Effect of Dry Eye Treatment on Corneal Astigmatism Measurements

This prospective single-center study evaluates the effect of dry eye disease and short-term ocular surface treatment on the agreement and repeatability of corneal astigmatism measurements in patients with age-related cataract. Participants undergoing preoperative cataract evaluation are classified into a control group or a dry eye disease group according to ocular surface symptoms and objective tear film findings. All participants undergo ocular surface assessment and repeated corneal measurements using three commonly used devices: IOLMaster 700, Pentacam AXL, and iTrace Prime. Measurements include keratometric corneal astigmatism, total corneal astigmatism, and vector components of astigmatism. Patients with dry eye disease receive 0.3% sodium hyaluronate eye drops four times daily for 2 weeks, after which ocular surface assessment and device measurements are repeated. The primary objective is to determine whether dry eye disease reduces interdevice agreement and test-retest repeatability of corneal astigmatism measurements, and whether short-term ocular surface treatment improves measurement stability. Interdevice agreement is assessed using Bland-Altman analysis, and repeatability is evaluated using within-subject standard deviation, test-retest repeatability, and intraclass correlation coefficient.

Inclusion Criteria: * Patients with age-related cataract undergoing preoperative ocular examination. * Ability to complete ocular surface evaluation, including the Ocular Surface * Disease Index questionnaire, non-invasive tear film break-up time, tear meniscus height, Schirmer test, and ocular surface staining. * Ability to complete repeated corneal astigmatism measurements using IOLMaster 700, Pentacam AXL, and iTrace Prime. * Ability to maintain stable fixation during device measurements. Provision of written informed consent. Exclusion Criteria: * Previous ocular surgery or ocular trauma. * Corneal degeneration, corneal dystrophy, or other corneal diseases that could affect corneal measurements. * Active corneal or conjunctival infection. * Uveitis. * Use of any topical eye drops within 24 hours before examination. * Use of antiglaucoma medications. * Contact lens wear within 1 month before examination. * Previous or ongoing treatment for dry eye disease. * Poor fixation during device measurements. * Poor-quality measurements from any study device