Tonometry test of eye measures?

Appeared in: TMC Staff Nurse - 2019

Explanation

Tonometry is the standard procedure for measuring the pressure inside the eye, known as intraocular pressure (IOP).
The test is a critical component of eye examinations, primarily used to screen for and monitor glaucoma.
Elevated IOP is a major risk factor for glaucoma, a condition that can cause progressive damage to the optic nerve, leading to irreversible vision loss.
The normal range for intraocular pressure is generally considered to be between 10 and 21 millimeters of mercury (mmHg).

Option A: This is incorrect. The test for peripheral vision is called perimetry or a visual field test.
Option C: This is incorrect. Visual acuity, or the sharpness of central vision, is measured using a Snellen or LogMAR eye chart.
Option D: This is a vague and non-standard description of an eye test. Tonometry measures the static pressure, not the eye's response to a sudden increase in pressure.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Purpose of Tonometry as background academic context rather than a clinical decision trigger.
Nurses play a key role in preparing patients for tonometry, explaining the procedure (e.g., the 'puff of air' in non-contact tonometry) to reduce anxiety and ensure cooperation.
For applanation tonometry, which requires anesthetic drops, the nurse must instruct the patient not to rub their eyes afterward to prevent corneal abrasion while the eye is numb.
An IOP reading is a vital sign for the eye. Consistently high readings are a red flag for glaucoma, requiring referral to an ophthalmologist for further evaluation and management.

How to Approach the Question

First, identify the key term in the question stem, which is 'Tonometry test'.
Recall the specific function of this diagnostic procedure from your medical knowledge. Tonometry is fundamentally about measuring pressure.
Evaluate each option based on this core function.
Option A refers to peripheral vision, which is tested by perimetry.
Option B refers to intraocular pressure, which is the direct purpose of tonometry.
Option C refers to visual acuity, which is tested with eye charts like the Snellen chart.

Concept Tested & Keywords

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E6 Nursing Brunner Adult Health 3SA Vol 2 Part 1 p. 86-88

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

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