566
Opinion of the Court
measures undertaken, whether consciously or not, with the body's own systems.
Finally, and perhaps most significantly, the Court of Appeals did not pay much heed to the statutory obligation to determine the existence of disabilities on a case-by-case basis. The Act expresses that mandate clearly by defining "disability" "with respect to an individual," 42 U. S. C. § 12102(2), and in terms of the impact of an impairment on "such individual," § 12102(2)(A). See Sutton, ante, at 483; cf. 29 CFR pt. 1630, App. § 1630.2( j) (1998) ("The determination of whether an individual has a disability is not necessarily based on the name or diagnosis of the impairment the person has, but rather on the effect of that impairment on the life of the individual"); ibid. ("The determination of whether an individual is substantially limited in a major life activity must be made on a case by case basis"). While some impairments may invariably cause a substantial limitation of a major life activity, cf. Bragdon, supra, at 642 (declining to address whether HIV infection is a per se disability), we cannot say that monocularity does. That category, as we understand it, may embrace a group whose members vary by the degree of visual acuity in the weaker eye, the age at which they suffered their vision loss, the extent of their compensating adjustments in visual techniques, and the ultimate scope of the restrictions on their visual abilities. These variables are not the stuff of a per se rule. While monocularity inevitably leads to some loss of horizontal field of vision and depth perception,12 consequences the Ninth
12 Individuals who can see out of only one eye are unable to perform stereopsis, the process of combining two retinal images into one through which two-eyed individuals gain much of their depth perception, particularly at short distances. At greater distances, stereopsis is relatively less important for depth perception. In their distance vision, monocular individuals are able to compensate for their lack of stereopsis to varying degrees by relying on monocular cues, such as motion parallax, linear perspective, overlay of contours, and distribution of highlights and shadows. See Von Noorden, supra n. 2, at 23-30; App. 300-302.
Page: Index Previous 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 NextLast modified: October 4, 2007