Evaluation of Eye Complaints

3 chambers: anterior, posterior, vitreous

3 layers:

1) sclera: outer coating of eye, white, fibrous

2) choroid: bed of blood vessels, right under retina

3) retina: sensory portion (photoreceptors, nerves, etc.)

What are the 3 chambers and 3 layers of the eye?

retina, macula

optic nerve (CN II)

occipital lobe

Light enters the eye through the cornea, pupil, iris, and lens.

Light waves land on the ____________, primarily the central area (aka the _____________).

Light impulses are transmitted to electrical signals and sent along the _______________________.

The ____________________ of the brain interceptors these signals as visual images.

CN II

Which cranial nerve?:

- sensory impulses for sight

CN III

Which cranial nerve?:

- raises eyelid, rotates eye, adjusts amount of light (constricts pupil)

CN IV

Which cranial nerve?:

- superior oblique m

CN V

Which cranial nerve?:

- sensory (touch, pain) to eye

CN VI

Which cranial nerve?:

- lateral rectus m

CN VII

Which cranial nerve?:

- closes the eye

- hyperemia of vessels (conjunctival, ciliary, episcleral vessels)

- subconjunctival hemorrhage

What are potential causes of redness?

- eye pain

- foreign body sensation

- photophobia

- scratching/burning

- watering

What are potential causes of ocular discomfort?

- eyestrain: refractive error, inadequate lighting, latent ocular deviation

- HA: rarely d/t ocular disorders

What are potential causes of eyestrain and HA?

- purulent: bacterial infxn of conjunctiva, cornea, or lacrimal sac

- watery: viral conjunctivitis or keratitis, allergic conjunctivitis

What are potential causes of conjunctival discharge?

- blurred vision:

- monocular field loss: dz of retina or optic nerve

- bitemporal field loss: lesions of optic chiasm (usually pituitary tumor)

What are potential causes of visual loss?

- visual impairment: usually d/t uncorrected refractive error

- blindness: usually d/t cataract

What are potential causes of visual impairment and blindness?

75%

What percentage of vision loss is treatable or preventable?

acquired ocular misalignment, refractive error, lens opacities

What are potential causes of diplopia?

floaters: usually d/t benign vitreous opacities; maybe posterior vitreous detachment

flashing lights: ocular migraine; if sudden, retinal tear or detachment

What are potential causes of spots and flashing lights?

direct, consensual

The light rxn:

a light beam shining onto one retina causes pupillary constriction in both that eye (_______________ pupillary response) and in the opposite eye (______________ pupillary response).

1) pupils constrict when a person shifts gaze from a far object to a near one

2) eyes convergence

3) lens accommodation - inc convexity of lenses d/t contraction of ciliary mm

What should happen in the near pupillary response test?

strabismus / tropia

condition where eyes are not properly aligned with one another, resulting in one eye looking straight ahead while the other may turn inward (esotropia), outward (exotropia), upward (hypertropia), or downward (hypotropia)

strabismus / tropia

deviated or "crossed eye"

object being viewed is not projected simultaneously on the fovea of each eye

lack of coordination btwn EOMs

2 main causes: 1) disorder of brain or 2) disorder of mm

esotropia

imbalance caused by ocular muscle tone

medial gaze deviation

cross-eyed

exotropia

imbalance caused by ocular muscle tone

lateral gaze deviation

wall-eyed

cover/uncover test

How do we diagnose strabismus?

amblyopia

impaired vision in excess of that explained by structural, ocular, or visual pathway disease

severe loss of vision can occur in the affected eye if not detected and treated before age 8

sometimes called "lazy eye"

strabismus

what is the most common cause of amblyopia?

anisocoria

pupils uneven on visual inspection

small one

sympathetic system

which pupil is ABN is anisocoria is greater in the dark than light? which system does this affect?

large one

parasympathetic system

which pupil is ABN if anisocoria is greater in light than dark? which system does this affect?

marcus gunn pupil

aka relative afferent pupillary defect (RAPD)

pupils respond differently to light shown in 1 eye at a time (constrict less.. appear to dilate when light is swung from unaffected eye to affected eye)

d/t optic nerve lesion prior to optic chiasm

anisocoria absent

horner's syndrome

lesion in sympathetic pathway

sympathetic, ptosis, miosis, anhidrosis

NL rxn to light and accommodation

Adie's tonic pupil

parasympathetic pathway disrupted

eye is dilated, constricts poorly to light

constricts to near, but sluggishly

anisocoria present

argyll robertson pupil

neurosyphilis

small pupils that don't respond to light, but constrict with accommodation

refractive error

occur when the shape of the eye prevents light from focusing directly on the retina

emmetropia

NL eyes

vision is perfect

parallel light falls directly on the retina

myopia

near-sighted

see nearby objects clearly but distant objects appear blurred

eyeball is too long or cornea is too steep

images are focused in the vitreous inside the eye rather than on the retina (back of the eye)

commonly corrected with corrective lenses

refractive surgery - LASIK

hyperopia

far-sighted

eyeball is too short OR lens cannot become round enough

light rays focus behind the retina

inability to focus on near objects

presbyopia

lens becomes hardened with age

less pliable

patient loses ability to make lens rounder

progressive decrease in near vision

decrease in accommodation

bifocals needed

astigmatism

error in focusing ability of eye

light is not uniformly focused in all direction

cornea is not perfectly spherical and can cause the image to focus in front or behind the retina or both

anopsia

complete blindness in one or both eyes

hemianopsia

decrease vision in 1/2 of visual field

quadrantanopia

decreased vision in 1/4 of visual field

anopsia

complete loss of vision

total blindness in one or both eyes

lesion location: retina or optic nerve distal to chiasm (monocular); optic chiasm (binocular)

bitemporal hemianopsia

loss of the outer half of the visual field

cannot see objects on the sides

lesion location: optic chiasm (e.g., pituitary tumor)

homonymous hemianopsia

loss of the same half of the visual field

same side loss in both eyes (left or right)

lesion location: optic tract or occipital lobe

quadrantanopia

loss of vision in one quadrant

loss of vision in 1/4 of the field

lesion location: temporal lobe (superior quadrantanopia); parietal lobe (inferior quadrantanopia)

- don't prescribe numbing drops for pts to use at home

- toxic to corneal epithelium, may result in further injury to eye without knowing it

Precautions in use of local anesthetics.

occasionally may lead to PACG (always first check to see if pt has a shallow chamber via oblique illumination)

Precautions in pupillary dilation.

- repeated use of topical steroid drops may lead to herpes/fungal keratitis, POAG, cataract formation

- can use topical NSAID as anti-inflammatory instead

Precautions in corticosteroid therapy.

- open bottles of eye meds subject to contamination (esp pseudomonas) -> esp fluorescein -> use single-use filter paper strips in clinic

- check expiration dates, and be aware of how long bottle has been open -> if has preservatives, toss after 4 weeks -> if preservative-free, refrigerate, toss after 1 week

Precautions in contaminated eye medications.

local toxic or hypersensitivity rxns to the med or the preservatives can occur, esp if inadequate tear production

Precautions in toxic and hypersensitivity rxns to topical therapy.

- systemic absorption of certain topical drops may occur, use caution if there is a systemic medical contraindication to the drug

- nasolacrimal occlusion can help minimize systemic absorption

Precautions in systemic effects of ocular drugs.