Perfluoro-octane in the treatment of giant retinal tears with proliferative vitreoretinopathy.

Giant retinal tears complicated by proliferative vitreoretinopathy (PVR) pose one of the more complex problems in vitreoretinal surgery. The authors developed a technique using perfluoro-octane, a temporary vitreous substitute that is heavier than water, combined with vitrectomy, scleral buckling, fluid-gas exchange, and direct manipulation of the retina to treat these cases. Ten eyes with giant retinal tears and grade D-1 PVR or worse were treated.

Noradrenergic control of ocular dominance plasticity in the visual cortex of dark-reared cats.

In the visual cortex of cats which had been dark-reared for several months since the time before natural eye opening, a cortical infusion of 6-hydroxydopamine (6-OHDA), a noradrenaline (NA)-related neurotoxin, partially suppressed a usual shift in ocular dominance following brief monocular lid suture, causing a significant loss of binocular cells. This partial shift in ocular dominance (U-shaped histogram) was also observed typically in the control hemisphere of cats which were subjected to dark-rearing for more than a year. Furthermore, the expected shift in ocular dominance following monocular deprivation was blocked by a direct cortical infusion of D,L-metoprolol, a selective beta 1-adrenergic receptor antagonist.

Enhanced binocular interaction in the visual cortex of normal kittens subjected to intracortical norepinephrine perfusion.

It was previously proposed that norepinephrine (NE)-containing nerve terminals in visual cortex are important for the maintenance of cortical plasticity. Observations at that time indicated that local microperfusion of exogenous NE for 1 week directly into kitten visual cortex, with no alteration of the visual environment, resulted in an unexpected bias in ocular dominance toward the contralateral eye. The proportion of binocular cells, however, remained close to normal.

Changes in geniculate cell size following brief monocular blockade of retinal activity in kittens.

When a kitten is subjected to monocular lid suture early in life, cells in laminae of the lateral geniculate nucleus (LGN) connected to the sutured eye grow less than normal and cells in those laminae connected to the non-sutured eye grow more than normal. These changes are seen primarily in the binocular segment of the LGN, which corresponds to the central visual field, and are due to competition either between intracortical afferents originating from the different LGN laminae, or directly among cells within the LGN. The afferent deprivation induced by lid suture, however, is not complete, as retinal ganglion cells fire tonically both in darkness and in light.