Canadian journal of ophthalmology. Journal canadien d'ophtalmologie

Pre- versus post-dilation changes in intraocular pressure: their clinical significance.

PMID 23036547


To measure the difference in intraocular pressure (IOP) before and following pharmacologic mydriasis with a cycloplegic-mydriatic combination agent in normal subjects using the Goldmann applanation tonometer. A prospective, university hospital-based, nonrandomized interventional case series. We recruited 67 normal subjects without glaucoma. Data were collected on the patients' IOPs before and 45 minutes after pharmacologic mydriasis in both eyes using the Goldmann applanation tonometer. Central corneal thickness and additional parameters were measured to further confirm the absence of glaucoma and to study the correlation between IOP fluctuations and these characteristics. The IOP was measured in 127 eyes. The mean difference between pre- and post-dilation time points was 1.1 ± 2.5 mm Hg in the right eye and 0.7 ± 2.3 mm Hg in the left eye. Post-dilation, the maximum deviation was a change of 6 mm Hg.; 35% of patients had a post-dilation variation of >2 mm Hg (clinically significant). Of these, 31.1% of changes were IOP increases, and 68.9% of changes were IOP decreases after dilation. Central corneal thickness and other parameters showed no correlation with IOP changes. The use of pharmacologic mydriasis prior to IOP measurement affected the reliability of IOP measurements taken post-dilation in our group of patients. Thus, we believe that the stringent measurement of IOP prior to dilation is the responsible method of measuring and following IOP in every single patient.