1. From the Department of Ophthalmology, Glostrup Hospital, University of Copenhagen, Copenhagen, Denmark;
2. Danish Epidemiology Science Center, Institute of Preventive Medicine, Copenhagen University Hospital, Copenhagen, Denmark;
3. Danish Twin Registry, University of Southern Denmark, Odense, Denmark; and
4. From the Department of Ophthalmology, Glostrup Hospital, University of Copenhagen, Copenhagen, Denmark;4Kennedy Institute, National Eye Clinic, Hellerup, Denmark.