Comprehensive Guide to Accommodation Testing and Presbyopia Management in Optometry

clincally we measure the ____ to accomodation

stimulus

test objects closer than infinithy

use minus lenses

if "+" power (over distance Rx) is found

less accommodation (lag)

If "0" power is found

response = stimulus (perfect accommodation)

If "-" power is found (px reports vertical at dist Rx)

over-accommodation (lead)

FCC indicates

the accommodation response at near

used to determine the tentative add

NRA/PRA

Negative Relative Accommodation and Positive Relative Accommodation

the change in accommodation relative to a fixed state of convergence

used to balance a tentative addition of a patient

near point of accommodation

the nearest object for which an image point will be formed on the retina

fair point of accomodation

the furthest object point for which an image point wull be formed on the retina

Amplitude of accomodation

near point - far point

Emmetrope

Near point 12.5 cm

Far point (infinity)

8-0 = 8D

Uncorrected Myope

Near point 12.5cm

far point 50 cm

8 - 2D = 6D

Uncorrected Hyperope

near point 12.5cm

dar point 100 cm

8D +1D = 9D

Emetropes with a bifocal

near point a 12.5

far point infinty

Add +1.50

8 - 0 - 1.50D = 6.5D

SEE MATH ON SLIDE

Under accommodation is referred to as

lag

Over accommodation is referred to as

lead

The lag or lead are determined by

the difference between the response and the stimulus given

Mehtods to test accuracy of accomodation

FCC

unfused CC

MEM

Lead and FCC

would have a "minus" add reading FCC

over accomodation at enar

cant relax eyes to meet target

Lag and Fcc

would have high plus on FCC

no accommodating enough at near

cant accomodate to that target distance

Unfused cross cylinder

The procedure is the same as FCC

BUT

- occlude one of the eyes (do test twice)

- dossociationg the eyes with prism 15 BI OD and 6 BU OS

the results of unfused cross cylinder are

higher because vergence accommodation is not involved

unfused cross cylinder If the difference between the 2 eyes is

≥ +0.50 must recheck subjective refraction

Monocular Cross cylinder expected

+0.75 to +1.25

higher because no fusional component

Bonocular Cross cylinder expected

0.50 ± 0.50

plano --> +1.00

Monocular Estimation Method (MEM)

dyamic retinoscopy at px habitual reading distance

measures the lag or lead of accommn. objectively

can be performed outside the phorpter with rx or in the phoropter

pt reads card on retinoscope

observe streak

hold up a hand led lens to neutralize motion seen in quicl streal (2 sec max)

MEM Vertical streak of "with" would show

a lag (add + sph lenses)

Vertical streak of "against" would show

a lead (add - sph lenses)

Vertical streak of "neutral"

no lead or lag

MEM expected

+0.75 ± 0.50

Lead MEM

would have no additional plus power reading on MEM

woudl see against motion (minus)

ocer accomodating at near

Lag MEM

would have a high + reading on MEM

not accmodatin enough at near

with motion

Relative accommodation

change in accommodation relative to a fixed state of convergence. The change is induced by using added plus or minus lenses

SEE SLIDES

BETWEEN TWO ADDS

Go with lower plus

treatment of presbyopia:

Correct the Refractive error for distance first

correction needed for near in each eye should be tested separately - and added to distance correction (ADD)

Near point determined by profession/task of patient

Weakest convex lens with which one can see clearly at near point should be prescribed

range of accommodation

the linear distance between the far point of accommodation and the near point of accommodation in each eye

perform range of accomodation

ONLY after you determine the add for a presbyope

Range of accomodation is performed monoular or boincular

binocular

Range of accommodation procedure

place tentative add on patient over best corrected distance refradction

target is 0.5M letters

move card in to first sustained blur and measure in cm

move card out to first sutstauned blur in cm

record in cm the near and far point

range 15-55cm

the patient should be working at the

midpoint of the range

if the range is too close

decrease add power

if the range is too far away

increase add power

4 ways to determine add

amplitude of accomodation

FCC and PRA/NRA

Tange of accomoadtion (trial framing)

age chart

Binocular Accommodative Facility measures the ability of the eyes to:

stimualte and relax accomodation

converge adn divere the seyes

BAF is influenced by

Accommodative response

Fusional vergence

BAF procedure

test is performed after distance subjective and with beest corrected rx

bright room

0.5M target at 40 cm is held by the patient

+2.00 / -2.00 Flippers and a stop watch/time

start with + lenses

when the patient says clear flip

count seconds to latency if occurs

count the mnuber of cycles (flips/2)

stop at 1 minute

record the number of cycles with latency or unable to clear +/-

BAF normal

8 cpm

if patient passes BAF

no need to MAF

if fails proceed to MAF

Monocular Accommodative Facility

only measures the eyes ability to stimulate and rel

because it is performed monocular! there is no stimulus to converge or diverge

separates accommodative issues from binocular issues

MAF procedure

same as BAF but one eye is patched or occluded

right eye tested first

normal MAF

11 cpm

If the patient fails only one eye during MAF or has a significant difference in the measurement

patient is amblyopic

patient is overminues or overplussed

test was perfrmd incorrectly

Anomalies of Accommodation

Insufficiency of Accommodation

Excessive Accomodation

Insufficiency of Accommodation

fatigue of accommodation (ill sustained)

infacility of accomodation (inertia)

Paralysis of accomodation

Excessive Accommodation

spasm of accommodation

accommodative insufficiency

condition in which accomodative power is constantly less than lower limit of normal range accourdnig to patients age

accommodative insufficiency symptoms

general asthenopia at near, headaches (HA)

accommodative insufficiency treatments

plus lenses /treatment of systemic cause

Sometimes uncorrected myopes report this, but their accommodation usually returns to normal with proper Rx

accommodative insufficiency AA

2.00D or more of a decrease based on formula

accommodative insufficiency BAF

less than 3cpm

difficulty clearing minus

accommodative insufficiency MAF

less than 6 cmp

NRA/PRA

PRA of less than -1.25D

normal NRA

MEM

accommodative insufficiency lag of accommodation >+0.75

Ill sustained/ Fatigue

normal AA, initialy sustained with considerable effort - over time it cannot be maintained

complains of fatigue or eyestrain with prolonged near work (especially at end of day)

reduced AA after repeating test

treat: plus lenses and accomodative facility training

Accommodative in facility (inertia)

Normal amplitude but can not go back and forth

Symptoms - difficulty changing focus from one distance to another, HA, eyestrain, fatigue, blur

reduced NRA and MAF

low NRA and PRA

treatment - correct any refractive error, accommodative rock vision therapy

paralysis of accmodation

accommodative amplitude is either markedly reduced (paresis) or totally absent (paralysis)

blur at near

cause - organic condition or head trauma or accidental instillation of atropine like agent

can be congenital defect or from disease/drugs

treatment: determine underlying cause and correct - plus lenses can help

Excessive accomodation

functional increase in tonus of ciliary muscle, results in a constant accmoodative effect

cause- excessive enar work expeccially in dim or excessive illumination

Accomadative Excess/Spasm

Blurred distance vision after prolonged near work - excessive accommodation

Symptoms - blurred vision at near, blurred vision at distance, HA, eyestrain Creates 'pseudo myopia' in emmetropes

difficulty clearing plus on BAF, possible esophora

low PRA

treatment - correct RE (after cycloplegic exam) low plus lenses for near work and Vision Therapy

Turville Infinity Balance

separate the eyes with physical septum

both eyes see border to keep fusion

deteermine the MPMVA separelry with both eyes open

Humprhiss Immediate contract

fog to 0.75

add 0.25D until best VA

keep a difference of 0.75

check with bichrom test

calculated AC/A ration

15 - amount of more EXO from ditsnce to near / 2.5(stimulus)

15 + amount more ESO from distance to near/ 2.5

normal AC/A

15-0/2.5

6/1