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Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. [1] Most tonometers are calibrated to measure pressure in millimeters of mercury .
Ocular hypertension is the presence of elevated fluid pressure inside the eye (intraocular pressure), usually with no optic nerve damage or visual field loss. [1] [2]For most individuals, the normal range of intraocular pressure is between 10 mmHg and 21 mmHg. [3]
When the sensor is subjected to a change in pressure, the electrical resistance is altered and the tonometer's computer calculates a change in pressure according to the change in resistance. A complete measurement cycle requires about eight seconds of contact time. The device also measures the variation in pressure that occurs with the cardiac ...
This can mean that systolic pressure is abnormally high, but diastolic pressure may be normal or low, a condition termed isolated systolic hypertension. [80] The high pulse pressure in elderly people with hypertension or isolated systolic hypertension is explained by increased arterial stiffness , which typically accompanies aging and may be ...
Blood pressure is recorded as two readings: a higher systolic pressure, which occurs during the maximal contraction of the heart, and the lower diastolic or resting pressure. [11] In adults, a normal blood pressure is 120/80, with 120 being the systolic and 80 being the diastolic reading. [ 12 ]
The researchers found that when people had their arms hanging by their sides during the reading, their systolic pressure was 6.5 points higher than when their arms were resting on a desk, while ...
The Schiotz tonometer consists of a curved footplate which is placed on the cornea of a supine patient. A weighted plunger attached to the footplate sinks into the cornea. A scale then gives a reading depending on how much the plunger sinks into the cornea, and a conversion table converts the scale reading into IOP measured in mmHg.
Pulse pressure is considered low if it is less than 25% of the systolic. (For example, if the systolic pressure is 120 mmHg, then the pulse pressure would be considered low if it is less than 30 mmHg, since 30 is 25% of 120.) [91] A very low pulse pressure can be a symptom of disorders such as congestive heart failure. [52]