Comparison of ganglion cell and retinal nerve fiber layer thickness in primary open-angle glaucoma and normal tension glaucoma with spectral-domain OCT

Background

The aim of this study was to evaluate the macular thickness (MT), ganglion cell complex (GCC), and circum-papillary retinal nerve fiber layer (RNFL) thickness in primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG) with spectral domain optical coherence tomography (SD-OCT).

Methods

A total of 169 subjects were enrolled: 52 normal subjects, 61 with POAG, and 56 with NTG. Spectral-domain optical coherence tomography (SD-OCT) was used to analyze MT, GCC, and RNFL thickness. To compare the discrimination capabilities between the MT, GCC, and RNFL thickness measurements, we analyzed the areas under the receiver operating characteristic (ROC) curves (AUCs). The relationships between GCC and RNFL measurement and also the relationships of the groups, with age, gender, GCC, and RNFL thickness were assessed.

Results

Normal subjects showed the thickest superior and inferior GCC, followed by in order NTG and POAG (p?<?0.05). While there was a statistically difference in MT value of the normal subjects and the glaucoma patients (p?<?0.05), MT value did not differ between POAG and NTG (p?<?0.05). RNFL thickness parameters were significantly greater in normal subjects, followed in order by the NTG, and POAG (p?<?0.05). Between the normal and entire glaucoma groups, all GCC and RNFL parameters showed the similar discrimination power. RNFL thickness parameters correlated significantly with all GCC thickness (p?<?0.05). Superior RNFL thickness was the only independent variable between the POAG and NTG patients (odds ratio (OR) 0.942, p?=?0.004, 95 %CI 0.905–0.981).

Conclusions

SD-OCT evaluation results suggest higher GCC and RNFL parameters for NTG than POAG.     

Retinal vessel diameter in normal-tension glaucoma patients with asymmetric progression

Purpose

To investigate the longitudinal changes in the central retinal vessel diameter in asymmetric progressive normal-tension glaucoma (NTG) patients.

Methods

This study included 27 patients with bilateral NTG without any systemic vascular disease who showed glaucomatous progression in one eye at the mean follow-up of 24.3 months (range, 18–29 months). Progression was determined by the development of new retinal nerve fiber layer (RNFL) defects or widening of pre-existing defects on red-free RNFL photographs. The central retinal arteriolar equivalent (CRAE) and the central retinal venular equivalent (CRVE) were measured at baseline and at the mean follow-up of 24.3 months. We classified the eyes of each patient as either progressed or stable eyes, and compared the differences and changes in the CRAE and CRVE.

Results

No significant inter-eye difference was observed at baseline in the mean CRAE (167.5?±?22.2 μm vs. 168.2?±?15.5 μm, p?=?0.809) and in the mean CRVE (276.3?±?18.2 μm vs. 281.6?±?21.9 μm, p?=?0.267) between the progressed and stable eyes. There were significant changes in CRAE in the progressed eyes between baseline and 2 years after baseline (from 167.5?±?22.2 μm to 146.9?±?18.0 μm, p?p?=?0.084).

Conclusions

In our series of NTG patients with asymmetric progression, central retinal artery diameter decreased over time in the progressed eyes, whereas no significant decrease in the central retinal artery diameter was seen in the stable eyes.     

Relationship between disc margin to fovea distance and central visual field defect in normal tension glaucoma

Background

To investigate the relationship between ocular geometric factors, including temporal disc margin to fovea distance (DFD) measured by optic disc stereophotography (ODP) and central visual field (VF) defect, in normal-tension glaucoma (NTG) patients.

Methods

This retrospective, single-center, cross-sectional study included 88 eyes of 88 NTG patients with mild VF defects (MD?>??6.0 dB). NTG patients were divided into two groups according to VF tests: central VF-invading and central VF-sparing groups. Optic nerve head (ONH) parameters including disc dimensions, peripapillary atrophy (PPA), and DFD were obtained by ODP, and retinal nerve fiber layer (RNFL) thickness was measured by Stratus optical coherence tomography (OCT).

Results

In the invading group, DFD was shorter (3.642?±?0.401 mm) than in the sparing group (3.877?±?0.278 mm; p?=?0.002). The sparing group had more vertically oval ONH (p?=?0.023) and wider temporal PPA width (p?=?0.031). The RNFL thickness in the invading group was thinner in the temporal and inferior quadrants, but thicker in the superior quadrant than that of the sparing group. In a multiple linear regression analysis, DFD was the only geometric factor associated with degree of central VF involvement (p?=?0.002). DFD was positively correlated with temporal RNFL thickness in the sparing group (r?=?0.484, p?<?0.001) but not in the invading group (r?=??0.080, p?=?0.631).

Conclusions

Eyes with a shorter DFD should be monitored carefully because central VF involvement appears to be related to shorter DFD in NTG patients with mild VF defects.     

Pattern ERG and RNFL thickness in hypertensive eyes with normal blue-yellow visual field

Purpose

To evaluate the transient pattern electroretinogram (t-PERG) and the retinal nerve fiber layer (RNFL) thickness in eyes with ocular hypertension (OH) and normal short-wavelength automated perimetry (SWAP).

Methods

In 26 patients with bilateral OH with normal SWAP, and in 26 age and sex matched healthy controls, t-PERG recording and RNFL thickness measurement were performed. Mean deviation (MD) and pattern standard deviation (PSD) of a reliable full threshold 24-2 SWAP were considered. RNFL thickness was determined by OCT3. Monocular PERG were recorded by using a black and white checkerboard pattern (check size 0.9°, contrast 100 %, mean luminance 80 cd/m2) generated on a monitor and reversed in contrast (four reversals per second, 2 Hz) at a distance of 70 cm. Patients had optimal correction at viewing distance; no mydriatic or miotic eye drops were used. Silver/silver chloride skin electrodes were placed over the lower eyelids in the stimulated eye (active electrode) and in the patched eye (reference electrode); ground electrode was in the Fpz scalp. Peak-to peak amplitude of P50 (N35-P50) and N95 (P50-N95) waves, and implicit time of P50, were considered.

Results

Compared to controls, in OH eyes, a reduction of N35-P50 amplitude (2.86?±?1.49 vs. 3.77?±?1.08 microvolts, ?24.1 %, t-test p?=?0.015), of average RNFL thickness (88?±?11 vs. 96?±?10 μm, ?9.5 %, t-test p?=?0.002), and of RNFL thickness in superior (p?=?0.015) and inferior quadrant (p?<?0.001), were found. Multivariate analysis showed that in OH eyes, N35-P50 amplitude was inversely related to intraocular pressure (IOP) (p?=?0.001); no correlation was found between N35-P50 amplitude and MD, PSD, CCT or RNFL thickness.

Conclusions

In OH eyes, both PERG and RNFL thickness changes occur in hypertensive eyes with undamaged SWAP; the correlation of PERG amplitude with IOP, but not with RNFL thickness, suggests that such PERG changes are an effect of the IOP on retinal ganglion cells, rather than a sign of their loss.     

Pattern electroretinogram in neuromyelitis optica and multiple sclerosis with or without optic neuritis and its correlation with FD-OCT and perimetry

Purpose

To evaluate the ability of transient pattern electroretinogram (PERG) parameters to differentiate between eyes of patients with neuromyelitis optica (NMO), longitudinally extensive transverse myelitis (LETM), multiple sclerosis with optic neuritis (MS + ON), multiple sclerosis without optic neuritis (MS ? ON), and controls, to compare PERG and OCT with regard to discrimination ability, and to assess the correlation between PERG, FD-OCT, and visual field measurements (VFs).

Methods

Visual field measurements and full-field stimulation PERGs based on both 48- and 14-min checks were obtained from patients with MS (n = 28), NMO (n = 20), LETM (n = 18), and controls (n = 26). In addition, FD-OCT peripapillary retinal nerve fiber layer (RNFL) and segmented macular layer measurements were obtained and their correlation coefficients were determined.

Results

Compared to controls, PERG amplitude measurements were significantly reduced in eyes with NMO and MS + ON, but not in eyes with LETM and MS ? ON. PERG amplitudes were significantly smaller in NMO and MS + ON eyes than in MS ? ON eyes. PERG and OCT performance was similar except in NMO eyes where macular thickness parameters were more efficient at detecting abnormalities. A significant correlation was found between N95 amplitude values and OCT-measured macular ganglion cell layer thickness, total retinal thickness, and temporal peripapillary RNFL thickness. PERG amplitude was also significantly associated with VF sensitivity loss. No statistically significant difference was observed with regard to the best-performing parameters of the two methods.

Conclusions

Pattern electroretinogram measurements were able to detect RNFL loss in MS + ON and NMO eyes, with a performance comparable to OCT. PERG amplitude measurements were reasonably well correlated with OCT-measured parameters.     

Measurement of retinal nerve fiber layer and macular ganglion cell–inner plexiform layer with spectral-domain optical coherence tomography in patients with optic nerve head drusen

Purpose

To evaluate the effect of optic nerve head drusen (ONHD) on the retinal nerve fiber layer (RNFL) and macular ganglion cell–inner plexiform layer (GCIPL) using Cirrus optical coherence tomography (OCT).

Methods

Fifty-seven eyes of thirty patients with ONHD and thirty-eight eyes of twenty age-matched and sex-matched control subjects underwent circumpapillary and macular scanning using Cirrus OCT. The percentages of eyes with abnormal GCIPL and RNFL values according to the Cirrus normative data were analysed and compared.

Results

Overall, eyes with ONHD showed abnormally reduced values for average and minimum GCIPL thicknesses in 35 % and 45 % of cases compared to 2 % for both values in control eyes (P?p?=?0.002). The percentage of abnormal thinning increased with higher grades of ONHD for all the parameters evaluated, so that in grade III drusen, values were abnormally reduced in 80 % of eyes in all three analyses. Regarding buried ONHD, 30 % and 4 % of eyes had an abnormally reduced minimum GCIPL and average RNFL thickness, respectively. Furthermore, 26 % of these eyes had abnormal GCIPL exams with a normal or increased RNFL thickness.

Conclusions

Both RNFL and GCIPL analysis reveal significant thinning in eyes with ONHD directly correlated with drusen severity. In buried ONHD, the abnormality rate was significantly higher with GCIPL compared to RNFL evaluation, suggesting that GCIPL analysis might be an early structural indicator of neuronal loss in the setting of thickened RNFL.     

Evaluation of relationship between retinal nerve fiber layer thickness progression and visual field progression in patients with glaucoma

Purpose

To evaluate the capability of optical coherence tomography (OCT), retinal nerve fiber layer (RNFL) thickness, and visual field (VF) measurements in glaucoma progression detection.

Methods

The study examined 62 eyes of 37 glaucoma patients observed over a 3-year period. All eyes underwent at least four serial RNFL measurements performed by Cirrus OCT, with the first and last measurements separated by at least 3 years. VF testing was performed by using the Swedish interactive threshold algorithm (SITA) Standard 30-2 program of the Humphrey field analyzer (HFA) on the same day as the RNFL imaging. Both serial RNFL thicknesses and VF progression were assessed by the guided progression analysis (GPA) software program. RNFL thickness progression was evaluated by event analysis. Total deviation (TD) in the superior or inferior hemifield was also examined.

Results

A total of 295 OCT scans and 295 VFs were analyzed. Five eyes exhibited progression by OCT only and 8 eyes exhibited progression by VF GPA only. When the analysis was based on the combined measurement findings, progression was noted in 6 eyes. The average of the progressive hemifield TD at baseline for combined RNFL and VF progression was ?3.21 ± 1.38 dB, while it was ?2.17 ± 1.14 dB for RNFL progression and ?9.12 ± 3.75 dB for VF progression. The average of the progressive hemifield TD indicated a significant advancement of VF progression as compared to RNFL progression (P = 0.002).

Conclusions

When a mild VF defect is present, OCT RNFL thickness measurements are important in helping discern glaucoma progression.     

Evaluation of optic disc,retinal nerve fiber and macular ganglion cell layers in pediatric diabetes

Purpose

Our aim was to compare optic disc parameters, retinal nerve fiber (RNFL) and macular ganglion cell layers between children and adolescents with diabetes mellitus (type 1) and healthy controls.

Methods

Sixty-three eyes of 63 pediatric diabetic patients without diabetic retinopathy and 44 eyes of 44 healthy controls were included in this cross-sectional and comparative study. Diabetic and control groups were similar in the aspect of age, gender and refractive error. Measurements of optic disc parameters (i.e., rim area, disc area, cup-to-disc ratio, cup volume), thickness of RNFL and macular ganglion cell—inner plexiform layers (GCL + IPL) were taken with the spectral domain optical coherence tomography.

Results

There were not statistically significant differences between the diabetic patients and healthy controls in terms of intraocular pressure (p = 0.14), retinal nerve fiber layer thickness (p = 0.61), rim area (p = 0.92), disc area (p = 0.10), vertical cup-to-disc ratio (p = 0.16), cup volume (p = 0.13), and average macular GCL + IPL thickness (p = 0.43). On the other hand, binocular RNFL thickness symmetry percentage was statistically significantly different in the diabetic and control groups (p = 0.01).

Conclusion

Diabetic children and adolescents without diabetic retinopathy have more binocular RNFL thickness asymmetry compared to healthy controls.

     

Novel use of 3T MRI in assessment of optic nerve volume in glaucoma

Purpose

To measure optic nerve (ON) volume using 3 T magnetic resonance imaging (MRI), to correlate ON volume with retinal nerve fiber layer (RNFL) thickness, and to determine the viability of MRI as an objective tool in distinguishing glaucoma severity.

Methods

In this cross-sectional study, 30 severe glaucoma patients, 30 mild glaucoma patients and 30 age-matched controls were recruited. All subjects underwent standard automated perimetry, RNFL analysis and 3 T MRI examinations. Glaucoma patients were classified according to the Hodapp–Anderson–Parish classification. Pearson’s correlation coefficient was used to correlate ON volume with RNFL, and receiver operating curve (ROC) analysis was performed to determine the sensitivity and specificity of ON volume in detecting glaucoma severity.

Results

Optic nerve volume was significantly lower in both the left and right eyes of the severe glaucoma group (168.70?±?46.28 mm³; 167.40?±?45.36 mm³) than in the mild glaucoma group (264.03?±?78.53 mm³; 264.76?±?78.88 mm³) and the control group (297.80?±?71.45 mm³; 296.56?±?71.02 mm³). Moderate correlation was observed between: RNFL thickness and ON volume (r?=?0.51, p <0.001), and in mean deviation of visual field and optic nerve volume (r?=?0.60, p?<?0.001). ON volume below 236 mm³ was 96 % sensitive and 80 % specific for the detection of severe glaucoma.

Conclusions

MRI measured optic nerve volume is a reliable method of assessing glaucomatous damage beyond the optic nerve head. A value of 236 mm³ and below can be used to define severe glaucoma.     

A comparison of false positives in retinal nerve fiber layer,optic nerve head and macular ganglion cell-inner plexiform layer from two spectral-domain optical coherence tomography devices

Background

The incidence of false positive (FP) results of optic coherence tomography (OCT) retinal nerve fiber layer (RNFL) color code in healthy subjects can be very high with Cirrus OCT. Recent evidence has shown that OCT parameters derived from macular ganglion cell-inner plexiform layer (GCIPL) have excellent ability to discriminate between normal eyes and eyes with early glaucoma.

Methods

This was a prospective, cross-sectional study. One hundred eyes from 50 healthy volunteers underwent circumpapillary scanning by Cirrus and Spectralis OCT and macular scanning using Cirrus OCT. FP rates for each of the OCT parameters, using predefined criteria for an abnormal test were calculated. Comparative analysis was performed using the McNemar test. A generalized estimating equations model (GEE) was used to compare demographic and clinical factors between the eyes with normal findings and eyes with abnormal results.

Results

The overall RNFL color-code FP rate was significantly higher for Cirrus (39 %) than for Spectralis (18 %) (P?=?0.000). The Spectralis RNFL FP rate showed no significant difference when compared to the FP rate by Cirrus GCIPL (13 %) and ONH (11 %) analysis. Axial length, mean spherical equivalent, presence of peripapillary atrophy, and tilted disc were significantly related to the RNFL FP occurrence displayed by both devices.

Conclusions

Spectralis might be more specific than Cirrus when evaluating the RNFL thickness for Caucasians and moderate myopic population. GCIPL and ONH analysis might be more useful than RNFL thickness to evaluate this population using Cirrus OCT.     

Clinical features and glaucoma according to optic disc size in a South Korean population: the Namil study

Purpose

To assess the proportion of glaucomatous eyes based on the association between optic disc (OD) size and its clinical determinants in the resident population of Namil-myon, Central South Korea.

Methods

Of the 1,532 participants in the Namil study, we included 1,410 Koreans (2,734 eyes) with legible fundus photographs in this study. Following the estimation of OD size on the photographs using Image J software, we corrected for image magnification. Associations between the clinical features, such as age, sex, axial length (AL), spherical equivalent (SE), and central corneal thickness, and the estimated OD size were assessed for individual eyes. After adjusting for the influencing factors, the proportion of glaucoma was compared among three categories of measured OD size (small, medium, and large OD groups).

Results

After adjusting for the potential confounders using a linear mixed model, age, sex, AL, and SE were correlated with the OD size estimates (P = 0.003, P = 0.029, P < 0.001, and P < 0.001, respectively). The percentage of glaucomatous eyes was 3.77 % in the small disc group, which was higher than in the other groups (P = 0.054). In particular, normal tension glaucoma (NTG) was statistically significantly more frequent in this group (odds ratio = 1.86, P = 0.042).

Conclusions

These results suggest that clinical features such as age, sex, AL, and SE might need to be considered for an accurate evaluation of the OD. In addition, in individuals with a small OD, the presence of NTG must be carefully investigated in the South Korea population.     

Comparison of ability of time-domain and spectral-domain optical coherence tomography to detect diffuse retinal nerve fiber layer atrophy

Purpose

Our aim was to evaluate and compare diagnostic capabilities of time-domain (Stratus) and spectral-domain (Cirrus) optical coherence tomography (OCT) to detect diffuse retinal nerve fiber layer (RNFL) atrophy.

Methods

This study assessed 101 eyes from 101 glaucoma patients with diffuse RNFL atrophy and 101 eyes from 101 age-matched healthy individuals. Two experienced glaucoma specialists graded red-free RNFL photographs of eyes with diffuse RNFL atrophy using a four-level grading system. The area under the receiver operating characteristic curves (AUC) of normal eyes was compared with that of eyes with diffuse atrophy. Sensitivity and specificity of each OCT device were calculated on the basis of its internal normative database.

Results

The largest AUC for Stratus and Cirrus were obtained for average RNFL thicknesses (0.96 and 0.94, respectively). Comparison of the AUC with different RNFL atrophy grades revealed no significant difference between the two OCT devices. Using an internal normative database at a <5 % level, the overall sensitivity of Stratus ranged from 58.0 to 84.0 %, whereas that of Cirrus ranged from 75.0 to 87.0 %. According to the normative database, the highest Stratus sensitivity was obtained with the temporal–superior–nasal–inferior–temporal (TSNIT) thickness graph, and the highest Cirrus sensitivity with the TSNIT thickness graph and the deviation map.

Conclusions

The AUC obtained from Cirrus were comparable with those from Stratus. On the basis of their normative databases, these devices had similar diagnostic accuracy. Our results suggest that the diagnostic capabilities of the two instruments to detect diffuse RNFL atrophy are similar.     

Evaluating retinal vessel diameter with optical coherence tomography in normal-tension glaucoma patients

Purpose

To investigate a novel optical coherence tomography (OCT)-derived variable, circumpapillary mean retinal shadow width (cpMRSW), and to elucidate its association with normal-tension glaucoma (NTG).

Methods

For the purpose of validation, we measured retinal vascular calibers in 68 arterioles and 100 venules of 12 NTG patients and 12 healthy subjects and compared the width of the visible retinal shadows in spectral-domain OCT images and the caliber of retinal vessels in retinal photographs. Then we calculated cpMRSW in 78 NTG eyes and 25 age-matched healthy control eyes. Additionally, we divided the patients into early (mean deviation: MD > ?6 dB), moderate (MD ?6 to ?12 dB), and severe (MD < ?12 dB) NTG groups, and compared cpMRSW in these groups. Finally, we calculated the area under the receiver operating characteristic (ROC) curve in order to determine the power of mean retinal shadow width to distinguish the groups.

Results

OCT retinal shadow width was significantly correlated with photography-measured retinal caliber (r = 0.82, P < 0.001). CpMRSW was significantly different between the control and NTG patients (control: 107.3 ± 7.0 µm, mild: 99.4 ± 8.6 µm, moderate: 99.7 ± 9.5 µm, severe: 90.5 ± 12.0 µm, P < 0.001), despite similar distributions in systemic variables. An ROC analysis revealed that cpMRSW could differentiate NTGs from normal eyes (area under the ROC curve: 0.81).

Conclusions

Our new software for measuring mean retinal shadow width in OCT images may be a valuable tool for detecting NTG and diagnosing its severity.

     

Structural and functional assessment by hemispheric asymmetry testing of the macular region in preperimetric glaucoma

Purpose

To investigate structural measurements of the macular area in preperimetric glaucoma (PG) patients using spectral domain optical coherence tomography with two functional measurements [10-2 Humphrey visual field (HFA) and 10-2 Microperimeter-1 (MP-1)] and by macular symmetry testing.

Methods

Fifteen eyes of 15 PG subjects with a retinal nerve fiber layer defect in the inferior hemisphere and 15 eyes of 15 normal control subjects were enrolled. Macular symmetry testing was performed between the superior and inferior zones by comparing zone thickness in each hemisphere. Perimetric sensitivity asymmetry was calculated with two functional measurements. Structure–function relationships between macular symmetry testing and the mean retinal sensitivity of the corresponding hemifield or perimetric sensitivity asymmetry were calculated using Spearman’s rank correlation and linear regression.

Results

Macular zone thickness in the abnormal hemispheres was significantly less than that in normal hemispheres in PG eyes and the corresponding hemispheres in control eyes (P < 0.001). Macular symmetry testing was significantly lower in PG eyes compared to control eyes (P < 0.001). HFA (10-2) and MP-1 (10-2) correlated significantly (rs = 0.81, P < 0.0001). Macular symmetry testing values were significantly correlated with perimetric sensitivity and perimetric sensitivity asymmetry with two functional measurements (rs = 0.61, P = 0.02; HFA and rs = 0.68, P = 0.006; MP-1).

Conclusions

Our results suggest that macular asymmetry analysis can reveal the structure–functional relationship in PG eyes.     

Peripapillary retinal nerve fiber layer thickness in preeclampsia and eclampsia

Purpose

To evaluate peripapillary retinal nerve fiber layer (RNFL) thickness during and after pregnancy in pregnant women with preeclampsia or eclampsia and compare it with normotensive pregnant women as controls.

Methods

In a prospective comparative case–control study 35 women (70 eyes) with mild to moderate preeclampsia, 70 women (140 eyes) with severe preeclampsia and eclampsia, and 44 (88 eyes) healthy pregnant women were enrolled in three groups. Peripapillary RNFL thickness in three groups was measured after 28 weeks of pregnancy and 2 months postpartum by using optical coherence tomography. Mean and quadratic RNFL thickness changes were compared within and among the groups.

Results

Mean peripapillary RNFL thickness decreased significantly from 104 ± 10, 104 ± 23, and 106 ± 9 µm during pregnancy to 101 ± 10, 96 ± 10, and 103 ± 9 µm 2 months after pregnancy in the mild to moderate preeclampsia, severe preeclampsia and eclampsia, and healthy pregnant women groups, respectively (P < 0.001 for all). While the difference among the groups was insignificant during pregnancy, it reached to a significant level after delivery (P = 0.006). The highest reduction in mean RNFL thickness (6 ± 10 µm) occurred in the severe preeclampsia and eclampsia groups.

Conclusions

In relation to the time of pregnancy, peripapillary RNFL reduced in preeclamptic and eclamptic cases as well as in normotensive pregnant women at 2 months postpartum. This reduction was more in the severe forms of pregnancy-induced hypertension.

     

Comparison of Spectralis-OCT, GDxVCC and GDxECC in assessing retinal nerve fiber layer (RNFL) in glaucomatous patients

Background

Glaucomatous optic neuropathy is characterized by a progressive loss of retinal ganglion cells (RGCs). The defects in the peripapillary retinal nerve fiber layer (RNFL) have been reported to be the earliest sign of glaucoma. We determined the agreement between RNFL thickness assessments from spectral-domain OCT (Spectarlis HRA?+?OCT; Heidelberg Engeneering, Heidelberg, Germany), scanning laser polarimetry (SLP) with variable cornea compensation (GDxVCC; Carl Zeiss Meditec, Dublin, CA, USA), and SLP with enhanced cornea compensation (GDxECC; Carl Zeiss Meditec, Dublin, CA, USA) in glaucomatous patients. Furthermore, we investigate the influence of typical scan score (TSS) on the results of GDx assessments.

Methods

The enrolled subjects were devided into different groups by modified HODAPP visual field criteria. The peripapillary RNFL thickness was assessed with the three devices . ANOVA test, Pearson and Spearman correlation coefficient, and Bland-Altman plots were used to analyse the RNFL thickness assessments.

Results

Ninety-two eyes from 92 glaucomatous subjects were analysed. These were divided into four groups: preperimetric glaucoma (n?=?26), mild glaucoma (n?=?18), moderate glaucoma (n?=?21), and severe glaucoma (n?=?27). For Spectralis-OCT, the average RNFL thickness (mean ± SD) was 99.25?±?26.31 μm, 80.52?±?16.63 μm, 71.59?±?21.15 μm, and 63.85?±?20.86 μm for preperimetric, mild, moderate, and severe glaucoma respectively. For GDxVCC, the corresponding assessments were 52.63?±?8.18 μm, 52.95?±?10.20 μm, 46.77?±?10.62 μm, and 49.70?±?13.34 μm. For GDxECC, the assessments were 49.35?±?6.52 μm, 45.92?±?7.21 μm, 42.19?±?8.00 μm, and 39.53?±?8.45 μm. All Spectralis-GDxVCC and Spectralis-GDxECC differences were statistically significant by ANOVA test. The differences between GDxVCC and GDxECC were statistically significant only for severe glaucoma. There was a highly significant correlation between Spectralis-OCT and GDxECC, as well as Spectralis-OCT and GDxVCC, in assessing the RNFL thickness. The best instrument agreement was found between GDxECC and Spectralis-OCT. The RNFL thickness assessed with Spectralis-OCT and GDxECC showed a better correlation to visual field defects than GDxVCC. Evaluating GDx assessments with typical retardation pattern GDxVCC and GDxECC showed very similar RNFL thickness results.

Conclusions

RNFL thickness assessments between GDxVCC, GDxECC, and Spectralis-OCT cannot be directly compared. The assessments are generally higher with Spectralis-OCT than with GDxVCC and GDxECC, because of differences in method of the devices. The atypical retardation pattern has a major impact on the RNFL thickness results of GDx devices. This must be taken into account when evaluating the assessed RNFL thickness results.     

Reproduzierbarkeit der Messung der peripapillären Nervenfaserschichtdicke

Purpose

The aim of this study was to compare the intra- and inter-examiner reproducibility of measurements obtained by optical coherence tomography (OCT) and retinal thickness analyzer (RTA).

Patients and methods

During a period of 2 months, 22 eyes of 16 patients and 6 healthy subjects were included. Two examiners (EMH, RK) successively performed three measurements of the peripapillary retinal nerve fibre layer (RNFL) thickness with RTA and OCT. The reproducibility of three individual measurements of one examiner (intra-examiner) as well as the reproducibility of the measurements between both examiners (inter-examiner) was evaluated using the Friedman test and sign test.

Results

The average thickness of the peripapillary RNFL was 154.4 µm for the first investigator (EMH) and 155.1 µm for the other investigator (RK) measured with RTA. The results obtained by OCT were 137.3 µm (EMH) and 138.9 µm (RK), respectively, generally indicating a threefold smaller range. Comparing the three measurements of one single examiner, no appreciable intra-observer dependency neither for RTA (EMH: p=0.19, RK: p=0.95) nor for OCT (EMH: p=0.51, RK: p=0.62) was observed. Inter-examiner analysis for RTA and OCT also revealed an acceptable reproducibility.

Conclusions

Measurements of peripapillary RNFL thickness using RTA and OCT exhibited intra- and inter-observer agreement.     

Development of a new strategy of visual field testing for macular dysfunction in patients with open angle glaucoma

Purpose

To explore methods of automated visual field (VF) examination for the assessment of macular function.

Method

We used a VF examination (AP-7000 automatic perimeter, Kowa, Japan) to examine macular function in 53 eyes from 29 patients with open angle glaucoma. We measured the mean total deviation (c-MD) of 16 points in the central VF located in a 2-degree-interval 4 × 4 array with various stimulus sizes (Goldmann sizes III, II, and I). The retinal nerve fiber layer (RNFL) thickness, ganglion cell complex (GCC), and ganglion cell layer plus inner plexiform layer (GCL + IPL) were measured with the 3D OCT-2000 System (Topcon, Japan). The c-MDs of various stimulus sizes were compared with the OCT parameters using the Spearman rank correlation.

Results

The average examination time was 93.5 ± 23.5 s and the c-MD values were ?11.8 ± 8.2 (stimulus size III), ?11.9 ± 9.5 (stimulus size II), and ?12.3 ± 9.6 dB (stimulus size I). The c-MD (stimulus size III) and averaged total deviations of the Humphrey Field Analysis 10-2 program were significantly correlated (ρ = 0.91). The C-MD values for stimulus size III were significantly correlated with the OCT parameters (RNFL: ρ = 0.59; GCC: ρ = 0.65; and GCL + IPL: ρ = 0.64). The correlation coefficient between the c-MD and the GCC was better for stimulus sizes II and I (ρ = 0.69) than for stimulus size III (ρ = 0.65).

Conclusion

The C-MD values for the 16 measured central VF points were significantly correlated with macular structure, and the smaller stimulus sizes of the automated VF test had a higher correlation coefficient of within 8°.     

Scanning laser ophthalmoscopic parameters of eyes with exfoliation syndrome

Purpose

To evaluate optic nerve head (ONH) characteristics in patients with exfoliation syndrome (EXS).

Methods

This was a cross-sectional, observational study in which 73 eyes from 73 patients with EXS and 93 eyes from 93 age-matched healthy subjects who met the inclusion criteria were included. Topographic measurements of the ONH and peripapillary retinal nerve fiber layer (RNFL) thickness were performed by confocal scanning laser ophthalmoscopy, using a Heidelberg retina tomograph. Outcomes of interest were studied by Student t test and χ-squared test.

Results

EXS patients and age-matched controls did not differ in ONH parameters. Nevertheless, the mean cup depth and height variation contour values were higher in the normal subjects (P = 0.07, P = 0.056, respectively). Mean RNFL thickness was 0.22 ± 0.06 mm in the EXS group and 0.26 ± 0.06 mm in the control group, (P = 0.001). Likewise, the RNFL cross-sectional area was significantly lower in exfoliative eyes (1.16 ± 0.35 mm²) than in those of the control group (1.31 ± 0.33 mm²) (P = 0.006).

Conclusions

No significant differences in ONH parameters between EXS patients and age-matched healthy subjects were observed; however, RNFL measurements in eyes with EXS showed lower values.     

Relationship between corneal hysteresis and optic nerve parameters measured with spectral domain optical coherence tomography

Background

Corneal hysteresis (CH) has been associated with visual field damage in glaucoma and is related to the velocity of perimetric glaucoma progression. We undertook this investigation to determine whether CH is associated with structural markers of glaucoma damage on spectral domain optical coherence tomography (SD-OCT).

Methods

In this retrospective study, 131 patients under glaucoma evaluation were evaluated with SD-OCT (Cirrus; Carl Zeiss Meditec, Dublin, CA) and had CH measurements with the ocular response analyzer (Reichert, Inc., Buffalo, NY). Pearson and partial correlation adjusting for age were preformed to examine the association between CH and variables of interest. Generalized estimating equations were used to construct simple and multiple linear models.

Results

While Pearson correlations were modest overall, CH best correlated with mean deviation (MD; r?=?0.19) followed by average retinal nerve fiber layer (RNFL) thickness (r?=?0.18) and vertical cup to disc ratio (r?=??0.11) in the open angle glaucoma group. In univariable models, CH varied as a function of MD (ß?=?0.1, 95 % CI 0.03, 0.1; p?<?0.001) and of average RNFL thickness (ß?=?0.2, 95 % CI 0.1, 0.4; p?=?0.001). In a multivariable analysis including MD, age, average RNFL thickness, and glaucoma status, MD (p?=?0.001) and age (p?<?0.001) retained significant associations with CH.

Conclusions

In patients under evaluation and treatment for glaucoma, CH was more closely related to visual field MD than to structural markers of glaucoma damage as measured by SD-OCT.