Corneal tissue addition for keratoconus may improve visual acuity, topography
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Corneal tissue addition appears to improve visual acuity and topography in patients with severe keratoconus, according to a speaker at the virtual American Academy of Ophthalmology annual meeting.
“These are early results of this procedure, but they are encouraging,” Steven A. Greenstein, MD, of Cornea and Laser Eye Institute - CLEI Center for Keratoconus, New Jersey, said.
The procedure, corneal tissue addition for keratoconus (CTAK), uses sterile, preserved, shelf-stable corneal tissue (halo, Lions VisionGift) that is shaped into a crescent with a femtosecond laser (iFS, Johnson & Johnson Vision) and then placed in a channel created by the femtosecond laser in a technique similar to corneal ring placement. The CTAK tissue segment can be customized by width, thickness and length, Greenstein said.
The authors presented data from a prospective clinical trial including seven patients who underwent CTAK, six with keratoconus and one with ectasia after LASIK, with 1-month data for all patients and 6-month data for four patients. At baseline, average maximum keratometry was 82.4 D, and the average thinnest pachymetry was 356 µm.
Overall, uncorrected visual acuity and best corrected visual acuity improved by about four logMAR lines, Greenstein said.
Average UCVA improved from worse than 20/400 in Snellen equivalent to about 20/160 at 1 month after surgery.
“With best spectacle-corrected visual acuity, that improvement was a little better than 20/200 to about 20/70,” Greenstein said.
Improvement in topography depended on whether a full-thickness, about 550 µm, or half-thickness, about 200 µm, graft was placed.
On average, patients’ maximum flattening was about 19 D at 1 month after surgery “and a little bit more” for patients at 6 months, mostly with full-thickness grafts, Greenstein said. Mean keratometry flattened by about 9.6 D at 1 month; at 6 months, that average was about 5.7 D, he said.
Further study to determine the efficacy of the procedure is underway.
Editor’s note: On Jan. 13, 2021, this article was updated to include Greenstein’s affiliation.
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Greenstein SA, et al. Corneal tissue addition for KC: A novel procedure for patients with significant corneal thinning. Presented at: American Academy of Ophthalmology annual meeting; Nov. 13-15, 2020 (virtual meeting).
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