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S. Mosaed, J.H. K. Liu, R.N. Weinreb; Comparison of 24–Hour Intraocular Pressure Profiles in Patients With Thinner vs. Thicker Central Corneal Thickness . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4859.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare the 24–hour intraocular pressure (IOP) profiles of eyes with thinner vs. thicker corneas in a group of healthy and glaucomatous patients. Methods: We reviewed the 24–hour data of IOP from the right eye collected from 32 glaucoma patients and 15 age–matched controls housed in a sleep laboratory. Central corneal thickness (CCT) was determined by taking the average of three consecutive ultrasound pachymetry measurements in the right eye of each subject. IOP was measured every two hours using a pneumatonometer in both the sitting and supine positions during the diurnal/wake period (7AM to 11 PM ), and in the supine position only during the nocturnal/sleep period (11 PM to 7 AM). The glaucoma patients and the age–matched controls were each further divided into two groups based on CCT, using 545 microns as the cutoff between the thicker and thinner groups. For the glaucoma patients, the mean CCT in the thicker cornea group was 585.8 (n=19), and in the thinner group was 503.1 (n=13). The mean of the thicker CCT vs. thinner CCT of the age–matched control group was 568.8 (n=9) and 523.7 (n=6), respectively. The mean, peak, and range 24–hour IOP of the thinner CCT patients were compared to those with thicker corneas in the glaucoma group or the control group using the two–tailed Student’s t–test. The analysis was then repeated after making theoretical adjustments for CCT on IOP according to the linear formula: Corrected IOP= measured IOP–(CCT–545)/50x2.5 mmHg. Results: The mean, peak, and range 24–hour IOP between the thicker and thinner cornea groups were not significantly different in either the glaucoma patients or the age–matched controls when using the uncorrected IOP data (p>0.05). The range of 24–hour IOP was also not significantly different in either group after correcting for CCT. In the glaucoma patients and the age–matched controls, the corrected mean and peak 24–hour IOP was significantly higher in the thinner cornea groups (p<0.05). Conclusions: The uncorrected 24–hour IOP profile of patients with thinner corneas is similar to that of patients with thicker corneas. However, after applying a correction factor to the IOP data, the mean and peak 24–hour IOP is significantly higher in the thinner cornea patients, irrespective of the diagnosis of glaucoma.
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