Fixation stability and implication for multifocal electroretinography in patients with neovascular age-related macular degeneration after anti-VEGF treatment

Additional measures of macular function beyond visual acuity

PURPOSE

Visual function is a complex process in which external visual stimuli are interpreted. Patients with retinal diseases and prolonged follow-up times may experience changes in their visual function that are not detected by the standard visual acuity measure, as they are a result of other alterations in visual function. With the advancement of different methods to evaluate visual function, additional measurements have become available, and further standardization suggests that some methods may be promising for use in clinical trials or routine clinical practice. The objectives of this article are to review these additional measurements and to provide guidance on their application.

METHODS

The Vision Academy's membership of international retinal disease experts reviewed the literature and developed consensus recommendations for the application of additional measures of visual function in routine clinical practice or clinical trials.

RESULTS

Measures such as low-luminance visual acuity, contrast sensitivity, retinal fixation and microperimetry, and reading performance are measures which can complement visual acuity measurements to provide an assessment of overall visual function, including impact on patients' quality of life. Measures such as dark adaptation, color vision testing, binocular vision testing, visual recognition testing, and shape discrimination require further optimization and validation before they can be implemented in everyday clinical practice.

CONCLUSION

Additional measurements of visual function may help identify patients who could benefit from earlier diagnosis, detection of disease progression, and therapeutic intervention. New and additional functional clinical trial endpoints are required to fully understand the early stages of macular disease, its progression, and the response to treatment.

Effect of eccentric fixation on the steady-state pattern electroretinogram

PURPOSE

The steady-state pattern electroretinogram (ssPERG) is used to assess retinal ganglion cell function in a variety of research contexts and diagnostic applications. In certain groups of patients or study participants, stable central fixation of the stimulus is not guaranteed. The present study aimed at assessing the effects of misfixation on the ssPERG response to checkerboard reversal stimuli.

METHODS

Using two check sizes (0.8° and 15°), we compared ssPERG responses for several amounts of fixation deviation, ranging from 0° to 19° horizontally and from 0° to 14° diagonally. The stimulus area extended to 15° eccentricity, stimulus reversal rate was 15/s.

RESULTS

Up to around 7° eccentricity, there was no sizable effect of fixation deviation under most conditions. Effects were somewhat larger for nasal than for temporal deviation, in particular for small checks. Diagonal deviation was associated with a response to luminance onset/offset at 7.5 Hz (subharmonic of the reversal rate), most prominently when the interior of a large check was fixated.

CONCLUSION

Generally, moderate inaccuracies of fixation do not have a sizable effect on ssPERG amplitude. However, with large checks, the luminance response has to be considered.

Electrophysiological evaluation and 18-month follow-up of two regimens with aflibercept for neovascular age-related macular degeneration

Purpose

To compare two aflibercept treatment regimens and the electrophysiological outcome concerning cone and rod function in age-related macular degeneration (nAMD) over 18 months.

Methods

41 patients with treatment-naïve nAMD were randomized 1:1 to either arm 1 or 2. Arm 1 received three consecutive monthly aflibercept injections, followed by bimonthly treatment until week 52. Thereafter, a treat-and-extend (TAE) regimen was applied. Arm 2 was treated according to a TAE protocol throughout the 18-month follow-up. We assessed visual acuity (VA), central retinal thickness (CRT), injection rate and interval, and evaluated cone and rod function with full-field and multifocal electroretinography (ffERG, mERG).

Results

There were no statistically significant differences in mean baseline VA, lesion type, age, gender, or symptom duration between the two arms. During the 18-month follow-up, mean VA improved in arm 1 (n = 19) from 63.5 ± 10.5 to 69.1 ± 9.2 letters; p = 0.098; and in arm 2 (n = 20) from 66.8 ± 13.6 to 73.9 ± 9.0 letters; p = .002. In both arms, mean CRT was significantly reduced; p < 0.000. At month 18, we found no significant difference in the number of injections or injection intervals between groups. Arm 1 had received 11.3 ± 1.7 injections vs. 10.9 ± 2.0 in arm 2. The mean injection interval was 9.2 ± 3.4 weeks vs. 9.5 ± 3.1, with 52% (n = 10) on the maximum 12-week interval in arm 1, and 50% (n = 10) in arm 2. The combined rod-cone a-wave amplitude significantly decreased over time; p = 0.043. The isolated rod b-wave amplitude showed a statistically significant decline; p = 0.026. The overall mERG amplitude and implicit time remained unchanged over time; p = 0.878 vs. p = 0.922. The central ring 1 mERG amplitude improved; p = 0.041, with an unaffected implicit time.

Conclusions

After 18 months, both treatments arms have received a similar number of injections at comparable intervals. Electrophysiological evaluation shows no signs of toxicity concerning cone function. But ffERGs for the combined and isolated rod response have declined, possibly reflecting either toxic effects of the drug to rods or the natural course of the disease itself.

Correlation of macular sensitivity measures and visual acuity to vision-related quality of life in patients with age-related macular degeneration

Background

Visual acuity is commonly used as a functional outcome measure in patients with age-related macular degeneration (AMD), despite having a weak correlation with self-perceived visual quality of life. Microperimetry is a useful method of detecting loss of macular function. We wanted to investigate the relationship between these two objective visual outcome measures and subjective vision-related quality of life, finding out which objective measure is more patient-relevant.

Methods

Fifty-one consecutive patients with AMD were recruited to the study. Participants were required to complete the Visual Function Questionnaire 39, the Early Treatment Diabetic Retinopathy Study visual acuity examination and a microperimetry assessment using the Micro Perimeter 3. One patient withdrew consent and seven patients dropped out due to cooperation difficulties under microperimetry. Forty-three patients with AMD were included in the study: twenty-eight patients with late AMD (exudative AMD) and fifteen patients with early (non-exudative) AMD. The right eye was included as standard, as was the eye with the best-corrected visual acuity.

Results

There was a higher correlation between vision-related quality of life and macular sensitivity (r = 0.458; p = 0.014) than between vision-related quality of life and visual acuity (r = 0.446; p = 0.018) in patients with late AMD. There was a positive correlation between vision-related quality of life and macular sensitivity in patients with early AMD (r = 0.542; p = 0.037) while the correlation between vision-related quality of life and visual acuity in these patients was not statistically significant. Composite score (r = 0.469; p = 0.012) correlated highest with the nasal outer macular sub-region and near-distance activities score (r = 0.652; p < 0.001) correlated highest with the nasal inner macular sub-region in patients with late AMD. Correlations between composite score and macular sub-regions in patients with early AMD were not significant, but near-distance activities score correlated with the nasal outer macular sub-region in these patients (r = 0.469; p = 0.012).

Conclusions

Macular sensitivity as measured using microperimetry correlates with vision-related quality of life in early AMD and in late AMD, showing it to be a patient-relevant outcome measure. Furthermore, the nasal sub-regions of the macula appear to be preferred retinal loci in patients with AMD.

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Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01901-x.

Full-field Electroretinography in Age-related Macular Degeneration: can retinal electrophysiology predict the subjective visual outcome of cataract surgery?

PURPOSE

Predicting the visual gain from cataract surgery when the main cause of vision loss is age-related macular degeneration may be difficult and warrants the need for an objective predictor of subjective outcome. Full-field electroretinography is an objective measure of overall retinal function. We therefore wanted to study if full-field electroretinography can predict subjective visual outcome using visual function questionnaire.

METHODS

Thirty-one patients with age-related macular degeneration operated for bilateral cataract underwent full-field electroretinography preoperatively. Full-field electroretinography was performed according to International Society for the Clinical Electrophysiology of Vision standards using a Ganzfeld bowl (RETI-port/scan 21, Roland, Berlin) and Dawson-Trick-Litzkow fibre electrodes. Vision-related quality of life was measured using the National Eye Institute Visual Function Questionnaire-39 before first-eye surgery and 4.12 ± 2.11 months after second-eye surgery.

RESULTS

Mean change in composite visual function questionnaire score after cataract surgery was 9.2 ± 11.9. The patients were divided into three groups: visual function questionnaire composite score increase >10 (n = 17); no change (n = 8); and decrease (n = 6). In the dark-adapted full-field electroretinography responses, we found a significant difference between the three groups in the 0.01 b-wave amplitude (p = 0.05), the 10.0 b-wave amplitude (p = 0.04) and a near-significant difference in 3.0 a-wave amplitude (p = 0.09). Other dark-adapted responses (the 3.0 b-wave and 10.0 a-wave) did not show any significant differences between the three groups, and neither did the light-adapted responses.

CONCLUSION

Patients with low dark-adapted responses on full-field electroretinography preoperatively experience a decrease in subjective vision-related quality of life, suggesting that maintained rod function before cataract surgery may be important.

The area of fixation covaries with short-term changes in visual acuity after anti-vascular endothelial growth factor treatment in patients with diabetic macular oedema

PURPOSE

Diabetic maculopathy can be treated with intravitreal injection of vascular endothelial growth factor (VEGF) inhibitors. However, the therapy is not effective in all patients, and it would be desirable to have parameters for differentiating patients who will benefit from treatment from those who will not. Retinal fixation has been shown to be impaired in patients with low visual acuity (VA) secondary to macular disease, but the changes in fixational eye movements after anti-VEGF treatment for diabetic maculopathy have not been investigated.

METHODS

Retinal fixation was studied in 29 patients with diabetic macular oedema before three monthly anti-VEGF injections, and 1 and 4 months after the last injection. The change in VA was correlated with changes in area, frequency, amplitude and total number of fixational saccades.

RESULTS

During three monthly injections, best-corrected visual acuity (BCVA) increased from (mean ± SD) 74.0 ± 11.5 Early Treatment Diabetic Retinopathy Study (ETDRS) letters to 78.3 ± 9.8 ETDRS letters, (p = 0.003) and central retinal thickness (CRT) decreased from (mean ± SD) 441.7 ± 107.0 μm to 339.5 ± 74.2 μm, (p = <0.0001), which was followed by the opposite changes after treatment (BCVA reduced nonsignificantly to 77.5 ± 10.4 ETDRS letters (p = 0.06), and CRT increased to 393.0 ± 9.8 μm, p = <0.0001). Both improvement and worsening of BCVA correlated with the fixation area (r²  = 0.28, p = 0.003 and r²  = 0.14, p = 0.045, respectively), but only improvement of BCVA correlated with the frequency (r²  = 0.15, p = 0.037) and total number of saccades (r²  = 0.18, p = 0.02). BCVA showed no correlation with the amplitude and most frequently occurring saccade amplitude.

CONCLUSION

Fixational eye movements may be used to monitor short-term effects of anti-VEGF treatment on diabetic macular oedema. Future studies should aim at investigating a possible predictive value of fixational eye movements for visual function in the long term.