A patient comes to the ophthalmologist OPD and the doctor advises a Snellen test. What is the purpose of this test?

Appeared in: SGPGI Nursing Officer-2024

Explanation

The Snellen test is the standard method for measuring distant visual acuity, which is the clarity of vision from a distance.
The procedure involves having the patient read progressively smaller letters on a chart from a standardized distance of 20 feet (or 6 meters).
Its primary purpose is to detect refractive errors like myopia (nearsightedness), where distant objects appear blurry.
The results are recorded as a fraction (e.g., 20/20, 20/40) to quantify the patient's ability to see compared to a standard of normal vision.

Option B: Colour vision is not assessed by the Snellen chart. It is a test of acuity, not color perception.
Option C: The Snellen test is specifically for distant vision. Near vision is tested differently.
Option D: Blurred vision is a subjective symptom or a patient complaint, not an objective parameter that a test measures. The Snellen test quantifies the degree of visual acuity, which helps to understand the cause of the blurriness.

Clinical Relevance

Nursing practice connection: Use the key finding related to Assessment of Visual Acuity using Snellen Chart to guide bedside assessment, documentation, and the next nursing action.
A baseline Snellen test is a fundamental part of a health assessment, helping to identify patients who need corrective lenses (glasses or contacts) or further ophthalmological evaluation.
Nurses often perform initial vision screenings in schools, clinics, and occupational health settings using the Snellen chart to detect vision problems early.
What if? If a patient is a child who cannot read letters, the nurse would use a chart with pictures (like LEA symbols) or a Tumbling E chart (where the child points in the direction the 'E' is facing) to assess distant visual acuity.

How to Approach the Question

Identify the key term in the question stem, which is 'Snellen test'.
Access your knowledge about common diagnostic tools used in an ophthalmology setting.
Recall that the Snellen chart is the large chart with letters of decreasing size typically seen on the wall of a doctor's office.
Associate the placement and use of this chart (reading from a distance) with its purpose.
Evaluate the options: 'Distant vision' directly corresponds to the function of reading a chart from across a room.
Eliminate the other options by recalling the specific tests for them: Ishihara plates for color vision and Jaeger cards for near vision. Recognize that 'blurred vision' is a symptom, not a test's purpose.

Concept Tested & Keywords

Concept Tested: Assessment of Visual Acuity using Snellen Chart
Stem keywords: Snellen test, ophthalmologist, purpose
Lead-in keywords: What is the purpose
Clinical cues: The care setting changes urgency, monitoring level, and the expected nursing action.
Negative lead-in flag: false

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E6 Nursing Fundamentals Potter Perry 12e Part 3 p. 78-80

E6 Medicine Harrison 22e Part 1 p. 262-264

Practise the full SGPGI Nursing Officer-2024

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