Prospective Study Comparing Quantitative Self-Monitoring Metamorphopsia Measurement Tools in Myopic Choroidal Neovascularization (mCNV)

PURPOSE: To assess the ability of two self-monitoring digital devices to detect metamorphopsia in myopic choroidal neovascularization (mCNV) and compare their usability. PATIENTS AND METHODS: This was a 12-month prospective observational study at a tertiary care eye hospital, Switzerland. Twenty-three Caucasian patients with mCNV were recruited, 21 eyes were analyzed. Primary and secondary outcome measures: Primary outcome measures were the metamorphopsia index scores as assessed by the two self-monitoring digital devices (Alleye App and AMD – A-Metamorphopsia-Detector software) at baseline, at 6 and 12 months and individual optional visits in between. Secondary outcome measures included best corrected visual acuity and morphological parameters (including disease activity) as evaluated by spectral-domain optical coherence tomography and fundus autofluorescence imaging. Location of mCNV was graded using the Early Treatment of Diabetic Retinopathy Study grid overlay. A usability questionnaire was administered at 12 months. Bland-Altman plots evaluated the limits of agreement of both devices. Linear regression analysis assessed the correlation between the difference and the average of the two scores. RESULTS: A total of 202 tests were performed. Disease activity of mCNV was observed at least once in 14 eyes. Both scores concordantly detected metamorphopsia exhibiting a displaced scale of measurement yielding a coefficient of determination of 0.99. Concordance rate for pathological scores was 73.3%. Both scores were not significantly different in active and inactive mCNV. Overall, the usability scores were higher for the Alleye App than the AMD – A-Metamorphopsia-Detector software (4.61±0.56 vs 3.31±1.20; p<0.001). In subjects aged >75 years, scores were slightly lower (4.08±0.86 vs 2.97±1.16; p= 0.032). CONCLUSION: Whilst both self-monitoring devices concordantly identified metamorphopsia, they might act as an adjunct to hospital visits, but due to slight reactivations in mCNV and presence of metamorphopsia also in inactive disease the ability of detecting early mCNV activity might be limited.