Article

Single intrastromal corneal implant favored for paracentral/peripheral cones

Placement of a single intrastromal corneal implant (Intacs, Addition Technology) appears to offer better results than double-segment placement when treating keratoconus in eyes with paracentral/peripheral cones, said Colin C. Chan, MD.

Placement of a single intrastromal corneal implant (Intacs, Addition Technology) appears to offer better results than double-segment placement when treating keratoconus in eyes with paracentral/peripheral cones, said Colin C. Chan, MD.

Dr. Chan presented the results from a retrospective study comparing the two techniques. It was conducted at the Boxer Wachler Vision Institute, Beverly Hills, CA, in conjunction with Dr. Chan's co-author, Brian S. Boxer Wachler, MD.

The study included 20 eyes of 17 patients that underwent double-segment placement and 17 eyes of 11 patients that had a single segment placed. Most of the single-segment procedures were done with the 0.25-mm insert and for the double-segment technique, the most common combination used was a 0.25-mm segment above and a 0.35-mm segment below. All patients had peripheral cones and all of the surgeries were done with the axis of incision in the meridian of the steepest axis. The two study groups were also matched preoperatively.

The results showed significantly better outcomes in the single-segment group for all comparisons of change in cylinder, keratometry values, uncorrected visual acuity, and best-corrected visual acuity (BCVA). Overall, the eyes that had two corneal implants placed achieved an average of 1 line improvement in BCVA compared with a 2 to 3 line gain in the single-segment group.

"It is pretty well accepted that Intacs have a role in the management of keratoconus, but there remains heated debate about whether a single- or double-segment approach should be used," Dr. Chan said. "Our results support a single-segment approach in eyes with paracentral/peripheral cones, and we think there are two reasons to explain its benefits.

"First, keratoconus is a disease of corneal asymmetry with a steep area below and a flat area above, and so in using the segments to flatten the cornea," Dr. Chan said. "It seems to make sense to just place a single-segment below. In addition, segment placement appears to have a corneal coupling effect that is analogous to sitting on a beanbag - 'sitting' on one end causes the other to pop up."

Newsletter

Don’t miss out—get Ophthalmology Times updates on the latest clinical advancements and expert interviews, straight to your inbox.

Related Videos
(Image credit: Ophthalmology Times)  ASCRS 2025: Joaquin De Rojas, MD, leverages machine learning model to predict arcuate outcomes
(Image credit: Ophthalmology Times) ASCRS 2025: AnnMarie Hipsley, DPT, PhD, presents VESA for biomechanical simulation of presbyopia progression
Shehzad Batliwala, DO, aka Dr. Shehz, discussed humanitarian ophthalmology and performing refractive surgery in low-resource, high-risk areas at the ASCRS Foundation Symposium.
(Image credit: Ophthalmology Times) ASCRS 2025: Advancing vitreous care with Inder Paul Singh, MD
(Image credit: Ophthalmology Times) The Residency Report: Study provides new insights into USH2A target end points
Lisa Nijm, MD, says preoperative osmolarity testing can manage patient expectations and improve surgical results at the 2025 ASCRS annual meeting
At the 2025 ASCRS Annual Meeting, Weijie Violet Lin, MD, ABO, shares highlights from a 5-year review of cross-linking complications
Maanasa Indaram, MD, is the medical director of the pediatric ophthalmology and adult strabismus division at University of California San Francisco, and spoke about corneal crosslinking (CXL) at the 2025 ASCRS annual meeting
(Image credit: Ophthalmology Times) ASCRS 2025: Taylor Strange, DO, assesses early visual outcomes with femto-created arcuate incisions in premium IOL cases
(Image credit: Ophthalmology Times) ASCRS 2025: Neda Shamie, MD, shares her early clinical experience with the Unity VCS system
© 2025 MJH Life Sciences

All rights reserved.