What is the OHTS risk calculator?
The OHTS risk calculator is designed to estimate the chance that a person with ocular hypertension may develop primary open-angle glaucoma over a 5-year period. OHTS stands for the Ocular Hypertension Treatment Study, a landmark trial that helped clinicians identify which patients are at higher risk and may benefit from earlier treatment.
Instead of relying on just one number, this risk approach combines multiple data points from your eye exam. That combination gives a more useful estimate than intraocular pressure alone.
Inputs used in this calculator
1) Age
Risk generally increases with age. Older patients with otherwise similar measurements tend to have a higher projected conversion risk.
2) Untreated intraocular pressure (IOP)
IOP is one of the key risk factors. Higher untreated pressure values raise estimated risk, especially when paired with thinner corneas or suspicious optic nerve findings.
3) Central corneal thickness (CCT)
Thinner corneas are associated with higher conversion risk. CCT is measured in microns using pachymetry and is one of the most influential factors in many risk models.
4) Vertical cup-to-disc ratio (VCDR)
This optic nerve measurement reflects cup size relative to disc size. Larger ratios can indicate structural vulnerability or existing glaucomatous change risk.
5) Pattern standard deviation (PSD)
PSD comes from visual field testing and can capture focal irregularities in the field. Higher values may suggest greater functional risk.
How to use the ohts risk calculator correctly
- Use recent measurements from a full eye exam.
- Enter values for the same eye (right or left) consistently.
- Prefer untreated IOP when available.
- Repeat calculations if your clinician updates measurements over time.
- Interpret results in context with gonioscopy, optic disc imaging, and family history.
Understanding your result
The calculator gives an estimated 5-year risk percentage plus a simple risk category:
- Low: usually monitored with periodic follow-up.
- Moderate: individualized discussion about treatment versus close observation.
- High: often prompts stronger consideration of pressure-lowering therapy.
There is no universal threshold that applies to every patient. Treatment decisions depend on life expectancy, medication tolerance, baseline optic nerve appearance, adherence, and patient preference.
Why risk-based care matters in ocular hypertension
Not every person with elevated IOP develops glaucoma. Risk calculators help avoid overtreating low-risk patients while identifying those who may benefit from early intervention. This improves precision, supports shared decision-making, and can reduce long-term vision loss risk.
Important limitations
- This is an educational implementation and not an official clinical decision tool.
- Measurements can vary by instrument and examiner.
- Single time-point data may miss trends that matter clinically.
- Other factors (race/ethnicity, family history, angle anatomy, disc hemorrhage) also influence risk.
- Only an eye-care professional can diagnose glaucoma or start treatment safely.
When to see an eye specialist urgently
Seek prompt care if you notice rapidly worsening vision, significant eye pain, halos with headache/nausea, or sudden visual field loss. These symptoms are not handled by this calculator and require direct medical evaluation.
Bottom line
The ohts risk calculator is a practical way to turn several exam measurements into a single, understandable 5-year risk estimate. Use it to prepare better questions for your optometrist or ophthalmologist, not as a standalone diagnosis. The best plan is always personalized.