Comparison of Quantitative Metamorphopsia- Measurements in Patients With mCNV

The myopic CNV is a neovascularization starting from the choroid and growing into the space between choroid and retina, based on pathological myopia (severe myopia). Choroidal neovascularization secondary to pathological myopia (mCNV) is the most common cause of severe visual impairment in myopic patients younger than 50 years old.1 As untreated subretinal fibrovascular membranes cause rapid damage to the photoreceptors, timely treatment is required in view of poor spontaneous prognosis.1

Metamorphopsia is the first functional impairment which occurs in mCNV - visual acuity loss and scotoma follow later. The Amsler Grid, a qualitative paper test developed the swiss ophthalmologist Marc Amsler (1891 - 1968), is a square-shaped grid used to detect or monitor metamorphopsia or scotoma involving the central visual field in various disorders of the macula and optic nerve head11.

Myopic CNV patients use the Amsler Grid as a home monitoring device for qualitative detection of metamorphopsia by checking the grid regularly11. Due to subretinal scarring in mCNV interpretation is often difficult and early changes cannot be detected and quantified. Until now there are no quantitative measurements for mCNV monitoring in clinical use.

Recently, two devices to detect and monitor metamorphopsia using smart phones and PCs, respectively, have been developed for use in choroidal neovascularization in age-related macular degeneration.5,6

• Alleye® Test Alleye® Test is a mobile medical software application indicated for the detection and characterization of metamorphopsia. For the mean Alleye score (±standard deviation (SD) deviations of dots from an ideal line are calculated for each eye.5
• AMD-A Metamorphopsia Detector® Is based on the Amsler grid. The software uses the concept of a negative image: a distorted image can be straightened by moving the mouse. Degree and dimension of distorted lines or scotoma are transformed into indices.6

This study was designed to find out whether these metamorphopsia applications are suitable for patients with mCNV and to find out if mCNV patients can benefit for a quicker detecting of the metamorphopsia.

Therefore, the aim of this study is to detect metamorphopsia and verify correlations of different indexes with disease activity or not, measured in Optical Cohorence Tomography (OCT), best corrected visual Acuity (BCVA), Vision related quality of life questionnaire (NEI-VFY-25) and quantify severity of metamophopsia.

Inclusion criteria

• diagnosis of mCNV involving the juxtafoveal or/and foveal region
• BCVA >0.1 (20/200, Snellen)
• ability to follow the study procedures
• given written consent to participation
• >18 years

Exclusion criteria

• history of vitreoretinal surgery (including membrane peeling and retinal detachment surgery) to the study eye
• presence of macula foramen or epiretinal membrane with significant distortion of retinal architecture
• history of any side effects to Tropicamide eye drops