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[The use of optical coherence tomography for identifying retinal nerve fiber layer progressive damage].

PURPOSE
To identify threshold values above which the intersession reduction of the retinal nerve fibers layer (RNFL) can be considered significant.


METHOD
In 79 eyes (41 patients) we have performed RNFL measurements with the Stratus OCT twice in the same session. The differences between these measurements were used to calculate the test-retest variability (on clock hours, quadrants and the average RNFL thickness) using the formula: Test-retest variability = 1.96 x standard deviation (95% confidence) The resulted "threshold values" were used to identify the possible progression in a study group of 119 eyes (61 patients), followed for an average of 2 years.


RESULTS
RNFL reduction exceeding the "threshold values" in 2 consecutive sessions was noticed in 18 eyes (15.12%). 12 eyes (10.08%) have fulfilled this criterion on 2 or more clock hours. 3 patients have had the criterion present on both eyes.


CONCLUSIONS
This appears to be a plausible method for identifying the progression of structural damage in glaucoma, deserving further researches for validation.