Which of the following are common errors when obtaining IOP measurements?

• A. Globe compression with lid margin retraction causing false elevations
• B. Occluding jugular vein during restraint causing false elevations
• C. Both A and B
• D. Neither A nor B

Answer: (C)

IOP readings are highly sensitive to technique because the measurement depends on accurately assessing the pressure inside the eye without adding external forces. If the globe is compressed or the lid margins are retracted, external pressure can squeeze the eye or alter the corneal surface, making the reading higher than the true intraocular pressure. Similarly, occluding the jugular vein during restraint raises venous pressure in the head and increases episcleral venous pressure, which impedes aqueous humor outflow. This back-pressure elevates the measured IOP even if the true pressure hasn’t changed. Because both maneuvers can produce artificially elevated readings, they are common sources of false elevations. The correct approach is gentle handling to avoid globe compression, minimal lid manipulation, comfortable restraint that does not impede venous drainage, and, if needed, repeating measurements or using alternative tonometry methods to confirm.