Investigative ophthalmology最新文献

6-Aminohexanoic acid is a potent antifibrinolytic agent with the ability to retard dissolution of fibrin clots. The corneal penetration of 6-aminohexanoic acid was measured to determine if therapeutic levels of the drug could be maintained in the anterior chamber by topical administration. The conjunctival sac to anterior chamber transfer coefficient was found to be 1.51 X 10-4 +/- 0.20 X 10-4 per minute and the corneal permeability found to be 3.46 X 10-7 +/- 0.46 X 10-7 cm. per second in the rhesus monkey eye. The results indicate that, to establish a therapeutic level in the aqueous humor, a high concentration of drug would have to be used with topical drop administration or a zero order delivery system must be used.

Rat lenses incubated in hypotonic medium adapted to the medium by first undergoing osmotic swelling and then returning after 1 to 2 days to their originial volume. Two processes--osmotic swelling and volume regulation--appear to be working simultaneously. The former is indicated by a decrease in the concentration of cell potassium to the expected level and the latter by a limitation of lens volume associated with a decrease in the potassium content of the lens. These findings are consistent with those observed in other types of cells and may be of significance in understanding the etiology of cataracts.

Rabbits injected intravitreally with bovine gamma globulin (BGG) into the right eyes were challenged 3 months later by an intravitreal injection of ovalbumin (OA) into the left eyes. The rabbits were killed 6, 7, and 9 days after challenge and the number of cells producing antibody to both OA and BGG were enumerated. The uveal tract cells of all left eyes produced anti-BGG even though no BGG had been injected into the left eyes. The uveal tract response to OA was less pronounced and typical of a primary response. High anti-BGG titers were found in the aqueous and vitreous humors of the left eyes of many of the rabbits. The reasons for this apparently non-specific stimulation of a secondary response in the absence of specific antigenic challenge are discussed.

The intraocular pressure of conscious, unsedated owl monkeys (Aotus trivirgatus) was measured with an applanation tonometer. Untreated eyes of the conscious animals were found to have higher values than those reported for owl monkeys anesthetized with pentobarbitone. Locally applied pilocarpine, carbachol, and oxotremorine gave concentration-related reduction in pressure, oxotremorine being the most potent and having longer duration of effect than the other compounds. Slight reductions were also observed with aceclidine and R. S. 86. These results are discussed in relation to the effects of miotics in man.

An ab-interno goniotomy-like operation for disinserting the ciliary muscle from the scleral spur in cynomolgus monkeys is described. Following postoperative miotic and corticosteroid treatment, the eyes did well clinically and the muscle reattached to the sclera posterior to the spur. Outflow facility and intraocular pressure were mildly reduced. There was drainage of aqueous humor via the conventional outflow routes, and blood flow to the ciliary body. The outflow facility increasing effect of intravenous and intracameral pilocarpine was nearly completely eliminated. These and other data suggest that: (1) the ciliary muscle was permanently disconnected, anatomically and functionally, from the trabecular meshwork; (2) the trabecular meshwork and Schlemm's canal remained relatively normal structurally and functionally; (3) monkey eyes with retrodisplaced ciliary muscles may prove valuable for testing the functional effects of drugs directly on the conventional outflow channels, independent of drug actions on the ciliary muscle.

The development of the primate retinal vasculature has been investigated in fetal monkeys (M. mulatta) during the latter half of gestation. Vascularization is found to be retarded in the region of the macula. The macula is found to become completely encircled by a network of primitive capillaries which then proliferate centripetally towards the presumptive fovea. These encircling vessels normally cease to proliferate before reaching the center of the fovea, and the resulting central avascular zone and centripetal pattern of vessels persist thereafter in the mature macula. The superficial peripapillary network of capillaries, like the outer vascular net, is found to be derived from the inner network of vessels.

In a total of 92 eyes in 46 individuals the outflow facilities obtained by weight tonography, Cton correlated curvilinearly with those estimated by an acetazolamide test, Cacet. The presumed apathological pairs of eyes were those with Cacet above (or equal to) 0.15 and pressure symmetry (right/left). Twenty-one patients referred for glaucoma suspicion (and three normal test persons) showed these characteristics. The eyes appeared clinically healthy even if the pressure range reached 30 mm. Hg. Here Cacet averaged 0.32 but Cton only 0.16; the discrepancy is possibly caused by the outflow obstruction brought about by the high pressures during weight tonography. The presumed pathological eyes (33 from 20 individuals referred for glaucoma suspicion or manifest glaucoma) were those with Cacet below 0.15. They generally showed pressure asymmetry and in some cases pressure values above 30 mm. Hg, and there were in several cases other glaucomatous signs. In this group Cton and Cacet were similar; both averaged 0.09. The acetazolamide test is considered more informative than weight tonography because the test provides at the same time an estimate of the outflow facilities in the normal- or low-pressure range as well as an accurate comparison between the pressures and outflow facilities of the two eyes. The test is time-consuming, however (1 to 11/2 hours).

To determine whether the absence of pituitary or ovarian hormones would influence retinal degeneration, female albino rats were either hypophysectomized (HYPEX) or ovariectomized (OVEX) before pubery. Later, they were exposed to continuous light for periods up to 45 days. Retinas evaluated by light microscopic measurements showed damage to the outer nuclear layer (ONL) and photoreceptor layer in both the operated and intact, control rats. However, the degree of damage observed in retinas of HYPEX and OVEX rats was significantly less than that observed in retinas of intact rats exposed to the same lighting conditions. Therefore, hypophysectomy and ovariectomy, which influence the normal development of sexual maturation when performed on immature rats, significantly reduce photoreceptor damage in adult rats exposed to continuous light.

Dose-response curves of increase in pupil size and decrease in intraocular pressure with topical epinephrine have been determined in the sympathetically denervated rabbit eye. Topical pretreatment with the catechol-O-methyl transferase inhibitor U-0521 potentiated the effects of epinephrine on both the pupil and pressure. These observations suggest a possible role for catechol-O-methyl transferase in the aqueous humor dynamics of the supersensitive eye. The possible use of the denervated rabbit eye as an experimental model for the glaucomatous eye in evaluating the ocular effects of adrenergic agents is discussed.

The ionophores A23187 and X537A, which increase the permeability of cell membranes to calcium and other divalent cations, produced significant elevation of intraocular pressure in rabbits. Topical instillation of these ionophores in concentrations of 1.0 and 0.1 per cent were effective. Aqueous humor protein and facility of outflow were similar in ionophore-treated and control eyes. Pretreatment with indomethacin did not block the intraocular pressure rise induced by A23187. Alterations of intracellular calcium might control cellular processes within the eye as in many other biological systems.