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 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

Eye Exam

Pathways of Blindness Corneal Anterior chamber Lens Vitreous Retina Optic nerve Occipital Functional

Instruments needed to examine the eye Visual acuity chart Flashlight Ophthalmoscope Tonometer Simple loupe

The vital sign of the eye 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 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 Schiotz Applanation Air puff tonopen Normal is 10 to 20 mmHg

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

Testing the visual field 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 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 Redness Vessels Growths or lesions, foreign bodies Proptosis enophthalmos

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

Iris and pupil Inspect Iris Color Angle lesions Inspect Pupil 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

Retina

Retina