Are investigations for treatment of Glaucoma covered under Medical Insurance?

There is a confusion among the medical fraternity whether the investigations for treatment of Glaucoma will be covered under Medical Insurance or not. In my opinion as an Insurance Consultant, since Glaucoma is such a disease requiring periodic investigations to ascertain eye pressure,visibility etc. these should must be allowed as treatment under medical insurance and claims should be entertained accordingly, provided this is not pre-existing one and was diagnosed only after taking the policy after a year.