cover test

Question 1

what is cover/uncover test?

Answer 1

• to detect any manifest deviations

i. e. a tropia

Question 2

what is alternating cover test?

Answer 2

• to detect any latent deviations

i. e. a phoria

Question 3

how to carry a cover test?

Answer 3

• check vision/visual acuities monocularly
• target should be one line better than worst acuity
  i. e. if RE sees 6/6 and LE sees 6/9 target should be 6/12
• if VA<6/60 , use a pen torch

Question 4

where should the target for cover test be?

Answer 4

• target should be one line better than worst acuity

Question 5

what is the cover/uncover test procedure ?

Answer 5

• check for manifest deviations i.e. tropias
• cover RE and watch LE for any movement
• if no movement, cover LE and watch RE
• repeat at 33cm with a budgie stick ( with and without glasses)

Question 6

how to record movement ?

Answer 6

. if there is any movement, record

• direction: i.e. esoT, exoT, hyperT, hypoT ( vertical deviations are recorded as the higher eye)
• magnitude: i.e. the size of the deviation

Question 7

how is right esotropia seen in cover/uncover test?

Answer 7

. the RE moved OUT when the LE was covered
. therefore, the eye was naturally IN
. this is a right esotropia

Question 8

how can the magnitude of a tropia be measured in cover/uncover test ?

Answer 8

. this can be measured using a prism bar

Question 9

what is the alternating cover test procedure?

Answer 9

• checks for latent deviations i.e. phorias
• during the alternating cover test, the occluder is moved constantly from one eye to the other thus ensuring that one eye is always covered and therefore, achieving maximum dissociation
• repeat at 33 cm with a budgie stick ( with and without glasses)

Question 10

how to record movement in alternating cover test procedure ?

Answer 10

• direction i.e. esoP, exoP, hyperP, hypoP
• magnitude: i.e. the size of the phoria
• recovery: i.e. how quickly does the eye go back to its normal position once the cover is removed for the last time. is it rapid, moderate or slow?

Question 11

what are common alternating cover test errors?

Answer 11

. common errors include moving the cover too quickly. leave the cover over the eye for 3 seconds
. not checking recovery

Question 12

how is an exophoria displayed in alternating cover test?

Answer 12

• the RE moved IN when the cover was removed from that eye
• therefore, the eye was OUT behind the cover
• the LE moved IN when the cover was removed from that eye
• therefore, the eye was OUT behind the cover
• this is an exophoria
• phorias are always in both eyes

Question 13

how is alternating cover test magnitude measured ?

Answer 13

• measured using a prism bar

Question 14

how is alternating cover test recovery recorded ?

Answer 14

• this is how quickly the eye goes back to its normal position once the cover is removed for the last time
• was it rapid, moderate or slow

Question 15

what is the cover test routine ?

Answer 15

• the routine should include
  . cover/uncover test
  . alternating cover test

. check vision/VAs
. target is one line better than worst acuity
. perform cover/uncover test
. perform alternating cover test
- check for:
. direction
. magnitude
. recovery