Disc Rim Area Research Articles

Optic Nerve Hypoplasia With Isolated Tortuosity of the Retinal Veins

To investigate whether children with optic nerve hypoplasia and pituitary hormone insufficiencies have specific ocular fundus characteristics that may facilitate early diagnosis and treatment. From May 15, 1995, through December 15, 1997, 17 children (8 girls and 9 boys, aged 0.3 to 13 years) with optic nerve hypoplasia were referred to the Department of Pediatric Ophthalmology, Children's Hospital, Göteborg, Sweden, and divided into 2 groups dependent on the presence (n = 8) or absence (n = 9) of pituitary deficiency. Morphological characteristics of the ocular fundus were evaluated by digital image analysis of fundus photographs, and the morphological characteristics of the brain structures were studied by magnetic resonance imaging. An isolated venous tortuosity noted among the children with optic nerve hypoplasia and endocrinopathy was the morphological ocular fundus variable that discriminated between the 2 groups of patients with optic nerve hypoplasia. Both groups of children demonstrated significantly reduced optic disc, cup, and neuroretinal rim area and few vascular branching points. Optic nerve hypoplasia with isolated tortuosity of the retinal veins may potentially help the ophthalmologist in identifying children who should undergo a thorough diagnostic workup of endocrine function.

Preperimetric glaucoma diagnosis by confocal scanning laser tomography of the optic disc

AIMTo evaluate the ability of confocal scanning laser tomography of the optic nerve head to detect glaucomatous optic nerve damage in ocular hypertensive eyes without visual field defects.METHODSThe study included...

Neuroretinal rim width ratios in morphological glaucoma diagnosis

AIMSTo evaluate the inferior to temporal neuroretinal rim width ratio and superior to temporal rim width ratio as measures of rim shape for diagnosis of glaucoma.METHODSColour stereo optic disc photographs...

Identification of early glaucoma cases with the scanning laser ophthalmoscope

Purpose This study aimed to define the confocal laser scanning ophthalmoscope (Heidelberg Retina Tomograph [HRT]) parameters that best separate patients with early glaucoma from normal subjects. Study design A cross-sectional study. Participants A total of 80 normal subjects and 51 patients with early glaucoma participated (average visual field mean deviation = −3.6 dB). Intervention Imaging of the optic nerve head with the HRT and analysis using software version 1.11 were performed. Main outcome measures The relation between neuroretinal rim area and optic disc area, and cup-disc area ratio and optic disc area, was defined by linear regression of data derived from the normal subjects. The normal ranges for these two parameters were defined by the 99% prediction intervals of the linear regression between the parameter and optic disc area, for the whole disc, and for each of the predefined segments. Normal subjects and patients were labeled as abnormal if the parameter for either the whole disc or any of the predefined segments was outside the normal range. The sensitivity and specificity values of the method were calculated. Results The highest specificity (96.3%) and sensitivity (84.3%) values to separate normal subjects and those patients with early glaucoma were obtained using the 99% prediction interval from the linear regression between the optic disc area and the log of the neuroretinal rim area. Similar specificity (97.5%) and lower sensitivity (74.5%) values were obtained with the 99% prediction interval derived from regression between the disc area and cup-disc area ratios. Poor separation between groups was obtained with the other parameters. Conclusions The HRT, using the technique of linear regression to account for the relationship between optic disc size and rim area or cup-disc area ratio, provides good separation between control subjects and patients with early glaucoma in this population.

Aging changes of the optic nerve head in relation to open angle glaucoma

AIMSTo determine the age related changes in optic nerve head structure in a group of normal subjects and assess the significance of any changes in relation to those found in...

Comparison of Methods to Evaluate the Optic Nerve Head and Nerve Fiber Layer for Glaucomatous Change

To compare the rates of optic nerve damage in early human glaucoma as measured by four methods to evaluate change in the optic nerve and nerve fiber layer. Four techniques were used to detect progressive glaucomatous damage in a prospective, longitudinal study: (1) qualitative evaluation of stereoscopic color optic disk photographs, (2) qualitative evaluation of monochromatic nerve fiber layer photographs, (3) manual stereoplanimetric measurements of disk rim area, and (4) computerized measurement of peripapillary nerve fiber layer height. One eye of each patient with glaucoma or ocular hypertension was evaluated at the beginning and end of a follow-up period of not less than one year. The rates of structural change measured by these techniques and the rate of visual field change measured with threshold automated perimetry were determined. We followed up 193 patients for a mean (+/- S.D.) of 3.3 +/- 1.0 years (range, one to six years). Twenty-nine (15%) of 193 eyes progressed by qualitative optic disk evaluation, 14 (7.2%) of 193 eyes progressed by qualitative nerve fiber layer evaluation, seven (3.6%) of 193 eyes progressed by stereoplanimetry, and 24 (13.2%) of 182 eyes progressed by measurement of nerve fiber layer height. Visual field deterioration was detected in 12 (5.2%) of 193 patients and correlated best with qualitative optic disk and nerve fiber layer evaluations. Evaluation by stereoplanimetry and nerve fiber layer height measurement detected change in eyes with primarily diffuse structural damage, a pattern not well detected by qualitative methods. Both qualitative and quantitative methods of optic disk and nerve fiber layer evaluation contribute to the identification of progressive damage, depending on the stage of disease and the characteristics of optic nerve cupping.

Ethnic Differences in Optic Nerve Head Topography

To investigate ethnic differences in optic nerve head topography. This is a cross-sectional university-based comparative study of 180 normal subjects (43 African-American, 45 Asian, 48 Hispanic, and 44 white subjects) ages 19-40 years. Optic nerve head parameters including optic disc size, cup-disc ratio, rim area, rim volume, cup volume, and maximal cup depth were measured using a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). Differences among groups were evaluated using analysis of variance. Disc area, cup volume, maximal cup depth, and vertical cup-disc ratio were largest in African-Americans, intermediate in Asians and Hispanics, and smallest in whites; for these parameters the differences between African-Americans and whites were statistically significant. Significant differences were also found between African-Americans and Hispanics for cup volume, and between African-Americans and Asians for vertical cup-disc ratio and maximal cup depth. Rim volume and rim area were not significantly different among the four ethnic groups. Ethnic differences in the normal optic nerve are present and should be taken into a ccount when evaluating the optic disc for glaucoma and other optic neuropathies.

Correlation of Peripapillary Retinal Height and Visual Field in Glaucoma and Normal Subjects

To investigate the relationship between peripapillary retinal height and visual field sensitivity. Fourteen normal subjects and 25 primary open-angle glaucoma patients were examined using a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). Visual fields (Humphrey program 24-2) were assessed with both standard achromatic automated perimetry and shortwavelength automated perimetry. The mean peripapillary retinal height was determined for superotemporal (60-90 degrees ), superonasal (91-120 degrees ), inferotemporal (271-300 degrees ), and inferonasal (240-270 degrees ) sectors. Based on Glaucoma Hemifield Test sector definitions, achromatic automated perimetry and short-wavelength automated perimetry fields were divided into each of four distinct regions. Significant differences in disc rim area, rim-disc area ratio, cup volume, and each papillary region were found between glaucoma patients and normal subjects. With both standard achromatic automated perimetry and short-wavelength automated perimetry, significant correlations (p < 0.05) were found between the mean peripapillary retinal height of the inferotemporal, inferonasal, superotemporal, and superonasal sectors and age-adjusted mean deviation of their respective anatomically matched visual field region. In addition, peripapillary retinal height was more highly correlated with ageadjusted mean deviation than disc rim area in glaucoma patients. We found that peripapillary height, particularly in the temporal region, showed the strongest association with visual field loss in glaucoma patients.

Comparisons of Methods To Detect Glaucomatous Optic Nerve Damage

Various techniques of optic disc and nerve fiber layer evaluation may be used to detect structural glaucomatous damage. The authors compared several qualitative and quantitative methods to determine their relative sensitivities and specificities to detect the presence of glaucomatous visual field loss. Fifty-one healthy eyes, 169 ocular hypertensive eyes with normal visual fields, and 132 glaucomatous eyes with early visual field defects were evaluated with qualitative and quantitative measures of structural damage to the optic nerve and nerve fiber layer. Qualitative evaluations were performed by three experienced masked observers who independently graded stereoscopic color disc and monochromatic nerve fiber layer photographs. Quantitative measurements of disc rim area and nerve fiber layer height were made with digitized image analysis of videographic images. Manual planimetric measurements of disc rim area were made from enlarged prints of stereoscopic optic disc photographs. Diagnostic precision was defined as the total proportion of correct diagnoses for the presence or absence of visual field loss. The diagnostic precision of results of a quantitative disc examination (81%) was greater than those of a qualitative nerve fiber layer examination (75%). Quantitative nerve fiber height measurement had the highest sensitivity rate (73%) and results of the qualitative disc examination had the highest specificity rate (87%) of the methods tested. The diagnostic precision of disc evaluation was superior to other methods, including nerve fiber layer examination, in correctly determining the presence of structural glaucomatous damage at the early visual field loss stage.

Clinical Disc Biometry in Early Glaucoma

To assess the potential of a clinical method of optic disc measurement in the detection of early neuroretinal rim loss in glaucoma. A method of disc biometry based on indirect ophthalmoscopy was used to estimate disc and neuroretinal rim areas in 81 ocular hypertensive eyes of 43 patients and in 28 fellow eyes with normal visual fields of patients with unilateral visual field loss from primary open-angle glaucoma. The results were compared with those from age-matched visually normal patients. Neuroretinal rim area was significantly smaller in both hypertensive and fellow eye groups compared with controls (P < 0.0001; P = 0.0009). Disc area also was smaller in both groups (P = 0.0034; P = 0.046); however, this was inadequate to explain the differences in rim area, which, when corrected for disc size, were still highly significant (P < 0.0001; P = 0.0001). The differences in neuroretinal rim area observed are likely to indicate that a proportion of the eyes studied had suffered a reduction of neuroretinal rim area, which was measurable by this method at a stage before the development of demonstrable visual field loss.

Digital image analysis of optic nerve head pallor as a diagnostic test for early glaucoma.

We developed a computer-based technique to quantify optic nerve head pallor from videographically acquired digitized optic nerve images and tested the ability of pallor measurements to discriminate between normal eyes and eyes with early glaucoma. Corresponding pixel values from images obtained under 540 nm (green) and 640 nm (red) light with a videographic fundus camera were used to quantify optic nerve head pallor. A pallor density histogram was calculated for each eye, and contained values between 0 (red) to 1 (white). A measure of the distribution width of the histogram provided pallor measurements standardized to the measurements of the large veins of the disc. A database of one eye each of 44 normal controls and 70 patients with early open angle glaucoma was used to test the measurements for diagnostic sensitivity and specificity. These standardized pallor measurements did not perform better than absolute pallor measurements to discriminate between normal and glaucomatous eyes. The sensitivity and specificity of standardized pallor measurements (49% and 57%, respectively, for this database) were not as good as those for stereoscopic measurements of disc rim area in the same database (70% and 73%). Pallor measurements of this type do not appear to be sensitive or specific indicators of early glaucoma.

Age-related Decline of Disc Rim Area in Visually Normal Subjects

Optic disc parameters and axial lengths were measured in 81 visually normal young and elderly white adults (young [n = 41]: 27.2 +/- 5.7 years versus elderly [n = 40]: 68.8 +/- 8.4 years) using Rodenstock Optic Disc Analyzer and A-scan sonography. Axial lengths correlated positively with optic disc parameters (Spearman correlation analysis: rim area: P = 0.042, disc area: P = 0.052, and cup volume: P = 0.010). Older subjects had a shorter axial length (23.09 +/- 1.02 mm) and smaller disc rim area (1.171 +/- 0.338 mm2) than younger subjects (23.60 +/- 1.15 mm and 1.325 +/- 0.314 mm2; Mann-Whitney U test: P = 0.011 and P = 0.013, respectively). While both axial length and disc rim area declined with age (0.011 mm and 0.003 mm2 per year; Spearman correlation analysis: P = 0.032 and P = 0.020, respectively), the cup-to-disc and rim area-to-disc area ratios appeared to remain relatively constant throughout adult life. The age-related decline of disc rim area is consistent with histologic evidence of age-related decline of ganglion cell axons. The rim area-to-disc area ratio seems less affected by age, and is thus a better parameter to isolate age-related change from disease-related change of optic nerve in a longitudinal follow-up of diseases involving the optic nerve head.

Disc and field damage in patients with unilateral visual field loss from primary open-angle glaucoma.

To assess the temporal relationship between field and disc change in early glaucoma, 24 patients with unilateral visual field loss from primary open angle glaucoma were identified for planimetric optic disc measurements. Cross-sectional analysis of disc rim area was performed and compared to 25 age-matched normal controls. The mean (+/- SD) disc rim area in eyes with normal visual fields (1.10 +/- 0.31 mm2) was slightly larger than that of eyes with visual field loss (0.90 +/- 0.33 mm2). The mean disc rim area in the control group (1.49 +/- 0.19 mm2) was significantly different from both sets of eyes in the asymmetric primary open angle glaucoma patients (p = 0.000). These findings support the hypothesis that loss of the optic disc rim can be detected before perimetric abnormalities develop in patients with glaucoma.

Optic Nerve Head and Nerve Fiber Layer in Alzheimer's Disease

We compared (1) the differences in the retinal nerve fiber layer between 26 patients with Alzheimer's disease and 30 age- and race-matched normal controls with use of blue-light high-resolution photography, (2) the differences in disc pallor between 30 patients with Alzheimer's disease and 32 controls with use of a boundary-tracking program and fundus photographs, and (3) the topographic disc variables between 26 patients with Alzheimer's disease and 36 controls with use of an optic nerve head analyzer. A higher proportion of patients with Alzheimer's disease had detectable nerve fiber damage as seen by red-free photography compared with controls. Although the pallor area-to-disc area ratio was not significantly different between patients with Alzheimer's disease and controls, the patients with higher pallor area-to-disc area ratios had higher Alzheimer's Disease Assessment Scale (ADAS) scores and longer durations of disease. Patients had an increased cup-to-disc ratio and cup volume and decreased disc rim area compared with controls. These variables also correlated significantly with ADAS scores and the duration of disease. The correlation among the optic nerve head changes and the ADAS scores in patients with Alzheimer's disease suggests a potential role for optic nerve head analysis in monitoring the progression of Alzheimer's disease and in assessing the effectiveness of any treatments developed.

Measurement of Optic Disc and Neuroretinal Rim Areas in Normal and Glaucomatous Eyes: A New Clinical Method

A technique based on indirect ophthalmoscopy has been devised to enable measurement of structures in the posterior pole of the eye. It has been used to measure clinically the maximal and minimal diameters of both the optic disc and cup of 130 normal eyes from 66 patients and 33 optic discs from 20 patients with glaucomatous visual field loss. The disc area and neuroretinal rim area were derived mathematically for each eye. In the normal group the neuroretinal rim area was strongly correlated with the disc area (r = 0.89, P < 0.0001). Only 9.1% of the glaucomatous group fell within the 95% prediction interval for the normal group, indicating a high degree of sensitivity and specificity for predicting the presence of visual field loss. Discs associated with mild field loss could be discriminated from those associated with moderate or severe field loss on the basis of disc and rim area measurements.

Optic Disc Topography in Patients With Low-Tension and Primary Open Angle Glaucoma

Computerized optic disc topographic measurements (cup-disc ratio, neuroretinal rim area, disc volume) and automated visual field parameters (total field loss, mean sensitivity) were similar in 48 eyes with primary open angle glaucoma and 27 eyes with low-tension glaucoma. In open angle glaucoma, the neuroretinal rim area was negatively correlated with the cup-disc ratio and the disc volume. Total field loss was positively correlated with the cup-disc ratio and the disc volume and negatively correlated with the neuroretinal rim area. Eyes with low-tension glaucoma showed a negative correlation between neuroretinal rim area and cup-disc ratio, and between total field loss and rim area. However, low-tension glaucomatous eyes did not have significant correlations between disc volume and rim area and between total field loss and cup-disc ratio or disc volume. Cupping in low-tension glaucoma was broadly sloping, resulting in less disc volume alteration.

The Contour of the Juxtapapillary Nerve Fiber Layer in Glaucoma

Reliable structural markers for early glaucomatous optic nerve damage would facilitate the diagnosis of glaucoma at an early stage, possibly before visual field loss occurs. Computerized image analyses were used to develop and analyze new structural parameters for glaucomatous optic nerve damage. Multiple measurements of relative juxtapapillary nerve fiber layer height were made in glaucoma patients (n =112), patients suspected of having glaucoma (n = 87), and in age-matched normal control subjects (n = 53). The average relative nerve fiber layer (NFL) height differed in glaucoma patients and normal subjects by 70 μm, but differences exceeded 100 μm at the superior and inferior poles of the disc. Mean values for “glaucoma suspects” were intermediate between those for the normal subjects and glaucoma groups. The ability of summary statistics of relative NFL height measurements to discriminate between normal and glaucomatous eyes was superior to that of the standard disc parameters cup-disc ratio, disc rim area, and cup volume. Measurements of relative NFL height correlated with indices of visual field loss; the strongest correlations occurred for measurements at the superior and inferior poles. Measurements of juxtapapillary NFL height may prove useful to detect glaucomatous optic nerve damage at an early stage and to accurately recognize progressive nerve damage over time.

A Comparative Evaluation of Three Methods of Analyzing Optic Disc Topography

Topographical evaluations of the optic discs of 17 eyes obtained using a clinical planimeter, the Rodenstock video-ophthalmograph, and the IS 2000 image analyzer were compared. The parameters studied were vertical and horizontal cup-to-disc ratios, cup volumes, rim areas, disc areas, and rim area-to-disc area ratios. There was good correlation between the measurements obtained by the three methods (correlation coefficients ranged from 0.46 to 0.88). For various parameters, the correlations between clinical planimetry and image analysis were higher than either those between image analysis and video-ophthalmography, or those between clinical planimetry and video-ophthalmography. The mean horizontal cup-to-disc ratios and rim areas as measured by clinical planimetry were significantly higher than those measured by image analysis. Image analysis measured significantly higher disc area and rim areas and lower cup volumes than video-ophthalmography.

Measurements of Peripapillary Nerve Fiber Layer Contour in Glaucoma

We developed a method to quantify the surface contour of the peripapillary nerve fiber layer from simultaneous stereoscopic videographic images. Parameters that describe this contour are defined and compared to standard optic nerve structural parameters (cup/disk ratio, disk rim area, cup volume) in three age-matched groups of patients: 52 normal controls, 79 glaucoma suspects, and 101 glaucoma patients. Greater discriminatory information was obtained from the measurements from the superior and inferior quadrants than from the measurements from the temporal and nasal quadrants. This approach helps identify new structural markers that may more closely reflect the number of ganglion cell axons in the optic nerve. Such measurements made longitudinally in living eyes will provide valuable information about the relative rates of ganglion cell death in aging and in glaucoma.

Reliability of Optic Nerve Head Topographic Measurements With Computerized Image Analysis

We evaluated the reliability of optic disk area and disk rim area measurements obtained with the Humphrey Retinal Analyzer from ten repeat fundus images each of one eye of ten normal subjects and ten subjects with increased intraocular pressure. Variability of rim and disk areas was not significantly different between these two groups (P greater than .05), nor was it significantly different between images acquired during the same session and those acquired during different sessions (P greater than .05). Variability was significantly different between subject groups based on the distinctness of the disk edge and the slope of the cup wall (P less than .01). The average minimum change in the measurements on the same eye that would exceed variability of the technique at the 95% confidence level was 0.20 mm2 and 0.47 mm2 for rim area for the least variable and most variable subject groups based on optic nerve head characteristics, and 0.09 mm2 and 0.32 mm2 for disk area for the corresponding subject groups. Operator input contributed significantly to overall variability. Reliability of rim and disk areas in this study was comparable to that reported for other computerized image analyzers.