Prospective, randomized contralateral eye study of accelerated and conventional corneal cross-linking in pediatric keratoconus
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To compare the outcomes of two different cross-linking (CXL) protocols, in pediatric keratoconus eyes.
Materials and methods
In this prospective randomized contralateral eye interventional study, 68 eyes of 34 patients, 9–16 years old, underwent CXL and enrolled between October 2011 and October 2013. Group A represents conventional riboflavin–ultraviolet A (UVA)-induced CXL with 30 min of exposure to UVA irradiation of 3 mW/cm2. Group B represents accelerated cross-linking with 5 min of continuous UVA irradiation of 18 mW/cm2. In either group, total energy delivered was adjusted to 5.4 J/cm2. Follow-up of all patients was accomplished throughout the postoperative 3 years, and the data from the preoperative, 12, 24, and 36 months visits were analyzed and compared in both groups. Uncorrected visual acuity, corrected distance visual acuity, steepest keratometry (Kmax), corneal astigmatism (simulated K), total wavefront aberrations, central corneal thickness (CCT), corneal densitometry, manifest refraction spherical equivalent, and endothelial cell density (ECD) were evaluated at baseline, 12, 24, and 36 months post-CXL.
At 1-year assessment, the mean value of UCVA, CDVA, and Kmax showed a statistically significant difference between both groups, without any documented change in the variables throughout the remaining follow-up (1–3-year) period. Twelve months postoperatively, mean LogMAR UCVA and CDVA were (0.11 ± 1.60) and (0.03 ± 1.60), respectively, in accelerated CXL group, compared to conventional CXL group values of (0.20 ± 1.00) and (0.06 ± 1.22), showing a statistically significant difference (P < 0.05). Mean Kmax in accelerated CXL group (45.47 ± 0.44) showed a statistically significant difference (P < 0.05) compared to conventional CXL group (46.41 ± 1.59) at 12 months post-CXL. On the other hand, wavefront aberrations, simulated K, corneal densitometry, ECD, and CCT changes showed nonstatistically significant difference in conventional CXL group, compared to accelerated CXL group (P > 0.05) throughout the follow-up course.
Both conventional and accelerated CXL improved UCVA and CDVA, attenuated disease progression, and reduced corneal steepness and wavefront aberrations at 1, 2, and 3 years postoperatively. In no case did keratoconus progress over the 36-month follow-up.
KeywordsAccelerated Conventional Cross-linking Pediatric Keratoconus
The authors thank Dr Ahmed Ibrahim for referring cases of pediatric keratoconus and his independent follow-up of cases.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The study adhered to the tenets of Declaration of Helsinki, and IRB approval was obtained from an ethical committee—Magrabi Aseer Hospital.
An informed consent was obtained from all parents.