Hi, Let me first talk somethilg about cataract, diabetes & glaucoma and after that I will list the precaution - ***(A)CATARACT - is basically crystal of excess sugar ( glucose is converted in to sorbitol and sorbitol being whitish is color obscure the passing of light through the lens of eye ) Hence due to whitish substance that is present in the transparent lense of eye is know as CATARACT . The surgery of the cataract is the way of pulling out the crystalloid substance out of the lens allowing the passage of light again and vision is returned. ***(B) DIABETES: - as we all know is problem of increase glucose/sugar in blood, so person having diabetes will have higher chances of having cataract, but effect of having high glucose is not restricted to the LENS of eye but it also affect the RETINA of eye ( curtain of eye that senses the light rays and help brain to form an image, in turn helping us to see in general terms). The high glucose have an adverse effects on the retina making it bit patchy due to prolonged high level, diabetes also effects the blood vessels in eye leading to less availability of blood to retina hence may result in some retinal vision damage. ***(C) GLAUCOMA: - its high pressure of fluid in the eyes due to various reason , ( Eyes will feel pressure with nausea , severe headache and blurry vision, this is an emergency condition if such thing happens please grab an emergency services help. PRECAUTIONS: - 1) Make sure you have a regular check up of back side of eye that is for changes in RETINA, ONCE every YEAR. 2) In case of tunnel vision/ feeling pressure/ pain in eye contact emergency services 3) Please take diabetes & glaucoma medication regularly as prescribe. 4) Eye pressure / glaucoma needs to be checked every 4 months. 5) Exercise will help lowering the sugar hence keep diabetes in control, 6) Please avoid intense sunlight/ wear protective gear like sunglasses. Hope it helps.