What is the normal intraocular pressure in an adult?

Appeared in: AIIMS Rishikesh NO - 2019

Explanation

The accepted normal range for intraocular pressure (IOP) in adults is between 10 and 21 mm Hg.
This pressure is essential for maintaining the shape of the eyeball and ensuring the health of the optic nerve.
The option '10 to 20 mm of hg' most accurately represents this standard physiological range.
This balance is achieved through the continuous production and drainage of a fluid called aqueous humor.

Option A: While this range falls within the normal limits, it is less inclusive than the standard 10-21 mmHg range. It excludes the lower normal values between 10 and 11 mmHg.
Option C: This range represents ocular hypotony, which is an abnormally low intraocular pressure. It can lead to complications such as corneal edema, cataracts, and vision distortion.
Option D: This range indicates pathologically high intraocular pressure, a key sign of glaucoma. Pressures this high can cause rapid and irreversible damage to the optic nerve, leading to blindness.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Normal Intraocular Pressure (IOP) in Adults as background academic context rather than a clinical decision trigger.
Nurses play a crucial role in screening for glaucoma by identifying at-risk patients (e.g., those over 40, with a family history of glaucoma, diabetes, or cardiovascular disease).
Patient education is vital. Nurses must teach patients about the importance of regular eye exams for early detection and adherence to prescribed eye drop regimens to control IOP.
What if? A patient's screening IOP is 24 mmHg, but they report no vision problems. This is considered ocular hypertension. The nurse should ensure the patient is referred to an ophthalmologist for a comprehensive evaluation, as they are at high risk for developing glaucoma and optic nerve damage despite being asymptomatic.

How to Approach the Question

This is a factual recall question that tests knowledge of a standard physiological value.
First, identify the key concept in the question: 'normal intraocular pressure'.
Recall the standard range for this value from your studies, which is typically 10-21 mmHg.
Carefully evaluate each option against the recalled range.
Option B (10 to 20 mm of hg) is the closest and most inclusive fit to the standard 10-21 mmHg range.
Eliminate options that are clearly too low (hypotony) or too high (glaucoma).

Concept Tested & Keywords

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E6 Nursing Brunner Adult Health 3SA Vol 2 Part 1 p. 94-96

E6 Physiology Guyton 4SAE Part 3 p. 146-148

Practise the full AIIMS Rishikesh NO - 2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.