Adaptation to disparity but not to perceived depth

The purpose of the present study was to investigate whether adaptation can occur to disparity per se. The adapting stimuli were large random-dot patterns of which the two half-images were transformed such that the depth effects induced by the vertical transformations were nulled by horizontal transformations. Thus, the adapting stimuli were perceptually the same, whereas the disparity fields differed from each other. The adapting stimuli were presented for five minutes. During that period, the percept of a fronto-parallel surface did not change. After the adapting period, subjects perceived a thin untransformed strip as either slanted or curved depending on the adapting transformation. The thin strips provided negligible information about the vertical disparity field. In a forced-choice task we measured the amount of horizontal transformation that was required to null the acquired adaptation. We found that the amounts of horizontal transformation required to perceive the test strip fronto-parallel were significantly different from zero. We conclude that the visual system can adapt to disparity signals in the absence of a perceptual drive.     

Oral epithelial cells transplanted on to corneal surface tend to adapt to the ocular phenotype

To understand the response of oral epithelial cells, transplanted on corneal surface to the ocular cues in vivo. The corneal button obtained after penetrating keratoplasty (PK) of an eye of a patient with total limbal stem cell deficiency (LSCD), previously treated with cultured oral mucosal epithelial transplantation (COMET) was examined by immunohistochemistry for the expression of keratins, p63, p75, PAX6, Ki-67, CD31, and CD34. COMET followed by optical-PK has improved visual acuity to 20/40 and rendered a stable ocular surface. The excised corneal tissue showed the presence of stratified epithelium with vasculatures. The epithelial cells of the corneal button expressed K3, K19, Ki-67, p63, p75 and the cornea-specific PAX6 and K12. This study confirms that the oral cells, transplanted to corneal surface, survive and stably reconstruct the ocular surface. They maintain their stemness at the ectopic site and acquire some of the corneal epithelial-like characters.     

Increased sensitivity to speed changes during adaptation to first-order, but not to second-order motion

Observers adapted to drifting patterns varying either in luminance (first-order pattern), or in contrast (second-order pattern). Sensitivity to increases or decreases in the speed of the first-order pattern increased sharply as adaptation time increased, but sensitivity to speed changes of the second-order pattern remained unchanged throughout the adaptation time. Adaptation of first-order motion mechanisms seems thus to mediate increased sensitivity to variations in speed around the adapting speed. No evidence was found for such effects of adaptation to second-order motion. The observed differences in the effects of adaptation accord well with reports of fundamental differences between after-effects to drifting first- and second-order patterns and are in harmony with models of motion perception emphasizing different mechanisms for the detection of first- and second-order motion.     

Initial approach to the contribution of informatics to strabismology

The authors report the results obtained in 300 cases of strabismus, during one year, on a Computer Apple IIe. The best use of a simple program gave 156 research-keys, each fiche containing 60 keys. The authors pointed the high percentage of premature infants. They insist on the many future epidemiologic possibilities and the potentially better treatment choices.     

The ability of ocular bacteria to bind to fibronectin

Background : Fibronectin enters the tear film during sleep and on reflex tear stimulation. Also, contact lens wearers with increased levels of fibronectin in their tears are more likely to carry greater numbers of bacteria on their contact lenses. This points to a role of fibronectin in mediating adhesion of bacteria to contact lenses. Methods : Bacterial strains isolated from the eyes of contact lens wearers were examined for their ability to bind to fibronectin. Fibronectin binding was examined in solution or adsorbed onto a surface. Results : A strain of Pseudomonas aeruginosa isolated at the time of an acute keratitis and a strain of Stenotrophomonas maltophilia isolated from an asymptomatic eye adhered to soluble or adsorbed fibronectin by greater amounts than other species tested (p < 0.01). Using fibronectin derived from plasma (pFn) and fibronectin derived from cells (cFn) it was shown that the addition of cFn in the presence of pFn increased the binding of pFn to cells indicating aggregation or co-operativity in binding between the two fibronectin types to the cell surface. P. aeruginosa probably bound to both the protein and carbohydrate moieties of fibronectin. Protein(s) on the cell surface of P. aeruginosa probably mediated the adhesion as digestion of cells with protease significantly (p < 0.01) reduced binding. Conclusions : Bacteria isolated from contact lenses, and in particular gram-negative bacteria implicated in the production of keratitis, are able to bind to fibronectin. Also, different types of gram-negative bacteria had distinct abilities to adhere to fibronectin. This may have implications in the binding of these strains to contact lenses in vivo.