Repair of outer blood-retinal barrier after severe ocular blunt trauma in rabbits

Localized vitreous adhesion to the retina after ocular contusion with a baseball

Purpose

To report a series of five cases of vitreous adhesions after blunt trauma caused by a baseball strike.

Methods

The medical records of patients with ocular contusion after being struck by a baseball, who had undergone pars plana vitrectomy, were reviewed. An aqueous suspension of triamcinolone acetonide was used intraoperatively to facilitate visualization of the vitreous.

Results

Five eyes were reviewed in this study. There were two cases of retinal detachment, two cases of traumatic macular hole, and one case of retinal detachment due to traumatic macular hole. Despite the surgical creation of posterior vitreous detachment, if not already present, the thin layer of localized vitreous adhesion to the retinal necrotic area with/without retinal hole was found between the major vascular arcades and the equator in all cases. The thin layer of the vitreous was removed with a vitreous cutter and diamond-dusted membrane scraper, but complete removal was impossible.

Conclusions

A thin layer of localized vitreous adhesion at the area of retinal degeneration was observed in eyes following ocular contusion.

FKBP8 is a negative regulator of mouse sonic hedgehog signaling in neural tissues

Sonic hedgehog (SHH) is a secreted morphogen that regulates the patterning and growth of many tissues in the developing mouse embryo, including the central nervous system (CNS). We show that a member of the FK506-binding protein family, FKBP8, is an essential antagonist of SHH signaling in CNS development. Loss of FKBP8 causes ectopic and ligand-independent activation of the Shh pathway, leading to expansion of ventral cell fates in the posterior neural tube and suppression of eye development. Although it is expressed broadly, FKBP8 is required to antagonize SHH signaling primarily in neural tissues, suggesting that hedgehog signal transduction is subject to cell-type specific modulation during mammalian development.

The effect of intraoperative retinal manipulation on the underlying retinal pigment epithelium: an experimental study

PURPOSE

Retinal pigment epithelial changes described after vitreoretinal surgery may result from localized compression injury caused by intentional or inadvertent contact with vitreoretinal instruments. The authors evaluated these changes resulting from manipulation of the retina without frank retinal injury.

METHODS

One eye each of six pigmented rabbits underwent surgery during which the inner retinal surface was touched at several points with a 20-gauge silicone-tipped subretinal fluid cannula without causing a retinal break or subretinal hemorrhage. The rabbits were followed-up with indirect ophthalmoscopy, fundus photography, and fluorescein angiography, and were killed at 1 hour, 1 week, or 2 weeks. Light microscopy was used for histopathologic evaluation.

RESULTS

On fluorescein angiography, diffuse leakage noted at the injury sites significantly decreased by the fourth day and almost completely disappeared by the second week. Disruption of photoreceptor outer segments and retinal pigment epithelium in the early specimens, and irregular pigmentation, proliferation, and migration of the retinal pigment epithelium at 1 and 2 weeks were the prominent features on histopathologic examination.

CONCLUSIONS

Intraoperative manipulation of the attached retina may cause significant pigment epithelium displacement and proliferation and varying degrees of disorganization of normal retinal architecture in the absence of clinically evident retinal breaks and subretinal hemorrhages.

Vascular leakage stimulates phenotype alteration in ocular cells, contributing to the pathology of proliferative vitreoretinopathy

Plasma leaking from damaged retinal blood vessels can have a significant impact on the pathologies of the posterior segment of the eye. Inflammation in the eye and metabolic change resulting from diabetes mellitus causes vascular leakage with alteration of the phenotype of retinal pigment epithelial (RPE) cells and fibrocytes, resulting in changes in cell function. Phenotypically altered cells then significantly contribute to the pathogenesis of retinopathies by being incorporated into tractional membranes in the vitreous, where they secrete matrix molecules, such as fibronectin, and express altered cell surface antigens. We hypothesize that there is a direct relationship between the leaking of plasma and the proliferation and phenotypic change of RPE cells and fibroblasts, thus exacerbating the pathology of retinal disease. If the hypothesis is correct, control of vascular leakage becomes an important target of therapy in proliferative vitreoretinopathy.