A 62-year-old highly myopic man presents with sudden onset of floaters and temporal flashes. Slit-lamp examination reveals pigmented cells ('tobacco dust') in the anterior vitreous, and dilated fundus examination with scleral indentation shows a posterior vitreous detachment with a Weiss ring. The structure marked **A** in the diagram is identified as the source of his symptoms. Which of the following best describes the pathophysiology of this lesion and its relationship to his presenting complaints?

Question

Accepted Answer

C. A U-shaped horseshoe tear with vitreoretinal traction at the apex, causing vitreous hemorrhage from torn retinal vessels and photopsia from vitreous traction on the retina. ## Why option 1 is correct

The structure marked **A** is a U-shaped horseshoe retinal tear in the superotemporal periphery with vitreoretinal traction at the apex (flap). This morphology is pathognomonic for a tractional tear caused by vitreous traction. The traction on the tear apex causes rupture of retinal vessels at the tear margin, leading to vitreous hemorrhage (manifesting as the "shower of black floaters" and "tobacco dust" on slit-lamp examination). The mechanical traction also stimulates photoreceptors, causing the characteristic flashes of light (photopsia) in the temporal periphery. This is the classic presentation of a horseshoe tear with acute vitreous hemorrhage in a highly myopic patient with posterior vitreous detachment. Per Ryan's Retina, 6th Edition, horseshoe tears are the most common type of retinal break associated with rhegmatogenous retinal detachment and require urgent laser retinopexy to prevent progression.

## Why each distractor is wrong

- **Option 2 (Round atrophic hole)**: Round holes lack the U-shaped morphology and vitreoretinal traction characteristic of horseshoe tears. They typically occur in areas of lattice degeneration and cause gradual, asymptomatic vision loss rather than acute floaters and photopsia. Round holes are not associated with acute vitreous hemorrhage.

- **Option 3 (Complete PVD with no adhesion)**: While this patient does have a posterior vitreous detachment with a Weiss ring, the horseshoe tear is defined by the presence of residual vitreous traction at the apex—not complete detachment. Complete detachment without traction would not explain the acute photopsia or the mechanism of vessel rupture causing floaters.

- **Option 4 (Photocoagulation scar)**: A scar from previous treatment would not present acutely with floaters and flashes, nor would it show "tobacco dust" in the anterior vitreous or pigmented cells indicating active retinal break. Scars are chronic, stable lesions without acute inflammatory signs.

**High-Yield:** Horseshoe tears = U-shaped morphology + vitreous traction at apex + acute floaters (hemorrhage) + photopsia (traction) + high risk of RRD → urgent laser retinopexy.

[cite: Ryan's Retina, 6th Edition, Chapter on Rhegmatogenous Retinal Detachment]

Answer

A. A peripheral retinal scar from previous photocoagulation, causing chronic photopsia without acute symptoms or vitreous inflammation

Answer

B. A retinal break with complete posterior vitreous detachment and no residual vitreous adhesion, resulting in immediate macula-off detachment

Answer

D. A round atrophic hole in the retina with minimal vitreous traction, typically causing gradual vision loss without acute floaters

Explanation

Practice similar questions

Join our NEET PG community

Why option 1 is correct

Why each distractor is wrong