Abstract
Purpose: :
The association between ocular hypertension (OHT) or glaucoma and RVO has long been recognized. However, most studies examining this association have been cross-sectional or retrospective. The OHTS provides a unique opportunity to prospectively examine the association between OHT and RVO in individuals with moderately elevated intraocular pressure (IOP).
Methods: :
Incidence of RVO, defined as branch, central or hemicentral vein occlusions, were documented between February 1994 and July 1, 2005 among the 1636 subjects enrolled in the OHTS. Potential RVO events were identified by a keyword search of Adverse Event Reports, Endpoint Committee reviews, and by response to a written request for information sent to all 22 OHTS participating clinics. To confirm a potential RVO, we reviewed the complete OHTS charts, including disc and fundus photographs, and identified RVO subtype, eye, and probable date of onset. In cases requiring clarification, the individual clinic sites were contacted to provide additional information. For eye-specific analyses, we used the first affected eye of participants who had RVO in one or both eyes and one eye selected randomly of participants who did not have RVO.
Results: :
26 RVOs were identified and confirmed in 23 subjects - 5 branch, 14 central and 7 hemi-central RVOs. 1.8% (15/819) of the participants originally randomized to observation and 0.98 % (8/817) of those randomized to medication had a RVO. The 10 year cumulative incidence of RVO (first event) adjusted for different follow-up times was 2.1 % in the observation group and 1.4% in the medication group (Log-Rank p value 0.14).Participants who had a RVO were significantly older at baseline (65.1 versus 55.3 years, p=0.0001) and tended to be more hyperopic (spherical equivalent of +0.9 diopters greater than those who did not have a RVO (p=0.07)). There was no difference between those who did/did not develop RVO in terms of self-reported heart disease, hypertension, diabetes, or stroke at either baseline or throughout follow-up.
Conclusions: :
A trend for increased risk of RVO occurred in the observation group and in those with hyperopia. Age was a highly significant risk factor for RVO. Systemic conditions previously associated with RVOs did not achieve statistical significance. Overall, the small number of RVOs limited the power of analyses. The upper limit on IOP for inclusion in the study may have contributed to the low incidence of RVO observed.
Clinical Trial: :
www.clinicaltrials.gov NCT00000125
Keywords: clinical (human) or epidemiologic studies: prevalence/incidence • clinical (human) or epidemiologic studies: risk factor assessment • vascular occlusion/vascular occlusive disease