Femtosecond-UVA-riboflavin (FUR) cross-linking approach to penetrating keratoplasty and anterior lamellar keratoplasty

Effects of Corneal Stromal Lens Collagen Cross-Linking Regraft on Corneal Biomechanics

Background

Corneal collagen cross-linking (CXL) therapy, a method that uses a combination of riboflavin and ultraviolet-A light (UVA), can promote the formation of covalent cross-linking of amino acid residues of corneal collagen and enhance the hardness of the cornea. In this study, we explored the effects of corneal stromal lens collagen cross-linking regraft on corneal biomechanics.

Methods

A total of 15 New Zealand white rabbits were divided into 3 groups: normal control group (group A), SMILE + uncross-linked lens implantation group (Group B), and SMILE + cross-linking lens implantation group (group C). The design parameters of SMILE surgery were as follows: the corneal cap was 120 um thick, the lens diameter was 6.5 mm, and the diopter was -6.0D. Riboflavin and ultraviolet-A (UVA) were used as corneal stromal lens CXL, which was implanted into the allogeneic rabbit corneal stromal bag 24 hours after the operation. Postoperative corneal thickness (CCT), refraction, AS-OCT, and corneal biomechanics were performed before and then at 1 and 3 months after the operation.

Results

All corneas appeared transparent and smooth 3 months after surgery. The corneal thicknesses of both group B and group C were lower than those before the operation. The corrected refraction of group B and group C after lens implantation was also lower than the expected corrected power; there was no significant difference between the two groups (P > 0.05). AS-OCT results showed an uneven surface and thickness of the corneal stromal lens in two eyes of group B. Moreover, corneal elastic deformation increased with intraocular pressure in each group; displacement from large to small was group B > group C and > group A. The creep from large to small was group B > group C > group A. The fiberboard layers of groups B and C were disordered, and there were a few autophagosomes in the fibroblasts of group B by transmission electron microscopy (TEM).

Conclusions

Allograft graft of corneal stromal lens collagen cross-linked can significantly increase the biomechanical properties of the cornea.

Simultaneous Noncentered Photoactivated Chromophore for Keratitis-Corneal Collagen Cross-Linking and Penetrating Keratoplasty for Treatment of Severe Marginal Fusarium spp. Keratitis: A Description of a New Surgical Technique

The purpose of this article is to describe the use of simultaneous noncentered photoactivated chromophore for keratitis-corneal collagen cross-linking (PACK-CXL) combined with penetrating keratoplasty in the treatment of a severe marginal Fusarium spp. keratitis case with imminent corneal perforation. It is a retrospective case report study; it was performed by collecting clinical data, images, video, and postoperative evaluations. The clinical control of the infection was accomplished, despite difficulties in obtaining antifungal medications due to the patient's extremely poor socioeconomic status and essentially nonexistent health insurance. We can conclude that combining simultaneous decentered PACK-CXL with centered penetrating keratoplasty appears to be a safe and effective way of treating patients with fungal marginal keratitis with corneal perforation, in which regular penetrating keratoplasty alone would leave fungal elements in the receptor corneal tissue, which would predispose to infection of the graft.

Collagen cross-linking as an adjunct for repair of corneal lacerations: a cadaveric study

OBJECTIVE

To determine the efficacy of collagen cross-linking (CXL) as an adjunct to suturing in the repair of corneal lacerations.

METHODS

A cadaveric study was undertaken in which a linear 5 mm corneal laceration was created in the central cornea of 20 eyes. The eyes were then randomized to receive 1 (n = 8), 2 (n = 8), or 3 (n = 4) standard corneal sutures. The burst pressure of the wound was then measured. All eyes in the 1- and 2-suture group then underwent standard CXL, with burst pressure repeated afterward.

RESULTS

The initial wound burst pressure in the 1-, 2-, and 3-suture groups was 54.9, 74.0, and 201.2 mm Hg, respectively. After CXL, wound burst pressure increased by a mean of 3.2 and 62.3 mm Hg in the 1- and 2-suture groups, respectively. This change was statistically significant in the 2-suture group (p = 0.017). After CXL, the 2-suture group still had a significantly lower burst pressure compared with the 3-suture group (p = 0.011).

CONCLUSIONS

The study highlights a potential novel application for CXL to strengthen corneal wounds. Provided that suture density is sufficient to appose the wound edges, CXL may result in short-term wound strengthening. This could potentially allow for decreased corneal suture density and a corresponding decrease in suture-related complications.

Donor cross-linking for keratoplasty: a laboratory evaluation

Purpose

This laboratory-based investigation compares the topographic outcomes of conventional penetrating keratoplasty with that of a novel procedure in which donor corneas are cross-linked prior to keratoplasty.

Methods

Penetrating keratoplasty procedures with continuous running sutures were carried out in a porcine whole globe model. Sixty eyes were randomly paired as ‘donor’ and ‘host’ tissue before being assigned to one of two groups. In the cross-linked group, donor corneas underwent riboflavin/UVA cross-linking prior to being trephined and sutured to untreated hosts. In the conventional keratoplasty group, both host and donor corneas remained untreated prior to keratoplasty. Topographic and corneal wavefront measurements were performed following surgery, and technical aspects of the procedure evaluated.

Results

Mean keratometric astigmatism was significantly lower in the cross-linked donor group at 3.67D (SD 1.8 D), vs. 8.43 D (SD 2.4 D) in the conventional keratoplasty group (p < 0.005). Mean wavefront astigmatism was also significantly reduced in the cross-linked donor group 4.71 D (SD 2.1) vs. 8.29D (SD 3.6) in the conventional keratoplasty group (p < 0.005). Mean RMS higher order aberration was significantly lower in the cross-linked donor group at 1.79 um (SD 0.98), vs. 3.05 um (SD 1.9) in the conventional keratoplasty group (P = 0.02). Qualitative analysis revealed less tissue distortion at the graft-host junction in the cross-linked group.

Conclusion

Cross-linking of donor corneas prior to keratoplasty reduces intraoperative induced astigmatism and aberrations in an animal model. Further studies are indicated to evaluate the implications of this potential modification of keratoplasty surgery.