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The Crisp-Stine Test
CORRESPONDENCE
310
ethical optometrists are keenly aware of their responsibilities toward these children. The visual-screening program has been in effect for two years now. Only approximate figures can be given at this time but the fol lowing statistics are interesting. Over 150,000 school children in the State of Illinois have, so far, been screened, about 15 percent of whom are shown to need eye care. Up to November 24, 1950, 47,318 chil dren have been screened in Chicago, about 12 percent of whom needed eye care. A con centrated study of 2,429 Chicago school chil dren who were visually handicapped showed that 1,534 of them went to ophthalmologists, 761 to optometrists, 56 to medical eye clinics, 22 to optometric clinics, and only 44 to de partment stores. The function of the Illinois Society for the Prevention of Blindness was to demon strate that such a program was highly impor tant for the welfare of our future citizens, easily carried out, relatively inexpensive, re quiring few numbers of easily trained test ers, and capable of drawing together ethical groups of professional people to do what was considered best for the handicapped child. The society has more than fulfilled its pilot mission. It is now time for the various boards of education to continue and to expand this most worthwhile venture. It is high time for other states to follow suit. Derrick Vail.
CORRESPONDENCE T H E CRISP-STINE TEST
Editor, American Journal of Ophthalmology: Stine, in recent articles in this JOURNAL (32:1128 [Aug.] 1949 and 33:1587 [Oct.] 1950), has well shown the remarkable pre cision that can be attained by the use of the astigmatic dial. In examinations conducted for the American Board of Ophthalmology
I found that when four candidates examined the refraction of the same eye the final cor rection obtained was different in every in stance. Evidently their methods did not as sure reproducible results. Only a few candi dates realized the importance of the astig matic dial and apparently most of them had little or no training in its use. Maddox used an angle of 50 degrees for locating the axis of lesser errors of astig matism, and 25 degrees for high errors. The angle of 60 degrees, used in the Lebensohn astigmometer, is wide enough to be prac tically useful in the Crisp-Stine test.Though the latter employs lines 45 degrees from the reference point, the 15-degree difference means an over-all reduction of 14 percent in effective power of both the applied and induced cross-cylinders but otherwise the same relations are maintained and the mathe matical difference that results is slight. Thus, at the wings of the arrow, the effective power of the 0.125D. applied crosscylinder is plus and minus 0.107D., respec tively. For l.OOD. astigmatism, with fivedegree error in axis, the induced cross-cyljnder effect at the arrow wings is 0.074D. Shifting the applied cross-cylinder from the neutralizing to the aggravating position changes the residual values from 0.033D. to 0.181D. The difference is 0.15D. as opposed to 0.17D. in the original Crisp-Stine test. The unmodified Crisp-Stine test can be used with the Lebensohn astigmometer by placing a small triangle of black Scotch tape at the midpoint of the arc subtending a clear quadrant. With the marker placed at the axis under consideration, the comparisons are then made between the arrow line and the plain line. The next edition of the Lebensohn chart will present this additional marker. A series of cases with various degrees of astigmatism tested by both methods showed a more definite response to one test over the other in even number. Evidently psychologic as well as mathematical factors determine the patient's reaction. When doubt exists, it
311
CORRESPONDENCE is advantageous to use both tests as one test then checks the other. (Signed) James E. Lebensohn, Chicago, Illinois. EXTRAOCULAR MUSCLES
Editor, American Journal of Ophthalmology: In his letter in the AMERICAN JOURNAL OF OPHTHALMOLOGY (33:1305 [Aug.] 1950), Dr. Robert S. Hewitt calls attention to some "erroneous deductions" made by Dr. Am brose in his article on the extraocular mus cles (Am. J. Ophth., 33:793 [May] 1950). Most of Dr. Hewitt's remarks are clear and to the point. One cannot agree with Dr. Am brose when he says, to take one example, "that by no stretch of the imagination can one say that the right superior rectus takes the eye 'up' and 'in' as is described and pic tured in various textbooks." The "in" movement of the superior rectus is a secondary action associated with the "up" movement when the movement starts with the eye in the primary position. Here the visual axis is some 25 degrees nasal to the muscle plane of the superior rectus, as a result of which some secondary actions (duction and torsion) accompany the prin cipal "up" action. But the field of greatest "up" action of the superior rectus is when the eye is turned out, that is, when the visual axis approaches more the direction of the muscle plane. Here the principal "up" action becomes more and more marked and the sec ondary actions become less and less marked. There is thus no contradiction in the state ments that there is a secondary "in" action to the superior rectus, when the movement starts from a direction nasal to its muscle plane, and that its greatest "up" action is when the movement starts when the eye is turned outward, in the direction of its mus cle plane. But Dr. Hewitt's observations on "a some what paradoxial condition" are also open to
question. He says (page 1305, bottom) "when a movement is made from primary to an up and out position . . . the superior rectus must, of course, go into action to bring about this elevation. By acting the superior rectus creates a greater adducting pull than would this muscle when the eye was in the primary position. Or to express it differently while the superior rectus is exert ing a greater adducting pull the globe is being abducted and elevated." The catch here is that when the globe is being abducted and elevated the secondary adducting effect of the superior rectus be comes less and less marked and disappears entirely when the eye is abducted to 25 de grees from the primary position. The abduc tion is accomplished by the associated externus which, according to good authority, even comes into action to balance the adduct ing effect of the superior rectus when the eyes look straight up from the primary posi tion. A good deal of the confusion on ocular muscle action is due to the use of complicated and sometimes confusing diagrams. The whole subject becomes remarkably lucid and definite when the muscle action under all conditions is visualized and read off the double benzene ring muscle schema. (Signed) Joseph I. Pascal, New York.
BOOK
REVIEWS
: INJURIES. By Alston Callahan. Springfield, Illinois, Charles C Thomas, 1950. 217 pages, illustrated. Price: $11.50. This book is not, and the author did not intend it to be, an encyclopedic account of the methods of handling injuries of the eye and adnexa. It is a compendium of the au thor's experience in this field during his war time service and the five years since. As he states in his foreword, he found many methSURGERY OF THE EYE
310
ethical optometrists are keenly aware of their responsibilities toward these children. The visual-screening program has been in effect for two years now. Only approximate figures can be given at this time but the fol lowing statistics are interesting. Over 150,000 school children in the State of Illinois have, so far, been screened, about 15 percent of whom are shown to need eye care. Up to November 24, 1950, 47,318 chil dren have been screened in Chicago, about 12 percent of whom needed eye care. A con centrated study of 2,429 Chicago school chil dren who were visually handicapped showed that 1,534 of them went to ophthalmologists, 761 to optometrists, 56 to medical eye clinics, 22 to optometric clinics, and only 44 to de partment stores. The function of the Illinois Society for the Prevention of Blindness was to demon strate that such a program was highly impor tant for the welfare of our future citizens, easily carried out, relatively inexpensive, re quiring few numbers of easily trained test ers, and capable of drawing together ethical groups of professional people to do what was considered best for the handicapped child. The society has more than fulfilled its pilot mission. It is now time for the various boards of education to continue and to expand this most worthwhile venture. It is high time for other states to follow suit. Derrick Vail.
CORRESPONDENCE T H E CRISP-STINE TEST
Editor, American Journal of Ophthalmology: Stine, in recent articles in this JOURNAL (32:1128 [Aug.] 1949 and 33:1587 [Oct.] 1950), has well shown the remarkable pre cision that can be attained by the use of the astigmatic dial. In examinations conducted for the American Board of Ophthalmology
I found that when four candidates examined the refraction of the same eye the final cor rection obtained was different in every in stance. Evidently their methods did not as sure reproducible results. Only a few candi dates realized the importance of the astig matic dial and apparently most of them had little or no training in its use. Maddox used an angle of 50 degrees for locating the axis of lesser errors of astig matism, and 25 degrees for high errors. The angle of 60 degrees, used in the Lebensohn astigmometer, is wide enough to be prac tically useful in the Crisp-Stine test.Though the latter employs lines 45 degrees from the reference point, the 15-degree difference means an over-all reduction of 14 percent in effective power of both the applied and induced cross-cylinders but otherwise the same relations are maintained and the mathe matical difference that results is slight. Thus, at the wings of the arrow, the effective power of the 0.125D. applied crosscylinder is plus and minus 0.107D., respec tively. For l.OOD. astigmatism, with fivedegree error in axis, the induced cross-cyljnder effect at the arrow wings is 0.074D. Shifting the applied cross-cylinder from the neutralizing to the aggravating position changes the residual values from 0.033D. to 0.181D. The difference is 0.15D. as opposed to 0.17D. in the original Crisp-Stine test. The unmodified Crisp-Stine test can be used with the Lebensohn astigmometer by placing a small triangle of black Scotch tape at the midpoint of the arc subtending a clear quadrant. With the marker placed at the axis under consideration, the comparisons are then made between the arrow line and the plain line. The next edition of the Lebensohn chart will present this additional marker. A series of cases with various degrees of astigmatism tested by both methods showed a more definite response to one test over the other in even number. Evidently psychologic as well as mathematical factors determine the patient's reaction. When doubt exists, it
311
CORRESPONDENCE is advantageous to use both tests as one test then checks the other. (Signed) James E. Lebensohn, Chicago, Illinois. EXTRAOCULAR MUSCLES
Editor, American Journal of Ophthalmology: In his letter in the AMERICAN JOURNAL OF OPHTHALMOLOGY (33:1305 [Aug.] 1950), Dr. Robert S. Hewitt calls attention to some "erroneous deductions" made by Dr. Am brose in his article on the extraocular mus cles (Am. J. Ophth., 33:793 [May] 1950). Most of Dr. Hewitt's remarks are clear and to the point. One cannot agree with Dr. Am brose when he says, to take one example, "that by no stretch of the imagination can one say that the right superior rectus takes the eye 'up' and 'in' as is described and pic tured in various textbooks." The "in" movement of the superior rectus is a secondary action associated with the "up" movement when the movement starts with the eye in the primary position. Here the visual axis is some 25 degrees nasal to the muscle plane of the superior rectus, as a result of which some secondary actions (duction and torsion) accompany the prin cipal "up" action. But the field of greatest "up" action of the superior rectus is when the eye is turned out, that is, when the visual axis approaches more the direction of the muscle plane. Here the principal "up" action becomes more and more marked and the sec ondary actions become less and less marked. There is thus no contradiction in the state ments that there is a secondary "in" action to the superior rectus, when the movement starts from a direction nasal to its muscle plane, and that its greatest "up" action is when the movement starts when the eye is turned outward, in the direction of its mus cle plane. But Dr. Hewitt's observations on "a some what paradoxial condition" are also open to
question. He says (page 1305, bottom) "when a movement is made from primary to an up and out position . . . the superior rectus must, of course, go into action to bring about this elevation. By acting the superior rectus creates a greater adducting pull than would this muscle when the eye was in the primary position. Or to express it differently while the superior rectus is exert ing a greater adducting pull the globe is being abducted and elevated." The catch here is that when the globe is being abducted and elevated the secondary adducting effect of the superior rectus be comes less and less marked and disappears entirely when the eye is abducted to 25 de grees from the primary position. The abduc tion is accomplished by the associated externus which, according to good authority, even comes into action to balance the adduct ing effect of the superior rectus when the eyes look straight up from the primary posi tion. A good deal of the confusion on ocular muscle action is due to the use of complicated and sometimes confusing diagrams. The whole subject becomes remarkably lucid and definite when the muscle action under all conditions is visualized and read off the double benzene ring muscle schema. (Signed) Joseph I. Pascal, New York.
BOOK
REVIEWS
: INJURIES. By Alston Callahan. Springfield, Illinois, Charles C Thomas, 1950. 217 pages, illustrated. Price: $11.50. This book is not, and the author did not intend it to be, an encyclopedic account of the methods of handling injuries of the eye and adnexa. It is a compendium of the au thor's experience in this field during his war time service and the five years since. As he states in his foreword, he found many methSURGERY OF THE EYE