Abstract
Purpose: :
Intraocular pressure (IOP) variation contributes to glaucoma progression. Sources of IOP variation include circadian rhythm, ocular disease, and physiological factors. Under physiological factors, the effect of body position on habitual IOP variation in controls and patients with glaucoma and ocular hypertension has been compared. Our objective is to evaluate the habitual IOP variation in patients who have blebs after trabeculectomy.
Methods: :
This is a prospective study to examine habitual IOP in seated and supine positions. Inclusion criteria included: trabeculectomy, greater than six months postoperative follow up, and presence of bleb. Exclusion criteria included: no bleb following trabeculectomy and less than six months follow–up. The habitual IOPs were measured as follows: 1) seated IOP measured by Goldmann applanation, 2) seated IOP measured by pneumotonometry, then 3) after at least 5" supine position, supine IOP measured by pneumotonometry. Data collection included: demographic information, surgeries, ocular medications, early post–operative IOP variation, habitual IOPs, and bleb morphology using the Indiana Bleb Appearance Grading Scale (IBAGS). Differences in habitual IOP were analyzed by paired Student t test.
Results: :
In 12 eyes from 8 patients, the mean IOPs were 11.0 + 5.2 mm Hg sitting by Goldmann applanation, 14.2 + 5.4 mm Hg sitting by pneumotonometry, and 19.2 + 5.8 mm Hg supine by pneumotonometry. The average change (IOPsupine – IOPsitting) in habitual IOP was 5.0 + 1.9. The range of habitual IOP change was 1.3 to 8.0 mm Hg. Differences between sitting and supine pneumatic measurements were statistically significant (p<0.00001), as were the differences between sitting applanation and pneumatic IOPs (p<0.001). It appears qualitatively that the degree of bleb vascularity judged by IBAGS is associated with large habitual IOP fluctuation.
Conclusions: :
In this preliminary study on habitual IOP variation in eyes with blebs after trabeculectomy, our findings suggest that IOP variation may be an important consideration for patients with functional filters.
Keywords: intraocular pressure • clinical (human) or epidemiologic studies: risk factor assessment • clinical (human) or epidemiologic studies: outcomes/complications