Impact of corneal cross-linking on topical drug penetration in humans.
OBJECTIVE
To analyse the influence of corneal cross-linking (CXL) with ultraviolet-A (UV-A) and riboflavin on drug permeability in human subjects.


METHODS
Keratoconus patients (n = 23; mean age 26.9 ± 5.8 years) undergoing a standard CXL procedure with UV-A (5.4 J/cm(2) , 30 min) and riboflavin in one eye were included in the study. The pupillary diameter, measured before and every 3 min for 30 min after the topical application of one drop of 2% pilocarpine, was used as an indirect measure of the corneal permeability. The pupillary diameter was measured with an infrared pupillometer device before (baseline) and 4 months after CXL.


RESULTS
Prior to pilocarpine application, no significant difference in the pupillary diameter was detected before CXL and 4 months later. The mean decrease in the pupillary diameter after the application of pilocarpine was similar at baseline and the 4-month follow-up visit: mean decreases of 3.9 and 3.7 mm were observed 30 min after pilocarpine application, respectively (p > 0.05).


CONCLUSIONS
No significant influence of CXL on the corneal penetration of topically applied pilocarpine was observed in this clinical study.
Department of Ophthalmology, Inselspital, University of Bern, Bern, Switzerland.
Christoph
C
Tappeiner
Department of Ophthalmology, Inselspital, University of Bern, Bern, Switzerland.
Markus
M
Tschopp
Department of Ophthalmology, Inselspital, University of Bern, Bern, Switzerland.
Kaspar
K
Schuerch
Department of Ophthalmology, Inselspital, University of Bern, Bern, Switzerland.
Beatrice E
BE
Frueh
D000287:Administration, Topical; D000328:Adult; D003094:Collagen / Q000378:metabolism; D003319:Corneal Stroma / Q000378:metabolism*; D019781:Corneal Topography; D003432:Cross-Linking Reagents; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000378:metabolism*; D008297:Male; D018721:Muscarinic Agonists / Q000493:pharmacokinetics*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D010862:Pilocarpine / Q000493:pharmacokinetics*; D011680:Pupil / Q000502:physiology; D012256:Riboflavin / Q000627:therapeutic use; D014466:Ultraviolet Rays; D055815:Young Adult
D003432:Cross-Linking Reagents; D018721:Muscarinic Agonists; D017319:Photosensitizing Agents; D010862:Pilocarpine; D003094:Collagen; D012256:Riboflavin
cornea; corneal cross-linking; drug penetration; in vivo; keratoconus; pilocarpine; pupillometry