A total of 5000 patients of glaucoma are identified and surveyed by patient interviews regarding family history of glaucoma. Such a study design is called-

Case series repo: A case series repo is a descriptive study where in more than one patients having a paicular disease are studied. No cause related analysis or hypothesis testing is involved. Case control study: Backward looking/ retrospective study in which multiple risk factors are studied together. Odd's ratio can be calculated. Coho study: Forward / prospective study in which multiple outcomes can be studied together. Incidence & relative risk can be calculated.