Frequency domain optical coherence tomography of human Henle fiber layer

Abstract

Objective To observe the frequency domain optical coherence tomography (SD-OCT) features of Henle fiber layer (HFL) of health adults in china by changing the angle of the measurement beam.Methods Twenty-four subjects (28 eyes) who showed no abnormalities on routine eye examination were included in the study,including 15 males (16 eyes) and 9 females (12 eyes) with an average age of (35.51 ± 3.54) years old,and mean refraction power of (-0.89 ± 1.15) D.All subjects underwent corrected visual acuity,intraocular pressure,slit lamp microscope,direct ophthalmoscope,visual field and SD-OCT examination.The macular area was scanned by Zeiss Cirrus SD-OCT (5 HD line) single line scan mode.Based on the entry position of the SD-OCT beam through the pupil,the subjects were divided into 3 groups,including group A (center of the pupil),group B (near the temporal edge of the pupil) and group C (near the nasal edge of the pupil).The thickness of outer plexiform layer (OPL),HFL,and outer nuclear layer (ONL) were measured at 0.75 mm,1.50 mm from the fovea.Results When entry position of the SD-OCT beam was near the temporal edge of the pupil (group B); there were two layer structures with different signal intensities in the weak reflectivity zones in front of the external limiting membrane (ELM).The signal of the inner layer was slightly higher than the outer layer.The OPL thickness at the decreased side (nasal) increased significantly compared with the other side,but the ONL thickness was significantly thinner than other side.When entry position of the SD-OCT beam was near the nasal edge of the pupil (group C),there were also two layer structures with different signal intensities in the weak reflectivity zones in front of the ELM.The signal of the outer layer was slightly higher than the inner layer.The OPL thickness at the decreased side (temporal) increased significantly compared with the other side,but the ONL thickness was significantly thinner than other side.The OPL thickness at the decreased side was significantly different between these 3 groups (P＜0.01).Conclusions SD-OCT provided the possibility of distinguishing HFL from the actual ONL by changing the angle of the measurement beam.This finding has great clinical significance for related diseases affecting HFL or ONL. Key words: Photoreceptor cells; Tomography,optical coherence