Showing papers on "Vitreous Detachment published in 2004"

Anomalous posterior vitreous detachment: a unifying concept in vitreo-retinal disease

Abstract: Posterior vitreous detachment (PVD) is the consequence of changes in the macromolecular structure of gel vitreous that result in liquefaction, concurrent with alterations in the extracellular matrix at the vitreo-retinal interface that allow the posterior vitreous cortex to detach from the internal limiting lamina of the retina. Gel liquefaction that exceeds the degree of vitreo-retinal dehiscence results in anomalous PVD (APVD). APVD varies in its clinical manifestations depending upon where in the fundus vitreo-retinal adhesion is strongest. At the periphery, APVD results in retinal tears and detachments. In the macula, APVD causes vitreo-macular traction syndrome, results in vitreoschisis with macular pucker or macular holes, or contributes to some cases of diabetic macular edema. At the optic disc and retina, APVD causes vitreo-papillary traction and promotes retinal and optic disc neovascularization. Unifying the spectrum of vitreo-retinal diseases into the conceptual framework of APVD underscores that to more effectively treat, and ultimately prevent, these disorders it is necessary to replicate the two components of an innocuous PVD, i.e., gel liquefaction and vitreo-retinal dehiscence. Pharmacologic vitreolysis is designed to mitigate against APVD by chemically breaking down vitreous macromolecules and weakening vitreo-retinal adhesion to safely detach the posterior vitreous cortex. This would not only facilitate surgery, but if performed early in the natural history of disease, it should prevent progressive disease.

Posterior vitreous detachment induced by microplasmin.

Abstract: PURPOSE. To demonstrate the efficacy of microplasmin in inducing posterior vitreous detachment (PVD) and to evaluate the human and the feline retina after treatment. METHODS. Thirteen human donor eyes were injected with 62.5, 125, or 188 g microplasmin. The 13 fellow eyes received balanced salt solution. Four of the microplasmin-treated eyes received an additional intravitreal gas injection. After incubation at 37°C for 30 minutes, all globes were placed in 4% paraformaldehyde. Retinal specimens were processed for scanning (SEM) and transmission (TEM) electron microscopy. Five feline eyes were injected with 14.5- or 25-g microplasmin. Animals were killed after 1 day, 3 days, or 3 weeks, and retinal specimens were evaluated by electron and confocal microscopy. RESULTS. In all control eyes, SEM demonstrated the cortical vitreous covering the inner limiting membrane (ILM). Intravitreal injection of 125 or 188 g microplasmin resulted in complete PVD. After treatment with 62.5 g microplasmin, SEM revealed collagen fibrils covering the ILM. Additional gas injection did not change the dose necessary for PVD. In vivo in cats, 25 g microplasmin resulted in complete PVD after 3 days. After 3 weeks, there was complete PVD with both doses of microplasmin. The retina and the ILM were well preserved in all eyes. CONCLUSIONS. Both after death and in vivo, microplasmin induces a dose-dependent cleavage between the vitreous cortex and the ILM without morphologic alterations of the retina. In the feline eye, there is no cellular response of retinal glial cells or neurons. (Invest Ophthalmol Vis Sci. 2004;45:641‐ 647)

Unsuccessful vitrectomy without gas tamponade for macular retinal detachment and retinoschisis without optic disc pit.

Abstract: The mechanism of subretinal fluid accumulation in optic disc pit maculopathy is unknown. A 67-year-old Japanese woman complaining of blurred vision in her right eye presented with a best-corrected visual acuity of 20/200. Slit-lamp biomicroscopy and optical coherence tomography examination showed maculopathy typically associated with optic disc pits, except that the patient had no optic disc pit. Long-acting gas tamponade was required to achieve reattachment of the retina and retinoschisis after initial failure of surgery using surgically induced vitreous detachment without either fluid-air exchange or gas injection. Vitreous traction may not have played a major role in introducing fluid into the submacular space in this case. Gas tamponade may be indispensable to achieve surgical success. This may also pertain to some cases of optic nerve pits.

Experimental induction of posterior vitreous detachment in rabbits with hyaluronidase and perfluoroethane (C2F6)

Abstract: OBJECTIVE To evaluate the experimental induction of posterior vitreous detachment (PVD) by intravitreous injection of hyaluronidase and perfluoroethane (C(2)F(6)). METHODS Fifteen rabbits (30 eyes) were divided into 3 experimental groups,the contralateral eyes in same animals served as the controls. Eyes in group A and B were received two vitreous injections of 15 IU of hyaluronidase at an interval of 5 d. The eyes in group C and all control eyes were injected with balanced salt solution (BSS). Seven days after injection, the experimental eyes in group A and C were received 0.5 ml of Fifteen rabbits (30 eyes) were divided into 3 experimental groups, the contralateral eyes in same animals served as the controls. Eyes in group A and B were received two vitreous injections of 15 IU of hyaluronidase at an interval of 5 d. The eyes in group C and all control eyes were injected with balanced salt solution (BSS). Seven days after injection,the experimental eyes in group A and C were received 0.5 ml of C(2)F(6) injection. The ocular and retinal signs were examined for 8 following weeks and then killed for histological examination. RESULT Five eyes in group A (100.0%) showed complete separation of the vitreous cortex from the retina (PVD), three eyes in group B(60.0%) showed partial PVD, and no PVD was detected in group C and all control eyes. On electroretinogram no significant difference was found in amplitude and latency of a-(or b-) wave in both experimental and control eyes, between before and after experiments. No evidence of ocular or retinal toxicity was revealed by light or scanning electronic microscopy in all eyes. CONCLUSION Vitreous injection of hyaluronidase combined with perfluoroethane, as a safety method, can induce posterior vitreous detachment without mechanical vitrectomy.