Biomedical subjects

B J Lachenmayr

Publications and source records attributed to B J Lachenmayr.

17 recordsLinked to original sources

PubMed1992

Central function and visual field damage in glaucoma.

82 eyes of 82 patients with different types of glaucoma were examined with various psychophysical tests assessing central and paracentral function, including foveal temporal contrast sensitivity function, FM 100-Hue test, and foveal and parafoveal blue-on-yellow-sensitivity. For all eyes visual field tests were performed with the Humphrey-Field-Analyzer, program 30-2. Global visual field indices were calculated as follows: Mean Sensitivity MS, Mean Deviation MD, and Corrected Pattern Standard Deviation CPSD. Linear regression analysis and multiple regression analysis correcting for a possible influence of age between the central and paracentral criteria and the global indices was performed. For the entire study population highly significant correlations are present between foveal and parafoveal blue-on-yellow-sensitivity and MS, MD and CPSD. Whereas in the Normal Tension Glaucoma subgroup (19/82 eyes) no significant correlations are found, the subgroup of 35/82 eyes with markedly elevated intraocular pressure (> or = 30 mmHg) shows highly statistically significant correlations between the low- and high-frequency end of the foveal temporal contrast sensitivity function and foveal and parafoveal blue-on-yellow-sensitivity and the global field indices. The results of the present study support the idea that there are two different mechanisms of glaucomatous damage, one which is pressure-dependent and one which may be pressure-independent. The pressure-dependent mechanism is responsible for deficits of central or paracentral function which are correlated to overall visual field damage.

Chronic Disease↗

PubMed1992

[Glaucoma parameters of the papilla. Comparison of clinical and stereophotography methods with laser scanning tomography].

The observations recorded by laser tomographic scanner (LTS) and with clinical and stereophotographic evaluation of 40 optic discs in the same glaucomatous patients were compared. Quantitative parameters (vertical and horizontal cup-to-disc ratio) and qualitative parameters (nasal excavation, notch, pseudo-pit, overpass, bayonetting) were evaluated. The correlation coefficients for the quantitative parameter ranged from 0.59 to 0.73. The definition of excavation used meant that the values found with the LTS were consistently higher. The qualitative parameter did not differ significantly with the method. Therefore, the LTS can be considered equivalent to the standard methods.

Adult↗

PubMed1992

Flicker perimetry resists retinal image degradation.

The influence of refractive defocus and artificial media opacities on perimetric thresholds in automated light-sense and flicker perimetry was investigated in 20 eyes of 20 normal subjects. Thresholds were determined at 13 locations in the central visual field up to 25 degrees. Refractive defocus was induced by blurring with glasses of +1, +2, +3, +6 and +9 diopters spherical. Three diffusers were used as artificial media opacities, causing a mean reduction of visual acuity to 0.46, 0.08, and 0.02. Blurring of the retinal image by a small defocus or by slight artificial media opacities causes a measurable reduction of light-difference sensitivity. Mean sensitivity (MS) and defocus are related logarithmically (log(MS)/defocus, r = -0.9297; P < 0.0001). The correlation between MS and the luminance factor l15, characterizing the artificial media opacities, is linear (MS/l15, r = -0.9736; P < 0.0001). Flicker fusion frequency resists retinal image degradation much better. Mean flicker frequency (MF) and defocus are related logarithmically (log(MF)/defocus, r = -0.4960; P < 0.0001). The correlation between mean flicker frequency (MF) and the luminance factor l15 is nonlinear (MF/[l15]2, r = 0.8693; P < 0.0001). The results of the present study show that perimetric methods that use temporal threshold criteria, such as flicker fusion frequency, should be more suitable than methods that use static criteria for detecting neuronal damage in the presence of factors that disturb retinal image quality.

Adult↗

PubMed1992

Diffuse field loss and diffuse retinal nerve-fiber loss in glaucoma.

A total of 61 eyes of 61 patients were examined by light-sense, flicker and resolution perimetry. All fields were classified as being normal or showing diffuse loss, localized defects or diffuse plus localized loss. For the assessment of diffuse field loss, cumulative defect curves were derived. Retinal nerve-fiber layer (RNFL) loss was assessed by a semiquantitative scoring technique. In light-sense and flicker perimetry, the total diffuse and total overall RNFL scores for eyes with diffuse field loss were approximately twice those obtained for eyes without diffuse field loss. These differences were highly statistically significant (P = 0.0055 and 0.0087 for light-sense perimetry, P = 0.0033 and 0.0042 for flicker perimetry). In resolution perimetry, eyes with diffuse field loss also showed higher RNFL scores; the differences, however, were not statistically significant. The results show that diffuse field loss in light-sense and flicker perimetry is accompanied by diffuse nerve-fiber loss.

Adult↗

PubMed1992

The selective effects of elevated intraocular pressure on temporal resolution.

Twenty-seven eyes of 27 patients with normal tension glaucoma (NTG), 68 eyes of 68 patients with primary open-angle glaucoma (POAG), and 11 eyes of 11 patients with special forms of high-tension glaucoma (SHTG) including (pigmentary glaucoma, angle-closure glaucoma, secondary glaucoma, etc.), were examined by automated light-sense and temporal resolution perimetry. Light-sense perimetry was performed with the Humphrey Field Analyzer, using program 30-2. Temporal resolution perimetry was conducted with a system developed by Lachenmayr. Global field indices were calculated for all visual fields and modalities: mean defect (MD) for light-sense perimetry and mean flicker defect (FD) for flicker perimetry. For each of the three glaucoma groups there was a significant linear correlation of FD over MD. The slope of the regression line (regression coefficient a) increased with increasing maximal pressure level of the glaucomatous group: for NTG a = 0.6671, for POAG a = -1.2413, and for SHTG a = -2.235. The differences of the regression coefficients between NTG and POAG and between NTG and SHTG were statistically significant (P = 0.0366 and P = 0.0046, respectively). The results of the present study provide evidence that the relative amount of damage to flicker compared to light-sense perimetry increases with increasing maximal pressure level of a glaucomatous population. Thus, flicker perimetry may be a tool for the identification of eyes with pressure-produced damage.

Adult↗

PubMed1992

Diffuse field loss and central visual function in glaucoma.

Eighty-two eyes of 82 patients with different types of glaucoma were examined with program 30-2 of the Humphrey Field Analyzer. Forty-six of 82 eyes (56.1%) had diffuse field loss and 36/82 (43.9%) eyes had no diffuse field loss according to the cumulative defect curves. Various foveal threshold criteria including temporal transfer and color vision were tested in all eyes. All criteria showed a loss of sensitivity in the presence of diffuse field loss. The loss of sensitivity was statistically significant for the high-frequency end of the foveal temporal contrast-sensitivity function (P = 0.0498), for foveal flicker-fusion frequency (P = 0.0275) and for foveal and parafoveal blue-on-yellow sensitivity (fovea: P = 0.0009; 4 parafoveal points: P = 0.0001; 16 points in the central 10 degrees: P < 0.0001). The loss in sensitivity was not statistically significant for the low and intermediate temporal frequencies of the foveal temporal contrast-sensitivity function and for the FM 100-Hue loss score. All temporal threshold criteria showed a low sensitivity (25-37%) and a low negative predictive value (48-50%) for the presence of diffuse field loss. Their specificity (75-94%) and positive predictive value (65-83%) are high, however. Thus, whenever one of the foveal temporal threshold criteria as used in the present study is abnormal, the probability is very high that there is some diffuse field loss.

Adult↗

PubMed1992

Multiple-stimulus presentation and voice control in automated perimetry.

In all, 55 eyes of 55 patients were examined prospectively in random order with the Humphrey field analyzer [central field 76 points, full threshold strategy, single-stimulus presentation, response-button control (HFA 1); central field 76 points, defect-depth strategy, response-button control (HFA 2)] and the Dicon TKS-4000 [central field 76 points, defect-depth strategy, multiple-stimulus presentation, response-button control (DIC 1); central field 76 points, defect-depth strategy, multiple-stimulus presentation, voice control (DIC 2)]. Some 26 patients (47%) had glaucomatous field defects, 7 patients (13%) had lesions of the visual pathway, 5 patients (9%) had normal fields. The other 17 patients (31%) had field defects due to vascular lesions of the retina or the optic nerve, retrobulbar neuritis, cataract, dysthyroid optic neuropathy, disorders of the macula, or human immunodeficiency virus (HIV) retinopathy. The mean testing time for the whole study population was 5.2 +/- 2.7 min for DIC 1. The difference from the mean testing time for HFA 2 (6.4 +/- 2.7 min) is statistically significant (p = 0.0013). DIC 2 reduces the mean testing time to 4.9 +/- 2.6 min. The difference from DIC 1 is not statistically significant (p = 0.8110). A multiple-stimulus presentation and voice control seem to be useful methods to reduce the testing time in automated perimetry without a loss of accuracy. Voice control, as used in the DICON TKS 4000, still has to be improved, however.

Adult↗

PubMed1992

[Visual acuity perimetry. Detection of glaucomatous visual field defects].

50 eyes of 50 patients with different types of glaucoma (27 eyes with POAG, 14 eyes with glaucoma due to pseudoexfoliation, 8 eyes with chronic narrow-angle glaucoma, 1 eye with normal-tension glaucoma) were examined with light-sense perimetry (Humphrey-Field-Analyzer, program 30-2) and resolution perimetry according to Frisén [2-7]. As the field area tested by Frisén's ring perimeter is smaller than that of the HFA, the comparison was restricted to the area of the ring perimeter, so that 50 out of 77 test locations of the HFA were included. In addition to a quantitative comparison with statistical criteria based on age-corrected normal values, a subjective qualitative assessment was established. The quantitative comparison of all hemifields showed good agreement in 61% of eyes, the ring perimeter indicating moderately and markedly increased numbers of defects in 13% and 4% of eyes and the HFA in 18% and 4% of eyes, respectively. Qualitative comparison of the entire fields revealed good agreement in 46% of eyes, with moderately and markedly more defects in 18% and 10% for the ring perimeter and 12% and 14% for the HFA, respectively. The average time needed for examination was 6.0 +/- 1.1 min for the ring perimeter and 17.2 +/- 2.7 min for the HFA. The Global Deviation of the ring perimeter correlates linearly with the Mean Deviation of the HFA (r = 0.4824, P < 0.001).

Adult↗

PubMed1992

[Light perception and flicker perimetry. Effect of refractive error, artificial media opacities and pupillary size].

The influence of defocus, artificial media opacities and pupil size on perimetric thresholds in automated light sense and flicker perimetry was investigated in 20 eyes of 20 normal subjects. Thresholds were determined at 13 locations in the central visual field. Blurring the retinal image by a small defocus or by slight artificial media opacities causes a measurable reduction in light-difference sensitivity. Flicker fusion frequency, however, is much more resistant to degradation of the retinal image. Artificial pupil size has a similar effect on both light-difference sensitivity and flicker fusion frequency. The present study shows that perimetric methods using temporal threshold criteria should be more suitable for the detection of neuronal damage in the presence of factors disturbing the quality of the retinal image than methods using static criteria.

Adult↗

PubMed1991

Light-sense, flicker and resolution perimetry in glaucoma: a comparative study.

A total of 106 eyes of 106 patients with different types of glaucoma were examined by automated light-sense, flicker and resolution perimetry (Humphrey Field Analyzer, program 30-2; flicker perimeter as described by Lachenmayr [16, 18]; resolution perimeter as devised by Frisén [4, 6, 8-11]). The fields were classified in a masked fashion as being normal or as having purely diffuse loss, purely localized loss or diffuse as well as localized loss. As compared with light-sense perimetry, resolution perimetry had a markedly lower sensitivity in the detection of glaucomatous damage (77%) but a high specificity (93%); the comparison of resolution perimetry with flicker perimetry showed similar results (sensitivity, 75%; specificity, 85%). When flicker perimetry was compared with light-sense perimetry and vice versa, the sensitivity was high (95% and 94%, respectively), but the specificity was low (57% and 62%, respectively). The prevalence of detection of diffuse loss by both light-sense and resolution perimetry was related to visual acuity, whereas flicker perimetry did not show such a relationship.

Adult↗

PubMed1991

Diffuse and localized glaucomatous field loss in light-sense, flicker and resolution perimetry.

A total of 75 eyes in 75 patients with different types of glaucoma (21 eyes with low-tension glaucoma, 49 with primary open-angle glaucoma and 5 with pigmentary glaucoma) were examined by automated light-sense, flicker and resolution perimetry. All fields were classified in a masked fashion as being "normal" (N) or as having "diffuse loss" (D), "localized loss" (L) or "diffuse plus localized loss" (DL). The frequency distributions for the various field loss categories were plotted against the highest intraocular pressure ever reported in the patients' records. The frequency distribution for the purely localized defects showed a peak at 20 mmHg and were markedly skewed to low pressure values, whereas those for both diffuse plus localized damage and purely diffuse loss peaked at about 30 mmHg. The data suggest that diffuse field loss may be an indicator of pressure-induced damage.

Adult↗

PubMed1991

Correlation of retinal nerve-fiber-layer loss, changes at the optic nerve head and various psychophysical criteria in glaucoma.

In 61 eyes of 61 patients with glaucoma, semiquantitative assessment of retinal nerve-fiber-layer (RNFL) loss and neuroretinal rim measurement of the optic nerve head by means of the Optic Nerve Head Analyzer were correlated to the outcomes of automated light-sense, flicker and resolution perimetry and the Farnsworth-Munsell (FM) 100-Hue test. A significant influence of age on total RNFL and total diffuse RNFL scores was found, but there was no measurable effect of age on neuroretinal rim area. Total RNFL and total diffuse RNFL scores showed a good correlation to the various visual field indices: total RNFL score vs mean flicker frequency as determined by flicker perimetry, r = -0.606, P less than 0.0001; total RNFL score vs mean sensitivity as determined by light-sense perimetry, r = -0.385, P = 0.002; and total RNFL score vs mean ring score as determined by resolution perimetry, r = 0.341, P = 0.007. There was no significant correlation between RNFL scores and the FM 100-Hue score. Correlation between the neuroretinal rim area and the various psychophysical indices was poor and mostly not statistically significant. The high correlation of flicker scores with RNFL loss provides interest for future applications of this perimetric technique.

Adult↗

PubMed1991

[Diffuse and localized glaucomatous visual field changes in light sense, flicker and visual acuity perimetry. Evidence of pressure damage].

75 eyes of 75 patients with different types of glaucoma (21 eyes with normal-tension glaucoma, 49 eyes with primary open-angle glaucoma and 5 eyes with pigmentary glaucoma) were examined by automated light-sense, flicker and resolution perimetry. All fields were classified as being "normal" (N) or having "diffuse loss" (D), "localized loss" (L) and "diffuse plus localized loss" (DL) in masked fashion. The frequency distributions for the various field loss categories against the highest intraocular pressure ever reported in the patients' records were plotted. The frequency distributions for the purely localized defects show a peak at 20 mmHg and are markedly skewed to low pressure values, while the diffuse plus localized damage and the purely diffuse loss, however, show a peak at about 30 mmHg. The data support the hypothesis that diffuse field loss may be an indicator of pressure-induced damage.

Adult↗

PubMed1991

[Comparative study of various perimetry strategies].

The conventional 4/2 dB bracketing strategy with fixed steps was compared with the "dynamic step unit strategy" (DSU strategy), which is characterized by an increase of step size with defect depth. In order to analyze the intraindividual variability, 6 eyes of 3 normal subjects were tested ten times with both strategies using the PERISTAT 433. The reproducibility of the DSU strategy is better by a factor of approximately 1.1 The comparative examination of 40 eyes of 40 patients with visual field defects resulting from various pathologic conditions using both the Humphrey-Field-Analyzer (program 30-2, 4/2 dB bracketing strategy) and the Peristat 433 (DSU strategy) yielded a clear advantage (by a factor of 3) in time and a lower number of exposures for the DSU strategy. In order to analyze the reproducibility, 15 eyes of 15 patients were tested three times with both methods. The reproducibility of the DSU strategy for relative defects is worse by a factor of 1.6. Overall, the DSU strategy is substantially faster than the conventional 4/2 dB bracketing strategy; this is achieved, however, at the expense of accuracy in relative defects.

Adult↗

PubMed1991

[Changes in the visual field in diabetic retinopathy after grid laser coagulation of the posterior pole of the eye].

The influence of grid laser photocoagulation on the central visual field of 15 eyes with diffuse diabetic maculopathy was studied in a prospective clinical trial. Throughout the 3 month follow-up period, visual fields were monitored by static perimetry using a combination of 30-1 and 30-2 programs of the Humphrey Field Analyzer. Statistical analysis of all clinical parameters shows that visual acuity correlates very well with foveal light difference sensitivity. The overall sensitivity of the 30 degrees field, however, does not correlate significantly with either of them. During the follow-up period, patients' subjective vision improved significantly (p = 0.0234); for the overall sensitivity of the 30 degrees visual field there was a trend towards improvement (p = 0.0692). The sensitivities of the central 10 degrees and 3 degrees of the visual fields, of the fovea and visual acuity did not change. The results of the present study suggest that during the first 3 months after grid photocoagulation of diffuse diabetic macular edema, the treatment affects mainly the retina outside the macula. The improvement in patient vision may be due to these changes in the visual field.

Aged↗

PubMed1991

[Detection of glaucomatous visual field defects using masking campimetry].

A total of 100 eyes of 50 patients with ocular hypertension and glaucoma of different etiology were examined with the Humphrey-Field-Anazlyer (program 30-2) and the noise-field campimeter according to Aulhorn and Köst [1,2]. The sensitivity of noise-field campimetry vs light-sense perimetry, i.e. the percentage of eyes with an abnormal result in light-sense perimetry that were also identified as abnormal by noise-field campimetry, was 86%. The specificity, i.e. the percentage of eyes with ocular hypertension and thus by definition a normal visual field in light-sense perimetry, that were also identified as normal by noise-field campimetry, was 31%. In 12% of eyes light-sense perimetry indicated defects while the result of noise-field campimetry was normal, and in 11% of eyes noise-field campimetry showed defects though there was a normal field according to light-sense perimetry. The subjective comparison of the two methods with regard to extent and location of the field defects showed good agreement in 22% of eyes for fine noise and in 25% for coarse noise. Moderate agreement was found in 32% fine noise and 34% for coarse noise, and poor agreement, in 46% of eyes for fine noise and 41% for coarse noise. Cooperation was good in 84% of patients and was not dependent on age. Deep localized nerve fiber bundle defects are detected reliably with the noise-field campimeter. The detection of small to moderate relative defects or of generalized changes in terms of a diffuse loss, however, is unreliable. The depth of the field defects is not related to the perception of the noise field.

Glaucoma↗

PubMed1991

[Effect of faulty refraction and artificial media opacities on visual acuity perimetry].

For resolution perimetry according to Frisén, 50 test locations in the central visual field are examined. Compared with conventional perimetry the test time is rather short: 5-10 min per eye. For routine application of this new perimetric technique it is important to know to what extent the threshold values are affected by refractive defocus or media opacities. To answer this, 20 eyes of 20 normal subjects were tested both with a refractive defocus (0, +1, +3, +6, +9 and +12 dpt sph) and with artificial media opacities, using occluders according to Bangerter to reduce visual acuity to average values of 0.61, 0.27, 0.14 and 0.07. The results of the present study show that even a slight refractive defocus or a slight artificial media opacity induces a marked increase in threshold values. Mean Ring score MR and defocus are quadratically correlated (MR2/defocus: r = 0.9973, p less than 0.001), and MR is linearly correlated with the Reduced Luminance Factor 1(15) (MR/1(15): r = 0.9978, p less than 0.001). Clinical evaluation of the test results of the ring perimeter thus has to take into account the influence of refractive defocus and media opacities.

Adult↗