AN EYESIGHT ANOMALY.

Pukekohe & Waiuku Times, Volume 6, Issue 251, 16 February 1917, Page 4 (Supplement)

AN EYESIGHT ANOMALY.

Str.-.nge as it may >e;'in, few of t!is twf-cyi.'j animals have tre binocular vKi-'.n. A 1 tt of tlieu, have their eyes situated on the two opposite sides of their heads, so that they look in opposite directions; and, while it is true th it by retison of the sweep Ot their vision, they can see not only to the and left, but more or l<ss to the front and rear, it a!s> trie that in < rde.- to Let a keener view of what is before, an animal will often tnin its lead, directing one eye toward the object of its contemplation. It must be t: at it centres its attention upon what tho directed eye is seeing, and ignores what the other eye beholds. And doubtless tho same tiling is done even when the head is held naturally. Here are seen objects to left and right; the attention may bo directed to either the ono er the other. Xow (says a writer in the "S icntifie A men an") a U this is inoiiPMilar vision, in spito of the fa<• t. that two eyes are open and seeing: it is only one eye that, is engaging tho attention.

A very few cf the lower animals, I ke :-om? ol tho monkeys, .seem to possess the true binocular vision—that is, they centre both eyes on the same object as tile same liri.e, and blend the two imago, into one. The dog is not one <>.' lin spite of the forward position of it-, eyes; it is but a single eye that the dog centres upon the o'jovt of iiiteiest. Man, on the other hand, possessing a well-developed faculty of both eyes upon the same object willi successful results, probably leads tho entire procession in the matter of binocular vision.

Sola 1 : Iniiovo t!>at, in tlio evolution ot life, hinrcular vis on is a recently acquired faculty cn the pnrt nf man, and they pcint to its imperfection* 'as indicative of it.; rc:ent origin: it lias not yet had time to attain its full development. for tlie! o exist more in;perfections in binocular seeing than n:o>t p«H)p!o suppose. Ocoulists are finding that a considerable percentage of mankind do not habitually u-e binocular vision. \\ liile they have two ayes, they sco consciously with hut o"e. Only ona eyo at a lim.s ia concentrated upon the o!'jp"t t(j ho observed : the other looks ii i it may. T.ke the r;fF eve of the loire- animal, its impressions are ignored by tin mind. This is trie not r.n'y of peoplo whoso eyes are divergent or walled; in many cases where tlio eyes nre normally forward. one of tile two organs shirks duty, cither constantly or hy alternation with the other.