Most detachments, unless bilateral, are usually subclinical and manifest with only mild pupillary dilation, until they have been present for several months when they manifest with uveitis and hyphema, when hyperoxia is of limited use. However, rapid reattachment (24–48 h) and the provision of hyperoxia for domestic animals with detached retinas will not likely be available in the clinical setting in the near future. In addition, hyperoxia early in the course of retinal detachment has a predictable clinical benefit by increasing O 2 diffusion to the detached retina ( 10– 13). Rapid reattachment within 24 h arrests and even reverses some of these cellular events ( 9). Then, a progressive degeneration of the inner and outer segments of the photoreceptors occurs, followed by loss of the outer plexiform layer eventually, the inner nuclear and inner plexiform layers also degenerate ( 7). This process occurs by mitochondrial dependent pathways ( 8). Apoptosis is the key cellular event that occurs rapidly (within 3 d of detachment) and results in a permanent depletion of postmitotic outer nuclear cells ( 8). When photoreceptors are separated from the retinal pigment epithelium, the outer and inner segments of the rods and cones degenerate quite rapidly and the retinal pigment epithelium hypertrophies ( 7). When the detachment is chronic, hyphema and uveitis are common sequelae, due to the development of pre-iridal fibrovascular membranes ( 4– 6). The blood retinal barriers are easily damaged during retinal detachment, and retinal, subretinal, and vitreous hemorrhage may be present ( 1, 2). After the retina detaches in dogs, the retinal pigment epithelium changes rapidly, with hypertrophy and hyperplasia, and the epithelial cells may detach from their basement membrane and become migrating cells with macrophage-like properties ( 3). However, the pathogenesis always includes 1 or a combination of 3 basic mechanisms: traction detachment due to fibrous strands within the vitreous retinal tears or holes with leakage of vitreous into the subretinal space or exudation of fluid and inflammatory cells under the retina ( 1, 2). The etiologies of retinal detachment in dogs are diverse. Retinal detachment in dogs may be partial or focal, and not perceptibly affect vision, or it may be complete and the affected eye is blind. Les observations en microscopie optique des globes défectueux des 3 groupes montraient des résultats similaires. Quatre des 6 yeux traités par réattachement chirurgical n’ont pas manifesté d’uvéite clinique ni de glaucome secondaire et 3 de ces yeux avaient une vison fonctionnelle. Quinze des 19 yeux ayant reçu une thérapie topique ont développé une uvéite qui ne répondait pas au traitement et un glaucome secondaire et ont été énucléés ( 4) ou éviscérés ( 9), 1 chien qui était atteint bilatéralement a été euthanasié et 3 yeux sont demeurés sur thérapie anti-inflammatoire topique alors que la médication a été arrêtée sur 1 œil. Deux yeux chez 2 chiens étaient demeurés sans traitement 1 an et 3 ans plus tard. Quatorze des 16 yeux n’ayant pas été traités ont développé une uvéite et un glaucome secondaire : 4 ont été énucléés et 2 chiens ont été euthanasiés à cause de cécité et d’uvéite. Une comparaison de l’évolution du détachement chronique (>1 mois) de la rétine et des déchirures rétiniennes géantes a été réalisée entre animaux non traités et traités avec des stéroïdes topiques et une médication anti-glaucome et traités par vitrectomie, réattachement de la rétine, thérapie au laser et tamponnade à l’huile à la silicone. Light microscopic observations completed on failed globes in the 3 groups were similar.ĭétachement chronique de la rétine et déchirures rétinienne géantes chez 34 chiens : comparaison des résultats des cas non traités, traités par médication topique ou par réattachement de la rétine après vitrectomie. Four of 6 eyes surgically reattached remain without clinical manifestations of uveitis and secondary glaucoma and 3 of these eyes have functional vision. Fifteen of 19 eyes that received topical therapy developed nonresponsive uveitis and secondary glaucoma, and were enucleated ( 4) or eviscerated ( 9), 1 dog that was affected bilaterally was euthanized and 3 eyes remain on topical anti-inflammatory therapy and the medication has been discontinued on 1 eye. Two eyes in 2 dogs remain without treatment, 1 and 3 years later. Fourteen of 16 eyes that did not receive therapy developed uveitis and secondary glaucoma, and were enucleated ( 4) or eviscerated ( 6) and 2 dogs were euthanized due to blindness and uveitis. The outcomes of dog’s eyes with chronic (>1 month) retinal detachment and giant retinal tears without therapy were compared with those treated with topical steroids and antiglaucoma medications, and with those that received a vitrectomy, retinal reattachment, endolaser therapy, and silicone oil tamponade.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |