1. Department of Ophthalmology and Visual Science, Chiba University Graduate School of Medicine, 1-8-1, Inohana, Chuo-ku, Chiba 260-8670, Japan
2. Biostatistics Section, Clinical Research Center, Chiba University Hospital, 1-8-1, Inohana, Chuo-ku, Chiba 260-8670, Japan
3. National Hospital Organization Chiba Medical Center, 4-1-2, Tsubakimori, Chuo-ku, Chiba 260-8606, Japan
4. Department of Ophthalmology, International University of Health and Welfare School of Medicine, 4-3, Kozunomori, Narita 286-8686, Japan
5. Chiba Rosai Hospital, 2-16, Tatsumidaihigashi, Ichihara 290-0003, Japan