Final answer:
The study to determine the link between smoking and glaucoma is a case-control study.
Step-by-step explanation:
The type of observational study that is being conducted to determine the link between smoking and glaucoma is a case-control study. In this study, past records of glaucoma patients are observed and divided into two groups: smokers and non-smokers. The researchers then compare the groups to see if there is an association between smoking and glaucoma.