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.It might bedue, he said, to the accommodative action of the iris, and possibly also to alengthening of the visual axis through the action of the external muscles.3For nearly three-quarters of a century the opinions of these masters haveechoed through ophthalmological literature.Yet it is to-day a perfectly well-knownand undisputed fact that many persons, after the removal of the lens for cataract,are able to see perfectly at different distances without any change in theirglasses.Every ophthalmologist of any experience has seen cases of this kind,and many of them have been reported in the literature.In 1872, Professor Forster of Breslau, reported4 a1Absence of the lens.2On the Anomalies of Accommodation and Refraction of the Eye, p.320.3Archiv.f.Ophth., 1855, vol.ii, part 1, p.187 et seq.Albrecht von Graefe (1828-1870) was professor ofophthalmology in the University of Berlin, and is ranked with Donders and Arlt as one of the greatestophthalmologists of the nineteenth century.4 Klin.Montasbl.f.Augenh., Erlangen, 1872, vol.x, p.39, et seq. Not To Be Disputed 33series of twenty-two cases of apparent accommodation in eyes from which thelens had been removed for cataract.The subjects ranged in age from eleven toseventyfour years, and the younger ones had more accommodative power thanthe elder.A year later Woinow of Moscow1 reported eleven cases, the subjectsbeing from twelve to sixty years of age.In 1869 and 1870, respectively, Loringreported2 to the New York Ophthalmological Society and the AmericanOphthalmological Society the case of a young woman of eighteen who, withoutany change in her glasses, read the twenty line on the Snellen test card at twentyfeet and also read diamond type at from five inches to twenty.On October 8,1894, a patient of Dr.A.E.Davis who appeared to accommodate perfectlywithout a lens consented to go before the New York Ophthalmological Society."The members," Dr.Davis reports,3 "were divided in their opinion as to how thepatient was able to accommodate for the nearpoint with his distance glasses on";but the fact that he could see at this point without any change in his glasses wasnot to be disputed.The patient was a chef, forty-two years old, and on January 27, 1894, Dr.Davis had removed a black cataract from his right eye, supplying him at thesame time with the usual outfit of glasses, one to replace the lens, for distantvision, and a stronger one for reading.In October he returned, not because hiseye was not doing well, but because he was afraid he might be "straining" it.Hehad discarded his reading glasses after a few weeks, and had since been usingonly his distance glasses.Dr.1Archiv.f.Ophth., 1873, vol.xix, part 3, p.107.2Flint: Physiology of Man, 1875, vol.v, pp.110-111.3Davis: Accommodation in the Lensless Eye, Reports of the Manhattan Eye and Ear Hospital, Jan., 1895.Thearticle gives a review of the whole subject.34 Accepted Theory of AccommodationDavis doubted the truth of his statements, never having seen such a case before,but found them, upon investigation, to be quite correct.With his lensless eye anda convex glass of eleven and a half diopters, the patient read the ten line on thetest card at twenty feet, and with the same glass, and without any change in itsposition, he read fine print at from fourteen to eighteen inches Dr.Davis thenpresented the case to the Ophthalmological Society but, as has been stated, heobtained no light from that source.Four months later, February 4, 1895, thepatient still read 20/10 at the distance and his range at the near-point hadincreased so that he read diamond type at from eight to twenty-two and a halfinches.Dr.Davis subjected him to numerous tests, and though unable to find anyexplanation for his strange performances, he made some interestingobservations.The results of the tests by which Donders satisfied himself that thelensless eye possessed no accommodative power were quite different fromthose reported by the Dutch authority, and Dr.Davis therefore concluded thatthese tests were "wholly inadequate to decide the question at issue." Duringaccommodation the ophthalmometer1 showed that the corneal curvature waschanged and that the cornea moved forward a little.Under scopolamine, a drugsometimes used instead of atropine to paralyze the ciliary muscle (1/10 per centsolution every five minutes for thirty-five minutes, followed by a wait of half anhour), these changes took place as before; they also took place when the lidswere held up.With the possible influence of lid pressure and of the ciliary muscleeliminated, therefore, Dr.Davis felt himself bound to conclude that the changes"must1An instrument for measuring the curvature of the cornea.Another Puzzling Case 35have been produced by the action of the external muscles." Under scopolamine,also, the man's accommodation was only slightly affected, the range at thenearpoint being reduced only two and a half inches.The ophthalmometer further showed the patient to have absolutely noastigmatism.It had showed the same thing about three months after theoperation, but three and a half weeks after it he had four and a half diopters.Seeking further light upon the subject Dr.Davis now subjected to similar testsa case which had previously been reported by Webster in the "Archives ofPediatrics." 1 The patient had been brought to -Dr.Webster at the age of ten withdouble congenital cataract.The left lens had been absorbed as the result ofsuccessive needlings, leaving only an opaque membrane, the lens capsule, whilethe right, which had not been interfered with, was sufficiently transparent aroundthe edge to admit of useful vision.Dr.Webster made an opening in themembrane filling the pupil of the left eye, after which the vision of this eye, with aglass to replace the lens, was about equal to the vision of the right eye without aglass.For this reason Dr.Webster did not think it necessary to give the patientdistance glasses, and supplied him with reading glasses only plane glass forthe-right eye and convex 16D for the left [ Pobierz całość w formacie PDF ]