Retinal Function Studies in Hysterical Amblyopia

RETINAL FUNCTION STUDIES IN HYSTERICAL AMBLYOPIA A UNIQUE ABNORMALITY OF DARK ADAPTATION ALEX E. KRILL,

M.D.

Chicago, Illinois

The importance of ocular signs in hys­ teria was first emphasized by Charcot, the great master of neurology.1 He emphasized that hysterical amblyopia is characterized by unique positive as well as negative findings, and indeed this is true. The most prominent optical abnormality found only in this con­ dition is the tubular visual field, which dis­ obeys physical laws by remaining the same size regardless of visual subtense. Another unique finding is visual acuity that varies from time to time or with suggestion. Of other visual abnormalities that have been confirmed as hysterical (conversion) symp­ toms, most can also have an organic basis. It is also possible for conversion symptoms to be superimposed upon an organic disease, making a confusing picture. It is obviously of great importance to have as many positive criteria as possible for the diagnosis of hysterical amblyopia. The purpose of this report is to describe the retinal function findings in 23 patients with subsequently diagnosed hysterical amblyopia and, particularly, to describe a previously unreported dark-adaptation abnormality found only in this condition. METHOD

Fourteen females and nine males were studied (table 1). Many of these patients were referred for retinal function evalua­ tion because visual acuity or visual field abFrom the Eye Research Laboratories, University of Chicago. This study was supported in part by grants NB-03358, NB-03542 and FR-S5 from the National Institutes of Health, Public Health Ser­ vice. Computation was accomplished with the as­ sistance of the Biological Sciences Computation Center, the University of Chicago, under grant FR00013 from the National Institutes of Health, Pub­ lic Health Service.

normalities could not be explained. A diag­ nosis of hysterical amblyopia was made only after complete ocular evaluation plus psychi­ atric, usually, and, when indicated, neurolo­ gic evaluation. All patients had bilateral ocular abnormalities except two (Cases 17 and 19) both of whom had had previous in­ jury to the involved eye but with no residual abnormalities to account for symptoms. Besides the usual examination, ocular evaluation included visual fields and darkadaptation studies in all patients; an electroretinogram (ERG) in 22; color vision testing in 20 (Ishihara and H-R-R pseudoisochromatic plates, Nagel anomaloscope, and Farnsworth Munsell 100 Hue Test) ; electro-oculogram (EOG) in 10; and the visual-evoked response (VER) in four pa­ tients. Central visual fields were tested at both one and two meters. The techniques used for color vision, ERG, EOG and VER studies are described in previous publica­ tions.2"5 Dark-adaptation tests were preceded by an instruction period and practice trial run. The eyes were dilated to 7.0 or 8.0 mm with 1% cyclopentolate. Each subject was initial­ ly adapted to a diffuse white light of 1,346 millilamberts luminance for seven minutes, after which threshold measurements were started immediately. The subject initally fixated on a 2-mm red light of variable brightness, located 15 de­ grees above the center of a test light with a retinal subtense of one degree. The stimulus consisted of light flashes one-second long separated by dark intervals also of one sec­ ond. The calibrated test light was first pre­ sented at a luminance of 0.26 millilamberts with the subsequent direction of change dependent on the response of the subject;

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HYSTERICAL AMBLYOPIA TABLE 1 SURVEY OF FINDINGS

,ase

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Sex

F M M M F M M M F F F F F F F M M M F F F F F

Age (yr) 8 8 8 9 9 11 11 12 12 12 13 13 14 14 16 24 30 34 43 46 46 47 54

Visual Field

Initial Acuity* RE

LE

RE

20/80 20/60 20/200 20/40 20/60 20/80 20/300 20/100 20/60 20/80 20/100 20/60 20/100 20/200 LP 20/20 20/20 20/20 20/20 20/20 20/200 20/200 CF

20/80 20/80 20/200 20/40 20/80 20/100 20/300 20/100 20/60 20/80 20/60 20/80 20/200 20/200 20/100 20/20 20/60 20/30 20/20 20/20 20/100 20/100 CF

— — — — — — — — — — — — — — — N N — — — — —

LE N Abn Abn§ N Abn§ Abn§ Abn Abn Abn§ Abn N Abn§ Abn§ Abn§ Abn Abn

— — — — — — — — — — — — — — — — Abn§ Abn§ Abn§ — Abn§ — Abn§ — Abn — Abn§ —

Maximum Sensi­ tivi tyf N N N N N N N 2.00 3.00 N N N 2.00 1.00 2.00 1.00 3.00# 1.00# 2.00 4.00 1.00 2.00 1.50

Total Upward Threshold Shiftî 0.75 0.75 1.50 N N 1.00 1.50 1.50 1.00 1.00 N N 2.00 1.00 1.00 1.00 1.00# 1.00# 1.00 0.75 0.50 2.00 0.75

Abn = Abnormal. * Corrected distance acuity. t Absolute threshold at 40 min measured in log units above normal (mean plus 2 standard deviations). Î Measured in log units. § Tubular fields. § Abnormal in left eye only.

its maximum luminance was 9.4 log micromicrolamberts. Three or four "on" and "off" thresholds were noted for each test period. An "on" threshold was the intensity at which the subject first saw the light and an "off" threshold was that at which he ceased to see the light. The "absolute threshold" for a test period was the average calculated from the three or four "on" and "off" threshold val­ ues. Rest periods between each test period were one-half minute for the first 10 min­ utes and one minute thereafter. After 40 minutes of testing, thresholds were also determined at five and 25 degrees in the superior meridian and again at 15 de­ grees. In some patients the same three areas were tested in two other meridians. Test pe­ riods were repeated as least four times in each area unless a shift in threshold was

noted ; then at least three or four more test periods were added. RESULTS A.

VISUAL ACUITY

Nineteen patients showed abnormal dis­ tance visual acuities (less than 20/30 with correction) in one or both eyes (table 1). The other four patients were first seen be­ cause of visual field abnormalities. One of the two patients with only unilateral symp­ toms had reduced vision in the involved eye (Case 17). Two of the 19 patients with re­ duced distance vision had normal near vi­ sion. Many patients showed highly variable acuity from day to day or even during the same day. Suggestion improved acuity in some patients. Visual acuity was the first ocular parameter to become normal with im­ proved psychiatric status.

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degrees (Case 16). In 18 of the patients who showed a shift this phenomenon was Twenty patients showed abnormal visual noted on the initial test, whereas in the 19th fields in the involved eye or eyes in initial (Case 2 ) , who was normal on the first test, examination. Thirteen had tubular visual the phenomenon was found on a second test fields in initial or subsequent examination. a week later. One patient (Case 22) had spiral fields; two The raw data from Case 9 (fig. 1) illus­ (Cases 7 and 15) had central scotomas; one (Case 16) had a partial ring scotoma; and trate how consistent "on" and "off" re­ two (Cases 8 and 10) always had bizarre sponses are within each test period but also fields not susceptible to interpretation. Some how the responses shift from one test peri­ of the patients showed tubular fields on only od to another. An unreliable observer is some examinations and a variety of other characterized by "on" and "off" responses abnormalities, sometimes quite bizarre, on which vary markedly and randomly within one test period. Note that there is some fluc­ other examinations. tuation but the threshold shift is definitely in an upward direction. C. DARK-ADAPTATION STUDIES All 13 patients with elevated final thresh­ Absolute final thresholds (at 40 min) olds showed an exhaustion phenomenon. were elevated in 13 patients from 1.0 to However, six patients eventually showing 4.0 log units above normal limits* (table upward shifting thresholds had normal 1). The elevations were usually noted in all thresholds at 40 minutes. tested areas. In general, elevated thresholds Two of the four patients with normal were not limited to retinal areas that were abnormal by visual field examination. How­ dark adaptation (Cases 4 and 11) also had ever, two (Cases 4 and 11) of the three pa­ normal visual fields. These two patients had tients with normal visual fields (Cases 1, 4, abnormal visual acuity only. The data obtained after 40 minutes in the 11) had normal dark adaptation but abnor­ mal visual acuity; and all three had normal dark from hysterical subjects was compared with that from a normal control group using thresholds at 40 minutes. a modification of the Nineteen patients showed an upward . the Welch statistic, G student t-statistic. (The statistic used is shift in threshold with repeated testing in appropriate for comparing two independent one area after prolonged dark adaptation. In samples from normally distributed popula­ 15 of the 19 patients the shift occurred after tions having unequal variances.) The data 40 minutes, in three after 30 minutes (Cases of the first test was used in all subjects. The 9, 15, 22) and in one (Case 19) after 15 numbers used for comparing the two groups minutes in the dark. Although some random fluctuation was frequently noted, this shift were, for each subject, logi0 always tended in the direction of decreased / mean threshold 4th test period \ sensitivity and varied in degree from 0.50 to \ mean threshold 1st test period / 2.0 log units. This threshold change was named the "exhaustion phenomenon" be­ and logio cause of its relationship to time and its di­ mean threshold 5th test period \ rection. In 16 patients the shift was noted in mean threshold 1st test period / all areas tested; in two at five degrees only (Cases 2 and 19) ; and in one at five and 15 for each of the areas tested. In order to make the data conform more reasonably to the assumptions that the sam­ * A threshold above normal is one higher than ples were drawn from two normally dis­ the normal mean plus two standard deviations tributed populations, logarithms were used. (4.9 log micromicrolamberts). B. VISUAL FIELDS

(

HYSTERICAL AMBLYOPIA

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23

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One subject (Case 22) was not included in any of the calculations since there were only three test periods at each area after 40 min­ utes; four to six additional patients (de­ pending on the area as shown in Table 2) were not included in the calculations using the fifth test period since this data was not obtained. Significant differences were found for all ratios compared from the hysterical and normal groups (table 2). These differences were significant at the 0.1% level ( P < 0.001) for five of the six ratios and at the 5.0,% level ( P < 0.05) for the sixth ratio. Follow-up dark-adaptation studies re­ vealed the following points :

1. Dark-adaptation (as well as visual field) abnormalities sometimes persisted after visual acuity became normal. 2. The threshold elevation and the "ex­ haustion phenomenon" were usually repro­ ducible abnormalities with some variation in degree from time to time. Presumably these abnormalities lasted as long as a psycho­ logic basis existed. Case 2 was an exception with initial normal dark adaptation (with abnormal acuity and fields) but an exhaus­ tion phenomenon on retesting a week later. 3. Dark adaptation became normal after patients were thought to have a marked im­ provement in psychiatric status. Four such patients (Cases 1, 13, 16 and 17) eventually

AMERICAN JOURNAL OF OPHTHALMOLOGY

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FEBRUARY, 1967

TABLE 2 STATISTICAL EVALUATION USING WELCH PROCEDURE No. of Subjects

Area ro

0

K»

10

TCO

-3

Normals R. R2 R

l

R2 Rl

R2

T

Hysterics

Degrees of Freedom (F)

P

13 10

22 18

4.42 4.78

25.7 21.7

<0.1% <0.1%

13 8

22 19

5.29 4.42

23.5 20.6

<0.1% <0.1%

13 8

22 16

3.94 2.40

22.4 16.3

<0.1% <5.0%

mean threshold 4th test period mean threshold 1st test period

Ri

mean threshold 5th test period

D.

mean threshold 1st test period

were normal on all visual tests. Initial and follow-up average threshold data are shown for Case 13 (fig. 2). The data are after 45 or 50 minutes in the dark, at which time thresh­ olds were elevated and an exhaustion phe­ nomenon was noted in the first study. Note

that dark adaptation was normal in the sec­ ond study shown. The patient was seen a third time seven months later and absolute thresholds (as well as other visual parame­ ters) were again normal. Of particular interest is a patient (Case

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9) who was markedly improved from a psy­ chiatric standpoint three months after her_ first visit. All visual functions, initially ab­ normal (table 1) were close to normal on the second visit. Fields were normal in the right eye and constricted only with smaller test targets in the left eye, and there was a much lower absolute threshold (almost with­ in a normal range) with no exhaustion phe­ nomenon. Later, with a recurrence of psy­ chologic abnormalities, pronounced darkadaptation and visual-field abnormalities were again noted (although visual acuity re­ mained normal). The average threshold from each test period after 45 minutes of dark adaptation is shown from three reti­ nal areas during five different visits (fig. 3 ) . Three subsequent tests showed elevated thresholds and the exhaustion phenomenon.

D. ERG,

EOG

AND VER

STUDIES

These studies were normal in those pa­ tients tested. E. COLOR-VISION STUDIES

Color vision was normal in 17 of 20 pa­ tients studied. Three patients, all males, had symmetrical partial red-green defects which were thought to be congenital. DISCUSSION

The shift of the absolute threshold in the direction of decreased sensitivity after porlonged testing, the "exhaustion phenome­ non," is a new finding. A number of possi­ ble causative; factors were eliminated before this phenomenon was considered a unique sign of hysterical amblyopia. The data are not an artifact of subject

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unreliability. These patients did not show random variation of response within one test period (as unreliable subjects do) but rather a shift of response (usually in the same direction) from one test period to the next. This phenomenon was not a matter of learning the test since it was seen at the end rather than the beginning of a test. The shift was elicited consistently on different days among some patients and variably on different days among others. This phenomenon was not merely a func­ tion of time in the dark because it has not been observed in any of the 180 other pa­ tients studied here the last three years, who have been tested for at least one hour, in­ cluding 48 who were studied for 90 minutes. An elevated final threshold is not necessary for this phenomenon to occur since six pa­ tients in this study had normal thresholds at 40 minutes but showed this upward shift subsequently. Also, many of the 180 pa­ tients referred to had elevated final thresh­ olds but no exhaustion phenomenon. It is interesting that of the 14 patients of this study who had elevated final thresholds, none complained of night blindness, in marked contrast to another group of sub­ jects. This group includes men of various armed services, particularly during war sit­ uations. Apparently the complaint of night blindness in armies has been noted since the time of the Crusades.7 At least 40 articles on this subject appeared in French, Belgian and German publications during World War I. s Smith, who published in 1921,9 felt that this complaint was always a form of malingering and therefore postponed publi­ cation until after the war. He observed from medical publications that the Germans were accepting as genuine a large number of "malingering" claims for night blindness, and he did not wish to give them any infor­ mation that would enable them to "correct their mistake." During World War II several workers confirmed the validity of soldiers' com­

FEBRUARY, 1967

plaints of night blindness. Subjects were tested on a Koch's modification of a HechtSchlaer adaptometer10 or on a Nagel adaptometer.11'12 In one study absolute thresholds were evaluated at three and 30 minutes in the dark10 in another at 1, 15, 30 and 45 minutes in the dark j 1 1 and in another every five minutes for 40 minutes.1'2 Elevated thresholds were noted in a number of sol­ diers in each study. However, in none was frequent, repeated and prolonged testing at­ tempted, such as was done in the present study. Three other studies in military personnel evaluated identification of letters and ob­ jects under reduced illumination.13"15 Neu­ rotic military personnel, including hysterics, were evaluated and compared with normals. The neurotic group definitely had a worse performance, and in one study two hysterics had the worst scores of all neurotics.13 Later studies included the evaluation of absolute thresholds in psychotic patients.16*18 One worker has evaluated thresholds up to 30 minutes in the dark in heterogeneous groups of psychiatric and neurotic patients. 16 '" With the Crookes adaptometer mild elevations of 0.2 to 0.5 log units were found in most neu­ rotic and psychotic patients.17 However, in two of three hysterics tested thresholds were elevated almost 1.0 log unit. Another worker evaluated thresholds at five intervals for 30 minutes in six psychotic patients using a Hecht-Schlaer adaptometer.18 A significantly higher threshold was found in the psychotic group compared to a normal control group. It is obvious then that an abnormal dark adaptation in hysterical patients is not a new finding. What is new and apparently unique for this group is the shifting thresh­ old, which was probably dependent on the method and duration of the test that we used. The exact explanation for this shifting threshold, as well as for tubular and spiral visual fields, remains a dilemma. Undoubt­ edly central factors are responsible for all of these findings. Certainly much more in-

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gree red target for evaluation of foveal function. Invest. Ophth. 4:303, 1965. 6. Brownlee, K. A. : Statistical Theory and Methodology. New York, John Wiley and Sons, 1960, p. 235. SUMMARY AND CONCLUSION 7. Danis, M.: L'hemeralopie des soldats. Arch. med. Beiges 71:63, 1918. Dark-adaptation studies were done in 23 8.. Culpin, M.: The occupational neurosis (in­ patients with hysterical amblyopia. Elevated cluding miners' nystagmus). Proc. Royal Soc. Med. absolute thresholds were noted in 13 pa­ 26:655, 1933. 9. Smith, H. : Night blindness and the malinger­ tients. In 19 patients an upward shift in ing of night blindness. JAMA, 77:1001, 1921. 10. Michaelson, I. C. : Ocular manifestations of threshold after prolonged testing was noted neurosis commonly found among soldiers. Brit. M. J. which was named the "exhaustion phenome­ 2:538,1943. non." This finding seems to be unique for 11. Parker, F. W.: Studies on dark adaptation in military personnel complaining of "night blind­ hysterical amblyopia. ness." Arch. Ophth. 35 :555, 1946. 12. Wittkower, E., Rodger, T. F., Scott, G. I., and 950 East 59th Street (60637). Semeonoff, B. : Night blindness : A psycho-physio­ logical study. Brit. M. J. 2:571, 607, 1941. REFERENCES 13. Livingston, P. C., and Bolton, B. : Night visu­ 1. Parinaud, M. : The ocular manifestations of al capacity of psychological cases. Lancet, 1:263, hysteria. In Norris, W. F. and Oliver, C. A.: Sys­ 1943. tem of Diseases of the Ej'e. Philadelphia, Lippin14. Rees, W. L. : Night visual capacity of neurot cott, 1900. ic soldiers. J. Neurol. Psychiat. 8:34, 1945. 2. Krill, A. E., and Beutler, E.: The red-light ab­ 15. Himmelweit, H., Desai, M. and Pétrie, A.: solute threshold in hétérozygote protan carriers: An experimental investigation of neuroticism. J. Possible genetic implications. Invest. Ophth. 2:107, Personality, 15:173, 1946. 1964. 16. Granger, R. W. : The night visual ability of 3. Krill, A. E., and Lee, G. B. : The electroretino- the psychiatric patients. Brit. J. Physiol. Optics, 11:226, 1954. gram in albinos and carriers of the ocular albino 17. .: Dark adaptation in neurotic pa­ trait. Arch. Ophth. 69 :32, 1963. 4. Krill, A. E., and Klien, B. A. : Flecked retina tients. J. Ment. Sci. 101:345, 1955. syndrome. Arch. Ophth. 74:496, 1965. 18. Rubin, L. S., and Stein, G. H. : Scotopic visi­ 5. Potts, A. M., and Nagaya, T.: Studies on the bility in normals and psychotics J. Clin. Exper. Psy­ visual evoked response: I. The use of the 0.06 de­ chopath. 21:231, 1960.

formation is needed on the possible influence of cortical mechanisms on subjective visual performance.

OPHTHALMIC MINIATURE

Mary Anne W., aet. 49, suffers from well-marked keratitis of her right eye only ; the dots on the posterior lamina are chiefly at the lower part. The iris has a slightly greenish tint, but shows no undoubted signs of present or past inflammation. The opposite iris is of a bright brown colour. The tension is slightly increased. The eye has been failing for about 12 months. She has had neither pain nor redness in it. It is her first attack. She has dark hair, brown irides, and a sallow complexion. Jonathan Hutchinson, On arthritic iritis, etc. Royal London Ophth. Hosp. Reports, 7(pt 4) :487, 1873