Depth evaluation of intended vs actual intacs intrastromal ring segments using optical coherence tomography

Abstract

Purpose Evaluation of actual vs intended intrastromal corneal ring segments (ICRS) implantation depth as measured by anterior segment optical coherence tomography (OCT) Methods Prospective study evaluating 30 Intacs segments implanted manually in 19 eyes of 15 patients suffering from keratoconus. Segment depth evaluation was performed using anterior segment OCT. Measurements were performed above and below the segment at 3 points in relation to the incision site. Statistical analysis was performed using the SAS software for ANOVA, matched t-test, and GLIMMIX procedure. Results Intacs segment depth was 153-μm shallower than intended (58% vs 80%). Segment layout demonstrated the proximal and distal portions to be 13-μm shallower and 12-μm deeper (on average), respectively. Intacs segment thickness does not influence implantation depth. Intacs segments implanted in the same eye do not share similar implantation depths. Stromal compression is likely to occur. Conclusion Intacs are implanted at a shallower depth than intended. The 'pocketing' stage prior to implantation most likely has a stronger effect on the segment's final implantation depth than does the incisions' depth.

Predictability of Tunnel Depth for Intrastromal Corneal Ring Segments Implantation Between Manual and Femtosecond Laser Techniques

“…Most of the previous studies 9, 10,12,14 published about this subject report on the use of Intacs ICRS and do not Predictability of ICRS Tunnel Depth/Monteiro et al compare both techniques. Barbara et al 10 studied with OCT the depth of implantation of Intacs ICRS after manual surgery.…”

“…Most of the previous studies 9, 10,12,14 published about this subject report on the use of Intacs ICRS and do not Predictability of ICRS Tunnel Depth/Monteiro et al compare both techniques. Barbara et al 10 studied with OCT the depth of implantation of Intacs ICRS after manual surgery. Our results, with a larger sample, confirm those reported in this previous study, in which the authors found a shallower than planned intrastromal tunnel performed by mechanical dissection (308 µm instead of the expected 461 µm; P < .05).…”

“…The tunnel can be created with manual dissection or assisted by a femtosecond laser device. Previous publications regarding this aspect present conflicting results, but most studies report shallower depth than predicted and no difference between manual or femtosecond laser-assisted surgery [8][9][10][11][12] ; all studies but one were performed with Intacs ICRS (Addition Technology Inc., Des Plaines, IL). The reasons for such differences reported arise mainly because the methods of measurement differ, whether regarding the device being used (Scheimpflug tomography or optical coherence tomography) or the location used for the measurement.…”

Anterior segment optical coherence tomography and its clinical applications

“…Ring segments can also be inserted deep into the corneal stroma to correct corneal curvature in keratoconus. AS‐OCT can determine the position of the ring segments during implantation, and prevent unwanted complications, including anterior chamber perforation or epithelial‐stromal breakdown …”

Corneal Hydrops Secondary to Intrastromal Corneal Ring Intrusion into the Anterior Chamber 7 Years after Implantation: A Case Report

“…In order to avoid complications associated with shallow segment implantation, aiming for an implantation depth of 70% total corneal thickness is common practice [ 12 , 13 ]. Using three points above and below the implantation site, we calculated the average depth of our patient’s INTACS segment to be 75.08% total corneal thickness [ 13 ]. It is unclear if this depth was part of the surgical plan or if it was due to posterior migration of the implant.…”