Assessment of optic disc anatomy and nerve fiber layer thickness in ocular hypertensive subjects with normal short-wavelength automated perimetry

PURPOSE: To compare optic disc topography and nerve fiber layer thickness in ocular hypertensive eyes and normal subjects. DESIGN: Prospective, case-controlled study. PARTICIPANTS AND CONTROLS: One eye in each of 20 normal and 27 ocular hypertensive patients was enrolled. METHODS: Consecutive normal and ocular hypertensive patients were enrolled. Each patient underwent complete ophthalmic examination, achromatic automated perimetry, short-wavelength automated perimetry, confocal scanning laser ophthalmoscopy, confocal scanning laser polarimetry, and optical coherence tomography. The intraocular pressure was 21 mmHg or less for normal subjects and at least 25 mmHg on two separate occasions in ocular hypertensive eyes. Structural parameters were compared between the two groups. Eyes with evidence of glaucomatous optic neuropathy, achromatic visual field loss, or evidence of focal visual field injury during short-wavelength automated perimetry were excluded. MAIN OUTCOME MEASURES: Optic nerve head topography and nerve fiber layer thickness. RESULTS: The three imaging technologies could not detect differences in optic disc or nerve fiber layer anatomy between the two groups. Ocular hypertensive eyes had a greater corrected pattern standard deviation than normal eyes during short-wavelength automated perimetry (P = 0.04). CONCLUSIONS: Ocular hypertensive eyes with normal achromatic automated perimetry and short-wavelength automated perimetry could not be distinguished from normal subjects with confocal scanning laser ophthalmoscopy, confocal scanning laser polarimetry, and optical coherence tomography.     

Heidelberg retina tomography and optical coherence tomography in normal, ocular-hypertensive, and glaucomatous eyes.

PURPOSE: To evaluate optic disc and retinal nerve fiber layer (RNFL) appearance in normal, ocular-hypertensive, and glaucomatous eyes undergoing confocal scanning laser ophthalmoscopy and optical coherence tomography (OCT). DESIGN: Prospective, cross-sectional study. PARTICIPANTS: Seventy-eight eyes of 78 consecutive normal (n = 17), ocular-hypertensive (n = 23), and glaucomatous subjects (n = 38) were enrolled. METHODS: Each patient underwent complete ophthalmic examination, achromatic automated perimetry, confocal scanning laser ophthalmoscopy (Heidelberg Retinal Tomography [HRT]), and OCT. Topographic HRT parameters (disc area, cup-disc ratio, rim area, rim volume, cup shape measure, mean RNFL thickness, and cross-sectional area) and mean OCT-generated RNFL thickness were evaluated in each group. MAIN OUTCOME MEASURES: OCT and HRT assessment of optic disc and RNFL anatomy. RESULTS: OCT RNFL thickness showed no difference between normal and ocular-hypertensive eyes (P = 0.15) but was significantly less in glaucomatous eyes (P < 0.001). HRT measurements of rim area, cup-disc ratio, cup shape measure, RNFL thickness, and RNFL cross-sectional area were significantly less in glaucomatous eyes (all P < 0.005) and were correlated with mean OCT RNFL thickness (all P < 0.02). RNFL thickness using OCT or HRT was highly correlated with visual field mean defect during achromatic perimetry (P < 0.0001). CONCLUSION: Both HRT and OCT can differentiate glaucomatous from nonglaucomatous eyes. RNFL thickness measurements using OCT correspond to disc topographic parameters using HRT.     

正常眼压性青光眼与高眼压性青光眼视神经图像分析的对比研究

目的 探讨正常眼压性青光眼 (normal-tension glaucoma, NTG)与高眼压性青光眼(high-tension glaucoma, HTG)视盘和视神经纤维层(retinal nerve fiber layer, RNFL)损害的差异。 方法 选择具有青光眼性视神经损害或RNFL缺损、相应的视野缺损的青光眼患者,NTG至少2次24 h眼压曲线和多次眼压测量均≤21 mm Hg(1 mm Hg =0.133 kPa)，HTG的眼压至少2次测量≥25 mm Hg。患者进行详细的眼科检查，同时用扫描激光偏振仪(scanning laser polarimetry, SLP)、光学相干断层扫描（optical coherence tomography, OCT）和海德堡视网膜成像仪(Heidelberg retinal tomography, HRT)定量测定视盘形态和RNFL厚度。比较两组视盘总体和相同象限测量参数。 结果 30例 NTG和 19例 HTG (共49只眼)患者的平均年龄分别为(59.6±8.6)岁(39～71岁)和(59.2±12.3)岁(36～75岁)。两组间视野缺损的平均偏差(mean deviation, MD)差异不显著(P＞0.05)。HRT测量的视盘 C/D面积比，除鼻侧象限外,NTG者视盘总体和上、下、颞侧3个象限均显著大于HTG者(P＜0.05 ),而盘缘面积小于HTG者(P＜0.05)；两组间其他视盘参数差异不显著。3种激光扫描技术所测定的总体和象限RNFL厚度，两组间差异不显著。 结论 NTG趋向大 C/D面积比和窄盘缘面积。RNFL缺损的形态分布须更精细和节段性分析。 (中华眼底病杂志, 2002, 18: 109-112)     

Quantitative assessment of atypical birefringence images using scanning laser polarimetry with variable corneal compensation

PURPOSE: To define the clinical characteristics of atypical birefringence images and to describe a quantitative method for their identification. DESIGN: Prospective, comparative, clinical observational study. METHODS: Normal and glaucomatous eyes underwent complete examination, standard automated perimetry, scanning laser polarimetry with variable corneal compensation (GDx-VCC), and optical coherence tomography (OCT) of the macula, peripapillary retinal nerve fiber layer (RNFL), and optic disk. Eyes were classified into two groups: normal birefringence pattern (NBP) and atypical birefringence pattern (ABP). Clinical, functional, and structural characteristics were assessed separately. A multiple logistic regression model was used to predict eyes with ABP on the basis of a quantitative scan score generated by a support vector machine (SVM) with GDx-VCC. RESULTS: Sixty-five eyes of 65 patients were enrolled. ABP images were observed in 5 of 20 (25%) normal eyes and 23 of 45 (51%) glaucomatous eyes. Compared with eyes with NBP, glaucomatous eyes with ABP demonstrated significantly lower SVM scores (P < .0001, < 0.0001, 0.008, 0.03, and 0.03, respectively) and greater temporal, mean, inferior, and nasal RNFL thickness using GDx-VCC; and a weaker correlation with OCT generated RNFL thickness (R(2) = .75 vs .27). ABP images were significantly correlated with older age (R(2) = .16, P = .001). The SVM score was the only significant (P < .0001) predictor of ABP images and provided high discriminating power between eyes with NBP and ABP (area under the receiver operator characteristic curve = 0.98). CONCLUSIONS: ABP images exist in a subset of normal and glaucomatous eyes, are associated with older patient age, and produce an artifactual increase in RNFL thickness using GDx-VCC. The SVM score is highly predictive of ABP images.     

Visual field defects and retinal nerve fiber layer defects in eyes with buried optic nerve drusen

PURPOSE: To evaluate the visual field with the use of automated perimetry and to evaluate the retinal nerve fiber layer (RNFL) with optical coherence tomography (OCT) in patients with buried optic nerve drusen (OND). DESIGN: Observational case control study. METHODS: Eyes with buried OND were defined as eyes with ultrasound-proved drusen that were not visible with indirect slit-lamp biomicroscopy. All eyes underwent automated perimetry. Some eyes underwent OCT to evaluate the RNFL. RESULTS: Fifty-eight eyes of 41 patients with buried OND were evaluated. Three eyes (5%) had inferior arcuate scotomas. The other 55 eyes did not have visual field defects. Twenty-one of the eyes without visual field defects underwent RNFL analysis with OCT. All 21 eyes had normal average RNFL thickness. Some eyes had focal RNFL defects, but it is not clear whether these defects were clinically significant. CONCLUSION: Visual field defects are uncommon in eyes with buried OND. Eyes with buried OND may have focal RNFL defects but have normal average RNFL thickness. In patients with buried OND and a visual field defect, consideration should be given to searching for other causes of the defect, especially if the defect is substantial.     

Can frequency-doubling technology and short-wavelength automated perimetries detect visual field defects before standard automated perimetry in patients with preperimetric glaucoma?

PURPOSE: To assess the ability of frequency-doubling technology (FDT) perimetry and short-wavelength automated perimetry (SWAP) to detect glaucomatous damage in preperimetric glaucoma subjects. PARTICIPANTS: Two hundred seventy-eight eyes of 278 subjects categorized as normal eyes [n=98; intraocular pressure <20 mm Hg, normal optic disc appearance, and standard automated perimetry (SAP)]; preperimetric glaucoma eyes (n=109; normal SAP and retinal nerve fiber layer defects or localized optic disc notching and thinning); and glaucoma patients (n=71; intraocular pressure >21 mm Hg, optic disc compatible with glaucoma, and abnormal SAP). METHODS: The preperimetric glaucoma group underwent at least 2 reliable full-threshold 24-2 Humphrey SAPs, full-threshold C-20 FDT, full-threshold 24-2 SWAP, optic disc topography using the Heidelberg Retina Tomograph II, laser polarimetry using the GDx VCC, and Optical Coherence Tomography (Zeiss Stratus OCT 3000). Receiver operating characteristic curves were plotted for the main Heidelberg Retina Tomograph, Optical Coherence Tomography, and GDx VCC parameters for the normal and glaucoma patients. The area under the receiver operating characteristic curve was used to determine the parameters indicating glaucomatous damage in the optic disc or retinal nerve fiber layer, which were used to establish additional subgroups of patients with preperimetric glaucoma. FDT and SWAP sensitivities were calculated for the patient subsets with structural damage and normal SAP. RESULTS: At least 20% of the patients with preperimetric glaucoma demonstrated functional losses in FDT and SWAP. The more severe the structural damage, the greater the sensitivity for detecting glaucomatous visual field losses. CONCLUSIONS: FDT and SWAP detect functional losses in cases of suspected glaucoma before glaucomatous losses detected by SAP.     

Comparison of optic disk and retinal nerve fiber layer thickness in nonglaucomatous and glaucomatous patients with high myopia

PURPOSE: To assess the optic nerve head (ONH) by optical coherence tomography (OCT), confocal scanning laser ophthalmoscopy (CSLO), and the retinal nerve fiber layer (RNFL) by OCT and scanning laser polarimetry (GDx) in highly myopic subjects. DESIGN: Observational cross-sectional study. METHODS: Thirty-five eyes of highly myopic individuals without glaucoma and 17 eyes of highly myopic patients with glaucoma were included in this study. All patients had myopia higher than 5.0 diopters and ocular axial length higher than 25 mm. In those patients without glaucoma, the intraocular pressure (IOP) was less than 21 mm Hg. RESULTS: Mean (SD) OCT cup-to-disk area ratio was 0.45 (0.30) and 0.58 (0.29) in the nonglaucomatous and glaucomatous subjects, respectively (P = .22); CSLO cup-to-disk area ratio was 0.27 (0.27) and 0.24 (0.23), respectively (P = .75); and OCT-RNFL was 65.2 (26.2) microm and 56.8 (28.6) microm (P = .43). CONCLUSIONS: OCT, CSLO, and GDx are not useful to discriminate nonglaucomatous and glaucomatous subjects that have high myopia.     

Retinal nerve fiber analysis and tomography of the optic disc in eyes with tilted disc syndrome.

BACKGROUND AND OBJECTIVE: To investigate retinal nerve fiber layer thickness and optic disc parameters in eyes with tilted disc syndrome. PATIENTS AND METHODS: Thirty-eight eyes with tilted disc syndrome (20 myopic control eyes, and 20 emmetropic control eyes) were examined. After a routine ophthalmologic examination of all eyes, scanning laser polarimetry (for retinal nerve fiber layer thickness) and scanning laser tomography (for optic disc parameters) were performed. Scanning laser polarimetry and scanning laser tomography parameters were compared in the different groups. RESULTS: On scanning laser polarimetry evaluation, statistically significant differences were found in the superior integral, nasal integral, and superior nasal quadrants of eyes with tilted disc syndrome compared with control groups (P = .01, P = .04, P = .00, P = .00, P = .00, and P = .00, respectively). On scanning laser tomography evaluation, statistically significant differences were found in average diameter, total contour area, effective area, average depth, volume above, neuroretinal rim area, and cup-disc ratio in eyes with tilted disc syndrome compared with control groups (P = .00, P = .00, P = .00, P = .04, P = .02, P = .00, and P = .01, respectively). CONCLUSION: Parameters acquired through imaging with scanning laser polarimetry and scanning laser tomography in eyes with tilted disc syndrome are different from those of normal eyes.     

Scanning laser polarimetry – a review

Glaucoma is a leading cause of irreversible blindness worldwide. Retinal ganglion cells and their axons represent the selective target of the disease. When visual function is still intact on standard automated perimetry and optic disc appearance is suspicious, an early diagnosis may be supported by the identification of a retinal nerve fibre layer (RNFL) defect in the peripapillary area. At present days, computer-based, real-time imaging of the peripapillary RNFL is available through instruments of easy use and with high levels of accuracy and reproducibility. Scanning laser polarimetry is performed by a confocal scanning laser ophthalmoscope with an integrated polarimeter (GDx-VCC). There is a considerable amount of scientific evidence about the role of this imaging technique for glaucoma diagnosis. The aim of this review is to describe the principles of operation, the examination procedure, the clinical role, the results of main diagnostic studies and the future development of the software for the scanning laser polarimetry.     

Quantitative analysis of axonal loss in band atrophy of the optic nerve using scanning laser polarimetry

AIMS: To measure axonal loss in patients with band atrophy from optic chiasm compression using scanning laser polarimetry (GDx, Laser Diagnostic Technologies, Inc, San Diego, CA, USA) and to evaluate the ability of this instrument to identify this pattern of retinal nerve fibre layer (RNFL) loss. METHODS: 19 eyes from 17 consecutive patients with band atrophy of the optic nerve and permanent temporal hemianopia due to chiasmal compression, and 19 eyes from an age and sex matched control group of 17 healthy individuals were prospectively studied. All patients were submitted to an ophthalmic examination including Goldmann perimetry and evaluation of the RNFL using scanning laser polarimetry. Mean RNFL thickness around the optic disc were compared between the two groups. The diagnostic performance of the deviation from normal analysis provided by the GDx software was also assessed. RESULTS: The peripapillary RNFL thickness (mean (SD)) of eyes with band atrophy was 47.9 (7.63) micro m, 37.1 (8.48) micro m, 57.0 (9.31) micro m, and 37.2 (8.86) micro m in the superior, temporal, inferior, and nasal regions, respectively. The total average was 43.7 (12.0) micro m. In the control group, the corresponding values were 71.1 (12.2) micro m, 40.4 (10.9) micro m, 85.4 (14.0) micro m, and 49.8 (10.1) micro m. The total average measured 67.9 (11.2) micro m. The measurements from eyes with optic atrophy were significantly different from those in the control group in all regions but the temporal. The deviation from normal analysis provided by the GDx software failed to identify the majority of abnormalities in the temporal and nasal regions of patients with band atrophy. CONCLUSIONS: Scanning laser polarimetry was able to identify axonal loss in the superior, inferior, and nasal regions, but failed to detect it in the temporal region of the optic disc, despite the fact that this area was clearly altered in eyes with band atrophy. This examination also showed poor sensitivity to detect axonal loss in the nasal region when GDx software analysis was used. The results of this study emphasise that RNFL evaluation using scanning laser polarimetry should be interpreted with caution in the study of eye diseases that lead to axonal loss predominantly in the nasal and temporal areas of the optic disc.     

Assessment of retinal nerve fiber layer using optical coherence tomography and scanning laser polarimetry in progressive glaucomatous optic neuropathy

PURPOSE: To describe a case of progressive glaucomatous optic neuropathy using scanning laser polarimetry with fixed (SLP-FCC) and variable corneal compensation (SLP-VCC) and optical coherence tomography (OCT). DESIGN: Observational case report. METHODS: A 21-year-old male with juvenile primary open-angle glaucoma developed progression because of noncompliance with therapy. The patient underwent dilated stereoscopic examination and photography of the optic disk, standard automated perimetry (SAP), OCT, and SLP imaging with FCC and VCC at the baseline examination and after four years of follow-up. RESULTS: Optic disk, retinal nerve fiber layer (RNFL) atrophy, and SAP progression was observed. Reduction in mean RNFL thickness (average, superior, inferior) was 18, 18, and 27 microns (OCT); 22, 40, and 17 microns (SLP-FCC); and 6, 12, and 12 microns (SLP-VCC), respectively. CONCLUSIONS: This case demonstrates that digital imaging of the peripapillary RNFL is capable of documentation and measurement of progressive glaucomatous RNFL atrophy.     

Scanning laser polarimetry with enhanced corneal compensation and optical coherence tomography in normal and glaucomatous eyes

PURPOSE: To examine the association between scanning laser polarimetry (SLP), using enhanced (ECC) and variable corneal compensation (VCC) with optical coherence tomography (OCT), and to compare their discriminating ability in the diagnosis of glaucoma. METHODS: Normal and glaucomatous eyes enrolled from four clinical sites underwent complete examination, automated perimetry, SLP-ECC, SLP-VCC, and OCT. Eyes were characterized in two groups based on the typical scan score (TSS): Normal birefringence pattern (NBP) was defined as a TSS of 80 to 100 and abnormal birefringence pattern (ABP) as TSS 相似文献   

Scanning laser polarimetry versus frequency-doubling perimetry and conventional threshold perimetry: changes during a 12-month follow-up in preperimetric glaucoma. A pilot study.

PURPOSE: To evaluate the possibility for detecting the progression in preperimetric primary open angle glaucoma (POAG) using scanning laser polarimetry (SLP), frequency-doubling technology (FDT), and conventional automated perimetry (AP). PATIENTS AND METHODS: 22 eyes of 11 preperimetric POAG patients were evaluated using SLP (Nerve Fiber Analyzer, GDx), AP (Humphrey 24-2 threshold test) and FDT (30 degrees threshold test). All eyes had intraocular pressure (IOP) higher than 21 mmHg before treatment, but were consistently lower than 22 mm Hg with unchanged topical medication before and during the study. At the initial evaluation session optic nerve heads showed mild glaucomatous changes but the visual fields were normal (MD better than 2.0 dB, Glaucoma Hemifield Test: within normal limits or borderline). AP and FDT measurements were repeated 6 months later, and all three tests were repeated 12 months after the first investigation. RESULTS: IOP, AP and FDT measurements showed no statistically significant changes during the 12-month follow up period. In contrast to this, a tendency for a glaucomatous type decrease was seen with SLP in the retinal nerve fibre layer (RNFL) thickness parameters (mean superior and inferior sector thickness values, ellipse average thickness and maximal modulation). The mean decrease of RNFL thickness in the superior and inferior sectors was 2.77 microm and 2.48 microm, respectively. Using the two-way nested ANOVA, which considers the relation between the right and left eyes of the subjects, the decrease was statistically significant (p=0.021) for the inferior sector RNFL thickness. CONCLUSION: The results suggest that scanning laser polarimetry is a useful technique to detect and measure glaucomatous progression in early glaucoma. Scanning laser polarimetry of the RNFL may help to detect and quantify early progression even if worsening is not seen with perimetry and FDT tests.     

Relation of optic disc topography and age to thickness of retinal nerve fibre layer as measured using scanning laser polarimetry, in normal subjects

AIMS: To evaluate the relation of the optic nerve head topographic measurements and age with the thickness of the retinal nerve fibre layer (RNFL) in normal Caucasoid subjects by means of scanning laser polarimetry and tomography. METHODS: Topographic optic disc measurements and RNFL thickness values of 38 normal Caucasoid subjects of both sexes aged 20 to 78 were measured using a confocal scanning laser ophthalmoscope and a confocal scanning laser polarimeter. One eye was randomly selected for statistical analysis. The effects of optic disc size, age, and optic disc head topographic measurements of total and regional RNFL thickness were evaluated. RESULTS: Age showed a significant correlation with the integral of the total RNFL thickness (R=-0.341, p<0.05). The optic disc size showed a significant correlation with the integral of the total, superior, and inferior quadrant RNFL thickness (R=0.425, p<0.01), (R=0.361, p<0.05), (R=0.468, p<0.05). Neuroretinal rim area (NRA) had a correlation with the superior and inferior quadrant RNFL thickness values (R=0.339, p<0.05) (R=0.393, p<0.05). There was no significant correlation between the other optic disc topographic measurements and RNFL thickness values (p>0.05). CONCLUSION: The thickness of total as well as superior and inferior quadrant peripapillary RNFL as measured by scanning laser polarimetry increased significantly with an increase in optic disc size. The cross sectional area occupied by superior and inferior polar RNFL increased significantly with an increase in NRA. The total cross sectional area occupied by RNFL decreased significantly with an increase in age. The effects of optic disc size, age, and NRA should be considered when the peripapillary RNFL thickness is evaluated.     

Comparison between GDx VCC scanning laser polarimetry and Stratus OCT optical coherence tomography in the diagnosis of chronic glaucoma

PURPOSE: To compare the abilities of scanning laser polarimetry with the variable corneal compensator (GDx VCC) with those of optical coherence tomography (Stratus OCT) in discriminating between healthy and early-to-moderate perimetric glaucomatous eyes. METHODS: A total of 95 glaucomatous patients (mean deviation - 3.7 +/- 3.0 dB, pattern standard deviation 4.5 +/- 2.7 dB) and 62 control subjects underwent imaging by the GDx VCC and Stratus OCT using both optic nerve head (ONH) and retinal nerve fibre layer (RNFL) scan protocols. One eye per patient was considered. Sensitivity at > or = 90% specificity and area under the receiver operating characteristic curve (AROC) were calculated for each GDx VCC and Stratus OCT index. RESULTS: The largest AROCs with Stratus OCT were associated with cup : disc area ratio (0.88) for ONH scan indices, and with average thickness (0.84) for RNFL scan indices. The nerve fibre indicator provided the greatest AROC for the GDx VCC indices (0.85). CONCLUSIONS: Both the GDx VCC and Stratus OCT instruments were shown to be useful in the detection of glaucomatous damage. The best performing indices for the GDx VCC and Stratus OCT with both ONH and RNFL scans gave similar AROCs, showing a moderate sensitivity in early-to-moderate glaucoma patients.     

Retinotopic organization of primary visual cortex in glaucoma: a method for comparing cortical function with damage to the optic disk

PURPOSE: To demonstrate that the relationship between the functional organization of primary visual cortex (V1) and damage to the optic disc in humans with primary open-angle glaucoma (POAG) can be measured using a novel method for projecting scotomas onto the flattened cortical representation. METHODS: Six subjects participated in this functional magnetic resonance imaging (fMRI) experiment. Structural damage to the optic disc and the retinal nerve fiber layer (RNFL) was measured by three techniques: scanning laser polarimetry (GDx ECC; Carl Zeiss Meditec, Dublin, CA), confocal scanning laser ophthalmoscopy (HRT II; Heidelberg Engineering, Heidelberg, Germany), and optical coherence tomography (StratusOCT; Carl Zeiss Meditec, Inc.). Cortical activity for viewing through the glaucomatous versus fellow eye was compared by alternately presenting each eye with a contrast-reversing checkerboard pattern. The resultant fMRI response was compared to interocular differences in RNFL or mean height contour for analogous regions of the visual field. RESULTS: fMRI responses to visual stimulation were related to differences in RNFL thickness or mean height contour between eyes. The correlation between fMRI responses and measurements of optic disc damage for OCT (RNFL), HRT (mean height contour), and GDx (RNFL) were r = 0.90 (P = 0.02), r = 0.84 (P = 0.04), and r = 0.79 (P = 0.063), respectively. The probability of observing all three correlations by chance was low (P = 0.0003). CONCLUSIONS: Cortical activity in human V1 was altered in these six POAG subjects in a manner consistent with damage to the optic disc. fMRI is a possible means for quantifying cortical neurodegeneration in POAG.     

Polarimetric nerve fiber analysis in patients with peripapillary myelinated retinal nerve fibers.

PURPOSE: The aim of this study was to compare the RNFL thickness in eyes with myelinated retinal nerve fibers (MRNF) and age, sex-matched controls using scanning laser polarimetry. METHODS: Seventeen patients with MRNF underwent a comprehensive ophthalmological examination including automated visual field testing, and scanning laser polarimetry with Nerve Fiber Analyser (NFA II). Twenty eyes with MRNF from 17 patients were available for the study. Sixteen healthy, age and sex-matched subjects were taken as controls. Retinal nerve fiber thickness measurements of the four sectors (superior, inferior, nasal, temporal) and along the whole circumference of the optic disc were obtained for affected and control eyes, and compared. RESULTS: Inferior average and inferior integral parameters of the NFA revealed significantly thinner RNFL thickness measurements in eyes with inferiorly located MRNF compared to controls. CONCLUSION: Retinal myelination alters the birefringent property of the RNFL, and results in diminished thickness measurements. Hence, NFA measurements in patients with MRNF may not be reliable.     

Comparative evaluation of optical coherence tomography in glaucomatous, ocular hypertensive and normal eyes

BACKGROUND: To correlate the findings of optical coherence tomography (OCT) evaluation of retinal nerve fiber layer (RNFL) thickness with visual field changes in glaucomatous, ocular hypertensive and normal eyes. MATERIALS AND METHODS: Thirty consecutive normal, 30 consecutive ocular hypertensive and 30 consecutive glaucomatous eyes underwent a complete ophthalmic examination, including applanation tonometry, disc evaluation, (30-2) Humphrey field analyzer white on white (W/W) perimetry and short- wavelength automated perimetry. Thickness of the RNFL around the optic disc was determined with 3.4 mm diameter-wide OCT scans. Average and segmental RNFL thickness values were compared among all groups. A correlation was sought between global indices of perimetry and RNFL thickness. RESULTS: Of the 90 eyes enrolled (mean age of patients 52.32+/-10.11 years), the mean RNFL thickness was significantly less in ocular hypertensive (82.87+/-17.21 mm; P =0.008 and glaucomatous eyes (52.95+/-31.10 microm; P < 0.001), than in normals (94.26+/-12.36 microm). The RNFL was significantly thinner inferiorly in glaucomatous eyes (64.41+/-43.68 microm; P<0.001). than in normals (120.15+/-14.32 microm) and ocular hypertensives (107.87+/-25.79 microm; P<0.001). Ocular hypertensives had thinner RNFL in the nasal, inferior and temporal quadrants (P<0.001) when compared to normals. Global indices in ocular hypertensives on SWAP showed Mean Deviation (MD) of 5.32+/-4.49, Pattern Standard Deviation (PSD) 3.83+/-1.59 and Corrected Pattern Standard Deviation (CPSD) 2.84+/-1.85. The RNFL thickness could not be significantly correlated with global indices of visual fields in ocular hypertensives. CONCLUSION: Optical coherence tomography is capable of detecting changes at the level of RNFL in ocular hypertensive eyes with normal appearance of discs and W/W perimetry fields.     

Structure-function relationships using confocal scanning laser ophthalmoscopy, optical coherence tomography, and scanning laser polarimetry

PURPOSE: To assess the strength of the association between retinal nerve fiber layer (RNFL) thickness and optic disc topography measured with confocal retinal tomography (HRT II; Heidelberg Engineering, Dossenheim, Germany), optical coherence tomography (StratusOCT; Carl Zeiss Meditec, Inc., Dublin, CA), and scanning laser polarimetry (GDx with variable corneal compensator, VCC; Carl Zeiss Meditec, Inc.), and visual field (VF) sensitivity and to determine whether this association is better expressed as a linear or nonlinear function. METHODS: One hundred twenty-seven patients with glaucoma or suspected glaucoma and 127 healthy eyes from enrollees in the Diagnostic Innovations in Glaucoma Study (DIGS) were tested on HRT II, StratusOCT, GDx VCC, and standard automated perimetry (SAP, with the Swedish Interactive Thresholding Algorithm [SITA]) within 3 months of each other. Linear and logarithmic associations between RNFL thickness (HRT II, StratusOCT, and GDx VCC) and neuroretinal rim area (HRT II) and SAP sensitivity expressed in decibels were determined globally and for six RNFL/optic disc regions (inferonasal, inferotemporal, temporal, superotemporal, superonasal, and nasal) and six corresponding VF regions (superior, superonasal, nasal, inferonasal, inferior, and temporal). RESULTS: The associations (R2) between global and regional RNFL/optic disc measurements and VF sensitivity ranged from <0.01 (temporal RNFL, nasal VF, and nasal RNFL, temporal VF; linear and logarithmic associations) to 0.26 (inferotemporal RNFL, superonasal VF; logarithmic association) for HRT II; from 0.02 (temporal RNFL, nasal VF; linear association) to 0.38 (inferotemporal RNFL, superonasal VF; logarithmic association) for OCT; and from 0.03 (temporal RNFL, nasal VF; linear association) to 0.21 (inferotemporal RNFL, superonasal VF; logarithmic association) for GDx. Structure-function relationships generally were strongest between the inferotemporal RNFL-optic disc sector and the superonasal visual field and were significantly stronger for StratusOCT RNFL thickness than for other instruments in this region. Global associations (linear and logarithmic) were significantly stronger using OCT compared with HRT. In most cases, logarithmic fits were not significantly better than linear fits when visual sensitivity was expressed in log units (i.e., decibels). CONCLUSIONS: These results suggest that structure-function associations are strongest with StratusOCT measurements and are similar between HRT II and GDx VCC and these associations are generally no better expressed logarithmically than linearly when healthy, suspect, and glaucomatous eyes are considered.     

Relationship between parapapillary atrophy and visual field abnormality in primary open-angle glaucoma

PURPOSE: To investigate the relationship of parapapillary atrophy measured by confocal scanning laser ophthalmoscopy to visual field sensitivity measured with standard automated perimetry and short-wavelength automated perimetry in patients with primary open-angle glaucoma. METHODS: Forty-seven eyes of 47 primary open-angle glaucoma patients with increased intraocular pressure (> or = 22 mm Hg) were enrolled. Optic nerve head topography and parapapillary atrophy (beta and alpha zones) were assessed by confocal scanning laser ophthalmoscopy. Mean deviation and corrected pattern SD were assessed with standard automated perimetry and short-wavelength automated perimetry. RESULTS: Beta and alpha zones were found in 23 (49%) and 47 (100%) eyes with primary open-angle glaucoma, respectively. The area of beta zone showed significant correlations with MD of standard automated perimetry, corrected pattern SD of standard automated perimetry, and corrected pattern SD of short-wavelength automated perimetry (Spearman r = -0.366, P = .012; r = 0.327, P = .025; and r = 0.436, P = .002, respectively). The area of alpha zone showed a significant correlation with mean deviation of standard automated perimetry (r = -0.378, P = .009). Mean MD of standard automated perimetry, mean corrected pattern SD of standard automated perimetry, and mean corrected pattern SD of short-wavelength automated perimetry were significantly worse in eyes with beta zone than in eyes without beta zone. CONCLUSIONS: Parapapillary atrophy measured by confocal scanning laser ophthalmoscopy, especially beta zone, is associated with glaucomatous visual field loss demonstrated by standard automated perimetry and short-wavelength automated perimetry.