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Spatial distribution of corneal light scattering after corneal collagen crosslinking
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
2011 (English)In: Journal of cataract and refractive surgery, ISSN 0886-3350, E-ISSN 1873-4502, Vol. 37, no 11, 1939-1944 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: To assess the spatial distribution and time course of increased corneal light scattering after corneal collagen crosslinking (CXL) with riboflavin and ultraviolet-A irradiation.

Setting: Umeå University Hospital Eye Clinic, Umeå, Sweden.

Design: Case series.

Methods: Eyes with keratoconus were examined with Scheimpflug photography before and 1 and 6 months after CXL. Corneal light scattering was quantified throughout the corneal thickness at 8 measurement points 0.0 to 3.0 mm from the central cornea.

Results: The study comprised 11 eyes of 11 patients. Central corneal light scattering increased significantly 1 month after CXL (P<.001). At 6 months, it decreased (P=.002); however, it was still higher than pretreatment values (P<.001). Light scattering at 1 month was more pronounced in the superficialstroma, gradually diminishing to zero at 240 μm depth. It was greater at the corneal center than 1.0 to 3.0 mm from the center. At 6 months, a second peak of light scattering occurred between 240 μm and 340 μm depth. No increased light scattering deeper than 340 μm was seen at either time point.

Conclusions: Corneal light scattering after CXL showed distinctive spatial and temporal profiles. Analysis of corneal light scattering may give an impression of tissue changes, the depth of the CXL treatment effect, and the corneal response to the treatment. Scheimpflug photography appears to be useful for this purpose.

Place, publisher, year, edition, pages
Fairfax,Va.: American Society of Cataract and Refractive Surgery , 2011. Vol. 37, no 11, 1939-1944 p.
National Category
Ophthalmology
Identifiers
URN: urn:nbn:se:umu:diva-50416DOI: 10.1016/j.jcrs.2011.05.028ISI: 000296678400005OAI: oai:DiVA.org:umu-50416DiVA: diva2:464277
Conference
ASCRS Symposium on Cataract, IOL and Refractive Surgery, San Diego, CA, MAR, 2011
Available from: 2011-12-13 Created: 2011-12-08 Last updated: 2017-12-08Bibliographically approved
In thesis
1. New methods to evaluate the effect of conventional and modified crosslinking treatment for keratoconus
Open this publication in new window or tab >>New methods to evaluate the effect of conventional and modified crosslinking treatment for keratoconus
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Today corneal crosslinking with ultraviolet-A photoactivation of riboflavin is an established method to halt the progression of keratoconus. In some cases, when the refractive errors are large and the visual acuity is low, conventional corneal crosslinking may not be sufficient. In these cases it would be desirable with a treatment that both halts the progression and also reduces the refractive errors and improves the quality of vision.

Aims:  The aims of this thesis were to determine whether mechanical compression of the cornea during corneal crosslinking for keratoconus using a sutured rigid contact lens could improve the optical and visual outcomes of the treatment, and also to find methods to evaluate the effect of different corneal crosslinking treatment regimens.

Methods: In a prospective, open, randomized case-control study, 60 eyes of 43 patients with progressive keratoconus, aged 18-28 years, planned for routine corneal crosslinking, and a corresponding age- and sex-matched control group was included. The patients were randomized to conventional corneal crosslinking (CXL; n=30) or corneal crosslinking with mechanical compression of the cornea during the treatment (CRXL; n=30).

Biomicroscopy, autorefractometry, best spectacle corrected visual acuity, axial length measurement, Pentacam® HR Scheimpflug photography, pachymetry, intraocular pressure measurements and corneal biomechanical assessments were performed before treatment (baseline) and at 1 month and 6 months after the treatment.

One of the articles evaluated and compared the optical and visual outcomes between CXL and CRXL, while the other three articles focused on methods to evaluate treatment effects. In Paper I, the corneal light scattering was manually quantified from Scheimpflug images throughout the corneal thickness at 8 measurements points, 0.0 to 3.0 mm from the corneal centre, in patients treated with CXL. In Paper IV the corneal densitometry (light scattering) was measured with the Pentacam® HR software, in 4 circular zones around the corneal apex and at 3 different depths of the corneal stroma, in both CXL and CRXL treated corneas. Paper III quantified the biomechanical effects of CXL in vivo.

Results: Corneal light scattering after CXL showed distinctive spatial and temporal profiles and Applanation Resonance Tonometry (ART) -technology demonstrated an increased corneal hysteresis 1 and 6 months after CXL. When comparing the refractive and structural results after CXL and CRXL, CRXL failed to flatten the cornea, and the treatment did not show any benefits to conventional CXL treatment, some variables even indicated an inferior effect. Accordingly, the increase in corneal densitometry was also less pronounced after CRXL.

Conclusions: Analysis of corneal light scattering/densitometry shows tissue changes at the expected treatment location, and may be a relevant variable in evaluating the crosslinking effect. ART -technology is an in vivo method with the potential to assess the increased corneal hysteresis after CXL treatment. By refining the method, ARTmay become a useful tool in the future. Unfortunately, CRXL does not improve the optical and visual outcomes after corneal crosslinking. Possibly, stronger crosslinking would be necessary to stabilize the cornea in a flattened position.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2015. 57 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1746
Keyword
Keratoconus, crosslinking, light scattering, densitometry, keratometry, hysteresis, intraocular pressure
National Category
Ophthalmology
Research subject
Ophtalmology
Identifiers
urn:nbn:se:umu:diva-110531 (URN)978-91-7601-336-6 (ISBN)
Public defence
2015-11-20, Hörsal 914, Unod B 9, Norrlands universitetssjukhus, Umeå, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2015-10-30 Created: 2015-10-22 Last updated: 2015-10-30Bibliographically approved

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Beckman Rehnman, JeannetteBehndig, AndersLindén, Christina

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