270 consecutive patients with rheumatoid arthritis who had received chloroquine therapy were examined ophthalmologically for toxic retinal lesions. The total annual dose of chloroquine was 70-75 g. The maximum total dose given was 1330 g. The duration of treatment ranged up to 15 years. The primary material was divided into four groups according to total chloroquine dose received: greater than 100 g, 101-300 g, 301-600 g, and less than 600 g. Each dose group was arbitrarily split into two age groups, one with patients under 63 years of age and the other with patients over 63, in order to analyse the effect of age upon the ocular findings. In the present study, slight macular changes were included in the concept of maculopathy and were not thought to contra-indicate chloroquine therapy. Macular changes were found in about 25% of the patients, regardless of age in the lowest dosage group. The frequency of maculopathy increased with increasing total dose only in the older age group. It was also shown that the frequency of maculopathies and other eye diseases also increased with increasing age. This was evident even from the age of 50. The only patient with chloroquine retinopathy was an inadequately controlled 74-year-old woman. Chloroquine treatment of rheumatoid arthritis in the absence of any other disease which may cause retinopathy implies negligible risks in adult patients under 50 years of age. These patients could be less frequently checked. Older patients require regular ophthalmological checks. It is important to use the smallest effective dose possible, and never higher than 4 mg of chloroquine phosphate/kg body weight and day for 10 months annually; in elderly patients, preferably even lower doses.
Summary.
On stimulation with strong flicker of equal light and dark intervals and 1 stimulus/sec., it has been found possible in man to obtain an electroretinogram (ERG) with two negative and four positive waves.
In normal eyes, adaptation to red light leads to temporary disappearance of the 3rd positive wave, whereas pre‐adaptation to green light enhances the 4th positive wave.
The third, red‐sensitive component was lacking in two pro‐tanopes. This component was present in the third protanope, but was not influenced by adaptation to red light.
A deuteranope exhibited the ordinary ERG but, whereas adaptation to red light enhanced the third positive component in the usual way, the ERG was uninfluenced by adaptation to green light. One patient with deuteranomalopia had an ERG similar to that of normal eyes.
In two totally colour‐blind patients, a photopic ERG was entirely lacking.
The red‐sensitive component is in agreement with experiences of the photopic ERG published earlier. The 4th positive wave is presumably a photopic function, although a specific green‐sensitive component cannot be ruled out. Some properties of the two negative waves are briefly discussed.
Summary.
A photopic electroretinogram (ERG) with two negative and four positive humps was recorded earlier (heck and Rendahl 1957). In the course of dark adaptation, an ERG has now been recorded which appears to contain one additional negative wave and one positive one, evidently the scotopic components.
It has been found possible to suppress the various components of the ERG successively by increasing the light adaptation.
On examination of six deuteranopes, an ordinary photopic ERG was obtained. On adaptation to green light, the fourth component was unaffected in two cases. A markedly decreased sensitivity to green light was observed in a similar way in three subjects with deuteranomaly (a fourth exhibited the same variations as in subjects with normal colour sense).
In the four other deuteranopes, the fourth component was suppressed on adaptation to green light, exactly as in normal eyes; the sensitivity to green light was perhaps increased.
On the basis of this and other investigations of colour blindness, the suggestion is put forward that the first type of deuter‐anopia is due to a lack of “green receptors” in the retina, whereas the second type is to be ascribed to the impulses from retinal receptors with different oolour sensitivity being coupled to the same nerve paths.
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