Subjects were 39 patients with ERM (23 women; mean age, 64.1 ± 8.4 years; stage 1, 11 eyes; stage 2, 14 eyes; stage 3, 14 eyes; by Nakajima classification
16 ), 22 patients with M-hole (10 women; mean age, 63.1 ± 12.1 years; stage 1, 8 eyes; stage 2, 4 eyes; stage 3, 10 eyes; by Gass classification
17 ), 19 patients with AMD (3 women; mean age, 67.6 ± 7.8 years; dry type, 6 eyes; wet type, 13 eyes), and 51 healthy subjects (29 women; mean age, 68.0 ± 8.7 years). Their visual acuity (VA, logMAR) ranged from −0.1 to 0.52 in ERM, 0 to 1.3 in M-hole, 0 to 0.7 in AMD, and 0 in healthy subjects. All subjects were first tested by Amsler's Chart and had to be verified to have metamorphopsia. They also underwent a set of ophthalmic examinations including best-corrected visual acuity testing, slit-lamp biomicroscopy, applanation tonometry, dilated funduscopy, fundus photography, scanning laser ophthalmoscopy (SLO, Rodenstock, Germany), optical coherence tomography (Stratus OCT; Carl Zeiss Meditec), M-CHARTS test, and PHP test. Only the patients with AMD were also examined by fluorescein angiography (60 UVi fundus camera; Canon Inc., Tokyo, Japan). After all these clinical tests, the subjects completed the metamorphopsia questionnaire. Inclusion criteria for the subjects were as follows: pupil diameter of >3.0 mm, intraocular pressure of <21 mm Hg, refractive errors within the ranges of −6.0 D to + 3.0 D (spherical) and ± 3.0 D (cylindrical), clear optical media, and no systemic diseases that were likely to affect visual function. Informed consent was obtained from the subjects. All experiments were performed in accordance with the Declaration of Helsinki for research involving human subjects.