Cataract Flashcards
What is a cataract?
Any opacity (loss of transparency) of the lens The cloudiness makes it more difficult for light to react retina, thus causing reduced/ blurred vision
A cataract may result from disruption to the…
Lens fibre configuration, capsule or epithelium
What is the most common cause?
Increasing age
Are cataracts more common in men or women?
Women
Other than old age, what else can cause cataracts?
Trauma - direct injury to lens, electric shock/ lightening
Smoking and alcohol
Systemic disease: DM, myotonic dystrophy, neurofibromatosis type 2
Drugs: steroids, amiodarone, allopurinol
Hypocalcaemia
Sunlight exposure
Radiotherapy
HIV positive
How do patients typically present?
Gradual onset of: Reduced vision Faded colour vision Glare - light appears brighter than usual Halos around light Difficulty driving at night Loss of stereopsis - affect distance judgement (perception of depth) Monocular diplopia
Unilateral cataracts are often unnoticed
How can cataracts be classified?
Nuclear
Subcapsular
Cortical
Where are subcapsular cataracts located and what do they look like?
Directly under lens capsule
Granular or plaque like appearance
What symptoms are associated with subcapsular cataracts?
Near vision affected more than distance as opacity at nodal point of eye
What are subcapsular opacities generally caused by?
Steroid use
Where are nuclear cataracts found?
Involve the lens nucleus
Yellowish brown due to deposition of urochrome pigment
What symptoms are associated with nuclear cataracts?
Myopic due to increased refractive index of lens
Dulls colour - more yellow/ brown
Common in old age
Where are cortical cataracts found?
Cortex of lens
Radial spokes in periphery
What symptoms are associated with cortical cataracts?
Milder effects on vision
Astigmatic changes
Trouble more in dark when pupil wider and exposes more of cataract
What signs are associated with cataracts?
Defect in red reflex (cataract prevents light getting through to retina)
What is the red reflex?
The red/ orange reflection seen through an ophthalmoscope when light shone on retina
What investigations should be done?
Ophthalmoscopy done after pupil dilation - normal fundus and optic nerve
Slit lamp examination- visible cataract
Are cataracts the leading cause of curable blindness worldwide?
Yes
Cataracts are found in what percentage of over 65s?
75%
How do cataracts present in children?
Squint
White pupil
Nystagmus
What is astigmatism?
When eye shaped more like rugby ball than football - light focused at more than one place in the eye.
Causing: blurred vision, headaches, eye strain
Alongside short or long sighted
What non surgical management options can be taken?
Stronger glasses/ contacts
Encourage use of brighter lighting
Sunglasses
Ways to optimise vision - do not actually slow down progression of cataracts
What is the only effective treatment for cataracts?
Surgery
What is the name of the most common surgical technique for cataract surgery?
Phacoemulsification
Explain the process of phacoemulsification
Usually under local anaesthetic, patent prone
Entry to eye via limbus (peripheral cornea)
Lens removed by phacoemulsion - US breaks it up and it is aspirated into cannula
Incision slightly enlarged and artificial lens implanted
New lens calculated to correct the patients’ refractive error
Patient can usually go home same day with a dressing. Full activities can be resumed next day.
NICE suggests that a referral for surgery should depend on…
If visual impairment present Impact on QOL Patient choice Whether one or both affected Risks of surgery
What are some complications of surgery?
Posterior capsule thickening of the lens capsule - can opacify
Endophthalmitis- inflammation of aqueous and/or vitreous humour
Retinal detachment
Posterior capsule rupture
What are some preventative measures?
Sunglasses
Reduce oxidative stress - vit c
Stop smoking
If there is a congenital cataract, the patient needs to be referred to ophthalmologist urgently for surgical consideration. How soon does integration need to be done?
1st 6 weeks of life (latent period of visual development)
To prevent significant deprivation amblyopia
What percentage of congenital cataracts have a genetic cause?
50%
What screening should be done if patient has congenital cataracts?
TORCH screen = group of blood tests to check for several infections in newborn Toxoplasmosis Rubella Cytomegalovirus Herpes simplex HIV
If a cataract develops in first 6 months of life, what is it called?
Infantile cataract
What is amblyopia?
When the visual system is prevented from developing properly - particularly if brain doesn’t get chance to see clear images in first few months of life
(If child has unilateral cataract, brain may favour images from the good eye)
Other than infection, what else can cause cataracts?
Metabolic diseases
Genetic e.g Down syndrome
Undetermined cause
