Retinal Nerve Fiber Layer Thickness in Children With Glaucoma

PURPOSE: To find the optimal parameter of retinal nerve fiber layer (RNFL) analysis in optical coherence tomography (OCT) for diagnosing glaucoma in children. METHODS: The study was comprised of 127 eyes of 84 patients (aged 6 to 18 years) who visited our institute between March 2006 and February 2008. Subjects were classified into normal, glaucoma suspect and glaucoma groups, and each eye was scanned using Stratus 3.0 OCT. Routine ophthalmic examinations including fundus examination, visual field test and OCT RNFL analysis were performed. RESULTS: There were 55 normal eyes, 27 glaucoma suspect eyes and 45 glaucomatous eyes. The average RNFL thickness was the most useful parameter to differentiate between the glaucoma and non-glaucoma groups. The next most useful parameter was inferior average thickness, followed by superior RNFL thickness. The sensitivity and specificity of the new discriminant of the formula used were 78%, and 68.6%, respectively. CONCLUSIONS: In OCT analysis, the average RNFL thickness is the most useful parameter in the diagnosis of glaucoma in children. The new discriminant of the formula is useful in the diagnosis of pediatric glaucoma patients.

Artifacts in Retinal Nerve Fiber Layer Analysis Using Optical Coherence Tomography

PURPOSE: To investigate the frequency and characteristics of artifacts which can cause errors in retinal nerve fiber layer nalysis using optical coherence tomography (OCT). METHODS: The frequency, characteristics and retinal lesions responsible for the artifact were analyzed for 179 patients (338 eyes) by OCT. All images were categorized into two groups according to the presence of artifacts and then, the differences between the two groups were analyzed by t-test and cross-tabulation analysis in terms of age, refractive error, peripapillary atrophic areas, and type of glaucoma. RESULTS: The male to female ratio was 1.37:1, average age was 47.6+/-15.7 years and average degree of refraction was -1.78+/-0.23 diopter. Artifacts were noted in 64 eyes (18.9%), and were present in the temporal quadrant in 12 eyes (18.8%), superior quadrant in 51 eyes (79.7%), nasal quadrant in 19 eyes (87.5%), and inferior quadrant in 8 eyes (48.4%). The average angle of the artifact was 138 degrees. Although retinal lesion, age, and glaucoma type were not significantly different between the two groups, peripapillary atrophy and myopia were significantly more common in the group with the artifact. CONCLUSIONS: When analyzing retinal nerve fiber layer by OCT, artifacts should be considered, especially in cases of peripapillary atrophy and myopia.

Influence of Lens Opacity on Nerve Fiber Layer Analysis in Glaucomatous and Normal Eyes

PURPOSE: To analyze the retinal nerve fiber layer in glaucoma eyes and in normal eyes, before and after cataract surgery using GDx (Laser Diagnostic Technologies, Inc., San Diego, CA, U.S.A), - a scanning laser polarimetry, and to evaluate the effect of lens opacity on retinal nerve fiber layer analysis. METHODS: Ocular examination and GDx analysis were performed one month before and after cataract surgery on 16 eyes of 10 patients affected with glaucoma and 14 normal eyes of 9 patients at St. Mary's Hospital. Regarding the eyes affected with glaucoma, only those who showed no evidence of glaucoma progression on a visual field examination before and after the cataract surgery were included, and every cataract surgery was performed perfectly. Comparisons of the GDx parameters before and after cataract surgery were performed using the Wincoxon signed rank test. RESULTS: All GDx parameters before and after cataract surgery in normal eyes showed no significant differences. In the glaucoma patients, differences in symmetry (p=0.047), superior ratio (p=0.007), ellipse modulation (p=0.001), and GDx number (p=0.008) were statistically significant. CONCLUSIONS: GDx is an examination based on the birefringent nature of retinal nerve fiber layer so the values can change according to changes in the cornea and lens, which are birefringent. This study compared the GDx parameters before and after cataract surgery of glaucoma patients and normal eyes. Our results showed that lens opacity has a minor and subtle effect on GDx parameters, and indicated the most sensitive parameters that reflect the change of retinal nerve fiber layer. Further studies should be performed using a larger sample with statistical support.