A 40-year-old woman undergoes Goldmann applanation tonometry, which reads 18 mmHg. Her central corneal thickness is measured at 480 micrometers. What is the most likely implication of this finding?
- A The true intraocular pressure is higher than the recorded value ✓
- B The true intraocular pressure is lower than the recorded value
- C The reading is accurate because Goldmann tonometry is independent of corneal thickness
- D The reading is accurate because thin corneas compensate by flattening more easily
Correct answer: A. The true intraocular pressure is higher than the recorded value
Explanation
Goldmann applanation assumes a standard central corneal thickness of approximately 520 micrometers. A thinner-than-average cornea offers less resistance to applanation, so the tonometer underestimates the true pressure. With a thickness of 480 micrometers, the actual IOP is likely several mmHg above the recorded 18 mmHg. A thick cornea does the opposite, falsely elevating the reading, which is the error that must be excluded before labelling someone ocular hypertensive.
Reference: Khurana Comprehensive Ophthalmology / Parson's Diseases of the Eye, Latest Indian edition ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.