Transcript Eye care basics and optical options

Eye care basics
and optical options
Rick Smith
&
Sam Powdrill
Eye Anatomy
Visual Image
Components of Vision
The External Eye
The Skull
Bones of the Orbit
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Frontal
Zygoma
Ethmoid
Maxilla
Sphenoid
The Lacrimal System
The tear film
• Lipid layer
• Aqueous layer
• Mucus layer
The Eyelids
Vessels and
Muscles
of the
Eyelids
Extrinsic Eye Muscles
Extrinsic muscles with
innervation
The Globe
• Anterior chamber
aqueous
• Iris
• Lens
• Posterior
chamber vitreous
• Optic nerve
Layers of the eye
• Protective
• Vascular
• Visual
Protective Layer
• Sclera
• Cornea
Vascular layer
• Iris
• Ciliary body
• Choroid
Angle of the Eye
Visual Layer
• The retina
• Optic nerve
Central Retina
Optic Nerve (II)
Visual pathway
Optic Nerve (II) – Visual pathway
Refraction
Prism
Converging
diverging
Lens Power
• Measured in diopters
• One diopter lens focuses at 1 meter
Lens power =
100 cm
focal length
focal length =
100 cm
Lens power
Refractive errors
• Nearsighted – myopia
• Farsighted – hyperopia
• Astigmatism
• Presbyopia
Refraction
• Convex lens
• Concave lens
• Accommodation
• Refractive error
Correction of Refractive Errors
• Pinhole
• Myopia
• Hypermetropia
• Astigmatism
Exam of the Eye
Pathways of
Blindness
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Corneal
Anterior chamber
Lens
Vitreous
Retina
Optic nerve
Occipital
Functional
Instruments needed to examine the
eye
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Visual acuity chart
Flashlight
Ophthalmoscope
Tonometer
Simple loupe
Measure Visual acuity
The vital sign of the eye
• Distance vision
• Near vision
• Peripheral vision
• Central vision
• Color vision
Snellen
charts
Pinhole
eliminates
the
refractive
error
Visual acuity
• Cover the eye with
the palm of the
hand
• Test the eyes
separately then
together
• Point to the letters
clearly
• Use a random
sequence
Recording Visual acuity
20/20
Upper number = distance in feet from the
patient to the chart
Lower number = distance in feet at which
a person with excellent vision
would see the same letter
Examples
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20/40
20 /400
20/15
10/50
CF 10ft
HM
LP
NLP
Central vision
• Test for loss of central vision - macula
• Amsler grid
• Abnormal in macular degeneration
Amsler grid
Color vision
• Check for red / green color blindness
• Ishihara chart
• Color comparison method with a red object
• Color blindness is an X linked genetic disorder
that most often affects males.
Ishihara chart
Tonometry
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Schiotz
Applanation
Air puff
tonopen
Normal
is
10 to 20
mmHg
Extraocular Muscles
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Six Cardinal eye movements
Corneal light reflex position
Nystagmus
Cover - uncover test
Convergence
Peripheral vision
Testing the visual field
• Confrontation method – compares the
examiner’s visual field with the patient’s
• Automated – done in optometrist’s or
ophthalmologist’s office
• Abnormal in glaucoma
Visual fields by confrontation
Eyelids
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Inspect
Symmetry – skin creases
Opening and closing completely
Eyelash position
Ptosis
Tremor or fasciculations
Swelling or infection
Flakiness
cataract
• Ophthlmoscope
set on +4
• Shadows against
Red reflex
Direct light vs Coaxial light on the lens
Eyelids
Palpate
• Eyelids for nodules
• Intraocular pressure
Evert upper and lower lids and inspect
• Color
• Discharge
• Lacrimal system
Conjunctiva and Sclera
Inspect
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Redness
Vessels
Growths or lesions, foreign bodies
Proptosis
enophthalmos
Cornea
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Inspect
Clarity – scars obscure part of the iris.
Light reflex – reflex is scattered in edema
Corneal sensitivity
Arcus
Depth of anterior chamber – iris shadow
Abrasions or foreign bodies – use fluorescein stain
with blue light to examine the cornea for defects
Iris and pupil
Inspect Iris
• Color
• Angle
• lesions
Inspect Pupil
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Size
Shape
Reaction to light
Reaction to near
Consensual response
PERRLA
Ophthalmoscope exam
Lens clarity – lens opacity is a cataract
Red reflex – ophthlmoscope set on + 4
Vitreous clarity – floaters, sclerotic bands
Retinal color and background
Retinal vessels – hemhorrage, cotton wool spots,
AV nicking, neovascularization,
Optic disc – cup/disc ratio
Optic nerve head – papilledema, cupping or
atrophy
Macula for drusen or changes
Retina
Retina