Corneal Scarring

A cornea scar is an irregularity or opacity in the cornea that can restrict the cornea from focusing light adequately. These scars can be caused by deep scratches, improper use of contact lenses, burns, lacerations, and certain diseases and infections. You should note that not all scars affect vision. If the scar is present on the outer edges of the cornea, it may not affect your vision at all. However, if the scar is in the central cornea, over the pupil, it may lead to significant vision loss.

Corneal scarring can be caused due to improper use of contact lenses, trauma, or eye conditions. The causes include:-

1. Improper use of contact lenses: This is one of the most common causes of corneal scarring. It can include improper cleaning and replacement schedules, inappropriate hand hygiene, and sleeping while wearing contact lenses. These factors can increase the risk of infections and corneal ulcers, resulting in subsequent scars. 
2. Corneal abrasion or eye injury: Most corneal abrasions (scratches) affect only the cornea’s outer layer. Minor injuries to the cornea can be caused by foreign objects like a tree branch, pencil, pen, or contact lenses. More serious injuries that leave a scar on the cornea include sharp materials or a ball directly hitting the eye. 
3. Keratitis: It is a medical term for corneal infections. If left untreated, keratitis can lead to permanent corneal damage such as scarring. Keratitis may include:-
   1. Herpes zoster (shingles): It is a painful, blistering rash caused by the same virus that causes chickenpox. Shingles that develop on the neck, face, or head can also affect the cornea. 
   2. Ocular herpes: It is caused by the herpes simplex virus that causes oral and genital herpes. It develops on the eyelid or surface of the eye, leading to corneal inflammation. 
4. Corneal degenerations: It involves the structural problems of the cornea developed over time. One such degeneration is keratoconus, which results in thinned, irregular-shaped corneas. This irregularity causes blurry vision and results in cornea swelling and scarring. 
5. Epithelial basement membrane dystrophy: The condition causes abnormal growth on the epithelium (outer layer of your eye). This growth can create scar tissue and distort your vision.

The symptoms of corneal scarring include:-

1. Blurred vision
2. Excessive pain
3. Sensitivity to light
4. A burning sensation in the eye
5. Eyelid swelling
6. Feeling like something is there in the eye
7. Red eyes
8. Excessive tearing

Your doctor may conduct some tests to diagnose corneal scarring, which include:-

1. Eye Exam: During the eye exam, the doctor may use magnifying tools, such as a slit lamp or ophthalmoscope, to view your eye better. They may look for a white opacity in a normally clear cornea. 
2. Fluorescein Eye Stain: It is a test to detect corneal injuries where the doctor uses dyed eye drops and blue light to look at the layers of the cornea. 
3. Corneal Topography: Scars that change the shape of the cornea cannot be diagnosed in a regular eye exam. In such cases, the doctor uses a corneal topography that creates a three-dimensional map of the cornea’s surface curvature. 
4. Visual Acuity Test: A test used to determine how well you can read letters and symbols from a specific distance. 

The corneal scarring treatment includes:-

Glasses or contact lenses: If you have milder scars, glasses alone can be effective in improving your vision. If glasses are insufficient, your doctor may customise special contact lenses, such as rigid gas permeable and scleral lenses, to provide the best vision possible. 

Eye drops: You may have to take antibiotic or steroid eye drops to heal the scar on your cornea. 

If the treatment is delayed, corneal scarring can lead to:-

1. Low vision
2. Blindness
3. Amblyopia (lazy eye)
4. Strabismus (crossed eyes)