1. Astigmatism occurs when the cornea or lens is oblong rather than spherical, causing light rays to focus at different points. It is corrected using a cylindrical lens to focus all rays in one line. 2. Cataracts cause lens opacity from protein denaturation, impairing vision as light transmission is obscured. Correction involves removing the lens and replacing it with a convex lens or prosthetic lens. 3. The fluid system in eyes includes aqueous humor and vitreous humor, which are formed and drained through various processes to maintain sufficient pressure in the eyeball. Blockages can cause increased intraocular pressure leading to glaucoma.

1. Poonch Medical College Rawalakot

2. Astigmatism
• Light rays find asynchronous planes of refracting surface so light rays
come to focus at different points forming Different Focal Points
• Shape of cornea or lens altered to oblong instead of usual spherical
• CORRECTION
Requires cylindrical lens which can focus all rays in one line. Two
lenses one spherical and other cylindrical are found that correct error
in two planes and placed perpendicular to each other

4. Cataracts
• Lens opacity due to protein denaturation
• Opacity causes the loss of passage of light from previously
transparent lens
• There is reduced elasticity of the lens as well
• When there is obscured light transmission vision is impaired
Correction
Lens removal with convex lensplaced in front to replace natural lens
Prosthetic lens replacing lens in the eye

5. Fluid System of Eyes
• Fluid in eyes maintains sufficient
pressure in the eyeball to keep it
distended
• Two components
aqueous humor
 vitreous humor

6. Aqueous humor
• Aqueous humor is formed in the
eye at an average rate of 2 to 3
μL/min
• Formed by ciliary processes(6
square centimeters in each eye
)
• active transport of sodium ions,
which pull chloride and
bicarbonate ions along, osmosis of
water from the blood capillaries
also there is active tr./ facilitated
diff. ofamino acids, ascorbic acid,
and glucose.

7. Flow of fluid
Ciliary process
through the
pupil into the
anterior
chamber of the
eye
angle between
the cornea and
the iris
meshwork of
trabeculae(rich
in phagocytic
cells)
canal of
Schlemm(rich in
R.E cells)
extraocular
veins

8. Draining channel for aqueous humor
• Trabeculea at iridocorneal
junction line thin walled canal of
schlemm
• Canal of schlemm can drain big
size molecules into side wise
places aqueous veins
• Any blockade at the draining
level can cause resorption failure
and may lead to raised
intraocular pressure
• Trabeculectomy

9. Glaucoma
• Normal intraocular pressure is about 15 mm Hg, with a range from 12
to 20 mm Hg.
• May raise to 25 to 35mmHg tO as high as 75mmHg which can cause
blindness
• Causes; acute eye inflammation, white blood cells and tissue debris
can block these trabecular spaces
• Alfa agonists and trabeculectomy