Is single measurement enough to get a reliable result with optical coherence tomography?/Optik koherens tomografi ile guvenilir sonuc almak icin tek olcum yeterli mi?

Purpose: To evaluate the repeatability and reliability of retinal nerve fiber layer (RNFL) thickness measurements using optical coherence tomography (OCT). Material and Method: Two hundred sixty-six eyes of 135 subjects (glaucoma, glaucoma suspects and healthy) were included in this study. Three sequential inferior, superior, nasal and temporal RNFL thickness measurements were performed using Spectral OCT [Opko/OTI, Inc., Miami, FL] by one operator at one session without pupillary dilatation. The differences between these three measurements of each quadrant in each eye were compared in microns and percentages. Repeated measures analysis of variance was performed for statistical analysis. Reliability is measured by intraclass correlation coefficient (ICC) for each quadrant. Results: ICCs of all quadrants ranged between 0.77 and 0.92, with the measurements of nasal quadrant being the least reproducible and the inferior being the most reproducible of all quadrants. RNFL measurement errors over 20% were seen in 9.63% of nasal quadrant, 5.3% of temporal quadrant, 0.6% of superior quadrant and only 0.3% of inferior quadrant measurements. Discussion: In order to get more repeatable and reliable results with OCT, sequential measurements more than one should be considered. We believe that special attention is required in the analysis of data of nasal and temporal quadrants. (Turk J Ophthalmol 2012; 42: 11-5) Key Words: Glaucoma, optical coherence tomography, reliability, repeatability, retinal nerve fiber layer Ozet Amac: Optik koherens tomografi (OKT) ile retina sinir lifi tabakasi (RSLT) kalinligi olcumlerinin tekrarlanabilirligini ve guvenilirligini degerlendirmek. Gerec ve Yontem: Saglikli, glokom tanisi veya suphesi olan 135 kisinin 266 gozu calismaya katildi. Ayni seansta, ayni kisi tarafindan, pupil dilate edilmeden, OKT [Opko/OTI, Inc., Miami, FL] cihazi ile inferior, superior, nazal ve temporal RSLT kalinligi ardisik olarak 3 kez olculdu. Her gozun her kadraninin uc olcumu arasindaki farklar mikron ve yuzde cinsinden karsilastirildi. Istatistiksel analiz icin 'Tekrarli olcumlerde varyans analizi testi' kullanildi. Guvenilirlik 'Sinif ici korelasyon katsayisi'(SKK) ile degerlendirildi. Sonuclar: Tum kadranlarin SKK'si 0,72 ile 0,92 arasinda olup, nazal kadran olcumleri en az tekrarlanabilir, inferior kadran olcumleri ise tum kadranlar icinde en tekrarlanabilir olcumler olarak bulundu. Nazal kadran RSLT kalinligi olcumlerinin % 9,63'unde, temporal kadran olc