Blindness
Cataract
Most
common cause of blindness in the
Clouding
of the lens or its capsule resulting in it becoming opaque or milky white.
Caused
by breakdown of the normal lens protein and the influx of water into the lens.
Associated
with ageing, injury, exposure to ultraviolet B, steroid use, and as a
complication of other diseases.
Glaucoma
Second
most common cause of blindness especially in the elderly.
Raised
IOP (Intraocular pressure).
Caused
by a build up of aqueous humor.
Failure
of aqueous humor to return to the bloodstream via the
Results
in pressure on the retina.
Damage leads to sight
impairment, VFDs and ultimately blindness by
degeneration of the optic disc.
Trachoma
Chronic
contagious conjunctivitis.
Greatest
cause of blindness in the world.
Aetiology is
Chlamydia trachomatis.
Results
in corneal opacity.
Detachment of the
retina
Caused by trauma or
other intraoccular disorder
Detachment occurs
between the inner layer of nervous tissue and the outer pigmented layer.
Accumulation of fluid
occurs forcing the retina out towards the vitrous
body.
This distorts vision
and causes blindness in the effected area
Treatment consists of
re-attachment by photocoagulation using laser, cryosurgery or scleral resection.
Senile macular
degeneration, (SMD)
New blood vessels
grow over the macular lutea.
Severity varies from
minor disturbances of vision to blindness.
Accounts for nearly
all new cases of blindness in the over 65s.
Aetiology is idopathic.
Laser treatment can
prevent blood vessel proliferation, this can sometimes restore lost site.
Cover one eye and
stare at any straight line, if the line appears bent or twisted or if a black
spot appears seek opthlamic advice.
Others
River blindness
Shortage of Vitamin A
Diabetic retinopathy
Deafness
Basically two types, Sensorineural and conduction
Sensorineural
Caused
by impairment of the Cochlea or cochlear branch of the VIII nerve.
Cortical causes
Conduction
Impairment
of the outer or middle ear sound conducting systems.
Specific causes
Genetic factors
Ostosclerosis, (new bone around the oval window).
Repeated exposure to noise, (destroys hair cells in the organ of Corti).
Streptomycin
Impacted cerumen
Injury to tympanic
membrane
Aging affects
Results in thickening
of the tympanic membrane
Stiffening of the
joints of the ossicles
Decreased numbers of
hair cells due to reduced mitotic activate
Otitis media
Very common in
children
Repeated infection
can have long term complications, such as glue ear, (adhesive otitis media), results from thickening of the mucous
membrane with fibrous tissue, can result in fixation of the ossicles.