Adult Cataract Flashcards
What is a cataract?
A condition characterized by the discoloration or the clouding of the ocular lens which causes the decline in vision and eventually lead to blindness if left untreated
Epidemiology of adult cataract?
- leading cause of reversible blindness
- World wide, an estimated 95 million people are affected by cataract and it is the leading cause of blindness in middle and low income countries
- Cataract In Africa caused almost 6 million individuals to be blind
Patho physiologies of cataract?
- Age
- Ageing causes lens protein changes, this causes fluctuations in the refractive index of the lens, scatter light rays and reduce transparency. - Trauma
- Trauma directly compromise the lens capsule that leads to cortical opacification at the site of injury - Diabetes
In diabetic cataract, when blood sugar levels are elevated beyond 200 mg per ml, excess glucose is converted to sorbitol
- This accumulates in the lens fibres and causes osmotic imbalance. - Stress
- Injury to the lens due to oxidative stress
- Lens proteins are damaged which leads to aggregation and loss of lens transparency
Classifications of the types of cataracts?
- By morphology
- nuclear, cortical, subcapsular - By eotiology
- traumatic, diabetic, drug induced - By age group
- Congenital, juvenile, senile - By stages of maturity
- Immature, mature, hypermature
Subscapular cataract?
- It manifests directly under the lens capsule
- is classified into anterior and posterior
- In anterior the cataract lies directly under the lens capsule
- In posterior, the cataract forms on the backside of the lens
- It’s caused by ageing, diabetes, steroid use and trauma.
Nuclear cataract?
- It affects the center of the lens
- the central area of the lens hardens and turns brown or yellow
- It eventually spreads to other areas of the lens
- It’s often caused by aging.
Second sight phenomenon?
- Nuclear cataract is often associated with myopia due to an increase in the refractive index of the nucleus
- resulting in some elderly patients being able to read without spectacles again
- ‘second sight of the aged’
Cortical cataract?
- The cataracts form from the edges and spread towards the center, forming a wedge shaped opacity
- It’s commonly caused by diabetes and aging.
Congenital cataract?
- They are present at birth or form during the babies’ first year
- They may be caused by TORCH infections, disorders of metabolism or hereditary syndromes
Secondary cataract?
Develops as a result of other primary ocular diseases
e.g. chronic anterior uveitis and acute congestive angle glaucoma.
Traumatic cataract?
- Most common cause of unilateral cataract in the youth
- Blunt trauma, penetrating trauma, radiation, electric shock can all result in cataract surgery
Cataract secondary to systemic diseases?
Systemic diseases like DM or hypertension can also cause cataract
Immature cataract?
- Early stages of cataract progression and the lens is partially opaque
- Red reflex is still present allowing the retinal visualization
Mature cataract?
- Advanced stage in cataract progression
- The lens are completely opaque with absent red reflex
- White-yellow lens discoloration with only light perception
Hypermature cataract?
- End stage of cataract progression
- a shrunken and wrinkled anterior capsule
Morgagnian cataract?
Hypermature cataract in which liquefaction of the cortex has allowed the nucleus to sink inferiorly
Non modifiable risk factors in developing cataract?
- Old age
- Family history
- Female gender
Modifable risk factors for developing cataract?
- Diabetes mellitus
- Hypertension
- Excessive exposure to sunlight
- Smoking
- Obesity
- Excessive alcohol drinking
- Previous eye injury or inflammation
- Previous eye surgery
- Prolonged use of corticosteroid medication
Clinical features of cataracts?
- Reduced visual acuity
- Clouded, blurred or dim vision
- Seeing halos around lights
- Change perception of colours
- Double vision in a single eye
- Difficulties with vision at night
- Decreased sensitivity to bright light and glare to on coming head lights
Ddx for cataracts?
- Glaucoma
- Refractive errors
e.g. myopia, hyperopia, astigmatism - Macular degeneration
- Diabetic retinopathy
- Corneal dystrophy and degeneration
- Optic atrophy
- Retinitis pigmentosa
Investigations of adult cataract?
- Ophthalmoscopy
- Slit lamp examination
- Ultrasound scan(B scan)
- Visual acuity testing
Treatment of of adult cataract?
- The definitive management of cataract is surgery
- No pharmacological agent can treat cataract
Complications of adult cataract?
- Blindness
- Glaucoma
- Deprivation amblyopia
