Optical Coherence Tomography Applied For Measurement Of Nerve Fiber Layer Thickness In Normal Eyes Of Chinese School Age Children And Teenagers

1 Purpose1. To quantitatively assess the normative reference values of peripapillary retinal nerve fiber layer (RNFL) in normal eyes of Chinese children and teenagers age 5 to 14 years old with optical coherence tomography (OCT).2. To investigate the relationship between retinal nerve fiber layer thickness and gender, right or left eye, and ages in Chinese subjects age 5 to 14 years old, and to analyze the characteristics of the variation of the RNFL parameters.2 Subjects and Methods2.1 Subjects180 eyes of 90 normal people age 5 to 14 years old presenting to the Ophthalmology Clinic at the Department of ophthalmology, Shanghai Jiao Tong University Affiliated First People's Hospital, from June in 2006 to January in 2007. The average age of those subjects is 9.94±2.26.2.2 Methods1. After being inquired of medical history and receiving the routine examination of ophthalmology, we choose the volunteers who met the standards of being examinedby OCT.2. The peripapillary RNFL of all participants was imaged on Stratus OCT^TM 3000. RNFL thickness around the disc was determined with 3.4 mm diameter circling scan, and it was measured and analyzed with the RNFL thickness average analysis program.Studied 24 parameters of RNFL thickness included 1-12 clock, the average thickness in the superior(S, Savg), nasal(N, Navg), inferior(I, Iavg) and temporal(T, Tavg) quadrant, the average thickness over all scanning test points(Avg.Thick), the maximum thickness in the superior (Smax) and inferior (Imax) quadrant, Smax/Imax, Smax/Tavg, Imax/Tavg, Smax/Navg, and the maximum thickness minus the minimum thickness(Max-Min).The results of the RNFL thickness parameters were recorded in clockwise order in right eyes and anticlockwise order in left eyes. The order is: superior (11-1 clock), nasal (2-4 clock), inferior (5-7 clock), temporal (8-10 clock).3. The data was analyzed with SPSS 13.0 commercial statistical software.3 Results1. The average RNFL thickness (μm) of the normal subjects age 5 to 14 years old in clock type (1-12) were 133.49±24.31, 87.37+17.57, 58.59±12.61, 74.43±17.10, 116.42±21.90,149.79±24.82,154.10±21.87, 87.82±18.73, 66.21±10.73, 97.19±18.39, 148.94±22.61 and 150.21±26.51, respectively. The average RNFL thickness (μm) of those in the superior (S), nasal (N), inferior (I) and temporal (T) quadrant were 144.40±17.33, 73.44±13.12, 139.52±16.81 and 84.53±15.44, respectively. Avg. Thick was 110.48±9.07 μm. The normative values of Smax, Imax, Smax/Imax, Smax/Tavg, Imax/Tavg, Smax/Navg and Max-Min were 176.59±22.90μm, 176.37±21.40μm, 1.01±0.16,2.15±0.40,2.14±0.36,2.48±0.58 and 137.54±23.85μm, respectively.2. According to different genders: Only five RNFL thickness parameters among 48 parameters (24 for left eye and 24 for right eye) had statistically significant differences (P<0.05).3. According to right or left eye: Thirteen RNFL thickness parameters(54.2%) in total twenty four parameters including 1, 2, 3, 10, 11, 12, S, N, Imax, Smax/Tavg, Imax/Tavg, Smax/Navg and Max-Min had statistically significant differences (P<0.05).4. According to different age groups: Nine RNFL thickness parameters(37.5%) in total twenty four parameters including 11 12 S Avg. Thick Smax Smax/Imax Smax/Tavg Smax/Navg and Max-Min had statistically significant differences (P<0.05), and the other 15 parameters did not have.5. The coefficient of variation (%) of the RNFL thickness parameters of clock type (1-12) were 18.21, 20.11, 21.52, 22.97,18.81,16.57,14.19, 21.32,16.21,18.92, 15.18 and 17.65, respectively. S, N, I, T and Avg were 11.20, 17.87, 12.05,18.27 and 8.21, respectively.4 Conclusions1. OCT can be effectively used to measure RNFL thickness in children and teenagers. This study can establish the normative data of RNFL thickness parameters of 5-14 years old Chinese people. And this may assist in identifying changes in RNFL thickness in Chinese children and teenagers, especially be applied to the diagnosis of glaucoma.2. The normative values of the RNFL thickness parameters in the normal people age 5 to 14 years old are available consequently. The RNFL thicknesses of the normal eyes are the thickest at 7,12, 6 and 11 o'clock (which are close to). In contrast, those at the 3 and 9 o'clock are the thinner. It is much thicker in the inferior and superior quadrant (which are close to) than temporal quadrant, and progressively less in nasal quadrant.3. Some RNFL thickness parameters have statistically significant differences in the following factors: different gender, right or left eyes, groups according to age.4. The variations of the RNFL thickness parameters are unequal. Among the all 24 parameters, CV of the Avg. Thick is the least. Among the 12 clocks, CV of 7 and 11o'clock are the least. In different quadrant, CV of S and I is much less than N and T, and CV of Smax/Navg is greater than others in the remaining parameters.5. To research and make use of the rules of RNFL thickness parameters in normal subjects deserve careful consideration. We should ponder early glaucoma or other diseases if the stable parameters are abnormal or only the liable factors of variability if the instable parameters change.