Accommodation & presbyopia expected amplitude of accommodation

Lecture Topics ...
ACCOMMODATION
&
PRESBYOPIA .

Amplitude of
accommodation.
 The Minimum potential of an eye to
increase optical power while seeing the
near object . Clearly is know as
amplitude of accommodation .
 Note to be important .
If a person need 4 D power to
accommodate . He fulfill it except it he
have 3 D power in reserve.
 Total amplitude of accommodation will
be (3+4= 7)

Procedure for measurement
amplitude of accommodation.
 There are many methods but the most
common is pen – push up method .
 It is used for convergence insufficiency .

 This procedure measures in diopters .
 The ability of a person to change the
focus of crystalline lens in response to
near stimulus .
EQUIPMENTS.
 Near V.A card.
 Tape measure in cm .
 Occlude which is necessary or not.
PIN-PUSH UP METHOD.

Set up .
 The patient is tested while he/she is
wearing habitual distance correction .
 This test may also be performed behind
the chiropter.
 Either the patient or examiner may hold
the near point card or chart .
 The near point card should be well
illuminated .

Step by step procedure .
 Instruct the patient to occlude the left
eye to test the right eye .
 Direct the patient attention to the row of
letters on or two lines better than the
best near V.A line .
 Instruct the patient to keep the letters
clear .
 Slowly move the chart closer to the
patient and ask him to report when the
letters become and remain blurry .

 Measure the distance from the chart to the
patient spectacles . Plane in cm . The linear
measurement is referred to as near point of
accommodation .
 Convert the linear distance into diopters by
dividing the near point of accommodation of
taking reciprocal of it .
 The resultant dioptric represent the patient
amplitude of accommodation .
1/10 = 10 D ( 1 = 100cm )
 Occlude the right eye and test the left and
repeat the same procedure .

Recording .
 Record the testing procedure .
 Record the amplitude of accommodation
in round figure .
 Separately record the result of right and
left eye .
 E.G
AMP OD 7.0 D OS 7.0 /
 OD (right eye ) OS (left eye ) .

Expected Amplitude of
Accommodation.
 The expected amplitude of accommodation decrease with age .
 The two most commonly used system for obtaining the excepted
amplitude of accommodation are .
1) Hofstetters formula .
2) Donders table
 Hofstetters Formula
 Menimum expected amplitude .
15 – 0.25 (age)
Average expected amplitude
18.5 – 0.3 (age )
Maximum expected amplitude
25 – 0.4 (age )

 Minimum excepted amplitude for 1 year age
.
= 15 – 0.25 (age)
15 – 0.25 ( 1 )
15 - 0.25
= ( 14.75 D )
 Minimum excepted amplitude For 10 year
= 15 – 0.25 (age)
15 – 0.25 ( 10 )
15 - 2.5
= ( 12.5 D )

 Minimum excepted amplitude For 30 year .
= 15 – 0.25 (age)
15 – 0.25 ( 30 )
15 - 7.5
= ( 7.5 D ) .
= 15 – 0.25 (age)
15 – 0.25 ( 40 )
15 - 10
= ( 5 D )

 Minimum excepted amplitude For 50 year
= 15 – 0.25 (age)
15 – 0.25 ( 50 )
15 - 12.5
= ( 2.5 D )
= 15 – 0.25 (age)
15 – 0.25 ( 60 )
15 - 15
= ( 0 D )
 Average expected amplitude . For 1 year
= 18.5 - 0.3 (age )
18.5 – 0.3 ( 1 )
18.5 – O.3
= 18.2 D

= 18.5 - 0.3 (age )
18.5 – 0.3 ( 10 )
18.5 – 3
= 15.5 D
= 18.5 - 0.3 (age )
18.5 – 0.3 ( 30 )
18.5 – 9
= 9.5 D

= 18.5 - 0.3 (age )
18.5 – 0.3 ( 40 )
18.5 – 12
= 6.6 D
= 18.5 - 0.3 (age )
18.5 – 0.3 ( 50 )
18.5 – 15
= 3.5 D

= 18.5 - 0.3 (age )
18.5 – 0.3 ( 60 )
18.5 – 18
= .5 D
 Maximum expected amplitude . For 1 year
= 25 – 0.4 (age )
25 – 0.4 (1)
25 – 0.4
= 24.6

= 25 – 0.4 (age )
25 – 0.4 (10)
25 – 4
= 21
= 25 – 0.4 (age )
25 – 0.4 (30)
25 – 12
= 13

= 25 – 0.4 (age )
25 – 0.4 (40)
25 – 16
= 9
= 25 – 0.4 (age )
25 – 0.4 (50)
25 – 20
= 5

= 25 – 0.4 (age )
25 – 0.4 (60)
25 – 24
= 1

 Donders table .
 Donders table for age referenced amplitude of
accommodation .
Age Amplitude of
accommodation
10 y 14 D
15 y 12 D
20 y 10 D
25 y 8.5 D
30 y 7 D
35 y 5.5 D

40 y 4.5 D
45 y 3.5 D
50 y 2.5 D
55 y 1.75 D
60 y 1 D
65 y .5 D
70 y .25 D
75 y 0 D

Accommodation & presbyopia expected amplitude of accommodation

Accommodation & presbyopia expected amplitude of accommodation

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