A comparison of pattern and multifocal electroretinography in the evaluation of age-related macular degeneration and its treatment with photodynamic therapy

[Multifocal electroretinography in the diagnosis and monitoring of early and intermediate stages of age-related macular degeneration]

Multifocal electroretinography is a valuable diagnostic method for the objective localization and quantitative assessment of functional disorders of the central retina in age-related macular degeneration. It is used to detect early changes, monitor the course of the disease and treatment outcomes. In many cases, multifocal electroretinography is a more sensitive method for detecting functional disorders at the early/intermediate stage of age-related macular degeneration compared to morphological (optical coherence tomography) and subjective (visual acuity, perimetry) testing methods.

Recent Advances in Imaging Macular Atrophy for Late-Stage Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness worldwide. In late-stage AMD, geographic atrophy (GA) of dry AMD or choroidal neovascularization (CNV) of neovascular AMD eventually results in macular atrophy (MA), leading to significant visual loss. Despite the development of innovative therapies, there are currently no established effective treatments for MA. As a result, early detection of MA is critical in identifying later central macular involvement throughout time. Accurate and early diagnosis is achieved through a combination of clinical examination and imaging techniques. Our review of the literature depicts advances in retinal imaging to identify biomarkers of progression and risk factors for late AMD. Imaging methods like fundus photography; dye-based angiography; fundus autofluorescence (FAF); near-infrared reflectance (NIR); optical coherence tomography (OCT); and optical coherence tomography angiography (OCTA) can be used to detect and monitor the progression of retinal atrophy. These evolving diverse imaging modalities optimize detection of pathologic anatomy and measurement of visual function; they may also contribute to the understanding of underlying mechanistic pathways, particularly the underlying MA changes in late AMD.

The Clinical Spectrum and Disease Course of DRAM2 Retinopathy

Pathogenic variants in DNA-damage regulated autophagy modulator 2 gene (DRAM2) cause a rare autosomal recessive retinal dystrophy and its disease course is not well understood. We present two Slovenian patients harboring a novel DRAM2 variant and a detailed review of all 23 other patients described to date. Whole exome and whole genome sequencing were performed in the two patients, and both underwent ophthalmological examination with a 2-year follow-up. PubMed was searched for papers with clinical descriptions of DRAM2 retinopathy. Patient 1 was homozygous for a novel variant, p.Met1?, and presented with the acute onset of photopsia and retina-wide retinopathy at the age of 35 years. The patient was first thought to have an autoimmune retinopathy and was treated with mycophenolate mofetil, which provided some symptomatic relief. Patient 2 was compound heterozygous for p.Met1? and p.Leu246Pro and presented with late-onset maculopathy at the age of 59 years. On review, patients with DRAM2 retinopathy usually present in the third decade with central visual loss, outer retinal layer loss on optical coherence tomography and a hyperautofluorescent ring on fundus autofluorescence. Either cone–rod or rod–cone dystrophy phenotype is observed on electroretinography, reflecting the importance of DRAM2 in both photoreceptor types. Non-null variants can result in milder disease.

Decision making about healthcare-related tests and diagnostic test strategies. Paper 2: a review of methodological and practical challenges

OBJECTIVES

In this first of a series of five articles, we provide an overview of how and why healthcare-related tests and diagnostic strategies are currently applied. We also describe how our findings can be integrated with existing frameworks for making decisions that guide the use of healthcare-related tests and diagnostic strategies.

STUDY DESIGN AND SETTING

We searched MEDLINE, references of identified articles, chapters in relevant textbooks, and identified articles citing classic literature on this topic.

RESULTS

We provide updated frameworks for the potential roles and applications of tests with suggested definitions and practical examples. We also discuss study designs that are commonly used to assess tests' performance and the effects of tests on people's health. These designs include diagnostic randomized controlled trials and retrospective validation. We describe the utility of these and other currently suggested designs, which questions they can answer and which ones they cannot. In addition, we summarize the challenges unique to decision-making resulting from the use of tests.

CONCLUSION

This overview highlights current challenges in the application of tests in decision-making in healthcare, provides clarifications, and informs the proposed solutions.

The Role of mf-ERG in the Diagnosis and Treatment of Age-Related Macular Degeneration: Electrophysiological Features of AMD

INTRODUCTION

Age-related macular cegeneration (AMD) is the leading cause of visual dysfunction worldwide, affecting 9-25% of individuals between 65 and 75 years old.

METHODS

We have reviewed the published articles investigating the role of multifocal electroretinogram (mf-ERG) in the diagnosis and treatment of AMD.

RESULTS

Visual evoked potentials have revealed decreased amplitudes and higher latencies in patients with AMD, while the degeneration of photoreceptors and abnormalities of retinal pigment epithelium can be identified by electro-oculogram recordings. Moreover, ERG can detect the functional abnormalities observed in AMD and evaluate each therapeutic approach. The record of local electrophysiological responses coming from different retinal areas can be accurately performed by mfERG.

CONCLUSION

The accuracy of mfERG in detecting the degeneration of photoreceptors, as well the disturbances of macular function, could be useful both in the early diagnosis of AMD and the assessment of treatment efficacy.

The electroretinogram: a useful tool for evaluating age-related macular disease?

With an ageing population, the number of age-related macular disease (ARMD) cases will inevitably rise. This gives greater impetus for the need to identify the disease earlier and assess treatments to slow disease progression. Differing electroretinogram (ERG) modalities have been reviewed in relation to the objective assessment of retinal function in ARMD and for monitoring the effectiveness of clinical interventions. Conflicting results have been found with regard to the efficacy of ERG findings in the investigation of ARMD in previous years. The newer multifocal ERG paradigm provides spatial topographical information about retinal function in ARMD. It has shown promising results in monitoring effectiveness of clinical interventions and studies are continuing in this area. Better knowledge of retinal function in ARMD may lead to enhanced treatments at each phase of the disease.

The role of the ERG in the diagnosis and treatment of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is affecting an increasing number of people, with 2.95 million people estimated to be affected in the USA by 2020. Possible preventive agents, such as vitamins and supplements have been studied and new treatment options for AMD have been developed in recent years. What role does electrophysiology play as a sensitive outcome measure? The most commonly used tests are the full-field electroretinogram (ffERG) and the multifocal ERG (mfERG). Test results from patients with AMD and reduced central vision need special attention in respect to fixation pattern, age-matched control data, and retinal luminance. Advantages, disadvantages and limitations of techniques will be considered, together with a review of published studies.

Multifocal electroretinography as a predictor of maintenance of vision after photodynamic therapy for neovascular age-related macular degeneration

PURPOSE

To investigate the role of multifocal electroretinography (mfERG) in predicting the outcome of photodynamic therapy (PDT) for neovascular age-related macular degeneration (AMD).

METHODS

Participants underwent refraction protocol VA assessment using the ETDRS logMAR chart at 1 m, Contrast Sensitivity (CS) using the Pelli-Robson chart at 1 m, fundus fluorescein angiography (FA) and mfERGs in response to 19 segments. Response to PDT was binary (1 = the loss of less than 15 letters at 12 months, 0 = the loss of 15 letters or more) and was used as the dependent variable for logistic regression analysis.

RESULTS

Logistic regression modelling identified mfERG central segment amplitude, lesion size on FA, VA and CS as predictors of outcome (P = 0.05, 0.02, 0.01, 0.03). The model is stable and has excellent discriminability.

CONCLUSION

The outcomes of this study are particularly relevant to patients in the UK who are sometimes treated with PDT alone. A larger prospective study would facilitate development of an index to predict outcome of future treatments for AMD.

Deficits in the electroretinogram in neovascular age-related macular degeneration and changes during photodynamic therapy

PURPOSE

To describe the deficits in four electroretinography (ERG) modalities in patients with neovascular age-related macular degeneration (AMD). To describe the changes in these parameters during a course of verteporfin photodynamic therapy (PDT).

METHODS

Pattern (PERG), multifocal (mfERG) (19 segment simplified test protocol), flash ERG and flicker ERG were performed in patients with active neovascular AMD before PDT and compared to fellow eye controls using paired t-tests. Changes in ERG parameters during the 12 month treatment course were visualised using 95% confidence intervals of the median difference. The statistical significance of any changes was quantified using Wilcoxon signed ranks tests.

RESULTS

Fifty patients were recruited and followed. At presentation all ERG amplitudes were reduced with greater reductions in focal as opposed to global test protocols (P < 0.05). Over the 12 month course of PDT, PERG P50 amplitude showed a general downward trend and latency remained unchanged. mfERG p1 amplitude density showed an upward trend at six months before returning to baseline by 12 months. mfERG ring 2 amplitude density was significantly increased at 12 months compared to baseline (P = 0.010). Flicker ERG latency was significantly increased at six months compared to baseline (P = 0.015).

DISCUSSION

The simplified mfERG protocol was tolerated by this patient group, however, they found the full test protocol demanding. Large deficits in the retinal ERG function occur in neovascular AMD and involve retinal locations adjacent to as well as overlying choroidal neovascularisation (CNV). After PDT there is an improvement in electro-retinal function in retinal locations overlying the CNV.

RPE transplantation and its role in retinal disease

Retinal pigment epithelial (RPE) transplantation aims to restore the subretinal anatomy and re-establish the critical interaction between the RPE and the photoreceptor, which is fundamental to sight. The field has developed over the past 20 years with advances coming from a large body of animal work and more recently a considerable number of human trials. Enormous progress has been made with the potential for at least partial restoration of visual function in both animal and human clinical work. Diseases that have been treated with RPE transplantation demonstrating partial reversal of vision loss include primary RPE dystrophies such as the merTK dystrophy in the Royal College of Surgeons (RCS) rat and in humans, photoreceptor dystrophies as well as complex retinal diseases such as atrophic and neovascular age-related macular degeneration (AMD). Unfortunately, in the human trials the visual recovery has been limited at best and full visual recovery has not been demonstrated. Autologous full-thickness transplants have been used most commonly and effectively in human disease but the search for a cell source to replace autologous RPE such as embryonic stem cells, marrow-derived stem cells, umbilical cord-derived cells as well as immortalised cell lines continues. The combination of cell transplantation with other modalities of treatment such as gene transfer remains an exciting future prospect. RPE transplantation has already been shown to be capable of restoring the subretinal anatomy and improving photoreceptor function in a variety of retinal diseases. In the near future, refinements of current techniques are likely to allow RPE transplantation to enter the mainstream of retinal therapy at a time when the treatment of previously blinding retinal diseases is finally becoming a reality.