Retinal dystrophy in long chain 3-hydroxy-acyl-coA dehydrogenase deficiency.

BACKGROUND: Long chain 3-hydroxyacyl-CoA-dehydrogenase (LCHAD) is one of the enzymes involved in the breakdown of fatty acids. A deficiency of this enzyme is associated with life threatening episodes of hypoketotic hypoglycaemia during prolonged fasting. Neuropathy and retinopigmentary changes were mentioned in only a few cases. METHODS: The case histories of two girls, aged 8 and 15 years, with LCHAD deficiency are reported. RESULTS: Both children with LCHAD deficiency exhibited extensive macular pigmentary depositions and a 'salt and pepper' scattering of pigment in their retinas. The patients have decreasing visual acuity. CONCLUSION: The early recognition of LCHAD deficiency can increase the life expectancy in these patients through avoiding catabolism and through appropriate diets. Patients tend to be free of symptoms between attacks, however. Testing for the disorder, therefore, should be included in the diagnostic process for children with retinal dystrophy, in particular when other clinical symptoms are known to have occurred.

Pattern electroretinography in senile macular degeneration.

The value of pattern electroretinography (PERG) for the detection and differentiation of senile macular degeneration (SMD) was assessed. A group of patients with atrophic SMD and a group with exudative SMD were compared with an age-matched reference group. Differences were only found in visual acuity and in the amplitude of the negative peak N95. No statistical differences between the atrophic and exudative groups were found. Conclusions may be drawn from these results with regard to the use of PERG in senile macular degeneration.

Oscillatory potentials in early diabetic retinopathy.

To study the oscillatory potentials in early diabetic retinopathy the authors developed a new power measurement based on the fast Fourier transform. Three groups totalling 46 patients were examined, varying from nonvisible to preproliferative diabetic retinopathy. The oscillatory potentials expressed in microwatts were measured under scotopic and photopic conditions. The data of the three groups are compared with those of a group of 22 normal individuals. The oscillatory potential power measurement appears to be a reliable method in detecting diabetic retinopathy at an early stage.

Measuring oscillatory potential during the course of an arterial occlusion: a method based on Fourier analysis.

Recently we developed a quantitative method of measuring the Oscillatory Potentials (OP's) for a clinical study in diabetic patients. Several problems were experienced in interpreting the results obtained with digital filtering. The main dilemma was the separation of the first OP from the a-wave, since their frequencies are within the same range. The fast Fourier transform (FFT) was applied for this purpose. From the FFT response the power of the OP's was calculated and expressed in microwatts. The advantage of this method is clearly demonstrated in the case of a patient with central retinal arterial occlusion.

Measuring oscillatory potentials: Fourier analysis.

Studying the oscillatory potentials in diabetic retinopathy, the authors experienced several problems interpreting results of digital filtering. The main problem was the separation of the first potential from the a-wave, since their frequencies are within the same range. To improve the procedure of measuring implicit times and of calculating amplitudes, the filtering was started with a finite impulse response filter and followed by a fast Fourier transform. The power of the oscillatory potential was calculated by determining the dominant frequency in the Fourier transformed response and expressed in microwatts. A group of normal subjects was compared with a group of early diabetic retinopathy patients. It appears that even in pathological circumstances a quantitative expression of the oscillatory potential is possible.

Visual function and pattern visual evoked response in optic neuritis.

The disparity between clinical visual function and pattern visual evoked response (VER) was studied in 53 patients who had suffered an attack of optic neuritis (ON) more than six months before. The visual functions tested included Snellen visual acuity, colour vision, visual field, and contrast sensitivity. The effect of pattern presentation, check size, and luminance was tested by recording VERs with several stimulus configurations. VER amplitudes were found to be associated with the outcome of all four clinical tests, independently of check size, luminance, or the presentation method used. On the other hand VER latencies were hardly ever related to the results of any of the four clinical visual tests. These findings support the idea that VER amplitude provides information about visual spatial perception, while VER latency is more related to the extent of demyelination.

Estimation of visual function after optic neuritis: a comparison of clinical tests.

A group of 53 patients who had suffered an attack of unilateral (n = 45) or bilateral (n = 8) optic neuritis more than six months before were subjected to a battery of tests to determine their spatial contrast sensitivity, visual field, and colour vision. The 106 eyes investigated were classified according to their clinical status and visual acuity at the time of the study into unaffected (n = 45), recovered (n = 33), and non-recovered (n = 28). At least one of the three tests gave an abnormal result in 67%, 88%, 100% of the three groups respectively. The results obtained with these three tests showed a significant statistical association.

The pattern-elicited electroretinogram. I. A tool in the early detection of glaucoma?

The pattern-elicited electroretinogram (PERG) was recorded in 75 patients known with glaucoma, each one of them having a normal visual acuity, and compared with the results in normal test subjects. Although there is a great overlap between normal and glaucomatous eyes, a lower average amplitude and a delay in latency is recorded in the case of glaucoma. A correlation was sought between the PERG outcome on the one hand and different glaucomatous parameters (visual field loss, intraocular pressure, cup disc/ratio) on the other; this could only be confirmed for the cup/disc ratio. In beginning glaucoma the PERG is more often disturbed than the VECP.

The pattern-elicited electroretinogram. II. Retinal responses in retrobulbar neuritis.

The pattern ERG is recorded in 54 patients in the acute phase of an optic neuritis. No differences could be recorded between the group of patients and a group of normal test subjects.

Blue-yellow colour vision changes as early symptoms of ethambutol oculotoxicity.

To find out the most sensitive parameter of early toxic ocular changes, a group of patients was extensively examined at regular intervals during therapy with ethambutol. Colour vision abnormalities could be detected using the desaturated panel of Lanthony in the presence of normal visual acuity, normal visual fields, normal visual-evoked potentials and a normal panel D-15 test. Major blue-yellow errors were found in treated patients without visual complaints as well as in a group of healthy volunteers, but there was a significant difference between both groups. In a later stage of intoxication, blue defects, red-green defects or tritanomalous defects can be observed, together with other symptoms of ocular intoxication.

A standardized method for recording pattern-elicited electroretinograms in normal human subjects.

The pattern-elicited electroretinogram may be a useful tool for a further refinement of electro-ophthalmological diagnosis. Before being able to detect abnormalities under various pathological conditions, it is necessary to standardize the procedure and calculate the values for normal human test subjects. The routine procedure for these experiments is described and the data obtained are presented. This method appears to be reproducible and useful and is little time consuming in a diagnostic laboratory set-up.

Electrophysiology in acute anterior ischaemic optic neuropathy.

In a retrospective study of 18 patients, in which 19 eyes were involved, we found in general during the acute phase of an anterior ischaemic optic neuropathy, i.e., within 4 weeks, markedly delayed and reduced pattern-evoked potentials, normal electroretinograms, and decreased electro-oculograms following light stimulation with normal standing potentials. Apart from some sclerosis of the vessels, no other abnormalities of the retinal circulation could be established in our patients. The explanation for the lowered light rise might be the partial and temporary disturbance of the choroidal circulation, which is not extensive enough to influence also the more variable standing potential. In long-standing cases the pattern-evoked potentials seem to remain abnormal, whereas the decreased electro-oculogram following light stimulation recovers.

Component analysis of pattern evoked occipital potentials in hemianopic patients.

In a group of 33 patients with hemianopia, interhemispherical differences of the visually evoked potentials after pattern stimulation were studied. Both full field stimulation and vertical half field stimulation were applied. The results were not consistent, i.e. interhemispherical differences were not always according to the hemianopia. In general, with hemifield stimulation a better score was obtained. Differences between vascular accidents and tumours as the underlying cause of the hemianopia could not be established. With full-field stimulation and a midline electrode hemianopias could not reliably be detected.

Cataract, pattern stimulation and visually evoked potentials.

Visually evoked potentials on pattern stimulation are lowered by cataracts via scatter, absorption and defocusing. These effects have to be known before pattern stimulation can be fruitfully applied in patients when a lowered vision cannot or can hardly be explained by the cataract. It was remarkable that pattern responses were relatively good as compared to visual acuity. With a pattern of 80' check size and 80% contrast all patients with a visual acuity of more than 0.1 had recognizable responses; this holds also true with 40' check size and 40% contrast in all patients with a visual acuity of more than 0.3. Reversely, with 10' check size and 10% contrast only half of the normal subjects had detectable responses.

The value of preoperative electro-ophthalmological examination before cataract extraction.

In 203 senile cataractous eyes preoperative results of photopic flash ERGs and VERs were compared with the optimum visual acuity after cataract extraction. Because preoperatively for some reason a good function of the retina or the conductive system was questionable, patients were referred to the electro-ophthalmological department. This encompassed approximately 10% of patients with a senile cataract. The relationships found indicated that the photopic flash ERGs and VERs are a good support for estimating post-operative visual function.

Electroretinogram and electrooculogram of eyes with intravitreously injected silicone oil.

In clinical and in vitro conditions, the effect of intravitreously injected silicone oil upon the electroretinogram and electrooculogram was investigated. The recorded potentials were lower in the eyes with silicone oil compared to those in which the retinas were reattached without silicone. Retinal changes, caused by the previously existing detachment and the operations already performed, are discussed as possible factors responsible for lower values of the recorded potentials. No arguments could be found in favor of silicone retinopathy.

Pattern evoked cortical potentials and compressive lesions along the visual pathways.

It is stressed that not only demyelinating diseases, but also compressive lesions along the anterior visual pathways, may cause severely disturbed or clearly delayed occipital potentials to pattern reversal stimulation. Only tumors exerting real pressure on optic nerve fibres cause these relatively marked disturbances of the pattern responses. Such tumors are tumors of the optic nerve itself, those along the optic canal, at the base of the anterior fossa or around the chiasm, and not tumors of the orbit or those situated beyond the chiasm.