Download Disorders of Vision, Ocular Movement and

Disorders of Vision, Ocular
Movement and Hearing
Dr. Meg-angela Christi Amores
Vision
• Errors of refraction:
– Myopia – globe is too long, light rays come to a
focal point in front of the retina
– Hyperopia - the globe is too short, and hence a
converging lens is used to supplement the
refractive power of the eye
– Astigmatism - corneal surface is not perfectly
spherical, necessitating a cylindrical corrective
lens
– LASIK (laser in situ keratomileusis)-alter the
curvature of the cornea
Vision
• presbyopia develops as the lens within the eye
becomes unable to increase its refractive
power to accommodate upon near objects
– In middle age – older age
– Emmetropic patient must use reading glasses
– Hyperopic patient needs bifocals
– Myopic patient only need to remove glasses
Transient or Sudden Visual Loss
• Amaurosis Fugax
– transient ischemic attack of the retina
– transient monocular blindness
– occurs from an embolus that becomes stuck
within a retinal arteriole
• Optic Neuritis
– inflammatory disease of the optic nerve
– all patients experience a gradual recovery of vision
after a single episode
Chronic Visual Loss
• Cataract
– clouding of the lens sufficient to reduce vision
– Most develop slowly as a result of aging
– occurs more rapidly in patients with a history of
ocular trauma, uveitis, or diabetes mellitus
– detected by noting an impaired red reflex when
viewing light reflected from the fundus
– only treatment is surgical extraction
Chronic Visual Loss
• Glaucoma
– slowly progressive, insidious optic neuropathy,
usually associated with chronic elevation of
intraocular pressure; usually painless
– The mechanism whereby raised intraocular
pressure injures the optic nerve is not understood
– acute angle-closure glaucoma, the eye is red and
painful due to abrupt, severe elevation of
intraocular pressure
Ocular Movement
• Oculomotor Nerve (CN III)
– medial, inferior, and superior recti; inferior
oblique; levator palpebrae superioris; and the iris
sphincter
– ptosis, a dilated pupil, and leaves the eye "down
and out"
Ocular Movement
• Trochlear Nerve (CN IV)
– Innervate contralateral Superior Oblique
– hypertropia and excyclotorsion
– vertical diplopia is also exacerbated by tilting the
head toward the side with the muscle palsy, and
alleviated by tilting it away
Ocular Movement
• Abducens Nerve (CN VI)
– Lateral rectus muscle
– horizontal diplopia, worse on gaze to the side of
the lesion
Disorders of Hearing
• conductive hearing losses
– lesions in the auricle, external auditory canal, or
middle ear,
• sensorineural hearing losses
– lesions in the inner ear or eighth nerve
Conductive Hearing Loss
• obstruction of the external auditory canal by
cerumen, debris, and foreign bodies
• swelling of the lining of the canal
• atresia or neoplasms of the canal
• perforations of the tympanic membrane
• disruption of the ossicular chain
• Otosclerosis
• fluid, scarring, or neoplasms in the middle ear
Conductive Hearing loss
• Cholesteatoma
– stratified squamous epithelium in the middle ear
or mastoid
– slowly growing lesion that destroys bone and
normal ear tissue
– perforation of the tympanic membrane filled with
cheesy white squamous debris
– Surgery is required to remove this destructive
process
Conductive Hearing Loss
• Otosclerosis
– Fixation of the stapes
– inherited as an autosomal dominant trait
– hearing aid or a simple outpatient surgical
procedure (stapedectomy)
Sensorineural Hearing Loss
• Damage to the hair cells of the organ of Corti
may be caused by:
– intense noise
– viral infections
– ototoxic drugs
– fractures of the temporal bone
– meningitis
– cochlear otosclerosis
– Ménière's disease,
– aging
• If age-related abnormality in VISUAL ACUITY is
PRESBYOPIA, what is age-associated hearing
loss?
Sensorineural Hearing Loss
• Presbycusis –
– Age-associated hearing loss
– most common cause of sensorineural hearing loss
in adults
– Starts as loss of high frequency sounds
– Associated with loss in clarity
– Hearing aids
– Cochlear implants
Sensorineural Hearing Loss
• Ménière's disease
– characterized by episodic vertigo, fluctuating
sensorineural hearing loss, tinnitus, and aural
fullness
– distention of the endolymphatic system
(endolymphatic hydrops) leading to degeneration
of vestibular and cochlear hair cells
– low-salt diet, diuretics, GC