Measuring near lag of accommodation

Assessing accommodative function – including near lag of accommodation, is a vital component of understanding your patient’s risk profile for myopia. Accommodation and binocular vision status can influence myopia onset and progression in both children and adults. 

Research suggests that esophoria and increased accommodative lag are associated with myopia compared to emmetropia.1,2 Myopic children and young adults show reduced response to lens-induced blur, reduced accommodative facility, greater variability in accommodative behaviour, and greater accommodative convergence (higher AC/A ratios) relative to emmetropes.3-6 Higher accommodative lag may be also seen in individuals who undergo myopic shifts, regardless of whether they were originally myopic or non-myopic.4

The simplest way to measure accommodative lag is with near retinoscopy, using the MEM retinoscopy technique. Watch this technique in action.

1. Position yourself 33–40 cm from the patient, at their near working distance, to create an accommodative demand of 2.5–3 D.
2. Ask the patient to look at your nose or at a near fixation card attached to your retinoscope. Ensure the patient is wearing full distance correction.
3. Without a correcting lens in place, sweep the retinoscope horizontally and vertically in front of the pupil, and note the motion of the light reflex (e.g. with, against, or neutral). 
4. Repeat this step, but introduce lens flippers (±1.00, ±1.50 and ±2.00 flippers are useful) in order to neutralize the reflex. 
5. Try ±1.00 first, and if you still observe ‘with’ movement, move to ±1.50. If the reflex reverses, your answer is halfway between the two lenses such as +1.25.
6. Identify the lens that produces neutralisation or the first reversal of movement – this final lens represents the accommodative response. No additional correction value is required.

Some clinicians prefer to have the patient view a near fixation card as opposed to fixating on their nose, and this typically produces a slightly less plus result. There is no universally recommended method, so it may be practical to choose one approach (with or without a fixation card), and use it consistently to allow easy clinical comparisons. 

Measuring lag with a fixation card can offer a picture that feels closer to real-world visual behaviour because it reflects active accommodation. On the other hand, measuring with a nose fixation target may reduce the influence of the test itself on subconscious accommodative tone.

You can also measure accommodative lag with the fused cross-cylinder (FCC) card in the phoropter. 

In practice, this method can sometimes produce results that are at odds with free-space techniques. Active accommodators may become aware of the phoropter in front of their face, which can influence the response and occasionally result in an accommodative lead on FCC, even when a lag has already been seen with near retinoscopy.

A previous study reported significantly lower accommodative response measurements with FCC compared to MEM or Nott retinoscopy, which aligns with these observations.8 Free-space techniques more closely replicate normal viewing conditions, which might produce more reliable measurements. Not to forget, MEM retinoscopy can also be a lot faster to perform.

If you’re lucky enough to have an open-field autorefractor, you can measure accommodative lag using what is often considered the gold standard approach. 

One study found good agreement between MEM and Nott retinoscopy, although both methods seemed to underestimate accommodative lag compared with open field autorefraction.7 The interaction between examiner and patient during retinoscopy, along with the examiner’s ability to observe and interpret a stable accommodative response, may capture aspects of behaviour that autorefraction cannot. This could mean that retinoscopy techniques and autorefraction may be measuring slightly different components of the accommodative response.

Near retinoscopy remains a quick and practical way to measure accommodative lag. With a retinoscope and a set of flippers, you can typically obtain a reliable result in under 20 seconds, which gives you enough time to observe the stability of the reflex and neutralise it accurately. 

Normal values fall between +0.50 and +1.00, with higher results indicating an increased risk for myopia.9

1. Near retinoscopy, especially with the MEM method, provides a fast and reliable way to assess accommodative lag in routine clinical practice.
2. Accommodative lag, and other binocular vision findings such as reduced facility and increased AC/A ratios can offer useful insight into a patient’s myopia risk profile.
3. Alternative methods including near fixation cards, fused cross-cylinder, and open-field autorefraction can be used, although each technique has its caveats.

Discover our Binocular Vision Fundamentals online course – designed to build your confidence and clinical precision in assessing and managing BV. 

You’ll learn our practical two-system approach to accommodation and vergence, step through key diagnostic tests, and refine your prescribing and management decisions. The course also explores how to communicate BV findings with patients and why BV is essential in myopia management – always with a sharp focus on clinical application.

Enjoy video demonstrations, real-world case examples, and downloadable chairside infographics you can use immediately in practice.