Laser photocoagulation as treatment of non-exudative age-related macular degeneration: state-of-the-art and future perspectives

Autonomous screening for laser photocoagulation in fundus images using deep learning

BACKGROUND

Diabetic retinopathy (DR) is a leading cause of blindness in adults worldwide. Artificial intelligence (AI) with autonomous deep learning algorithms has been increasingly used in retinal image analysis, particularly for the screening of referrable DR. An established treatment for proliferative DR is panretinal or focal laser photocoagulation. Training autonomous models to discern laser patterns can be important in disease management and follow-up.

METHODS

A deep learning model was trained for laser treatment detection using the EyePACs dataset. Data was randomly assigned, by participant, into development (n=18 945) and validation (n=2105) sets. Analysis was conducted at the single image, eye, and patient levels. The model was then used to filter input for three independent AI models for retinal indications; changes in model efficacy were measured using area under the receiver operating characteristic curve (AUC) and mean absolute error (MAE).

RESULTS

On the task of laser photocoagulation detection: AUCs of 0.981, 0.95, and 0.979 were achieved at the patient, image, and eye levels, respectively. When analysing independent models, efficacy was shown to improve across the board after filtering. Diabetic macular oedema detection on images with artefacts was AUC 0.932 vs AUC 0.955 on those without. Participant sex detection on images with artefacts was AUC 0.872 vs AUC 0.922 on those without. Participant age detection on images with artefacts was MAE 5.33 vs MAE 3.81 on those without.

CONCLUSION

The proposed model for laser treatment detection achieved high performance on all analysis metrics and has been demonstrated to positively affect the efficacy of different AI models, suggesting that laser detection can generally improve AI-powered applications for fundus images.

Age-Related Macular Degeneration - Therapies and Their Delivery

Age-related macular degeneration (ARMD) is a degenerative ocular disease that is the most important cause of irreversible vision loss in old-aged people in developed countries. Around fifty percent of vision impairments in developed countries are due to ARMD. It is a multifaceted disease that is associated with both genetic and environmental risk factors. The most important treatments option for ARMD includes laser photocoagulation, photodynamic therapy (PDT), Anti-VEGF Injections, and combination therapies. In this review, we also propose that topical ocular drug delivery with nanocarriers has more attention for the treatment of ARMD. The nanocarriers were specially designed for enhanced corneal residential time, prolonged drug release and action, and minimizing the frequency of administrations. Different types of nanocarriers were developed for the topical ocular delivery system, such as nanomicelles, nanoemulsions, nanosuspensions, liposomes, and polymeric nanoparticles. These topical ocular nanocarriers were administered topically, and they can fix the hydrophobic substances, increase solubility and improve the bioavailability of an administered drug. Hence the topical ocular delivery systems with nanocarriers provide a safe and effective therapeutic strategy and promising tool for the treatment of posterior segment ocular diseases ARMD.

Laser and anti-vascular endothelial growth factor treatment for drusenoid pigment epithelial detachment in age-related macular degeneration: 24-month outcomes

PURPOSE

After the 12-month interim safety analysis, we investigated the 24-month primary endpoint outcomes of drusenoid pigment epithelial detachment (dPED) after laser and intravitreal anti-VEGF treatment.

METHODS

Twenty-one patients with treatment-naïve bilateral intermediate AMD with dPED and visual acuity ≤ 83 letters (Snellen 20/23) were enrolled. The subject eye received low-energy PASCAL® laser (532 nm) treatment, and the fellow eye was used as the control. Intravitreal injections were administered at 3-month intervals from baseline to 12 months. Treatment outcomes, safety and development of advanced AMD lesions were analyzed.

RESULTS

The mean drusen area and dPED height were significantly reduced (17.3 ± 2.7% vs. 112.8 ± 3.1%, P < 0.001 and 11.8 ± 4.7% vs. 119.1 ± 4.6%, P < 0.001, respectively) and the mean BCVA improved (5.11 ± 1.35 vs. 0.83 ± 1.03 letters, P = 0.014) in the study eyes compared to those in the control eyes. Development of parafoveal iRORA (nGA) (67%, 12 of 18 eyes) and cRORA (GA) (22%, 4 of 18 eyes) was observed in the study eyes, whereas three cases of iRORA and cRORA in the control eyes (17%, 3 of 18 eyes; P = 0.010 and P = 0.791, respectively).

CONCLUSIONS

Laser and anti-VEGF treatment may be a potential treatment option for intermediate AMD with dPED. However, considering the relatively high rate of secondary iRORA and cRORA development, long-term follow-up is mandatory to clarify the safety and efficacy of this treatment.

Lutein and Zeaxanthin and Their Roles in Age-Related Macular Degeneration-Neurodegenerative Disease

Lutein and zeaxanthin belong to the xanthophyll family of carotenoids, which are pigments produced by plants. Structurally, they are very similar, differing only slightly in the arrangement of atoms. Key sources of these carotenoids include kale, savoy cabbage, spinach, broccoli, peas, parsley, corn, and egg yolks. The recommended daily intake of lutein is approximately 10.0 mg and that of zeaxanthin is 2 mg. Lutein intake in adults varies, with average intakes being 1-2 mg/day. Due to the lack of synthesis of consumption of these compounds in humans, these substances are extremely important for the proper functioning of certain organs of the body (eye, skin, heart, intestines). Eating a lot of dark leafy vegetables and some fruits can help to prevent our bodies from developing diseases. The protective effects of carotenoids are mainly related to their defense against oxidative stress and their ability to scavenge free radicals. Lutein and zeaxanthin are the only dietary carotenoids that accumulate in the retina, specifically the macula, and are called macular pigments. These carotenoids are concentrated by the action of specific binding proteins such as StARD3, which binds lutein, and GSTP1, which binds zeaxanthin and its dietary metabolite, mesozeaxanthin. It has been shown that supportive therapy with lutein and zeaxanthin can have a beneficial effect in delaying the progression of eye diseases such as age-related macular degeneration (AMD) and cataracts. This article presents the current state of knowledge on the role of lutein and zeaxanthin, especially from human studies targeting their metabolism and bioavailability, with recommendations to consume xanthophyll-rich foods.

Subretinal drusenoid deposits: An update

A wide spectrum of phenotypic manifestations characterizes age-related macular degeneration (AMD). Drusen is considered the hallmark of AMD and is located underneath the retinal pigment epithelium (RPE). In contrast, subretinal drusenoid deposits (SDDs), also known as reticular pseudodrusens, are located in the subretinal space, on top of the RPE. SDDs are poorly detected by clinical examination and color fundus photography. Multimodal imaging is required for their proper diagnosis. SDDs are topographically and functionally related to rods. SDDs cause a deep impairment in retinal sensitivity and dark adaptation. SDDs are dynamic structures that may grow, fuse with each other, or regress over time. An intermediate step in some eyes is the development of an acquired vitelliform lesion. The presence of SDD confers an eye a high risk for the development of late AMD. SDD leads to macular neovascularization, particularly type 3, geographic atrophy, and outer retinal atrophy.

Clinical Wide-Field Retinal Image Deep Learning Classification of Exudative and Non-Exudative Age-Related Macular Degeneration

Background: Age-related macular degeneration (AMD) is a disease that currently affects approximately 196 million individuals and is projected to affect 288 million in 2040. As a result, better and earlier detection methods for this disease are needed in an effort to provide a higher quality of care. One way to achieve this is through the utilization of machine learning. A deep neural network, specifically a convoluted neural network (CNN) can be trained to differentiate between different types of AMD images given the proper training data.

Methods: In this study, a CNN was trained on 420 Optos wide-field retinal images for 70 epochs in order to classify between exudative and non-exudative AMD. These images were obtained and labeled by ophthalmologists from the Martel Eye Clinic in Rancho Cordova, CA. 

Results: After completing the study, a model was created with 88% accuracy. Both the training and validation loss started above 1 and ended below 0.2. Despite only analyzing a single image at a time, the model was still able to accurately identify if the individual had AMD in both eyes or one eye only. The model had the most trouble with bilateral non-exudative AMD. Overall the model was fairly accurate in the other categories. It was noted that the neural network was able to further differentiate from a single image if the disease is present in left, right, or both eyes. This is a point of contention for further investigation as it is impossible for the artificial intelligence (AI) to extrapolate the condition of both eyes from only one image.

Conclusion: This research fostered the development of a CNN that was able to differentiate between exudative and non-exudative AMD. As well as determine if the disease is present in the right, left, or both eyes with a relatively high degree of accuracy. The model was trained on clinical data and can theoretically be used to classify other clinical images it has never encountered before. 

Large-Area Photoreceptor Degeneration Model in Rabbits by Photocoagulation and Oxidative Stress in the Retina

Photocoagulation is used for the treatment of retinal ischemic disease. However, due to the invasive nature of photocoagulation and variety of melanin concentrations between individuals, it is challenging to avoid damaging the adjacent photoreceptors and inducing several side effects. Previous studies indicate the role of laser power, duration, and spot size on retinal lesions, but the effect of interspot distance of the laser pulses needs to be considered in panretinal photocoagulation. In this study, we examine different parameters of photocoagulation on lesions of the retina in rabbit, finding that the lesion level of the outer nuclear layer of the retina depended on the pulse duration and laser spot size, and decreasing interspot distance could completely abolish the photoreceptor layer. The degeneration of the photoreceptor by photocoagulation occurred in 24 h and was not restored afterward. We then conducted panretinal photocoagulation in rabbit and found that oxidative stress was decreased in the inner nuclear layer of the retina, and pupillary light reflex and ERG signals were impaired. Our study could provide a rabbit model to explore the mechanism of photoreceptor degeneration and therapies for the side effects after photocoagulation.

Therapeutic Options Under Development for Nonneovascular Age-Related Macular Degeneration and Geographic Atrophy

Age-related macular degeneration (AMD) is a chronic, multifactorial disease and a leading cause of irreversible blindness in the elderly population in the Western Hemisphere. Among the two major subtypes of AMD, the prevalence of the nonneovascular (dry) type is approximately 85-90% and the neovascular (wet) type is 10-15%. Healthy lifestyle and nutritional supplements of anti-oxidative micronutrients have been shown to delay the progression of dry AMD and lower the risk of development of wet AMD, and anti-vascular endothelial growth factor (anti-VEGF) injections have been shown to improve visual acuity for wet AMD patients. However, to date, there is no approved treatment for geographic atrophy (GA), a debilitating late stage of dry AMD. Thus, this represents a large unmet need in this patient population. This review focuses on the current management and treatment of nonneovascular AMD, the drugs and devices that have been under investigation for the treatment of GA, and the latest clinical trial results. A few therapeutic options have shown initial promising clinical trial results, but failed to show efficacy in larger trials, while others are awaiting future clinical trial results and long-term follow-up to evaluate safety and efficacy.

Laser and anti-vascular endothelial growth factor treatment for drusenoid pigment epithelial detachment in age-related macular degeneration

This study aims to report the 12 months results of efficacy and safety of laser photocoagulation and anti-vascular endothelial growth factor (VEGF) injections for drusenoid pigment epithelial detachment (dPED). In this prospective study, patients with treatment naïve bilateral intermediate age-related macular degeneration, featuring dPED, with visual acuity ≤ 83 letters were enrolled. The study group received PASCAL laser (532 nm) along the periphery of the dPED, and the fellow eye served as a control group. To prevent complications of choroidal neovascularization, intravitreal anti-VEGF injections to laser treated eye were performed on a 3-month interval up to 1 year. Primary outcomes—drusen area, PED height—and secondary outcomes—best-corrected visual acuity (BCVA), contrast sensitivity, degree of metamorphopsia, NEI-VFQ 25, and fundus autofluorescence—were analyzed. Among 21 patients, a total of 20 patients satisfied the 12 months follow-up. Drusen area and PED height decreased significantly in the laser group, while no significant change appeared in the control group (74.1% vs. − 3.5%, P < 0.001; 76.6% vs. 0.1%, P < 0.001). Mean BCVA improved 4.6 letters in the laser group (vs. 1.1 letters in the control group, P = 0.019). As for safety, one study eye developed retinal pigment epithelial tear, and one control eye developed retinal angiomatous proliferation. Low energy laser photocoagulation and anti-VEGF injection in eyes with dPED showed some improvement in visual acuity. dPED regressed without developing center involving GA in the study eye, but a longer term follow-up is necessary to reveal the efficacy and safety of these treatments. The 2-year results of this study will be followed to reveal long term efficacy and safety of the treatment for dPED.

Sub-threshold nanosecond laser (SNL) treatment in intermediate AMD (IAMD)

The Laser intervention in early stages of age-related macular degeneration (LEAD) study (1) is a 36-month, multicenter, randomized, sham-controlled trial conducted from 2012-2015 of 292 participants with bilateral soft drusen, aka intermediate AMD (iAMD), who underwent q 6-month treatment with sub-threshold nanosecond laser (SNL) or sham treatment to the study eye. The primary efficacy outcome was the time to develop late AMD [geographic atrophy (GA) or choroidal neovascularization (CNV)] defined by multimodal imaging (MMI), which comprised spectral domain optical coherence tomography (SD-OCT), autofluorescence imaging (AF) and near-infrared reflectance imaging (NIR-R). Although progression to late AMD was not significantly slowed with SNL compared to sham for the entire group, posthoc analysis showed a significant benefit to those subjects without reticular pseudodrusen (RPD), and a worse outcome for those subjects with RPD, aka subretinal drusenoid deposits (SDD). SNL treatment may thus have a role in slowing progression for subjects without coexistent RPD/SDD and may be inappropriate in those with RPD/SDD. Further study is clearly warranted.

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.