Abstract
Purpose: :
Analyzing the confocal profile of intensity using the retina module of HRT III is a diagnostic tool to localize the height of ILM and the RPE. This enables the measurement of the retinal thickness. Aim of this study was to determine the intra- and intersession reproducibility of this retinal thickness (RT) measurement in healthy eyes.
Methods: :
32 eyes of 32 healthy patients (mean age: 49 yrs; range: 21 to 67 yrs) underwent HRT III measurements of the macula. Absence of macular edema (ME) was shown with OCT and funduscopy. For all patients 5 HRT measurements were performed within 30 min (intrasession reproducibility (IntraSRP)). For intersession reproducibility (InterSRP) the same procedure was repeated at 2 consecutive days with 10 eyes of the patients above. The standard 9-zone-circle was centered in the foveola to analyze the images. Statistics (SPSS 12.0) including intraclass correlation coefficients (ICC) and paired t-test was performed.
Results: :
Mean RT [µm] were in r1centr: 263±50; r2temp: 310±48; r2sup: 314±46; r2nas: 296±49; r2inf: 311±47; r3temp: 331±45; r3sup: 337±42; r3nas: 320±44 and r3inf: 336±38.ICC intrasession in r1centr: 0.664; r2temp: 0.522; r2sup: 0.622; r2nas: 0.548; r2inf: 0.694; r3temp: 0.533; r3sup: 0.493; r3nas: 0.489 and r3inf: 0.561.ICC intersession were in r1centr: 0.880; r2temp: 0.883; r2sup: 0.569; r2nas: 0.861; r2inf: 0.779; r3temp: 0.775; r3sup: 0.943; r3nas: 0.827 and r3inf: 0.669.There was no statistically significant difference between the RT of day 1 and 2 (all p≥ 0.1) in all zones of the standard 9-zone-circle.
Conclusions: :
Mean macular thickness is central the smallest, increases in the outer circles and is superior and inferior higher than nasal and temporal. This is comparable to histological findings of other studies. We found a good coefficient of variation in the intrasession measurements of about 10% and a moderate to good intersession reproducibility. There is no consistency between the several ICC of intra- and intersession measurements. Further studies have to show the IntraSRP for patients with macular edema.
Keywords: imaging/image analysis: clinical • retina