Abstract
Purpose: :
To determine the effect of orbital decompression on intraocular pressure in patients presenting with type 2 restrictive Graves disease. Patients with type 2 Graves are more prone to optic neuropathy and glaucoma. The optic neuropathy and glaucoma have been attributed to a lack of orbital space due to increased orbital volume. A review of the literature revealed no study examining the intraocular pressure changes that occur in Graves' patients.
Methods: :
This is a retrospective study of 21 Graves patients at Midwest Eye Institute and Roudebush VA medical center. All patients were under the care of one of three doctors. Measurement of intraocular pressure was preformed in primary gaze and upgaze by tonometry applanation by one of the three doctors. Measurement in upgaze was specifically chosen since the inferior rectus muscle is the most frequently affected muscle in Graves' patients. All patients had their decompression surgeries between 11/03 and 10/05. Two wall decompressions (inferior and medial wall) were preformed by one of two surgeons. 2 patients were excluded from the study due to their initial presentations with acute optic neuropathy.
Results: :
Primary outcome demonstrated a marked increase in intraocular pressure during upgaze in those patients with type 2 Graves disease. These same patients demonstrated a significant drop of intraocular pressure during upgaze after two–wall orbital decompression. There was a notable diffference in the intraocular pressure during upgaze comparing those patients that required surgery and those that did not. Paired T–test was preformed on intraocular pressure measurements in the pre and post surgery patients with a P–value of 0.001 for the right eye and 0.006 for the left eye. The upgaze measurements were also compared between the group that required surgery for their disease and the group that did not. This was also statistically significant, with a P–value of 0.001 for the right eye and 0.005 for the left eye. Hertel measurements between the two groups were not statistically significant.
Conclusions: :
There is a significant decrease in the intraocular pressures during upgaze when comparing pre and post decompression measurements in patients with type 2 Graves disease. Intraocular pressure in primary gaze was not elevated nor did it change significantly with decompression. Based on our findings in this study, upgaze tonometry readings should be considered in the initial work–up of patients with Graves disease.
Keywords: anatomy • extraocular muscles: structure • orbit