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The prolonged occlusion test
CORRESPONDENCE
this test who considered the gauze patch an improvement over Marlow's opaque lens. . . . Marlow himself gave support (the italics are mine) to this more effective method of producing dis sociation by failure to criticise this point in his discussion of C. S. O'Brien's pa per'. "This carries implications untrue in two particulars. In the first place that I have used a gauze patch and second ly that I support its use. I have never used a gauze patch and consequently have no experience on which to base an opinion. On general principles I do not think it desirable for reasons obvi ous to any intelligent and experienced ophthalmologist. In the next place I have said nothing about such a method either one way or the other. In other words, Dr. Abraham has twisted what I did not say into an opinion supporting what he considers the better method. On the other hand in my monograph on the occlusion test I have specifically stated that I have found a ground glass to be quite efficient although in some cases that it is pleasanter for the pa tient to have a black patch or to paste a piece of dark paper over the back of the lens. Again in a paper on the "Tech nique of the Occlusion Test" (A.J.O., April 1932), I stated the same thing, that, as a matter of fact, a ground glass is quite efficient and much less con spicuous than any other device. "If Dr. Abraham had paid more care ful attention to what I have said on thé subject and not drawn a positive con clusion from a negative basis he would have avoided an untenable position. As it is, he admits coming to very impor tant conclusions from very inadequate data. For instance, in the small number of cases he examined the period of oc clusion averaged twenty-three hours. A week's occlusion at least is necessary for reliable conclusions. "In the discussion referred to by Dr. Abraham I said, Ί doubt the value of such short tests as Dr. O'Brien de
357
scribes and I fear that if these short tests do not bring the prolonged oc clusion test into disrepute they will at any rate greatly lower its value'. "The papers of Abraham and Beisbarth seem to justify this doubt. "Further comment is unnecessary." (Signed) F. W. Marlów. March 13, 1933. Editor, American Journal of Ophthalmology. Dear Sir : Because of the association of Rio Hortega's name with microglia and oli godendroglia in general, I gave Rio Hortega the credit for their discovery in the retina and optic nerve in my "Notes". Dr. Lopez'Enriquez of Madrid puts me right on the subject in the fol lowing letter, translated from the Span ish: "I have read with great pleasure your 'Notes on history of ophthalmology in Spain', published in v. 15, November 1932, of the Amer. Jour, of Ophth. "As a Spaniard I am very much grati. fied with the attitude of your paper, but I take the liberty of calling your atten tion to the paragraph in which you say 'Rio Hortega, the discoverer of phagocytic microglia and oligodendroglia in retina and optic nerve'. Since it is a matter of actual facts of our own days, I am interested in informing you about the subject. "My dear teacher Rio Hortega is en titled to the honor of having discovered and sagaciously interpreted the microg lia and oligodendroglia in the brain and spinal cord. The discovery of the same elements in the retina and optic path ways was made by me in 1926. "Please consider these lines in the light of a simple desire to record the fact. Yours, etc. L. Enriques." In the light of the above letter, a cor rection in the Journal is in order. Yours very sincerely, (Signed) M. Davidson.
this test who considered the gauze patch an improvement over Marlow's opaque lens. . . . Marlow himself gave support (the italics are mine) to this more effective method of producing dis sociation by failure to criticise this point in his discussion of C. S. O'Brien's pa per'. "This carries implications untrue in two particulars. In the first place that I have used a gauze patch and second ly that I support its use. I have never used a gauze patch and consequently have no experience on which to base an opinion. On general principles I do not think it desirable for reasons obvi ous to any intelligent and experienced ophthalmologist. In the next place I have said nothing about such a method either one way or the other. In other words, Dr. Abraham has twisted what I did not say into an opinion supporting what he considers the better method. On the other hand in my monograph on the occlusion test I have specifically stated that I have found a ground glass to be quite efficient although in some cases that it is pleasanter for the pa tient to have a black patch or to paste a piece of dark paper over the back of the lens. Again in a paper on the "Tech nique of the Occlusion Test" (A.J.O., April 1932), I stated the same thing, that, as a matter of fact, a ground glass is quite efficient and much less con spicuous than any other device. "If Dr. Abraham had paid more care ful attention to what I have said on thé subject and not drawn a positive con clusion from a negative basis he would have avoided an untenable position. As it is, he admits coming to very impor tant conclusions from very inadequate data. For instance, in the small number of cases he examined the period of oc clusion averaged twenty-three hours. A week's occlusion at least is necessary for reliable conclusions. "In the discussion referred to by Dr. Abraham I said, Ί doubt the value of such short tests as Dr. O'Brien de
357
scribes and I fear that if these short tests do not bring the prolonged oc clusion test into disrepute they will at any rate greatly lower its value'. "The papers of Abraham and Beisbarth seem to justify this doubt. "Further comment is unnecessary." (Signed) F. W. Marlów. March 13, 1933. Editor, American Journal of Ophthalmology. Dear Sir : Because of the association of Rio Hortega's name with microglia and oli godendroglia in general, I gave Rio Hortega the credit for their discovery in the retina and optic nerve in my "Notes". Dr. Lopez'Enriquez of Madrid puts me right on the subject in the fol lowing letter, translated from the Span ish: "I have read with great pleasure your 'Notes on history of ophthalmology in Spain', published in v. 15, November 1932, of the Amer. Jour, of Ophth. "As a Spaniard I am very much grati. fied with the attitude of your paper, but I take the liberty of calling your atten tion to the paragraph in which you say 'Rio Hortega, the discoverer of phagocytic microglia and oligodendroglia in retina and optic nerve'. Since it is a matter of actual facts of our own days, I am interested in informing you about the subject. "My dear teacher Rio Hortega is en titled to the honor of having discovered and sagaciously interpreted the microg lia and oligodendroglia in the brain and spinal cord. The discovery of the same elements in the retina and optic path ways was made by me in 1926. "Please consider these lines in the light of a simple desire to record the fact. Yours, etc. L. Enriques." In the light of the above letter, a cor rection in the Journal is in order. Yours very sincerely, (Signed) M. Davidson.