Mindblown: a blog about philosophy.

A contact lens (usually corneal) which is opaque except for a central aperture of 1-2 mm. in diameter; it can be used in presbyopia and in some cases of subnormal vision.  

A half moon shaped contact lens which constitutes the reading add when fitted in conjunction with an ordinary single vision contact lens.  

A keratoscope provided with a camera, used to photograph the keratoscopic pattern reflected from the cornea.  

A photokeratoscope provided with a camera, used to photograph the keratoscopic pattern reflected from the cornea, and having an auxiliary device for use in analyzing the photograph electronically.  

The direction or orientation of one eye with respect to the other, when fusion is interrupted.  

The most peripheral curve on the back surface of a contact lens, usually having a radius of curvature from 9.50 mm. to 12.25 mm., and a width from 0.2 mm. to 0.5 mm.  

The region between the upper and lower eyelid margins within which can be seen, when the lids are open, the eye and adjacent structures. The opening separating the upper and lower eyelids.