Retinal laser - Protocols and practical tips

Background

Many a young doctors in training find retinal laser photocoagulation a daunting task. However, if correct protocols are followed and checklists are observed, then it is not difficult to have a successful laser sitting with a happy patient. Most of the complications can be avoided with correct settings and techniques.

Purpose

To enumerate the basic protocols of retinal laser photocoagulation and provide practical tips including laser settings and checklists for hassle-free laser experience.

Synopsis

Laser settings for a pan-retinal photocoagulation (PRP) for proliferative diabetic retinopathy differ from those for a focal laser for macular edema. A fill in PRP is indicated when an active Proliferative diabetic retinopathy (PDR) is seen after the initial PRP is completed. The settings and protocols for laser photocoagulation for lattice degeneration are different, and various techniques of barrage laser are discussed. Practical tips and checklists are given, which will not be found in any textbooks.

Highlights

Animated illustrations and fundus photos are used to explain the correct techniques of performing laser photocoagulation in different indications and scenarios. Detailed instructions and checklists are provided, which can be very useful to avoid complications and medicolegal problems. The practical tips and guidelines in an easy-to-understand manner make this video highly educational for the novice retinal surgeons who want to perfect their technique of retinal laser photocoagulation.

Video Link

https://youtu.be/saQ4s49ciXI.

Choroidal neovascularization removal with photo-mediated ultrasound therapy

BACKGROUND

Age-Related macular degeneration (AMD) is a major cause of irreversible central vision loss. The main reason for lost vision due to AMD is choroidal neovascularization (CNV). In the clinic, current treatments for CNV include photodynamic therapy, laser photocoagulation, and anti-vascular endothelial growth factor (VEGF) therapy.

PURPOSE

This study evaluates a novel treatment technique combining synchronized nanosecond laser pulses and ultrasound bursts, namely photo-mediated ultrasound therapy (PUT) as a potential treatment method for CNV, for its efficacy and safety in treatment of CNV via the experiments in a clinically-relevant rabbit model in vivo.

METHODS

CNV was created by subretinal injection of Matrigel and vascular endothelial growth factor (M&V) in 10 New Zealand white rabbits. Six rabbits were used in the PUT group. In the control groups, two rabbits were treated by laser-only, and two rabbits were treated by ultrasound-only. The treatment efficacy was evaluated through fundus photography and fluorescein angiography (FA) longitudinally for up to 4 weeks. Rabbits were sacrificed for histopathology at 3 months after treatment to examine the safety of PUT.

RESULTS

The fluorescein leakage on FA was quantified to longitudinally evaluate treatment outcome. Compared with baseline, the relative intensity index was reduced by 26.57% ± 8.66% at 3 days after treatment, 27.24% ± 6.21% at 1 week after treatment, 27.79% ± 2.61% at 2 weeks after treatment, and 32.12% ± 3.23% at 4 weeks after treatment, all with a statistically significant difference of P < 0.01. The comparison between the relative intensity indexes from the two control groups (laser-only treatment and ultrasound-only treatment) did not show any statistically significant difference at all time points. Safety evaluation at 3 months with histopathology demonstrated that the PUT did not result in morphologic changes to the neurosensory retina.

CONCLUSIONS

This study introduces PUT for the first time for the treatment of CNV. The results demonstrated good efficacy and safety of PUT to treat CNV in a clinically-relevant rabbit model. With a single session of treatment, PUT can safely reduce the leakage of CNV for at least 1 month after treatment. This article is protected by copyright. All rights reserved.

Long-Term Visual Function Effects of Pan-Retinal Photocoagulation in Diabetic Retinopathy and Its Impact in Real Life

PURPOSE

To address the long-term visual function after bilateral pan-retinal photocoagulation (PRP) and its impact in real life, namely on visual field (VF) legal criteria to drive. To determine potential predictors related to clinical factors and treatment strategies.

PATIENTS AND METHODS

Observational cross-sectional study. Eyes from diabetic patients diagnosed with diabetic retinopathy who underwent bilateral PRP, with or without macular treatments and with visual acuity legal criteria for non-professional driving were randomly assigned. Main outcomes were: demographic and clinical data including best corrected visual acuity; binocular visual field (EBST-Esterman Binocular Suprathreshold Test, Humphrey analyzer3^®); contrast sensitivity (CS-Metrovision-MonPack3^®); light scattering in the retina (HD Analyzer, Visiometrics^®).

RESULTS

Seventy-one diabetic patients included (44 men and 27 women), with a mean age of 62.2±11.8 years. PRP was performed, on average, 9.7±6.9 years before the study. The average EBST Score was 85.8±17.0 and the average CS (2-5cpd) was 19.5±2.9 dB in photopic and 14.2±4.1 dB in mesopic conditions. Through a multivariate regression model, after adjusting to the clinical and demographic factors as possible confounders, we found that treatment factors associated with worse results were the use of Argon laser for the EBST Score, the very confluent PRP for the number of non-viewed points in the central 30°x20° of the EBST and the presence of macular treatments for the CS tests. According to Portuguese law, 79% (n=56) of patients had minimal EBST amplitudes for non-professional driving.

CONCLUSION

The functional results achieved in our sample are compatible with an active life, allowing most of the patients included to overcome the requirements of Portuguese legislation for driving light vehicles, namely at the level of the binocular visual field. These results highlight the role of PRP in the treatment of diabetic retinopathy in an era with evolving less aggressive laser options.