Abstract
Abstract: :
Purpose:To determine the effects of central corneal thickness on long term visual field results. Methods:In this retrospective study, charts were reviewed to obtain data. Information collected included: age, gender, central corneal thickness, and initial and consecutive follow–up visual field results. Central corneal thickness was measured by ultrasound pachymetry, and visual field was measured by the Humphrey Visual Field Analyzer. Exclusion criteria included: false positives > 25%, false negatives > 25%, fixations losses > 25%, and glaucoma hemifield test results indicating abnormally high sensitivity. Variables analyzed from the visual field test included mean deviation, pattern standard deviation, and the glaucoma hemifield test. Results:A total of 336 eyes were evaluated. Patients with thinner corneas (lower central corneal thickness) presented initially with significantly greater mean deviation (p<0.05) and pattern standard deviation (p<0.05) values via the Humphrey Visual Field Analyzer, indicating an overall worse visual field. Similarly, the patients with a lower central corneal thickness also significantly more often initially presented with an abnormal glaucoma hemifield test (p<0.05). Additionally, although not statistically significant, patients with thinner corneas demonstrated a more rapid loss of vision compared to patients with thicker corneas. Conclusions:Patients with thinner corneas initially present with overall greater mean deviation, pattern standard deviation, and an abnormal glaucoma hemifield test. This is likely due to the artificially inaccurate low intraocular pressure measurement caused by a thinner cornea, leading to a delay in the diagnosis of glaucoma until the patient presents with diagnosis of visual field loss, at which time irreparable optic nerve damage has already occurred. When measuring intraocular pressure, it is imperative to take central corneal thickness into account to prevent long–term visual field loss.
Keywords: optic disc • visual fields • clinical (human) or epidemiologic studies: risk factor assessment