A 48-year-old woman with poorly controlled type 1 diabetes presents with sudden onset of floaters and blurred vision. On examination, there is a dense vitreous hemorrhage obscuring the fundal view. Visual acuity is hand movements only. Which investigation is most appropriate to assess the posterior segment and rule out retinal detachment?

## Investigation of Choice: B-Scan Ultrasonography **Key Point:** B-scan is the investigation of choice when media opacity (vitreous hemorrhage, dense cataract, corneal scarring) prevents visualization of the posterior segment. **High-Yield:** B-scan ultrasonography provides: - Real-time assessment of vitreous hemorrhage extent - Detection of retinal detachment (RD) — critical in diabetic retinopathy - Evaluation of optic nerve head and posterior pole - Assessment of choroidal thickness and posterior scleral contour - No radiation; non-invasive ## Clinical Context: Vitreous Hemorrhage in DR Dense vitreous hemorrhage in a diabetic patient raises concern for: 1. **Neovascularization of disc (NVD)** — source of bleeding 2. **Retinal detachment** — from tractional forces (tractional RD is common in PDR) 3. **Vitreous traction** — may require vitrectomy **Clinical Pearl:** In a diabetic with sudden VH and HM vision, ruling out RD is **urgent** because tractional RD can progress rapidly and cause permanent vision loss if untreated. ## Why B-Scan Is Optimal ```mermaid flowchart TD A[Dense vitreous hemorrhage]:::outcome --> B{Can visualize fundus?}:::decision B -->|No| C[B-scan ultrasonography]:::action C --> D[Assess RD, VH extent, PVD]:::outcome D --> E{RD present?}:::decision E -->|Yes| F[Urgent vitrectomy]:::urgent E -->|No| G[Manage VH medically/surgically]:::action B -->|Yes| H[Indirect ophthalmoscopy]:::action ``` ## Comparison of Investigations in Media Opacity | Investigation | Utility in VH | Limitation | | --- | --- | --- | | **B-scan** | ✓ Excellent — penetrates opaque media | Operator-dependent; lower resolution | | **Indirect ophthalmoscopy** | ✗ Cannot visualize posterior pole through dense VH | Requires clear media | | **FFA** | ✗ Fluorescein cannot reach retina through VH | Requires clear media; no structural detail | | **OCT-A** | ✗ Cannot image through dense hemorrhage | Requires clear media | **Mnemonic: "B-scan for Blocked view"** - **B**-mode ultrasound for opaque media - **Blocked** visualization by hemorrhage/cataract/scar - **Best** non-invasive assessment of posterior segment **Warning:** Do NOT attempt indirect ophthalmoscopy or scleral indentation when VH is too dense — you will not visualize the fundus and may delay diagnosis of RD.