The Maddox Rod Test: A Ten-Year Follow-Up*

The Maddox Rod Test: A Ten-Year Follow-Up*

484 J. REIMER WOLTER AND JOHN WOODWORTH HENDERSON Ichtyosis corneae) im System der sogenannten Dystrophien der Hornhaut. Klin. Monatsbl. Augenh., 70...

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484

J. REIMER WOLTER AND JOHN WOODWORTH HENDERSON

Ichtyosis corneae) im System der sogenannten Dystrophien der Hornhaut. Klin. Monatsbl. Augenh., 70: 396, 1923. 20. Stanka, R.: Ueber familaere gittrige Hornhautdegeneration. Klin. Monatsbl. Augenh., 74:357-360, 1925. 21. Loewenstein, A.: Zur Klinik, Histologie und Therapie der gitterfoermigen Hornhautdegeneration. Klin. Monatsbl. Augenh, 82:752-762, 1929. 22. Buecklers, M. : Die erblichen Hornhautdystrophien. Buecherei des Augenarztes. Stuttgart, Ferdinand Enke, 1938. 23. Thomas, C. I.: The Cornea. Springfield, 111, Charles C Thomas, 1955, p. 281. 24. Vrabec, Fr. : Etude neurohistologique d'un cas de dystrophie grillagée de la cornée. Ophthalmologica, 133:160, 1957. 25. Wolter, J. R.: Reactions of the cellular elements of the corneal stroma. Arch. Ophth, 59:873, 1958.

T H E MADDOX ROD T E S T : A TEN-YEAR FOLLOW-UP* DANIEL SNYDACKER,

M.D.

Chicago, Illinois

The value of the Maddox rod as an in­ strument for measuring muscle imbalance has been amply demonstrated by widespread clinical use. A number of careful statistical studies attesting to its value have been re­ ported, of which those by Cridland1 and Scobee and Green 2 ' 3 are of particular value. It is generally assumed that measurements with this instrument show an increase in exophoria with advancing age, particularly at the near-point. The explanation is offered that advancing age brings a decrease in ac­ commodation and an associated decrease in converging power.4 To test this assumption, 100 consecutive private patients were studied who had meas­ urements with a Maddox rod made on ini­ tial examination and again at an interval of 10 years or more. TECHNIQUE OF EXAMINATION

A multiple red Maddox rod combined with a Risley rotary prism was used to measure the phoria (fig. 1). As shown, the Maddox rod was positioned in front of the prism with a specially constructed clip. The prism was hand-held and, when possible, measurements were made with the patient wearing his own glasses. * Presented in part at the 98th annual meeting of the American Ophthalmological Society, Hot Springs, Virginia, May, 1962.

The instrument was invariably held be­ fore the patient's right eye, no attention being paid to ocular dominance. Patients were asked to sit erect and the prism was held so that base horizontal prism could be produced. Patients were found to be extremely critical in judging any devia­ tion of the observed streak of light from the true vertical, so it was not difficult to judge whether the zero point of the prism was at 180 degrees. Measurements were made without screening, as described by Scobee.2 Measurements were made in a 7.5 meter refracting lane. The distance fixation point was a small muscle light. The near fixation point was a small ophthalmoscope bulb held in the reading position about 25 degrees below the horizontal plane. Diffuse, dim over-all illumination provided by an indirect overhead light was the same for each meas­ urement. Only those patients were included in this

Fig. 1 (Snydacker). Risley prism with Maddox rod held in front of it by specially constructed clip.

T H E MADDOX ROD T E S T

series who had had at least two measure­ ments with the Maddox rod at a minimum interval of 10 years. Since the study was limited to patients with normal muscle bal­ ance, any subject who had more than eight prism diopters of esophoria for distance or more than 10 prism diopters of exophoria for near at the first measurement was ex­ cluded, because readings outside these limits have commonly been accepted as abnormal. Furthermore, all patients whose responses were confused or uncertain were excluded from the study. ANALYSIS OF DATA

(tables 1 and 2)

1. There were 49 males and 51 females in the series. No differences in the measure­ ments associated with sex could be demon­ strated. 2. The patients ranged in age at the time of the first examination from five to 63 years. The median age was 33 years and the average age was 32 years. 3. No patient was included who had not been observed for at least 10 years. The longest period of observation was 23 years. The average period of observation was 13.02 years. 4. Measurements were analyzed by as­ suming that orthophoria was the zero point. Exophorias were treated as positive num­ bers and esophorias were treated as negative numbers (fig. 2). Using this convention, the average heterophoria for distance was — 1.08 prism diopters of esophoria on the first measurement, and —1.19 or 1.19 prism diopters of esophoria on the second meas­ urement. The mean difference between the first and second measurement was 0.11 prism diopters which when analyzed sta­ tistically proves to be an insignificant dif­ ference ( P = 0.54). It can be concluded that the second measurement of the hetero­ phoria for distance is substantially the same as the first measured 10 or more years pre­ viously. 5. The mean heterophoria for near on the first examination was 3.23 prism diopters

48S TABLE 1

R A W DATA ON MEASUREMENTS

Measurement 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 MEAN STANDARD DEVIATION

Measurement 16 IS 14 13 12 11 10 9 8 7 6 S 4 3 2 1 0 -1 -2 -3 -4 -5 -6

Distant (first)

2 4 1 53 6 14 5 8 2 4 0 1

Distant (second) 3 2 6 2 30 13 23 7 6 3 4

D1-D2 1 3 2 14 19 33 9 11 4 4

1

-1.08

- 1 . 19

0.11

2.04

2. 23

0.79

Near (first)

Near (second)

N1-N2

1 1 2 4 3 5 1 15 2 16 7 20 2 18 2 3 1 1

2 1 2 6 8 6 22 15 12 10 4 1 3 2 1 1

1 1 1 3 3 6 9 13 10 15 11 8 12 4 3

MEAN

3.23

3 . 64

-0.41

STANDARD DEVIATION

3.22

3 . 44

3.17

of exophoria (+3.23) and on the second was 3.64 prism diopters of exophoria (+3.64) (fig. 3). The difference between these measurements is 0.41, Student's t is — 1.29 and the probability value is 0.20 (fig. 4). This is a difference which from a statistical standpoint is borderline so that one is unable to decide whether there is a

DANIEL SNYDACKER

486 TABLE 2 R A W DATA ON SUBJECTS

Within subject data Mean increase in exophoria for near = 0.41 prism diopters Mean increase in age = 13.02 years Mean increase per year = 0.03149 prism diopters Variance of mean increase per year = 0.0005928 9 5 % confidence interval for increase per year = -0.01690 to 0.07988 Among subject data Mean increase in exophoria for near per year = 0.06598 Prism diopters Variance of mean increase per year = 0.0003880 9 5 % confidence interval for increase per year = 0.0266 to 0.1054 Weighted combination of within subject data and among subject data Mean increase in exophoria for near per year = 0.05232 prism diopters. Variance of mean increase per year = 0.0002345 Standard deviation = 0.01531 9 5 % confidence interval for increase per year = 0.02170 to 0.08294 Student's t for mean increase per year 0.05232 = = 3.42 0.01531 Probability value = approximately 0.002 Statistics for distance measurements Mean of first measurement = 1.08 esophoria Mean of second measurement = 1.19 esophoria Mean difference between measurements = 0.11 Standard error of the difference = 0.179 Student's t = 0.61 P = 0.54 Statistics for near measurements Mean of first measurement = 3.23 exophoria Mean of second measurement = 3.64 exophoria Mean difference between measurements = —0.41 Standard error of the difference = 0.317 Student's t 1.29 P = 0.20 Wilcoxon paired sample rank, P = 0.086

real increase in exophoria with advancing age. 6. Review of the statistics for further evi­ dence of the relationship between exophoria for near and advancing age showed that the technique of linear regression could be ap­ plied. A straight line is the best fit which suggests that on the average, there is a small increase in exophoria for each^ear of ad­ vancing age (fig. 5). If the matter is further pursued and weighted averages are consid­ ered, there turns out to be an increase in

40

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ESO

-a

o

è

F I R S T QISTMvlCE

- 6 ~τ -e O £ SECO MO DISTANCE

MEASUREMENT

EXO

MtA&URCKlENT

EXO

Fig. 2 (Snydacker): Distribution of measure­ ments for distance. Dotted line represents calcu­ lated normal distribution. Single vertical line rep­ resents mean measurement. exophoria for near of 0.05 prism diopter for each year. This is a statistically sig­ nificant increase having a P value of 0.0002. COMMENT

The measurements, particularly those for distance, are remarkably constant, suggest­ ing that the Maddox rod is a useful instru­ ment for evaluating heterophoria. If a marked change from a previous finding is encountered, the examiner should investi­ gate binocular function further to find the cause of such a discrepancy. The Maddox rod is a useful screening device. If the pa­ tient's responses are quick and sure, the examiner is justified in assuming that simul­ taneous macular perception and probably simple motor fusion are present. If the findings are within four or five diopters of the mean figures found in this study, and if the reading is somewhat more exophoria for near than for distance, they can be accepted

THE MADDOX ROD TEST

487

No eo-,

u -4 ESO

Fig. 3 (Snydacker). Distribu­ tion of measurements for near. Note wide spread of measurements and flat normal distribution curve.

-e

3

.u^

E 4 6 FIRST NEAR

E 4 6 8 SECOND NEAR

as normal and no further investigation of muscle balance need be made. If the responses are uncertain, if the endpoint is vague or if the readings are con­ siderably different from the means found in this study, the examiner will be well advised to investigate further. Such discrepancies may be found in heterotropia, amblyopia or any other anomaly of binocular function.

No

eo-,

Γ -6

-4

ESO

-a

o

a

4

fa

DISTANCE ( I ) - D I S T A N C E ( ε )

EXO

It Mc. EXO

EXO

Although the exophoria for near shows a statistically significant increase over a period of time, it is suggested that this increase is not clinically significant. T h e increase which was found to be 0.05 prism diopter p e r year amounts to one prism diopter for each 20 years of life. W i t h a constant measure­ ment for distance and such a very slight change for near, certain deductions may be made: ( 1 ) Measurements made by the tech­ nique used a r e repeatable, hence the method is an accurate o n e ; ( 2 ) innervational factors or other elements which might produce a large variation do not play a large role in influencing heterophoria as measured with the Maddox r o d ; ( 3 ) the normal loss of ac­ commodation which occurs with advancing age does not materially influence any heter­ ophoria which is within normal limits. CONCLUSIONS

N a. SO-,

IO·

o-

r--J

r^ -e> ESO

-4

-e

ό

à

1 1. 4

NEAR (0 - NEAR (ê.)

e

L

e EXO

Fig. 4 (Snydacker). Relative frequency of dif­ ference between first and second measurement for both near and distance.

1. Heterophoria for distance, as measured with the Maddox rod, remains constant with advancing age. 2. Heterophoria for near is not as con­ stant as heterophoria for distance and any conclusions a r e therefore somewhat less def­ inite. Comparisons of measurement in the same patient at different ages, shows a tend­ ency for increasing exophoria for near which is statistically borderline. Measure­ ments of heterophoria for near for the whole series show a statistically significant increase

DANIEL SNYDACKER

488

8-

Fig. S (Snydacker). Linear re­ gression showing increase in exophoria for near with advancing age.

6 4a o

£o

50

40

io

MEASUREMENT = 0 . 9 0 + 0.0659Θ X AGE

in exophoria for near with advancing age. This increase is small, amounting to only one diopter for each 20 years of life. Ill North Wabash (2).

ACKNOWLEDGMENT

I wish to thank Mr. J. M. Becktel for his help with the biostatistics and to D. Snydacker, Jr., for his help with the graphs.

REFERENCES

1. Cridland, N.: The measurement of heterophoria. Brit. J. Ophth., 25:141-167, 188-299, 1941. 2. Scobee, R. G., and Green, E. L.: Tests for heterophoria: Reliability of tests, comparisons between tests and effect of changing testing conditions. Tr. Am. Acad. Ophth., 51:179-197, 1947. 3. : A center for ocular divergence: Does it exist? Am. J. Ophth., 29:422-434, 1946. 4. Duke-Elder, S.: Textbook of Ophthalmology. St. Louis, Mosby, 1949, v. 4, pp. 3949 and 3951.

MESO-ECTODERMAL DYSPLASIA AND ITS VARIANTS* WITH

PARTICULAR REFERENCE TO T H E R O T H M U N D - W E R N E R

EARL H.

M E R Z , M.D.,

KASRIEL TAUSK,

M.D.,

SYNDROME

AND E A R L E D U K E S ,

M.D.

Chicago, Illinois INTRODUCTION

In 1904, Otto Werner, a German oph­ thalmologist, published his thesis, in which he described four cases of "scleroderma as­ sociated with bilateral cataracts" among four siblings ; the cataracts appeared in the sec­ ond or third decade of life. W e r n e r was preceded by another German clinician, Au­ gust Rothmund 2 who, in 1868, wrote a paper entitled, "Cataracts in association with a pe* From the Department of Ophthalmology, Northwestern University Medical School and the Chicago-Wesley Memorial Hospital, and the Dis­ pensary of Presbyterian-St. Luke's Hospital and the College of Medicine, University of Illinois, and the Illinois Research Hospital.

culiar degeneration of the skin." Rothmund described the genealogy of three families, two of them related, in which several in­ fants were suffering from cataracts and, as he named it, marmorization of the skin. T h e skin and eye findings usually became appar­ ent early in life, in a period ranging from three months to six years. It soon became evident that both these entities were closely related ; they were considered by some clini­ cians to be identical. W e have to leave un­ answered the questions: how alike are W e r ­ ner's and Rothmund's syndromes; should they be united by a hyphen and called Rothmund-Werner's syndrome? T h e r e are several noteworthy publications