Sensitivity and specificity of optic disc variables and analysis of a new variable (MP/D) for glaucoma diagnosis with the Glaucoma-Scope

AIM: In an attempt to use the quantitative optic disc measurements of the Glaucoma-Scope (OIS Sacramento, CA, USA) to distinguish glaucomatous from normal optic discs, a new variable was investigated, the mean disc corrected for the disc size by dividing by the disc area: MP/D. METHODS: Glaucoma-Scope disc evaluation was performed on 81 eyes of 51 patients split into the following groups based on Humphrey 24-2 visual field and clinical criteria of glaucoma: chronic glaucoma n = 27 (including only early, n = 17, and low tension glaucoma, n = 10), ocular hypertension n = 24, pseudoglaucomatous large discs, n = 12, and normal eyes, n = 18. Classic optic disc variables (the vertical and horizontal c/d ratios, and the c/d area) were compared with the new MP/D index calculating receiver operating characteristic curves. RESULTS: The MP/D ratio was able to identify the glaucomatous eyes more easily than other ratios. Areas under the curves were: 0.91 (MP/D); 0.87 (c/d area); 0.85 (c/d vertical); and 0.80 (c/d horizontal). The MP/D index was also correlated with the mean deviation (r = 0.466; p = 0.001). CONCLUSION: MP/D may prove useful in detecting glaucomatous optic nerve damage and could be an interesting screening tool for primary open angle glaucoma.     

Protracted posttraumatic optic disc swelling

BACKGROUND: Optic disc swelling is a rare sequela of blunt ocular trauma. METHODS: The authors examined three young patients who had an unusual post-traumatic optic neuropathy in which protracted swelling of the optic nerve head was the salient clinical feature. RESULTS: Associated choroidal ruptures in two patients suggested a contrecoup mechanism of injury to the optic nerve at its junction with the globe. All patients had partial recovery of vision over months, concurrent with resolution of the nerve head swelling and development of optic disc pallor. CONCLUSION: Despite its protracted course, posttraumatic optic disc swelling appears to be associated with a favorable prognosis for visual recovery.     

Ophthalmoscopic measurement of the optic disc

PURPOSE: The authors evaluated whether the optic disc dimensions can be measured directly by ophthalmoscopy without the use of a fundus camera or special ophthalmoscope. MATERIALS AND METHODS: The horizontal and vertical disc diameters were measured ophthalmoscopically in 158 eyes of 95 subjects using a standard Goldmann three-mirror contact lens and a commercial slit lamp with adjustable length of the beam. The refractive error ranged from -7.25 to 3.5 diopters. Based on these direct measurements, the authors calculated the disc area by applying a modified formula for an ellipse, where area = pi/4 x the horizontal diameter x the vertical diameter. Additionally, the authors determined by planimetry the diameters and area of the disc on color photographs after correcting the ocular and photographic magnification. RESULTS: The values of the disc diameters as determined by photography were x1.27 larger than those measured with the Goldmann contact lens. Taking into account this constant correction factor of 1.27 for all eyes examined, the disc diameters, as measured by the Goldmann lens, varied by 0.11 +/- 0.06 mm or 5.8% +/- 3.5% from the values measured on the photographs. This error decreased slightly (P = 0.04) with increasing disc size. It was independent of the refractive error. The calculated disc area based on the ophthalmoscopically determined disc diameters differed by 9.4% +/- 6.6% from the disc area as measured by planimetry on the photographs. CONCLUSIONS: For clinical purposes, the optic disc and other structures of the posterior fundus can be measured by ophthalmoscopy using a Goldmann contact lens and a slit lamp with adjustable beam length. The optic disc area can be calculated by the formula: horizontal disc diameter x vertical disc diameter x pi/4.     

Unilateral retinitis pigmentosa and pit of optic disc

A 59-year-old woman had an unusual association of unilateral retinitis pigmentosa and optic pit with macular pathologic features in the same eye. A general ophthalmic and electrophysiologic investigation characterized the patient's condition functionally, without defining the basic defect responsible for this peculiar association. While an exact explanation of this occurrence cannot be given at this time, the possibility of coincidence or abiotrophy with developmental defects can be suggested as its intimate mechanism.     

Asymmetry of retinitis pigmentosa-related to initial optic disc vasculitis

A case of highly asymmetric retinitis pigmentosa is reported. Signs of pigmentary retinopathy appeared in the first eye following optic disc vasculitis or neuroretinitis of unknown etiology. Within 2 years the visual field became markedly restricted and the dark adaptation thresholds elevated. Twelve years later this eye was almost blind and the ERG was non-recordable. In the fellow eye, the first pigmentary changes were observed 5 years after the initial presentation, and the progression was slow. Nineteen years after the initial examination the visual field of the less affected eye was constricted to 30 degrees nasally and 60 degrees temporally, the dark adaptation threshold was only slightly elevated, and the full-field ERG was within normal range. It is possible that neuroretinitis or vasculitis of the optic disc caused the earlier onset and the more progressive course of pigmentary retinopathy in the initially affected eye.     

Retinal ganglion cell layer and visual function in a patient with optic disc drusen

BACKGROUND: To correlate the retinal ganglion cell pattern to visual acuity and visual field data in a patient with bilateral optic disc drusen, a quantitative clinicopathological study was carried out. METHODS: Both retinae of a patient with optic drusen were whole-mounted. Retinal ganglion cell counts were made using a sampling scheme covering the whole retina and compared to the findings in 10 normal retinae. Relative ganglion cell reduction in the drusen retinae was correlated to clinical data. RESULTS: The total retinal ganglion cell count was reduced from 1244858+/-98736 in normal retinae to 305319 on the right and 527571 on the left eye with optic disc drusen. Large ganglion cells had a better chance of survival. Parafoveal ganglion cell loss was 57% for the right and 36% for the left eye, while visual acuity was 0.8 and 1.0 respectively. The mean light sensitivity loss increased from the centre (6.2 dB) to paracentral (9.9 dB), mid-peripheral (13.7 dB) and outer peripheral (15.0 dB) retina, while ganglion cell losses were smallest in outer peripheral retina (21.9%), followed by central (53.0%), mid-peripheral (70.9%) and paracentral retina (87.7%). CONCLUSION: These data validate Frisén's theory on central retinal resolution and provide the structural basis for the clinical rule that low visual acuity should not be attributed to disc drusen. Automated light sense perimetry gives an inadequate picture of retinal damage caused by optic disc drusen.     

Proliferative diabetic retinopathy with a proliferative membrane that spread anteriorly from the optic disc

The authors report a case of proliferative diabetic retinopathy in which the proliferating membrane spread from the optic disc to the anterior of the eyeball, and did not appear to involve the posterior precortical vitreous pocket.     

Influence of acquisition parameters on hemodynamic measurements with the Heidelberg Retina Flowmeter at the optic disc

Asymmetrical IgG molecules are characterised by the presence of a mannose-rich oligosaccharide group in only one of the two Fab fragments, which impairs the corresponding paratope, causing such molecules to behave as univalent antibodies and therefore as antigen blockers [1-3]. During human and murine pregnancy, an increase has been detected in asymmetrical IgG molecules in serum and those bound to the placenta, which normally releases factors capable of modulating the immune response. It thus seemed of interest to investigate the effect of placental culture supernatants (PCS) on in vivo and in vitro synthesis of rat immunoglobulin IgG1, IgG2a, IgG2b and IgG2C, particularly the ratio of symmetrical and asymmetrical molecules in each isotype. The effect of PCS was determined in vivo by means of passive transfer to virgin females and in vitro by analysing the supernatants of spleen cells cultured in the presence of PCS. The results showed that neither pregnancy status nor PCS were capable of modifying serum levels of IgG2a, IgG2b or IgG2c, whereas the level of IgG1 was reduced. When PCS were added to the spleen cells cultures, an in vitro increase was observed in IgG2a, IgG2b and IgG2c production. The separation of symmetrical from asymmetrical IgG molecules was performed by affinity chromatography in Concanavalin A-Sepharose, as such lectin binds high mannose sugars present only in asymmetrical IgG molecules. It is shown that pregnancy and PCS induce an increase in IgG1 and IgG2 molecules asymmetrically glycosylated, capable of binding to ConA-Sepharose. Therefore, the placenta is capable of releasing factors which can regulate the relative proportion of asymmetrical IgG molecules and induce quantitative and qualitative modifications of the in vitro and in vivo produced antibodies.     

Morphometry of the optic disc in Togolese patients with glaucoma or suspected glaucoma. Preliminary study

PURPOSE: The aim of this study was to measure morphometric parameters of the optic disc in Togolese glaucoma patients and suspects by the mean of the millimetric scale of the slit lamp and the Goldmann contact lens. MATERIAL AND METHOD: We selected 202 patients (393 eyes) with a mean age of 36.69 years +/- 15.33 (standard deviation); they were divided into 2 subgroups A (162 glaucomatous) and B (40 glaucoma suspects); direct reading of the slit lamp millimetric scale and the Goldmann contact lens was used. RESULTS: In the group A, the optic disc vertical diameter was 1.792 +/- 0.21 mm; the horizontal diameter was 1.701 +/- 0.198 mm. In the group B, vertical disc diameter was 1.700 +/- 0.262 mm; the horizontal one was 1.662 +/- 0.190 mm. The vertical cup disc diameter was 1.147 +/- 0.274 mm in the group A and 0.708 mm +/- 0.274 mm in the group B. The neuroretinal area was 1.360 +/- 0.524 mm2 in group A and 1.786 +/- 0.467 mm2 in group B. CONCLUSION: This study using millimetric scale of the slit lamp and the three mirrors Goldmann contact lens was easy, simple and useful clinically. It could be helpful in conducting quantitative studies in countries with low resources because this method is costless compared with others.     

Optic disc morphology in eyes after nonarteritic anterior ischemic optic neuropathy

PURPOSE: Parapapillary chorioretinal atrophy, neuroretinal rim loss, and a decrease of retinal vessel diameter have been described to occur in glaucomatous eyes. This study was conducted to evaluate the frequency and degree of these signs in nonarteritic anterior ischemic optic neuropathy (AION). METHODS: We evaluated morphometrically and compared stereo color optic disc photographs of 17 patients after AION, 184 patients with primary open-angle glaucoma, and 98 normal subjects. RESULTS: The optic disc area and retinal vessel diameter were significantly smaller and the visibility of the retinal nerve fiber bundles was significantly reduced in patients after nonarteritic AION compared with that of the normal subjects. The optic disc shape, area, and form of zones alpha and beta of the parapapillary chorioretinal atrophy and the size and form of the neuroretinal rim did not differ significantly between these two groups. In the group of eyes with glaucoma, the neuroretinal rim was significantly smaller and the parapapillary chorioretinal atrophy was significantly larger than in the group of eyes with AION. Visibility of the retinal nerve fiber bundles and retinal vessel caliber did not differ statistically between the eyes with AION and those with glaucoma. CONCLUSIONS: These results indicate that the parapapillary chorioretinal atrophy is not larger in eyes after nonarteritic AION compared with normal eyes. They show that the area and shape of the neuroretinal rim, as determined planimetrically, may not markedly change after nonarteritic AION. They confirm previous reports on a small optic disc size as a risk factor for nonarteritic AION. They agree with findings of a reduced retinal vessel caliber in eyes with optic nerve damage, independently of the cause.     

The relationship between deterioration and reversal of optic disc cupping in monkeys with chronic experimental high-pressure glaucoma

PURPOSE: To investigate the correlation between the deterioration in optic disc cupping during the chronic elevation of intraocular pressure (IOP) and the reversal of cupping during a subsequent reduction in IOP in experimental glaucoma. METHODS: We examined changes in the vertical and horizontal cup to disc ratios, the rim area to disc area ratio, and the cup volume to disc area ratio in 11 monkey eyes with laser-induced glaucoma using computerized stereo-image analysis. Correlations between changes in disc parameters during a spontaneous IOP reduction and changes in disc parameters during a period of chronic IOP elevation from baseline before laser exposure (baseline) to before the IOP reduction (pre-IOP reduction) and during the period from baseline to after the reduction in IOP (post-IOP reduction) were determined by linear regression analysis. RESULTS: All disc parameters improved significantly during IOP reduction and deteriorated significantly during the periods from baseline to the pre-IOP reduction and from baseline to the post-IOP reduction. The degree of reversal in disc parameters was correlated with the deterioration from baseline to the pre-IOP reduction and from baseline to the post-IOP reduction in the vertical cup to disc ratio (r = 0.68, P = 0.0218 and r = 0.97, P < 0.0001, respectively), the horizontal cup to disc ratio (r = 0.57, P = 0.0649 and r = 0.98, P < 0.0001, respectively), the rim area to disc area ratio (r = 0.68, P = 0.0227 and r = 0.98, P < 0.0001, respectively), and the cup volume to disc area ratio (r = 0.67, P = 0.0256 and r = 0.88, P = 0.0004, respectively). CONCLUSION: The degree of deterioration in cupping from baseline before the induction of glaucoma may be an important determinant of the degree of cupping reversal during subsequent reductions in IOP in primate glaucoma.     

Influence of optic disc size on the sensitivity of the Heidelberg Retina Tomograph

PURPOSE: The aim of this study was to evaluate the influence of optic disc size on the ability of variables generated by the Heidelberg Retina Tomograph, software version 1.11, to distinguish glaucoma patients from normals in a cross-sectional study. PATIENTS AND METHODS: For evaluation of the optic disc with the Heidelberg Retina Tomograph, eyes of 87 normals and 61 glaucoma patients were selected. Disc area, volume above reference, rim area, cup area, cup volume, third moment in contour and the mean retinal nerve fibre layer thickness at the border of the optic disc were selected for evaluation. The sensitivity at 80% specificity of these variables was calculated under three conditions: (1) no correction for disc size; (2) calculation in the following disc size ranges: class I (1.0-2.0 mm2), class II (2.0-2.5 mm2), class III (2.5-3.15 mm2) and class IV (3.15-5.0 mm2); (3) calculation globally, taking into account the different disc sizes of the four classes. RESULTS: Neuroretinal rim area, cup area and volume, third moment and nerve fibre layer thickness were significantly and positively correlated with optic disc size in normals. Neuroretinal rim volume measurements were statistically independent of optic disc size. Sensitivity was lowest when the size of the optic disc was not considered. Sensitivity increased when evaluated in four optic disc size classes. With growing optic disc size sensitivity of the retinal nerve fibre layer increased and third moment value decreased. Cup volume and area had their lowest sensitivity for large optic discs. The area of the neuroretinal rim was the only variable which showed similar sensitivity values under all three conditions. CONCLUSIONS: The sensitivities of HRT variables varied with optic disc size. Evaluation of their sensitivity requires the definition of optic disc classes or statistical correction for the size of the optic disc.     

Registration of neural maps through value-dependent learning: modeling the alignment of auditory and visual maps in the barn owl's optic tectum

In the optic tectum (OT) of the barn owl, visual and auditory maps of space are found in close alignment with each other. Experiments in which such alignment has been disrupted have shown a considerable degree of plasticity in the auditory map. The external nucleus of the inferior colliculus (ICx), an auditory center that projects massively to the tectum, is the main site of plasticity; however, it is unclear by what mechanisms the alignment between the auditory map in the ICx and the visual map in the tectum is established and maintained. In this paper, we propose that such map alignment occurs through a process of value-dependent learning. According to this paradigm, value systems, identifiable with neuromodulatory systems having diffuse projections, respond to innate or acquired salient cues and modulate changes in synaptic efficacy in many brain regions. To test the self-consistency of this proposal, we have developed a computer model of the principal neural structures involved in the process of auditory localization in the barn owl. This is complemented by simulations of aspects of the barn owl phenotype and of the experimental environment. In the model, a value system is activated whenever the owl carries out a foveation toward an auditory stimulus. A term representing the diffuse release of a neuromodulator interacts with local pre- and postsynaptic events to determine synaptic changes in the ICx. Through large-scale simulations, we have replicated a number of experimental observations on the development of spatial alignment between the auditory and visual maps during normal visual experience, after the retinal image is shifted through prismatic goggles, and after the reestablishment of normal visual input. The results suggest that value-dependent learning is sufficient to account for the registration of auditory and visual maps of space in the OT of the barn owl, and they lead to a number of experimental predictions.     

Detection of smooth three-dimensional surfaces from optic flow.

An assumption central to the study of 3-dimensional (3-D) shape perception is that sufficient information must be present to detect a 3-D surface. Three experiments were conducted to determine the variables important for the detection of 3-D surfaces from optic flow. Observers were presented with optic-flow displays simulating either points positioned on a corrugated 3-D surface or points randomly positioned within a 3-D volume. The task of the observer was to indicate whether the display appeared to be a 3-D surface. An increase in frequency of the corrugation for simple (single-frequency corrugation) surfaces resulted in a decrease in surface detection. Detection performance increased with an increase in density and amplitude for both simple and complex (multiple-frequency corrugation) surfaces. An analysis of the deformation of the displays suggests that 3-D surface detection may be based on the summed absolute value of the 2 shear components of deformation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Photography of the optic disc in the management of glaucoma (author's transl)

Repeated photography of the optic disc is helpful in the management of 1. patients with glaucoma, especially those who do not give reliable results on visual field testing, and 2. patients with ocular hypertension. The changes to be looked for are; a) any increase in the size of the cup, b) any decrease in the width of the rim of tissue between the edge of the cup and the edge of the disc, c) the occurrence of small haemorrhages on the disc, d) changes in the course of vessels on the disc.     

Measurement of optic disc compliance by digitized image analysis in the normal monkey eye

PURPOSE: To characterize the compliance of the normal monkey optic disc under conditions of induced short-term fluctuations in intraocular pressure (IOP). METHODS: In 10 monkeys, one eye was compliance tested on three separate days followed by a single test of the contralateral eye (40 compliance tests). In a testing session, the optic disc was imaged at 2 and 47 minutes (baseline time point) after IOP was lowered to 10 mmHg; then at 2, 17, 32, and 47 minutes after IOP was elevated to 45 mmHg; then at 2, 47, and, in some cases, 92 minutes after IOP was lowered back to 10 mmHg. Eight digitized images were analyzed at each time point, yielding two parameters to characterize the position of the disc: the Mean Position of the Disc (MPD) and the Change from MPDBaseline (the value of MPD at a given time point minus the value for MPD at the baseline time point of that testing session). Analysis of variance (ANOVA) testing was used to evaluate the overall effect of IOP on both parameters while taking into account the effects of variability due to different monkeys and repetitions of the test as well as differences between the two eyes of an individual monkey. With the addition of data from 11 compliance tests performed on eight additional monkeys, the overall results were calculated in terms of the mean Change from MPDBaseline at each time point for a total of 51 compliance testing sessions. RESULTS: The mean Change from MPDBaseline was -28 microns (95% confidence interval, -23 to -33 microns) 47 minutes after elevation of IOP. The disc surface returned to its baseline position 92 minutes after IOP was lowered back to 10 mmHg. Elevation of IOP within a compliance test had a significant effect on the position of the optic disc surface (P = 0.0002, ANOVA), as characterized by the parameter Change from MPDBaseline. Neither the difference in the amount of movement between the two eyes of an individual monkey nor the variability within the three repetitions of the test in a given eye was statistically significant. CONCLUSION: Small, reversible (elastic) posterior deformations of the optic disc surface follow acute elevations of IOP in the normal monkey eye. Detection of acute IOP-induced deformations of the optic disc surface may represent a means by which to mechanically test the deeper load-bearing tissues of the optic nerve head.