DMV and Vision

Written by Barbara A. Williams.

A senior citizen reported to the Department of Motor Vehicle (DMV) to renew his driver's license. The state of North Carolina refused to issue a renewal driver's license and failed the gentleman because he did not pa ss the eye test. Using the last line projected through the viewing scope that the driver could read successfully, the examiner concluded that the driver could not see clearly objects more than 500 cm away and would be a danger to himself and other drivers if allowed on the road. The examiner explained to the gentleman that if he corrected his distant vision, he would pass and receive a renewal license from the DMV. Before affixing his signature to the form which explained why the state of North Carolina had refused renewal, the elderly man wanted to read the document. This gave the examiner the opportunity to notice that the man read the document at a distance of 75 cm from his eyes.

(Assume a typical value of 2.00 cm for the distance between the retina and the lens system of the eye and a normal reading distance of 25.0 cm.)

  1. What prescription for contacts would you recommend so that the man can pass the vision test at the DMV? Explain using physics principles and show Work.

  2. What is the range of distances over which the man can see with these contacts in place? Show work.

  3. If the man found himself in a situation where he needed to read a map while sitting at the wheel (but of course not reading while driving), what prescription for contacts would you recommend? Show work.

  4. If the man decides to purchase bifocal glasses using your recommended prescriptions in question 1 and 3, what range of distances are objects not clearly seen when he is wearing these glasses? Would this limitation in vision be a safety hazard during m ost driving conditions?

Last updated Nov. 22, 1996.
Copyright Barbara Williams, Univ. of Delaware, 1996.