1. Department of Ophthalmology , Rīga Stradiņš University , 16 Dzirciema Str., Rīga, LV-1007 , Latvia
2. Department of Ophthalmology , Pauls Stradiņš Clinical University Hospital , 13 Pilsoņu Str., Rīga, LV-1002 , Latvia
3. Faculty of Medicine , University of Latvia , 19 Raiņa Blvd., Rīga, LV-1586 , Latvia