Ch 15. Eyes Flashcards
What 3 cranial nerves move the eye
III, IV. and VI (3,4,6)
III- Oculomotor
IV- Trochlear
VI- Abducens
List the 6 Extraocular muscles
Superior rectus Inferior rectus Lateral rectus Medial rectus Superior oblique Inferior oblique
Outer Layer: sclera
Sclera – tough protective white covering that is continuous anteriorly with the smooth transparent cornea.
Cornea covers the iris and pupil. Corneal reflex occurs when you touch a wisp of cotton to the cornea. Cranial nerve V and V11 innervates this reflex (blink)
Middle Layer: vascular choroid
Ciliary body and iris Pupil Lens Anterior chamber Posterior chamber
The middle area contains the choroid, which has dark pigmentation to prevent light from reflecting internally and which is highly vascular to deliver blood to the retina.
The choroid is continuous with the ciliary body and the iris. The ciliary body controls the thickness of the lens; The iris serves as a diaphragm, varying the opening at its centre; and the pupil controls the amount of light admitted onto t the retina.
The lens, which divides the eye into the anterior and posterior segments, is a transparent structure located behind the pupil. The lens keeps viewed objects in continuous focus on the retina.
The muscle fibres of the iris contract and dilate the pupil.
Parasympathetic ( cranial nerve 3) constricts the pupil and sympathetic system dilates it
Inner Layer: Retnia
Optic disc
Retinal vessels
Macula
Fovea centralis
- The inner layer contains the retina, which is the visual receptive layer of the eye. In the retina, light waves are changed into nerve impulses.
How does the image of the world appear on the retina (it’s orientation)
upside down and reversed
Older adults vision problems - 5 possible
Presbyopia Macular degeneration Cataracts Glaucoma Diabetic retinopathy
Risk factors of glaccoma
Age > 60 years African descent Female Increased intraocular pressure Family history Steroid use Decreased central corneal thickness Hypertension Eye injury Severe myopia Diabetes Use of certain medications
Subjective Data for an eye exam
- Vision difficulty (decreased acuity, blurring, blind spots)
- Pain
- Strabismus, diplopia
- Redness, swelling
- Watering, discharge
- History of ocular problems
- Glaucoma
- Glasses or contact lenses
- Self-care behaviours
- Medications
- Vision loss
Tests for Central visual acuity
Snellen eye chart
Near vision
Tests for Visual fields
Confrontation test
Tests for Extraocular muscle function—Inspect
- Corneal light reflex (Hirschberg’s test)
- Cover–uncover test
- Diagnostic positions test
How to test External ocular structures
Inspect: General Eyebrows Eyelids and lashes Eyeballs Conjunctiva and sclera Eversion of the upper lid Lacrimal apparatus
Inspect the Ocular Fundus
Ophthalmoscope
Darken the room to help dilate the pupil
Have patient stare straight ahead
Check for the Red Reflex
