P. J. Airaksinen

Diffuse Visual Field Loss in Chronic Open-Angle and Low-Tension Glaucoma

We examined 37 eyes of 37 patients with chronic open-angle glaucoma and 24 eyes of 24 patients with low-tension glaucoma. All patients had a scotoma confined to the upper or lower hemifield. Eyes with open-angle glaucoma showed twice as much loss of sensitivity in the spared hemifield as compared to eyes with low-tension glaucoma. These differences were statistically significant.

Development of the standard reference plane for the Heidelberg retina tomograph.

Abstract Background: Topometry of the optic disc is the quantitative assessment of the structure of the optic nerve head by means of three- dimensional parameters. The parameter values depend on definitions of intraocular reference planes. Purpose: To describe the development of intraocular reference planes in laser scanning tomography for the Heidelberg Retina Tomograph (HRT) using image intrinsic data with a fixed offset reference plane (320 µm) and to present a contour-line-based ”flexible” standard reference plane (”SRP”) for calculation of intrapapillary stereometric parameters taking the interindividual variability of optic disc topography into account.Methods: Ten-degree triple images were obtained by laser scanning tomography from 99 glaucoma eyes and 180 normal eyes. The images were evaluated to assess the variability of height measurements of an optic disc border contour-line segment (6° width) corresponding to the site of the papillo-macular bundle as indicated by the average optic disc surface inclination angle. Results: The average optic disc surface inclination angle was –7°±3° below the horizontal meridian (0°). The 6° wide contour-line segment for the SRP was chosen according to the average surface inclination angle (–10° to –4°). The reproducibility of the SRP-segment height measurements was 16.0±10.8 µm for normal eyes and 23.4±18.0 µm for glaucoma eyes. To ensure that the automatic reference level determination for intrapapillary parameters remained below the disc border height, we defined the SRP level at a 50 µm offset (>2 SD of average segment height reproducibility in glaucoma) added to the individual height position of the 6° contour line segment. Conclusion: The flexible standard reference plane allows for automatic determination of intrapapillary variables once a disc border contour line is interactively defined. In contrast to a fixed offset reference plane (e.g. 320 µm below the mean retina height), the interindividual variability of optic disc topography (oblique insertion, glaucomatous surface flattening) is respected at the cost of the need for an accurate optic disc border outline.

Effect of retinal nerve fibre loss on the optic nerve head configuration in early glaucoma

Twenty-nine ocular hypertensive patients with an optic disc haemorrhage, normal optic discs and normal visual fields were followed in this partly retrospective study by means of sequential optic disc stereophotographs and retinal nerve fibre layer (RNFL) photographs for a period of up to 14 years (mean 5.2). During this time early structural glaucoma damage developed in 11 patients (12 eyes). RNFL photographs revealed a nerve fibre loss in 10 of the 12 cases (83%). However, even accurate cup to disc ratio measurements from disc stereophotographs enlarged 20 times showed a measurable increase of horizontal and vertical cup to disc ratios in only 33% and 42% of the pathological cases, respectively. This result indicates that haemorrhage-associated RNFL defects precede measurable changes of the optic disc configuration. Therefore, RNFL photography seems to be a useful and sensitive examination method for the detection of the earliest organic damage in glaucoma.

Hemifield association between blue-on-yellow visual field and optic nerve head topographic measurements

Abstract · Background. Blue-on-yellow (B/Y) perimetry can reveal visual field defects earlier and larger in extent than white-on-white (W/W) perimetry. The Heidelberg Retina Tomograph (HRT) produces a three-dimensional image of the optic disc. The aim of this study was to compare the strength of the association of the B/Y and W/W visual hemifield mean deviation (HMD) variables with the optic nerve head (ONH) morphological variables of the respective area. · Methods. We evaluated one randomly chosen eye of 40 normal subjects and 37 patients with ocular hypertension and different stages of glaucoma. The B/Y and W/W visual fields (program 30-2) were obtained with a Humphrey perimeter. Results of both visual fields were adjusted for the patient’s age and lens transmission index measured with a lens fluorometer. HMD was calculated as the difference between the measured and expected hemifield mean sensitivity values, predicted by the regression model fitted in our nonglaucomatous subject data. The HRT with the software version 1.11 was used to acquire and evaluate the topographic measurements of the optic disc. · Results. The B/Y and W/W visual field HMDs showed statistically significant correlation with ONH parameters such as cup shape measure (CSM), rim volume, rim area, mean retinal nerve fiber layer (RNFL) thickness and RNFL cross-sectional area. With forward stepwise logistic regression analysis using B/Y hemifield data 38% of the glaucoma patient’s normal W/W hemifields were classified abnormal. With the CSM alone in the model 52% of the cases were classified abnormal. · Conclusions: B/Y visual field hemified mean deviation values correlate well with ONH parameters examined with the HRT.

Search for an optimal combination of structural and functional parameters for the diagnosis of glaucoma : Multivariate analysis of confocal scanning laser tomograph, blue-on-yellow visual field and retinal nerve fiber layer data

Abstract Background: The purpose of this study was to evaluate which of the structural and functional parameters – the Heidelberg Retina Tomograph (HRT), white-on-white (W/W) and blue-on-yellow (B/Y) visual fields and semiquantitative retinal nerve fiber layer (RNFL) scoring parameters – can give the best separation between non-glaucomatous and glaucomatous eyes.Methods: Fifty-five subjects were included in this study: 32 non-glaucomatous subjects with mean age of 54 years, and 23 patients with ocular hypertension or glaucoma and mean age of 59 years. The HRT with software 1.11, the Humphrey 30–2 W/W and lens coloration- corrected B/Y visual fields, and semiquantitative RNFL scores were utilized. Stepwise logistic regression analysis was used in finding, from a given set of parameters, a best discriminating parsimonious subset to a logistic model, the discriminatory performance of which was evaluated by the area under the ROC curve. Results: When all the structural and functional variables were considered, the RNFL total overall score gave the best separation between glaucomatous and non-glaucomatous eyes (ROC area 0.98). Without the RNFL scores and optic disc size-dependent HRT parameters in the model, the cup shape measure was selected first (ROC area 0.88). In the second step the RNFL thickness was selected (ROC area 0.91), and in the third step the corrected B/Y mean deviation (MD) was selected (ROC area 0.91). With only the HRT parameters in the model, the cup/disc ratio was selected first (ROC area 0.88). However, when the groups were matched for optic disc size, all disc size-dependent HRT variables lost their discriminant power.Conclusion: Cup shape measure and RNFL thickness, together with age- and lens coloration-corrected MD of the B/Y perimetry provided good discrimination between healthy individuals and patients with glaucoma.

Demonstration of glaucomatous optic disc changes by electronic subtraction.

We describe a new method, the electronic subtraction, for objective, two‐dimensional detection, demonstration and recording of glaucomatous optic disc changes. Siemens subtraction unit M 707 A, based on a double videochain and originally developed for the study of roentgenograms, was used. The results show that this technique is useful in demonstrating the progressive damage of neural tissue of the disc and associated alterations in the course of the vessels. Further development of the electronic subtraction method for glaucomatous optic disc evaluation is discussed.

The use of psychophysical, structural, and electrodiagnostic parameters to identify glaucomatous damage

Fifty-one patients with early glaucoma and 29 patients without the disease had their contrast sensitivity, colour vision, differential light threshold, neuroretinal rim area, retinal nerve fibre layer, pattern-reversal electrogram and visually evoked potential examined. A stepwise discriminant analysis found that the combination of the vertical cup disc ratio, the diffuse nerve fibre layer score and the localized nerve fibre layer score correctly identified 98% of the normals and 84% of the glaucoma patients. Single parameters and various combinations of parameters were also examined for their ability to discriminate between the two groups. Fifty-two glaucoma suspects were similarly examined and were classified into those whose discriminant functions were normal or abnormal.

Timolol treatment of chronic open-angle glaucoma and ocular hypertension. A 2.5-year multicenter study.

Maintenance effect of topical timolol was investigated or 2 years in a group of 125 glaucomatous and ocular hypertensive patients (231 eyes) who had been successfully treated with timolol alone during a 6-month period preceding this trial. Intraocular pressure (IOP) was controlled with timolol alone in 135 of 183 eyes (74%) that completed the study. At the end of the trial 142 eyes (78%) showed an IOP of less than 22 mmHg. Other glaucoma medication had to be added to timolol treatment in 18% of ocular hypertensive and 35% of glaucomatous eyes because of IOP elevation. Elevation of IOP seemed to be due to worsening of glaucoma rather than to decreased efficacy of timolol. None of the ocular hypertensive patients developed visual field defects but in ten glaucomatous patients progression of existing visual field defects was observed in association with elevated IOP. Transient adverse effects were observed in 13% of cases, but timolol treatment had to be stopped in only five cases (4%) because of side effects.

ELECTRONIC SUBTRACTION METHOD FOR OPHTHALMIC PHOTOGRAPHY

A commercial electronic subtraction unit orginally intended for the study of roentgenograms was used to produce subtraction pictures of fundus fluorescein angiographies. No modifications were needed to make good quality subtraction pictures. The method is fast and inexpensive in contrast to previously described photographic methods. Certain limitations of the present equipment are discussed as well as some possibilities for further development of the apparatus. The method is especially suitable for studies on dynamic processes in the eye and it should prove valuable in the long‐term follow‐up of chronic diseases such as glaucoma and diabetic retinopathy.

Comparison of the changes in the area of optic disc pallor and visual fields: a 9-year follow-up study

The changes in the optic disc pallor and Friedmann visual fields were compared in 38 glaucomatous, 85 ocular hypertensive and 20 normal eyes during a mean follow-up of 8.9 years. The highest rate of change of both visual field mean defect and pallor area occurred in 35 initially ocular hypertensive patients who developed glaucoma during the follow-up. The changes were second largest in the glaucoma group. Ocular hypertensives who were regarded clinically stable were placed between normals and glaucomas. The measurement of pallor seems to be a more sensitive indicator of glaucoma damage in early glaucoma than in further advanced glaucoma in which visual field examination may be more useful to quantitate progression. The changes of pallor showed good correlation to the changes of neuroretinal rim area.