Cataracts Flashcards
What is a cataract?
painless opacification of natural crystalline lens leading to gradual deterioration in vision
Commonest avoidable cause of blindness worldwide
What are the three forms of cataracts?
1) nuclear sclerosis, where the lens becomes yellow/brown
2) cortical
3) posterior subscapular - related to previous uveitis or corticosteroid use
What are the causes of cataracts?
most are age related
Secondary to occular (post-uveitis) or systemic disease (DM), traumatic due to lens capsule disruption, drug induced by corticosteroids or congenital
What symptoms does the patient tend to complain of?
gradual blurring/misting of vision or if the cataract is at the back of the lens they will complain of glare
What other conditions are commonly associated with cataracts?
Just over half of patients having cataract surgery will have another medical condition
- 30% hypertension
- 18% arthritis
- 11% diabetes
What will be noted on examination of the patient?
greying of the pupil under pen torch (yellow brown in nuclear sclerosis)
reduced red reflex using a direct opthalmoscope
When is cataract surgery offered?
when the level of vision restricts normal activity
- pt factors also important = diabetic cataracts need to be removed to enable fundal examination and treatment
What can certain cataracts lead to?
glaucoma or uveitis
What is the initial treatment for cataracts?
myopic spectacle lenses, as cataracts will alter the lens’ refractive index but if this doesnt work surgery will be required
What happens in cataract surgery?
removal of the cataract by phakoemulsification and implantation of an artificial intraocular lens
-the artificial lens is important because once the cataract is removed it caused hypermetropia
What is the overall prognosis following surgery ?
overall - 92% see 6/12 or better
ocular co-morbidity- 78% see 6/12 or better
no ocular comorbidities- 96% see 6/12 or better
(6/12 = driving level standard)
How is the pt anaesatised or this day case surgery?
local anaesthetic - either sub-tenon or peri-bulbar injection or topical drops
How is the surgery performed?
1) small 4mm incision is made and anterior lens capsule is removed. High speed vibrating ultrasonic tip is inserted cutting the nucleus into tiny pieces that are then aspirated
2) posterior capsule is retained and then there is insertion of a new artificial intraocular lens
3) no sutures are inserted, reducing astigmatism and enabling fast healing
Where does the IOL sit?
implanted into the eye and sits on the posterior capsule behind the iris
Why do the IOL vary for each person?
The power of the IOL is individually calculated for each pt dependent upon their corneal curvature, axial eye length and anterior chamber depth
- post operative refraction is also individually tailored to the pt
