Why obtain multiple untreated IOP measurements before starting treatment?

• A. It confirms diagnosis
• B. IOP fluctuates over 24 hours
• C. It doesn't matter
• D. It correlates with vision

Answer: (B)

Intraocular pressure varies over the day and night, with peaks that can be easily missed by a single reading. Obtaining multiple untreated measurements provides a true picture of the pressure range, including any peak values, which is crucial for assessing risk and deciding whether treatment is needed and how aggressively to treat. Measuring before starting therapy establishes an accurate baseline, so later changes can be attributed to disease progression or the effect of treatment. A single reading can be influenced by the time of day, posture, corneal properties, and measurement variability, making it unreliable for guiding decisions. Vision or damage doesn’t correlate perfectly with a lone IOP value, and glaucoma cannot be diagnosed from one measurement alone; the goal is to capture diurnal variation and establish a solid baseline.