A 52-year-old Indian woman is referred to the glaucoma clinic after a routine eye check-up at an optical shop revealed elevated intraocular pressure. She is completely asymptomatic with no visual complaints. On examination, IOP is 28 mmHg in the right eye and 26 mmHg in the left eye. Gonioscopy shows Shaffer grade 3 angles bilaterally with normal trabecular meshwork. Optic disc photographs show a horizontal cup-to-disc ratio of 0.5 with intact neuroretinal rims, no pallor, and no disc hemorrhages. Automated perimetry (24-2 SITA Standard) is normal in both eyes. What is the diagnosis?

Explanation

## Diagnosis: Ocular Hypertension (OHT) ### Diagnostic Criteria for Ocular Hypertension **Key Point:** Ocular hypertension is defined as **elevated IOP (>21 mmHg) in the absence of optic nerve head damage and visual field defects** in a structurally normal eye with an open angle. ### Differential Diagnosis: OHT vs. POAG | Feature | Ocular Hypertension | Primary Open-Angle Glaucoma | |---------|-------------------|----------------------------| | **IOP** | Elevated (>21 mmHg) | Elevated (>21 mmHg) | | **Angle** | Open | Open | | **Optic nerve head** | Normal (CDR <0.5, intact rim) | Abnormal (CDR >0.5, rim thinning, pallor, hemorrhage) | | **Visual field** | Normal | Defective (arcuate scotoma, nasal step, paracentral) | | **Diagnosis** | Elevated IOP alone | IOP + structural/functional damage | | **Progression to glaucoma** | 1–2% per year (Ocular Hypertension Treatment Study) | **High-Yield:** OHT is a **risk factor for glaucoma**, not glaucoma itself. The distinction is critical because it changes management strategy. ### Why NOT Primary Open-Angle Glaucoma? **Key Point:** POAG requires **both** elevated IOP **and** evidence of optic nerve damage (structural) **and/or** visual field defect (functional). This patient has: - ✓ Elevated IOP (28 and 26 mmHg) - ✗ Normal optic disc (CDR 0.5, intact rims, no pallor, no hemorrhage) - ✗ Normal visual field (24-2 SITA Standard) Without optic nerve or visual field damage, the diagnosis cannot be POAG, regardless of IOP elevation. ### Ocular Hypertension Treatment Study (OHTS) Evidence ```mermaid flowchart TD A[Ocular Hypertension]:::outcome --> B{Treat or observe?}:::decision B -->|Observation| C[Annual eye exams + VF testing]:::action B -->|Treatment| D[Topical IOP-lowering agents]:::action C --> E{Progression to POAG?}:::decision D --> F{Progression to POAG?}:::decision E -->|Yes ~4.4% over 5 years| G[Initiate/escalate therapy]:::action E -->|No| H[Continue observation]:::action F -->|Yes ~1.5% over 5 years| G F -->|No| I[Continue therapy]:::action ``` **Clinical Pearl:** The OHTS (2002) demonstrated that **early treatment of OHT reduces the risk of progression to POAG by ~50%**, but many patients never develop glaucoma. Treatment decisions should be individualized based on risk factors (age, family history, vertical CDR, IOP level, central corneal thickness). ### Risk Factors for Progression from OHT to POAG 1. **Older age** (>60 years) 2. **Higher baseline IOP** (>26 mmHg) 3. **Thinner central corneal thickness** (<555 μm) 4. **Larger vertical CDR** (>0.4) 5. **Positive family history** of glaucoma 6. **African or Hispanic ethnicity** This patient has IOP 26–28 mmHg and age 52, warranting closer monitoring. ### Management of Ocular Hypertension **High-Yield:** Management is **individualized** based on risk stratification: - **Low-risk OHT:** Observation with annual IOP measurement, optic disc photography, and visual field testing - **High-risk OHT** (multiple risk factors): Consider initiating topical IOP-lowering therapy to reduce progression risk - **All OHT patients:** Lifestyle modifications (exercise, weight loss, caffeine reduction), patient education, and regular follow-up ### Why NOT Normal-Tension Glaucoma? Normal-tension glaucoma (NTG) is characterized by **optic nerve damage and/or visual field defects with IOP consistently ≤21 mmHg**. This patient has elevated IOP and no optic nerve damage—NTG does not fit. ### Why NOT Secondary Glaucoma Due to Pigment Dispersion? Pigment dispersion syndrome (PDS) presents with **Krukenberg spindle, pigment on trabecular meshwork, and transillumination defects** on slit-lamp examination. Gonioscopy in this patient shows **normal trabecular meshwork**—no pigment deposition is described. Secondary pigmentary glaucoma is not supported by the clinical findings.