Related Experiment Video
Updated: May 16, 2025
Three Different Protocols of Corneal Collagen Crosslinking in Keratoconus: Conventional, Accelerated and Iontophoresis
Published on: November 12, 2015
New technique for enhancing the astigmatic correction of intracorneal ring segments in keratoconus eyes with a
Yara Bteich1, Carl-Joe Mehanna1, Maamoun A Fattah1
1Department of Ophthalmology, American University of Beirut Medical Center, Beirut, Lebanon.
Purpose:
The purpose of this study was to present a case series describing a new simple technique of intrastromal corneal ring segment (ICRS) implantation that shortens the effective arc length of a segment and amplifies its effect on the corneal cylinder.
Methods:
A 150° ICRS designed to be implanted in the 6-mm optical zone (OZ) (Intacs® SK) was instead implanted in a 7-mm OZ channel using a femtosecond laser.
Results:
The decrease in manifest refraction spherical equivalent (MRSE) at 6 months was significantly less for the SK-7 group compared to the SK-6 group (2.21 ± 0.86 D vs. 8.87 ± 3.22 D, P = 0.004, respectively). The average central corneal power was also more pronounced in the SK-6 group (-2.19 ± 0.98D vs. -4.50 ± 2.87D, P = 0.20, respectively). Greater reduction in corneal and refractive cylinder magnitude (SimK) and vector was observed when Intacs® SK segments were implanted at 7-mm instead of 6-mm OZ. The SK-7 group gained more Corrected distance visual acuity (CDVA) lines at 6 months. The vector analysis variables including surgically induced astigmatic vector, difference vector, correction index, and index of success were all better when Intacs® SK was implanted at 7 mm.
Conclusion:
Shortening the effective arc length of the ICRS to 129° resulted in greater astigmatism correction with less effect on overall corneal flattening and MRSE. This technique would allow the surgeon to obtain a different effective ICRS arc length from the actual one and can be useful to reduce the inventory of ICRS in a given center.
