• shape
  • Such a lens does not provide an adequate meansof even closely conforming to the shape of the cornea because there can be no spherical surface constructed slightly greater than the radius of curvature of the cornea to which it is applied that will do anything but set up a gradient of pressure on the cornea with a maximum pressure at the apex and a minimum towards the ed-ge. (google.com)
  • attempt
  • By a series of auxiliar-y bevels or secondary surfaces these areas are `ground away in an attempt to obtainthe best approximate `fit of the cornea. (google.com)
  • either
  • l) Such a small lens nearly always causes lid `irritation in blinking due to the fact that the margin of the lids contains the greatest concentration of nerve endings and, (2) such lenses lslip readily due to lid action and will either be displaced off the cornea or fall out of the eye. (google.com)
  • surface
  • To be more specic, according to conventional practice, in -order to make the inner surface of the lens compatible to the cornea, the lens is rst reduced in diameter to as small a size as possible for the purpose of using the .central optic zone of about 6 to 7 mm. in diameter as a bearing surface for the lens. (google.com)
  • devices
  • Conventional pachymeters are devices that display the thickness of the cornea, usually in micrometres, when the ultrasonic transducer touches the cornea. (wikipedia.org)
  • The ultrasonic Pachymeters traditionally have been devices that provide the thickness of the human cornea in the form of a number in micrometres that is displayed to the user. (wikipedia.org)