Purpose:
To determine if there is any variation of intraocular pressure between the accommodated and non-accommodated state.
Methods:
Intraocular pressure (IOP) was measured in 94 eyes of 94 subjects using Goldmann applanation tonometry. Patients with a known diagnosis of open angle glaucoma, patients on any IOP lowering medication, had on slit lamp examination a shallow appearing anterior chamber, a peripheral iridotomy, or an anterior chamber or posterior chamber intraocular lens in either eye were all excluded. For each patient one eye was chosen at random. The patient was then instructed to read a Snellen chart at standard distance of 20 feet while the IOP was measured. Following this, the patient was instructed to read from a near card placed 14 inches. Only one eye from each patient was studied to ensure fixation was not affected by the exam. Differences between the two groups were analyzed using the Student's paired t-test. As in previous studies, a P value < 0.05 was considered statistically significant.
Results:
The average IOP (mmHg) for the non-accommodation group was 15.51. The average IOP for accommodation group was 15.48. The difference in IOP when accommodating was not statistically significant with a P value of 0.31. Out of the 94 eyes studied three showed an IOP rise of 1 mmHg, six showed an IOP decrease of 1 mmHg, and none showed a change greater than 1 mmHg.
Conclusions:
This study demonstrates that there is no variation of intraocular pressure when patients accommodate. Therefore, when measuring IOP during routine exams there is no need to ensure that patients are consistently fixating at a particular distance.
Keywords: intraocular pressure