Changes in computerized videokeratography induced by artificial tears.

PURPOSE

To analyze the effect of several standard artificial tear preparations on computerized videokeratographic measurements.

SETTING

Cullen Eye Insitute, Baylor College of Medicine, Department of Ophthalmology, Houston, Texas, USA.

METHODS

We evaluated one eye each in 18 normal volunteers. Using the EyeSys Corneal Analysis System (EyeSys Technologies), we obtained corneal topographic measurements at baseline and 0.5, 1, 2, 3, 4, 5, 6, 8, and 10 minutes after instillation of the following preparations: balanced salt solution, Tears Naturale II, Tears Naturale Free, Cellufresh, Celluvisc, HypoTears, and HypoTears PF. We analyzed changes in curvature of the keratographic rings at radii 1 to 5 mm and changes in keratometric-equivalent astigmatic power and meridian.

RESULTS

All preparations except HypoTears and Tears Naturale II induced statistically significant, time-dependent changes in mean corneal power in the central 5 mm corneal zone compared with baseline measurements (P < .05). The relationship between change in dioptric power over time varied with preparation type and was nonlinear in nature. In all cases, the mean induced change was < or = 0.5 diopter. Except for Celluvisc, tear administration produced minimal changes in the values of corneal astigmatic power or meridian.

CONCLUSION

When performing serial measurements of mean corneal power, the greatest consistency was achieved with no tears or with instillation of HypoTears or Tears Naturale II.