Cornea and External Disease FAQ's
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1. What is the cornea?
The cornea is the clear, dome-shaped layer on the front of the eye. It consists of 5 layers. It is responsible for most of the eye’s refractive power (focusing light). It needs to remain clear in order to have sharp vision. Scarring or swelling of the cornea limits your vision.
2. What conditions are treated by cornea specialists?
Infections (corneal ulcers), tumors or growths (pterygium, ocular surface neoplasms) corneal foreign body removal, swelling (Fuch’s dystrophy), dry eyes, pterygium, and more, as well as general ophthalmology (cataract surgery).
3. What is a corneal ulcer?
It is an infection of the cornea. Bacteria are the most common cause of corneal ulcers, however, viruses, fungi, and amoeba are other causes. Contact lens use is associated with a higher risk of ulcers, particularly extended wear contacts or sleeping in contacts. They are treated with frequent eye drops, and can lead to reduced vision from scarring.
4. What is map, dot, fingerprint dystrophy (MDF)?
Also known as epithelial basement membrane dystrophy (EBMD) it is a disorder of the surface layer of the cornea. It is present in ~10% of the population. Milder cases can be monitored. Moderate and advanced cases often require treatment if they cause astigmatism, decreased vision, or recurrent erosion (repeated corneal abrasions). This problem may need to be fixed prior to undergoing cataract surgery.
5. What is recurrent erosion?
A scratch on the surface layer of the cornea (epithelium) that results from a prior corneal abrasion, or an underlying disorder of the cornea that makes abrasions more common (map dot fingerprint dystrophy, superficial and stromal corneal dystrophies). This commonly presents upon awakening with pain, foreign body sensation, and sensitivity to light. The cornea swells overnight when the lids are closed. When the eye is opened the eyelid rubs against the weakened and swollen area of the cornea, and can lead to recurrent erosion. It can be treated medically or surgically.
6. What is a superficial keratectomy?
A surgical treatment for MDF and recurrent erosion. The irregular surface layer of the cornea (epithelium) is removed and the underlying area is polished to encourage new healthy cells to grow in place of the previously irregular cells. A contact lens is placed after the surgery and 2 eyedrops are given for healing and comfort. The procedure takes less than 10 minutes. Vision fluctuates for a few days during the healing process.
7. What is Fuch’s dystrophy?
Fuch’s dystrophy is a disorder of the posterior (back layer of the) cornea. The endothelial cells pump fluid out of the cornea and provide it with nutrients. Age naturally lowers the number of endothelial cells a patient has. In Fuch’s dystrophy there is premature death of endothelial cells, which can lead to fluctuating vision, glare, and swelling of the cornea. It normally presents in one’s 40s or 50s, can be inherited, and often worsens after ocular surgeries. Milder cases can be monitored or treated with eye drops and ointment. Advanced cases require corneal transplantation.
8. What are common types of corneal transplantation?
a. Penetrating keratoplasty (full-thickness transplant): this is indicated for keratoconus, or large corneal scars.
b. DSAEK or DMEK (partial replacement of the back layer of the cornea): most cases of Fuch’s dystrophy or swollen corneas can be treated with DSAEK or DMEK. Partial thickness transplants result in a faster visual recovery with less stitches and drops, and a lower risk of transplant rejection.
9. What is a pterygium?
An abnormal growth of tissue (fibrous and vascular) associated with sun exposure. Small pterygium can be monitored. Larger pterygium are removed if they cause astigmatism or approach the visual axis (center of the cornea). A conjunctival graft from the patient’s eye is secured with sutures following removal of the pterygium. This provides the lowest risk of regrowth. Sutures are removed 7-10 days after the procedure, and drops are used for 2 months after surgery. The surgery takes ~45 minutes.
10. What are treatments for dry eyes other than eye drops?
a. Punctal plugs: small clear silicone (permanent) or collagen (temporary dissolving) plugs block the tear drainage system of the eye to increase the moisture on the surface of the eye. Plugs are usually placed in the lower tear drainage system. This is more common than punctal cautery (permanent scarring of the puncta).
b. LipiFlow: FDA approved treatment for dry eyes. 13 minute procedure where the clogged oil glands of the eyelid are heated and expressed. As 86% of dry eye patients have a component of meibomian gland dysfunction (clogged oil glands), this is an effective way of improving dry eye symptoms in many patients.
c. Blephex: an in-office treatment to clean the eyelid margin and eyelashes. It removes bacteria, crusting, and bioflims. It treats eyelid inflammation (blepharitis), including Demodex (mites).
d. Amniotic membrane: a layer of the placenta, it is used in dry or frozen form to treat severe cases of dry eyes, or non-healing abrasions or infections. It is anti-inflammatory and promotes wound healing. The tissue dissolves over 5-7 days.
11. What is herpes keratitis?
Herpes simplex and herpes zoster (Shingles) keratitis can affect any layer of the cornea. Patients with eye involvement may have lesions on their face or the tip of their nose. The infection is treated with oral antiviral pills and sometimes with antiviral and anti-inflammatory (steroid) drops. The incidence of Shingles is going up and can affect patient’s in their 40s and 50s. We recommend the Shingles vaccine (Shingrix) to all eligible patients. Herpes infections can come back after treatment, and require close monitoring.