Philipp Prahs

Structural Changes of the Retina after Conventional Laser Photocoagulation and Selective Retina Treatment (SRT) in Spectral Domain OCT

Background: Spectral domain optical coherence tomography (SD-OCT) in patients can deliver retinal cross-sectional images with high resolution. This may allow the evaluation of the extent of damage to the retinal pigment epithelium (RPE) and the neurosensory retina after laser treatment. This article aims to investigate the value of SD-OCT in comparing laser lesions produced by conventional laser photocoagulation and selective retina treatment (SRT). Material and Methods: In a retrospective study, conventional retinal laser (CRL) lesions and SRT laser lesions were evaluated with SD-OCT. One hundred seventy-five CRL lesions were investigated in 10 patients with diabetic maculopathy at timepoints between 1 hr and 4 years after treatment. Ninety-one SRT lesions were examined in 9 patients with central serous retinopathy, geographic atrophy, and diabetic maculopathy at timepoints between 1 hr and 2 years. CRL lesions were applied with an ophthalmoscopically slightly grayish-white appearance (Nd:YAG laser at 532-nm wavelength; power 100–200 mW; retinal spot diameter 100 μm; pulse duration 100 ms). SRT lesions were applied with a Nd:YLF (527 nm; pulse duration 200 ns [30 pulses at 100 Hz]; energy 100–200 μJ/pulse; retinal spot diameter 200 μm) and were visible only angiographically. Results: All CRL lesions were characterized by high reflectivity in OCT images throughout the full thickness of the neurosensory tissue 1 hr after irradiation, suggesting complete neurosensory coagulation. Strong contraction through the full thickness of the neurosensory layers was observed within 7 days after treatment. In contrast, the neural retina appeared unaffected after SRT. For both lesion types, the RPE layer appeared to be regular or thinner immediately after treatment, whereas within a period of 4 weeks, a RPE thickening indicating RPE proliferation was observable. One year and later after treatment, CRL lesions were characterized by RPE atrophy combined with significant damage of the neurosensory tissue. SRT lesions aged one year and older revealed unaffected neurosensory structures and an intact RPE layer. Conclusion: Spectral domain OCT can be used clinically to follow the development of laser-induced lesions over time. Postoperative RPE proliferation was observed in both CRL and SRT laser lesions. RPE atrophy appeared subsequently only in CRL lesions, whereas the neurosensory retina appeared unaffected following SRT. These results suggest the selective effect of SRT in humans without causing adverse effects to the neurosensory retina.

Comparison of threshold irradiances and online dosimetry for selective retina treatment (SRT) in patients treated with 200 nanoseconds and 1.7 microseconds laser pulses

Selective retina therapy (SRT) solely affecting the RPE while sparing of the photoreceptors is usually performed with a train of repetitive laser pulses of 1.7 microseconds in duration. It was our purpose to evaluate the principle feasibility of SRT with shorter 200 nanoseconds laser pulses in patients.

Selective Retina Therapy in Acute and Chronic-Recurrent Central Serous Chorioretinopathy.

Purpose: Selective retina therapy (SRT), the confined laser heating and destruction of retinal pigment epithelial cells, has been shown to treat acute types of central serous chorioretinopathy (CSC) successfully without damaging the photoreceptors and thus avoiding laser-induced scotoma. However, a benefit of laser treatment for chronic forms of CSC is questionable. In this study, the efficacy of SRT by means of the previously used 1.7-µs and shorter 300-ns pulse duration was evaluated for both types of CSC, also considering re-treatment for nonresponders. Material and Methods: In a two-center trial, 26 patients were treated with SRT for acute (n = 10) and chronic-recurrent CSC (n = 16). All patients presented with subretinal fluid (SRF) in OCT and leakage in fluorescein angiography (FA). SRT was performed using a prototype SRT laser system (frequency-doubled Q-switched Nd:YLF-laser, wavelength 527 nm) with adjustable pulse duration. The following irradiation settings were used: a train of 30 laser pulses with a repetition rate of 100 Hz and pulse durations of 300 ns and 1.7 µs, pulse energy 120-200 µJ, retinal spot size 200 µm. Because SRT lesions are invisible, FA was always performed 1 h after treatment to demonstrate laser outcome (5-8 single spots in the area of leakage). In cases where energy was too low, as indicated by missing FA leakage, energy was adjusted and the patient re-treated immediately. Observation intervals were after 4 weeks and 3 months. In case of nonimprovement of the disease after 3 months, re-treatment was considered. Results: Of 10 patients with active CSC that presents focal leakage in FA, 5 had completely resolved fluid after 4 weeks and all 10 after 3 months. Mean visual acuity increased from 76.6 ETDRS letters to 85.0 ETDRS letters 3 months after SRT. Chronic-recurrent CSC was characterized by less severe SRF at baseline in OCT and weaker leakage in FA than in acute types. Visual acuity changed from baseline 71.6 to 72.8 ETDRS letters after 3 months. At this time, SRF was absent in 3 out of 16 patients (19%), FA leakage had come to a complete stop in 6 out of 16 patients (38%). In 6 of the remaining chronic CSC patients, repeated SRT with higher pulse energy was considered because of persistent leakage activity. After the re-treatment, SRF resolved completely in 5 patients (83.3%) after only 25 days. Conclusion: SRT showed promising results in treating acute CSC, but was less effective in chronic cases. Interestingly, re-treatment resulted in enhanced fluid resolution and dry conditions after a considerably shorter time in most patients. Therefore, SRT including re-treatment if necessary might be a valuable CSC treatment alternative even in chronic-recurrent cases.

Challenges and Complication Management in Novel Artificial Iris Implantation

Purpose Evaluation of postoperative artificial iris prosthesis-related complications. Design Retrospective cohort study. Methods Fifty-one consecutive patients underwent pupillary reconstruction using an artificial iris implant made from silicone between 2011 and 2015. Quantity and quality of complications were subclassified into three groups including mild, moderate, and severe complications. Their management and the learning curve were evaluated. Results In total, 13 (25.5%) of 51 included artificial iris implantations showed unexpected events in various degrees: mild complications: recurrent bleeding (n=1, 2.0%), slight but stable iris deviation (n=1, 2.0%), capsular fibrosis (n=2, 3.9%); moderate complications: suture cutting through the residual iris (n=1, 2.0%), glaucoma (n=3, 5.9%), and corneal decompensation (n=3, 5.9%); severe complications: artificial iris suture loosening (n=2, 3.9%) and dislocation (n=3, 5.9%), synechiae (n=2, 3.9%), glaucoma (n=2, 3.9%), and corneal decompensation (n=5, 9.8%) with the need for surgery, cystoid macular edema (n=3, 5.9%) and retinal detachment (n=1, 2.0%). The complication rate decreased from 83.3% (5 of 6 implantations) in the first year to 13.3% (2 of 15 implantations) in the 4th year. Nineteen of 45 evaluated patients showed a significant gain in best-corrected visual acuity (BCVA) from 1.09 ± 0.56 logMAR to 0.54 ± 0.48 logMAR (p < 0.001), and 13 of 45 eyes had a significant BCVA loss from 0.48 ± 0.39 logMAR to 0.93 ± 0.41 logMAR after surgery (p < 0.001). Conclusions The artificial iris is a feasible option in the treatment of iris defects with a wide spectrum of postoperative complications. The significant reduction of complications after twelve implantations implicates that the procedure is not to be recommended in low volume settings.