Optical coherence tomography to assess intrastromal corneal ring segment depth in keratoconic eyes.
OBJECTIVE
To investigate intrastromal corneal ring segment depth with a high-speed corneal optical coherence tomography (OCT) system.


METHODS
Doheny Eye Institute, University of Southern California, Los Angeles, California, USA.


METHODS
A prospective observational case series comprised 4 eyes of 4 patients receiving Intacs intrastromal corneal ring segments (Addition Technology, Inc.) for keratoconus. Optical coherence tomography (OCT) was performed between 7 days and 43 days after implantation.


RESULTS
The slitlamp impression of intrastromal corneal ring segment implantation depth did not correlate well with OCT measurements (r(2) = 0.68). The fractional implantation depth was correlated with several surgical variables using a stepwise multivariate regression model, and 2 statistically significant correlations were found. The position of the distal portions of the ring segments was shallower than that of the portion closer to the insertion site (P = .003). Segments placed in the inferior cornea (P = .008) experienced more distal shallowing. Shallower depth was associated with greater fractional anterior stromal compression (P = .04).


CONCLUSIONS
Shallower placement of intrastromal corneal ring segments may result in more complications, such as epithelial-stromal breakdown and extrusion, because of the greater anterior stromal tensile strain. The distal and inferior portions of intrastromal corneal ring segments tended to be placed at a shallower depth. Optical coherence tomography provided precise measurement of ring segment depth and may help identify implants that pose a greater risk for depth-related complications.
Lai
Michael M
MM
Doheny Eye Institute and Department of Ophthalmology, University of Southern California, Los Angeles, California, USA.
Tang
Maolong
M
Andrade
Eduardo M M
EM
Li
Yan
Y
Khurana
Rahul N
RN
Song
Jonathan C
JC
Huang
David
D
D000328:Adult; D003319:Corneal Stroma / Q000473:pathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D041623:Tomography, Optical Coherence / Q000379:methods*