The cornea is the clear, transparent, protective outer layer of the eye that serves as the barrier to foreign materials and pathogens. Furthermore, the cornea is important for vision as it focuses the light rays to fall on the retina. If the cornea gets damaged by disease, trauma, or infections, it can result in corneal scarring.
A corneal scar is either an opacity or irregularity that reduces the ability of the cornea to properly focus the light rays necessary to visualize any object. If the scar is at the outer edges of the cornea, it may not affect the vision. However, if the scar lies on the central cornea, it can compromise the vision significantly.
The most common causes leading to corneal scarring are:
- Injuries or trauma to the eyes: Abrasions, mishandling of contact lenses, or any other trauma to eyes.
- Infections: Any bacterial, viral, fungal, or parasitic infection that penetrates the Bowman’s or stromal layer can lead to scar formation.
- Corneal ulcer: If a corneal ulcer penetrates the Bowman’s or stromal layer, it can cause scarring.
- Corneal/Ocular diseases such as keratitis, keratoconus, etc.
- Corneal dystrophy: Corneal dystrophies that cause recurrent corneal erosions can lead to corneal scarring.
Generally, corneal scars are diagnosed during a routine eye exam. A corneal scar appears as white opacity or irregularity in the cornea that is normally clear and transparent. Some corneal scars can be visible to the naked eye. However, some corneal scars can be very difficult to detect.
Scars that can change the shape of the cornea, making the surface more irregular, may not be detectable during a routine eye exam with the ophthalmologist. A corneal topography may be useful in the diagnosis of such cases. Corneal topography is a topographical map of the cornea that shows if there are any changes on the surface of the cornea, whether it is misshapen or irregular.
Many milder forms of corneal scars heal spontaneously without the need for any treatment. Serious cases with impaired vision need to be evaluated by an ophthalmologist to improve and restore vision. The treatment options available for the removal of corneal scars include:
- Glasses: Glasses can be used for relatively milder cases of corneal scarring.
- Scleral contact lenses: For moderate cases of corneal scarring that do not improve with just glasses, scleral contact lenses can be used to improve vision.
- Laser Phototherapeutic Keratectomy (PTK): An ophthalmologist can also suggest a laser phototherapeutic keratectomy that uses an excimer laser to remodel superficial corneal scars.
- Corneal transplant: In severe cases of corneal scarring, scleral lenses or laser PTK may not improve the vision impairment. Hence, an ophthalmologist may opt for a corneal transplant in which all the diseased part of the cornea gets replaced with healthy donor corneal tissues. The most advanced treatment procedures, such as DALK (Deep Anterior Lamellar Keratoplasty), can be a relatively better treatment option as it preserves the innermost corneal layer and has a faster recovery.