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Vishal Jhanji, Yumeng Wang, Tommy Chung Yan Chan, Marco Yu; Shift in Progression Rate of Keratoconus before and after Corneal Collagen Crosslinking. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5565.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the shift in keratoconus progression rate before and after corneal collagen crosslinking
Patients with keratoconus were followed up every 3 to 4 months before surgery. Slit lamp examination, visual acuity measurement and corneal topography was performed at each visit. Accelerated crosslinking was performed (365-nm, 18-mW/cm2 irradiance, 5 minutes) after documentation of ≥1.00 D change in refractive astigmatism, loss of ≥ 2 lines of best-corrected visual acuity or ≥1 diopter (D) increase in the steepest keratometry (Ks). Postoperatively, patients were followed up on day 1, day 3, week 1, month 1, month 3, and every 3 months thereafter. The main outcome parameters were rates of progression for anterior and posterior Ks, flat keratometry (Kf), average keratometry (Avg K), best-fit sphere (BFS), and spherical equivalent (SEQ) were estimated before and after crosslinking using linear mixed effect models. Log-likelihood was used to compare the strength of association between different preoperative parameters and postoperative progression rate of anterior or posterior Avg K.
Forty-seven eyes of 38 patients (mean age 27.6 ± 6.5 years) were included. The median number of preoperative and postoperative visits was 3 (median follow-up, 13 months) and 6 (median postoperative follow-up, 20 months) respectively. Postoperatively, significant changes in mean progression rate were observed in anterior Ks, Kf, Avg K and BFS, posterior Ks, Avg K and BFS (p ≤ 0.001). A significant reduction in progression rate of anterior (0.063 ± 0.138 D/month to -0.033 ± 0.039 D/month) and posterior Avg K (-0.011 ± 0.025 D/month to 0.000 ± 0.008 D/month) was observed after crosslinking (p < 0.001 for both). Univariate analysis demonstrated that baseline anterior Avg K had the strongest association with the progression rate of anterior Avg K after crosslinking (log-likelihood -264.7). Multivariate analysis showed that baseline SEQ and anterior Ks were the most important parameters associated with postoperative progression rate of anterior Avg K (log-likelihood -206.7) (p < 0.001).
Crosslinking results in significant slowing down of keratoconus progression. Corneal topographical parameters are more sensitive to gauge the shift in disease progression after collagen crosslinking as compared to corneal thickness and refraction.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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