A 58-year-old man presents with sudden onset of severe eye pain, blurred vision, and a red eye for 2 days. He has a history of type 2 diabetes mellitus for 10 years with poor glycemic control (HbA1c 9.2%). On examination, visual acuity is 6/60 in the affected eye. Slit-lamp examination reveals a hazy cornea, shallow anterior chamber, and rubeosis iridis. Intraocular pressure (IOP) is 48 mmHg. Fundoscopy shows extensive retinal hemorrhages and cotton-wool spots. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Neovascular Glaucoma ### Key Findings in This Case **Key Point:** The combination of rubeosis iridis (abnormal new vessels on the iris), elevated IOP, extensive retinal hemorrhages, and cotton-wool spots in a poorly controlled diabetic patient is pathognomonic for neovascular glaucoma (NVG) secondary to proliferative diabetic retinopathy (PDR). ### Pathophysiology of Neovascular Glaucoma ```mermaid flowchart TD A[Severe retinal ischemia<br/>PDR/CRVO/OIS]:::outcome --> B[VEGF release from<br/>ischemic retina]:::outcome B --> C[Neovascularization of iris<br/>and angle structures]:::action C --> D[Angle closure + elevated IOP]:::urgent D --> E[Neovascular Glaucoma]:::outcome F[Cotton-wool spots<br/>Retinal hemorrhages] -.->|Signs of| A G[Rubeosis iridis] -.->|Sign of| C ``` ### Distinguishing Features of NVG | Feature | Neovascular Glaucoma | Acute Angle-Closure | Phacomorphic | |---------|----------------------|---------------------|---------------| | **Iris appearance** | Rubeosis iridis (new vessels) | Normal iris, mid-dilated pupil | Normal iris | | **Retinal findings** | Hemorrhages, cotton-wool spots, ischemia | Usually normal fundus | Normal fundus | | **Anterior chamber** | Shallow (due to neovascular membrane) | Shallow (pupillary block) | Shallow (large lens) | | **Cause** | Retinal ischemia (PDR, CRVO, OIS) | Pupillary block | Intumescent cataract | | **Corneal clarity** | Initially hazy | Hazy (corneal edema) | Hazy (corneal edema) | **High-Yield:** Rubeosis iridis is the hallmark sign of neovascular glaucoma and distinguishes it from other secondary glaucomas. ### Risk Factors for NVG in Diabetics 1. Poor glycemic control (HbA1c > 8%) 2. Presence of proliferative diabetic retinopathy (PDR) 3. Extensive retinal ischemia and hemorrhage 4. Prolonged duration of diabetes ### Management Approach **Clinical Pearl:** Early recognition and aggressive management of the underlying retinal ischemia is crucial. Treatment includes: - Aggressive IOP-lowering medications (prostaglandin analogs, beta-blockers, carbonic anhydrase inhibitors) - Panretinal photocoagulation (PRP) to reduce VEGF production - Anti-VEGF intravitreal injections (bevacizumab, ranibizumab, aflibercept) - Cyclodestructive procedures if medical/laser therapy fails **Warning:** NVG is a difficult-to-treat glaucoma with poor prognosis if not managed promptly. Delay in treatment can lead to permanent vision loss and even phthisis bulbi. [cite:Khurana Comprehensive Ophthalmology Ch 12]