Iatrogenic posterior tibial nerve division during ankle arthroscopy

AIM: To evaluate the validity of cumulative rim/disc area (RA/DA) curve analysis as a clinical tool for the identification of glaucoma induced optic disc pathology. METHODS: 71 normal and 83 glaucomatous eyes were evaluated from a series of 154 subjects recruited for this study. For each eye, the cumulative distribution of RA/DA was calculated from 36 equally spaced rim sectors of each optic disc obtained by the automatic evaluation of simultaneous videographics (Image-net X Rev.3/51b). To increase the sensitivity of this analysis in early glaucoma and in normal eyes, these cumulative curves were subsequently divided into two equal segments and the slopes of their respective regression lines compared. RESULTS: The median RA/DA value obtained from the 36 sectors was significantly different in glaucomatous eyes compared with normals (p < 0.001). Nevertheless, the curves (5th-95th percentile of the cumulative curves distribution) of early glaucomatous eyes fell within the normal range. When the cumulative curve of these marginal cases was then divided into two equal segments, the comparison of the slopes of the regression lines showed a significant difference (p < 0.05) in 100% of early glaucomatous eyes. Furthermore, normal eyes were shown to be true negatives in 93% of the cases in which no significant difference between the two slopes was observed. CONCLUSION: Analysis of the RA/DA cumulative curve from 36 sectors of the optic disc was a valid method for the identification of glaucomatous disc pathology; however, a further calculation of the slopes of the two RA/DA regression lines was needed to identify early glaucomatous damage.     

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.     

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.     

The cumulative normalised rim/disc area ratio curve

BACKGROUND: The assessment of the cup of the optic disc depends, among other criteria, on the disc area. A small cup in a small optic disc can indicate an advanced glaucomatous lesion, while on the other hand a large cup in a large optic disc can be normal. Therefore, a cumulative normalised rim/disc area ratio curve could help to distinguish between glaucomatous and normal optic cups. The aim of our study was to calculate normalised rim/disc area ratio curve. METHODS: Heidelberg Retina Tomograph examinations of the optic nerve head of 100 randomly selected eyes of 100 normal subjects were evaluated. We calculated the disc area-adjusted normalised rim/disc area ratio in sectors of 10 degrees. The 95th, 90th and 50th percentiles of each of the 36 sectors were displayed in descending order. RESULTS: In relation to the normal percentile curves, it is possible to display an individual normalised rim/disc area ratio curve. We obtained such curves for a normal optic disc, optic nerve heads with moderate and advanced lesions and a small optic disc with glaucomatous damage. CONCLUSION: We present a new display mode for the results of Heidelberg Retina Tomograph optic nerve head examination, which may be helpful for easy and reliable assessment of the local, diffuse and combined components of glaucomatous optic nerve head damage depending on optic disc size.     

PDGF and TGF-beta induce cell shape changes in invertebrate immunocytes via specific cell surface receptors

BACKGROUND: To compare neuroretinal rim area measurements by confocal scanning laser tomography and planimetric evaluation of optic disc photographs. METHODS: For 221 patients with primary and secondary open angle glaucoma, 72 subjects with ocular hypertension, and 139 normal subjects, the optic disc was morphometrically analysed by the confocal scanning laser tomograph HRT (Heidelberg retina tomograph) and by planimetric evaluation of stereo colour optic disc photographs. RESULTS: Absolute rim area and rim to disc area were significantly (p < 0.0001) larger with the HRT than with planimetric evaluation of photographs. Differences between the two methods were significantly (p < 0.01) larger in normal eyes with small cupping than in normal eyes with large cupping, and differences were significantly (p < 0.01) larger in glaucomatous eyes with marked nerve damage than in glaucomatous eyes with moderate nerve damage. Coefficients of correlations between rim measurements of both methods were R2 = 0.60 for rim to disc area and R2 = 0.33 for absolute rim area. Planimetric measurements of rim area correlated significantly (p < 0.05) better than HRT determinations of rim area with mean visual field defect and retinal nerve fibre layer visibility. CONCLUSIONS: Measurements of absolute rim area and rim to disc area are significantly larger with the HRT compared with planimetry of disc photographs. Differences between both methods depend on disc area, cup size and glaucoma stage. The reason may be that the HRT measures the retinal vessel trunk as part of the neuroretinal rim. The differences between both methods, which should be taken into account if disc measurements performed by both methods are compared with each other, may not influence the main advantage of the HRT--that is, morphological follow up examination of patients with glaucoma.     

Foveal dysfunction and central visual field loss in glaucoma

OBJECTIVE: To determine whether foveal function distal to the ganglion cell layer is an independent predictor of central visual field function in glaucoma. SETTING: University affiliated hospital and private practice. PARTICIPANTS: Twenty-seven eyes (27 patients) with normal-pressure glaucoma, 10 eyes (10 patients) with primary open-angle glaucoma, and 47 eyes of 47 matched normal volunteers. INTERVENTION AND MAIN OUTCOME MEASURES: Foveal cone electroretinogram (ERG) amplitude, relative optic cup to disc area and their relations to Humphrey full-threshold 30-2 visual field central 4-point mean total deviation (C4MTD) and pattern deviation (C4MPD). RESULTS: Foveal cone ERG amplitude was subnormal in 14 (37.8%) of the 37 glaucomatous eyes and lower in the glaucoma group compared with normal eyes (P<.01). The C4MTD and C4MPD were lower in glaucomatous eyes with subnormal amplitudes compared with those with normal amplitudes (P<.01 and P<.05, respectively). Amplitude was directly correlated with C4MTD (P<.01) and C4MPD (P<.01). Relative optic cup to disc area was inversely correlated with C4MTD (P<.001) and C4MPD (P<.001). Partial correlation analysis revealed that amplitude and relative optic cup to disc area were independent predictors of C4MTD and C4MPD. CONCLUSION: Foveal function distal to the ganglion cell layer and optic disc cupping independently predict central visual field function in glaucoma.     

Ophthalmoscopic assessment of the size of the optic nerve papilla

PURPOSE: To examine whether the optic disc size can be measured with common ophthalmoscopic lenses. PATIENTS AND METHODS: The horizontal and vertical disc diameters in 125 eyes of 65 patients were measured ophthalmoscopically using a commercial slit lamp with adjustable length of the beam and a Volk 60 diopters lens or a Volk Superfield lens. The refractive error of the subjects ranged between -7.25 D and +3.25 D (mean +/- S.D.: -0.34 +/- 1.77). Based on these measurements we calculated the optic disc area by applying a modified formula for an ellipse, where area = horizontal diameter x vertical diameter x pi/4. Additionally, we measured planimetrically the horizontal and vertical diameters of the optic disc on color stereo disc photographs after correcting the ocular and camera magnification according to Littmann's method. RESULTS: The values of the horizontal and vertical disc diameters evaluated on the photographs were by factors of 1.0 and 1.5 larger than those values measured with the Volk 60 D lens, and the Volk Superfield lens, respectively. Taking into account these constant linear correction factors, the optic disc diameters as measured by the Volk 60 D lens and the Volk Superfield lens varied by 0.11 +/- 0.09 mm (5.9 +/- 5.1%), and 0.11 +/- 0.09 mm (5.9 +/- 4.9%), respectively, from the values measured on the photographs. The error for the ophthalmoscopic measurement of the disc diameters decreased slightly with increasing disc size. With highly myopic eyes excluded, it was independent of the refractive error. CONCLUSION: For clinical purposes, the optic disc and other structures of the posterior fundus can be determined by ophthalmoscopy using a slit lamp and commonly used ophthalmoscopical lenses.     

zALK-8, a novel type I serine/threonine kinase receptor, is expressed throughout early zebrafish development

AIMS: Progressive loss of neuroretinal rim tissue is known to occur early in glaucoma and measurement of the neuroretinal rim area is possible by magnification corrected analysis of optic disc photographs (planimetry). This study was performed to determine whether the facility to distinguish between glaucomatous and normal optic discs could be improved upon by: (a) taking into account the known relation between optic disc size and neuroretinal rim area, and (b) measuring rim area in a number of segments, in order to detect focal changes. METHODS: Planimetric examination of the optic disc photographs of 88 control subjects and 51 patients with early visual field defects was performed. In the control group, multiple linear regression analysis was performed between neuroretinal rim area and optic disc area, age, sex, eye side, refraction, and keratometry. This was repeated for the whole disc and for each of twelve 30 degree segments. Normal ranges were defined by the 98% prediction intervals of the regression analysis and the sensitivity and specificity for correct identification of optic discs in the two groups determined. RESULTS: Multiple linear regression demonstrated significant associations between the neuroretinal rim area and optic disc area and age in normal subjects. Sensitivity and specificity for glaucoma diagnosis, using the cut off derived from the 98% prediction intervals, was 37.7% and 98.9% respectively when total neuroretinal rim area alone was considered, and 88.7% and 94.3% respectively when the 30 degree segments were included. The most frequent pattern of neuroretinal rim loss was diffuse, followed by thinning in more than one sector and then by thinning in the inferotemporal sector alone. CONCLUSIONS: This method of optic disc analysis enables the examiner to identify glaucomatous optic discs at the stage of early perimetric loss with a high degree of precision. Optic disc photography is simple, and fundus cameras are widely available. This method for glaucoma case identification may therefore be suitable for the primary care setting as well as hospital practice.     

Morphometric analysis of the optic disc surface. The level of smoothness as a diagnostic parameter for glaucoma

PURPOSE: Since the glaucomatous loss of nerve fibers changes the appearance of the optic disc, we evaluated the morphology of the surface of the optic disc in normal and glaucomatous eyes by using a computerized system to provide the reciprocal position of a large number of points placed on its surface in order to study the clinical significance of differences in the 'smoothness' of optic disc surface. METHODS: The morphology of the optic disc surface was evaluated by means of simultaneous stereoscopic videographic pictures (IMAGEnet X Rev-3.51b-Topcon Europe, The Netherlands): the reciprocal distribution of a large number of points located on the surface of one eye of 100 subjects randomly chosen (45 normal and 55 glaucoma patients) was studied. In order to define the level of 'smoothness' of the optic disc surface, the differences of the relative position of each surface point were studied by measuring the standard deviation (SD) from the average heights of the points (n. ranging from 623 to 1916 depending on the size of the disc area) that identify the optic disc surface. RESULTS: The coefficient of variation of the reciprocal location of the points, placed on the optic disc surface at the different measurements performed by a single operator was 10.4%. The differences in Optic Disc Surface Smoothness (ODSS) between glaucoma and normal group were statistically significant (p < 0.0001 using Mann-Whitney U test). No correlation was detectable between age and standard deviation. The best threshold value, calculated using ROC methodology, able to separate the two groups was: normal group: SD < or = 17.79 (-1 x 10(-2) mm); glaucoma group: SD > -17.79 (-1 x 10(-2) mm). Such threshold value had a sensitivity of 82.1%, a specificity of 92.2% and a diagnostic precision (DP) of 86.5% in dividing the glaucoma group from the normal group. CONCLUSION: ODSS is a global index of optic disc conditions based on quantitative measurements of the morphology of the optic disc surface. As such it does not provide information about the location and the characteristics of optic disc damage. Nevertheless, ODSS measurement is able to separate normal from glaucomatous optic disc with a rather interesting sensitivity, specificity and diagnostic precision (DP). As such it could be useful both for research and clinical applications.     

Neuroretinal rim width ratios in morphological glaucoma diagnosis

AIMS: To 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. METHODS: Colour stereo optic disc photographs of 527 normal subjects, 100 ocular hypertensive individuals with normal visual fields, and 202 open angle glaucoma patients with a mean perimetric defect of less than 10 dB were morphometrically evaluated. Eyes with an optic cup area of < 0.2 mm2 were excluded. RESULTS: In the normal subjects, inferior to temporal rim width ratio (1.67 (SD 0.53)) was significantly (p < 0.0001) higher than superior to temporal rim width ratio (1.56 (0.49)). Both ratios were significantly (p < 0.0001) higher the more vertically the optic disc was configured. In the normal eyes, both ratios were statistically independent of disc size, rim area, refractive error, age, and sex. With the differences being more marked for the inferior to temporal ratio than for the superior to temporal ratio, both rim width ratios were significantly (p < 0.005) lower in the ocular hypertensive group than in the normal group. Despite the high significance of the differences, diagnostic power of the inferior ratio and the superior ratio was 59% and 58%, respectively, indicating a marked overlap between the groups. CONCLUSIONS: Abnormally low inferior to temporal and superior to temporal rim width ratios can indicate glaucomatous optic nerve damage in some ocular hypertensive eyes. Being independent of optic disc size and ocular magnification, the rim width ratios may be taken as one among other variables for the ophthalmoscopic optic disc evaluation, taking into account, however, a pronounced overlap between normal eyes and ocular hypertensive eyes.     

Parapapillary chorioretinal atrophy in patients with ocular hypertension. II. An evaluation of progressive changes

OBJECTIVE: To determine whether parapapillary chorioretinal atrophy in patients with ocular hypertension remained stationary or progressed along with glaucomatous optic nerve damage. METHODS: The morphometric parameters and progression of parapapillary atrophy were retrospectively investigated, using serial photographs, in 350 eyes of 175 patients with ocular hypertension. The association of parapapillary atrophy progression with subsequent glaucomatous conversion and with other baseline patient- and eye-specific characteristics was analyzed. RESULTS: Progression in the area and extension of parapapillary atrophy before noticeable optic disc or visual field changes was observed in 48 (49.0%) of 98 eyes that converted to glaucoma, while parapapillary atrophy progression was noted in 25 (9.9%) of 252 ocular hypertensive eyes that did not develop glaucomatous damage (P<.001). The predictive sensitivity and specificity of this observation were 49% and 90%, respectively. In a logistic multiple regression model, the progression of parapapillary atrophy was associated with a family history of glaucoma (odds ratio, 2.7) and the initial size of zone beta (odds ratio, 1.64, for an increase of 0.10 of the zone beta area-disc area ratio). CONCLUSION: The progression of parapapillary chorioretinal atrophy may be an early glaucomatous finding in some patients with ocular hypertension.     

Bad ethics, good ethics and the genetic engineering of animals in agriculture

PURPOSE: The purpose of this retrospective study is to compare the measurements of intrapapillary and peripapillary parameters between two observers and test the usefulness of measuring different types of crescents. METHODS: Optic disc photographs of 23 eyes of 23 patients with glaucoma and 23 age-matched normal eyes were measured in Oulu and in Erlangen using manual planimetric techniques. The authors measured the following magnification corrected intrapapillary and peripapillary areas: optic disc, neuroretinal rim, cup: disc area ratio, scleral ring, central (zone beta), and peripheral peripapillary atrophy (zone alpha). Twenty-one patients with glaucoma had a follow-up of 3.2 years (range, 1.1-4.7 years), and follow-up for 19 control eyes was 3.7 years (range, 2.5-5.9 years). The measurements were performed in a masked fashion for the diagnosis and temporal sequence of the photographs. RESULTS: Central peripapillary atrophy (zone beta) was statistically significantly largest in primary open-angle glaucoma in both centers (Oulu, P=0.003; Erlangen, P=0.004), whereas normal and exfoliative eyes did not differ significantly from each other. The results for peripheral peripapillary atrophy (zone alpha) and scleral ring were less consistent. Despite statistically significant interobserver correlations ranging from r=0.30 (scleral ring area; P=0.0472) to r=0.97 (optic disc area; P=0.0001), the means of all parameters, except for zone alpha and beta, differed statistically significantly between the two observers. CONCLUSIONS: The central peripapillary atrophy, or zone beta, is the most reproducible parameter when measuring peripapillary atrophy in glaucoma. Nonetheless, its measurement is of limited usefulness in the recognition of glaucoma or progression of glaucomatous nerve damage.     

Optic disc shape, corneal astigmatism, and amblyopia

OBJECTIVE: The cornea and the optic disc form the anteroposterior opening of the sclera. This study evaluated whether an abnormal shape of the optic disc is associated with an abnormal configuration of the cornea measured as corneal astigmatism. DESIGN: The study design was a cross-sectional one. PARTICIPANTS: The study included 882 subjects (430 women, 452 men) with a mean age of 45.9 +/- 13.6 years (mean +/- standard deviation; range, 8-87 years) and a mean refractive error of -1.09 +/- 2.76 diopters (range, -21.0 diopters to +7.0 diopters). INTERVENTION: Corneal astigmatism was determined by keratometry, and the optic disc was analyzed morphometrically by planimetric evaluation of optic disc photographs. MAIN OUTCOME MEASURES: Corneal astigmatism, ratio of minimal-to-maximal disc diameter, and optic disc form factor were measured. RESULTS: The amount of corneal astigmatism was significantly (P < 0.001) correlated with an increasingly elongated optic disc shape. Corneal astigmatism was significantly (P < 0.01) higher in eyes with tilted discs. It was significantly (P = 0.006) smaller in eyes with an almost circular disc shape. Amblyopia was significantly (P < 0.05) associated with an elongated optic disc shape and high corneal astigmatism. The axis of corneal astigmatism was correlated with the orientation of the longest disc diameter. The optic disc was significantly (P < 0.05; chi-square test) more often horizontally oval in eyes with a steeper horizontal corneal meridian than in eyes with a steeper vertical corneal meridian. Correspondingly, the disc was significantly (P < 0.05) more often vertically oval in eyes with a steeper vertical corneal meridian than in eyes with a steeper horizontal corneal meridian. CONCLUSIONS: An abnormal optic disc shape is significantly correlated with corneal astigmatism. Especially in young children, if an abnormal optic disc shape is found on routine ophthalmoscopy, refractometry should be performed to rule out corneal astigmatism and to prevent amblyopia. The direction of the longest optic disc diameter can indicate the axis of corneal astigmatism.     

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.     

Glaucoma and vasospasm

AIMS/BACKGROUND: To study the vasoactivity of glaucoma patients with four previously described and distinct disc appearances potentially representative of primary open angle glaucoma subgroups. METHODS: Patients with pure examples of four glaucomatous optic disc types--focal ischaemic, myopic glaucomatous, senile sclerotic, and those with generalised cup enlargement, were selected. A detailed ophthalmic, systemic, drug, and smoking history was taken from the patients who, in addition, underwent assessment of peripheral vasospasm with a laser Doppler flowmeter. Differences between the groups were evaluated using an analysis of variance, Student's t test, Pearson's chi 2 test, Fisher's exact test together with Spearman's and Pearson's correlation tests. RESULTS: 38 patients with focal ischaemic, 37 with myopic glaucomatous, 24 with senile sclerotic, and 24 with discs characterised by generalised cup enlargement met the selection criteria. The group of patients with focal ischaemic discs contained more women (66% versus 32%-50% in the other three groups; p = 0.01) and had a higher prevalence of vasospasm (63% versus 25%-49%; p = 0.01), migraine (32% versus 8%-19%; p = 0.02), and cold extremities (66% versus 17%-30%; p = 0.00003). The group of patients with senile sclerotic discs had a higher prevalence of systemic cardiovascular disease (58% versus 21%-30% in the other three groups; p = 0.01) and thyroid disease (21% cf 0%-8%; p = 0.01) and although their mean age was greater (76 years cf 55-65 years; p < 0.00001) the findings were independent of age. Smoking was unrelated to optic disc type. CONCLUSION: Vasospasm, previously associated with normal tension glaucoma, and generalised cardiovascular disease both appear to be specific risk factors for the development of particular subgroups of glaucoma and may be independent of absolute intraocular pressure levels exerting effects in patients with both "normal" or "raised" intraocular pressure. The simple assessment as to whether a glaucoma patient suffers from colder extremities than average appeared to be better at distinguishing the focal ischaemic type of glaucoma than the more complex determination of vasospasm using the laser Doppler flowmeter.     

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.     

Laser scanning tomography of the optic nerve head in ocular hypertension and glaucoma

BACKGROUND: This study evaluated the ability of laser scanning tomography to distinguish between normal and glaucomatous optic nerve heads, and between glaucomatous subjects with and without field loss. METHODS: 57 subjects were classified into three diagnostic groups: subjects with elevated intraocular pressure, normal optic nerve heads, and normal visual fields (n = 10); subjects with glaucomatous optic neuropathy and normal visual fields (n = 30); and subjects with glaucomatous optic neuropathy and repeatable visual field abnormality (n = 17). Three 10 degrees image series were acquired on each subject using the Heidelberg retina tomograph (HRT). From the 14 HRT stereometric variables, three were selected a priori for evaluation: (1) volume above reference (neuroretinal rim volume), (2) third moment in contour (cup shape), and (3) height variation contour (variation in relative nerve fibre layer height at the disc margin). Data were analysed using analysis of covariance, with age as the covariate. RESULTS: Volume above reference, third moment in contour, and mean height contour were significantly different between each of the three diagnostic groups (p < 0.001). Height variation contour showed no significant difference among the three diagnostic groups (p = 0.906). CONCLUSIONS: The HRT variables measuring rim volume, cup shape, and mean nerve fibre layer height distinguished between (1) subjects with elevated intraocular pressures and normal nerve heads, and glaucomatous optic nerve heads, and (2) glaucomatous optic nerve heads with and without repeatable visual field abnormality. This study did not directly assess the ability of the HRT to identify patients at risk of developing glaucoma. It is hypothesised that the greatest potential benefit of laser scanning tomography will be in the documentation of change within an individual over time.     

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.     

Long-term epinephrine therapy of ocular hypertension

Nineteen patients with symmetrical ocular hypertension and symmetrical cupping of the optic nerves were made asymmetric with respect to intraocular pressure for one to five years by unilateral topical treatment with epinephrine hydrochloride. Development of glaucomatous visual field defects was observed in 32% of the untreated eyes and in none of the treated eyes (P less than .05). Progressive cupping of the optic nerve was noted in 53% of the untreated eyes and in 11% of the treated eyes (P less than .025). Evidence of glaucomatous damage was observed more frequently in subjects maintained on this regimen for longer periods and in subjects with initial horizontal cup/disc ratios greater than 0.4 (P less than .05). None of the eyes, either treated or untreated, with mean intraocular pressures less than 24 mm Hg developed glaucomatous damage during the period of this study.     

Paraoxonase (PON1) gene in mice: sequencing, chromosomal localization and developmental expression

PURPOSE: To retrospectively examine the optic disc photographs of a glaucoma population for optic disc haemorrhages, vascular occlusions and vascular abnormalities. METHODS: The optic disc photographs of 906 eyes of glaucoma and suspect glaucoma patients were examined. Optic disc photographs were taken annually, where possible, with the follow-up period varying between 1 and 14 years duration (mean, 2.89). Glaucoma patients are regularly reviewed every 4-6 months and glaucoma suspects every 1-2 years, depending on the ophthalmologist. Low-tension glaucoma patients were reviewed more frequently (mean, every 2.6 months). The results of the findings were compared to a control group of 39 subjects with a mean follow-up period of 7 years, using Fisher's exact test. RESULTS: It was found that during the period under review, 7.4% (n = 67) of eyes had optic disc haemorrhages. The highest frequency of optic disc haemorrhages (37.5%) was found in the low tension glaucoma group (P = 0.0001) followed by 11% of primary open-angle glaucoma eyes (P = 0.03). In the normal group there were three eyes with optic disc haemorrhages and one with a disc collateral, which constitutes 5.1% vascular changes in this sub-group. Of the study eyes 2.8% had central retinal vein occlusions, 1.3% branch vein occlusion, 1.2% disc vessel abnormalities (loops) and 1.1% disc collaterals. Discrete nerve fibre layer haemorrhages and microaneurysms were found in 0.8% and 1.8% of eyes, respectively. CONCLUSIONS: A total of 16.8% of the eyes observed in this study had either disc haemorrhages or vascular changes. The underlying trend of vascular and haemorrhagic changes in glaucoma are demonstrated in this sample, which is in general agreement with previous studies. The high percentage of optic disc haemorrhages in low tension glaucoma is highlighted. The presence of microaneurysms and nerve fibre layer haemorrhages is interesting but of unknown significance.