Following recent-onset flashes and floaters, slit-lamp examination with a three-mirror lens reveals pigmented cells floating in the anterior vitreous. What is this sign called and what does it suggest?
- A Shafer positive sign, suggesting a retinal break ✓
- B Hruby negative sign, excluding vitreous pathology
- C Amsler sign, suggesting Fuchs heterochromic iridocyclitis
- D Seidel positive test, indicating wound leak
Correct answer: A. Shafer positive sign, suggesting a retinal break
Explanation
Tobacco dust, also known as Shafer sign, describes pigment granules liberated from disruption of the retinal pigment epithelium at the site of a retinal tear and dispersed in the anterior vitreous. Its presence strongly supports a retinal break and mandates careful indirect ophthalmoscopy with scleral depression to locate and treat the tear. Amsler sign refers to blood in Schlemm canal in Fuchs uveitis syndrome, and Seidel testing detects aqueous leakage from a corneal or scleral wound.
Reference: Kanski's Clinical Ophthalmology, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.