An eye that has no refractive error when viewing distant objects is said to have emmetropia or be emmetropic meaning the eye is in a state in which it can focus parallel rays of light (light from distant objects) on the retina, without using any accommodation. A distant object in this case is defined as an object 6 meters or further away from the eye. This proves to be an evolutionary advantage by automatically focusing the eye on objects in the distance because it allows an individual to be alert in, say, a prey-predator situation.
Glasses: this is the simplest and most popular way of correcting refractive errors
Contact lens:this option is cosmetically much better though the maintenance and cleaning of contact lenses may be cumbersome.
There is also a slight risk of infection to the cornea, if the contact lenses are not cleaned properly before use.
Refractive surgeries:these are increasingly becoming popular with the advent of more predictable laser treatments.
- Changing the curvature of the cornea: this is the most popular mode of refractive surgery.
- Removing the natural lens and replacing it with an artificial lens of adequate power: it is similar to a routine phacoemulsification surgery, except that it is done in a clear lens and not a lens with cataract. As it is an invasive procedure and it also increases the chances of retinal detachment in eyes with high myopia, it is not recommended nowadays.
- Putting an additional artificial lens within the eye on top of the existing natural lens: this technique is still not very popular as it is also invasive and may increase the chances of cataract formation.