Eye care basics and optical options

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Eye care basicsand optical options

• Rick Smith
• Sam Powdrill

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Eye Anatomy
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Visual Image
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Components of Vision
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The External Eye
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The Skull
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Bones of the Orbit

• Frontal
• Zygoma
• Ethmoid
• Maxilla
• Sphenoid

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The Lacrimal System

• The tear film
• Lipid layer
• Aqueous layer
• Mucus layer

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The Eyelids
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Vessels andMusclesof the Eyelids
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Extrinsic Eye Muscles
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Extrinsic muscles with innervation
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The Globe

• Anterior chamber aqueous
• Iris
• Lens
• Posterior chamber vitreous
• Optic nerve

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Layers of the eye

• Protective
• Vascular
• Visual

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Protective Layer

• Sclera
• Cornea

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Vascular layer

• Iris
• Ciliary body
• Choroid

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Angle of the Eye
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Visual Layer

• The retina
• Optic nerve

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Central Retina
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Optic Nerve (II) Visual pathway
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Optic Nerve (II) Visual pathway
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Refraction
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Prism
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Converging
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diverging
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Lens Power

• Measured in diopters
• One diopter lens focuses at 1 meter
• Lens power 100 cm
• focal length
• focal length 100 cm
• Lens power

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Refractive errors

• Nearsighted myopia
• Farsighted hyperopia
• Astigmatism
• Presbyopia

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Refraction

• Convex lens
• Concave lens
• Accommodation
• Refractive error

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Correction of Refractive Errors

• Pinhole
• Myopia
• Hypermetropia
• Astigmatism

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Exam of the Eye
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Eye Exam
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Pathways of Blindness

• Corneal
• Anterior chamber
• Lens
• Vitreous
• Retina
• Optic nerve
• Occipital
• Functional

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Instruments needed to examine the eye

1. Visual acuity chart
2. Flashlight
3. Ophthalmoscope
4. Tonometer
5. Simple loupe

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Measure Visual acuity

• The vital sign of the eye
• Distance vision
• Near vision
• Peripheral vision
• Central vision
• Color vision

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Snellen charts
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Pinholeeliminates the refractive error
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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

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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

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Examples

• 20/40
• 20 /400
• 20/15
• 10/50
• CF 10ft
• HM
• LP
• NLP

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Central vision

• Test for loss of central vision - macula
• Amsler grid
• Abnormal in macular degeneration

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Amsler grid
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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.

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Ishihara chart
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Tonometry

• Schiotz
• Applanation
• Air puff
• tonopen

Normal is 10 to 20 mmHg
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Extraocular Muscles

• Six Cardinal eye movements
• Corneal light reflex position
• Nystagmus
• Cover - uncover test
• Convergence

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Peripheral vision

• Testing the visual field
• Confrontation method compares the examiners
  visual field with the patients
• Automated done in optometrists or
  ophthalmologists office
• Abnormal in glaucoma

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Visual fields by confrontation
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Eyelids

• Inspect
• Symmetry skin creases
• Opening and closing completely
• Eyelash position
• Ptosis
• Tremor or fasciculations
• Swelling or infection
• Flakiness

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cataract

• Ophthlmoscope set on 4
• Shadows against Red reflex

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Direct light vs Coaxial light on the lens
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Eyelids

• Palpate
• Eyelids for nodules
• Intraocular pressure
• Evert upper and lower lids and inspect
• Color
• Discharge
• Lacrimal system

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Conjunctiva and Sclera

• Inspect
• Redness
• Vessels
• Growths or lesions, foreign bodies
• Proptosis
• enophthalmos

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Cornea

• 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

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Iris and pupil

• Inspect Iris
• Color
• Angle
• lesions
• Inspect Pupil
• Size
• Shape
• Reaction to light
• Reaction to near
• Consensual response
• PERRLA
  

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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

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Retina
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Retina
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Retina
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Retina
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