SENILE CATARACT- Pathophysiology, Symptoms, Complications
PATHOPHYSIOLOGY OF SENILE CATARACT
- Pathophysiology of loss of transparency of lens is different for nuclear & cortical senile cataract:
A) Cortical senile cataract:
The main biochemical features are:
- Decreased levels of total protein, amino acids & potassium.
- Increased concentration of sodium & marked hydration of lens.
- Coagulation & denaturation of lens proteins
B) Nuclear senile cataract:
- Usual degenerative changes are intensification of the age related nuclear sclerosis.
- Associated with dehydration & compaction of the nucleus resulting in a hard cataract.
|Visual field loss||All types of cataract|
|Frequent change of glasses||Cortical or nuclear cataract|
|Monocular diplopia or polyopia||Cortical cataract (Incipient stage) (spoke or cuneiform)|
|Colour shift (becomes more obvious after surgery)||Cortical cataract|
|Glare||Cortical & posterior subcapsular cataract|
|Loss of ability to see objects in bright sunlight, blinded by light of oncoming headlamps when driving at night.||Posterior subcapsular cataract
|‘Second sight’ or myopic shift
(change in refractive index of the nucleus causes index myopia improving near vision)
|Index myopia||Nuclear cataract|
|Index Hypermetropia||Cortical cataract|
COMPLICATIONS OF SENILE CATARACT
1. Lens induced Glaucoma: Cataract can give rise to secondary glaucoma in following ways:
i) Phacomorphic glaucoma:
- Lens may swell up by absorbing fluid resulting in shallow anterior chamber (intumescent cataract).
- Most common type of lens induced glaucoma.
- Beside intumescent stage of senile cataract, phacomorphic glaucoma is also seen in anterior subluxation/dislocation of lens & spherophakia (congenital small spherical lens).
ii) Phacolytic glaucoma:
- In hypermature stage the lens proteins leak out into the anterior chamber & engulfed by macrophages.
- A type of secondary open angle glaucoma.
iii) Phacotopic glaucoma:
- Hypermature lens subluxation/ dislocation may cause glaucoma by blocking the pupil or angle of anterior chamber.
2. Lens induced Uveitis
3. Subluxation or Dislocation of Lens
- In stage of of hypermaturity the zonules of the lens may weaken & break.
- This leads to subluxation of the lens or dislocation.
- Intumescent cataract is the most common type of lens induced glaucoma.
- Visual deterioration due to senile cataract is painless and gradually progressive in nature.
- Second sight phenomenon is seen in Nuclear cataract.
- Polyopia is a symptom of Cortical cataract.
- Most visually handicapping cataract is Posterior subcapsular cataract.
- Highest visual morbidity is seen in Posterior subcapsular cataract.
- Steroid induced cataract is Posterior subcapsular cataract.
- Nuclear cataract is most commonly associated with ageing.
- In senile nuclear cataract Index myopia is seen.
- Polychromatic Lustre is seen in Posterior cortical cataract.