Any injury to the body, including surgery, induces a healing response. And this healing response inevitably includes inflammation.
Bear in mind, inflammation is not the same as infection, as many people may mistakenly believe. Inflammation is a series of changes in the body that includes dilation of blood vessels, increased leakiness of blood vessels, recruitment of white blood cells to the area, etc.
The whole aim of inflammation is to fight any germs present and to facilitate the healing of the injured area. But inflammation is also associated with pain, tenderness, some degree of swelling and so on.
It is also possible that sometimes inflammation can get more severe than is necessary for healing to occur. This can lead to so called 'collateral damage', where undesirable things happen that are unconnected to the healing process itself. For example, inflammation itself can cause corneal swelling and haziness, or retinal swelling (cystoid macular oedema).
This is why steroid drops are given after many, if not most, eye operations including cataract surgery.
So if you don't use the steroid drops or stop too soon, there is the risk of the eye turning red and sore, and possibly the vision getting blurry also. It's best to follow your doctor's advice on medication use and frequency, and always ask if you are not sure about anything.
