The effects of riboflavin/ultraviolet: A corneal cross-linking on the signs and symptoms of bullous keratopathy

Abstract

Purpose:To evaluate the effectiveness of corneal cross-linking in improving the signs and symptoms of bullous keratopathy.Materials and Methods:This prospective non-randomized case series evaluated 20 eyes with bullous ketratopathy that underwent corneal cross-linking (C3R) with riboflavin and ultraviolet-A (UVA, 370 nm, 3 mW/cm2). C3R was performed for 30 min in a routine procedure after removal of epithelium. Central corneal thickness (CCT), corneal haze, visual acuity (VA), and the presence of irritating symptoms were recorded before the procedure, and at 1 week, 1 months, 3 months, and 6 months after the procedure.Results:The mean CCT was 872 ± 162 μm (range: 665-1180 μm) before the procedure. Following the procedure, CCT was 855 ± 175 μm after 1 week, 839 ± 210 μm after 1 month, 866 ± 185 μm after 3 months, and 863 ± 177 μm after 6 months (P>0.05, all visits). There was no significant improvement in VA or corneal clarity after 6 months. Improvement of the following symptoms: burning, pain, and foreign body sensation were reported after 6 months by 83.3%, 75.0%, and 66.7% of patients, respectively. Persistent epithelial defect occurred in five patients (25%) resolved with frequent lubrication and bandage contact lenses.Conclusion:The outcomes of this study indicate corneal cross-linking is not an effective treatment for bullous keratopathy with respect to VA and CCT, although it can improve irritation and discomfort.

The Effect of Riboflavin/UVA Collagen Cross-linking Therapy on the Structure and Hydrodynamic Behaviour of the Ungulate and Rabbit Corneal Stroma

“…This could be explained by the existence of indirect cross-linkage between collagen fibrils via their attached proteoglycan core proteins (Figure 8G). Furthermore, comparison of our swelling study with that of Wollensak et al [20] has for the first time produced scientific evidence that may explain why the beneficial effects of improved corneal thickness and transparency seen in riboflavin/UVA cross-linked bullous keratopathy corneas, fade with time [14], [15], [16]. It seems that the transient decrease in stromal thickness following treatment, may be largely attributable to the deturgescent effect of the dextran, which once removed from the tissue allows the osmotic balance of the cornea to be gradually restored.…”

“…The success of riboflavin/UVA cross-linking therapy for the prevention of keratoconus progression has been well documented in recent years [35], [36], however the use of the technique for the treatment of bullous keratopathy (a condition in which the cornea becomes permanently swollen), has failed to produce lasting benefits [14], [15], [16]. In order to form a better understanding of the functionality of riboflavin/UVA cross-linking for the treatment of various corneal disorders and to determine the site at which riboflavin/UVA induced cross-links are formed, we investigated the effects of the treatment on corneal ultrastructure, hydrodynamic behaviour and resistance to enzymatic digestion, The results presented in this study provide the first scientific evidence that may help to explain why riboflavin/UVA cross-linking of bullous keratopathy corneas produces only short-term improvements in corneal thickness and transparency.…”

“…It seems that the transient decrease in stromal thickness following treatment, may be largely attributable to the deturgescent effect of the dextran, which once removed from the tissue allows the osmotic balance of the cornea to be gradually restored. Indeed bullous keratopathy corneas dehydrated with 40% glucose for 24 hour prior to cross-linking produced much longer-lasting reductions in corneal thickness (up to 8 months) [45] than those cross-linked without prior dehydration [14], [15], presumably due to the corneal oedema limiting the penetration of riboflavin (and hence dextran) into the deeper layers of the cornea during the standard cross-linking procedure.…”

“…This has the effect of increasing the biomechanical stability of the cornea [7], [8] and its resistance to enzymatic digestion [9], thereby arresting keratoconus progression. The potential of the technique for the treatment of other corneal disorders such as keratitis [10], [11] and bullous keratopathy [12], [13], [14], [15], [16] is currently being explored.…”

Corneal endothelial cell dysfunction: etiologies and management

“… 88 Other studies have not achieved such good results and found CXL to be ineffective in the management of eyes with corneal edema. 91 , 92 …”