Lamellar or penetrating keratoplasty: last resort for ectasia after LASIK?

When other possible treatments for ectasia fail, lamellar keratoplasty (LK) or penetrating keratoplasty (PK) may be the last resort for these patients, said William Culbertson, MD.

"Indications of this treatment are the inability to see adequately with glasses or rigid gas-permeable contact lenses or when other treatments fail, including collagen cross-linking," Dr. Culbertson said. "The goal is to make the patient visually functional again with either glasses or contact lenses."

The progression of treatments to follow, according to Dr. Culbertson, is first to confirm the progression of the ectasia; collagen cross-linking can be used in cases in which progression is occurring. Corneal implants (Intacs, Addition Technology), surface ablation, or both also can be considered.

In patients who require keratoplasty the routine preoperative evaluation includes documentation of the patient's vocation and avocation and determination of the patient's expectations and the ability to wear a contact lens postoperatively as well as the cause of the ectasia if possible, according to Dr. Culbertson. He is from Bascom Palmer Eye Institute, Miami.

He also noted that the area of corneal steepening and the thickness of the residual stromal bed should be determined by slit-lamp examination or scanning technology.

"These factors are important for determining which keratoplasty technique to use," he said.

PK can be performed if the patient requires 20/20 vision and the period of visual rehabilitation is not critical; rehabilitation can take from 6 to 24 months. PK can also be performed in patients with a thin central cornea and a thick peripheral cornea in those patients not vulnerable to trauma. LK can be performed in patients who can function with 20/30 vision postoperatively and rapid rehabilitation time is important, Dr. Culbertson explained.

The final visual outcome with PK is unpredictable and high astigmatism often develops. The procedure carries a 5% risk of graft rejection. However, the final visual acuity can be good, but ranges from 20/20 to 20/40. With LK, despite the rapid visual rehabilitation, the increase in the refraction is minimal, there is irregular astigmatism and interface haze. There is no graft rejection with this procedure, but the final visual acuities can range from 20/30 and 20/25 at best.