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A nineteenth century view of the optic commissure
SURVEY OF OPHTHALMOLOGY@ VOLUME 32 NUMBER 3 NOVEMBER-DECEMBER1987 l
HISTORY
l
OF OPHTHALMOLOGY
DANIEL ALBERT, EDITOR
A Nineteenth
Century View of the Optic Commissure
THOMAS M. REYNOLDS, M.D.
Department of Ophthalmology, University of Tennessee College of Medicine, Chattanooga, Tennessee
Abstract. Historically, ophthalmologists and anatomists have been intrigued by the optic nerve and its decussation. Isaac Newton was the first to describe and suggest the significance of the chiasmal crossing, while W.H. Wollaston defined the importance of hemiretinal differentiation in 1824. However, at that time, the vertical meridian separating nasal from temporal retina was believed to be located at the optic papillae. This theory was disproved in 1870 by two Philadelphia ophthalmologists, who demonstrated and documented the vertical meridian at the macula during their examination of an injured Civil War soldier. (Surv Ophtbalmol32:2 14-2 16,1987)
Key words.
hemiretinal differentiation
l
macula
l
optic chiasm
who died of a thalamic tumor which produced an intermittent homonymous hemianopsia,3 vividly described his own symptoms of “half-blindness.“7 At that time, the vertical meridian separating temporal from nasal retina was thought to be occupied by the optic nerve, despite the knowledge of the blind spot in the visual field by Mariotte.3,5 In 1870, two Philadelphia ophthalmologists, Drs. W.W. Keen and William Thomson, apparently were the first to discover the vertical demarcation of the retina at the fovea with their detailed examination of a patient injured in the Civil War. Private Patrick Hughes, an Irish immigrant, was wounded while fighting in Antietam, New York. He sustained a blow from a musketball to the left occiput during battle in September, 1862 (Fig. 1). On December 20th, 1870, Drs. Keen and Thomson examined Hughes eight years after his injury. Among other things, Hughes complained that “the sight of his right eye, he (thought was) poor;” however, “whiskey (affected) him as usual (and his) sexual power (was) undiminished.“5 Upon testing of the field of vision, Keen and Thomson precisely localized the hemiretinal verti-
Since the days of Galen the optic nerve and its chiasm have been the source of fascination to many ophthalmologists, anatomists, and physicists. It was originally believed that the optic nerves were hollow tubes carrying morbid humours from the brain.2 Observations by William Briggs, an English physician, advanced knowledge of the general arrangement of the optic nerve fibers. Briggs, in 1685, described the “optic papilla” as the point of convergence for retinal fibers which then coursed down the optic nerve. However, he felt the nerve fibers were uncrossed at the chiasm and Newton later suggested to Briggs that a decussation would explain the facts of binocular vision.3 The macula was described by Soemmerring of Frankfurt in 1799. He believed the fovea to be responsible for Mariotte’s blind spot and viewed the structure as a “clearly defined yellow border . . . devoid ofall blood vessels. . . that served as a wastepipe to carry away excess of light which might cause harm or pain.“3 It was left to Wollaston in 1824 to realize the significance of hemiretinal differentiation in homonymous hemianopsias. 3,7 Interestingly, Wollaston, 214
OPTIC
COMMISSURE
Fig. 2. A replica of Keen & Thomson’s original drawing of the proposed crossing of the optic chiasm. Where C and C’ denote the macula, a represents the left temporal retinal fibers, b represents the right nasal retinal fibers, and a and b form the left optic tract. (From The Medical and Surgical History of the War of the Rebellion, 1875.) Fig. 1. A drawing from the original photograph of Private Hughes eight years after the injury. (From T7zeMedical and Surgical Historv of the War of the Rebellion, 1875).
cal meridian at the macula lutea rather than the pars opticus (optic nerve).* They found the visual field to be “divided for each eye by a line passing through its centre, in the vertical direction - total blindness to the right and perfect vision to the left, of this line,“5 or in modern terms, a right homonymous hemianopsia. Using a “point of light” for fixation purposes at a distance of eight feet, they found that “when, for example, the right eye is fixed . . . a second point of light is lost to view when it is moved one inch towards the right.” Further “with the right eye it is not possible to determine the spot of Mariotte - that is, the blind spot in the field corresponding to the entrance of the optic nerve” in the nasal retina - “since the insensitiveness of the retina in [the right] eye commences at the inner margin of the macula lutea, and extends to the entire inner half of the retina.” (Fig. 2) Concerning the left eye, “that portion of the retina between the optic nerve entrance and the macula is found normal in sensitiveness; since, when at four *The article by Keen and Thomson contained a well-referenced review of the current theories concerning the optic chiasm, including views held by Von Graefe, Airy and Wollaston.
feet the left eye is fixed upon a point of light, a second light is clearly perceived as it is moved towards the left until it has reached a point nine inches to the left, where it is lost, to reappear at a point thirteen inches from the first light. Beyond this point the field has normal extent.” Thus, Keen and Thomson correctly described the normal occupation of the blind spot temporal to fixation in the visual field by approximately fifteen degrees - or nine to thirteen inches at four feet in their exam. The existence of a semi-decussation of the optic nerve in the late 1800’s was well known. Keen and Thomson referenced Wollaston’s paper and stated that Von Graefe “[assented] cordially to Wollaston’s view, admitting that he [proposed] nothing new.” Airy’s support of this theory concerning the decussation was also referenced. Interestingly, Airy’s paper “On a Distinct Form of Transient Hemiopsia” dealt with his own descriptions of the classic migraine headache fortification scotoma and its associated transient obscuration of vision.’ With the semi-decussation of the nerve at the chiasm being admitted, the purpose of Keen and Thomson’s detailed visual field study was to point out the “rigid optical examination of the region between the porus optics and the macula lutea.” Beyond the optic tracts, however, Keen and Thomson
216
Surv Ophthalmol
32(3) November-December
had little to add; “as to the cerebral seat of the sense of vision, the amount and depth of the injury to the brain are too uncertain, perhaps, to warrant us in venturing on any speculations as to its locality.” Keen and Thomson’s findings elucidated what they termed “the probable anatomy of the optic (Fig. 2) portrays an commissure. ” Their diagram accurate representation of retinal differentiation and the optic nerve decussation in the chiasm. It is one of the first, if not the first, published accounts of the correct anatomical relationship between nasal and temporal retinal fibers and the optic chiasm. Hughes’ case report was published in the first surgical volume of The Medical and Surgical History of the War of the Rebellion,6 written by Dr. George A. Otis under the direction of the Surgeon General of the United States Army, Joseph K. Barnes. The report included an annexed account of a publication of Keen and Thomson from the Photographic Review of Medicine and Surgery in 1871.
REYNOLDS
1987
Acknowledgment The author gratefully acknowledges the staff at the Erlanger Medical Center Library for their diligent preservation of The Medical and Surgical History of the War of the Rebellion.
References 1. Airy H: On a distinct form of transient hemiopsia: Nature: 440, 1870 2. Chance B: Ophthalmology. New York, Hafner Publishing Company, 1962, p 12 3. Duke-Elder S, Wylar KC: System of Ophthalmology, Vol. 2. St Louis, CV Mosby, 1961, ed 1, pp 67, 274, 647-648 4. Hirschberg J: The History of Ophthalmology in Antiqui@ (Translated by FC Blodi) Bonn, Verlaz JP Wayenborgh, 1982, p 179 5. Keen WW, Thomson W: Gunshot wound of the brain followed by fungus cerebri, and recovery with hemiopsia. Photographic Review of Medicine and Surgery I, Number 3, 25-30, 1871 6. Otis GA: The Medical and Surgical History of the War of the Rebellion, Vol 2, Part 1. 1875, p 207 7. Wollaston WH: On semi-decussation of the optic nerves. Philos Tram: 222, 1824 Reprints should be addressed to Dr. Thomas M. Reynolds, Miller Eye Center, 975 East Third Street, Suite 206, Chattanooga, Tennessee 37403.
HISTORY
l
OF OPHTHALMOLOGY
DANIEL ALBERT, EDITOR
A Nineteenth
Century View of the Optic Commissure
THOMAS M. REYNOLDS, M.D.
Department of Ophthalmology, University of Tennessee College of Medicine, Chattanooga, Tennessee
Abstract. Historically, ophthalmologists and anatomists have been intrigued by the optic nerve and its decussation. Isaac Newton was the first to describe and suggest the significance of the chiasmal crossing, while W.H. Wollaston defined the importance of hemiretinal differentiation in 1824. However, at that time, the vertical meridian separating nasal from temporal retina was believed to be located at the optic papillae. This theory was disproved in 1870 by two Philadelphia ophthalmologists, who demonstrated and documented the vertical meridian at the macula during their examination of an injured Civil War soldier. (Surv Ophtbalmol32:2 14-2 16,1987)
Key words.
hemiretinal differentiation
l
macula
l
optic chiasm
who died of a thalamic tumor which produced an intermittent homonymous hemianopsia,3 vividly described his own symptoms of “half-blindness.“7 At that time, the vertical meridian separating temporal from nasal retina was thought to be occupied by the optic nerve, despite the knowledge of the blind spot in the visual field by Mariotte.3,5 In 1870, two Philadelphia ophthalmologists, Drs. W.W. Keen and William Thomson, apparently were the first to discover the vertical demarcation of the retina at the fovea with their detailed examination of a patient injured in the Civil War. Private Patrick Hughes, an Irish immigrant, was wounded while fighting in Antietam, New York. He sustained a blow from a musketball to the left occiput during battle in September, 1862 (Fig. 1). On December 20th, 1870, Drs. Keen and Thomson examined Hughes eight years after his injury. Among other things, Hughes complained that “the sight of his right eye, he (thought was) poor;” however, “whiskey (affected) him as usual (and his) sexual power (was) undiminished.“5 Upon testing of the field of vision, Keen and Thomson precisely localized the hemiretinal verti-
Since the days of Galen the optic nerve and its chiasm have been the source of fascination to many ophthalmologists, anatomists, and physicists. It was originally believed that the optic nerves were hollow tubes carrying morbid humours from the brain.2 Observations by William Briggs, an English physician, advanced knowledge of the general arrangement of the optic nerve fibers. Briggs, in 1685, described the “optic papilla” as the point of convergence for retinal fibers which then coursed down the optic nerve. However, he felt the nerve fibers were uncrossed at the chiasm and Newton later suggested to Briggs that a decussation would explain the facts of binocular vision.3 The macula was described by Soemmerring of Frankfurt in 1799. He believed the fovea to be responsible for Mariotte’s blind spot and viewed the structure as a “clearly defined yellow border . . . devoid ofall blood vessels. . . that served as a wastepipe to carry away excess of light which might cause harm or pain.“3 It was left to Wollaston in 1824 to realize the significance of hemiretinal differentiation in homonymous hemianopsias. 3,7 Interestingly, Wollaston, 214
OPTIC
COMMISSURE
Fig. 2. A replica of Keen & Thomson’s original drawing of the proposed crossing of the optic chiasm. Where C and C’ denote the macula, a represents the left temporal retinal fibers, b represents the right nasal retinal fibers, and a and b form the left optic tract. (From The Medical and Surgical History of the War of the Rebellion, 1875.) Fig. 1. A drawing from the original photograph of Private Hughes eight years after the injury. (From T7zeMedical and Surgical Historv of the War of the Rebellion, 1875).
cal meridian at the macula lutea rather than the pars opticus (optic nerve).* They found the visual field to be “divided for each eye by a line passing through its centre, in the vertical direction - total blindness to the right and perfect vision to the left, of this line,“5 or in modern terms, a right homonymous hemianopsia. Using a “point of light” for fixation purposes at a distance of eight feet, they found that “when, for example, the right eye is fixed . . . a second point of light is lost to view when it is moved one inch towards the right.” Further “with the right eye it is not possible to determine the spot of Mariotte - that is, the blind spot in the field corresponding to the entrance of the optic nerve” in the nasal retina - “since the insensitiveness of the retina in [the right] eye commences at the inner margin of the macula lutea, and extends to the entire inner half of the retina.” (Fig. 2) Concerning the left eye, “that portion of the retina between the optic nerve entrance and the macula is found normal in sensitiveness; since, when at four *The article by Keen and Thomson contained a well-referenced review of the current theories concerning the optic chiasm, including views held by Von Graefe, Airy and Wollaston.
feet the left eye is fixed upon a point of light, a second light is clearly perceived as it is moved towards the left until it has reached a point nine inches to the left, where it is lost, to reappear at a point thirteen inches from the first light. Beyond this point the field has normal extent.” Thus, Keen and Thomson correctly described the normal occupation of the blind spot temporal to fixation in the visual field by approximately fifteen degrees - or nine to thirteen inches at four feet in their exam. The existence of a semi-decussation of the optic nerve in the late 1800’s was well known. Keen and Thomson referenced Wollaston’s paper and stated that Von Graefe “[assented] cordially to Wollaston’s view, admitting that he [proposed] nothing new.” Airy’s support of this theory concerning the decussation was also referenced. Interestingly, Airy’s paper “On a Distinct Form of Transient Hemiopsia” dealt with his own descriptions of the classic migraine headache fortification scotoma and its associated transient obscuration of vision.’ With the semi-decussation of the nerve at the chiasm being admitted, the purpose of Keen and Thomson’s detailed visual field study was to point out the “rigid optical examination of the region between the porus optics and the macula lutea.” Beyond the optic tracts, however, Keen and Thomson
216
Surv Ophthalmol
32(3) November-December
had little to add; “as to the cerebral seat of the sense of vision, the amount and depth of the injury to the brain are too uncertain, perhaps, to warrant us in venturing on any speculations as to its locality.” Keen and Thomson’s findings elucidated what they termed “the probable anatomy of the optic (Fig. 2) portrays an commissure. ” Their diagram accurate representation of retinal differentiation and the optic nerve decussation in the chiasm. It is one of the first, if not the first, published accounts of the correct anatomical relationship between nasal and temporal retinal fibers and the optic chiasm. Hughes’ case report was published in the first surgical volume of The Medical and Surgical History of the War of the Rebellion,6 written by Dr. George A. Otis under the direction of the Surgeon General of the United States Army, Joseph K. Barnes. The report included an annexed account of a publication of Keen and Thomson from the Photographic Review of Medicine and Surgery in 1871.
REYNOLDS
1987
Acknowledgment The author gratefully acknowledges the staff at the Erlanger Medical Center Library for their diligent preservation of The Medical and Surgical History of the War of the Rebellion.
References 1. Airy H: On a distinct form of transient hemiopsia: Nature: 440, 1870 2. Chance B: Ophthalmology. New York, Hafner Publishing Company, 1962, p 12 3. Duke-Elder S, Wylar KC: System of Ophthalmology, Vol. 2. St Louis, CV Mosby, 1961, ed 1, pp 67, 274, 647-648 4. Hirschberg J: The History of Ophthalmology in Antiqui@ (Translated by FC Blodi) Bonn, Verlaz JP Wayenborgh, 1982, p 179 5. Keen WW, Thomson W: Gunshot wound of the brain followed by fungus cerebri, and recovery with hemiopsia. Photographic Review of Medicine and Surgery I, Number 3, 25-30, 1871 6. Otis GA: The Medical and Surgical History of the War of the Rebellion, Vol 2, Part 1. 1875, p 207 7. Wollaston WH: On semi-decussation of the optic nerves. Philos Tram: 222, 1824 Reprints should be addressed to Dr. Thomas M. Reynolds, Miller Eye Center, 975 East Third Street, Suite 206, Chattanooga, Tennessee 37403.