CLINICAL MEDICINE OPTHALMOLOGY LATEST UPDATE
Emmetropia
A condition where the eye is in focus at a distance without accommodative effort
No refractive error is present
Eye with no visual defects
Hyperopia
(Farsightedness) parallel rays converge to focus behind the retina; the eye is t...
Emmetropia
A condition where the eye is in focus at a distance without accommodative effort
No refractive error is present
Eye with no visual defects
Hyperopia
(Farsightedness) parallel rays converge to focus behind the retina; the eye is too short
or weak to bring distance or near objects into focus without aid of accommodation
corrected with convex lenses
Can't see near
Myopia
(Near sightedness) parallel rays converge to focus in front of the retina; the eye is too
long or the refractive power is too great to bring distant objects into a clear focus
corrected with concave (minus) lens
Can't see far
Physiological: born with "normal" long eye; occurs as result of a correlation failure of
refraction components in the normal eye
Pathological: eye keeps growing, caused by excessive axial elongation that primarily
,involves the oraquatorial area and the posterior pole; more prone to retinal tears and
detachment (basically an excessive elongation of the eye, which stretches the retina)
Astigmatism
The refractive power of the eye is not equal in all meridians.
Without point focus- eye is incapable of forming a point focus
Simply put, the eye doesn't focus light evenly on the retina; distorted or blurred vision
Corrected with toric lenses
Presbyopia
The natural loss of accommodation due to thickening of the lens secondary to age
• Typically occurs after age 40
• Corrected with near reading prescription
Movement of the eye by the ocular muscles and their associated cranial
nerves
Oculomotor --> Superior Rectus, Medial Rectus, Inferior Rectus, Levator Palpebrae and
Inferior Oblique
Trochlear --> Superior Oblique
Lateral Rectus --> Abducens
Strabismus
When the eyes are not aligned together.
The imbalance can be horizontal or vertical
Exotropia: eye turns outward
,Esotropia: eye turns inward
Hypertropia: eye turns up
Hypotropia: eye turns down
Congenital vs Acquired Strabismus
Acquired: needs to be evaluated for etiology (neurologic vs vascular vs tumor)
Congenital: born with it; can cause amblyopia, in which the brain ignores input from the
deviated eye
Amblyopia
Lazy eye - Can be result of an early astigmatism that is not addressed; Occurs when an
eye can not attain
20/20 acuity even with corrective lenses
Generally classified as either strabismic(eye turn) or refractive(when there is a
significant
difference in the power of each eye.)
Important to intervene early in life(InfantSee
program)
Mydriasis
• Mydriasis: pupil dilation; excessive pupil dilation can be due to disease, trauma, and
drugs
- stimulation of the sympathetic branch causes pupil dilation
- Damage to or destimulation of the Parasympathetic branch (CN 3) can cause dilation
miosis
constriction of the pupil
- the normal response to light
, - excessive miosis associated with disease and drugs: opioids, anti-psychotics, and
trazadone.
- Parasympathetic stimulation leads to miosis, or
- Damage to Sympathetic Innervation causes miosis
**Horner's Syndrome: ptosis, miosis, and anhydrosis damage to sympathetic "arm"
The refractive function of the cornea and lens in correlation to how images are
produced
1. Light rays enter the eye through the cornea -> the cornea's refractive power bends
the light rays in such a way that they pass freely through the pupil opening in the center
of the iris through which light enters the eye
2. After passing through the iris, the light rays pass through the eye's natural crystalline
lens. This clear, flexible structure works like the lens in a camera, shortening and
lengthening its width in order to focus light rays properly
3. When light strikes the cornea, it bends -- or refracts -- the incoming light onto the
lens. The lens further refocuses that light onto the retina, a layer of light sensing cells
lining the back that starts the translation of light into vision. For you to see clearly, light
rays must be focused by the cornea and lens to fall precisely on the retina. The retina
converts the light rays into impulses that are sent through the optic nerve to the brain,
which interprets them as images
The difference between refraction and accommodation
Refraction: bending of light as it passes from one substance to another; bending of light
as it passes through the eye
From slides - (refractive error) problem with focusing of light on the retina due to shape
of the eye -> light is not bending properly when it passes through the lens of your eye
Accommodation: the ability of the eye to change its focus from distant to near objects
(and vice versa). This process is achieved by the lens changing its shape
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