The antimalarial drugs, chloroquine phosphate (Avlochlor) and hydroxychloroquine sulphate (Plaquenil), have recently been losing favour in clinical practice because of their ocular toxicity. However, simple precautions can be taken to prevent this. The results of serial photography, colour vision assessment, and examination of retinal vessels and fundus periphery, the incidence of corneal deposits and of non-ocular toxicity, and the appearance of sixteen cases with overt maculopathy have been discussed elsewere (Percival and Meanock, I968), and will not now be repeated. This paper investigates further the changes that may occur before the appearance of toxic maculopathy. Material and methods272 outpatients taking part in the survey were referred from the departments of rheumatology and dermatology to the ophthalmic out-patients department during the years i964 and I965. The standard daily dose of the antimalarial was 250 mg. chloroquine phosphate or 200 mg. hydroxychloroquine sulphate, these doses being approximately equal in terms of base-equivalent. 93 patients received double the daily dose during the first part of their course. 43 patients received half the daily dose during the course when control at this level seemed satisfactory. Patients were followed up under ophthalmic supervision at 4-monthly intervals for 2 to 3 years. Several of them had begun therapy some years before referral. Ocular examination comprised: (i) Recording of visual acuity.(2) Assessment of colour vision using the Ishihara pseudo-isochromatic plates.(3) Recording of central fields on the tangent screen to a i mm. white and a 7-5 mm. red target at I metre distance. A central field defect to red was said to be present if there was either a relative or an absolute scotoma to red between 40 and 9°from fixation. In most cases the colour returned to the original red hue outside the scotoma. Central fields to red targets were assessed serially from April, I966, onwards in 230 patients and in ioo control subjects. The latter were selected at random and were matched for age and sex; all had healthy maculae and gave normal readings to the Ishihara plates.(4) Examination of the fundus under mydriasis with particular attention to the foveal reflex. (5) Binocular examination of the macula under high magnification, using a slit lamp and Goldmann contact lens, for the presence of pigment mottling. The test was carried out under mydriasis on I 79 patients. Use was made of both white light and red-free light from the slit lamp. (6) Electro-oculogram (EOG) was recorded using the Moorfields portable apparatus in 24 I patients, and serially in 84 patients once or twice at the commencement of the trial and thence at between oneand two-year intervals. If the reading appeared to be near or below the lower limit of normal it was recorded more frequently.(7) 177 patients were subjected to anaesthesiometry, using four standard nylon hairs as described by Ruben (I964), each requiring a force of 8, 12, I8, and 40 mg. respectively to cause them to bend.

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Hysterical amblyopia is a term used to describe a syndrome in which reduction of visual acuity accompanied by contraction of the visual fields occurs in the absence of any organic lesion. This syndrome has been the subject of many reports (Eames, I 947; Yasuna, 1951; Schlaegel and Quilala, 1955; Krill, I967), but no conclusive diagnostic test has yet been established. Spiralling of the visual fields, and tubular fields which remain unaltered when examined at different distances or with objects of different size, are necessarily of subjective origin and suggestive of hysterical amblyopia (Traquair, I949). Krill (I967) noted an upward shift in the threshold of the dark-adaptation curve after prolonged testing, which he termed the "exhaustion phenomenon" and claimed to be a unique abnormality occurring in hysteria.The most common presenting complaint is of a decrease in vision, which may be associated with headache, night blindness, diplopia, etc.; or there may be no ocular complaints and constricted fields are found on general ophthalmic examination (Heaton, I968). The condition is not unusual among school children (Eames, 1947).The degree to which the symptoms of hysterical amblyopia can mimic those of organic disease is such that in many cases the psychogenic nature is difficult to establish. Electrodiagnostic tests can confirm the integrity of the retina and visual pathways and are a useful aid in differential diagnosis. A number of patients with unexplained reduction of vision have been referred to the Electrodiagnostic Clinic and the methods of analysis used and the results, which have some bearing on the nature of hysterical amblyopia, are the subject of this paper. were under i6 years old.The chief presenting symptom in thirty of the 35 patients was a bilateral blurring of vision or deterioration of visual acuity or, in the case of the children, an inability to see the blackboard clearly. This was associated with headaches in five, diplopia in one, and night blindness in four patients, including one who thought her symptoms were due to avitaminosis A caused by a period in a concentration camp during the war. One patient, whose mother had retinitis pigmentosa, complained of poor side vision.Of the remaining five, two suffered from headaches only, one had difficulty playing ball games, and in two the constricted fields were discovered during examination for non-ocular conditions.All patients had a complete ophthalmological examination and several had neurological or psychiatric investigations in addition.

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