Impact of keratoconus stage on outcome after corneal crosslinking

Abstract

Background This study aimed to analyze if the outcome after corneal crosslinking (CXL) in progressive keratoconus patients depends on the stage at which the procedure is performed. This knowledge would help to improve success of CXL and to define surgery indications in those patients. Methods In this retrospective study, 124 consecutive eyes of 100 patients with progressive keratoconus undergoing corneal CXL at the University Eye Hospital Tübingen were included. The eyes were graded according to modified Krumeich stages depending on induced myopia or astigmatism, corneal radii, minimum corneal thickness, and morphological changes. The observation period covered November 2008 to September 2018. Preoperatively, 12 and 24 months after CXL, the best corrected visual acuity (BCVA) was determined and astigmatism as well as tomographic parameters (Kmax, Kmin, central corneal thickness (CCT), minimum corneal thickness (MCT)) were measured by means of a Scheimpflug camera system. Results BCVA results showed significant differences between the modified Krumeich stages at 12 months (p = 0.014) and at 24 months postoperatively (p = 0.032). Also, astigmatism differed significantly among the stages at 24 months after CXL (p = 0.023). However, no significant differences regarding astigmatism were detectable after 12 months. In terms of Kmax, Kmin, CCT, and MCT, no significant differences between the Krumeich stages were observed. Conclusions BCVA showed a significantly higher improvement after CXL in the early stage of keratoconus compared to a higher stage. However, the postinterventional tomographic values did not differ significantly between the different modified Krumeich stages. The significantly higher improvement in BCVA after CXL in the early stage might indicate that earlier intervention provides a higher subjective benefit to the individual. Further studies with larger sample sizes are needed to confirm these findings.

Keratoconus: exploring fundamentals and future perspectives – a comprehensive systematic review

“… 78 – 80 Cross-linking, as a ‘green light’ for keratoconus stabilization, opened a new door of therapeutic refractive surgery to ‘reshape’ the keratoconic cornea and postpone or even avoid corneal transplantation. 18 , 81 …”

Assessment of Health Disparities and Barriers to Accessing Keratoconus and Crosslinking at a Tertiary Referral Center

“…Specific targeting of vulnerable populations, M aori and Pacific Peoples, will likely make a significant difference downstream economically and reduce health disparities between ethnicities. 24,25…”

Corneal collagen cross-linking in patients with keratoconus from the Dresden protocol to customized solutions: theoretical basis

“…The standard protocol involves the removal of the epithelium, followed by 30min of imbibition of the corneal parenchyma with a riboflavin-dextran solution. The second phase consists of 6 steps of 5min each of UV-A irradiation (370 nm), associated with the instillation of two drops of riboflavin every 5min, with a fixed intensity of the power heuristically defined at 3 mW/cm 2 for a total energy of 5.4 J/cm 2 [11][12][13] . The removal of the epithelium (EPI-OFF technique) is motivated by the need for rapid and suitable absorption of riboflavin in the corneal parenchyma.…”

“…This photochemical reaction increases corneal stiffness, collagen fibers thickness, and resistance to enzymatic degradation, especially in the anterior stroma [8][9] . Since the late 1990s, numerous papers published in international peer-reviewed journals have reported promising clinical results on the use of CXL in the treatment of progressive keratoconus [10][11][12] . Thanks to CXL, an increase in the stiffness of the stroma of over 300% is reported, with an increase in the diameter of the collagen fibers by 12.2% and the formation of cross-linked bonds in the collagen structure [13][14][15] .…”