A 52-year-old woman with a history of hypertension and diabetes presents with sudden-onset loss of the upper half of the visual field in both eyes. She denies any eye pain or diplopia. Visual acuity is 6/6 in both eyes. Confrontation visual fields show loss of the superior visual fields bilaterally (above the horizontal meridian), with the inferior fields intact. Fundoscopy reveals flame-shaped hemorrhages and cotton-wool spots in the inferior retina bilaterally. MRI brain is normal. What is the most likely diagnosis?

Explanation

## Altitudinal Visual Field Defect with Retinal Hemorrhages **Key Point:** The patient has **loss of the superior visual fields bilaterally** (above the horizontal meridian) with **intact inferior fields** — this is **superior altitudinal hemianopia**. The fundoscopic findings of inferior retinal hemorrhages and cotton-wool spots confirm retinal pathology, not intracranial disease. ### Anatomical-Clinical Correlation Altitudinal hemianopia is characterized by loss of either the superior or inferior half of the visual field along the horizontal meridian. This defect is typically caused by **vascular occlusion at the level of the optic nerve or retina**, where the superior and inferior vascular territories are anatomically distinct. ### Mechanism in This Case 1. **Inferior retinal hemorrhages and cotton-wool spots** indicate ischemia in the inferior retina 2. **Superior visual field loss** results because the inferior retina (which processes the superior visual field via inverted retinal image) is ischemic 3. **Bilateral presentation** suggests bilateral retinal vascular insufficiency, common in severe diabetic retinopathy or hypertensive retinopathy 4. **Normal MRI brain** excludes intracranial lesions ### Differential Diagnosis: Altitudinal vs. Other Field Defects | Feature | Superior Altitudinal | Inferior Altitudinal | Quadrantanopia | Homonymous Hemianopia | |---------|----------------------|----------------------|-----------------|----------------------| | **Pattern** | Loss above horizontal | Loss below horizontal | One quadrant loss | Entire half loss | | **Anatomy** | Optic nerve/retina | Optic nerve/retina | Optic radiations | Optic tract/LGN/cortex | | **Typical Cause** | CRAO, AION, retinopathy | CRAO, AION, retinopathy | Temporal/parietal stroke | Posterior circulation stroke | | **Fundoscopy** | Abnormal (hemorrhages, pallor) | Abnormal (hemorrhages, pallor) | Normal | Normal | | **MRI Brain** | Normal | Normal | Abnormal | Abnormal | **High-Yield:** **Altitudinal hemianopia = retinal/optic nerve disease**; **Quadrantanopia/hemianopia = post-chiasmal (brain) disease**. The fundoscopic findings are the key discriminator here. **Clinical Pearl:** In diabetic and hypertensive patients, severe retinopathy can cause bilateral altitudinal defects due to ischemia in the distribution of the superior or inferior temporal arteries. The horizontal meridian represents the boundary between these vascular territories. **Mnemonic: AION** — Arteritic Ischemic Optic Neuropathy (giant cell arteritis) or non-arteritic AION; **CRAO** — Central Retinal Artery Occlusion; both present with altitudinal field loss and abnormal fundoscopy.