Retinal Nerve Fiber Layer Measurement Variability with Spectral Domain Optical Coherence Tomography

PURPOSE: To evaluate the effect of the scanning laser ophthalmoscope (SLO) guided re-test mode on short- and long-term measurement variability of peripapillary retinal nerve fiber layer (RNFL) thickness obtained by spectral domain-SLO optical coherence tomography (SD-SLO/OCT). METHODS: Seventy five healthy eyes were scanned 3 times per day (intra-session variability) by both the SLO guided re-test mode and the independent mode of SD-SLO/OCT. Subjects were scanned 3 times by both modes at visits within a 2-week interval (inter-session variability). For testing longitudinal variability, 3 separate exams were performed over 6 months by both modes. The coefficient of variation (CV), reproducibility coefficient (RC) and intraclass correlation coefficient of RNFL thickness were compared between the two modes. RESULTS: The intra-session RC and CV ranged from 5.4 to 12.9 microns and 1.76% to 5.72% when measured by independent mode and 5.4 to 12.5 microns and 1.75% to 5.58% by re-test mode, respectively. The inter-session RC and CV ranged from 5.8 to 13.3 microns and 1.89% to 5.78% by independent mode and 5.8 to 12.7 microns and 1.90% to 5.54% by re-test mode, respectively. Intra-session and inter-session variability measurements were not significantly different between the two modes. The longitudinal RC and CV ranged from 8.5 to 19.2 microns and 2.79% to 7.08% by independent mode and 7.5 to 14.4 microns and 2.33% to 6.22% by re-test mode, respectively. Longitudinal measurement variability was significantly lower when measured by the re-test mode compared to the independent mode (average, p = 0.011). CONCLUSIONS: The SLO guided re-test mode for RNFL thickness measurement in SD-SLO/OCT employing a tracking system improved long-term reproducibility by reducing variability induced by inconsistent scan circle placement.

Clinical Results of Wavefront-guided LASIK

PURPOSE: To investigate and compare the clinical outcomes of wavefront-guided LASIK performed by 2 different laser platforms. METHODS: A retrospective analysis of consecutive cases of eyes that underwent wavefront-guided LASIK by using the VISX S4 CustomVue system and the Zyoptix Z100 system advanced personalized mode. All procedures were performed by one surgeon. Fifty-six eyes of 36 patients were included. Of the 56 eyes, 30 eyes underwent LASIK by using the VISX S4 CustomVue system (CustomVue group), and other 26 eyes underwent LASIK by using the Zyoptix Z100 system (APT group). Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, contrast sensitivity, total high order aberration (HOA), spherical aberration (SA) and Q-value were recorded preoperatively and at 1 week, 1 and 3 months postoperatively. RESULTS: There was no statistically significant difference between two groups in terms of preoperative UCVA, BCVA, manifest refraction, high order aberrations, Q-value and contrast sensitivity. Induced amount of SA was significantly lower in CustomVue group than in APT group (p = 0.02). CONCLUSIONS: Wavefront-guided LASIK performed by 2 different laser platforms caused clinically acceptable outcomes including good visual acuity and contrast sensitivity through 3 months. Furthermore, LASIK performed by VISX S4 CustomVue system caused less SA at three months after operation.

A Case of Prolonged Bilateral Inferior Altitudinal Visual Field Defect in a Young Migraineur

PURPOSE: To report a case of prolonged bilateral inferior altitudinal visual field defect in a young migraine patient. CASE SUMMARY: A 13-year-old female patient presented with bilateral disturbance of visual acuity and visual field, which had begun one month before. She complained of headache, with recently increasing frequency, that occurred 3 or 4 days a week for about 2~3 hours duration, sometimes accompanied by nausea and located in the frontotemporal and retrobulbar area. Brain magnetic resonance imaging showed no abnormal finding in the brain and orbit. Her visual acuity was hand motion in both eyes and Humphrey visual field test showed bilateral inferior altitudinal visual field defect. Pupillary resonse was normal and extraocular muscle movement, anterior segment and fundus were also normal in ophthalmologic examination. Her best corrected visual acuity was 1.0 in both eyes by fogging method, but bilateral inferior altitudinal visual field defect persisted for 6 months follow-up. CONCLUSIONS: Bilateral inferior altitudinal visual field defect can be developed in a migraine patient without other causes. Careful examinations to rule out other causes such as ischemic optic neuropathy or brain infarct should be performed in a migraine patient who complains of visual disturbance.

Glaucoma Diagnostic Performance of Macular and Retinal Nerve Fiber Layer by Spectral-Domain Optical Coherence Tomography

PURPOSE: To compare the performance of glaucoma diagnosis according to the macular and peripapillary retinal nerve fiber layer (RNFL) thicknesses, as determined by spectral domain optical coherence tomography (OCT). METHODS: Ninety-six normal, 63 early glaucoma and 37 moderate to advanced glaucomatous eyes were imaged by Cirrus OCT. The areas under the receiver operating characteristics curves (AUCs) of macular and RNFL thicknesses were calculated for discrimination of normal and glaucomatous eyes. The sensitivity and specificity of normative classification of each parameter were assessed. RESULTS: The glaucoma diagnostic capability determined by AUC was greater when based on the peripapillary RNFL than the macular thickness (0.914, 0.775, p<0.001). Both the early and the moderate-to-advanced group showed higher AUCs in peripapillary RNFL thickness (early glaucoma group; 0.870, 0.670, p<0.001, moderate to advanced glaucoma group; 0.990, 0.954, p=0.03). The inferior outer sector of macular thickness showed highest sensitivity among the parameters (58%). CONCLUSIONS: Although Cirrus OCT applied to determine macular thickness did not outperform that applied to determine peripapillary RNFL thickness in glaucoma diagnosis, applying Cirrus OCT to determine both thicknesses in diagnosis may help in understanding a patient's status.