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Glossary »
L

  • lag of accommodation

    The dioptric difference between the accommodative stimulus and the accommodative response, where the eye under-accommodates for a near target. A normal lag is between 0.50 to 0.75 D, while a lag >1.00 D is considered abnormal and may cause symptoms like eyestrain, headaches, and blurred vision at near.

    Lag of accommodation can be measured objectively using dynamic retinoscopy techniques such as MEM or Nott retinoscopy. It may occur due to reduced accommodative ability or uncorrected hyperopia. Treatment options include prescribing plus lenses at near or vision therapy to improve accommodative function.

  • latent nystagmus

    A conjugate, horizontal jerk nystagmus that manifests only under monocular viewing conditions. The fast phase always beats toward the fixating eye, while the slow phase drifts nasally.

    Latent nystagmus is associated with infantile strabismus, amblyopia, and dissociated vertical deviation, and is thought to arise from maldevelopment of cortical binocular connections. It may convert to manifest latent nystagmus if binocularity is disrupted.

  • lead of accommodation

    The dioptric difference between the accommodative stimulus and the accommodative response, where the eye over-accommodates for a near target. It may cause blurred vision at near due to excessive accommodation.

    Potential causes include accommodative spasm and uncorrected myopia. Treatment options involve reducing accommodative demand through minus lenses at near or vision therapy to improve accommodative control.

     

  • levoversion

    The conjugate movement of both eyes to the left, a type of version. It occurs due to simultaneous contraction of the left lateral rectus and right medial rectus muscles.

  • low vision

    Significant, permanent vision impairment that cannot be fully corrected with glasses, contact lenses, medications, or surgery. It results from eye diseases, congenital abnormalities, or injuries that damage the visual system, preventing satisfactory vision even when refractive errors are corrected. Low vision patients experience reduced visual acuity, contrast sensitivity, or visual fields that impair daily functioning like reading, mobility, and face recognition, yet some usable vision remains.