NCLE Preparation Exam Part 2 of 4 with Complete Solutions

Application of fluorescein should be used in which of the following situations? A. Evaluation of a rigid gas permeable (RGP) lens fit B. Evaluation of soft contact lens parameters C. Evaluation of vascularization of the cornea D. Evaluation of rigid gas permeable lens over-refraction - ANSWER-A. Fluorescein is a valuable tool in evaluating the lens to cornea relationship of a rigid gas permeable lens. A special type of fluorescein (fluorosoft) should be used to evaluate the fitting relationship of a soft contact lens. If the diagnostic rigid gas permeable lens placed on the eye results in minimal movement, which of the following will increase the movement on the lens ordered for the patient? A. Decreasing overall lens diameter B. Increasing overall diameter C. Increasing optic zone diameter D. Increasing sagittal depth - ANSWER-A. Decreasing the overall lens diameter will loosen the fit and increase the movement of a lens. Increasing the overall diameter, increasing the optic zone diameter as well increasing the sagittal depth will all decrease the movement of rigid gas permeable lens. If a contact lens decenter laterally, exposing a portion of the patient's limbus, what change in parameter would improve this situation? A. Decreasing lens diameter B. Increasing lens diameter C. Flattening the base curve D. Increasing the center thickness - ANSWER-B. Decreasing the lens diameter or flattening the base curve will only serve to loosen the lens to cornea relationship and increase the possibility of the lens decentering. Increasing the center thickness will have no bearing on lens centration. Increasing the overall diameter of the lens, however, is one way to improve lens centration When evaluating a diagnostic soft lens on a patient, you notice that movement is sluggish after only a few minutes. Which of the following changes would you make to the lenses that are ordered for the patient?