Test Central Visual Acuity
Snellen eye chart
Snellen Eye Chart procedure
- -Person stands 20 ft away and places something over one eye at a time
- -Person can leave contacts or glasses on
- -Person reads through the chart to the smallest line possible
- -Then record fraction
Snellen eye chart Numerator
Numerator indicates distance person is standing from chart;
Snellen eye chart Denominator
denominator is the distance at which a normal eye could have read that particular line
tested in all individuals over age 40 and those reporting increasing difficulty reading
To test Near vission
- –Use a Jaeger card (handheld vision screener) with various sizes of print. Hold card 14 inches from the eye.
- –Test each eye separately with corrective lenses on.
–Normal result is 14/14 in each eye without hesitancy in reading and without moving card closer or farther away.
decrease in accommodation with aging
To test Color vision Use
Ishihara plates to test for normal color vision
Defects in color vision can result from
disease of the optic nerve, macular degeneration, pathology of fovea centralis, nutritional deficiency, or heredity
Testing for Visual Fields
Peripheral vision of patient is compared to peripheral vision of examiner
–Examiner is positioned at eye level with person, about 2 feet away. Person covers one eye with an opaque card, and the other eye looks straight at examiner. Examiner covers own eye, opposite to person.
–Hold pencil or flicking fingers as a target midline between examiner and person, slowly advance it in from periphery.
Inspection of Cornea and lens
shine a light from side across cornea, check for smoothness and clarity. Should be no opacities in the cornea, the anterior chamber, or the lens behind the pupil.
Inspection of Iris and Pupil
iris should appear flat, with a round regular shape and even coloration. Note size, shape, and equality of pupils. Pupils normally round, regular, and of equal size. Normal adult size: 3 to 5 mm.
•pupils of two different sizes
Inspection of Pupillary Light Reflex
darken the room and person gazes into distance. Advance a light in from the side and note response.
Normal response to Pupillary Light reflex
is constriction of same-sided pupils (direct-light reflex) and simultaneous constriction of the other pupil (consensual light reflex).
R 3 = 3 L
This indicates both pupils 3 mm in resting state and both constrict to 1 mm in response to light.
- test for ability of pupils to adjust to various distances. Ask person to focus on a distant object. Then have person shift gaze to a near object, such as
- examiner’s finger held about 3 inches from the nose.
Normal Accommodation reactions
- •includes dilation of pupils for distance vision and pupil constriction with convergence (axes of
- the eyes inward) for near vision.
•Documentation for all maneuvers is PERRLA (Pupils Equal, Round, React to Light and Accommodation).
Corneal Light Reflex (Hirschberg)
•Assesses parallel alignment of the eye axes.
- •Shine light toward the person’s eyes. Person to stare straight ahead as light is held about 12 inches
•Note the reflection of the light on corneas should be in exactly the same spot on each eye.
(use clock as reference)
•Detects small degrees of deviated alignment by interrupting fusion reflex that normally keeps the two eyes parallel.
•Person stares straight ahead at examiners nose while covering one eye with an opaque card. As eye is covered, note the uncovered eye.
•Normal response is a steady fixed gaze.
- •Uncover the other eye and observe for movement. It should stare straight ahead. If it jumps to
- reestablish fixation, eye muscle weakness exists.
•Repeat with opposite eye.
Six Cardinal Positions of Gaze - EOM
- Normal response is parallel tracking of object with
- both eyes. Mild nystagmus at extreme lateral gaze is normal
Six Cardinal Fields of Gaze uses what CN???
CN 3, 4, 6
•enlarges view of the eye so the media (anterior chamber, lens, vitreous) and ocular fundus (internal surface of retinal) can be inspected.
•It directs a beam of light through pupil to illuminate inner structures.
red glow filing the person’s pupil caused by reflection of ophthalmoscope light off inner retina. Follow red reflex as you move steadily closer to eye.
gray-white arc or circle around limbus due to deposition of lipids
Macular degeneration is the
most common cause of blindness
How to assess the Lacrimal duct
•Inspect for any redness or swelling.
Normally the puncta drain tears into lacrimal sac. Presence of excessive tearing may indicate blockage of nasolacrimal duct. Check this by pressing index finger against sac, just inside lower orbital rim
A symbol eye chart is called ??
•to test for normal color vision.
•If person able to identify all six screening Ishihara plates correctly, then normal color vision.
•Color vision is designated as red/green; blue/yellow; or complete when the person sees only shades of gray.
- •Defects in color vision can result from disease of the optic nerve, macular degeneration, pathology of
- fovea centralis, nutritional deficiency, or heredity.
CN 3 uses what eye muscles
- superior rectus
- Inferior Oblique
- Medial rectus
- Inferior rectus
Lateral rectus used what CN?
Superior oblique eye muscle uses what CN
Color of Fundus
light red to dark brown-red
•prominent landmark, located on nasal side of retina.
–Color: creamy yellow-orange to pink
–Shape: round or oval
Margins: distinct and sharply demarcated, although nasal edge may be slightly fuzzy