Cataract: A Brief OverviewApril 24, 2013 | 4:03 pm | Ophthalmology | No Comment
The word ‘cataract’ dates from the middle Ages and has been derived from the Greek word ‘katarraktes’ which means ‘waterfall’. This term has been coined assuming that an ‘abnormal humor’ developed and flowed in front of the lens to decrease the vision. But after the understanding of lens anatomy, in modern days, Cataract is defined as the presence of any opacity in lens or its capsule.
SO WHAT CAUSED THE PRESENCE OF SUCH OPACITY IN LENS?
The opacities may occur, either due to the formation of opaque lens fibres (congenital and developmental cataracts) or due to the degenerative process leading to opacification of a normally formed transparent lens fibres (acquired cataract).
Among the congenital cataracts and those formed during the developmental process of a child, about one third cases are idiopathic, one third are hereditary and the rest one third are due to other causes like malnutrition, maternal infections like rubella, toxoplasmosis, cytomegalo-inclusion disease, drugs like thalidomide, corticosteroids, radiation, fetal or infantile factors like anoxia, birth trauma, metabolic disorders or associated with other congenital anomalies like Lowe’s syndrome.
‘Age-related cataract’ also called senile cataract is the commonest type of acquired cataract affecting equally the persons of either sex usually above the age of 50 years. Smoking has also been reported to have some effect on the age of onset of senile cataract.
Morphologically, cataract can be classified as:
A. Capsular cataract
- Anterior capsular cataract
- Posterior capsular cataract
B. Subcapsular cataract
- Anterior subcapsular cataract
- Posterior subcapsular cataract
C. Cortical cataract
D. Supranuclear cataract
E. Nuclear cataract
F. Polar cataract
- Anterior polar cataract
- Posterior polar cataract
- Asymptomatic and maybe discovered in routine ocular examination.
- Glare or intolerance of bright light such as sunlight or headlight of an incoming vehicle is one of the earliest visual disturbances.
- Uniocular Polyopia(i.e. seeing single object as multiple)
- Colored halos
- Black spots in front of eyes
- Image blur, distortion of images and misty vision
- Painless loss of vision with gradual onset
B. Signs: may vary with the type of cataract. The following examination should be carried out to look for different signs of cataract.
- Visual acuity testing – 6/9 to just PL+
- Oblique illumination examination to look for the color of lens in papillary area
- Test for iris shadow
- Distant direct ophthalmoscopic examination
- Slit-lamp examination in a fully dilated pupil to see for the complete morphology of opacity (site, size, shape, color pattern and hardness of the nucleus).
The hardness of the nucleus, depending upon the color on slit-lamp examination, can be graded as shown in the table below:
|Grade of hardness||Description of hardness||Color of nucleus|
|Grade I||Soft||White or Greenish yellow|
|Grade V||Ultrahard (rock-hard)||Blackish|
Treatment of cataract essentially requires its surgical removal. However, non surgical measures may be of help, in peculiar circumstances, till surgery is taken up.
A. Non – surgical measures
- Treatment of cause of cataract
- Adequate control of Diabetes Mellitus, when discovered.
- Removal of cataractogenic drugs such as corticosteroids, phenothiazenes and strong miotics, may delay or prevent cataractogenesis.
- Removal of irradiation (infrared or X – rays)
- Early and adequate treatment of ocular diseases.
- Delaying progression of cataract
- Measures to improve vision in the presence of incipient and immature cataract.
B. Surgical measures
- Intracapsular Cataract Extraction(ICCE)
- Extracapsular Cataract Extraction(ECCE)
Nowadays, the use of ICCE is obsolete and the only indication of using ICCE is markedly subluxated or dislocated lens.
Surgical techniques of extracapsular cataract extraction for adulthood cataracts
- Conventional extracapsular cataract extraction
- Manual small incision cataract surgery
Phacoemulsification is presently the most popular method of extracapsular cataract extraction.
Surgical technniques of extracapsular cataract extraction for childhood cataract
- Irrigation and aspiration of lens matter
Tags: cataract, eye surgery
Last updated: May 5, 2013