Lens, Shalakya Tantra
LENS
Lens is a transparent, biconvex structure with rounded border (equator), the main function is to converge the light rays to form image on retina properly, anterior surface is less convex than posterior surface, it is kept in its position by suspensory ligaments or zonule which is extending form ciliary body, its position is posterior to iris and anterior to vitreous, it is made up of Lens fibres and enclosed in an elastic capsule.
Lens axis deviates from visual axis by about 4°, underneath the lens capsule there is a single layer of cubical epithelium from which the lens fibres are developed and arranged concentrically around the axis like the scales of an onion. Central part of lens which is hard is known as nucleus and peripheral part which is soft is known as cortex.
Axial diameter 3.5 to 4mm equatorial diameter 8 to 10 mm weight of lens approx 0.2 grams Volume of Lens approx 0.163 ml
Parts : (1) Capsule (a) zonular lameliae or pericapsuiar layer to which suspensory ligament is attached (b) Capsule proper.
(2) Subcapsular epithelium it is a single layer of epithelium from which the Lens fibres are developed and it is situated underneath the anterior capsule only.
(3) Lens (fibres) substance :Lens fibres are developed from sub capsular epithelium and arranged concentrically arround the axis like the scales of an onion, centrally placed cells known as nucleus and peripherally placed cells known as cortex. Lens fibers while moving from equator to Anterior and posterior poles coverge at a point and form sutures, cortical sutures are multi radiated and nucleus sutures are tri radiated, Anteriorly Y shaped and posterioriy inverted Y shaped. Lens fibres doesn’t exfoliate collected even from foetal life and are tightly burried at the nucleus.
Embryonic fibres Foetal fibres Infantile fibres Adult fibres } In the interior nucleus
Arranged from interior to Adult fibres Exterior gradully.
So only by age the lens nucleus becomes hard flat (due to tightly crushed lens fibres at nucleus) hypermetropic with increased density, so only ‘iens appears as grey, it is a physiological process, ultimately causes iental sclerosis.
Chemical Composition
63% to 69% water 35 to 36% proteins crystailines aibuminoid
1% lipoids, in organic ions. carbo hydrates, ascorbic acid, glutathione and amino acids.
Lens is a transparent, biconvex structure with rounded border (equator), the main function is to converge the light rays to form image on retina properly, anterior surface is less convex than posterior surface, it is kept in its position by suspensory ligaments or zonule which is extending form ciliary body, its position is posterior to iris and anterior to vitreous, it is made up of Lens fibres and enclosed in an elastic capsule.
Lens axis deviates from visual axis by about 4°, underneath the lens capsule there is a single layer of cubical epithelium from which the lens fibres are developed and arranged concentrically around the axis like the scales of an onion. Central part of lens which is hard is known as nucleus and peripheral part which is soft is known as cortex.
Axial diameter 3.5 to 4mm equatorial diameter 8 to 10 mm weight of lens approx 0.2 grams Volume of Lens approx 0.163 ml
Parts : (1) Capsule (a) zonular lameliae or pericapsuiar layer to which suspensory ligament is attached (b) Capsule proper.
(2) Subcapsular epithelium it is a single layer of epithelium from which the Lens fibres are developed and it is situated underneath the anterior capsule only.
(3) Lens (fibres) substance :Lens fibres are developed from sub capsular epithelium and arranged concentrically arround the axis like the scales of an onion, centrally placed cells known as nucleus and peripherally placed cells known as cortex. Lens fibers while moving from equator to Anterior and posterior poles coverge at a point and form sutures, cortical sutures are multi radiated and nucleus sutures are tri radiated, Anteriorly Y shaped and posterioriy inverted Y shaped. Lens fibres doesn’t exfoliate collected even from foetal life and are tightly burried at the nucleus.
Embryonic fibres Foetal fibres Infantile fibres Adult fibres } In the interior nucleus
Arranged from interior to Adult fibres Exterior gradully.
So only by age the lens nucleus becomes hard flat (due to tightly crushed lens fibres at nucleus) hypermetropic with increased density, so only ‘iens appears as grey, it is a physiological process, ultimately causes iental sclerosis.
Chemical Composition
63% to 69% water 35 to 36% proteins crystailines aibuminoid
1% lipoids, in organic ions. carbo hydrates, ascorbic acid, glutathione and amino acids.
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