Hello, in my opinion, you'd better not trust the optometrist can diagnose cataracts, which at least not precise. Though optometrists have some practice, some skills and some experiences to diagnose some eye problems, but most of them are just common eye problems and not difficult to treat. You'd better go to hospital and have some professional check. Just for sure.
Usually cataract refers to the opacity of crystal lens in eyes, which might be a little obvious. Sometimes we can tell whether a person have cataract or not depending on what their eyes look like. Eyes suffering from cataract usually are dull and cloudy. If the cataract is located on the dark colored part, then it is much more obvious. So it is not surprised that an optometrist can tell you have cataract. But instead of take his advice, I think you should go to visit your ophthalmologist to have an examination and get proper treatment. After all, cataract is the leading cause of blindness which can't be ignored. Don't use hands or unclean towel to rub your eyes. Take frequent breaks to relax eyes and muscles and change the vision focus every 1-2hours. Eye exercises are good for eye health. Arrange a healthy diet with food rich in protein, vitamin A, vitamin B, vitamin C and vitamin E. More fish as food could effectively slow down the development. Quit smoking which is very bad for eyes and overall health.
Usually the unclear things on the eye balls will be suspended as the cataracts. The optometrist may give you the suggestion if you have such symptom. However, you need to go to the professional hospital to check whether you get the cataracts. If so, you need to take the medical or other treatments as soon as possible. Then you will get recovery soon and get healthy eyes.