Initial results from mechanical compression of the cornea during crosslinking for keratoconus

Abstract

ABSTRACT.Purpose: To compare refractive changes after corneal crosslinking with and without mechanical compression of the cornea. Methods: In a prospective, open, randomized case-control study conducted at the Department of Ophthalmology, Ume a University Hospital, Sweden, sixty eyes of 43 patients with progressive keratoconus aged 18-28 years planned for corneal crosslinking and corresponding age-and sex-matched control subjects were included. The patients were randomized to conventional corneal crosslinking (CXL; n = 30) or corneal crosslinking with mechanical compression using a flat rigid contact lens sutured to the cornea during treatment (CRXL; n = 30). Subjective refraction and ETDRS best spectacle-corrected visual acuity (BSCVA), axial length measurement, keratometry and pachymetry were performed before and 1 and 6 months after treatment. Results: The keratoconus patients had poorer BSCVA, higher refractive astigmatism and higher keratometry readings than the control subjects at baseline (p < 0.01). In the CXL group, BSCVA increased from 0.19 AE 0.26 to 0.14 AE 0.18 logMar (p = 0.03), and the spherical equivalent improved from À1.9 AE 2.8 D to À1.4 AE 2.4 D (p = 0.03). Maximum keratometry readings decreased after CXL from 53.1 AE 4.9 D to 52.6 AE 5.2 D (p = 0.02), and the axial length decreased in the CXL group, likely due to post-treatment corneal thinning (p = 0.03). In the CRXL group, all the above variables were unaltered (p > 0.05). Conclusion: At 6 months, the refractive results from CRXL did not surpass those of conventional CXL treatment. Rather, some variables indicated a slightly inferior effect. Possibly, stronger crosslinking would be necessary to stabilize the cornea in the flattened configuration achieved by the rigid contact lens.

Increased Corneal Hysteresis After Corneal Collagen Crosslinking

“….86 (27) <.001 (27) <.001 (27) .56 (26) .01 (22) .13 (29) <.001 (29) .006 (29) 1 mo, mean (SD) 13.4 (2. (29) .25 (27) .16 (24) .95 (28) <.001 (29) .01 (29) 6 mo, mean (SD) 13.6 (3.1) 10.9 (1. (29) .59 (29) .20 (29) .54 (29) <.001 (29) .04 (29) Abbreviations: ART, applanation resonance tonometer; CH, corneal hysteresis; CRF, corneal resistance factor; CT min , corneal thickness at the thinnest point; CXL, corneal collagen crosslinking; GAT, Goldmann applanation tonometry; IOP, intraocular pressure; ORA, ocular response analyzer.…”

Treatment Effect and Corneal Light Scattering With 2 Corneal Cross-linking Protocols

“…This study involves patients treated with standard CXL and cross-linking with mechanical compression of the cornea using a flat rigid contact lens sutured to the cornea during the treatment, which we termed corneal reshaping and cross-linking (CRXL). 16 Given the spatial relationship between corneal haze and cross-linking and the fact that both appear to be related to the degree of irradiation, we hypothesize that quantification of the light scattering may be an indirect way to quantify the treatment effect of CXL as a complement to biomechanical and structural evaluations. The aim of this study was to assess the spatial distribution and time course of corneal densitometry changes after CXL and CRXL and their relationship to biomechanical and structural changes due to the treatments.…”

Morphologische Hornhautveränderungen nach Crosslinking bei Keratokonus

“…Trotz der bereits berichteten großen Datenmenge, gab es zu diesem Zeitpunkt nur 7 [110][111][112][113][114][115][116] bzw. 12 [117][118][119][120][121][122][123][124][125][126][127][128] randomisierte Studien, in denen ein Vergleich zwischen dem Dresden-Protokoll und einer unbehandelten Kontrollgruppe bzw. anderen Protokollen durchgeführt wurde.…”

“…Aufgrund von verschiedenen Unklarheiten wurden nur 3 [110,112,114] bzw. 9 [117,118,[123][124][125][126][127] dieser Studien berücksichtigt. Das IQWiG bezeichnete die vorliegende Datenlage als "hoch verzerrt und unvollständig".…”