Clinical, Refractive and Histological Reversibility of Corneal Additive Surgery in Deep Stroma in an Animal Model

Abstract

Purpose: The aim was to evaluate the reversibility of the clinical and histological changes induced in the corneas of an animal model after removing an intracorneal ring segment (ICRS). Methods: Surgery for this study was performed in 38 eyes of an experimental animal model (Gallus domesticus) for ICRS surgery (Ferrara technique). The animals without complications were randomized to two groups; in all of them, 1 segment was implanted in each eye and later removed at different times (1 and 3 months after implantation). In each group, after explantation, corneas were processed at different times for histological analysis with hematoxylin and eosin (H&E) stain and electronic microscopy. The refractive state of the eyes was also measured. Results: In corneas without complications (88.23%), explantation was performed correctly. During the first few days, around the area where the ICRS was implanted we observed deposits of cells and a moderate degree of corneal opacity (haze). These signs decreased progressively without disappearing completely. Histologically, at 7 days, we observed hyperplasia and abnormal arrangement of collagen fibers. Later, these findings also decreased in both groups, albeit at a faster rate in group 1. Minimal changes were observed in electron microscopy up to the end of the study in both groups. Preoperative refractive state was achieved at 1 month after explantation in both groups. Conclusions: ICRS can safely be explanted from the cornea. Refractive reversibility was achieved at 1 month after explantation. However, the clinical and histological findings after ICRS explantation depend on the time from implantation to explantation. ARTICLE HISTORY

Evaluation of a new nomogram for Ferrara ring segment implantation in keratoconus

“…Ferrara-type ring segments have been investigated during many years and demonstrated to be a safe option to manage corneal irregularities in a great variety of corneal conditions, including keratoconus [14][15][16][17][18][19][20][21][22][23][24] . It has been even confirmed the histological reversibility of the cornea when the ring segments are explanted [25] . Initially, most of case series evaluating the outcomes with this type of implants were empirical, using refraction and keratometry as key factors for the selection of the ring segments to implant in each case [26][27][28] .…”

ByLimb: Development of a New Technique to Implant Intracorneal Ring-Segments from the Perilimbal Region

“…Although the clinical aspect of immediate corneal healing seems to be optimal and no complications have been found in 17 operated eyes, the long-term safety of this technique is currently being evaluated in a pilot study with a 1-year follow-up in the eyes of keratoconus patients implanted with Ferrara ICRS. It would also be interesting to have studies on animal models in order to better understand aspects of corneal healing in relation to the effect of femtosecond laser in the perilimbal area described in this work, as well as to know the intrastromal reaction of ICRS implanted by this technique and its reversibility, as previously studied with the traditional technique by Ibares-Frías et al [ 11 , 12 ].…”

Comparative Histology of the Cornea and Palisades of Vogt in the Different Wild Ruminants (Bovidae, Camelidae, Cervidae, Giraffidae, Tragulidae)

“…The cornea is primarily a protective eye (resistance against external hazards) but also plays an important role in the optical system of the eye, which is primarily influenced by its transparency as well as its ability to refract and focus light rays. Most of the research on the structure and function of the cornea to create more and more perfect methods of treating the diseases of the cornea itself is most often conducted on laboratory animals (mice, rats, rabbits, and hens) which are animal models for human resources [ 36 , 37 , 38 , 39 , 40 , 41 ]. Corneal morphology studies in domestic animals, such as dogs, cats, equine, porcine, cows, goats or sheep, which also become animal models [ 3 , 12 , 17 , 42 , 43 , 44 , 45 , 46 , 47 ].…”