THE COMPARISON OF TSNIT STANDARD DEVIATION VALUES IN GLAUCOMATOUS PATIENTS WITH MYOPIA AND MYOPIC PATIENTS MEASURED WITH GDx VCC

Introduction. The objective thickness measurement of retinal nerve fiber layer (RNFL) is now possible with scanning laser polarimetry (GDx VCC). The TSNIT (temporal-superior-nasal-inferior-temporal) parameters are: TSNIT Average, Superior Average, Inferior Average, TSNIT Standard Deviation, Inter-eye-Symmetry and nerve fiber indicator (NFI). TSNIT Standard Deviation captures the modulation (peak to trough difference) of the double-hump pattern. A normal eye will have high modulation in the double-hump RNFL pattern, while a glaucoma eye will typically have low modulation in the double-hump pattern. As a result, high modulation will have a high TSNIT Standard Deviation value while low modulation will have low TSNIT Standard Deviation value. Objective. Our research aim was to evaluate and to compare the TSNIT Average and TSNIT Standard Deviation in glaucomatous patients with myopiс refraction and patients with myopia. Materials and methods. We examined two matched patient groups: basic - myopic patients with open-angle glaucoma 79 subjects (112 eyes) and control group 21 patients with myopia (39 eyes). All patients underwent imaging with the scanning laser polarimeter with variable corneal compensation GDx VCC. GDx parameters were TSNIT Average and TSNIT Standard Deviation. The Kruskal-Wallis test, the Mann-Whitney U-test and Spearman's rank correlation coefficient was applies for comparing groups and assessing the correlation. P values of P < 0,05 were considered. Conclusion. We discover the statistically significant reduce of TSNIT Standard Deviation depending on the increase of myopia degree (P = 0,01) and the reducement of this measure depending on the stage of open-angle glaucoma but it was not significant (Р = 0,1). Our study determined the higher values of TSNIT Standard Deviation in myopia relative to the open-angle glaucoma patients with myopia. The difference was statistically significant (P < 0,05) in most cases except the comparison between myopic patients with open-angle glaucoma in stages I and II and high myopes (Р > 0,05). The study demonstrated also a significant negative correlation of myopia grade and TSNIT Standard Deviation (rs = -0,3; P = 0,002) and a significant inverse correlation between the open-angle glaucoma stage and TSNIT Standard Deviation (rs = - 0,3; P = 0,03).

лазерная поляриметрия, стандартное отклонение значений в расчетной окружности, слой нервных волокон сетчатки, глаукома, миопия

1. Курышева, Н. И. Роль методов визуализации диска зрительного нерва и слоя нервных волокон сетчатки в ранней диагностике глаукомы / Н. И. Курышева // Глаукома. - 2007. - № 1. - C. 16-21.

2. Remo, S. Jr. The Optic Nerve in Glaucoma / S. Jr. Remo. - Rio de Janeiro. «Cultura Medica», 2006. - 404 p.