Treatment of Keratoconus With Advanced Corneal Crosslinking

The purpose of this study was to determine whether mechanical compression of the cornea during corneal crosslinking for keratoconus using a sutured rigid contact lens can improve the optical outcomes of the treatment.

The study is designed as a prospective, open, randomized controlled trial involving patients aged 18-28 years of both genders with uni- or bilateral keratoconus planned for routine corneal crosslinking at the Department of Ophthalmology, Umeå University Hospital, Umeå, Sweden. The study involves 30+30 eyes with keratoconus, which are randomized to receive either conventional corneal crosslinking (n=30) using the Dresden protocol or a modified treatment - corneal reshaping and crosslinking (n=30), where a rigid contact lens is sutured to the cornea during the treatment to flatten the corneal curvature and potentially improve the optical outcome after the treatment. Patients are randomized utilizing a list of unique random numbers between 1 and 60. All patients are informed about the procedures before consenting to participate in the study. The study also involves 60 eyes of healthy age- and sex-matched control subjects. At baseline, before treatment, each eye is evaluated with autorefractometer measurement, best spectacle-corrected LogMAR visual acuity, Pentacam Scheimpflug photography, Goldmann applanation tonometry and biomicroscopy. The corneal biomechanical characteristics are assessed with applanation resonance tonometry and the ocular response analyzer. The investigations are repeated at 1 month, 6 months, 2 years and 5 years after the treatment.

Keratoconus, Corneal crosslinking, Corneal biomechanics, Corneal densitometry, Scheimpflug photography

Corneal crosslinking with compression of the cornea using a sutured rigid contact lens during the treatment.

The keratoconus cornea is treated with epithelial debridement in local anesthesia, is soaked in Riboflavin by repeated topical application during 30 minutes. A flat, rigid contact lens is sutured to the cornea and the cornea and is then irradiated with ultraviolet light 5.4 J/cm2 during 30 minutes.

The keratoconus cornea is treated with epithelial debridement in local anesthesia, is soaked in Riboflavin by repeated topical application during 30 minutes. The cornea and is then irradiated with ultraviolet light 5.4 J/cm2 during 30 minutes.

Uncorrected and best spectacle corrected visual acuity measured with the Early treatment diabetic retinopathy study, graded in logarithmic values of the minimal angle of resolution

Inclusion Criteria: Patients planned for corneal crosslinking. Progressive keratoconus documented with Scheimpflug photography using the Pentacam Scheimflug camera and/or repeated subjective refraction and keratometry. A keratoconus diagnosis based on the Amsler-Krumeich grading and the "Total Deviation" KC quantification value from the "Belin-Ambrosio enhanced ectasia" measurements of the Pentacam Scheimpflug camera, and an altered red reflex and/or an irregular cornea seen as distortion of the keratometric mires. Minimum corneal thickness of 400 µm at the thinnest point after epithelial removal. 18-28 years of age No ocular abnormalities except keratoconus No previous ocular surgery No cognitive insufficiency interfering with the informed consent. Exclusion Criteria: Age under 18 or over 28 Any corneal abnormalities except keratoconus Previous ocular surgery Cognitive insufficiency.

Beckman Rehnman J, Behndig A, Hallberg P, Linden C. Initial results from mechanical compression of the cornea during crosslinking for keratoconus. Acta Ophthalmol. 2014 Nov;92(7):644-9. doi: 10.1111/aos.12380. Epub 2014 Mar 15.

Beckman Rehnman J, Behndig A, Hallberg P, Linden C. Increased corneal hysteresis after corneal collagen crosslinking: a study based on applanation resonance technology. JAMA Ophthalmol. 2014 Dec;132(12):1426-32. doi: 10.1001/jamaophthalmol.2014.3029.

Beckman Rehnman J, Janbaz CC, Behndig A, Linden C. Spatial distribution of corneal light scattering after corneal collagen crosslinking. J Cataract Refract Surg. 2011 Nov;37(11):1939-44. doi: 10.1016/j.jcrs.2011.05.028. Epub 2011 Aug 27.

Rehnman JB, Linden C, Hallberg P, Behndig A. Treatment Effect and Corneal Light Scattering With 2 Corneal Cross-linking Protocols: A Randomized Clinical Trial. JAMA Ophthalmol. 2015 Nov;133(11):1254-60. doi: 10.1001/jamaophthalmol.2015.2852.