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May 23, 2005
Measuring CCT? Plan to Do It Again
Ophthalmology 2005; 112:225-228
Researchers at London’s Moorfields Eye Hospital recruited 51 patients from a glaucoma clinic and measured central corneal thickness using an ultrasonic handheld pachymeter by a trained observer three consecutive times over a three-month period. The readings showed clear fluctuation over the period, with a mean difference in CCT of 9.6 ±26.9 µm in the right eye and 19.0 ±29.2 µm in the left. In addition, there was a systematic bias towards increased CCT being recorded at the second reading in both eyes, reaching statistical significance in both the right eye (P=0.02) and the left (P=0.0003). The criteria used to categorize the risk of developing glaucoma in the OHTS were then applied to these results. On the basis of the second reading, 32 percent of eyes required recategorization in both the right and left eyes.They conclude that CCT measurements taken within a clinical setting by a trained observer may show significant variability. Failure to do more than one CCT reading may result in misclassification and, thus, an inaccurate assignment of risk.
Posted by mehdi khanlari at May 23, 2005 11:23 PM