Cataract Flashcards
What is a cataract?
Opacification of the natural crystalline lens
What are the 3 types of cataracts?
- nuclear sclerosis with lens becoming yellow/brown
- cortical
- posterior subcapsular
What happens to vision if cataracts seems developed?
Gradual deterioration as vision
What are cataracts the commonest cause of worldwide?
blindness
What are 6 things cataracts can be secondary to?
- age >65y (commonest)
- ocular disease e.g. post-inflammatory uveitis (posterior subcapsular cataract)
- systemic disease e.g. DM
- traumatic - lens capsule disruption
- drug induced: systemic corticosteroids (posterior subcapsular cataract)
- congenital
Do the majority of people with cataracts have other eye problems?
No - 70% have no other eye problems
What proportion of the 30% of cataract sufferers have glaucoma, AMD and diabetic retinopathy?
- Glaucoma: 11%
- AMD: 17%
- Diabetic retinopathy: 3%
What proportion of patients having cataract surgery have other medical conditions, and what could these include?
57% e.g. hypertension, arthritis, diabetes
What has happened to the trend in cataract surgeries performed?
rates have increased from 1997
Is there a primary or medical treatment for cataracts?
no (although many advances made in identification of risk factors)
What will happen to the trend in cataract prevalence and surgery?
will continue to rise due to increasing life expectancy
What are the symptoms of cataracts?
gradual blurred, misty vision; glare
What will the findings be on examination of a cataract?
grey/white pupil using pen torch, nuclear sclerotic cataract may appear yellow/brown, reduced red reflex using direct ophthalmoscope
What is the commonest type of cataract? (looks like standard mist at the front)?
nuclear sclerosis
What do each of the 3 types of cataracts look like? (look at pictures)
- nuclear sclerosis - standard mist at the front
- cortical - spiky in the middle (wedge-like opacities, in lens cortex)
- subcapsular - little splodge of mist, is at the back of lens capsule
What can cause posterior sub-capsular cataracts? 2 things
corticosteroids, uveitis
What are 3 indications for treatment of cataracts?
- when level of vision restricts normal activity
- patient factors - young divers
- ocular factors - diabetic cataracts have to be removed to allow fundal examination and treatment. certain types can induce glaucoma or uveitis and have to be removed
What are 2 ways of treating cataracts?
- refracting: cataract alters lens refractive index so usually treatable with myopic spectacle lenses
- surgery: removal of cataract by phacoemulsification and implantation of an artificial intraocular lens
What is the most commonly performed intraocular operation?
cataract surgery (most commonly performed operation under NHS)
what is usually the result of cataract surgery?
excellent return of vision if no other ocular pathology present. Overall 92% see 6/12 or better
What does cataract surgery involve?
under anaesthetic, use phaco tip. removing cloudy cataractous lens except for a thin, transparent posterior layer (posterior capsule). once cataract removed, eye is highly hypermetropic (long sighted). artificial lens implanted onto eye (intraocular lens IOL) and sits on posterior capsule behind the iris
What are 4 measurements that are used to calculate the intraocular lens power needed after cataract surgery?
- corneal curvature
- axial length of the eye
- depth of the anterior chamber
- A-constant of the lens
Why do you need to take specific eye measures before cataract surgery?
post-op refraction is tailored to individual patients
What are 2 types of anaesthesia used for cataract surgery and which is more commonly used?
general and local - local more common
What are 3 ways of administering local anaesthesia that can be given in cataract surgery?
- sub-tenon injection
- peri-bulbar injection
- topical (drops only)
What is the cataract surgery called?
phacoemulsification and posterior chamber intraocular lens (IOL) implant
What proportion of cataract surgery is under anaesthetic as day case surgery?
over 90%
How big is the incision that is made in cataract surgery?
4mm
What happens after the first incision is made in cataract surgery?
Removal of anterior lens capsule; high speed vibrating ultrasonic tip cuts nucleus into tiny particles and aspirates them. irrigation and aspiration of remaining cortex with posterior capsule retained. Insertion of IOL into capsular bag
How can the posterior chamber IOL be described?
foldable, e.g. silicone/acrylic
Why are no sutures done in cataract surgery?
to prevent astigmatism
What is healing like following cataract surgery?
fast healing, visual rehabilitation
What are 2 ways that the IOL can be implanted?
folded or injected
What does the IOL look like?
contact lens with two semicircle loops above and below the circle
What are 2 possible peri-operative complication of cataract surgery?
- Rupture of the posterior capsule leading to vitreous loss - 3%
- or rupture of posterior capsule causing dropping of nucleus into the vitreous
What are 7 possible post-operative complications of cataract surgery?
- endophthalmitis - ophthalmic emergency, delay in treatment may lead to blindness
- haemorrhage
- uveitis
- glaucoma
- macular oedema
- retinal detachment
- opacification of posterior lens capsule
How frequently after cataract surgery does endophthalmitis occur?
0.1%
Over what time period might some patients develop opacification of the clear posterior capsule after cataract surgery?
months or years following surgery
Why might treatment be needed due to opacification of the posterior capsule months or years after cataract surgery?
if vision significantly reduced
What is the treatment for the opacification of the posterior capsule following cataract surgery?
, laser treatment Nd:YAG laser - outpatient; required to make hole in posterior capsule to clear the visual axis (laser rate about 5% of all procedures)
What type of cataract can occur secondary to post-inflammatory uveitis?
Posterior subcapsular
