A 58-year-old man presents with sudden onset of floaters and flashing lights in the right eye for 2 days, followed by a shadow in the superior temporal field. On examination, visual acuity is 6/9, and there is no relative afferent pupillary defect. What is the investigation of choice to confirm the diagnosis?

## Investigation of Choice for Retinal Detachment ### Clinical Presentation The patient presents with classic features of acute retinal detachment: - Sudden onset of photopsia (flashing lights) - Floaters (vitreous hemorrhage or condensed vitreous) - Progressive visual field defect (shadow/curtain) - No RAPD (rules out optic nerve pathology) ### Gold Standard Investigation **Key Point:** Dilated fundus examination with indirect ophthalmoscopy is the gold standard and investigation of choice for diagnosing retinal detachment. **Clinical Pearl:** The indirect ophthalmoscope provides a wide field of view (approximately 45°), allowing visualization of the entire retina including the peripheral retina where most detachments occur. The 3-mirror Goldmann lens can be used for additional magnification if needed. ### Why Indirect Ophthalmoscopy? | Feature | Indirect Ophthalmoscopy | Direct Ophthalmoscopy | OCT | B-scan | |---------|------------------------|----------------------|-----|--------| | **Field of view** | 45° (wide) | 5-10° (narrow) | Axial only | Useful when media opaque | | **Peripheral retina visualization** | Excellent | Poor | Not applicable | Not applicable | | **Real-time assessment** | Yes | Yes | No (cross-section only) | No (ultrasound image) | | **Detachment confirmation** | Direct visualization | Limited | Cannot assess 3D extent | Useful if cataract/hemorrhage | | **Diagnostic accuracy** | 95-100% | Low | Low | High only if media opaque | **High-Yield:** In this case, the media is likely clear (VA 6/9, no mention of cataract or hemorrhage), so indirect ophthalmoscopy is both diagnostic and therapeutic (allows planning for retinal reattachment surgery). ### Role of Other Investigations **B-scan ultrasonography** is reserved for cases where the fundus view is obscured (dense cataract, vitreous hemorrhage, corneal opacity). It is not the first-line investigation when the media is clear. **OCT** provides cross-sectional imaging but cannot assess the full extent of detachment or peripheral retinal breaks. It is useful for post-operative assessment of macular involvement but not for initial diagnosis. **CT orbit** has no role in retinal detachment diagnosis; it is used for orbital pathology. ### Next Steps After Diagnosis Once detachment is confirmed, **B-scan** may be used to: - Assess the extent of detachment - Detect posterior vitreous detachment - Rule out intraocular foreign body or tumor [cite:Parson's Diseases of the Eye 22e Ch 12]