Page 78 - The Book Pi in eye

Rajesh Khanna, MD

Causes of dry eyes:

Let us consider an example of a wash basin, where we want an
optimum level of water to be always present so we can float a paper
boat. The tap produces water at a predetermined rate and a drain
stopper regulates the exit of water from the basin. Under these
conditions our paper boat can float around. The level of water will
decrease if the tap does not produce enough water. If the room is
dry, hot or windy the water will vaporize. Finally, if the drain stopper
leaks water, the boat will sink. Decreased tear production due to
ageing, infection or inflammation is akin to an improperly
functioning tap. Increased evaporation may account for decreased
tear lake leading to irritated eyes. Rarely the outflow channels, the
punctum, may be too big.

Decreased Production:
1. Atrophy of tear producing cells.
2. Inflammation
3. Suppression by drugs
4. Congenital absence
5. Tumors
6. Surgical excision of tear producing glands

Increased Evaporation
1. Air Conditioning
2. Heat in cold climate
3. Outdoor exposure to sun
4. Infrequent blinking

Increased drainage
If the tear punctum is too big or duplicated.

Poor Blinking
1. Habitual
2. Lid tumors
3. Nerve damage

Incorrect Composition

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