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

Age-Related Macular or Retinal Degeneration?

Age-related macular degeneration (AMD) is an eye disease that leads to progressive vision loss. Its prevalence has been increasing due to population aging. Previously, it was commonly believed that the disease affects the central retina, that is, the macula. However, recent studies have shown that it also involves the peripheral retina. Novel imaging techniques revealed various degenerative lesions that extend beyond the central macula. While their prevalence remains unknown, they seem to be more frequent in patients with late AMD. These findings suggest that the term "age-related retinal dysfunction" might be more adequate to describe some cases of AMD. They also raise the question about the role of electroretinography (ERG) as an objective measure of retinal function. The most common types of ERG tests used in AMD are multifocal (mfERG) and full-field ERG (ffERG). mfERG is more sensitive to macular changes, but the test is difficult to perform when fixation is unstable. On the other hand, ffERG reflects the function of the entire retina, not only the macular area. It helps assess the impact of peripheral retinal lesions and overall retinal function in patients with AMD. As ffERG results are normal in early-stage AMD, any abnormalities indicate that the disease is more severe and affects the entire retina. Anti-vascular endothelial growth factor injections improve retinal function in patients with neovascular AMD, as demonstrated by an increase in their ERG responses. More research is needed to assess the association between local and general retinal dysfunction. In this review, ffERG findings in patients with AMD are described and the usefulness of ffERG is discussed based on previous studies and cases from our own clinical practice.

The evolution of clinical guidelines for antimicrobial photodynamic therapy of skin

Antimicrobial photodynamic therapy has become an important component in the treatment of human infection. This review considers historical guidelines, and the scientific literature to envisage what future clinical guidelines for treating skin infection might include. Antibiotic resistance, vertical and horizontal infection control strategies and a range of technologies effective in eradicating microbes without building up new resistance are described. The mechanism of action of these treatments and examples of their clinical use are also included. The research recommendations of NICE Guidelines on the dermatological manifestations of microbial infection were also reviewed to identify potential applications for PDT. The resistance of some microbes to antibiotics can be halted, or even reversed through the use of supplementary drugs, and so they are likely to persist as a treatment of infection. Conventional PDT will undoubtedly continue to be used for a range of skin conditions given existing healthcare infrastructure and a large evidence base. Daylight PDT may find broader antimicrobial applications than just Acne and Cutaneous Leishmaniasis, and Ambulatory PDT devices could become popular in regions where resources are limited or daylight exposure is not possible or inappropriate. Nanotheranostics were found to be highly relevant, and often include PDT, however, new treatments and novel applications and combinations of existing treatments will be subject to Clinical Trials.

EVALUATION OF SHORT-TERM OUTCOMES OF INTRAVITREAL AFLIBERCEPT INJECTIONS FOR AGE-RELATED MACULAR DEGENERATION USING FOCAL MACULAR ELECTRORETINOGRAPHY

PURPOSE

To evaluate the relationship between morphological changes and functional improvements assessed using focal macular electroretinograms after intravitreal aflibercept (IVA) injections in eyes with wet age-related macular degeneration.

METHODS

The clinical records of 42 eyes of 42 consecutive patients with naive, wet age-related macular degeneration received 3 monthly IVA were reviewed. The best-corrected visual acuity, central foveal thickness, outer retinal thickness, inner retinal thickness at baseline and 1 month after each IVA, and focal macular electroretinograms at baseline and 1 month after the first and third IVA were compared.

RESULTS

Best-corrected visual acuity was improved after the third IVA (P = 0.0091). Central foveal thickness and outer retinal thickness showed decreases after every IVA (P < 0.001, respectively). Inner retinal thickness showed a decrease after the second IVA (P = 0.002), after and third IVA (P = 0.001). On focal macular electroretinograms, a- and b-wave amplitudes showed increases after the third IVA (P = 0.0028, P = 0.0012, respectively). Significant correlations were observed between best-corrected visual acuity and central foveal thickness, a-wave amplitude and outer retinal thickness, and b-wave amplitude and inner retinal thickness changes after the third IVA.

CONCLUSION

All parameters significantly recovered after three monthly IVA, with a correlation between functional improvements and morphological changes.

Testing the clinical value of multifocal electroretinography and microperimetry and the effects of intravitreal therapy with ranibizumab on macular function in the course of wet age-related macular degeneration: a 1-year prospective study

Purpose

To investigate the clinical value of multifocal electroretinography (mfERG) and microperimetry and the effects of intravitreal therapy with ranibizumab (Lucentis^®) on macular function in the course of neovascular age-related macular degeneration (nAMD).

Materials and methods

We conducted a prospective single-arm interventional cohort study with 20 nAMD patients older than 50 years. Examinations were scheduled monthly for 1 year during intravitreal therapy with ranibizumab. The examinations included mfERG, microperimetry, spectral domain optical coherence tomography, and best-corrected visual acuity using ETDRS score.

Results

During the 12-month observation period, a significant positive linear correlation between the logarithm of minimum angle of resolution (logMAR) and scotoma area (r=0.28, 95% confidence interval [CI] 0.21–0.35), between logMAR and fovea thickness in optical coherence tomography (r=0.11, 95% CI 0.04–0.2), and a significant negative correlation between logMAR and mfERG (−0.37, 95% CI −0.43 to −0.31) were observed. A significant ranibizumab effect on logMAR was found (P=0.0065). From a total of 25 relapses, 14 were able to be predicted correctly by mfERG P₁ decrease in the preceding month. However, there was no statistically significant relation between prediction and observed relapses (Fisher’s exact test, P=0.6726).

Conclusion

Our results indicate a possible role of mfERG and microperimetry in the monitoring of macular function and prediction of recurrence during intravitreal pharmacotherapy in wet AMD.

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.

Preliminary study on electrophysiological changes after cellular autograft in age-related macular degeneration

Evolving atrophic macular degeneration represents at least 80% of all macular degenerations and is currently without a standardized care. Autologous fat transplantation efficacy was demonstrated by several studies, as these cells are able to produce growth factors. The aim of the work was to demonstrate possible therapeutic effect of the joined suprachoroidal graft of adipocytes, adipose-derived stem cells (ADSCs) in stromal vascular fractions (SVFs) of adipose tissue, and platelet-rich plasma (PRP). Twelve eyes in 12 dry age-related macular degeneration (AMD) patients, aged 71.25 (SD ± 6.8) between 62 and 80 years, were analyzed. A complete ocular evaluation was performed using best corrected visual acuity (BCVA), retinographic analysis, spectral-domain optical coherence tomography, microperimetry, computerized visual field, and standard electroretinogram (ERG). Each eye received a cell in graft between choroid and sclera of mature fat cells and ADSCs in SVF enriched with PRP by means of the variant second Limoli (Limoli retinal restoration technique [LRRT]). In order to test if the differences pre- and post-treatment were significant, the Wilcoxon signed-rank test has been performed. Adverse effects were not reported in the patients. After surgery with LRRT, the most significant increase in the ERG values was recorded by scotopic rod-ERG (answer coming from the rods), from 41.26 to 60.83 μV with an average increase of 47.44% highly significant (P < 0.05). Moderately significant was the one recorded by scotopic maximal ERG (answer coming from the rods and cones), from 112.22 to 129.68 μV with an average increase of 15.56% (P < 0.1). Cell-mediated therapy based on growth factors used appears interesting because it can improve the retinal functionality responses in the short term. The ERG could, therefore, be used to monitor the effect of cell-mediated regenerative therapies.

Improvement of retinal function in early age-related macular degeneration after lutein and zeaxanthin supplementation: a randomized, double-masked, placebo-controlled trial

PURPOSE

To examine the effects of lutein and zeaxanthin supplementation on retinal function using multifocal electroretinograms (mfERG) in patients with early age-related macular degeneration (AMD).

DESIGN

Randomized, double-masked, placebo-controlled trial.

METHODS

One hundred eight subjects with early AMD were randomly assigned to receive 10 mg/d lutein (n = 27), 20 mg/d lutein (n = 27), 10 mg/d lutein plus 10 mg/d zeaxanthin (n = 27), or placebo (n = 27) for 48 weeks. Thirty-six age-matched controls without AMD were also enrolled to compare baseline data with early AMD patients. MfERG responses and macular pigment optical densities (MPODs) were recorded and analyzed at baseline and at 24 and 48 weeks.

RESULTS

There were significant reductions in N1P1 response densities in ring 1 to ring 3 in early AMD patients compared with the controls (P < .05), whereas neither N1P1 response densities in ring 4 to ring 6 nor P1 peak latencies significantly changed. After 48-week supplementation, the N1P1 response densities showed significant increases in ring 1 for the 20 mg lutein group and for the lutein and zeaxanthin group, and in ring 2 for the 20 mg lutein group. The increases in MPOD related positively to the increases in N1P1 response density in ring 1 and ring 2 for nearly all active treatment groups. N1P1 response densities in ring 3 to ring 6 or P1 peak latencies in all rings did not change significantly in any group.

CONCLUSION

Early functional abnormalities of the central retina in the early AMD patients could be improved by lutein and zeaxanthin supplementation. These improvements may be potentially attributed to the elevations in MPOD.

Transitions of multifocal electroretinography in patients with age-related macular degeneration after combination therapy with photodynamic therapy and intravitreal bevacizumab

To compare the differences in color Doppler imaging (CDI) and pattern visual evoked potential (P-VEP) examinations between normal tension glaucoma (NTG) and hypertension primary open angle glaucoma (HTG) patients, and investigate the relation between flow velocities measured by CDI and P-VEP examination in NTG and HTG patients. Sixty NTG patients, 66 HTG patients and 44 control subjects underwent CDI evaluation of the ophthalmic artery (OA), short posterior ciliary artery (SPCA) and central retinal arteries (CRA). The peak systolic velocities (PSV) and end-diastolic velocities (EDV) and resistive index (RI) of all retrobulbar vessels were measured. The latency and amplitude of P100 in P-VEP were recorded from the three groups. The differences of CDI and P-VEP parameters among NTG group, HTG group and control group were compared by one-way analysis of variance. The correlations between CDI parameters and visual field indices, P-VEP and visual field indices, P-VEP and CDI parameters in NTG and HTG patients were evaluated by Pearson's correlation analysis. NTG and HTG patients had the lower EDV and higher RI in the OA, CRA and SPCA comparing with that of control subjects. NTG and HTG patients also had lower PSV in OA and CRA comparing with that of control subjects. There was no significant difference in the blood flow velocities and RI of all retrobulbar vessels between NTG and HTG patients. The latency of P100 in VEP delayed and the amplitude of P100 decreased in the NTG and HTG patients comparing with that of the control group. There was no significant difference in the latency and amplitude of P100 between the NTG and HTG patients. The RI of OA and SPCA were negatively correlated with the mean deviation (MD) values in the NTG and HTG patients. The RI of OA was positively correlated with the PSD value in the NTG and HTG patients. The MD values in the NTG and HTG patients were negatively correlated with the latency time of P100. The RI of OA was positively correlated with the latency time of P100 in NTG and HTG patients. The RI of OA was negatively correlated with the amplitude of P100 in HTG patients. No significant difference was found in the parameters of CDI and P-VEP between NTG and HTG patients. The certain parameters of CDI were correlated with P-VEP parameters in NTG and HTG patients.

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.

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.