What is the most appropriate documentation of visual acuity for a 58-year-old man with sudden painless blurring of vision in the right eye (OD) who cannot read the largest Snellen line at 20 feet but can correctly identify the largest optotype at 5 feet?

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Last updated: September 19, 2026 • View editorial policy

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Visual Acuity Documentation: 5/200 OD

The correct documentation is C. 5/200 OD - this represents the standardized Snellen notation when a patient can identify the largest optotype (typically the 200-foot letter) at 5 feet instead of the standard 20 feet.

Understanding Snellen Notation

The Snellen fraction works as follows:

  • Numerator = the distance at which the patient was tested
  • Denominator = the distance at which a person with normal vision could read that same line

In this case:

  • The patient was moved to 5 feet (numerator)
  • He correctly identified the largest optotype, which is designed to be read at 200 feet by someone with normal vision (denominator)
  • Therefore: 5/200

Why the Other Options Are Incorrect

Option A (20/200 OD) would only be correct if the patient could read the largest line while standing at the standard 20-foot distance. Since he couldn't read it at 20 feet, this is inaccurate.

Option B (20/400 OD) is mathematically equivalent to 5/100, not 5/200. This would apply if he read a smaller optotype (the 400-foot letter) at 20 feet, or the 100-foot letter at 5 feet.

Option D (Counting fingers at 5 feet) is reserved for patients who cannot identify optotypes at all, even when brought closer. This patient successfully identified the optotype, so formal Snellen notation applies.

Clinical Significance

This visual acuity of 5/200 indicates severe visual impairment 1. According to ophthalmology guidelines, severe visual impairment is defined as best-corrected visual acuity less than 20/160 to 20/400 1. This patient's acuity falls within this range and approaches the threshold for legal blindness (20/200) 2.

Critical Next Steps

Given the sudden, painless vision loss in a 58-year-old man, urgent ophthalmologic evaluation is essential to rule out:

  • Retinal artery occlusion
  • Retinal detachment
  • Vitreous hemorrhage
  • Optic neuropathy

The sudden onset and severity warrant same-day ophthalmology referral 3.

References

3
Research

Sudden Vision Loss: A Diagnostic Approach.

American family physician, 2025

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.