thee lens Flashcards
what is cataract ?
clearing of the normally clear lens
what is the cause of blurry vision in cataract ?
cloudiness of the lens doesn’t allow for the focusing of light on the retina - leading to blurry vision
what are the different types of cataract ?
congenital
acquired
secondary
traumatic
what are the causes of acquired cataract ?
either due to aging
or due to systemic or local causes
what are the different types of cataract maturity ?
immature - partially opaque
mature - totally opaque
hyper mature -shrunken and wrinkled anterior capsule due to leakage of water out of the lens
what are the types of age related cataract ?
subcapsular cataract
nuclear cataract
cortical cataract
what is the pathology in sub capsular cataract ?
lies directly underneath the capsule whether anterior or posterior
due to fibrous metaplasia of the lens epithelium
posterior sub capsular has a profound effect on vision
what is the pathology in nuclear cataract ?
nuclear sclerotic cataract is considered an exaggerated aging process
deposition of urochrome pigments giving it a yellow hue
what is the second sight of age phenomenon ?
nuclear cataract is associated with myopia due to the increased refractive index of the nucleus resulting in some elderly patients being able to read again without spectacles
what is the pathology associated with cortical cataract ?
opacities start as clefts between fibres of the lens then opacification occurs due to cortical hyddration
what is the typical image of opacities in cortical cataract ?
typical wedge shaped
or
radial spoke like opacities
what cause of congenital cataract is associated with cortical cataract ?
Lowe’s syndrome
what cause of congenital cataract is associated with radial spoke like arrangements of opacities in the posterior lens cortex ?
mannosidosis
what are the systemic diseases associated with cataract ?
Diabetes
Myotonic dystrophy: Beckers and Duchenne
Neurofibromatosisi type 2
Atopic dermatitis
what is the pathology in cataract associated with diabetes ?
glucose is metabolized into sorbitol
sorbitol accumulates inside the lens
becomes osmotic due to over hydration
fluctuations in sight in diabetes ?
hyperglycaemia - inc RI - myopia
hypoglycaemia - dec RI - hypermetropia
what does classical diabetic cataract look like ?
snowflake cortical appearance
but rare
what type of cataract forms in myotonic dystrophies
?
wedge shaped cortical opacities with a star configuration
what type of cataract is associated with atopic dermatitis ?
cataracts are Shield-like dense anterior subcapsular plaque that wrinkles the anterior capsule
what is the type of cataract associated with neurofibromatosis type 2 ?
posterior subcapsular
capsular
cortical
or mixed
what are the local diseases of the eye associated with cataract ?
chronic anterior uveitis
acute congestive glaucoma
high myopia
hereditary fundus dystrophy
or secondary to mediications
what is the most common cause of secondary cataract ?
chronic anterior uveitis
related to duration and intensity of inflammation
what does the cataract look like associated with acute congestive glaucoma ?
anterior grey white capsular opacities in the pupillary area
glaukomflecken
what is thee association between high myopia andd cataract ?
associated with posterior subcapsular lens opacitty
and early onset nuclear sclerosis
what are the hereditary fundus dystrophies ?
retinitis pigmentosa
leber congenital amaurosis
Stickler syndrome
what is the type of cataract associated with steroids whether topical or systemic ?
posterior sub capsular
what is the most common cause of unilateral cataract in young individuals ?
traumatic cataract
what other ocular injuries are associated with traumatic cataract ?
iridiodialysis
seperation of the iris from its insertion on the ciliary body
what are the symptoms of cataract ?
blurry vision - cloudy
photophobia glare - halos around light especially at night
changes of glasses prescription ( including sudden near sightedness )
need for brighter light to read
difficulty seeing at night
what are the indications of surgery in age related cataract ?
visual improvement - most important indication
cataract affecting health of the eye
what is the concept in cataract surgery ?
removal of the clouded lens
insertion of thee IOL
what is the difference between ICCE and ECCE surgery ?
ICCE - removal of thee whole lens including the capsule
ECCE - lens is reemoved capsule is left for thee IOL
when is ECC indicated ?
in patients with very hard cataract
what is phaeoemulsification ?
emulsification of the contents of the lens using ultrasonic vibrations
aspirating the emulsified cataract
new IOL implants
conventional surgery nowadays
what are the ophthalmic pre operative assessments ?
visual acuity
cover test - to seen if there is any amblyopia
pupillary reflex - as cataract doesn’t cause RAPD
Cornea examination
Anterior chamber depth
lens
Fundus exam
current refractive status
informed consent
biometry
what are thee operative complications associated with cataract surgery ?
post op endophthalmitis
rupture of the posterior capsule of the lens
loss of some lens fragments in the vitreous
dislocation of the IOL
suprachoroidal hge
what is ectopia lentis ?
displacement of the lens from its place
what are the types of ectopia lentis ?
hereditary
acquired
what are the 2 possible presentations of ectopic lentis ?
luxated - making the eye essentially aphakic
subluxated - partial displacement
what is the clinical presentation of the early stages of subluxation ?
phacodenesis - vibration of the lens with eye movement
what are the acquired causes of ectopia lentis ?
Hypermature cataract
Inflammatory - chronic uveitis
Trauma
Large eye - bupthalmous , high myopia
A - anterior uveal tumors
what are the hereditary causes of ectopica lentis ?
with no systemic association :
ectopia lentis et pupillae
familial ectopic lentis
with systemic associations :
Marfans syndrome
homocystinurea
Weill-Marchesani Syndrome
what is thee mode of inheritance of
ectopica lentis et pupillae
familial ectopica lentis
ectopica lentis et pupilla : AR
familial ectopica lentis : AD
what is the presentation of ectopica lentis et pupillae ?
congenital bilateral affection where thee pupil and the lens are displaced in the opposite direction
asymmetric and eccentric
oval pupils dilate poorly
what is the presentation of familial ectopica lentis ?
symmetrical
supertemporal dislocation of thee lens
what are the features of marfan’s syndrome ?
superotemporal subluxatiioin
high-arched plate
long fingers andd toes
what are the ocular features associated with marfan’s syndrome ?
superotemporal lens dislocation
glaucoma
retinal detachement
strabismus
what are the systemic features of weill-marchesani syndrome ?
short fingers
short stature
learning difficulties
what are the ocular manifestations of weill-marchesani syndrome ?
ectopica lentis subluxation is in the inferior direction
microspherophakia
what is a common ocular compliicattion associated with weill-marchhesani synddrome ?
acute angle closure glaucoma
what are the systemic features of homocystinuria ?
coarse blonde hair
blue irises
malar flush
what are the ocular manifestations associated with homocystinuria ?
zonules are lax
so lack of accomodation
ectopia lentis is infero nasal
what is the treatment for homocystinuria ?
oral pyridoxine
folic acid
vitamin b12
