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CLINICAL PERSPECTIVESSTRUCTURES AROUND THE GLOBE
Orbit- provides a safe place for the eyeballeyelids- closes light off of eye, protects, distributes tearstears- lubricates & protectslacrimal system- distributes tearsconjunctiva- covers sclera and inner surface of eyelidsorbital septum- bone covering top of orbiteyebrow- covers orbital septum, protects eye from sweat
Extraocular Muscles
• Superior & Inferior Recti
• Medial & Lateral Recti
• Superior & Inferior Obliques
Eyelids & eyelashes
• meibomian glands- oil glands
Conjunctiva
• sclera- white fibrous covering of eyeball
• limbus- point where sclera and cornea meet
Lacrimal Apparatus
• puncta- inner margin of the upper & lower lids
• caniliculi- passages to sacs & ducts
• lacrimal sac- contains some tears
• nasolacrimal duct- drains tears into nose
Eye Divided Into Two Parts
• Anterior Segment– aqueous humor– pupil– Iris– lens
• Posterior Segment– vitreous humor– retina– optic nerve
Cornea• clear, avascular window of the eye, most
refractive power
Anterior Segment
• aqueous humor• trabecular meshwork• canal of Schlemm • ciliary process• lens
Pupil & Iris
• Pupil- adjusts light
• Iris- pigmented muscular ring
Structures In the Globe
• 3 Main Structures: – protective outer layer– vascular inner layer– sensory retina
Vascular Inner Layer
• Uveal tract
• Ciliary body
• Choroid
Sensory Layer
• Central Retina– Macula & fovea contain mostly cones– Optic disk
• Peripheral Retina– Contains mostly rods
Transmission of Visible Information to the Brain
• Light energy from environment to chemical energy in retina to electrical energy in optic nerve & synapses to chemical energy in nerve cells
Relationship of Sight to Vision
• Images from eye structures must be interpreted in the visual cortex for sight to occur
• The eyes and associated structures must be normal in structure & function.
• The neurological pathways from the retina & optic nerve to the visual cortex must be in tact.
• The brain must be capable of interpreting the information received.
MEDICAL EYE REPORT
• Name• Sex• Age• Family Medical Hx• General Medical Hx• Surgical Hx• Medications• Ophthalmic complaint
Eye Care Professionals• Optometric technicians, ophthalmic
technicians• Vision Rehabilitation practitioner• Teacher of Visually Impaired• D.O.- doctor of optometry, doctor of
ophthalmology, low vision specialist• M.D.- ophthalmologist• Specialist- did fellowship in specialty,
FACS• optician
VISUAL ACUITIES
• Autorefractor
• Lensometer
• Snellen chart (distance)
• Checking distance each eye using an occluder
• Jaeger near vision chart
• Ishihara- color vision charts
• Titmus fly
• Amsler grid
External Examination
• LLL- Lids, lens, lacrimal system
CAUSES & FUNCTIONAL IMPLICATIONS OF VISUAL
IMPAIRMENT
• PERL- Pupils equal & reactive to light
•
• MM- Muscular motility
• Eye Muscle Balance
Cornea & Anterior Segment
• Ophthane- numbs eye
• Midriatic- dilates pupil
• Cycloplegic- relaxes lens
• Tonometer- measures pressure– FP- finger pressure– Air puff– Contact
• Keratometer- measurement of corneal thickness
• Goniometer- measures angle of anterior segment (risk factors for glaucoma)
• Slit lamp
• Direct ophthalmoscope
Undilated versus Dilated Pupil
• Indirect ophthalmoscope
Normal Fundus
• Phoropter
Functional & Visual Efficiency Testing
• Behavioral
• Electrophysiological
• Subjective
Behavioral
• OKN (optokinetic nystagmus)- cortical
• PLT (preferential looking test)- Teller acuities
• Chromatic luminance- contrast sensitivity
• Tracking a toy or light
Electrophysiological
• Fundus photos & OCT
• VER- visual evoked response- visual pathways, cortical function
• ERG- electroretinogram (cone & rod function)
• EOG- electrooculogram (measures charge & potentials of eyes)
Subjective
• Acuity– Lea charts– Snellen– Tumbling E– Amsler grid
• CSF- contrast sensitivity function• Flicker fusion macular & foveal function• Color- Ishihara & Farnsworth• Visual fields
– Confrontation– Ganzfeld globe– computerized
Visual Efficiency Testing
• ISAVE
• Program to Improve Visual Efficency (Barraga)
• Conditions That Result In Low Visual Acuity
Ocular Muscle Disorders-
• eyes that are not in proper alignment
Strabismus & Amblyopia
amblyopia- a reduction in visual acuity due to non-use of the eye
• tropia- marked deviation of an eye• esotropia- turning in of one or both eyes
• exotropia- turning out of one or both eyes
• hypertropia- turning up of one or both eyes• hypotropia- turning down of one or both eyes• phoria- tendency of eye to deviate, particularly when
fatigued or fusion broken
Nystagmus
• Involuntary, rhythmical repeated movement of one or both eyes in a horizontal, vertical or pendular motion– null point- point of least nystagmus & best
vision– pendular nystagmus- up-and-down
movements of equal speed, amplitude & duration
– jerk nystagmus- slower movement in one direction