Six months ago, I was diagnosed with iritis, as well as a tear on my cornea. Now the tear is back, not only on the same spot as previously, but on a new spot as well. What is causing this? More importantly, how can I prevent this from happening again? I have been prescribed Tobradex ointment, but I am still experiencing a significant amount of eye pain, as well as light sensitivity and constant watering.

E.

The condition you seem to be experiencing is called recurrent epithelial erosion syndrome, which usually develops following a scratch or other abrasion to the outer layer of the cornea (epithelium). The scratch generally causes the epithelium to peel away, exposing deeper portions of the cornea. Corneal scratches tend to heal quickly. However, the epithelium that grows back over the injured area may not "stick" as well to the underlying surface as the original epithelium. Hence the name, recurrent epithelial erosion syndrome.

Months to years after a corneal abrasion, it is not uncommon for a person to wake up in the morning with sharp pain in the eye. Shortly afterward, the person may notice the eye is red and sensitive to light. Examination by an ophthalmologist will reveal a corneal abrasion in the area of the previous corneal abrasion. The ophthalmologist will treat this episode with antibiotic drops. Over the next day or so, the cornea will heal. However, this patient is now at risk for a similar event to occur multiple times.

In general, episodes of recurrent epithelial erosion syndrome always begin shortly after a patient wakes up. No one knows exactly why, but the theory is that the eyelid sticks to the corneal epithelium during sleep, and when the eyelid opens, it rips the epithelium.

The prevention of recurrences begins with the use of artificial tears and lubricating ointments at night. In addition, a sterile salt solution called Muro 128 can sometimes help. It is thought Muro 128 helps to dry up any fluid that may exist between the loosed epithelium and the underlying cornea.

If recurrences continue, the next treatment is called stromal puncture. Doctors use a bent sterile needle to make tiny pricks through the surface of the loose epithelium. The epithelium grows down into these little "divots," functioning as anchors to prevent the epithelium from sloughing off. This procedure is about 50-60 percent effective. Another treatment involves the excimer laser. In this procedure, called phototherapeutic keratectomy (PTK), the epithelium is removed with a spatula, and then the laser is used to reshape the deeper cornea. The epithelium then grows back over three days, and often the new epithelium sticks better to the underlying layers of cornea. This technique also has a 50-60 percent success rate, but is generally more expensive than stromal puncture.

To reduce your risk of suffering future episodes of recurrent epithelial erosion syndrome, you should discuss your treatment options with your eye doctor.