SCIENTIFIC CORRESPONDENCE A new technique for tear film fluorophotometry

Aim: To develop a reliable and objective non-touch technique for determination of tear volume and tear secretion by means of tear film fluorophotometry. Methods: 10 defined concentrations of sodium fluorescein were given in an artificial chamber and measured by the Fluorotron Master (Coherent Radiation Inc). A calibration line was established and the calibration equation was programmed into the Fluorotron Master computer software. In 28 patients (56 eyes) with dry eye symptoms and 15 volunteers (30 eyes) tear volume and tear secretion were then measured directly without taking a tear sample, using the new technique. Results: The values obtained by the Fluorotron Master measuring 10 defined fluorescein concentrations within an artificial chamber are approximately 100 times lower than the actual concentrations. The calibration line led to a calibration equation: y = 36 + 0.01 × X. The mean tear secretion in 56 eyes of patients with dry eye symptoms was 2.48 μl/min, compared to 3.4 μl/min in healthy volunteers. The difference was statistically significant. Average tear volume was 7.0 μl in patients and 7.2 μl in healthy volunteers with no statistically significant difference. Conclusion: The method developed is a simple and reliable non-touch technique without the need for taking a tear sample, which makes the examination faster and more comfortable for the patient.