lead of accommodation

Lead of accommodation is an accommodative response greater than the accommodative stimulus, which leaves the eye relatively myopic for the target. On monocular estimate method (MEM) retinoscopy a lead shows as against motion, while neutrality means the response equals the stimulus.^1,2

For distance targets a lead of about 0.5 D is normal, and near targets normally draw a lag instead.² The average lag at near is 0.25 to 0.50 D in children and young adults, and clinicians measure it routinely with MEM retinoscopy.³

A lead at near points to overaccommodation. Accommodative excess can produce it, and so can high exophoria with reduced positive fusional vergence, where accommodative convergence props up fusion at the cost of blurred vision.⁴ An uncorrected myope may also show less plus than expected, so the MEM result is read only with the distance refractive error fully corrected.⁴ A lead directs treatment toward relaxing accommodation, with vision therapy that emphasizes plus acceptance.³