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Corneal collagen cross-linking with riboß avin and ultraviolet - A light for |
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| Aim : To assess the results of corneal collagen cross-linking with riboß avin using ultraviolet - A light for
keratoconus at one year in Indian eyes. Materials and Methods: Sixty-eight eyes of 41 patients with progressive keratoconus were included in this retrospective study. All eyes completed was 12 months of follow-up and 37 eyes had a one-year follow-up. The maximum follow-up was 16 months. Ocular examinations including refraction, best corrected visual acuity (BCVA), corneal topography, were recorded at each visit. |
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Results : The mean age was 16.9 ± 3.5 years (range 12-39 years) and the mean follow-up was 10.05 ± 3.55
months (range six to 16 months). Thirty seven eyes with a follow-up of at least 12 months were analyzed.
The preoperative values on the day of treatment were compared with postoperative values of the 12-month
examination. This showed that BCVA improved at least one line in 54% (20/37) of eyes and remained stable
in 28% (10/37) of eyes (P=0.006). Astigmatism decreased by a mean of 1.20 diopter (D) in 47% (17/37) of eyes
(P=0.005) and remained stable (within ± 0.50 D) in 42% (15/37) of eyes. The K value of the apex decreased by
a mean of 2.73 D in 66% (24/37) of eyes (P=0.004) and remained stable (within ± 0.50 D) in 22% (8/37) of eyes.
The maximum K value decreased by a mean of 2.47 D in 54% (20/37) of eyes (P=0.004) and remained stable
(within ± 0.50 D) in 38% (14/37) of eyes. Corneal Wavefront analysis revealed that spherical and higher-order
aberrations did not show signiÞ cant variations in the follow-up period. The coma component showed a very
signiÞ cant reduction at six months aft er treatment and persisted throughout the follow-up period (P=0.003). |
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| Conclusion : he results show a stabilization and improvement in keratoconus aft er collagen cross-linking in Indian eyes. This suggests that it is an eff ective treatment for progressive keratoconus. | |||
| Key words : Collagen cross-linking, cornea, progressive keratoconus, riboß avin, ultraviolet A
Indian J Ophthalmol: 2009;57:111-114 Keratoconus is characterized by the development of a nonin ß ammatory ectasia of the axial or peri-axial region of thecornea and is usually bilateral. Its incidence in the generalpopulation is reported to be about one in 2000.[1] Incidences of one in 600 to one in 420 seem more in keeping with the current diagnostic capacity.[2] Because of the young age of patients, keratoconus oft en has a signiÞ cant negative eff ect on the quality of life.[3] Two chief mechanisms for the development of keratoconus have been put forward. One proposes that ectasia is closely associated with tissue degradation or reduced maintenance,[4] whereas the other suggests that it is due to slippage between collagen fibrils,[5] with no overall tissue loss. Surgical dissection of the corneal stroma is not resistance-free, even in the posterior region where there is less anterior-posterior interweave, suggesting that there are other elements that bind the collagen lamellae together.[6]Part of this resistance. is due to interactions between the collagen Þ brils (e.g., Type III and heteromeric Type I and V collagens) and other matrix proteins, such as the proteoglycans,[7,8]and Type VI collagen.[9] |
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In addition, diff erences in keratocyte surface components, cell morphology and cell-matrix interactions have all been reported in keratoconus.[10,11] If this “interÞ brillar glue” were weakened,then lamellae (or collagen bundles) would have the potential
to tear apart.[5] The central and inferior regions of the cornea are likely to be aff ected preferentially (the main region of
cone formation), since interlamellar cohesive strength is at a minimum in that area in normal corneas.[12,13] The technique of corneal collagen cross-linking has beenused to at least temporarily block progression of keratoconus
in the progressive phase.[14] Cross-linking ‘freezes’, that is, it arrests the further progression of the corneal collagen thinning /
redistribution that is otherwise progressive in keratoconus stromal collagen, increasing the biomechanical stability of the cornea.[15] The technique of corneal collagen cross-linking consists of photopolymerization of stromal Þ bers by the combined action of a photosensitizing substance (riboß avin or vitamin B2) and ultraviolet A rays (UVA) from a solid-state UVA source.[14] Photopolymerization increases the rigidity of corneal collagen and its resistance to keratectasia.[16] The cross-linking eff ect is not distributed homogenously over the corneal depth. Thestiff ening eff ect is concentrated in the anterior 200 to 300 microns of the cornea due to the high absorption of UV light in this area.[16] The aim of this retrospective nonrandomized open study was to show the results of riboß avin UVA-induced corneal collagen cross-linking in an Indian cohort of patients aff ected by progressive keratoconus, aft er one year of follow-up. To our knowledge, this is the Þ rst retrospective nonrandomized open label study from the Indian subcontinent. |
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original article Clear Vision Eye Centre provides treatment of cornea disease by human donor cornea, keratoplasty, cornea transplantation, keratoconus, corneal edema and corneal transplant surgery in Mumbai, India. |
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