ASSESSMENT OF ACCOMMODATION

 

ACCOMMODATIVE SKILLS

a. amplitude

b. facility

c. accuracy

d. sustainability

e. consistency

f. interactivity

 

AMPLITUDE OF ACCOMMODATION 

1. DONDER'S PUSH UP

a. minimum amplitude = 15 - .25(age in years)

b. monocular vs. binocular

c. overall low sensitivity in non-presbyopes

 

2. MINUS LENS METHOD

a. binocular = PRA


FACILITY OF ACCOMMODATION

 

1. +2.00/-2.00 lens facility

a. 40 cms with 20/30 size target

b. 60 sec duration

c. monocular

d. binocular with suppression checks

e. expected

i. 10-11 cycles / min monocular

ii. <3-4 definitely abnormal 

f. observations

i. OD vs. OS

ii. monocular vs. binocular

iii. decreased rate over time

 

2. near-far fixation facility

a. 20/20 distance letter

b. 40 cms or closer 20/20 letter 

c. expected

i. should be instantaneous

ii. any delay is abnormal


ACCURACY OF ACCOMMODATION

 

(stimulus vs. response function)

can be considered the gain of accommodation

lag of accommodation

 

1. MEM retinoscopy

a. 40 cms or less fixation distance

b. age appropriate reading material

c. OD & OS concurrently

d. loose lenses for neurtralization

e. very brief observations

f. observe both principal meridians 

g. expected

i. between +0.50 and -0.25

 

2. FUSED CROSS CYLINDER

a. an excellent tool for presbyopes
i. predictable and linear responses

ii. accommodation remains stable

b. not a pure lag measurement in non-presbyopes

ii. accommodation responds to the neutralizing lenses

 

3. KINETIC COVER TEST

a. combines cover test and NPC-like target movement

b. constant dissociation leads to more accurate accommodative responses

i. Point A : 40 cm alternate cover test amplitude

ii. Point B : 5 cm alternate cover test

iii. Point C : 40 cm alternate cover test amplitude

c. interpretation

i. positive KCT
Point C cover test amplitude >=5 pd eso relative to Point A

ii. negative KCT