Cup-disc Area Ratio Research Articles

Evaluation of visual field changes with retinal nerve fiber layer thickness in primary congenital glaucoma.

To evaluate visual field changes in primary congenital glaucoma (PCG) with retinal nerve fiber layer thickness on optical coherence tomography. In this cross-sectional, observational study, consecutive PCG children who underwent combined trabeculotomy with trabeculectomy and on regular follow-up were enrolled. All patients were aged over four years and co-operative for RNFL OCT and visual field examination. Perimetry was done on Humphrey visual field (HVF) analyzer using 30-2 and 10-2 SITA standard algorithms as appropriate. If a reliable automated perimetry was not feasible, kinetic perimetry was done. The following were noted at baseline and every follow-up: age, sex, visual acuity, intraocular pressure (IOP), cup-disc ratio (CDR), corneal diameters, refraction, any topical antiglaucoma medications, surgeries underwent, age at surgery and duration between surgery and final examination. Forty-eight eyes of 34 children operated for PCG and 19 eyes of 17 controls were analyzed. A statistically significant thinner average RNFL thickness of 87.2 ± 28 μm was noted in PCG eyes as compared to controls with 100.6 ± 7.2 μm (P = 0.04). The mean cup-disc area ratio on OCT in PCG eyes was 0.43 ± 0.2 (0.02-0.93) and in control eyes was 0.23 ± 0.07 (0.1-0.4) (P < 0.001). On RNFL OCT, there was significant focal RNFL loss in temporal superior (P = 0.003), nasal inferior (P = 0.037) and temporal inferior (P < 0.001) quadrants compared to controls. Among PCG eyes, 20/48 eyes (41.7%), had definitive, reproducible glaucomatous VF defects. Mean baseline IOP in PCG eyes with VF defect was 28.7 ± 5.7 mmHg and in eyes with normal VF was 24.6 ± 5.9 mmHg (P = 0.03). On univariate regression analysis, higher baseline IOP was significantly associated with both RNFL loss (odds ratio (OR): -2.17) and VF defects (OR: 3.35). Fluctuation in follow-up IOP (OR: 3.33) was also significantly associated with the presence of VF defects. On multivariable regression analysis maximum, IOP was significantly associated with RNFL loss and VF defects. Peripapillary RNFL thickness could be used to identify PCG eyes having visual field loss and possibly poor visual function from PCG eyes without visual field defects. Baseline and follow-up IOP, significantly correlated with RNFL thickness in PCG eyes.

Comparison of imaging parameters between OCT, GDx and HRT in the Northern Finland birth cohort eye study.

The purpose of the study was to assess and compare the optic nerve head (ONH) and retinal nerve fibre layer (RNFL) parameters and image quality parameters obtained by Cirrus HD-OCT, GDxECC and HRT3 in a population-based screening study. This analysis examined 2566 subjects taking part in the Northern Finland Birth Cohort Eye study. Images with spectral domain OCT (Cirrus HD-OCT 4000), scanning laser ophthalmoscopy (HRT3) and scanning laser polarimetry (GDxECC) were obtained from each subject. The correlation of average and regional parameters of RNFL and ONH between devices was evaluated. The RNFL thickness was 90.9 µm when measured with OCT, 24.6 µm with HRT and 48.1 µm with GDx. There was a high correlation between the disc and cup measurements with the HRT and OCT and the RNFL thickness of the OCT and GDx (r > 0.5). A statistically significant correlation was found between RNFL measurements of the HRT and OCT in the superior, temporal and inferior quadrants. Optical coherence tomography (OCT) signal strength correlated with the image quality parameters of the HRT and GDx. The percentage of good quality images was the lowest with the GDx. The RNFL thickness in Northern Finland birth cohort was at a lower level compared to other studies. The study confirms the difference in measuring ONH parameters between the imaging devices. However, significant correlations between devices were found in the cup volume and cup disc area ratio parameters of the OCT and HRT. The correlations between image quality parameters and glaucoma detection parameters were relatively low.

Structural Characterization of Glaucoma Patients with Low Ocular Blood Flow

ABSTRACT Purpose: There is an unclear relationship between ocular blood flow (OBF) and the structural characteristics of the optic nerve head (ONH) in glaucoma, a multifactorial disease. This study used laser speckle flowgraphy (LSFG) to identify low-OBF glaucoma patients and investigated the ONH in these patients. Materials and Methods: In 533 eyes with glaucoma, we determined confounding factors for LSFG-measured OBF (tissue-area mean blur rate: MT) and corrected MT with a linear mixed-effects model (LMM). Structural ONH data (from fundus stereo photography), OCT data, and clinical characteristics were then compared in patients with corrected MT in the upper and lower quartiles using the LMM. Results: Single regression showed significant correlations between MT and age, spherical equivalent (SE), central corneal thickness (CCT), and a weighted count of retinal ganglion cells (wRGC), but not axial length or systemic blood pressure. Gender also significantly influenced MT; MT was corrected for these correlated factors and also glaucoma type with the LMM. The lower-quartile MT group had a significantly larger cup area and cup-disc area ratio and lower temporal quadrant circumpapillary retinal nerve fiber layer thickness (cpRNFLT) and macular ganglion cell complex (GCC) than the upper-quartile group. Conclusions: Low-OBF glaucoma patients were characterized by a larger cup-disc ratio, and higher susceptibility to damage in the temporal disc and the macular area.

Multi-trait genome-wide association study identifies new loci associated with optic disc parameters

A new avenue of mining published genome-wide association studies includes the joint analysis of related traits. The power of this approach depends on the genetic correlation of traits, which reflects the number of pleiotropic loci, i.e. genetic loci influencing multiple traits. Here, we applied new meta-analyses of optic nerve head (ONH) related traits implicated in primary open-angle glaucoma (POAG); intraocular pressure and central corneal thickness using Haplotype reference consortium imputations. We performed a multi-trait analysis of ONH parameters cup area, disc area and vertical cup-disc ratio. We uncover new variants; rs11158547 in PPP1R36-PLEKHG3 and rs1028727 near SERPINE3 at genome-wide significance that replicate in independent Asian cohorts imputed to 1000 Genomes. At this point, validation of these variants in POAG cohorts is hampered by the high degree of heterogeneity. Our results show that multi-trait analysis is a valid approach to identify novel pleiotropic variants for ONH.

Optic disc morphology in unilateral branch retinal vein occlusion using spectral domain optical coherence tomography.

BackgroundThe aim of this study was to evaluate the association between optic nerve head (ONH) parameters and branch retinal vein occlusion (BRVO) using spectral domain optical coherence tomography (SD-OCT).MethodsBoth eyes of 40 patients with unilateral BRVO (mean age: 67.4 ± 11.4 years, male: female - 18:22) were enrolled in this study. Control group consisted of randomly selected single healthy eyes of 40 age and gender matched volunteers (mean age: 64.7 ± 15.4 years, male: female - 16:24). ONH parameters (including optic disc area, optic cup area, neuroretinal rim area, cup volume, rim volume, cup-disc area ratio, horizontal and vertical cup-disc ratio, average retinal nerve fiber layer) were measured by SD-OCT. Axial length (AL) of the eyes was measured by non-contact optical low coherence reflectometry. The ONH parameters of eyes with BRVO were compared with those of fellow eyes using mixed model, one-way between-groups analysis of covariance was conducted to compare the ONH parameters of affected and unaffected fellow eyes in BRVO patients with those of the control eyes keeping confounding factors, including AL, age and gender under control in the statistical analysis.ResultsNone of the investigated ONH parameters of affected BRVO eyes, unaffected fellow eyes and control eyes were statistically different after controlling for AL, age and gender.ConclusionOptic disc morphology might not be a potential anatomical predisposing factor for development of BRVO.Electronic supplementary materialThe online version of this article (doi:10.1186/s12886-015-0165-1) contains supplementary material, which is available to authorized users.

Comparison between the measurements of different parameters obtained from optic nerve head analysis by using Heidelberg retinal tomography (HRT3) and Optical coherence tomography (Stratus OCT)

Purpose: A cross-sectional prospective nonrandomized study was undertaken to find out whether Heidelberg retinal tomography (HRT3) and Optical coherence tomography (Stratus OCT) could be used interchangeably for the measurement of different parameters of optic nerve head in clinical practice. Materials and Methods: Measurements of disc area, cup area, rim area and cup-disc area ratio were obtained with the HRT3 and Stratus OCT printouts in 18 patients aged 20 to 70 years. True agreements between methods in measuring disc area, cup area, rim area and cup-disc area ratio were assessed using Bland-Altman statistical analysis. Eighteen patients with a mean age of 27.05 ± 5.04 years were enrolled. Result: Differences between mean (bias) were -0.81 ± 0.58 mm2 for disc area, -0.31 ± 0.32 mm2 for cup area,-0.50 ± 0.64 mm2 for rim area, -0.04 ± 0.09 for cup-disc area ratio while using HRT3 and Stratus OCT, respectively. Conclusion: Large range of differences were observed in measurements of disc area, cup area, rim area and cup-disc area ratio with HRT3 and Stratus OCT.

Parameters measurement of the optic nerve head and macular ganglion cell complex in patients with preperimetric glaucoma

Objective To observe the changes of glaucoma optic nerve head (ONH) parameters and macular ganglion cell complex (GCC) structure in preperimetric glaucoma (PPG) patients.Methods Eighteen PPG patients (18 eyes,PPG group),22 primary open-angle glaucoma (POAG) patients (22 eyes,POAG group),and 20 patients (20 eyes) with physiologic large optic cup (physiological big optic cup group) were included in this study.Seventeen healthy volunteers (17 eyes) were the normal control.The optic nerve head and macular was scanned by fourier-domain optic coherence tomography (FD-OCT) for all subjects.The following 15 parameters,including nerve fiber layer thickness (RNFL),the optic disk rim volume (RV),optic nerve head volume (NHV),optic disc area (ODA),rim area (RA),cup volume (CV),cup/disc area ratio (CDAR),vertical cup/disc ratio (VCDR),horizontal cup/disc ratio (HCDR) and optic cup area (CA),macular GCC,superior GCC,inferior GCC thickness,focal loss of volume (FLV) and global loss of volume (GLV),were measured at 10 different quadrants.The relationship between macular GCC thickness or optic disc RNFL thickness and RA was analyzed by simple linear regression analysis.Results The RNFL thickness of PPG patients was (99.29±19.93) μm (superior quadrant),(97.29±22.86) μm (inferior),(114.61±15.64) μm (superior temporal,ST),(119.22±26.19) μm (inferior temporal,IT),(116.11±39.32) μm (superior nasal,SN),(111.33±37.65) μm (inferior nasal,IN),(77.56±17.22) μm (temporal upper,TU),(76.78±10.34) μm (temporal lower,TL),(88.94± 42.54) μm (nasal upper,NU),and (82.33±43.83) μm (nasal lower,NL) respectively,which was thinner than normal control group and physiologic large cup group,but thicker than POAG patients.Compared to normal controls and physiologic large cup patients,PPG patients also had 4 parameters reduced (RV,NHV,ODA and RA),and 5 parameters increased (CV,CDAR,VCDR,HCDR and CA),the differences are statistically significant (P＜0.05).However,these parameters were similar to POAG patients (P＞ 0.05).For macular GCC parameters,PPG patients also had 3 parameters reduced (average GCC,superior and inferior GCC thickness),and 2 parameters increased (GLV and FLV) compared to normal control group and physiologic large cup patients (P＜0.05).However,these parameters were similar to POAG patients (P＞0.05).Simple linear regression analysis showed that,with the GCC macular thinning,reducing the number of ganglion cells reduced,optic disc RNFL thickness became thinner (regression coefficient=1.25,P=0.00) and RV reduced (regression coefficient =0.037,P =0.00).Conclusions PPG patients and normal control had a similar distribution of optic disc RNFL.Five parameters (RV,NHV,ODA,RA,macular GCC thickness) were less than normal control and physiological big optic cup group,but had no significant differences compared with POAG group. Key words: Glaucoma/diagnosis; Retinal ganglion cells; Macula lutea; Optic disk; Tomography, optical coherence

The Effect of Pattern Scan Laser Photocoagulation on Peripapillary Retinal Nerve Fiber Layer Thickness and Optic Nerve Morphology in Diabetic Retinopathy

PurposeTo evaluate the effect of pattern scan laser (PASCAL) photocoagulation on peripapillary retinal nerve fiber layer (RNFL) thickness, central macular thickness (CMT), and optic nerve morphology in patients with diabetic retinopathy.MethodsSubjects included 35 eyes for the PASCAL group and 49 eyes for a control group. Peripapillary RNFL thickness, cup-disc area ratio and CMT were measured before PASCAL photocoagulation and at 2 and 6 months after PASCAL photocoagulation in the PASCAL or control groups.ResultsThe average RNFL thickness had increased by 0.84 µm two months after and decreased by 0.4 µm six months after PASCAL photocoagulation compared to baseline, but these changes were not significant (p = 0.83, 0.39). The cup-disc area ratio was unchanged after PASCAL photocoagulation. CMT increased by 18.11 µm (p = 0.048) at two months compared to baseline thickness, and partially recovered to 11.82 µm (p = 0.11) at six months in the PASCAL group.ConclusionsPASCAL photocoagulation may not cause significant change in the peripapillary RNFL thickness, CMT, and optic nerve morphology in patients with diabetic retinopathy.

A Comparison of Optic Nerve Head Topographic Measurements by Stratus OCT in Patients With Macrodiscs and Normal-sized Healthy Discs

To evaluate and compare optic nerve head parameters and retinal nerve fiber layer (RNFL) thickness between large discs and normal-sized vital discs using Stratus optical coherence tomography (OCT). A total of 293 healthy eyes (145 with macrodisc and 148 with normal-sized disc) were enrolled in the study. After a complete ophthalmic evaluation, measurement of optic nerve head parameters and RNFL thickness using OCT was performed in all subjects. Optic disc areas larger than 2.80 mm were accepted as macrodiscs. All OCT parameters were compared between normal-sized discs and macrodiscs. Participants' mean age was 46.5±10.6 years (range, 13 to 74 y). Average optic disc areas were 2.19±0.29 and 3.02±0.29 mm in the normal and the macrodisc groups, respectively. The optic disc area (P<0.0001), the cup area (P<0.0001), the horizontal cup disc ratio (P<0.0001), the vertical cup disc ratio (P<0.0001), and the cup disc area ratio (P<0.0001) were found to be significantly different in the macrodisc group and the control group. Rim areas (P=0.57) and RNFL thicknesses (inferior, superior, and mean) were found to be similar in both groups (P=0.75, 0.65, 0.85, respectively). A macrodisc may have a macrocup and should not be misdiagnosed as glaucoma. The present study showed that macrodiscs are identical to normal-sized discs in terms of rim area and RNFL thickness. We suggest that these 2 OCT parameters can help to differentiate a healthy macrodisc from a glaucomatous optic disc.

RetCam image analysis of the optic disc in premature infants

To evaluate the correlation between optic disc parameters and birth weight or gestational age in premature infants. RetCam fundal images were taken of 97 premature infants who needed screening for retinopathy of prematurity and who had no ischemic brain injury. The images were taken at a postmenstrual age of 36 weeks and analyzed. The optic disc cup to disc ratio, optic disc area, rim area, and cup to disc area ratio were calculated using image analysis. We evaluated the relationship between these optic disc parameters and gestational age or birth weight. The optic cup to disc ratio was less than 0.15 in 139 eyes (71.6%) and 0.5 or more in six eyes (3.1%). The optic cup disc area ratio was less than 0.05 in 146 eyes (75.3%) and 0.3 or more in four eyes (2.1%). On evaluating the association between optic disc parameters and gestational age or birth weight, optic disc cup to disc ratio, optic disc area, rim area, and cup to disc area ratio did not show significant relationships. The optic disc parameters of premature infants had no correlation with birth weight and gestational age.

Branch retinal vein occlusion and optic nerve head topographic parameters: the Singapore Indian eye study

AimTo examine the association between branch retinal vein occlusion (BRVO) and quantitative optic disc topographic parameters.MethodsThe Singapore Indian Eye Study (SINDI) is a population-based study of 3400 Singapore Indians aged...

Location of visual field defect and optic disc assessment by confocal scanning laser ophthalmoscope in early normal tension glaucoma

AbstractPurpose To compare topographic optic disc measurements in patients with central 10‐degree and outer arcuate visual field (VF) defects in early normal tension glaucoma (NTG)Methods Early NTG patients with a mean deviation of ‐10 dB or better in 24‐2 Humphrey VF analyzer, and glaucomatous optic disc were included in this retrospective study. Patients were divided into central VF defect group (CFD) with VF defect in 10‐degree radius in total deviation plot and peripheral VF defect group (PFD) with outer arcuate VF defect. Global and sectoral optic disc stereometric parameters were obtained with the Heidelberg Retina Tomograph (HRT) III and compared between CFD and PFD group. Mean deviation (MD) of central and nasal peripheral 12 points in mean deviation plot compared between superior and inferior hemifields in both groups.Results Mean deviation and pattern standard deviation values showed no significant difference between 27 patients in the CFD group and 29 patients in the PFD group. The cup area, cup disc area ratio was significantly decreased in CFD group compared to PFD group only in inferotemporal sector, not in other sectoral parameters and global parameters of HRT. The MD of VF in the CFD group was significantly decreased in superior central 6 points (‐9.23±8.12 dB) compared to inferior central 6 points (‐3.36±4.18 dB). The MD of VF in the PFD group showed no significant difference between superior (‐5.24±6.06 dB) and inferior (‐8.10±6.42 dB) nasal peripheral 6 points.Conclusion The change of optic disc in early NTG was more localized in the CFD group than the PFD group and central VF defect was more prominent in the superior hemifield.

Optic disc assessment using confocal scanning laser ophthalmoscope in normal tension glaucoma with disc hemorrhage

AbstractPurpose To evaluate which optic disc parameters have a relationship with the presence and the location of disc hemorrhages in normal tension glaucoma (NTG)Methods This retrospective study included patients with early NTG with mean deviation with – 10 dB or better in 24‐2 Humphrey visual field analyzer. Eyes in the whole study group were divided into those with and without disc hemorrhage. Optic disc stereometric parameters measured using the Heidelberg Retina Tomograph (HRT) III were compared between each group with and without disc hemorrhage. Within the group with disc hemorrhage, the location of disc hemorrhage was analyzed. Sectoral disc parameters were compared between two common locations where disc hemorrhage developed.Results Forty‐three patients with disc hemorrhage and 46 patients without disc hemorrhage were included in this study. Mean deviation and pattern standard deviation showed no significant difference between two groups. There was no significant difference in global optic disc parameters of HRT between two groups. Disc hemorrhage was displayed mainly in inferotemporal (23 eyes, 53.5%) and in superotemporal (12 eyes, 27.9 %). Regarding to sectoral disc analysis of inferotemporal quadrant, the value of cup shape measure and cup disc area ratio was higher in the disc hemorrhage group compared to the group without disc hemorrhage (P=0.0013, P=0.013, repectively). The subset analysis of disc parameters within the disc hemorrhage group, showed that superotemporal maximum cup depth in eyes with superotemporal disc hemorrhage was greater compared to inferotemporal maximum cup depth in eyes with inferotemporal disc hemorrhage (P=0.017).Conclusion The change of optic disc parameters in early NTG patients with disc hemorrha Commercial interest

Correlation of Frequency-doubling Perimetry With Retinal Nerve Fiber Layer Thickness and Optic Disc Size in Ocular Hypertensives and Glaucoma Suspects

To determine the structure-function correlation using frequency-doubling technology (FDT) perimetry and optical coherence tomography (OCT) in glaucoma suspects, and analyze their relationship to optic disc size. Sixty eyes of 60 ocular hypertensive patients (OHT) and 54 eyes of 54 subjects with optic disc features suspicious of glaucoma (disc suspects) with normal visual fields on Standard Achromatic Perimetry were recruited. All subjects underwent FDT perimetry using the N-30 program, and the mean deviation (FDT-MD) and FDT-pattern SD were computed. Average and inferior retinal nerve fiber layer (RNFL) thickness and disc area were measured on Stratus OCT. Pearson correlation coefficient was calculated among all the measurements. In disc suspects, FDT-MD correlated significantly with RNFL thickness measurements (P<0.001; P=0.003) and disc area (P<0.001). There was no correlation with the vertical cup-disc area ratio (VCDR) and FDT indices. In OHT, FDT-MD correlated significantly with average RNFL thickness (P=0.038), and there was a significant negative correlation between FDT-MD and the VCDR (0.042). The FDT-pattern SD negatively correlated with RNFL thickness measurements (P=0.008; P=0.03). The disc area correlated significantly with the average and inferior average RNFL thickness measurements in both groups of patients (P=0.029 and P=0.007; P=0.013 and P=0.013, respectively). In OHT, optic discs with larger VCDR and thinner RNFL had lower FDT-MD values. In disc suspects, smaller-sized discs had thinner RNFL and lower values of FDT-MD. FDT perimetry and OCT seem to be useful adjuncts to detect these eyes, which might warrant close follow-up to eventually detect glaucoma by Standard Achromatic Perimetry.

Comparing Stereometric Parameters Between Heidelberg Retinal Tomography 2 and 3 in Asian Eyes

To examine the correlation and agreement of stereometric parameters between Heidelberg Retinal Tomograph version 2 (HRT-2) and HRT-3 in a normal Asian population. This was a population-based study using data from the Singapore Malay Eye Study. Participants underwent a standardized and complete ophthalmic examination. A confocal laser ophthalmoscope using HRT-2 was used to take retinal images by 2 trained operators. Disc contours were drawn by a single experienced ophthalmologist. Without modifying the contours, the exact images were then exported and analyzed with HRT-3 software. Paired t tests were used to compare mean differences, whereas interclass correlations and Bland-Altman plots were used to assess agreement and trend of Moorfields regression analysis parameters between HRT-2 and HRT-3. A total of 2960 Malay participants [mean age, 58.3 y (SD 10.9); 50.5% female] were included. Average disc size was 2.15 μm. Interclass correlations and Bland-Altman plots showed good agreement between HRT-2 and HRT-3. However, global disc area, rim area, cup area, cup-disc area ratio, rim-disc area ratio, and rim volume were significantly different between HRT-2 and HRT-3, with all area and rim volume measurements using HRT-2 were approximately 4% larger compared with HRT-3. Analysis of HRT-2 and HRT-3 parameters from different sectors of the scans showed an inconsistent change in measurement values. Cup shape measurement was significantly different in the temporal region compared with the nasal region of the optic nerve head. There was good correlation between the 2 HRT versions and conversion equations were possible to calibrate HRT-3 parameters from HRT-2 measurements in Asian eyes. However, HRT-2 and HRT-3 showed significant differences in stereometric parameters. Further studies are needed to determine the impact of such differences and in comparative accuracy of HRT-2 versus HRT-3 for diagnosis and monitoring of glaucoma.

Optic disc topography in normal Indian eyes using spectral domain optical coherence tomography

Purpose:The aim was to study optic nerve head (ONH) parameters in normal Indian eyes using spectral domain optical coherence tomography (OCT)/scanning laser ophthamoscope (SLO).Materials and Methods:One hundred and fifty-seven eyes of 157 normal subjects of various age groups underwent ONH imaging with spectral OCT/SLO and the parameters obtained were correlated with disc size. The effect of age, gender, and refractive error on various ONH parameters were also studied.Results:The mean optic disc area was 3.36 ± 0.64 mm2 (range, 2.13–5.08 mm2), mean rim area was 2.49 ± 0.58 mm2 (range, 1.20–3.62 mm2), and mean cup area was 1.10 ± 0.75 mm2 (range, 0–3.07 mm2). The disc area showed significant positive correlation with the rim area, cup area, horizontal cup disc ratio, vertical cup disc ratio, cup disc area ratio, mean cup depth, and maximum cup depth (P < 0.001). Neither gender nor refractive error showed any significant difference in various ONH parameters. ONH parameters did not show significant change with age except for rim area which declined with the advancing age (r = –0.25, P < 0.001).Conclusions:The quantitative measurement of ONH topography obtained with this study provides a normative database for an Indian population with spectral OCT/SLO. As optic disc area influences ONH topography, disc size should to be considered when evaluating optic disc for progressive optic neuropathies such as glaucoma.

Electrophysiological Evidence of Early Functional Damage in Glaucoma and Ocular Hypertension

The quantification of early retinal ganglion cell damage in ocular hypertension and glaucoma. Thirty subjects under treatment for open-angle glaucoma, 23 subjects with ocular hypertension, and 28 healthy subjects in a control group were investigated by monocular pattern electroretinogram (ERG), L&M (long and medium wavelength) cone ERG, and S (short wavelength)-cone ERG. The diagnosis of glaucoma was based on masked assessment of digital stereoscopic optic nerve head images by three glaucoma specialists. The optic nerve head and retinal nerve fiber layer was assessed by scanning laser ophthalmoscopy and optical coherence tomography. All types of ERG had reduced mean amplitudes in ocular hypertension and open-angle glaucoma groups compared with the control group. In the ocular hypertension group, the N95 and the L&M-pathway photopic negative response (PhNR) were significantly attenuated (by 19% and 18% compared with the control group, respectively; by 30% and 22%, respectively, in the open-angle glaucoma group compared with the control group). In the subjects with open-angle glaucoma, the pattern ERG P50-N95 was found to be the most sensitive electrophysiological test, and the cup-disc area ratio, when examined by scanning laser ophthalmoscopy, was the most sensitive imaging parameter. Modest but not statistically significant correlations were found between the imaging and electrophysiologic parameters. With disc appearance used for the classification of open-angle glaucoma and ocular hypertension, significant electrophysiological losses were found in both conditions. The modest correlation between the structural and electrophysiological measures suggests that these assess different aspects of the pathologic process; electrophysiology can be used to quantify retinal ganglion cell dysfunction that occurs before cell death.

Vergleich papillenspezifischer Parameter einer europäischen und einer Bantu-Population

Glaucoma is the main cause of irreversible blindness in the world. Because of the increasing mean age, glaucoma is expected to become more common in the developing countries. Besides tonometry and perimetry the appearance of the optic nerve head is a main part of glaucoma diagnosis. Ethnic differences have to be considered. This study compares the appearance of the optic nerve head between blacks and whites. This is a retrospective analysis of 225 whites of a Swiss population and 1027 blacks of a Congolese population. Using a matched pairs technique 207 whites and 207 blacks were chosen, regarding age, sex, intraocular pressure and examined eye (right/left). The analysis of the optic nerve head was performed by using the "Heidelberg-Retina-Tomograph II" (HRT). Among the 207 persons of both groups we found 116 females and 91 males. There were 103 right eyes and 104 left eyes examined. The mean age was 45.6 +/- 15.6 years. Compared with European population in the African population we found a greater disc area (2.56 vs. 1.81 mm(2)) as well as a greater cup area (0.65 vs. 0.41 mm(2)) and a greater rim area (1.91 vs. 1.40 mm(2)). Regarding the cup disc area ratio there was no significant difference between both populations found (Kinshasa: 0.24 vs. Basel: 0.21). Although there was no significant difference of the maximum cup depth of both groups we found a deeper mean cup depth in the African population. Furthermore, we found differences regarding the cup shape measure, the RNFL thickness and the height variation contour. As already described in different studies, there are significant differences in the morphology of the optic nerve head between blacks and whites. Although blacks are expected to have a greater cup disc area ratio, this fact could not be proved in this study. As a new fact we found a different mean cup depth between Africans and Europeans, which might be explained by the different cup shape of both populations.

Agreement between Slit Lamp Examination and Optical Coherence Tomography in Estimating Cup-Disc Ratios

To compare optical coherence tomography (OCT) cup-disc ratio measurements with those estimated by two independent examiners using the slit lamp in an evaluation of the optic nerve head (ONH). In 47 eyes each of 47 patients with glaucoma and 47 healthy subjects, the ONH was examined using the slit lamp with a 78 D lens. Two examiners subjectively determined the cup-disc area ratio (A-CDR), the horizontal cup-disc ratio (H-CDR), and the vertical cup-disc ratio (V-CDR). These measurements were compared to objective OCT readings obtained by a third examiner blind to the slit lamp results. For the three variables determined, correlation indices between the OCT readings and the two sets of slit lamp measurements were significantly higher for the glaucoma group than the control group. In the patients with glaucoma, the OCT tended to underestimate A-CDR and overestimate H-CDR. For both these variables, Bland-Altmann analysis revealed significant differences between the two methods that persisted across the whole range of CDRs examined. In contrast, differences in V-CDR varied with disc size. The OCT is a diagnostic tool that provides a complete automatic evaluation of the ONH. However, its measurements vary significantly from those obtained in subjective evaluations performed by experienced ophthalmologists.

Heritability of Optic Disc and Cup Measured by the Heidelberg Retinal Tomography in Chinese: The Guangzhou Twin Eye Study

To assess the heritability of disc area (DA), cup area (CA), and cup-disc area ratio (CDAR) as intermediate phenotypes for glaucoma in Chinese subjects in a classic twin study. Twins (n = 1160) aged 7 to 15 years were identified in the Guangzhou Twin Registry. Optic disc parameters were measured with a Heidelberg Retina Tomograph (HRT; Heidelberg Engineering GmbH, Heidelberg, Germany) by the same examiner and grader. Zygosity was confirmed by genotyping with 16 polymorphic markers in all same-sex twin pairs. The DA, CA, and CDAR of the right eyes were chosen as the traits of interest in the analysis. Heritability was assessed by structural variance component genetic modeling, with Mx quantitative genetic modeling software, after adjustment for age and gender. Of those recruited, 1114 twins were identified in the analysis, including 355 monozygotic (MZ) and 202 dizygotic (DZ) twin pairs. The intraclass correlation coefficients were 0.79 for DA, 0.83 for CA, and 0.80 for CDAR in MZ pairs and 0.30, 0.37, and 0.35, respectively, in DZ pairs. The age- and sex-adjusted variance component model identified additive genetic and unshared environmental effects (AE model) being best fit for DA, CA, and CDAR. This best-fitting model yielded 77.3% additive genetic (95%CI: 73.0%-80.8%) and 22.7% unshared environment (95% CI: 19.2%-27.0%) for DA, 82.7% (95% CI:79.4%-85.5%) and 17.3% (95% CI: 14.5%-20.6%) for CA, 78.6% (95% CI: 74.5%-82.0%) and 21.4% (95% CI: 18.0%-25.4%) for CDAR. The variance of optic nerve head parameters (DA, CA, and CDAR) appears to be attributable to additive genetic and unshared environmental effects. Approximately 80% of these phenotypic variances are genetically determined.