individually,  then  both  eyes  together.    Do  not allow the examinee to squint or tilt his head. ·   With  the  graduation  of  the  size  of  the  letters advocated   by   Snellen,   the   visual   acuity   is expressed according to his classical formula V = d/D, where “d” is the distance at which the letters are read, is divided by “D” the distance at which the   letters   should   be   read. Then   record   the smallest line read on the chart from the 20-foot distance as the vision; e.g., 20/20, 20/200. Jaeger Cards When   the   Armed   Forces   Vision   Tester   is   not available,  Jaeger  cards  are  used  to  test  near  vision. There are six paragraphs on each card. Each paragraph is printed in a different size type and labeled as J-1 (the smallest print size), J-2,..., up to J-6. When testing with these cards, you should hold the card at a distance of 14 to 16 inches from the examinee and tell the examinee to read the paragraphs.   Record the   visual   acuity   as   the   smallest   type   he   can comfortably read and record the distance (e.g., J-2 at 14 inches). NOTE: The   distance   of  the  card  from  the examinee  may  be  converted  to  centimeters, but   ensure   the   results   of   the   test   are   also recorded  in  centimeters.    Consistency  is  the key. Armed Forces Vision Tester The   Armed   Forces   Vision   Tester   (AFVT)   is   a semiportable  machine  that  has  the  capability  to  test near and distant visual acuity, horizontal and vertical phorias, and stereopsis (depth perception).  It consists of two rotating drums that hold illuminated slides. The handles on the side of the machine rotate the drums to change   the   slides. A  scoring   key   and   instruction manual are provided with the machine. COLOR VISION TESTING The  Manual of the Medical Department  requires that all applicants for the naval service receive a color vision test.  The Navy has two methods of testing color discrimination: the   Farnsworth   Lantern   Test (FALANT) and the pseudoisochromatic plates (PIP). The FALANT is the preferred test, and in many cases it is  the  test  prescribed  by  the  MANMED  as  the  only acceptable method for testing color vision. Farnsworth Lantern Test The purpose of the Farnsworth Lantern Test is to evaluate color perception. The Farnsworth Lantern is a machine with a light source directed at the examinee. What  the  examinee  sees  is  two  lights  in  a  vertical plane.    These  lights  appear  in  two  of  three  possible colors, either red, green, or white, shown in varying combinations.   The examinee is asked to identify the color combinations from top to bottom at a distance of 8  feet;  the  examiner  rotates  the  drum  to  provide  the different combinations. The examinee must identify a total of nine different combinations. On  the  first  run  of  nine  lights,  if  the  examinee correctly identifies all nine, the FALANT is passed.  If the examinee incorrectly identifies any of the lights, two   additional   runs   of   nine   lights   are   performed without interruption.  The score is the average number of incorrectly identified lights of the second two runs. If the average score is 1 or less, the FALANT is passed. If the score is 2 or more, the FALANT is failed.  If the score is 1.5, the test should be repeated after a 5-minute break.  Do not retest scores of 2 or more since this will invalidate the test procedure. NOTE:  If  examinees  wear  corrective  lenses for   distant   vision,   they   should   wear   them during this test. Pseudoisochromatic Plates If   the   FALANT   is   not   available,   pseudoiso- chromatic  plates  (PIP)  are  used  to  determine  color vision.   Personnel so tested must be retested with the FALANT at the first activity they report to that has a Farnsworth   Lantern. Two   tests   are   available,   the 18-plate   test   and   the   15-plate   test,   each   of   which includes one demonstration plate not used for scoring. When   administering   the   PIP  examination,   you should hold the plates 30 inches from the examinee. Allow 2 seconds for each plate identification, and do not allow the examinee to touch the plates.  To pass the 18-plate test, the examinee must identify a minimum of 14 of the 17 test plates; for the 15-plate test, a minimum of 10 of the 14 test plates.  Record the score in block 64 of the SF 88 as PASSED PIP or FAILED PIP.  Include the number of correct responses (e.g., PASSED PIP 17 of 17 or FAILED PIP 10 of 17). AUDIOGRAM An audiogram is a record of hearing thresholds an individual   has   for   various   sound   frequencies. By 11-11