UNIT 1: Anatomy & Physiology of The Eye Flashcards
What makes the eye like a Camera?
-Automatic focus from one inch to several miles away.
-3D images.
-Control the amount of light to the eye.
-Contrast awareness.
-Transmit a coded message to “computer”.
What are the parts of the human seeing system?
-Two sets of lenses (gather and focus images)
-Two sensing devices (detect light, send signals)
-A brain (interpret signals)
Marginal Blepharitis
-Lid margins have build up of bacteria
-Dandruff of eyelids
-Sore, red lids
-Use socially medicated soap to cure
Cataracts (Senile)
-Most common
-The lens, due to age, becomes opaque and dense.
-There is no cure, only solution is cataract extraction.
Causes and Symptoms of Cataracts (Senile)
-Increasingly blurred vision and distortion.
-Distance visio0n deteriorates, while near vision may improve due to increased lens convexity.
Cataracts (Traumatic)
-Most commonly caused by a foreign body injury to the lens, or a blunt trauma to the eyeball.
-BB gun frequent cause.
-Other causes: Arrows, sticks, rocks, over exposure to x-rays & radio active waves.
Cataracts (Traumatic) Continued…
-The lens becomes opaque quickly after injury due to entry of aqueous, and sometime vitreous humor into the lens capsule.
-The cataract may be removed at the same time the foreign body is removed.
Cataract (Congenital)
-Often caused if the mother has had maternal rubella (Measles) in the first trimester of pregnancy.
-Parent notices that the child does not see well during first few months of life. The pupil may appear white.
-Should be removed ASAP to avoid amblyopia in both eyes.
Types of cataract surgery (Intracapsular Extraction)
Removal of the lens in total, capsule and all, though a 140-160 degree limbal incision.
Types of cataract surgery (Extracapsular)
A limbal incision is made once more, leaving the posterior capsule behind.
Types of cataract surgery (Phacoemulsification)
Lens and capsule fragmented and sucked out by ultrasonic vibrations.
Conjunctivitis (Signs and Symptoms)
-The most common eye disease in the western hemisphere.
-Redness
-Tearing
-Foreign body sensation
-Scratching, burning
-Sensation of fullness around the eyes
-Itching
-Photophobia
Glaucoma
-IOP too high, causing too much pressure on the optic nerve.
-Up to 24mm of mercury is normal.
-Approximately 50K people in the USA are blind due to glaucoma.
-Incidence in people over 40 is 1.5%.
-Common in A.A people (15x that of Caucasians)
Glaucoma Continued..
-Once detected, we can stop the progression with miotics, however, we cannot repair any damage done.
-The only symptom is impairment of vision, which is too late to correct.
-Hereditary and is checked with tonometry.
Macular Degeneration
-Exact cause unknown
-Age related (ARMD)
-Race, Gender, Family History, Smoking