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F. A. Medeiros, D. Ng, L. M. Zangwill, P. A. Sample, R. N. Weinreb; Long-Term Intraocular Pressure Fluctuations and Risk of Conversion From Ocular Hypertension to Glaucoma. Invest. Ophthalmol. Vis. Sci. 2007;48(13):851.
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To investigate whether long-term intraocular pressure (IOP) fluctuations are a risk factor for conversion from ocular hypertension to glaucoma.
The study included 105 patients with ocular hypertension followed untreated as part of the Diagnostic Innovations in Glaucoma Study (DIGS). Ocular hypertensive patients had elevated IOP in both eyes (>22 mmHg), normal visual fields on standard automated perimetry, and normal optic discs as evaluated by stereophotograph assessment. Glaucoma conversion was defined as development of reproducible visual field loss or progression of optic disc damage. Analyses included all IOP measurements from the baseline visit to time of progression (for converters) and last follow-up (for non-converters). Mean IOP was calculated as the arithmetic mean of IOP in all applicable visits, whereas IOP fluctuation was calculated as the standard deviation of IOP at these visits. Univariate and multivariate Cox regression analyses were used to evaluate the association between IOP fluctuation and time to progression. Multivariate models adjusted for age, central corneal thickness, vertical cup/disc ratio, and pattern standard deviation. For eye specific variables, the values from each eye were averaged to determine the predictive factor for each participant.
24 (23%) of 105 ocular hypertensive patients developed glaucoma during follow-up. Mean follow-up time was 84.7 ± 46.2 months. Mean (±SD) IOP fluctuation was 2.76 ± 1.16 mmHg in converters and 2.63 ± 0.86 mmHg in non converters (P = 0.548). IOP fluctuation was not a risk factor for conversion to glaucoma both in univariate (Hazard ratio [HR] = 1.19, 95% CI: 0.76 - 1.88; P = 0.461) as well as in multivariate analysis (adjusted HR = 1.42; 95% CI: 0.90 - 2.24; P = 0.130). Mean IOP during follow-up was a significant risk factor for progression both in univariate (HR = 1.12; 95% CI: 1.01 - 1.25; P = 0.041) as well as in multivariate analysis (adjusted HR = 1.16; 95% CI: 1.03 - 1.31; P = 0.013).
Long-term IOP fluctuations do not appear to be significantly associated with risk of developing glaucoma in untreated ocular hypertensive subjects.
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