Common eye operations.

Cataract
When the lens inside the eye becomes less than clear it can be removed and replaced by a plastic lens to restore vision.
Diabetic surgery
In diabetes great damage can be caused to the retina by scarring from deseased blood vessels. Lasers can be used to stop this happening.
Squint
Where the muscles around the eyes are altered in length or position to make both eyes point in the same direction.
Refractive
Where surgery is used to change the refractive power of the eye. Ideally the proceedure should not damage the eye in any way and must not leave the vision worse in any way than beforehand.