When to Start Drops in OHT with IOP 25 mmHg
Start drops if ≥2% annual POAG risk using OHTS calculator; otherwise observe with 6-12 month follow-up intervals.
Risk Stratification Approach
The decision to treat ocular hypertension at IOP 25 mmHg hinges on calculating the 5-year risk of conversion to primary open-angle glaucoma using validated risk factors 1. The most recent AAO guidelines (2021) recommend using the OHTS risk calculator available at https://ohts.wustl.edu/risk/ 1.
Key Risk Factors to Assess
The five major predictors from OHTS that determine treatment timing are 2:
- Age (older = higher risk)
- Vertical cup-to-disc ratio (larger = higher risk)
- Pattern standard deviation on visual field (higher = higher risk)
- Central corneal thickness (thinner = higher risk)
- Baseline IOP level (your patient at 25 mmHg)
Additional risk factors include 3, 4:
- African American or Latino/Hispanic ethnicity
- Family history of glaucoma
- Myopia
- Disc hemorrhage
- Male sex
Treatment Thresholds
Treat if annual risk ≥2%: Cost-effectiveness analysis demonstrates that treating patients with ≥2% annual POAG risk is cost-effective at 42,430 USD/QALY, well below the 50,000-100,000 USD/QALY threshold 5. This translates to approximately 10% 5-year risk on the OHTS calculator.
Observe if annual risk <2%: Most OHT patients without significant risk factors can be safely monitored without treatment 4. The OHTS showed only 4.4% of untreated patients developed POAG at 5 years versus 9.5% at 10 years 2.
First-Line Treatment When Indicated
Prostaglandin analogs are the preferred initial therapy 6, 1. They provide the most efficacious IOP reduction (20-30%), require once-daily dosing, and have the best tolerability profile 7, 6. Specifically, bimatoprost, latanoprost, and travoprost show superior efficacy 7.
Target IOP: Aim for 20% reduction from baseline (target ~20 mmHg for your patient) 1. However, if baseline IOP is markedly elevated, 20% may be insufficient 1.
Monitoring Protocol
If observing without treatment 1:
- Follow every 6-12 months for low-risk patients
- Follow every 3-6 months if multiple risk factors present
- Repeat OCT/RNFL imaging and visual fields annually
- Reassess risk at each visit
If treating 1:
- Follow every 2-8 weeks initially until target IOP achieved
- Then every 6-12 months once stable
- Monitor for medication side effects and adherence
Common Pitfalls
The evidence shows that delaying treatment until damage occurs is unnecessarily conservative when risk factors are present 5. However, treating all OHT patients regardless of risk is both costly and less effective than risk-stratified approaches 5. The key is using the validated OHTS calculator rather than clinical gestalt alone 1.
Selective laser trabeculoplasty is an alternative first-line option showing comparable efficacy to drops 1, particularly useful for patients with adherence concerns.