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 µm) was significantly higher than the mean post-treatment value (4.00 ± 1.48 µm) (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.