Can we measure corneal biomechanical changes after collagen cross-linking in eyes with keratoconus?--a pilot study.
OBJECTIVE
To assess changes in biomechanical properties of human cornea after treatment of keratoconus with UV-A-riboflavin corneal collagen cross-linking (CXL).


METHODS
Single-center, prospective, interventional study.


METHODS
Ten eyes of 10 patients aged 26.5 +/- 5.7 (mean +/- SD) years with progressive keratoconus were treated with UV-A-riboflavin CXL and assessed with the Ocular Response Analyzer (ORA) that measured corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal compensated intraocular pressure (IOPcc). Intraocular pressure was also measured by Goldmann applanation tonometry (GAT-IOP). Patients were assessed with ORA preoperatively, at week 1, months 1, 3, and 6 after treatment. Postoperative measurements at each visit were compared with preoperative values.


RESULTS
CH and CRF were transiently elevated after cross-linking treatment, with the difference not statistically significant (P > 0.3). IOPcc and IOPg were statistically significantly higher at 1 week and 1 month but not subsequently (P < 0.04). GAT-IOP was statistically significantly higher at 1 week and at 1 and 3 months (P < 0.01).


CONCLUSIONS
There were no significant differences in corneal biomechanical properties, as measured with the ORA parameters CH and CRF, after CXL in keratoconus. IOPcc, IOPg, and GAT-IOP values were transiently elevated after CXL treatment in our study. Whether this reflects a measurement artifact resulting from corneal changes or true elevation of intraocular pressure is unclear.
Department of Ophthalmology, Assaf Harofeh Medical Center, Tel-Aviv University, Tel-Aviv, Israel.
Yakov
Y
Goldich
Yaniv
Y
Barkana
Yair
Y
Morad
Morris
M
Hartstein
Isaac
I
Avni
David
D
Zadok
D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D003094:Collagen / Q000187:drug effects*; D003315:Cornea / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D007640:Keratoconus / Q000503:physiopathology* / Q000628:therapy*; D008297:Male; D017319:Photosensitizing Agents / Q000627:therapeutic use; D010865:Pilot Projects; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D013997:Time Factors; D014065:Tonometry, Ocular; D014467:Ultraviolet Therapy; D055815:Young Adult
D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin