Download Visual fields

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PHYS DX
Conjunctiva—very vascular; bulbar and palpebral
Sclera—white; check foreign bodies, lesions
Cornea—look for arcus, ulcerations, scars
 Look at depth of anterior chamber
 Angle formed between cornea and iris
 Shine light tangentially at eye (from the side)
 If narrow angle, iris bulges forward and you see a crescent-shaped shadow
 Iridectomy—slice iris to let fluid flow
Evaluate iris
 Pattern should be clearly invisible and symmetrical
 Iridectomy for acute narrow-angle glaucoma
 Talked too fast __________________
Table 7-7
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Pupil
Inspect size, shape, equality, response to light
Normal size and shape  round; 2-3 mm Note: 5% of pop. have unequal pupil size
Abnormal  neurologic disease, CNS disease, Horner’s
Mydriasis
 Pupillary enlargement > 6mm
 Coma—diabetic, alcoholic, uremia, epilepsy
 Acute glaucoma
 Sympathomemetic drugs (dilating drops)
 Severe brain damage
Miosis
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Constricted < 2mm
Light accommodation
Morphine
Iritis
Pupils—irregular shaped
 Neurosyphilis
 Head trauma
Assessment—reaction to light
 If shine light in eye, should constrict
 Direct—same eye
 Consensual—opposite eye
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Optic nerve—70% afferent
 80% visual
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PHYS DX
optic nerve  chiasm  tract  __________ visual cortex
20% of fibers enter tract and go into lateral geniculate body (pupillary fibers)
Edinger Westphal nucleus
 Crossover of fibers to superior cuniculus
 Some go back to other eye
 Ciliary ganglion
 Short ciliary nerve
 Constriction of pupillae muscle
 Superior cuniculus of pretectile area of midbrain
Afferent defect—neither eye responds when light is shined in bad eye
Efferent defect—bad eye does not respond regardless of which eye you shine the light in
Near reaction pupillary response
 Ask patient to look at distant object, then put an object ~ 10 cm from bridge of noes, eyes
will accommodate
 Best to follow same object as it is brought nearer
Accommodation response
 Pupils constrict
 Eyes converge
 Lens accommodates (lens thickens)
 Mediated primarily by CN III (associated with crossover)
Absent accommodation or near syphilis
 Lesions of
 All lesions affecting direct/indirect
 Temporal parietal optic radiation
 Visual cortex
 Motor area
 Extraocular muscles (myasthenia gravis)
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Negative response to light but positive response to accommodation maybe seen with neuropathy
associated with diabetes or syphilis
Evaluate 6 cardinal positions of gaze
 Paralysis of extraocular muscles (ophthalmoplegia)
 Instruct patient to follow object making a wide H in the air
 Should see conjoint motion if normal (move together)
 Paralytic strabismus
 Weakness or paralysis of one or more extraocular muscles
 Paralytic = true deviation
Table 7-1 (library)
 Extraocular muscles
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PHYS DX
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Superior rectus
 Adduction
 Intorsion (12:00 position on cornea rotates nasally)
 Elevation—eye moves up
Table 7-5 Abnormal signs (if lesion)
 Superior rectus—eye will not go superior and temporal
Nystagmus—oscillation of eyes
 True nystagmus occurs in field of full binocular vision—horizontal, vertical
 Small % of population
 Pathological if > 1 plane and > 1 direction
 Dilantin
 Hemorrhages or tumors of inner ear (?)
 Hx--?????
Cover test
 Have patient look at distant object
 Shine light and look for corneal reflection
 Should be in same spot on both eyes
 Cover one eye, then uncover
 Does covered eye move outward?
 If uncovered eye moves—was not in focus
 Moves outward—was convergent before
 Moves inward—was divergent before
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Convergent strabismus—esotropia
Divergent strabismus—exotropia
Paralytic strabismus (severe weakness)—see text
Amblyopia (lazy eye)
 Loss of visual acuity secondary to suppression (in children)
Range of motion (full)
 All the way to extremes of eye
 May see it with nystagmus
 Slow in one direction, quick in another
Visual acuity
 Do before fundoscopic exam
 Recorded as a fraction
 Numerator = distance from chart
 Denominator = distance normal eye can see
 The smaller the fraction, the worse the distant vision
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PHYS DX
Distant vision (Snellen chart)
 Pt stands ~ 20 feet away
 Cover 1 eye
 Instruct patient to read smallest line possible
 If patient cannot the 20/200 line (top line), have them move closer
Decreased distant vision = myopia
Decreased near vision = hyperopia
Decreased near vision and > 45 years old = presbyopia
Near vision
 Test each eye separately
 Hand held card ~ 14” from eyes
 Read smallest line possible
Children
 Use and “E” chart
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 since may be dealing with young child
 ask which way prongs are pointing
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If patient gets all correct for a line except one: 20/50 -1
If patient gets 3 out of 6 correct: 20/20 +3
When do we consider there’s a problem?
 Consult an ophthalmologist
 Check the fundus
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US—legal blindness  20/200 or less after correction or decrease of field of vision of 20 or less
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If vision is 20/40  needs 2 diopters
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For decreased vision use finger counting or hand waving
Visual fields
 Confrontation method (to evaluate peripheral vision)
 Stand in front or in back of patient
 At what point can patient first see object (or last see object)
 Have patient cover one eye and look straight ahead
 Subjective since patient could have moved eyes
Perimeter method—stimulates retina
Normal angles
 Superior--50
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PHYS DX
Medial--60
Inferior--70
Lateral--90
Visual Pathways (text
Table 7-2)
Visual field defects
 May see an angle of decreased vision
 Remember—get inversion and rotation as image goes to cortex
 Which field is not seen?
 Caused by
 Occlusion of branch of central retinal artery
 Superior artery  inferior aspect
 Inferior artery  superior aspect
 Complete lesion of optic nerve  blind eye
 Lesion of optic chiasm  temporal fields (bitemporal hemianopsia)
 Optic tract  medial fibers from one side and temporal fibers from other side
 Ex. –lesion on right  right nasal visual field and left temporal visual field =
left homonymous hemianopsia
 Partial lesions—quadrant defects
Ophthalmoscope
 Used to view interior anatomy
 Two dials—light apertures and diopters
 Light apertures and filters
 Small—undilated pupil
 Large—dilated pupil
 Red free filter (green)—excludes red light
Exam
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View fundus
Optic disc
 Bring into focus
 If patient hyperopic or presbyopic—use black numbers
 If patient myopia—use red or minus numbers
Blood vessels
Macula and fovea centralis
Periphery of fundus
Anterior structures
Using scope
 Darken the room and turn on scope
 Use right hand for right eye of patient
 Lens diopter set on zero or to doctor’s vision
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PHYS DX
Instruct patient to look at distant object over your shoulder ~ 20 angle superior/lateral
From a position 6-15 “ away and 15 lateral to pt’s line of vision, shine light beam on
pupil
Note orange-red glow—“red reflex”
 Absent—wrong positioning
 Opacities—cataracts, detached retina, hemorrhage
Follow red reflex in toward patient ~ 1=2” from eye; will se a reddish/orange to a dark
pink retina and a round central disc
Normal optic disc
 1.5 – 2mm if focused properly
 may appear larger in myopia and slightly smaller with presbyopia
 normally round
 pale pink or whitish or grayish
 pale or gray—optic atrophy
 red—papilledema