Effect of dry eye on Scheimpflug imaging of the cornea and elevation data

Objective: To evaluate the effect of dry eye on Scheimpflug imaging of the cornea and elevation data. Design: Prospective observational study. Participants: Scheimpflug images of 50 patients with dry eye who were being tested for eligibility for corneal refractive surgery were screened. Twelve eyes of 12 patients with abnormal Belin/Ambrosio enhanced ectasia display (BAD) anterior elevation difference were included in the study. The patients had no history of contact lens wear or any other sign of ectasia. Methods: Peak central corneal densitometry value, corneal volume, pachymetry at the thinnest point, and BAD anterior elevation difference value at the centre of the 9 mm zone were recorded before and after 4 weeks of dry eye treatment. Measurements were compared with the Wilcoxon signed rank test. Results: The mean corneal peak densitometry and volume were similar before and after therapy (p = 0.465 and p = 0.441, respectively). The mean anterior elevation difference value at the centre of the 9 mm zone before treatment (6.67 +/- 1.72 mu m) was significantly higher than the mean post-treatment value (4.00 +/- 1.48 mu m) (p = 0.002). The mean pachymetry at the thinnest location after treatment (548 +/- 11.0) was significantly higher than the pretreatment value (538 +/- 8.5) (p = 0.027). Conclusions: BAD anterior elevation differences and pachymetric measurements may be affected by ocular surface or tear film abnormalities associated with dry eye disease. Repeated evaluations after treatment may reveal normal results.