Forty-seven eyes of 47 normal subjects (29 women, mean age, 56.4 years; range, 23–78) and 51 eyes of 51 patients with ERM (31 women, mean age, 64.3 years; range, 44–80) were studied. Each subject underwent a complete ophthalmic examination, which included best corrected visual acuity, slit lamp biomicroscopy, applanation tonometry, dilated funduscopy, fundus photography and scanning laser ophthalmoscopy (SLO, Rodenstock). The inclusion criteria for normal subjects were as follows: corrected visual acuity of more than 1.0, pupil diameter of more than 3.0 mm, intraocular pressure of less than 21 mm Hg, no ocular and systemic diseases that were likely to affect their visual functions. One randomly selected eye was examined. The inclusion criteria for ERM patients were as follows: corrected visual acuity of more than 0.1, pupil diameter of more than 3.0 mm, intraocular pressure of less than 21 mm Hg, and no systemic diseases that were likely to affect their visual functions. If ERMs were observed in both eyes, one randomly selected eye was examined. Informed consent was obtained from all normal subjects and ERM patients. All experiments were performed in accordance with the Declaration of Helsinki for research involving human subjects.