ABSTRACT
PURPOSE: To report refractive, topographic, and biomechanical outcomes, efficiency, and safety of corneal collagen crosslinking (CXL) 1, 3, 6, and 12 months after treatment. SETTING: National Reference Centre for Keratoconus, Bordeaux and Toulouse, France. DESIGN: Case series. METHODS: This retrospective uncontrolled double-center study comprised eyes with progressive keratoconus. Uncorrected distance visual acuity, corrected distance visual acuity (CDVA), corneal pachymetry, endothelial cell count, and corneal hysteresis and corneal resistance factor were evaluated at baseline and at 1, 3, 6, and 12 months. RESULTS: One hundred forty-two eyes were enrolled in the study. At 6 months, the CDVA had stabilized in 53 eyes (48.1%), improved in 36 eyes (32.7%), and decreased in 18 eyes (16.3%). At 12 months, the CDVA had stabilized in 31 eyes (47.6%), improved in 26 eyes (40.0%), and decreased in 8 eyes (12%). At 6 months, keratoconus progression had stopped in 51 eyes (49.03%) and the maximum keratometry (K) value had decreased by more than 1.0 diopter (D) in 37 eyes (35.5%); it continued to progress in 16 eyes (15.3%). At 12 months, keratoconus progression had stopped in 42 eyes (68.8%) and the maximum K value had decreased by more than 2.0 D in 13 eyes (21.3%). The complication rate with loss of vision was 3.5%. CONCLUSIONS: Ultraviolet-A light associated with riboflavin CXL is an efficient procedure to stabilize and improve progressive keratoconus. The results reinforce previous studies highlighting the efficacy and safety of the procedure. A large prospective randomized clinical trial is needed.
Subject(s)
Collagen/metabolism , Corneal Stroma/metabolism , Keratoconus/drug therapy , Biomechanical Phenomena/physiology , Cell Count , Corneal Endothelial Cell Loss/physiopathology , Corneal Topography , Cross-Linking Reagents/therapeutic use , Endothelium, Corneal/pathology , Female , Follow-Up Studies , Humans , Keratoconus/metabolism , Keratoconus/physiopathology , Male , Photosensitizing Agents/therapeutic use , Refraction, Ocular/physiology , Retrospective Studies , Riboflavin/therapeutic use , Tomography, Optical Coherence , Ultraviolet Rays , Visual Acuity/physiology , Young AdultABSTRACT
PURPOSE: To analyze the correlation between corneal hysteresis (CH) measured with the Ocular Response Analyzer (ORA, Reichert) and ultrasonic corneal central thickness (CCT US) and intraocular pressure measured with Goldmann applanation tonometry (IOP GA). SETTING: Bordeaux 2 University, Ophthalmology Department, Bordeaux, France. METHODS: This study comprised 498 eyes of 258 patients. Corneal hysteresis, corneal resistance factor (CRF), and IOP corneal-compensated (IOPcc) were provided by the ORA device; CCT US and IOP GA were also measured in each eye. The study population was divided into 5 groups: normal (n = 122), glaucoma (n = 159), keratoconus (n = 88), laser in situ keratomileusis (LASIK) (n = 78), and photorefractive keratectomy (n = 39). The Pearson correlation was used for statistical analysis. RESULTS: Corneal hysteresis was not strongly correlated with IOP or CCT US. The mean CH in the LASIK (8.87 mm Hg) and keratoconus (8.34 mm Hg) groups was lower than in the glaucoma (9.48 mm Hg) and normal (10.26 mm Hg) groups. The lower the CH, the lower its correlation with IOPcc and IOP GA. A CH higher than the CRF was significantly associated with the keratoconus and post-LASIK groups. CONCLUSIONS: Corneal hysteresis, a new corneal parameter, had a moderate dependence on IOP and CCT US. Weaker corneas could be screened with ORA parameters, and low CH could be considered a risk factor for underestimation of IOP. The CCT US should continue to be considered a useful parameter.
