TSR did not induce the expression of cell-mediators connected to cell death. SRT induced necrosis associated cytokines as well as inflammation 1 but not 7 days after treatment. Morphologically, 1 h after TSR, there was no cell damage. One and 3 days after TSR, dense chromatin and cell destruction of single cells was seen. Five days after TSR, there were signs of migration and proliferation. In contrast, 1 h after SRT a defined necrotic area within the laser spot was seen. This lesion was closed over days by migration and proliferation of adjacent cells.

CONCLUSIONS

SRT induces RPE cell death, followed by regeneration within a few days. It is accompanied by necrosis induced inflammation, RPE proliferation and migration. TSR does not induce immediate RPE cell death; however, migration and mitosis can be seen a few days after laser irradiation, not accompanied by necrosis-associated inflammation. Both might be a therapeutic option for the treatment of AMD.

The Effect of Selective Retina Therapy for Bevacizumab-Resistant Chronic Central Serous Chorioretinopathy

PURPOSE

The aim of this study was to evaluate the efficacy of selective retina therapy (SRT), used in conjunction with real-time feedback dosimetry (RFD), in the treatment of bevacizumab-resistant chronic central serous chorioretinopathy (CSC).

PATIENTS AND METHODS

In this retrospective cohort study, 22 eyes of 22 patients with bevacizumab-resistant chronic CSC, showing focal or diffuse foveal leakages on fundus fluorescein angiography (FFA), were included. After evaluation of the test spots at temporal arcades, SRT (wavelength, 527 nm; pulse repetition rate, 100 Hz; ramping over maximal 15 micropulses; and spot diameter, 200 μm) using RFD was applied to the leakage sites observed on FFA. Changes in the mean best-corrected visual acuity (BCVA), central macular thickness (CMT), and subretinal fluid (SRF) height were evaluated at baseline and at 1, 3, 6, 9, and 12 months following treatment.

RESULTS

SRF completely resolved in 81.8% (18/22 eyes) cases at 12 months post-treatment. The mean BCVA (logarithm of the minimum angle of resolution [logMAR]) improved from 0.49 ± 0.29 at baseline to 0.43 ± 0.36 at 12 months (p = 0.067). The mean BCVA gain was 0.06 logMAR, equivalent to 3 ETDRS letters. The CMT significantly decreased from 323 ± 85.6 μm at baseline to 221.5 ± 60.4 μm at 12 months (p < 0.001). The mean SRF height also significantly decreased from 174.6 ± 86.4 μm at baseline to 35.1 ± 75.4 μm at 12 months (p < 0.001).

CONCLUSION

SRT showed favorable visual and anatomical outcomes in patients with bevacizumab-resistant chronic CSC.

The Effect of Selective Retina Therapy with Automatic Real-Time Feedback-Controlled Dosimetry for Chronic Central Serous Chorioretinopathy: A Randomized, Open-Label, Controlled Clinical Trial

This prospective randomized controlled trial evaluated the safety and efficacy of real-time feedback-controlled dosimetry (RFD)-guided selective retina therapy (SRT) in chronic central serous chorioretinopathy (CSC). Forty-four participants with chronic CSC were included and randomly assigned to the control group or SRT group. The SRT laser system with RFD-guidance was applied to cover the entire leakage area. If SRF remained at the 6-week follow-up visit, re-treatment and rescue SRT was performed for the SRT group and crossover group, respectively. The rate of complete resolution of subretinal fluid (SRF), mean SRF height, and mean retinal sensitivity were compared between the two groups at 6-weeks post-treatment. The complete SRF resolution rate in all SRT-treated eyes was evaluated at 12-weeks post-treatment. The rate of complete SRF resolution was significantly higher in the SRT group (63.6%) than in the control group (23.8%) at 6-weeks post-treatment (p = 0.020). The mean SRF height at 6 weeks after SRT was significantly lower in the SRT group (p = 0.041). Overall, SRT-treated eyes showed complete SRF resolution in 70.3% of eyes at 12-weeks post-treatment. RFD-guided SRT was safe and effective to remove SRF in chronic CSC patients during the 3-month follow-up period.