Superior Quadrant Retinal Nerve Fiber Layer Thickness Research Articles

Evaluation of Retinal Nerve Fiber Layer Thickness with Spectral Domain Oct in Primary Open Angle Glaucoma and Ocular Hypertension

Purpose: To compare Primary Open Angle Glaucoma (POAG), Ocular Hypertension (OHT) and control groups by using Visual Field (VF) and Spectral Domain Optical Coherence Tomography (SD-OCT) and to investigate correlations between VF global indices and Retinal Nerve Fiber Layer (RNFL) thickness measurements. Methods: Forty patients with POAG, 55 patients with OHT, and 40 normal subjects were included in the study. All subjects were evaluated by standard automated perimetry and Cirrus HD-OCT. Results: RNFL global average thickness, average thicknesses in four quadrants and at 1 o’clock, 4 o’clock, 5 o’clock, 6 o’clock, 7 o’clock, 10 o’clock, 11 o’clock and 12 o’clock areas in POAG patients were significantly decreased compared with the OHT and the control groups. RNFL thicknesses at 2 o’clock, 8 o’clock and 9 o’clock areas in the POAG group were significantly lower than control subjects. There were statistically significant and a negative correlation between PSD and RNFL global average thickness, RNFL thicknesses in temporal quadrant and at 1 o’clock and 2 o’clock areas in the POAG group. According to the areas under the ROC curve, the parameter which has the best diagnostic ability was found as RNFL thickness in the superior quadrant. The sensitivity and specificity of Cirrus HD-OCT for RNFL thickness in superior quadrant were found 77% and 87%. Conclusion: The correlations between MD, PSD and RNFL thickness parameters could represent the consistency of functional and structural tests. RNFL measurement with SD-OCT could provide important information for detection of early stages of glaucoma.

Ability of spectral domain optical coherence tomography peripapillary retinal nerve fiber layer thickness measurements to identify early glaucoma

Purpose:To evaluate the ability of spectral domain optical coherence tomography (OCT) peripapillary retinal nerve fiber layer thickness (RNFLT) parameters to distinguish normal eyes from those with early glaucoma in Asian Indian eyes.Design:Observational cross-sectional study.Materials and Methods:One hundred and seventy eight eyes (83 glaucoma patients and 95 age matched healthy subjects) of subjects more than 40 years of age were included in the study. All subjects underwent RNFLT measurement with spectral OCT/ scanning laser ophthalmoscope (SLO) after dilatation. Sensitivity, specificity and area under the receiving operating characteristic curve (AROC) were calculated for various OCT peripapillary RNFL parameters.Results:The mean RNFLT in healthy subjects and patients with early glaucoma were 105.7 ± 5.1 μm and 90.7 ± 7.5 μm, respectively. The largest AROC was found for 12 o’clock- hour (0.98), average (0.96) and superior quadrant RNFLT (0.9). When target specificity was set at ≥ 90% and ≥ 80%, the parameters with highest sensitivity were 12 o’clock -hour (91.6%), average RNFLT (85.3%) and 12 o’ clock- hour (96.8 %), average RNFLT (94.7%) respectively.Conclusion:Our study showed good ability of spectral OCT/ SLO to differentiate normal eyes from patients with early glaucoma and hence it may serve as an useful adjunct for early diagnosis of glaucoma.

Comparison of Peripapillary Retinal Nerve Fiber Layer Thickness Measured by Spectral vs. Time Domain Optical Coherence Tomography

Purpose: To compare the peripapillary retinal nerve fiber layer (RNFL) thickness measured by spectral and time domain optical coherence tomography (OCT).Patients and Methods: One hundred and eighty-eight subjects (normal tension glaucoma, n = 80; primary open angle glaucoma, n = 49; healthy controls, n = 59) were included in this study. Peripapillary RNFL thickness was measured by an Optic Disc Cube 200 × 200 scan of the spectral domain Cirrus HD OCT and by a Fast RNFL scan of the time domain Stratus OCT. They were compared using linear regression (R2), Bland-Altman plots, weighted Kappa (Kw) coefficients, and areas under the receiver operating characteristic curve (AROC).Results: Except for the inferior quadrant, RNFL thickness measurements by Cirrus HD OCT were thinner than Stratus OCT (all p < 0.001); for the inferior quadrant, this tendency was vice versa (p = 0.043). Average RNFL thicknesses of the two OCTs showed a good correlation (R2, 0.852) but not excellent agreement (mean of difference, 4.0 μm; +1.96 SD, 10.7 μm; -1.96 SD, -18.6 μm). Regarding the probability codes, only the average RNFL thickness had almost perfect agreement (Kw, 0.983). In addition, Cirrus HD OCT had the largest AROC for the superior quadrant (0.795), but Stratus OCT had the largest AROC for average RNFL thickness (0.764) (p = 0.281).Conclusions: Except for the inferior quadrant, the average and quadrants RNFL thickness measured by the Cirrus HD OCT were thinner than the Stratus OCT. Regarding discriminating power for glaucoma detection, the Cirrus HD OCT was better than the Stratus OCT for the superior and inferior quadrant RNFL thicknesses but not for the average RNFL thickness.

Acute Primary Angle Closure Attack Does Not Cause an Increased Cup-to-Disc Ratio

To determine if an increased cup-to-disc ratio (CDR) and retinal nerve fiber layer (RNFL) loss occur after acute primary angle closure (APAC). Prospective, observational case series. Twenty participants with unilateral APAC provided 20 affected eyes and 20 fellow eyes (controls) for analysis. After initial presentation, participants attended 3 further assessments over a 12-month period (visit 2, within 2 weeks; visit 3, 2-3 months; and visit 4, 6-12 months), in which they underwent the following investigations: Heidelberg Retinal Tomography (Heidelberg Engineering, Dossenheim, Germany), optical coherence tomography of the RNFL and macula, and automated perimetry. Cup-to-disc ratio, optic cup area, neuroretinal rim area, RNFL thickness, macular thickness, and volume. There was no change from visits 2 to 4 in CDR (0.46 ± 0.17 vs. 0.47 ± 0.20; P = 0.94), neuroretinal rim area (1.64 ± 0.55 vs. 1.64 ± 0.57; P = 0.96), or other optic nerve head parameters analyzed in eyes with APAC. The mean overall RNFL thickness decreased from 106.6 ± 17.9 μm to 92.9 ± 18.3 μm between visits 2 and 3 (P<0.01) in affected eyes. The superior quadrant RNFL thickness decreased from 134.8 ± 25.9 μm to 113 ± 25.7 μm (P<0.01), and the inferior quadrant RNFL thickness decreased from 139.1 ± 28.4 μm to 115.6 ± 24.9 μm (P<0.01). There was no significant change in macular thickness or volume. This study demonstrated that an increase in CDR does not occur after APAC that is treated promptly, although RNFL loss does occur.

Concordance of Retinal Nerve Fiber Layer Defects between Fellow Eyes of Glaucoma Patients Measured by Optical Coherence Tomography

To determine the pattern of agreement of retinal nerve fiber layer (RNFL) defects between fellow eyes of glaucoma patients measured with optical coherence tomography (OCT). Observational, cross-sectional study. Seventy-seven glaucoma patients (154 eyes) underwent OCT (Stratus) imaging with the fast RNFL thickness protocol in both eyes. RNFL thickness at each location (12 clock-hour sectors and 4 quadrants) was measured. Main outcome measures were correlations between fellow eyes for RNFL thickness and categorical classifications of RNFL thickness. Nonfellow pairs of eyes, matched randomly, were used as controls. Fellow eyes showed significant correlations of RNFL thickness in all sectors and quadrants. Categorical ranking also showed significant agreement between fellow eyes in sectors 1 (P < .01) and 7 (P < .03), and in the superior quadrant (P < .01), inferior quadrant (P < .04), and total RNFL thickness (P < .04). None of the paired eyes in the control analysis showed significant correlations. The measurement of RNFL thickness and its categorical classification with OCT identified symmetry between fellow eyes of glaucoma patients. Categorical agreement on defective locations was found mostly for the inferior and superior locations, which corresponds with the typical pattern of early glaucomatous damage. Glaucomatous RNFL damage in 1 eye is correlated with damage at corresponding locations of the fellow eye.

Combining Nerve Fiber Layer Parameters to Optimize Glaucoma Diagnosis with Optical Coherence Tomography

To identify the best combination of Stratus optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness parameters for the detection of glaucoma. Observational cross-sectional study. Eighty-nine age-matched normal and perimetric glaucoma participants enrolled in the Advanced Imaging for Glaucoma Study. The Zeiss Stratus OCT system was used to obtain the circumpapillary RNFL thickness in both eyes of each participant. Right and left eye clock-hour data are analyzed together, assuming mirror-image symmetry. The RNFL diagnostic parameters were combined using either or-logic or and-logic approaches. Area under the receiver operating characteristic curve (AROC), sensitivity, and specificity are used to evaluate diagnostic performance. Overall average RNFL thickness has the highest AROC value (0.89) of all single parameters evaluated, followed by the inferior and superior quadrants (0.88 and 0.86, respectively). The clock hours with the best AROC values are in the inferior and superior quadrants. The highest AROC (0.92) was achieved by the or-logic combination of overall, inferior, and superior quadrant RNFL thicknesses. The 3-parameter combination was significantly better than the overall average alone (P = 0.01). The addition of more quadrants or clock hours to the combination reduced diagnostic performance. The best stand-alone diagnostic strategy for Stratus OCT RNFL data is to classify an eye as glaucomatous if the overall, inferior quadrant, or superior quadrant RNFL thickness average is below normal.

Follow-up of Nonarteritic Anterior Ischemic Optic Neuropathy with Optical Coherence Tomography

To study the characteristics of nonarteritic anterior ischemic optic neuropathy (NAION) as measured with optical coherence tomography (OCT) at diagnosis and during the first year after the episode. Cohort study. Twenty-seven patients diagnosed with NAION in our center between April 1, 2004 and March 31, 2006. Patients diagnosed with NAION underwent at the time of diagnosis and 6 weeks and 3, 6, and 12 months after presentation a complete ophthalmologic evaluation, including determination of Snellen visual acuity (VA), visual fields (VFs) (standard automated perimetry, Swedish Interactive Threshold Algorithm strategy 24-2), and optic nerve head (ONH) scanning with StratusOCT. Characteristics of the ONH and their relationship with VA and VFs. Initial mean retinal nerve fiber layer (RNFL) thickness in the affected eye was 200.9 microm (standard deviation [SD], 52.3 microm); this represented a 96.4% increase relative to the fellow eye. Percentages of RNFL loss 3, 6, and 12 months after onset were 38.9%, 42.3%, and 43.9%, respectively. At the 6-month visit, RNFL percentage decreases for the superior, nasal, inferior, and temporal quadrants were 51.5%, 28.5%, 41.2%, and 38.2%, respectively. Reduction in the superior quadrant RNFL thickness was statistically higher. Using regression analysis, it was found that for every micrometer of mean RNFL thickness lost there was a 2-decibel decrease in VF mean deviation (MD) and that there was a 1-line drop in Snellen VA for every 1.6 microm lost. The mean ONH area was 2.6 mm2 (SD, 0.4) in the unaffected eye; there was no correlation with VA, VF MD, or RNFL thickness of the affected eye at the last follow-up visit. Optical coherence tomography can diagnose optic disc edema and monitor RNFL loss over time. It is most useful at onset and 6 months after NAION, when RNFL loss has reached a plateau and is correlated with visual function. Future studies that aim to determine if a drug or intervention is useful for treating NAION may include OCT assessment of the RNFL thickness, because it provides an objective outcome measure correlated with visual performance.

Factors Influencing Optic Disc and Retinal Nerve Fiber Layer Parameters Measured by Optical Coherence Tomography

Purpose: To determine the factors influence retinal nerve fiber layer (RNFL) and optic nerve head (ONH) parameters measured by Stratus optical coherence tomography (OCT). Methods: Topographic RNFL thickness and optic disc parameters of 129 healthy Korean subjects of aged 14 to 87 were measured using the fast retinal nerve fiber layer thickness and fast optic disk algorithms of Stratus OCT. One eye of each subject was randomly selected for statistical analysis. Using multiple linear regression, the effect of optic disc area, age, refractive error, and zone beta on each parameter was analyzed. Results: Large discs had large horizontal integrated rim width (HIRW), cup area, rim area, C/D area ratio, and vertical C/D ratio. The thickness of average, superior, inferior, and nasal quadrant RNFL increased significantly with an increase in optic disc area. Average and superior quadrant RNFL thickness, and HIRW decreased with age. Refractive error showed a correlation with the vertical integrated rim area, horizontal C/D ratio, and temporal quadrant RNFL thickness. Gender and zone beta had no statistically significant influence on ONH and RNFL parameters. Conclusions: This study shows that optic disc size affects most RNFL thickness and ONH parameters. Because of the relationships revealed in this study, optic disc area in addition to age should be considered when the Stratus OCT RNFL thickness and ONH parameters are interpreted.