The Study of Retinal Nerve Fiber Layer Thickness of Normal Eyes Using Scanning Laser Polarimetry

Purpoe: To evaluate retinal nerve fiber layer (RNFL) thickness measurements in local normal Chinese subjects of different age groups and analyse the correlation of RNFL thickness with age using scanning laser polarimetry (SLP,GDxVCC). To assess the reproducibility of RNFL thickness measurement with GDxVCC. Methods: The RNFL thickness of 67 normal subjects (123 eyes) were measured by GDxVCC. The average TSNIT parameters were calculated. The differences of RNFL thickness between sex,right and left eyes,superior and inferior were compared. The relationship between RNFL thickness and age was analyzed with correlation analysis and linear regression analysis. The intraclass correlation coefficients (ICC) of three images in every eye were calculated. Results: The average peripapillary RNFL thickness at the superior,inferior and whole ellipse regions in 123 eyes of 67 normal subjects were (70.30±6.76)(?)m,(67.35±6.77)(?)m and (56.87±4.53)(?) m,respectively. The average TNSIT standard deviation was 23.68±4.61 and the average inter-eye symmetric value was 0.86±0.11. There were significant difference of RNFL thickness between superior and inferior (t=4.952,P < 0.001). There were significant difference of inferior RNFL thickness and TNSIT standard deviation between right and left eyes (P=0.005 and 0.002),while not significant difference of superior RNFL thickness and whole mean RNFL thickness between right and left eye (P=0.086 and 0.529). There was no significant difference in TSNIT parameters between different genders. There was a slight negative correlation average RNFL thickness in superior sector with age (decreased approximately 0.15 microns per year,P=0.047) in the subjects aged below 60 years old. The ICC values of RNFL thickness were >0.8 in superior,inferior and global. Conclusions: The RNFL thickness can be measured accurately by GDxVCC and the reproducibility of RNFL thickness measurement by GDxVCC is good. There was a slight negative correlation between average RNFL thickness in superior with age. More researches on the effects of age on RNFL thickness by GDxVCC are needed.

Retinal nerve fiber layer in primary open-angle glaucoma with high myopia determined by optical coherence tomography and scanning laser polarimetry

Background Fundus changes associated with high myopia （HM） may mask those associated with primary open-angle glaucoma （POAG）. This study aim to determine the characteristics of RNFL thickness changes in patients with both POAG and HM and compare these to changes in patients with only HM. The diagnostic capabilities of both OCT and GDxVCC in this subset of patients are also evaluated. Methods Twenty-two eyes with POAG and HM （spherical equivalent （SE） between -6.0 and -12.0 D） were evaluated, and 22 eyes with HM were used for comparison. Characteristic retinal nerve fiber layer （RNFL） thickness profiles in patients with POAG and HM were examined using optical coherence tomography （OCT） and scanning laser polarimetry with variable corneal compensation （GDxVCC）, and the diagnostic capabilities of these imaging modalities were compared. RNFL parameters evaluated included superior average （Savg-GDx）, inferior average （lavg-GDx）, temporal-superior-nasal- inferior-temporal （TSNIT） average, and nerve fiber indicator （NFI） on GDxVCC and superior average （Savg-OCT）, inferior average （lavg-OCT）, nasal average （Navg-OCT）, temporal average （Tavg-OCT）, and average thickness （AvgThick-OCT） on OCT （fast RNFL scan）. Visual field testing was performed and defects were evaluated using mean defect （MD） and pattern standard deviation （PSD）. Results The RNFL parameters （P 〈0.05） significantly different between groups included Savg-GDx, lavg-GDx, TSNIT average, NFI, Savg-OCT, lavg-OCT, Tavg-OCT, and AvgThick-OCT. Significant correlations existed between TSNIT average and AvgThick-OCT （r=0.778）, TSNIT average and MD （r=0.749）, AvgThick-OCT and MD （r=0.647）, TSNIT average and PSD （r=-0.756）, and AvgThick-OCT and PSD （r=-0.784）. The area under the receiver operating characteristic curve （AUROC） values of TSNIT average, Savg-GDx, lavg-GDx, NFI, Savg-OCT, lavg-OCT, Navg-OCT, Tavg-OCT, and AvgThick-OCT were 0.947, 0.962, 0.973, 0.994, 0.909, 0.917, 0.511, 0.906, and 0.913, respectively. The NFI AUROC was the highest value. Conclusions RNFL thickness was significantly lower in all but the nasal quadrant in patients with POAG and HM, compared to patients with only HM. Measurements with OCT and GDxVCC were well-correlated, and both modalities detected RNFL thickness chanaes. However. GDxVCC was better than OCT in detectina POAG in HM Datients.