Clinical and histological effects of the temporary occlusion of the rabbit nasolacrimal duct and point using cyanoacrylate adhesives

The objective of this study was to evaluate the clinical and histological effects of occluding the nasolacrimal ducts and points of rabbits. For this study, 20 adult New Zealand rabbits, both males and females, weighing 3.2±0.4kg were allocated into two groups for n-butyl-cyanoacrylate occlusion (GB, n=10) or 2-octyl-cyanoacrylate occlusion (GO, n=10). The contralateral eyes served as the controls. The persistence of tears was evaluated daily using the Schirmer I test. Discomfort, eye discharge, epiphora, and conjunctival hyperemia were assessed prior to the procedure (T0) and during the 14 subsequent days (T1-T14). On days seven and 14, five animals from each group were euthanized, and their nasolacrimal ducts were collected, processed and analyzed by histology. In the GB group, the Schirmer test values differed from that at T0 at all of the subsequent time points, whereas there was no difference in the values observed from the GO group. Compared with the corresponding controls, the GO and GB groups differed significantly at almost all of the time points. When comparing the treatment groups, differences were found at T6, T7, T9, T10, T11, T12 and T14, with higher Schirmer values in the GB group. Epiphora was observed in the GB group from T1 to T8 and in the GO group from T1 to T6. Within seven days post-occlusion, histology revealed a moderate foreign body reaction, with marked necrosis and sloughing of the canalicular epithelium, in the GO group, which was absent at day 14. In the GB group, a marked inflammatory reaction and a mild foreign body reaction were found at day seven, and the foreign body reaction was prevalent at day 14. This study demonstrated that both adhesives were effective in obstructing the nasolacrimal ducts and points of rabbits and that their application and handling are easy and free of complications. However, both adhesives promoted inflammatory and foreign body reactions that evolved to repair and regeneration at day 14 of evaluation

Sclerocorneal limbal stem cell autograft transplantation in dogs

Avaliaram-se os efeitos do transplante de células tronco autógenas do limbo esclerocórneo de cães, sobre lesões córneo-limbais. Empregaram-se 18 cães, distribuídos em dois grupos, GI e GII. Nos animais do GI (n=12), foram realizados transplantes de limbo, após 30 dias da destruição das células tronco-límbicas. Nos do GII (n=6), realizou-se apenas a destruição do limbo (controle). Aos 3, 7, 15, 30, 60 e 120 dias do transplante de limbo (GI) e aos 33, 37, 45, 60, 90 e 150 dias da destruição do limbo (GII), os olhos foram coletados por enucleação subconjuntival, para estudos em microscopia de luz. A destruição do limbo resultou em completa excisão das células tronco, com perda da transparência corneal. O transplante do limbo evitou a conjuntivalização na área em que foi realizado. Os animais do grupo-controle manifestaram conjuntivalização em 360º e vascularização corneal. Na anatomopatologia, em nenhum dos períodos foi possível distinguir o enxerto do epitélio corneal normal. As células caliciformes foram observadas nos animais do GII, nos períodos 33, 37, 60, 150 dias. No GI, apenas um cão manifestou células caliciformes de forma discreta, aos 60 dias do transplante. O transplante autógeno foi eficiente em possibilitar a melhoria da transparência córnea, sem intercorrências oculares.The effects of sclerocorneal limbal stem cell autograft transplantation in dogs with corneal wounds were studied. Eighteen dogs were divided in two groups (GI and GII). The animals of GI (n=12) underwent limbal transplantation 30 days after the destruction of limbal stem cells. The dogs of GII (n=6) only underwent destruction of stem cells (control group). Light microscopy examination of the right eye was performed on days 3, 7, 14, 30, 60, and 120 after limbal transplantation (GI), and on days 33, 37, 44, 60, 90, and 150 after limbal destruction (GII). Results showed a complete destruction of limbal stem cells with loss of corneal transparency. Limbal transplantation prevented conjunctivalization in grafted area. Corneal vascularization and a 360º corneal conjunctivalization were noted in the control dogs (GII). Corneal transparency was restored from day 60th after surgery. Histological examination did not distinguish the transition between the graft and the normal corneal epithelium at anytime. Goblet cells were found in control animals (GII) on 33, 37, 60, and 150 days, whereas a single grafted dog (GI) presented a few goblet cells on day 60th post-transplantation. Limbal autograft transplantation was effective in restoring corneal clarity with no development of ocular complications.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq