Abstract
PurposeMicroperimetry (MP) allows for measurement of retinal sensitivity at precise locations and is now commonly employed as a clinical trial endpoint. Test–retest reliability is important when evaluating treatment effects in patients with geographic atrophy (GA). This study aimed to determine the test–retest variability of MP in patients with moderate to severe GA using the MAIA MP device.MethodsIn this prospective study, patients with a confirmed diagnosis of foveal-involving GA were enrolled. Participants performed three MP assessments of a selected eye over two visits with the Macular Integrity Assessment (MAIA) 2 instrument (Centervue, Padova, Italy) utilizing a wide 30° grid, consisting of 93 stimuli (Goldmann III) using a 4-2 representation strategy, encompassing the entire area of GA and beyond. Mean retinal sensitivity (MS) was expressed as an average threshold value (dB) for the entire field tested. Coefficients of Repeatability at a 95% level (CoR95) were calculated for Point Wise Sensitivity (PWS). Fixation stability (FS) was assessed by evaluating the area of an elliptical representation encompassing 95% of the cloud of fixation points (CFP) dataset generated by the MAIA MP, known as the bivariate contour ellipse area (BCEA).ResultsA total of 8 subjects were enrolled (21 tests), with six subjects completing 3 MP assessments. BCVA in these patients ranged from 20/100 to 20/800. The mean area of GA was 18.7 ± 12.3 mm2. The average time to complete one MP assessment was 13 min 9 s and mean BCEA@95% was 38.5 ± 19.3°2. The MS was 14.3 ± 4.5 dB. No significant increase in MS was noted between testing pairs 1&2 and 2&3. The preferred retinal locus was maintained in the same quadrant on successive tests. The mean CoR95 for PWS were similar for testing pairs 1&2 (± 3.50 dB) and 2&3 (± 3.40).ConclusionMicroperimetry using a wide grid can be reliably performed in a reasonable amount of time in patients with moderate and severe vision loss secondary to GA. There was no learning effect seen between sequential assessments when analyzing MS or PWS. A change of approximately 4 dB in PWS provides a threshold for considering a true change in this patient cohort.
Highlights
Microperimetry (MP) is a several-decades old technology designed to test retinal sensitivity at different points in the macula
Changes in retinal function on MP have been shown to extend beyond the borders of GA, and changes in scotomatous points associated with GA growth, suggesting that MP may hold potential in better assessing the extent of visual loss and predicting progression in patients with geographic atrophy (GA) [3]
There was no correlation found between GA size and any MP performance metric or between baseline best corrected visual acuity (BCVA) and MP performance
Summary
Microperimetry (MP) is a several-decades old technology designed to test retinal sensitivity at different points in the macula. Microperimetry (MP) has gained more widespread adoption as a means of Alibhai et al Int J Retin Vitr (2020) 6:16 functional retinal assessment. Microperimetry is routinely employed in clinical trials as an endpoint; in the phase 3 clinical trial of lampalizumab, sensitivity assessed by microperimetry was used as a secondary endpoint in a subset of patients [2]. Changes in retinal function on MP have been shown to extend beyond the borders of GA, and changes in scotomatous points associated with GA growth, suggesting that MP may hold potential in better assessing the extent of visual loss and predicting progression in patients with geographic atrophy (GA) [3]
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