[Testing central retinal function with multifocal electroretinography before and after photodynamic therapy]

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.

Multifocal electroretinograms in age-related macular degeneration before and after photodynamic therapy

Purpose

To evaluate multifocal electroretinograms (mfERG) and macular retinal thickness before and after photodynamic therapy (PDT) for predominantly classic choroidal neovascularization (CNV) (classic type) and occult with no classic CNV (occult type).

Methods

Recording of mfERG and measurement of macular retinal thickness were performed before and after PDT in 19 patients (19 eyes) with the classic type and 24 (26 eyes) with the occult type. The evaluation items were the amplitude of the first negative wave (N1), the amplitude from the peak of the negative wave to that of the following positive wave (P1), and the peak latencies of the negative and positive waves.

Results

Compared with mfERG before PDT, that after PDT showed a significant decrease in the P1 latency in the central area (31.1±1.9 ms before and 29.6±1.6 ms after PDT) for the classic type and significant decreases in both the central (32.0±2.0 ms before and 30.5±2.4 ms after PDT) and peripheral (30.2±2.0 ms before and 29.5±2.0 ms after PDT) areas for the occult type. Optical coherence tomography showed significant decreases in macular retinal thickness in both groups (464 and 314 μm before and after PDT, respectively, for the classic type and 516 and 340 μm for the occult type).

Conclusions

After PDT, retinal function evaluated by mfERG improved for both the classic and occult types, and the recovery of P1 latency may be due to improvement in retinal edema.

Focal macular electroretinograms after photodynamic therapy combined with intravitreal bevacizumab

BACKGROUND

Retinal function is transiently depressed after photodynamic therapy (PDT) alone. One of the reasons for this functional impairment is a reduction of choroidal circulation caused by the PDT. The purpose of this study was to determine whether PDT combined with intravitreal bevacizumab (PDT+IVB) can reduce or prevent the transient impaired macular function. In addition, we examined whether a significant correlation existed between the changes in the focal macular electroretinograms (FMERGs), optical coherence tomography (OCT)-determined morphology, and changes in choroidal circulation.

METHODS

Thirty-eight eyes that were treated by full fluence PDT+IVB were studied. FMERGs, OCT, and indocyanine green angiography (ICGA) were performed before and after the PDT. The intensity of the diffuse fluorescence within the PDT site was measured by densitometry (I/N ratio).

RESULTS

The macula was significantly thinner 1 week after PDT+IVB (P < 0.01). The mean a- and b-wave amplitudes of the FMERGs were not significantly decreased 1 week after PDT+IVB. The mean b-wave amplitudes 3 months after PDT+IVB were significantly increased (P < 0.01). The I/N ratio of ICGA 3 months after PDT+IVB was 0.88 ± 0.1. The correlation between the FMERGs and I/N ratio was not significant.

CONCLUSION

The use of IVB with PDT mitigates the reduction of the FMERGs and reduces the macular thickness soon after PDT, regardless of the degree of impairment of choroidal circulation caused by PDT. Finally, the macular retinal function 3 months after PDT+IVB were better than that before the treatment.

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.

Focal macular electroretinograms after photodynamic therapy combined with posterior juxtascleral triamcinolone acetonide

PURPOSE

Retinal function is commonly depressed transiently after photodynamic therapy (PDT). Additional treatment may prevent this impaired retinal function. The purpose of this study was to determine the changes in the focal macular electroretinograms (FMERGs) after PDT combined with TA for age-related macular degeneration.

METHODS

Thirty-four eyes that were successfully treated by PDT with a posterior juxtascleral injection of TA were studied. FMERGs, optical coherence tomography, and indocyanine green angiography were performed before and after the PDT.

RESULTS

The mean amplitudes of the FMERGs were not significantly decreased 1 week after PDT with TA (P > 0.05). The mean ratio of the FMERG b-wave 1 week after PDT to that before PDT was 1.09, with an indistinct hypofluorescence at the site of the PDT (18 eyes), and the ratio was 0.91 in the eyes with a distinct hypofluorescence border (16 eyes; P < 0.05).

CONCLUSION

The combined use of TA with PDT mitigated the depression of retinal function soon after PDT. However, there were cases of severe choroidal hypoperfusion corresponding to the site of the laser spot that impaired retinal function in comparison to cases with mild hypoperfusion. Even with severe choroidal hypoperfusion, the deterioration in retinal function was relatively mild, with the b-wave FMERG reduced by only 10%.

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.

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

This study compares pattern electroretinography (PERG) and multifocal electroretinography (mfERG) measures in 13 patients with predominantly classic choroidal neovascularisation (CNV) associated with age-related macular degeneration (ARMD, 9/13 unilateral, 4/13 bilateral), assesses the usefulness of each test in monitoring disease progression, and identifies electrophysiological predictors of outcome following treatment with photodynamic therapy (PDT). PERG and mfERGs were recorded at presentation, 2 weeks post-treatment, and at 3 monthly intervals for 2 years. The PERG was detectable in 8/13 patients with unilateral disease; the mfERG was detectable in 12/13 patients. P50 and N95 amplitudes increased in 6/8 patients and mfERG p1 increased in 7/13 patients at 2 years. PERG amplitudes correlated strongly with mfERG amplitudes in patients with unilateral disease. PERG P50 and mfERG p1 amplitude correlated with visual acuity at 2 years (R = 0.68, R = 0.82, respectively). The largest PERG P50 and mfERG p1 amplitude difference between treated and fellow eyes of all the groups on initial visit was associated with a poor visual outcome (P50 64% difference; p1 29% difference) whereas those with the smallest P50 and p1 amplitude difference was associated with improved vision at 2 years (P50 30% difference; p1 21% difference). The PERG and mfERG provide an objective measure of central retinal function in the progression of ARMD. A detectable PERG on presentation was the single best indicator of improved function and visual acuity at 2 years. The mfERG demonstrated disease progression from central retina into the paramacular regions over 2 years. Patients with poor visual outcomes had the largest inter-ocular amplitude difference on presentation, suggesting that such patients may have a worse prognosis following treatment.

Different transitions of multifocal electroretinogram recordings between patients with age-related macular degeneration and polypoidal choroidal vasculopathy after photodynamic therapy

AIM

To compare and evaluate the transitions in retinal function after photodynamic therapy (PDT) between age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) using multifocal electroretinograms (mfERGs).

METHODS

10 eyes with choroidal neovascularisation (CNV) secondary to AMD and 11 eyes with CNV secondary to PCV were included in the study. mfERGs were recorded before PDT, and 1 week and 3 months after PDT. mfERG recordings were acquired by a Veris system (V.3.1.3) using a 103 hexagon stimulus. The first-order kernel was used to calculate amplitudes and latencies. Mean amplitudes and latencies from two central rings rated 0-4 degrees of visual angle were analysed and compared with each disease.

RESULTS

In AMD, the mean first negative peak (N1) amplitudes tended to decrease, and the mean first positive peak (N1P1) amplitudes reduced to significant levels (p = 0.047) 1 week after PDT. 3 months after PDT, there were no significant differences in the mean N1 and N1P1 amplitudes compared with pre-PDT values. In PCV, there were no significant changes in the mean N1 and N1P1 amplitudes 1 week after treatment. However, 3 months after PDT, mean amplitudes showed significant increases in N1 (p = 0.008) and N1P1 (p = 0.006) amplitudes compared with pre-PDT values.

CONCLUSIONS

mfERG recording transitions are different between patients with AMD and those with PCV. In patients with AMD, these results may show transient impairments in retinal function 1 week after PDT, but in those with PCV, the efficacy of PDT is superior to the impairment after PDT.

Dynamics of Retinal Function after Multiple Photodynamic Therapies in Age-Related Macular Degeneration: A Report of Cases

PURPOSE

To monitor retinal function after multiple laser treatments by photodynamic therapy (PDT) with the multifocal electroretinogram (mfERG) in age-related macular degeneration (AMD).

METHODS

Five eyes of five subjects with AMD were investigated before the first and 1 month after each of three PDT treatments. Function was assessed using the cone- and rod-mediated mfERG, high-contrast distance visual acuity, central visual fields and contrast sensitivity. For each subject the local first-order mfERG results before treatment were used as a template and fitted against the local post-treatment results (Matlab, Mathworks).

RESULTS

We found transient reduction of the cone- and rod-mediated amplitudes between the first and second treatments but stable or improved mfERG function in four of five eyes for the cone-mediated mfERG and in all eyes for the rod-mediated mfERG after three treatments. Visual acuities and contrast sensitivities remained stable between treatments in four and two eyes respectively, whereas visual fields showed substantially higher mean defects in two subjects after all treatments.

CONCLUSION

As found in previous studies of the cone-mediated mfERG after one PDT treatment, objective function was stabilized after multiple treatments in this case report. Similarly, although poor at baseline, rod-mediated function was not further compromised. Transiently reduced amplitudes after 1 month possibly reflected choroidal hypoperfusion. A larger sample size is needed to confirm if additional evaluation using electrophysiological criteria might be helpful in re-treatment decisions during PDT.

Klassifikation biomedizinischer Forschungsberichte als Grundlage evidenzbasierter Medizin in der Augenheilkunde

BACKGROUND

Evidence-based medicine requires careful appraisal of published data derived from experimental and clinical studies. Based on classification of biomedical research reports, evidence levels can be determined and recommendations for therapeutic decisions can be made.

METHODS

A classification system for clinical studies was developed. It was evaluated in classifying the reports published in Der Ophthalmologe during 2003-2004 (study design: descriptive cross-sectional study, case series).

RESULTS

In the 2-year interval, 70 longitudinal and 95 cross-sectional studies were published. The vast majority of the longitudinal studies were interventional cohort studies. Not considering case reports, 73% of the original articles were longitudinal prospective studies, 1% were retrospective (case-control) studies, and 26% were cross-sectional studies.

CONCLUSIONS

The study design of all published articles could be classified using the classification system. This classification system proves to be applicable in the context of clinical studies in ophthalmology and may be helpful in the process of critical appraisal of the literature and synthesis of clinical evidence and an evidence-based recommendation.

The use of subretinal triamcinolone acetonide in the management of neovascular age-related macular degeneration: a pilot study

BACKGROUND

We conducted this study to investigate the toxicity and efficacy of pars plana vitrectomy combined with a single dose of sub-retinally administered triamcinolone acetonide (4 mg) in patients with subfoveal choroidal neovascular membranes secondary to age-related macular degeneration (AMD).

METHODS

The important eligibility criteria included eyes with recent and progressive onset of decreased vision (<or= 20/400) secondary to active subfoveal choroidal neovascularization secondary to AMD demonstrable on fluorescein angiography, in which subretinal hemorrhage accounted for < 25% of the area of the choroidal neovascular complex. Eligible patients were offered vitrectomy surgery combined with subretinal injection of 0.1 mL of triamcinolone acetonide (40 mg/mL) followed by air-fluid exchange. Two eyes of 2 patients were enrolled and followed for 28 and 35 months with regular and serial complete ophthalmologic examinations, fluorescein and indocyanine green videoangiography, and multifocal electro-retinography. The primary outcome measures were best-corrected visual acuity, changes in the fluorescein angiographic area and in the greatest linear dimension of leakage of the choroidal neovascular complex, and changes in amplitude and latency of the multifocal electroretinogram (ERG).

RESULTS

Patient 1 sustained a limited subretinal hemorrhage intraoperatively that cleared spontaneously over approximately 3 months, as well as a rise in intraocular pressure that required the use of 2 topical medications to control. Patient 2 demonstrated progression of his nuclear sclerosis and posterior subcapsular lens changes over the 35 months of follow-up. Best-corrected visual acuity improved from 20/400 to 20/200 in patient 1 and improved from counting fingers to 20/320 in patient 2. For patient 1, the area of the neovascular complex increased from 4.5 mm2 at baseline to 7.2 mm2 at the 6-month follow-up; for patient 2, this increase was from 6.2 mm2 to 8.4 mm2. Over the same interval, the greatest linear dimension increased from 3.8 mm to 4.8 mm for patient 1 and from 4.1 mm to 4.8 mm for patient 2. With respect to the multifocal ERG, the response density increased in the first 4 months for patient 1 and declined marginally thereafter. For patient 2, the electro-retinal response density function was stabilized for a 5-month period but declined and stabilized thereafter.

INTERPRETATION

Our results from this pilot study suggest that vitrectomy combined with subretinal injections of 0.1 mL of triamcinolone acetonide (40 mg/mL) and air-fluid exchange is easily accomplished. Although some complications were encountered, these did not appear to be prohibitive. A salutary effect was clearly demonstrated, not unlike the course seen with photodynamic therapy. Further study, perhaps in combination with other antiangiogenic agents, is warranted.

Objective functional assessment of age‐related maculopathy: a special application for the multifocal electroretinogram

This paper gives a brief review of methods that assess objectively function in age-related maculopathy (ARM) with emphasis on a newer method, the multifocal electroretinogram (mfERG). In contrast to other electrophysiological tests, such as the full-field and focal electroretinogram (ERG) or the electro-oculogram (EOG), which measure summed responses from various cells from larger areas of the retina, the multifocal electroretinogram maps function locally with a resolution as small as four degrees within the central 30 degrees. By using different paradigms it can measure local cone- and rod-mediated functional impairment at early and late stages of ARM. This improved mapping and higher resolution of the posterior pole compared to other objective methods might lead to earlier detection of ARM. Its usefulness has been demonstrated in documenting the effects of treatment after established laser treatments, such as photodynamic therapy (PDT) and in documenting function after retinal pigment epithelial transplantation, a possible future treatment in late neovascular ARM.

Transient reduction in retinal function revealed by multifocal electroretinogram after photodynamic therapy

PURPOSE

To evaluate the early changes in retinal function after photodynamic therapy (PDT) by multifocal electroretinogram (mfERG).

DESIGN

Prospective interventional case series.

METHODS

Seventeen eyes from 17 patients scheduled for standard PDT with verteporfin were prospectively recruited. Patients' diagnoses included choroidal neovascularization (CNV) secondary to age-related macular degeneration, idiopathic CNV, myopic CNV, polypoidal choroidal vasculopathy, and central serous chorioretinopathy. Serial mfERG recordings were performed before PDT, and at 4 days, 2 weeks, and 1 month after PDT. The first-order kernel N1 and P1 mfERG response from the central 0 to 7 degrees and peripheral 7 to 25 degrees were grouped and analyzed. The mean response amplitudes and peak latencies of the mfERG recordings were compared longitudinally.

RESULTS

There were statistically significant reductions in the mean N1 response amplitude for the central group at 4 days (P =.007) and 2 weeks after PDT (P =.024), in the mean P1 response amplitude for both the central (P =.006) and peripheral (P =.013) groups at 4 days, and for the central group at 2 weeks after PDT (P =.017). There were also statistically significant increases in the mean P1 response latencies at 4 days (P =.004) and at 2 weeks (P =.018) after PDT for the central group and at 4 days after PDT (P =.026) for the peripheral group. At 1 month after PDT, no significant differences in the N1 and P1 mean response amplitudes and peak latencies were observed compared with pre-PDT mfERG.

CONCLUSIONS

Transient impairments in retinal function for as long as 2 weeks after PDT were noticed by reduction in response amplitudes and a delay in peak latencies of mfERG. These findings may explain the common adverse event of subjective visual disturbance early after PDT with normal findings in visual acuity and ophthalmoscopy.