Predicting Visual Acuity From Visual Field Sensitivity in Age-Related Macular Degeneration

Frequency-of-seeing curves (psychometric functions) for perimetric stimuli in age-related macular degeneration

PURPOSE

Frequency-of-seeing (FoS) curves (psychometric functions) for perimetric stimuli have been widely used in computer simulations of new visual field test procedures. FoS curves for age-related macular degeneration (AMD) are not available in the literature and are needed for the development of improved microperimetry test procedures, which are of particular interest for use as clinical trial endpoints.

METHODS

Data were refitted from a previous study to generate FoS curves for 20 participants with AMD, each tested at nine locations within the central 10°. Stimulus parameters, background luminance and dB scale were matched to the MAIA-2 microperimeter, and stimuli were presented in a method of constant stimuli to build up FoS curves over multiple runs. FoS curves were fitted with a modified cumulative Gaussian function. The relationship between sensitivity and slope of fitted FoS curves was modelled by robust linear regression, producing models both with and without an eccentricity parameter.

RESULTS

FoS curves were satisfactorily fitted to data from 174 visual field locations in 20 participants (age 65-83 years, 11 female). Each curve was made up of a median of 243 (range 177-297) stimulus presentations over a median of 12 (range 9-32) levels. Median sensitivity was 25.5 dB (range 3.8-31.4 dB). The median slope (SD of fitted function) was 1.6 dB (range 0.5-8.5 dB). As in previous studies of other conditions, the slope of fitted FoS curves increased as sensitivity decreased (p < 0.001).

CONCLUSIONS

FoS are provided for participants with AMD, as well as models of the relationship between sensitivity and slope. These fitted models and data may be useful for computer simulation studies of microperimetry procedures. Full details of the fitted curves are provided as supporting information.

Should clinical automated perimetry be considered for routine functional assessment of early/intermediate age-related macular degeneration (AMD)? A systematic review of current literature

Purpose

There is growing interest in functional testing for early/intermediate age‐related macular degeneration (iAMD). However, systematic evaluation of existing clinical functional tests is lacking. This systematic review examines evidence for using clinical automated perimetry in routine assessment of early/iAMD.

Recent findings

PubMed, Web of Science Core Collection, and Embase were searched from inception to October 2020 to answer, is there evidence of visual field defects in early/iAMD, and if so, are early/iAMD visual field defects linked to real‐world patient outcomes? Articles using clinical automated perimetry (commercially accessible and non‐modified devices/protocols) were included. Microperimetry was excluded as this has yet to be incorporated into clinical guidelines. The primary outcome was global visual field indices including mean deviation (MD), pattern standard deviation (PSD), mean sensitivity (MS) and frequency of defects. The secondary outcome was any real‐world patient outcome including quality of life and/or activities of daily living indices. Twenty‐six studies were eligible for inclusion and all studies were observational. There was consistent evidence of worsened MD, PSD, MS and frequency of defects for early/iAMD compared to normal eyes under photopic, low‐photopic and scotopic conditions. Meta‐analysis of studies using standard automated perimetry (SAP) under photopic conditions revealed worsened MD (−1.52dB [−2.27, −0.78 dB]) and MS (−1.47dB [−2, −0.94 dB]) in early/iAMD compared to normal eyes, representing large statistical effect sizes but non‐clinically meaningful reductions. There was insufficient data for meta‐analyses regarding other clinical automated perimetry protocols. Only one study assessed a real‐world patient outcome (on‐road driving performance), with no significant link to visual field outcomes in early/iAMD.

Summary

Significant reduction of global visual field indices is present in early/iAMD, but not clinically meaningful using SAP under photopic conditions. Translational relevance of visual field outcomes to patient outcomes in early/iAMD remains unclear. Thus, SAP under photopic conditions is unlikely to be useful for routine assessment of early/iAMD.

CLINICAL UTILITY OF MORPHOFUNCTIONAL CORRELATION OF MICROPERIMETRY AND OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

To demonstrate the clinical and research value of a simplified technique enabling alignment of functional microperimetry data with retinal structure imaged by eye-tracked optical coherence tomography (OCT) in eyes with macular disease.

METHODS

Normal and diseased eyes underwent sequential Spectralis OCT macular raster scans and Macular Integrity Assessment microperimetry using both standard central 10° analysis and custom scan patterns. The microperimetry data were imported into Spectralis research software program, which was automatically registered to the scanning laser ophthalmoscopy near-infrared reflectance image obtained during OCT acquisition. The OCT B-scans were directly correlated with the microperimetry data so that retina sensitivity and retinal microstructure at corresponding points could be evaluated simultaneously.

RESULTS

Seventy eyes of 41 patients (110 studies) aged 22 years to 95 years (mean 63.5 ± 18.0 years) with both normal and pathologic macular changes were included. The mean Macular Integrity Assessment retina sensitivity of all 110 studies was 22.2 ± 4.9 (range: 0.1-30.3). Retinal sensitivity showed good correspondence in structural changes seen on OCT B-scans.

CONCLUSION

We demonstrate a practical method to align retina sensitivity data to anatomical tomographic findings. This technique provides data not obtainable with standard visual acuity measures.

Fundus-controlled perimetry (microperimetry): Application as outcome measure in clinical trials

Fundus-controlled perimetry (FCP, also called 'microperimetry') allows for spatially-resolved mapping of visual sensitivity and measurement of fixation stability, both in clinical practice as well as research. The accurate spatial characterization of visual function enabled by FCP can provide insightful information about disease severity and progression not reflected by best-corrected visual acuity in a large range of disorders. This is especially important for monitoring of retinal diseases that initially spare the central retina in earlier disease stages. Improved intra- and inter-session retest-variability through fundus-tracking and precise point-wise follow-up examinations even in patients with unstable fixation represent key advantages of these technique. The design of disease-specific test patterns and protocols reduces the burden of extensive and time-consuming FCP testing, permitting a more meaningful and focused application. Recent developments also allow for photoreceptor-specific testing through implementation of dark-adapted chromatic and photopic testing. A detailed understanding of the variety of available devices and test settings is a key prerequisite for the design and optimization of FCP protocols in future natural history studies and clinical trials. Accordingly, this review describes the theoretical and technical background of FCP, its prior application in clinical and research settings, data that qualify the application of FCP as an outcome measure in clinical trials as well as ongoing and future developments.

Does functional assessment predict everyday visual functioning? Visual function testing and quality of life in mild/moderate age-related macular degeneration

PURPOSE

To prospectively assess correlations between self-reported vision-related quality of life (VR-QoL) and clinical functional assessments in mild/moderate age-related macular degeneration (AMD).

METHODS

Cross-sectional analysis of 64 participants with bilateral mild/moderate AMD. Microperimetry (MP), flicker perimetry (FP), multifocal electroretinogram (mfERG) findings, best-corrected visual acuity (BCVA) and the National Eye Institute Visual-Function Questionnaire-25 (NEI VFQ-25) were assessed for correlation between clinical testing results and NEI VFQ-25 findings.

RESULTS

MP findings in the better eye were weakly correlated with NEI VFQ-25 subscales for colour, general, near and distance vision (p < 0.05 and R² < 0.3 for all). FP findings and mfERG response density were not correlated with any subscale, apart from mfERG ring 1 response density and general health (p < 0.05, R² = 0.41). mfERG latency was weakly correlated with general vision in the better eye in rings 2 and 4 (p < 0.05, R² < 0.2).

CONCLUSION

Functional assessment in mild/moderate AMD is at best, weakly correlated with patient-reported VR-QoL. Despite the growing awareness of the importance of VR-QoL outcomes in improving patient outcomes and satisfaction, surrogate markers of these outcomes remain elusive, and testing of VR-QoL in regular clinical settings remains difficult.

Evaluation of retinal function improvement in neovascular age-related macular degeneration after intravitreal aflibercept injections with the use of the assessment of retinal sensitivity: The use of the assessment of retinal sensitivity in anti-VEGF treatment - a STROBE-compliant observational study

This study compares 2 methods of macular function evaluation: the microperimetric examination (mean central retinal sensitivity and fixation stability) and the distance best-corrected visual acuity (BCVA) examination, which is the most frequently used method of assessing macular function in patients with newly diagnosed wet age-related macular degeneration (AMD) who have been treated with anti-vascular endothelial growth factor (VEGF) drug (aflibercept).Prospective analysis was conducted on 44 eyes of 44 patients treated with intravitreal injection of anti-VEGF (aflibercept) because of newly diagnosed neovascular AMD. According to the research protocol, all patients had a 6-month follow-up. The response to treatment was monitored functionallybyMP-1 microperimetry, fixation, and distance BCVA assessment after injection. Improvement of retinal sensitivity and BCVA was found under aflibercept treatment. There was statistically significant improvement in retinal sensitivity in the MP-1 study 3 and 6 months from the beginning of anti-VEGF therapy. Moreover, a significant improvement in retinal sensitivity between 3 and 6 months of observation was demonstrated. At the same time, up to 3 months from the beginning of treatment, BCVA improved significantly compared to the baseline value. In the 6th month of the study BCVA remained stable without further significant improvement.Microperimetric examination with medium sensitivity and fixation stability assessment is a very valuable test determining the retinal function. It is clear that examining the macular morphology itself in modern diagnostics is not enough to assess retinal function. Microperimetry technique is a valuable tool for functional long-term evaluation of retinal function (also for a period of more than 3 months).