Optometry & Visual Performance 190 Volume 14 | Issue 2 | June 2026 Visual Acuity Testing (with Crowding) and Contrast Sensitivity Quantify deficit and assess contour interaction/ crowding effect LEA Symbols, HOTV, Snellen/ ETDRS charts, crowding bars, translucent occluder/patch -Explain as a game -Test binocularly first -Monocular at distance and near (use translucent occluder or fog with + if have eccentric fixation). -Full chart --> single line --> single letters with crowding bars -Record exactly: e.g., “20/40 WL with bars OD” -Compare monocular vs binocular -Monocular contrast sensitivity -Neutral density filter eval Matching cards/ gestures for LEA/ HOTV; short segments with praise; use preferential looking if needed Always test with crowding bars; never rely on single uncrowded letters; fatigue can falsely lower scores ≥2-line difference or marked crowding = amblyopia; worse crowded acuity = poorer prognosis; binocular summation = positive sign Fixation Assessment: Visuoscopy Detect & characterize eccentric fixation (present in ~80% strabismic cases) Direct o-scope or visuoscope with bull’s-eye target -Dim lights; occlude non-tested eye; test better eye first -Show bull’s-eye on your hand -Project bull’s-eye onto fundus; ask patient to look at center dot -Observe 30 full seconds -Record: type (central/eccentric), direction, magnitude (degrees), stability, % foveation Test very quickly; parental holding for stability Test better eye first for comparison; poor cooperation can mimic unsteadiness Central + high % foveation = good prognosis; unsteady peripheral EF = deep amblyopia; Expected VA ≈ 20/20 × (EF° + 1) Refractive Assessment Identify amblyogenic refractive error and establish baseline Retinoscope, cycloplegic agents (1% cyclopentolate and/or tropicamide) -Dry retinoscopy & subjective (if possible) -Instill cycloplegic (cyclo or tropicamide 2 drops, 5 min apart); Wait 30–40 min -Cycloplegic retinoscopy and refraction -Keratometry/topography for astigmatism/scissoring reflex -Consider aniseikonia testing Get parental help with drops Cycloplegia / Damp assessment is mandatory in amblyopia workup ; under-cycloplegia misses latent hyperopia High anisometropia or isoametropia confirms amblyogenic factor; compare with BBP findings Best Binocular Prescription (BBP) Find lens powers that maximize binocular function (Sanet-Vergara) Polarized acuity chart, trial frame, Worth 4-dot, stereopsis tests -Place cycloplegic findings in trial frame -Use polarized chart binocularly -Reduce plus (esp. more hyperopic eye) in 0.25 D steps; stop at best binocular visual acuity + comfort -Confirm improvement with Worth 4-dot & stereopsis Keep sessions short; use engaging targets; praise frequently BBP often uses less plus than monocular maximum; do not over-plus Improvement in binocular metrics even if one eye’s monocular acuity drops slightly = successful BBP Binocular & Sensorimotor Evaluation (**Please see previous student corner publications on strabismus) Assess alignment, suppression, correspondence, stereopsis, motility, accommodation Occluder, Worth 4-dot, red lens, stereopsis book, prism bar, flippers, MEM retinoscope -Alignment: Hirschberg, Bruckner, cover test, 4Δ base-out, modified Thorington -Suppression: Worth 4-dot (dist/near), Bagolini -Correspondence: red lens or Bagolini -Stereopsis/Vergence: NPC, phoria, ranges, facility, RDS, local stereo -Motility: 9 gazes for comitance -Accommodation: amplitude, facility, MEM, NRA/PRA Use toys as fixation targets; short bursts; parent assistance Perform binocular tests BEFORE prolonged occlusion; test both distance & near Strong suppression + no stereopsis = poor binocular potential; no ARC + good stereo = favorable Ocular Health & Ancillary Testing Rule out masqueraders and organic causes Slit lamp, dilated fundus, OCT, ERG/VEP, MRI -Anterior segment; dilated fundus exam (mandatory) -Keratometry, OCT, OCT-A, fundus photos, FAF -Color vision and visual field -Electrophysiology (VEP/ERG) if atypical -MRI if optic nerve or intracranial signs Use hand-held slit lamp, 20 D + indirect ophthalmoscope as needed; sedation if necessary for young children Never skip ocular health with dilation in new/ unresponsive cases Normal fundus does NOT rule out early dystrophy; bilateral/nystagmus/progressive = high masquerader risk
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