SLO-Microperimetry in Wet Age-Related Macular Degeneration During Anti-VEGF Therapy

A Tablet-Based Retinal Function Test in Neovascular Age-Related Macular Degeneration Eyes and At-Risk Fellow Eye

Purpose

To determine the feasibility of a tablet-based application to detect changes in retinal sensitivity and correlations with underlying pathology in neovascular age-related macular degeneration (nAMD) eyes undergoing treatment and in at-risk fellow eyes.

Method

Participants with nAMD in at least one eye were recruited, examined, and imaged using spectral-domain optical coherence tomography (SD-OCT). Retinal sensitivity was measured within the central 5° at 12 locations using a customized test delivered on an iPad. Test points were superimposed on SD-OCT locations to investigate structure/function relationships.

Results

Included in the study were 53 nAMD eyes and 21 at-risk fellow eyes. In nAMD eyes, the mean retinal sensitivity was 24.1 ± 1.8 dB with reduced retinal sensitivity associated with the presence of atrophy (P < 0.01), retinal pigment epithelium (RPE) disruption (P < 0.01), and absent ellipsoid zone (EZ) (P < 0.01), but not with the presence of subretinal fluid (P = 0.94) nor intraretinal fluid (P = 0.52). In at-risk eyes, the average retinal sensitivity was 28.8 ± 0.6 dB, with reduced sensitivity significantly associated with the presence of drusen, atrophy, RPE disruption, and absent EZ (P < 0.01).

Conclusion

The tablet-based test of retinal sensitivity was able to be performed by an elderly cohort with nAMD. The ability to correlate differences in sensitivity with pathology is encouraging when considering using the tablet devices as a home monitoring tool with remote surveillance. Dual pathology often present with retinal fluid confounded our ability to correlate fluid with sensitivity.

Translational Relevance

These findings highlight the potential of tablet-based devices in performing visual function measures as a home monitoring tool with remote surveillance for the earlier detection of nAMD.

Mesopic and Dark-Adapted Two-Color Fundus-Controlled Perimetry in Choroidal Neovascularization Secondary to Age-Related Macular Degeneration

Purpose

To determine the retest variability of mesopic and two-color dark-adapted (DA) fundus-controlled perimetry (FCP), to evaluate the predictive value of patient reliability indices, and to analyze the extent of impairment of rod- and cone function in neovascular age-related macular degeneration (nAMD).

Methods

A total of 50 eyes of 50 patients with nAMD (mean age, 76.1 years) and 70 eyes of 70 age-similar normal subjects underwent multimodal imaging as well as mesopic and DA two-color perimetry using the S-MAIA device. A subset of patients (n = 28) underwent duplicate testing for retest reliability assessment. Mixed models were used for analysis of the hierarchical data.

Results

In eyes with nAMD, the coefficient of repeatability was (mean ± standard deviation [SD]) 5.99 ± 1.55 dB for mesopic, 6.14 ± 2.19 dB for DA cyan, and 6.06 ± 1.09 dB for DA red testing. “Patient reliability indices” explained 55%, 54.2%, and 64.2% of the variance in retest variability. The mean sensitivity loss was greater for DA cyan compared to DA red testing (cyan-red differences [mean ± SD] −2.63 ± 3.87 dB, P < 0.001).

Conclusions

The relatively greater degree of DA cyan versus DA red sensitivity loss indicates preferential rod vulnerability in nAMD, and qualifies rod function-based outcomes measures as potential sensitive and early markers of treatment response in nAMD.

Translational Relevance

The S-MAIA allows reliable testing of mesopic, DA cyan, and DA red sensitivity in patients with nAMD. Patient reliability indices may serve as eligibility criteria for clinical trials to identify patients with adequate retest reliability.

The use of microperimetry in assessing visual function in age-related macular degeneration

Microperimetry is a novel technique for assessing visual function that appears particularly suitable for age-related macular degeneration (AMD). Compared with standard automated perimetry, microperimetry offers several unique features. It simultaneously images the fundus, incorporates an eye-tracking system to correct the stimulus location for fixation loss, and identifies any preferred retinal loci. We identified 52 articles that met the inclusion criteria for a systematic review of microperimetry in the assessment of visual function in AMD. We discuss microperimetry and AMD in relation to disease severity, structural imaging outcomes, other measures of visual function, and evaluation of the efficacy of surgical and/or medical therapies in clinical trials. The evidence for the use of microperimetry in the functional assessment of AMD is encouraging. Disruptions of the ellipsoid zone band and retinal pigment epithelium are clearly associated with reduced differential light sensitivity despite the maintenance of good visual acuity. Reduced differential light sensitivity is also associated with outer segment thinning and retinal pigment epithelium thickening in early AMD and with both a thickening and a thinning of the whole retina in choroidal neovascularization. Microperimetry, however, lacks the robust diffuse and focal loss age-corrected probability analyses associated with standard automated perimetry, and the technique is currently limited by this omission.

Microperimetry in age: related macular degeneration

Age-related macular degeneration (AMD) is one of the major causes of visual loss and legal blindness in people over 55. Visual function tests are the cornerstone of visual function investigation and any therapeutic approach to AMD implies, as primary endpoint, the maintenance or improvement of visual function. The progression of visual impairment and the quantification of final residual visual function are currently determined by means of visual acuity quantification. The quantification of high-contrast visual acuity though has many drawbacks and cannot be considered a complete functional examination. Microperimetry is a non-invasive method used to analyse fixation and central visual field defects in a topographic related manner. The introduction of mesopic and more recently scotopic microperimetry, in research and clinical practice of macular disorders, now allows us to better investigate macular function as it strictly relates to macular morphology. We therefore can monitor the functional natural history and quantify the beneficial or detrimental effects of different therapies. The application of microperimetry in clinical studies has provided interesting diagnostic and prognostic information on functional macular changes in AMD patients. The present review brings new updates on the correlation between macular changes, mainly described with optical coherence tomography, and microperimetry changes in patients with AMD.