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.

Hypoplasia of the Internal Carotid Artery: Duplex Ultrasonographic Findings

No abstract available.

Glaucoma Progression Detection by Retinal Nerve Fiber Layer Measurement Using Scanning Laser Polarimetry: Event and Trend Analysis

PURPOSE: To evaluate the use of scanning laser polarimetry (SLP, GDx VCC) to measure the retinal nerve fiber layer (RNFL) thickness in order to evaluate the progression of glaucoma. METHODS: Test-retest measurement variability was determined in 47 glaucomatous eyes. One eye each from 152 glaucomatous patients with at least 4 years of follow-up was enrolled. Visual field (VF) loss progression was determined by both event analysis (EA, Humphrey guided progression analysis) and trend analysis (TA, linear regression analysis of the visual field index). SLP progression was defined as a reduction of RNFL exceeding the predetermined repeatability coefficient in three consecutive exams, as compared to the baseline measure (EA). The slope of RNFL thickness change over time was determined by linear regression analysis (TA). RESULTS: Twenty-two eyes (14.5%) progressed according to the VF EA, 16 (10.5%) by VF TA, 37 (24.3%) by SLP EA and 19 (12.5%) by SLP TA. Agreement between VF and SLP progression was poor in both EA and TA (VF EA vs. SLP EA, k = 0.110; VF TA vs. SLP TA, k = 0.129). The mean (+/-standard deviation) progression rate of RNFL thickness as measured by SLP TA did not significantly differ between VF EA progressors and non-progressors (-0.224 +/- 0.148 microm/yr vs. -0.218 +/- 0.151 microm/yr, p = 0.874). SLP TA and EA showed similar levels of sensitivity when VF progression was considered as the reference standard. CONCLUSIONS: RNFL thickness as measurement by SLP was shown to be capable of detecting glaucoma progression. Both EA and TA of SLP showed poor agreement with VF outcomes in detecting glaucoma progression.

Cerebral Air Embolism Associated with Pulmonary Tuberculosis

No abstract available.

Clinical Validation of Visual Field Index

PURPOSE: To determine the associations of visual field index (VFI) with advanced glaucoma intervention study (AGIS) score, mean deviation (MD), pattern standard deviation (PSD), and average retinal nerve fiber layer (RNFL) thickness as measured by optical coherence tomography (OCT) and to evaluate the diagnostic abilities of these parameters. METHODS: One hundred fifteen glaucomatous eyes and 78 healthy eyes were enrolled in this cross-sectional study. Each participant had a Humphrey visual field analyzer test and OCT done. The diagnostic abilities of these parameters were analyzed using the receiver operating characteristic (ROC) curve, and we sought to determine the association of these parameters with VFI by Pearson correlation analysis. RESULTS: The associations between analyzed parameters and VFI were statistically significant (all, p<0.001). The area under the ROC curve (AUROC) value of VFI was greater than that of the MD and AGIS score (all, p<0.001) but was not different from the PSD and RNFL average thickness measured by OCT (p=0.756, p=0.638). CONCLUSIONS: The VFI showed significant associations with AGIS score, MD, PSD, and average RNFL thickness as measured by OCT and revealed similar diagnostic abilities as these parameters.

The Clinical Manifestation of Unilateral Acute Hydrops after Bilateral Laser In Situ Keratomileusis (LASIK)

PURPOSE: To report a case of a patient who underwent penetrating keratoplasty due to acute hydrops six years after undergoing a bilateral LASIK procedure. METHODS: A 19-year old male patient with -2.75 diopter myopia received a bilateral LASIK operation at a local clinic. Forty-seven months later, -2.00 cyl axis 130o astigmatism was induced in his left eye and additional surgery was performed to correct the LASIK-induced astigmatism. The patient was referred to our hospital 16 months after the secondary operation due to reduced visual acuity in his left eye. He was diagnosed with keratectasia and acute hydrops, and penetrating keratoplasty was performed. RESULTS: The retrospective analysis of the corneal topography prior to the LASIK surgery revealed that the inferior minus superior(I-S) value was 1.25 in the right eye and 1.3 in the left eye. At the time of the first evaluation at out hospital, a slit lamp examination showed an approximate 8 x 7.5mm sized area filled with aqueous humor between the corneal flap and residual stroma, and Descemet's membrane rupture was observed. Furthermore, the histopathological section of the patient's cornea confirmed keratocytes with myxoid degeneration and edematous change. CONCLUSIONS: In young patient, particularly those with suspicious asymptomatic keratoconus, LASIK and further enhancement surgery afterwards should be considered and approached in a cautious and deliberate manner.

Conjunctival Mini-flap Technique and Conjunctival Autotransplantation in Pterygium Surgery

PURPOSE: To compare postoperative recurrence rates between conjunctival autotransplant ation and the conjunctival mini-flap technique in pterygium surgery and to identify factors associated with postoperative recurrence. METHODS: In a retrospective survey of patients who underwent pterygium surgery between March, 2001 and February, 2004 at Severance Hospital, 49 eyes with pterygium removed by the conjunctival mini-flap technique and 41 eyes that underwent pterygium removal surgery by the conjunctival autotransplantation technique were studied. RESULTS: During the mean follow-up period of 8.79 3.9 months, recurrence of pterygium was observed in 3 of 49 eyes (7.1%) that received the conjunctival mini-flap technique. There were 9 recurrent cases out of 41 eyes (21.9%) that were treated by the conjunctival autotransplantation technique. There was no statistical significance between recurrence rate and age, sex, or previous operation in either of the respective surgical techniques. CONCLUSIONS: This study showed that the conjunctival mini-flap technique has a lower recurrence rate than the conjunctival autotransplantation technique. We also found that the conjunctival mini-flap technique is an effective and safe technique that does not generally cause serious complications.