ACVREP CLVT cheat sheet

Distance acuity: Snellen notation (20/20) or logMAR; logMAR = log10(minimum angle of resolution in arcmin); 20/20 = 1.0 logMAR equivalent; each 0.1 logMAR step ≈ one line.

Near acuity: M units (1M = 1.45 mm x-height at 40 cm); Jaeger notation is not standardized; convert M to logMAR via logMAR = log10(M) + 0.3 (at 40 cm).

Visual field: confrontation ~30° temporally; kinetic perimetry (Goldmann) defines isopters; static threshold perimetry (Humphrey) yields dB sensitivity; normal field extends ~60° nasal, 90° temporal, 50° superior, 70° inferior.

Contrast sensitivity: Pelli-Robson scores in log CS (normal ~1.8–2.0); CSV-1000 reports log CS at 3, 6, 12, 18 cycles/degree; loss can occur with normal acuity.

Color vision: Ishihara (red-green screening), Hardy-Rand-Rittler (red-green and blue-yellow), Farnsworth-Munsell 100-hue (error score) and D-15 (dichotomous pass/fail).

Stereopsis: Titmus fly (gross), Randot circles (40–400 sec arc), TNO (random dot, 15–480 sec arc); absence indicates binocularity loss; monocular cues may allow gross depth.

Visual perceptual/motor: Motor-Free Visual Perception Test (MVPT), Beery VMI (visual-motor integration), TVPS (visual perception); screen for visual agnosia, neglect, and ocular motor dysfunction.

Literacy: assess reading acuity (MNREAD), critical print size, reading speed (words/min), and writing legibility; consider magnification needs and preferred retinal locus (PRL).

Work history: document job title, essential functions, visual demands (acuity, field, color), accommodations used, and barriers; use task analysis and O*NET/functional capacity profiles.

Educational performance: review IEP/504, reading level, note-taking, assistive technology (screen readers, magnification), and classroom lighting; assess print size and contrast needs.

ADL/IADL: use standardized tools (e.g., Lawton IADL, Barthel Index, FIM) and observation; assess grooming, cooking, shopping, medication management, financial management, transportation.

Technology use: inventory devices (smartphone, computer, tablet), screen reader (JAWS, NVDA, VoiceOver), magnification software (ZoomText, MAGic), OCR apps, and training needs.

Quality of life: use validated instruments (NEI VFQ-25, Impact of Vision Impairment [IVI], Low Vision Quality of Life [LVQOL]) covering emotional, social, and functional domains.

Psychosocial: screen for depression (PHQ-9), anxiety, social isolation, adjustment to vision loss; consider referral to counseling and support groups.

Cognitive function: screen with MMSE or MoCA; distinguish visual impairment from cognitive deficits (e.g., visual agnosia vs. memory loss); consider dementia's impact on rehabilitation.

Environmental and safety: home hazard assessment (lighting, contrast, clutter), fall risk, driving cessation, and community access; coordinate with OT and social services.

Device categories: optical (magnifiers, telescopes, prisms), non-optical (lighting, filters, large print, typoscopes), electronic (CCTV, portable video magnifiers, smartphone apps), and assistive technology (screen readers).

Magnification calculation: required magnification = (desired acuity / present acuity) × (reference distance / working distance); e.g., 20/200 to 20/40 needs 5× at same distance.

Equivalent power: for near magnifiers, equivalent power = F + (D × d) where F is lens power (D), D is add or accommodation, d is lens-to-eye distance in meters; or use M = D/4 (D in diopters) at 25 cm.

Telescope magnification: M = F_objective / F_eyepiece; field of view decreases as magnification increases; exit pupil and eye relief affect usability.

Training sequence: demonstrate, explain, practice in controlled setting, then generalize to real tasks (reading mail, labels, TV, street signs); include spotting skills for telescopes.

Eccentric viewing: teach use of preferred retinal locus (PRL); use clock-face or quadrant method; practice steady fixation and scanning.

Lighting and glare: adjust intensity and angle; use full-spectrum or task lighting; filters (yellow, orange, gray) reduce glare and enhance contrast; avoid glare sources.

Follow-up: evaluate comfort, speed, comprehension, and device abandonment; modify magnification, working distance, or device type; document outcomes and training progression.