Investigative ophthalmology最新文献

The effect of phacoemulsification, with the Cavitron-Kelman instrument, on the corneal endothelium of rabbit and cats was studied by scanning electron microscopy and nitroblue tetrazolium staining. The various steps of the procedure were examined separately. Irrigation of the anterior chamber of the eye with balanced salt solution (Plasma-Lyte) for ten minutes caused no cell damage. Ultrasound and irrigation alone for four to six minutes caused increased permeability to NBT. Edema of endothelial cells and cell junction disruption occurred after eight minutes of anterior chamber irrigation with Plasma-Lyte. Uncomplicated phacoemulsification produced moderate cellular edema with scattered loss of endothelial cells. Destruction of endothelial cells was frequent after phacoemulsification, it appeared to be due to lens nucleus manipulation in the anterior chamber, instrumentation, and needle contact. From two to five days postoperatively, intercellular edema, altered cell morphology, and mosaic pattern were seen. However, it gradually recovered and seven to ten days later the endothelium appeared normal.

The uptake in vitro of radioactively labeled test substances was studied in tissues from albino rabbits. Choroid plexus, slices of outer renal cortex, and iris-ciliary body were incubated in a K-rich medium containing one of the cations 14C-Emepronium (Cetiprin), 14C-tetraethylammonium, 14C-choline, or 125I-o-iodobenzyltrimethylammonium and sometimes the anions 131I-o-iodohippurate and 125I-iodipamide. Choroid plexus and renal cortex accumulated all test substances, some to very high tissue-medium ratios. The iris-ciliary body preparation accumulated the anions well but the organic cations only weakly. The only convincing uptake was that of Emepronium. The affinity of this uptake system seemed to be similar to that in the kidney, half-saturating around 10(-4)M Emepronium.

Rat mouse, and chick lenses incubated with 3-aminotriazole under long-wave ultraviolet (UV) show reduced accumulation and incorporation of leucine and a loss of glutathione. The effect on leucine incorporation is strikingly enhanced when capsule-epithelium pools are incubated. The procedure may identify photosensitizers or metabolic inhibitors which are cataractogenic when acting in conjunction with UV.

Some characteristics of children with xerophthalmia are described and the difference in age between those with serious corneal xerophthalmia and those showing milder conjunctival xerophthalmia is noted. The various public health measures instituted to prevent xerophthalmia are examined. The particular importance of protein in food given to severely malnourished children suffering from xerophthalmia is stressed and studies on enzyme activities which are enhanced in the xerophthalmic cornea are briefly noted.

The transfer coefficients of fluorescein in the anterior chamber by flow, kfa, and by diffusion, kdpa, can be calculated for an individual human eye, through an analysis of fluorescein concentrations in the anterior chamber, pupillary aqueous, and serum ultrafiltrates following intravenous injection. Using this technique, aqueous humor dynamics was studied in eight patients with glaucomato-cyclitic crisis. In seven patients, the coefficients determined during the attacks averaged 1.23 +/- 0.08 (S.E.M.) X 10(-2) min.-1 for kfa and 3.51 +/- 0.81 X 10(-3) min.-1 for kdpa in the involved eye, and 0.91 +/- 0.12 X 10(-2) min.-1 for kfa and 1.36 +/- 0.39 X 10(-3) min.-1 for kdpa in the fellow eye. The differences in the coefficients between the two eyes were statistically significant (P less than 0.05). In six patients, the coefficients were measured during the remission, giving average values of 0.81 +/- 0.08 X 10(-2) min.-1 for kfa and 1.36 +/- 0.16 X 10(-3) min.-1 for kdpa in the involved eye, and 0.78 +/- 0.07 X 10(-2) min.-1 for kfa and 1.20 +/- 0.10 X 10(-3) min.-1 for kdpa in the fellow eye. The differences in the coeficients between the two eyes were not significant. In five patients, the determinations were repeated during the attack and remission, and the differences in the coefficients between both phases were statistically significant (P less than 0.05) in the involved eye.

The presence of a dopamine-specific receptor that can influence intraocular pressure in the rabbit eye is suggested by these experiments: intravitreal, systemic, or topically administered dopamine solutions can produce a decrease in intraocular pressure that is dose-dependent. In high doses the decrease in intraocular pressure is accompanied by mydriasis, and alpha-adrenergic pupillary response. This alpha-response may be caused by dopamine as a direct, but weak alpha-stimulator or by displacement of norepinephrine onto the receptor from its storage site. At lower doses the decrease in intraocular pressure occurs in the absence of mydriasis and in spite of blockade of beta-adrenergic receptors. Further, a specific dopaminergic blocker, haloperidol, prevents this decrease in intraocular pressure. The decreases are small, but reproducible and suggest that dopamine can influence the adrenergic regulation of intraocular pressure.

The growth curve of the lens of the Nakano mouse was compared to that of the normal mouse. There was no obvious difference for the first two weeks of age. After this period the growth of the normal lens continued while that of Nakano mouse lens slowed abruptly and eventually ceased. Studies with labeled leucine, however, showed that even after the appearance of the "pin-head" opacity the protein synthesis, although depressed, continued. These findings combined with previous histological observations suggest that new fiber formation is probably unaffected in the early stages of the Nakano cataract. The apparent cessation of lens growth is probably associated with the extensive liquefaction that is observed to occur at the posterior nuclear region.

In every type of beginning senile cataract the cortex of the lens measured with the slit lamp appears thinner than the normal lens cortex in the same age group. The decreased rate of fiber formation and of proteosynthesis precedes the first appearance of lens opacities.

The concentration of drug necessary to inhibit lymphocyte transformation by 50 per cent (I50 value) was determined for the glucocorticoid prednisolone-21-phosphate, and for the sodium-potassium adenosinetriphosphatase inhibitor ouabain, in 37 persons representing the full range of ocular and cellular glucocorticoid sensitivity. The lymphocytes of patients with primary open-angle glaucoma, and of high ocular responders to glucocorticoids, were more sensitive to prednisolone-21-phosphate than were those of ocular low and intermediate responders. By contrast, there was no significant difference in sensitivity to ouabain. There was also no significant correlation of lymphocyte sensitivity to prednisolone-21-phosphate with that to ouabain. These results provide indirect evidence that the increased cellular sensitivity to glucocorticoids in primary open-angle glaucoma is a specific effect, and not merely representative of a general vulnerability of "sick cells."