Hana Langrová

Abnormalities of the long flash ERG in congenital stationary night blindness of the Schubert-Bornschein type.

We investigated abnormalities of the retinal cone ON- and OFF-pathways in 24 males with Schubert-Bornschein congenital stationary night blindness (CSNB). Substantial differences were found between both CSNB types. In incomplete type, a-, b- and d-waves were reduced and delayed, whereas in complete type only the b-wave showed significant changes. Oscillatory potentials (OPs) were not discernible from noise in incomplete CSNB and showed significant peak alterations of the ON-OPs only in complete CSNB. In the complete CSNB type, the ON pathway appeared to be mainly affected. In the incomplete CSNB form marked involvement of both the ON and the OFF pathways was noted.

Age-related changes in retinal functional topography.

PURPOSE To perform a detailed topographical analysis of functional age-related changes over the retina. METHODS Fifty-nine normal phakic subjects aged 10 to 69 years were divided into six groups, according to decade of age. mfERG traces were recorded from the central 60 degrees of the retina, with a resolution of 61 and 103 scaled hexagons. Group medians of peak amplitude and latency of the first- and second-order (first slice) responses were used to generate 3-D topographical maps. RESULTS With age, there was a continuous loss of amplitude and delay of implicit time of the first- and the second-order response components, but the topography of the loss was not uniform across the retina. Trend analyses on ring group data showed a significant decrease in amplitude of first- and second-order responses although the age relationship of second-order responses was more complex. The loss of first-order kernel amplitude was generally accompanied by a rise in implicit time. Second-order kernel latencies showed no uniform alteration with age. CONCLUSIONS Consistent with previous work, a steady loss of amplitude and increase of implicit time was observed with age. The topographical 3-D data, however, reveal age-related functional alterations in the retina beyond those found in ring averages, suggesting that these are masked by the standard analysis. Thus, the choice of physiologically coherent regions of interest may increase the sensitivity of detecting age-related change in multifocal analysis of retinal function.

The multifocal pattern electroretinogram (mfPERG) and cone-isolating stimuli

The number of L cones in the retina normally exceeds that of the M cones. Because normal color vision does not depend on the ratio of L- and M-photoreceptors, their signals must undergo an alteration in gain before being analyzed in the cortex. Previous studies have shown that this gain must take place before the cortex, but after the bipolar/amacrine cell layer of the retina. The aim of this study was to obtain topographical information about L- and M-cone activity at the ganglion cell layer using multifocal pattern electroretinography (mfPERG). A standard (black and white) stimulus was used, as well as stimuli modulating only the long wavelength-sensitive (L) or only the middle wavelength-sensitive (M) cones. The L:M ratio was calculated from the amplitude of the L-cone isolating mfPERG to that of the M-cone isolating mfPERG of 10 trichromats. Both the positive and negative components of the waveform were analyzed. Additional recordings of single cone modulated mfERGs were obtained from nine of the 10 subjects. We also recorded from one protanope and one deuteranope. The L:M cone amplitude ratios for both deflections of the mfPERG in the trichromats were around unity (medians 1.18 and 1.16, respectively) for the central 8 degrees of retina. In the peripheral retina between 12.8 degrees and 26 degrees , this ratio increased to 1.42 for the positive component, and 1.37 for the negative component. The median L:M cone amplitude ratios for the mfPERG were higher and ranged between 1.00-2.78 in the central 8 degrees and 1.29-2.78 in the periphery. The results indicate that a major gain adjustment of the retinal signals takes place at the ganglion cell level, and that the ratio is higher at eccentric locations than in the central retinal area.

Electrophysiology and colour: a comparison of methods to evaluate inner retinal function

PurposeSeveral methods are routinely used in the clinic to diagnose and monitor diseases of inner retinal function. In this study, we compare four such methods in patients with diabetes and glaucoma, to determine correlations between their results and to determine which method is most sensitive for detecting disease.MethodsTwenty control subjects, 12 patients with early glaucoma and eight patients with diabetes mellitus, were enrolled in the study. All underwent four examinations: transient pattern electroretinogram (PERG), multifocal pattern electroretinogram (mfPERG), chromatic contrast threshold measurements (protan and tritan), and blue-on-yellow short-wavelength automated perimetry (SWAP).ResultsFor the total cohort of 40 subjects, the results show a significant correlation between the amplitudes of the PERG and those of the mfPERG, as well as between the tritan contrast thresholds and the SWAP MD. Furthermore, ROC analyses reveal that colour contrast thresholds could significantly distinguish between the patient and the control group. Glaucoma patients alone could also be distinguished.ConclusionsWe conclude that the methods compared in this study show correlations between their results if they are testing same pathway or underling cells, and that the colour contrast threshold is the most sensitive method to detect early functional deficits in diabetic and glaucoma patients.

Topographical alterations of inner retinal activity during systemic hyperoxia-hypercapnia in normal subjects and patients with type 1 diabetes.

The purpose of this study was to investigate whether an increase in the circulating oxygen supply can alter inner retinal function, assessed by recordings of multifocal oscillatory potentials. We studied 9 subjects with type 1 diabetes (8 without overt retinopathy, one with 2 microaneurysms) and 10 similar-aged normal subjects. The central 60° of the retina was stimulated by an array of 61 hexagonal elements, and mfOP recordings were obtained while breathing room air or carbogen. First-order kernel analysis of the recordings shows 2 potentials (first-order OP1, OP2), whereas second-order kernel analysis produces 3 potentials (second-order OP1, OP2, OP3). Two methods were used to analyze the results: First, we performed a ring analysis for each subject and measured the amplitudes and latencies of the five potentials. We demonstrate that during carbogen inhalation, the control subjects, but not the patients with diabetes, showed significantly increased second-order OP3 amplitudes, for a retinal ring from around 1.8–13° eccentricity. Secondly, a topographical analysis was performed on the amplitude of the second-order OP3 in all 61 traces (from the average recordings of each subject group), which revealed significant alterations not visible in a ring analysis. A similar topographical analysis of the amplitude of the first-order OP2 revealed a small increase in its amplitude during carbogen inhalation for both subject groups. This study demonstrates that some aspects of inner retinal function are modified by the inhalation of carbogen. The reduced effect of carbogen inhalation on the recordings from the patients with diabetes may be due to compromised vascular perfusion in these subjects.