Abstract
Keratoconus is an ectatic disorder that is presently considered one of the most prevalent reasons for keratoplasty. Corneal collagen crosslinking (CXL) is the only proven treatment option available that is capable of halting the progression of the disease by stabilizing the cone in 90% of cases, and by also reducing refractive error and maximal keratometry. This study assesses, by means of a 3D morphogeometric analysis procedure developed by our research team, the corneal structure changes that occur immediately after CXL treatment and during a 6 month follow-up period. A total of 19 eyes from 19 patients diagnosed with keratoconus who underwent CXL were included, and several variables derived from the morphogeometric analysis were calculated and evaluated for the pre-operative, 3 month postoperative, and 6 month postoperative states. Significant reductions were detected in central corneal thickness and corneal spherical-like root mean square (RMS) 3 months after surgery, with non-significant regression of the effect afterward. Significant reductions in the total corneal area/volume were found, with some levels of regression after 6 months in certain volumetric parameters. In conclusion, the eyes with higher values for morphogeometric parameters—posterior apex deviation (PAD), anterior minimum thickness point deviation (AMTPD), and posterior minimum thickness point deviation (PMTPD)—seemed more likely to undergo aberrometric improvement as a result of CXL surgery.
Highlights
Keratoconus (KC) is an ectatic disorder characterized by progressive thinning, steepening, and distortion of the cornea, with secondary loss of vision due to unacceptable levels of irregular astigmatism [1]
CXL, first introduced by Spoerl and Seiler at the University of Dresden in 1996 [5], consists in inducing the formation of chemical bridges between the collagen fibers within the corneal stroma to increase their stiffness and to avoid further cornea deformation. This is achieved by irradiation with ultraviolet A light (UVA), performed on a corneal stroma previously soaked with riboflavin
Significant reductions were detected during the follow-up in the central corneal thickness (CCT) (p = 0.006) and the corneal spherical-like root mean square (RMS) (p = 0.030) at 3 months after surgery, with a non-significant regression of the effect afterward (p = 0.084)
Summary
Keratoconus (KC) is an ectatic disorder characterized by progressive thinning, steepening, and distortion of the cornea, with secondary loss of vision due to unacceptable levels of irregular astigmatism [1]. About 12–20% of keratoconus patients will require corneal transplantation for their visual rehabilitation [2], which implies several potential drawbacks, such as Diagnostics 2020, 10, 397; doi:10.3390/diagnostics10060397 www.mdpi.com/journal/diagnostics. CXL, first introduced by Spoerl and Seiler at the University of Dresden in 1996 [5], consists in inducing the formation of chemical bridges (crossed links) between the collagen fibers within the corneal stroma to increase their stiffness and to avoid further cornea deformation. This is achieved by irradiation with ultraviolet A light (UVA), performed on a corneal stroma previously soaked with riboflavin (vitamin B2). CXL stabilizes the cone at a success rate over 90%, and improves ectasia to some extent with an average reduction of 1D in refractive error, and of 2D in maximal keratometry, while visual acuity remains unchanged or improves by about 1–2 lines [6]
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