2. Assessment of Accommodation

What three components should be evaluated when assessing a suspected accommodative disorder, and which tests assess each component?

• Amplitude: maximum accommodative ability

  • Push-up test

  • Push-away test

  • Minus-lens test

  • Dynamic retinoscopy

• Facility: ability to rapidly stimulate and relax accommodation

  • Lens-flipper testing

• Response or accuracy: accommodation produced relative to the accommodative demand

  • MEM retinoscopy

  • Nott retinoscopy

  • Autorefraction

Why must accommodative amplitude, facility, and response be tested separately?

The result of one accommodative test cannot reliably predict the result of another because amplitude, facility, and response assess different aspects of accommodation.

Therefore, a patient may have:

• Normal accommodative amplitude but impaired facility

• Normal facility but an abnormal accommodative response

• An abnormality on one test with normal results on the others

How is the push-up test performed to measure accommodative amplitude, and what is the endpoint?

• Test monocularly first, repeating 3 times per eye, then test binocularly.

• Use a 20/30 target mounted on an accommodative rule held against the forehead.

• Move the target toward the patient at 1–2 cm/second.

• The endpoint is the first sustained blur, meaning the target remains blurry rather than briefly clearing.

• Convert the endpoint distance in meters to accommodative amplitude:
  AA (D) = 1 / distance (m)

Why does the push-up test tend to overestimate accommodative amplitude?

As the target approaches, relative-distance magnification makes the target appear larger.

For example, a 20/30 letter at 40 cm subtends approximately the same angle as a 20/120 letter at 10 cm, allowing the patient to recognize the target despite increasing blur.

How does push-away accommodative-amplitude testing differ from push-up testing, and can the same norms be used?

In push-away testing:

• Begin with the target close enough to be blurred.

• Move the target away from the patient.

• Ask the patient to name the letters.

• Record the point at which the letters first become clear.

Evidence comparing push-up and push-away results is mixed:

• Two studies found no meaningful difference.

• One study found a difference of approximately 2–3 D.

Therefore, the methods may produce similar results, but the same normative values should not automatically be assumed to apply across both methods.

How is accommodative amplitude measured with the minus-lens method, and how is the final AA calculated?

• Test monocularly with a near target at a fixed working distance.

• Add minus lenses until the patient reaches the sustained-blur endpoint.

• Add the accommodative demand of the working distance to the minus-lens amount.

Formula:

AA = minus-lens magnitude + working-distance demand

Why does minus-lens testing generally produce a lower accommodative-amplitude measurement than push-up testing?

Minus lenses:

• Stimulate accommodation while the target remains at a fixed distance

• Cause image minification, making blur more noticeable and the endpoint occur sooner

• Do not provide the relative-distance magnification present during push-up testing

How may accommodative-amplitude measurements differ among push-up, minus-lens, and dynamic-retinoscopy methods?

Different methods may produce systematically different results:

• Minus-lens AA: generally less than push-up AA

• Push-up AA: may be elevated by relative-distance magnification

• Dynamic-retinoscopy AA: presented in the slide as greater than push-up AA

How does objectively measured accommodative amplitude change with age.

Objectively measured, minus-lens-stimulated AA decreases with age in a nonlinear, sigmoidal or S-shaped pattern, rather than decreasing at a constant linear rate.

• AA remains relatively stable early in life.

• AA then declines more rapidly with increasing age.

• The rate of decline slows as AA approaches zero.

What are Hofstetter’s formulas for AA?

• Average AA = 18.5 − 0.30(age)

• Minimum AA = 15 − 0.25(age)

Why should Hofstetter’s age-expected accommodative amplitude values be interpreted cautiously in children?

Hofstetter’s equations may overestimate the accommodative amplitude expected in children, so applying the formulas rigidly can produce many apparent cases of accommodative insufficiency.

In children ages 6 to 10 years, the percentage classified as having accommodative insufficiency depended strongly on the cutoff:

• 2.00 D below average: 62.5% monocular, 29.2% binocular

• Below Hofstetter minimum: 51% to 57% monocular, 22.2% binocular

• 2.00 D below minimum: 33% to 35% monocular, 11% binocular

Clinical takeaway: A mildly reduced AA relative to Hofstetter’s formulas does not, by itself, establish accommodative insufficiency. Interpret AA with symptoms, binocular findings, and other accommodative tests.

What accommodative-amplitude finding is considered clearly reduced and more suggestive of accommodative insufficiency?

An accommodative amplitude more than 2.00 D below Hofstetter’s age-predicted minimum is considered reduced.

What does accommodative facility measure, and why can it be abnormal despite normal accommodative amplitude?

Accommodative facility measures the ability to rapidly and repeatedly stimulate and relax accommodation.

• It is associated with accommodative symptoms.

• It indirectly assesses the ability to sustain accommodative performance over time.

• Facility can be reduced even when accommodative amplitude is normal because amplitude measures the maximum available accommodation, not the speed or flexibility of the response.

• Reduced facility may improve with vision therapy.

How do far-near testing and lens-flipper testing differ when assessing accommodative facility?

Far-near testing:

• Patient alternates fixation between distant and near targets.

• Provides a primarily qualitative assessment.

• Relies on the patient’s report and the examiner’s subjective evaluation.

• Often lacks a suppression check.

Lens-flipper testing:

• Patient alternates between plus and minus lenses while viewing a stationary target.

• Provides a quantitative result in cycles per minute.

• Can incorporate a suppression-control target, especially during binocular testing.

What type of target should be used for accommodative-facility testing, and why may a suppression control be needed?

Use a detailed near target with small, approximately 20/30 letters, such as an accommodative rock card.

• The small letters provide a sensitive endpoint for detecting blur and determining when the target becomes clear.

• During binocular facility testing, use an acuity-suppression target or comparable suppression check.

• Without suppression control, the patient may suppress one eye and appear to clear the lenses binocularly, producing an artificially normal result.

How should accommodative facility be measured with lens flippers?

• The examiner times the test for 1 minute, counting complete cycles.

• Keep the timer face down so the patient cannot pace the response based on the remaining time.

• The examiner controls the flipper.

• Rotate or flip the lenses rather than moving the entire flipper up and down.

• Hold the lenses level and directly in front of the eyes.

• Flip only after the patient reports that the target is clear.

How can the examiner maintain a constant target distance during accommodative-facility testing?

Use either:

• A target mounted on a near-point rod, or

• A nonstretch string attached to the target

How should binocular accommodative-facility testing be selected based on the patient’s age and accommodative amplitude?

• Children ages 8 to 12: Test with ±2.00 D flippers at 40 cm.

• Patients ages 13 to 30: Consider binocular amplitude-scaled facility testing, adjusting both the test distance and lens power to binocular AA.

Amplitude-scaled formulas from the slide:

• Test distance in cm = 45% of binocular AA

• Flipper lens power = 30% of binocular AA ÷ 2

Use a single flipper of the calculated power and do not stack flippers.

How should suppression be monitored during binocular accommodative-facility testing?

Use a suppression-control target, such as:

• A bar-reader target with Polaroid glasses

• An acuity-suppression chart, using the specified 2D/3D lines or lines 4-6

Before testing:

1. Confirm the Polaroid orientation, with the smooth side down.

2. Demonstrate the suppression check.

3. Ask whether either bar or target component becomes dark or disappears.

4. Explain that suppression can occur despite both eyes remaining open.

During and after testing:

• Require the letters to remain clear and single.

• Ask about suppression again after the test.

What instructions should be given during accommodative-facility testing to obtain an accurate endpoint?

• The endpoint is when the target becomes clear and single.

• Children: Have the patient read or name letters, allowing the examiner to observe performance during and between flips.

• Adults: Have the patient say “now” or read a letter once the target becomes clear and single.

• Avoid asking, “Is it clear?”, because that question may cue the patient to respond before a true clear endpoint is reached.

• Flip the lenses only after the patient demonstrates or reports the correct endpoint.

How is accommodative facility demonstrated, performed, and scored?

• Demonstrate one complete cycle before testing.

• Begin with the plus lenses.

• The patient must clear both the plus and minus lenses.

• One cycle = plus cleared + minus cleared.

• Record the number of cycles per minute (cpm).

• Monitor whether performance slows during testing and whether one lens is harder to clear.

• If the patient cannot clear a lens, compare performance with the age-expected value.

What are the expected accommodative-facility values?

Binocular facility

• Ages 8–12 with ±2.00 D: 5 cpm ± 2.5

• Ages 13–30 with amplitude-scaled testing: 10 cpm

Monocular facility

• Ages 8–12 with ±2.00 D: 7 cpm ± 2.5

• Ages 13–30 with ±2.00 D: 11 cpm ± 5

What is the expected binocular accommodative facility for teenagers and pre-presbyopic adults using ±2.00 D flippers with suppression control?

The Zellers binocular norm is:

• 8 cpm

• Approximately ±3 to 5 cpm

This norm applies to binocular testing with:

• ±2.00 D flippers

• A suppression check

What does a substantial difference between right-eye and left-eye monocular accommodative facility suggest?

A substantial interocular difference, such as 4 cpm, may:

• Identify a unilateral accommodative limitation

• Restrict the patient’s binocular facility performance

Using Zellers norms, how should accommodative-facility results be classified?

High fail or borderline reduction

• Binocular: greater than 3 but less than 8 cpm

• Monocular: greater than 6 but less than 11 cpm

• Retest for an additional minute and interpret with symptoms and other findings.

Low fail or clearly reduced

• Binocular: less than 3 cpm

• Monocular: less than 6 cpm

Clinical takeaway: A borderline score should be repeated and interpreted in context, while a score below the low-fail threshold provides stronger evidence of deficient accommodative facility.

During binocular accommodative facility testing, what do plus and minus lenses assess?

• Plus lenses: require relaxation of accommodation. The resulting tendency toward divergence must be compensated by positive fusional vergence (PFV) to keep the target single.

• Minus lenses: require increased accommodative effort. The resulting tendency toward convergence must be compensated by negative fusional vergence (NFV) to keep the target single.

A patient has difficulty clearing one side of the flippers during binocular accommodative facility testing. What mechanisms may be responsible?

Difficulty clearing plus lenses:

• Poor relaxation of accommodation and/or

• Poor positive fusional vergence

Difficulty clearing minus lenses:

• Reduced ability to stimulate accommodation and/or

• Poor negative fusional vergence

Clinical takeaway: Binocular facility cannot isolate accommodation from vergence. Compare the result with monocular facility and relevant fusional vergence findings to determine which system is limiting performance.

If binocular accommodative facility is reduced, how can monocular facility distinguish accommodative from vergence dysfunction?

• Binocular reduced + monocular reduced: suggests accommodative dysfunction, specifically reduced accommodative facility.

• Binocular reduced + monocular normal: suggests vergence dysfunction, because accommodation works normally when fusion is removed.

What tests objectively assess accommodative accuracy or response, and what should be examined?

Accommodative accuracy is the accommodative response produced relative to the accommodative demand.

It may be assessed using:

• MEM dynamic retinoscopy

• Nott dynamic retinoscopy

• Autorefraction

• Modified Bell retinoscopy

Assess:

• OD and OS separately

• Both principal meridians in each eye

These tests determine whether the patient shows an appropriate response, an accommodative lag, or an accommodative lead.

How is MEM dynamic retinoscopy performed, and why is no working-distance correction needed?

• Perform MEM with the patient wearing the full distance correction and normal room illumination

• Place the near target in the same plane as the retinoscope aperture, so the target and retinoscope are equally distant from the patient.

• Use the patient’s typical near working distance:

  • Approximately 40 cm for adults

  • Approximately 33 cm or Harmon distance for children

• Observe the reflex while the patient reads the near target.

• Insert trial lenses briefly at the spectacle plane to find neutrality.

How are with motion and against motion interpreted during MEM dynamic retinoscopy?

• With motion: add plus

  • The patient is focused behind the near target.

  • Indicates underaccommodation, or a lag of accommodation.

• Against motion: add minus

  • The patient is focused in front of the near target.

  • Indicates overaccommodation, or a lead of accommodation.

• Neutral reflex: the patient is focused at the plane of the near target.

What should be recorded during MEM if neutrality falls between two trial-lens powers, and how quickly should lenses be introduced?

• Record the first lens power that produces neutrality.

• If neither lens produces neutrality, select the power that is closest to neutrality.

• If two lens powers are equally close, record their mean.

• Hold the lens in front of the eye for only half a second.

How is Nott dynamic retinoscopy performed, and how does the neutralization distance indicate accommodative lag versus lead?

• Keep the near target fixed at the patient’s reading distance.

• The examiner moves the retinoscope forward or backward until the reflex becomes neutral.

• Use normal or slightly dim room illumination.

• Measure the distance from the patient to the retinoscope at neutrality, commonly using a string attached to the retinoscope.

How is Nott dynamic retinoscopy interpreted?

Interpretation:

• Neutrality farther from the patient than the target indicates an accommodative lag.

• Neutrality closer to the patient than the target indicates an accommodative lead.

• Neutrality at the same distance as the target indicates an accurate accommodative response.

The amount of lag or lead is calculated from the difference in dioptric demand

How can autorefraction objectively assess accommodative accuracy or response?

Using the WAM-5500 autorefractor, refractive response can be recorded continuously for 2 minutes while the patient views accommodative demands ranging from 0 to 5.00 D.

The measured accommodative response is compared with the target demand to identify:

• Lag: response is less than the accommodative demand

• Lead: response exceeds the accommodative demand

• Accurate response: response approximately matches the demand

This provides an objective measure of static accommodation that can be compared with the patient’s visual discomfort.

How does Modified Bell retinoscopy assess accommodative response in young children?

• Keep the distance between the examiner and child fixed.

• Move the near target toward the child until the retinoscopic reflex reaches neutrality.

• The fixed examiner distance represents the child’s accommodative response.

• The target distance at neutrality represents the accommodative demand.

• Compare response with demand to determine accommodative accuracy.

Interpretation:

• Demand greater than response: accommodative lag

• Response greater than demand: accommodative lead

• Demand approximately equals response: accurate accommodative response

What moves to reach neutrality in MEM, Nott, and Modified Bell dynamic retinoscopy?

• MEM: The examiner briefly introduces lenses while the target and retinoscope remain in the same plane.

• Nott: The examiner and retinoscope move while the target remains fixed.

• Modified Bell: The target moves while the examiner-retinoscope distance remains fixed.

What is the average/expected accommodative accuracy/response?

+0.25 D to +0.75 D

How should an abnormally low or high plus finding on accommodative-response testing be interpreted?

Less plus than expected, plano, or a negative finding:

• Indicates overaccommodation or a lead

• May suggest accommodative excess

• May also occur with high exophoria and poor positive fusional vergence, or poor base-out fusion

More plus than expected, especially +1.00 D or greater:

• Indicates underaccommodation or an excessive lag

• May suggest accommodative insufficiency

• May also occur with high esophoria and poor negative fusional vergence, or poor base-in fusion

How can the ability to sustain accommodation and detect accommodative fatigue be assessed?

Assess whether accommodative performance deteriorates with repeated or prolonged testing using:

• Repeated push-up testing: looks for declining accommodative amplitude

• Accommodative-facility testing: looks for slowing or increasing difficulty clearing lenses

• Accommodative-response testing: looks for a changing or increasing lag during sustained near fixation

A worsening result over time suggests reduced sustaining ability or accommodative fatigue rather than merely a low single measurement.