Anterior Eye diseases

eye movements

are important for several aspects of vision, including visual field coverage, stabilization, and object tracking

Strabismus

”Cross-eyed”
• Weakening or misalignment of the eye’s muscles.

• more of a motor problem than a sensory problem

*may lead to Amblyopia

Amblyopia

”Lazy eye”
• The weakening of one eye’s input into the brain.
• Without as much sensory input the position of the weaker eye will
wander. This will lead to misalignment.

• more of a sensory problem than a motor problem

Strabismus

Double vision, loss of depth perception is a characteristic of . . .

Amblyopia

blurred vision is a symptom of . . .

Genetics (children), Stroke, Brain tumor

what are causes of Strabismus?

Surgery, Corrective Lenses, Eye Exercises, Botox

what are treatment options for Strabismus?

Corrective lenses, cataract surgery, deprivation of “strong” eye.

what are treatment options for Amblyopia?

high refractive error, deprivation (opacity of corneal or lens) — of one eye

what are possible causes of Amblyopia?

corneal abrasion

any physical or chemical injury to the cornea

Keratitis

Both bacteria and other microbes can infect the cornea and conjunctiva surrounding the sclera

a bacteria that can infect the cornea with improper contact lens use, leading to keratitis

what is Acanthamoeba?

Keratoconus

Corneal thinning which changes in how light is refracted into the eye leading to blurry vision and bulging of the eye

cornea transplants

• Keratoplasty – transplant from donor tissue

• Keratoprosthesis –transplant with prosthetic cornea

In rare and severe cases, ______ can be used to replace the damage tissue

Coloboma

misshapen iris caused by developmental errors

constriction: parasympathetic

dilation: sympathetic

what nervous system controls pupil constriction and dilation?

1) Bud off the forebrain
2) Begin fold into a cup shape
3) Seal the cup shape

*The choroid fissure (optic fissure) must seal properly for normal eye development.

what are 3 stages of early eye development?

- Genetic, inheritance
- Alcohol exposure during pregnancy

what are causes of coloboma?

- Contact lenses, cosmetic
- Amblyopia correction; eye patch

what are treatment options for coloboma?

No, they can affect the eyelid, retina, lens, etc.

do colobomas only affect the iris?

1) The cells in the central lens do not have a nuclei or organelles.
2) The cells in the central lens consist of a structural protein called crystalline

what are 2 key reasons that the lens in transparent?

cataracts

a clouding of the lens, reducing transparent, and reducing vision

• Blurry vision
• Difficult with vision in dim light
• Halos around lights

what are symptoms of cataracts?

50%

*age is the major contributor to cataracts

___% of adults over the age of 75 have cataracts

UV light, diabetes, smoking, radiation, chemo, genetics

what are other risk factors that contribute to cataracts?

it is normally soluble but aggregates together during cataract formation

what happens to Crystallin during cataract formation?

cataract removal surgery

1) Remove (suction) the old lens in small pieces.
2) Replace with new artificial intraocular lens (IOL).

what is the only treatment for cataracts?

flexed (push lens to be thicker)

when viewing things close-up, ciliary muscles are _____

relaxed (pull lens to be thinner)

when viewing things far away, ciliary muscles are _____

Myopia (Nearsightedness)

refractive error that makes far-away objects look blurry

Hyperopia (Farsightedness)

refractive error that makes nearby objects look blurry

Astigmatism

refractive error that can make far-away and nearby objects look blurry, or cause double-vision

Presbyopia

refractive error that makes it hard for middle aged and older adults to see things up close

the focal point of light lands short of the retina.

• Elongation of the eye.
• Incorrect cornea curvature.
• Defects in lens optics

what error happens in myopia?

the focal point of light lands beyond of the retina

• Shortening of the eye.
• Incorrect cornea curvature.
• Defects in lens optics

what error happens in hyperopia?

multiple focal points are projected to the retina

• Irregular cornea shape.
• Lens aberrations

*can be blurry horizontally OR vertically

what error happens in astigmatism?

the lens becomes less flexible with age

• cannot be easily rounded to focus on objects close-up

why does presbyopia occur in most people?