Specificity of the Program Threshold Noiseless Trend for Perimetric Progression Analysis

Abstract

Purpose: To evaluate the specificity of the Threshold Noiseless Trend program (TNT), designed to measure progression in visual fields, using four procedures.

Materials and Methods: A. In 63 eyes with ocular hypertension, whose last examination showed no perimetric or morphological defects, we performed a mean of 7.70 ± 1.71 follow-up examinations during 2.2 ± 0.6 years. B. In 81 glaucomatous eyes examined twice with a bracketing strategy (Octopus 1-2-3 perimeter), we calculated mean threshold value and long-term fluctuation. We simulated 12 different visual fields, adding a random component to simulate an equivalent fluctuation of amplitude. C. Seventy-two glaucomatous eyes, with and without progression, were examined 7.76 ± 1.25 times during 4.88 ± 1.39 years using the Humphrey-Sita Standard strategy. Visual field tests were randomly disordered and analyzed using TNT. D. 1221 eyes were examined 7.19 ± 3.5 times during 3.50 ± 1.45 years (10,407 visual fields) using TOP-G1 program. We detected progression in 204 eyes using TNT. They were re-evaluated after random disordering of visual field tests.

Results: The four procedures indicated specificity ≥ 95% as from the seventh examination; this reduced to 90% in experiment C with six examinations, and in experiments A and C with five examinations.

Conclusions: The specificity of TNT may be considered to be over 95% with a large number of examinations, and 90–100% with fewer examinations. At least five examinations are required for a basic interpretation of progression, and preferably more than six to guarantee the specificity of the result.

KEYWORDS::

• Glaucoma
• Perimetry
• Progression
• Specificity
• Visual field

ACKNOWLEDGMENT

This work was supported in part by Fondo de Investigación Sanitaria (FIS), Instituto Carlos III, Ministerio de Sanidad y Consumo, Spain and FEDER foundation.

Declaration of interest: The first-named author has a proprietary interest in the programs used for this paper. The other authors declare no conflict of interest. The authors alone are responsible for the content and writing of the paper.