Which ophthalmic diagnostic test measures the Intraocular pressure?

Appeared in: AIIMS Raipur NO - 2019 (Shift-1)

Explanation

Tonometry is the specific procedure for measuring the pressure within the eye, known as intraocular pressure (IOP).
It is an essential component of a comprehensive eye exam, particularly for screening and monitoring glaucoma.
The most common method is applanation tonometry, which measures the force needed to temporarily flatten a part of the cornea.
Normal IOP typically ranges from 10 to 21 mmHg; elevated levels are a key risk factor for glaucoma.

Option B: Perimetry does not measure pressure; it assesses the visual field to map out a person's peripheral and central vision.
Option C: Gonioscopy is a qualitative examination to visualize the eye's drainage angle, not a quantitative measurement of pressure.
Option D: The Amsler grid is a tool for self-monitoring central vision and does not measure intraocular pressure.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Measurement of Intraocular Pressure (IOP) as background academic context rather than a clinical decision trigger.
Routine tonometry is a cornerstone of preventative eye care, as glaucoma is often asymptomatic in its early stages (the 'silent thief of sight'). Early detection through IOP measurement allows for timely intervention to prevent irreversible blindness.
Nurses play a key role in educating patients before tonometry, advising them to avoid squeezing their eyelids, holding their breath, or performing a Valsalva maneuver, as these actions can falsely elevate the IOP reading.
What if? If a patient has a consistently high IOP (e.g., greater than 21 mmHg) but a normal optic nerve and visual field, the diagnosis is ocular hypertension, not glaucoma. These patients require close monitoring, as they are at higher risk of developing glaucoma, but may not need immediate treatment.

How to Approach the Question

First, identify the key phrase in the question: 'measures the Intraocular pressure'.
This is a factual recall question that requires knowledge of common ophthalmic diagnostic tests.
Review the options and recall the specific function of each test.
Match the function 'measuring pressure' to the correct term. Tonometry is the direct measurement of 'tonus' or pressure.
Eliminate the other options by recalling their distinct purposes: Perimetry (visual field), Gonioscopy (drainage angle), and Amsler grid (central vision/macula).

Concept Tested & Keywords

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E6 Nursing Brunner Adult Health 3SA Vol 2 Part 1 pp. 86-88, 87-89, 96-98

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