A. De Rouck

Progressive Generalized Cone Dysfunction

The mainly electro-retinographical concept ‘cone dysfunction’, as described by Sloan & Brown (1962), Goodman et al. (1963, 1966), Berson et al. (1968), Krill et al., (1970, 1973), Babel & Stangos (1972, 1973), includes a wide group of clinical pictures.

Morphometric and electrophysiologic study of the photoreceptors in the horse.

Although there is both a morphological resemblance of the photoreceptors and an electroretinographic similarity, in man and in the horse, in the latter there is no proper macula. Moreover, over the whole of the retina of the horse, the rods predominate over the cones.

Progressive Cone Dystrophies

Patients with progressive generalized cone dystrophy often present nystagmus (or strabism) and complain of photophobia, decrease in visual acuity or disturbances in colour perception. The most classic fundus abnormality is the bulls eye maculopathy or a pallor of the optic disc. Minimal macular changes are sometimes seen, which may progress to a bulls eye type of macular degeneration. The photopic ERG is always very affected, whereas at first the scotopic ERG seems normal. Progressive deterioration of the visual functions is accompanied by increasing fundus lesions and rod involvement, as suggested by the modifications of the dark adaptation curve and the scotopic ERG. However, the progression of typical generalized cone dysfunction is very slow. On the contrary, in some cases of so-called Stargardts disease with peripheral participation, a very rapid progression has been observed. In such cases a normal ERG does not necessarily mean that the disease will remain localized to the macular area. No definite prognosis can be made on one single ERG. In 3 cases with sector pigmentary retinopathy the photopic ERG was more affected than the scotopic ERG. However, these cases are probably primary cone-rod dystrophies. Although there is no electrophysiological control, our clinical impression is that the evolution, if possible, is very slow.

Electroretinographical Study of the Hypoplasia of the Optic Nerve

Out of 22 sporadic cases of hypoplasia of the optic nerve, 16 were bilateral and 6 unilateral. The sex distribution was equal in the bilateral cases, while all our unilateral cases were females. Visual impariment was severe in all our cases. There was total blindness or only light perception. The pupillary reflexes were absent or very slow. Only one case had a rather good visual acuity (1/10) with a constricted visual field. In addition to the typical aspect of hypoplasia of the optic disc, some cases showed an obvious or suspected retinal degereration, such as a marked choroidal pattern with pigmentary dystrophy of the posterior pole. The ERG was normal in most cases, and showed no modification with increasing age. No supranormal recordings were obtained. Out of 36 eyes, 12 had a subnormal response. Seven showed an involvement only of the scotopic response, one only of the photopic response and four of both responses. The reduction of the ERG amplitude was rather mild in most cases. The ERG was never extinguished. The temporal characteristics were normal in all our cases with two exceptions.

Ophthalmological aspects of chronic CS2 intoxication.

As a pilot study preliminary to a large scale survey on chronic CS2 toxicity 30 workers of a viscose rayon industry in Belgium have been examined. Twenty of them were working in the xanthation spinning department where chronic CS2 intoxication is more likely to occur and ten controls were chosen form the supposedly safe bleaching division. Ophthalmological evaluation included visual fields, coulour vision testing, fluoro-angiography, ERG and EOG. In both groups fundus anomalies, abnormal EOGs and subnormal or supranormal ERGs were found. The fundus anomalies consisted either of discrete pigmentary changes in the posterior pole or microvascular retinal lesions.

Retrolental Fibroplasia and ERG

From the prognostic point of view, an electroretinogram is important in retrolental fibroplasia. Of the 98 personally examined cases in the last years, 65 (66%) had an extinguished ERG and belonged to the cicatricial stage grade IV or V. Thirty-two cases (34%) had some ERG response in one or both eyes (55 eyes). It may be predicted that a case with extinguished ERG has a poor prognosis and that vitrectomy with retinal attachment will not improve the function.

Electrophysiological Studies in Groenblad-strandberg Syndrome

Fifteen cases (30 eyes) of Groenblad-Strandberg pseudoxanthoma elasticum were examined on the electrophysiological point of view. In only more or less 50% of the cases the results were subnormal. The diamox-test, which may be a functional test of the pigment epithelium, was also abnormal in 50% of the cases. Its significance is still not clear.

Electrophysiological Aspects in Retinal Venous Thrombosis

Electrophysiological examinations, including EOG and ERG, were performed in 19 cases of retinal venous obstruction (8 branch occlusions, 11 total occlusions of the central retinal vein). A few were examined during the first week, others more than 6 months after the onset.

Specific dyslexia with familial neurological defects: A problem in genetic counseling

After having described the clinical picture of specific dyslexia with its visuo-spatial and audio-verbal subtypes, the authors summarize the etiologic hypotheses which are currently accepted, i.e., a cerebral deficit of symbolic integration possibly accompanied by a deficit of visuo-motor organization. they stress the importance of a neuropsychologic test battery in the diagnostic procedure. Problems in genetic counselling, which result from uncertainty concerning the transmission, either irregular autosomal dominant or polygenic, are presented. Two families are described in which, besides proven specific dyslexia, neurological anomalies were seen in the relatives. is it a coincidence or not? the correlation between erratic eye movements and specific dyslexia opens up new perspectives in the diagnostic and etiological approach of this disorder.

Pigment Epithelium, Retina Junction and Photoreceptor Distribution in Man and in the Horse

Although there is both a morphological resemblance of the photoreceptors and an electroretinographic similarity, in man and in the horse, in the latter there is no proper macula. Moreover, over the whole of the retina of the horse, the rods predominate over the cones.