Myopia is a type of refractive error in which the point of focus is in front of the retina because the cornea is too steeply curved, the axial length of the eye is too long, or both. Distant objects are blurred, but near objects can be seen clearly. Myopic refractive errors in children frequently increase until the child stops growing.
The following symptoms can point to myopia:
- Blurred or distorted vision
- Eyestrain or discomfort
- Difficulty with night vision
In the normally refracted (emmetropic) eye, entering light rays are focused on the retina by the cornea and the lens, creating a sharp image that is transmitted to the brain. During accommodation, the ciliary muscles adjust lens shape to properly focus images. Myopia usually occurs when the axial length is too long due to abnormal shape of the eyeball. Instead of being focused precisely on the retina, light is focused in front of the retina, resulting in a blurry appearance for distant objects. Moreover, myopia may be due to the fact that the cornea is curved too steeply.
The goal of treatment is to compensate for the inability of your eyes to focus on remote objects. Treatment options include wearing corrective eyeglasses or contact lenses, as well as undergoing refractive surgery.
Refractive surgery alters the curvature of the cornea to focus light more precisely on the retina. The goal of refractive surgery is to decrease dependence on eyeglasses or contact lenses.
The two most common refractive surgery procedures are femtosecond laser-assisted in situ keratomileusis (Femto-LASIK) and Small Incision Lenticule Extraction (SMILE).
In Femto-LASIK, a surgeon separates a small flap of tissue from the cornea, using a femtosecond laser. The new profile of the cornea is created with a high-precision excimer laser so that light rays will be focused exactly on the retina. After changing the cornea surface, a flap of corneal tissue, which was separated in the first stage, is turned back. The flap is replaced without suturing. Because surface epithelium is not disrupted centrally, vision returns rapidly. Most people notice a significant improvement the next day.
In some cases, photorefractive keratectomy (PRK) is performed to correct myopia. In PRK, the corneal epithelium is removed and then the excimer laser is used to sculpt the anterior curvature of the corneal stromal bed. The epithelium typically takes 3 to 4 days to regenerate. PRK may be more suitable for patients with thin corneas or anterior basement membrane dystrophy.