Cataract is the pathological condition in which the normal transparency of the lens is disturbed due to the degenerative changes leading to opacification of the lens fibers. Development of the opacity of the lens is known as cataract.
What Are The Different Types Of Cataract?
- Congenital and Developmental Cataract.
- Senile Cataract-
- Anterior capsular.
- Posterior capsular.
- Anterior Sub capsular.
- Posterior Subcapsular.
Nuclear Cataract are classified as-
Embryonic Nuclear Cataract– This type of Cataract occurs due to some genetic abnormalities. This type of Cataract has a dominant genetic trait and thus causes the inhibition of lens development at a very early stage of fetal development and hence involves only nuclear part of the lens. This type of Cataract usually occurs bilaterally.
As Nucleus is the center most part of the lens, so it is characteristically present with small, round, central opacities which lie exactly at the center of the eyes.
Embryonic nuclear Cataract develops during the intrauterine life so these are usually not progressive in nature.
Total Nuclear Cataract– In this, there is involvement of embryonic, fetal, and sometimes infantile nucleus. These are characterized by chalky white central opacities seriously affecting vision. These are usually bilateral and non- progressing in nature.
Nuclear Senile Cataract– In this of Cataract, the Degenerative changes are just the intensification of age-related sclerosis of the nucleus part of the lens which is commonly associated with dehydration and compaction of nuclear part of the lens which results in hard Cataract. There is a significant rise in the water-soluble protein content. However, the total protein content and the ionic balance are maintained.
- It is the most common type of age-related cataract developing due to hardening and sclerosing of the central part of the lens over the period of time.
- Sometimes they are associated with the deposition of certain pigment in the lens like melanin derived from the metabolism of amino acid in the lens.
Cortical Cataract refers to as the development of the white or cloudy opacities in the cortex of the lens. Due to the involvement of the cortex, these cataracts are peripheral.
The pathological changes in the associated with cortical cataract are decreased in the content of total protein, amino acid, and potassium. There is also increase in the concentration of sodium and there is marked hydration of lens which causes the coagulation of the lens proteins.
Maturation of Senile cortical Cataract-
A Sign Of Lamellar Separation– This stage is reversible. The earliest sign of senile changes is the demarcation of the cortical fibers due to their separation by the increased hydration by the fluid.
Stage of Incipient Cataract- It is of two types:
- Cuneiform– It is characterized by wedge-shaped opacities with clear areas in between. These extend from the periphery towards center hence in early stages can only be seen after dilatation of pupil. On oblique illumination, these present as typical radial spoke like the pattern of greyish white opacities. On direct ophthalmoscopy these appear as Dark lines in red fundal glow.
- Cupuliform– Here saucer-shaped opacities develop just below the capsule in the posterior cortex.
Immature Senile Cataract– Here the opacification progresses further to involve a large area of the lens. In advance stage, there is no differentiation of cuneiform and Cupuliform types. Some clear cortex is still present so Iris shadow is visible and the lens appears greyish white.
Mature Senile Cataract– This stage is also known as a ripe cataract. Here the opacification completes and there is no clear cortex remains. The lens appears pearly white in color.
Hypermature Senile Cataract– When the mature cataract is left in situ, and then the stage of hypermaturity sets in. In some patients, the cataract liquefied and the lens is converted into a milky bag.
Sub-Capsular Cataract– This type of cataract develops just beneath the capsule, so is the name. The capsule is a bag like structure which enclosed the lens. It holds the lens in its place. Subcapsular cataract interferes with the vision and produces a Halo effect and glare. This type of cataract progresses rapidly and the symptoms become noticeable within few months.
Cataract is the development opacities in the lens. They are classified on the basis of etiology involved or on the basis of their morphology. Nuclear cataract is hard and causes an early defect in central vision. A cortical cataract develops from periphery and progress to central part so there is the loss of peripheral field in the acute stage. Subcapsular cataract generally develops in the posterior part of the lens below the capsule.
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