Removal of one intracorneal ring segment could improve visual acuity in myopic patients

HONG KONG — The removal of one intracorneal ring segment in myopic keratoconic patients who have had poor results with double ring implantation can improve visual outcomes, a surgeon said.

Brian Boxer Wachler, MD, described outcomes in 13 eyes of 10 myopic patients who underwent explantation of their upper Intacs segment (Addition Technology). The patients' average visual acuity before the upper segment was removed was 20/50. After the segment was removed, the average visual acuity improved to 20/30, Dr. Boxer-Wachler told attendees of the World Ophthalmology Congress.

Improvement in visual acuity was seen in all 13 eyes. Seven eyes (54%) gained one line, four eyes (32%) gained two lines, one eye (7%) gained three lines, and one eye (7%) gained four lines.

This apparent improvement in visual acuity is "counterintuitive and hard to explain," Dr. Boxer-Wachler said. However, corneal topography helps demonstrate why two segments will not bring about the desired effect in the flattest area of the cornea. "When you place two segments, Intacs will always flatten. That is what they do - that's their goal in life," he said. "But why do you want to make a flat area even flatter? You really don't. If anything, you want to make the [flatter zone] actually steeper."

Dr. Boxer-Wachler said explantation of the upper segment is not technically difficult to accomplish.

"You can even just make a little cut down over the tip of Intacs, and you don't have to go over the incision. You don't have to worry about going back over the original channel," he said.

Further, removal of the upper segment is as beneficial as if only one segment had been implanted at the outset, in that it will allow steepening to occur in areas that are being flattened by the segment.

Dr. Boxer-Wachler also said that surgeons can "make huge improvements in astigmatism" by placing a few conductive keratoplasty (CK, Refractec) spots on the cornea.

"If you see someone with double segments, look at the topography, look at the location of the segments and see if it would make sense to explant the ones from the flat area of the cornea," he said.