ACVREP CLVT flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Snellen acuity fraction

The ratio of the test distance to the distance at which a normal eye could read the same line; 20/40 means a normal eye reads that line at 40 feet while the patient needs 20 feet.

logMAR scale

Logarithm of the minimum angle of resolution in arc minutes; each 0.1 logMAR step equals one line on a standard chart; 0.0 logMAR equals 20/20.

M unit notation

Near acuity unit where 1M equals the size of a 20/20 letter at 40 cm (1.45 mm x-height); useful for prescribing magnification and calculating reading add.

Contrast sensitivity function

Measures ability to detect gratings of varying spatial frequencies at low contrast; peak sensitivity around 3–6 cycles per degree; loss may occur with normal acuity.

Pelli-Robson chart

A contrast sensitivity test using large letters of decreasing contrast; scored in log contrast sensitivity units; normal is about 1.8 to 2.0.

Ishihara plates

Pseudoisochromatic plates used to screen for red-green color vision deficiency; not a test of blue-yellow defects; results are qualitative, not a threshold measure.

Farnsworth D-15

A color arrangement test with 15 caps; detects moderate to severe color vision defects and classifies them as protan, deutan, or tritan; pass/fail is dichotomous.

Stereopsis testing

Measures binocular depth perception using random-dot or contour targets (e.g., Titmus, Randot, TNO); thresholds reported in seconds of arc; absence suggests loss of binocularity.

Preferred retinal locus

A retinal area outside the fovea that a person with central vision loss uses for fixation; identified by microperimetry or scanning laser ophthalmoscopy; trained in eccentric viewing.

MNREAD acuity chart

A continuous-text reading chart that measures reading acuity, critical print size, and maximum reading speed; useful for prescribing magnification and predicting functional reading.

Visual perceptual assessment

Tests such as MVPT or TVPS evaluate visual discrimination, memory, spatial relations, figure-ground, and closure; distinguish perceptual deficits from acuity loss.

Visual motor integration

The ability to coordinate visual perception with motor output; assessed by Beery VMI, which requires copying geometric forms; relevant to handwriting and daily tasks.

Confrontation visual field

A quick screening test comparing the patient's field to the examiner's; detects gross defects but not subtle scotomas; normal temporal field is about 90 degrees.

Humphrey visual field

Static automated perimetry that measures threshold sensitivity in decibels at multiple points; produces reliability indices and pattern deviation plots for diagnosing and monitoring field loss.

Essential job functions

Fundamental duties of a job, including visual demands such as acuity, field, color discrimination, and near work; used to determine reasonable accommodations under ADA.

O*NET database

A U.S. Department of Labor database describing occupations, including required visual abilities and work activities; useful for matching low vision clients to suitable jobs.

IEP and 504 plan

Educational documents that specify accommodations and services for students with disabilities; for low vision, may include large print, magnification, lighting, and assistive technology.

Lawton IADL scale

A standardized measure of instrumental activities of daily living such as shopping, cooking, finances, and transportation; scored by independence level; useful for functional assessment.

Barthel Index

A measure of functional independence in basic ADLs (feeding, bathing, grooming, dressing, toileting, mobility, stairs); scores 0–100; higher scores indicate greater independence.

NEI VFQ-25

The National Eye Institute Visual Function Questionnaire, a 25-item measure of vision-related quality of life covering general health, vision, and psychosocial domains; scores 0–100.

PHQ-9 depression screen

A nine-item self-report questionnaire that screens for depression severity; scores 5, 10, 15, and 20 represent mild, moderate, moderately severe, and severe depression.

MoCA cognitive screen

Montreal Cognitive Assessment; a 30-point screening tool for mild cognitive impairment; scores below 26 suggest impairment; adjust for education and sensory loss.

Screen reader software

Assistive technology that converts digital text to speech or braille (e.g., JAWS, NVDA, VoiceOver); essential for computer access when vision is insufficient for screen reading.

Video magnifier (CCTV)

An electronic device that projects an enlarged image onto a screen; offers adjustable magnification, contrast, and color; useful for reading and near tasks.

Handheld magnifier

A convex lens used for spot reading; magnification depends on lens power and eye-to-lens distance; higher power yields smaller field and shorter working distance.

Telescope magnification formula

Magnification equals the focal length of the objective divided by the focal length of the eyepiece; higher magnification reduces field of view and requires steady fixation.

Equivalent power formula

For a near magnifier: equivalent power = F + (D × d), where F is lens power in diopters, D is accommodation or add, and d is lens-to-eye distance in meters.

Eccentric viewing training

Teaching a person with central scotoma to fixate with a preferred retinal locus; uses clock-face or quadrant cues and practice to improve reading and spotting.

Glare control filters

Tinted lenses (yellow, orange, gray, or polarized) that reduce glare and enhance contrast; selection depends on lighting conditions and task; avoid excessive darkness.

Typoscope

A non-optical device with a slot that isolates one line of text and blocks glare from surrounding white paper; improves reading comfort and tracking.

Spotting with telescope

The skill of locating and aligning a handheld telescope on a target; involves anchoring, scanning, and steadying; taught before distance viewing tasks.

Device abandonment

Discontinuation of a prescribed low vision device; causes include poor training, unrealistic expectations, discomfort, or inadequate magnification; address with follow-up and adjustment.