ePathoPlusPage

Eye and Ear

Outline

EYE
    A. Disorders of optic globe and supporting structures
        1. exopthalmous (protruding of eyeball) and enopthlamous
            (sunken eyeball)

        2. eyelid (palpebrae)
            a. inflammation = blephoritis, two types
                1. seborrheic
                2. staphylococcal

            b. infection of sebaceous gland = sty (hordeolum)

            c. ptosis- drooping of upper eyelid sufficient to cause interference
                with light path, caused by weakness of levator palpebrae
                superior muscle

        3. conjunctivitis
            a. allergic
            b. bacterial- typically a copious purulent drainage

            c. viral, common cause adenovirus type 3, may also be
                caused by herpes simplex virus

            d. chlamydia- frequently acquired from swimming pools, birth
                canal infection

B. Glaucoma    (increased pressure of aqueous humor)
    1. closed angle glaucoma (narrow angle)
        a. anterior chamber is narrow and outflow is impaired when
            iris thickens as a result of pupil dilation

        b. symptoms- related to sudden intermittent changes in intraocular
            pressure due to extensive and prolonged pupil dilation, include
            ocular pain, blurred vision, headache

        c. usually due to an inherited anatomic defect that causes a narrow
            anterior chamber

    2. open angle glaucoma (wide angle)
        a. 90% of all cases of glaucoma
        b. increase in intraocular pressure due to abnormality in trabecular
            meshwork that impairs flow of aqueous humor between anterior
            chamber and Canal of Schlemm

        c. symptoms- usually asymptomatic, gradual but progressive
            loss of visual field

C. Cataracts- lens opacity that interferes with transmission of light to retina
       1. Classification
            a. congenital (may be hereditary, or due to measles
                infection of mother during 1st trimester)

            b. traumatic
            c. senile (N.B. at 80 yrs of age  85% of all people have some
                clouding of lens)

            d. cataracts due to metabolic and toxic agents
                1. disorders of CHO metabolism as seen in diabetics
                    can lead to cataracts

    2. symptoms- gradual decline in visual acuity

D. Papilledema
        1. increased intracranial pressure can impinge on central retinal
            artery- increases capillary permeability - edema of optic papilla

        2. unresolved it can lead to destruction of optic nerve axons and
            blindness

E. Retrolental fibroplasia
        1. bilateral retinal dx of premature infants who must be given high
            doses of oxygen during first 10 days

        2. during period of blood vessel immaturity the bv reaction to
            increased oxygen tension is vasoconstriction, obliteration
            and suspension of normal vessel growth

        3. once blindness has developed, no tx will restore sight

F. Vascular Retinopathies
    1. caused by microaneurysms
    2. caused by neovascularizations (formation of new blood
        vessels which tend to be fragile, leak protein and tend to bleed0

    3. caused by atherosclerosis
    4. caused by retinal artery occlusion- complete occlusion
        results in sudden unilateral blindness (anopsia)    

    5. caused by central vein occlusion- usually unilateral, results in
        rapid detrioration of visual acuity. Often secondary to HTN, DM,
        sickle cell dx

    6. diabetic retinopathies
            a. background  - confined to the retina, involves thickening of
                capillary walls and microaneurysm formation- rupture-
                bleeding into retina

            b. proliferative- due to neovascularization of vitreous- bleeding into
                vitreous

    7. caused by HTN

G. Retinal detachment -

separation of the retina from underlying epithelium- loss of blood supply - loss of vision

H. Retinitis pigmentosa
    a. hereditary dx that causes slow degenerative changes in
        rods

    b. night blindness is first symptom

I. Strabismus (heteropsia or squint)
    a. any loss of binocular eye movement that results in loss of
        binocular eye alignment and focus of a visual image on
        corresponding points of both retinas

    b. two types
            1. paralytic- due to paresis (weakness) or plegia
                (paralysis) of one or more of the extraocular eye muscles
                    a.uncommon in children but accounts for nearly all cases of
                    adult strabismus
                    b. caused by CVA, tumor, inflammation, muscular dystrophy
                    c.in adults with previous normal vision causes diplopia

            2. nonparalytic
                a. causes are obscure
                b. most often monocular
                c. tx is important, if no tx may lead to amblyopia

EAR

A. Otitis Externa

B. Otitis media
    a. most common dx tx by pediatricians
    b. may be acute, subacute or chronic
    c. highest risk group= 6-36months of age because
        a. Eustachian tube is shorter, more horizontal

    d. complications
        1. persistent conductive hearing loss

        2. adhesive om

        3. tympanosclerosis

        4. perforated ear drum

        5. cholesteatoma (sac like mass containing silvery white
            debris of keratin (shed by squamous epithelial lining of
            eardrum)- lesion erodes surrounding tissue as it expands causing
            intracranial complications

        6. acute mastoiditis

   C. Vertigo (hallucination of motion)
            a. objective (person is stationary and environment seems
                in motion

            b. subjective - person is in motion and environment seems
                stationary
            c. note- not the same as dizziness (which is light headedness,
                fainting and unsteadiness)

    D. Motion sickness
            a. due to repeated, rhythmic stimulation of vestibular
                system
            b. symptoms- vertigo, malaise, n&v, autonomic
                (decreased BP, tachycardia, excessive sweating)

    E. Meniere's syndrome
        a. caused by an over accumulation of endolymph.

        b. symptoms- sudden attacks characterized by fluctuating levels of
            tiniitus, feelings of ear fullness, violent rotary vertigo, pallor,
            sweating, n&v, nystagmus, hearing loss

        c. etiology- allergy, adrenal pituitary insufficiency, trauma,
            hypothyroidism, idiopathic