Retinal detachment is separation of the retina from the underlying layers that line the inner wall of the eye. Through the retinal tear, liquid from the vitreous may pass through the tear, and detach the retina. As the fluid accumulates, more and more of the retina detach. Detached retina loses its function; hence the person with retinal detachment loses vision suddenly or gradually.

The retina is a thin sheet of light sensitive nerve tissue lining the inner aspect of the eye. The light that enters the eye passes through the cornea and lens and is focused on the retina. It is this layer of the eye that turns into light into the visual signal transmitted to the brain, allowing one to see. If the retina is damaged, spectacles alone cannot improve one's vision.

LASIK combines the precision of the excimer laser that is used in PRK surgeries with the flap technique that characterizes ALK. Firstly, removal of the corneal surface tissue is not necessary and therefore, postoperative pain is substantially reduced compared to PRK. Secondly, postoperative visual acuity is restored within a few days rather than weeks. Finally, there is less corneal scarring in the long-term and greater stability of the correction.