LETTERS TO THE JOURNAL Inferior Rectus Muscle Palsy After Retrobulbar Anesthesia for Cataract Surgery
tion, prostatitis, and medically controlled hypertension. The patient stated that the retrobulbar injection in his right orbit was extremely painful. Immediately after surgery he felt numbness of his right infraorbital region and noted blepharoptosis of the right upper eyelid. After two weeks the blepharoptosis subsided, and the patient noticed diplopia and a constant hypertropia of the right eye. According to the operative report, 6 ml of 0.75% bupivacaine hydrochloride was injected retrobulbarly one hour before the surgery. The needle was inserted into the inferotemporal right lower eyelid, pointing to the apex of the orbit, while the patient was directed to elevate and adduct the eye. A Honan balloon was applied to decrease the intraocular pressure. A 7-0 silk bridle suture was placed through the insertion of the superior rectus muscle. The cataract surgery was uncomplicated, and the pterygia excision proceeded without difficulty. Upon examination, best-corrected visual acuity was R.E.: 20/30 with refraction of -3.00 + 0.50 x 125 and L.E.: 20/20 with refraction of plano + 0.75 x 155. The right pupil was 4 mm in size, moderately reactive to light, and moderately reactive to near with no afferent pupillary defect; the left pupil was 3 mm in size, markedly reactive to light, and moderately reactive to near with no afferent pupillary defect. Slit-lamp examination was consistent with bilateral pseudophakia. Intraocular pressure was 10 mm Hg in each eye, and the visual fields were within normal limits to three-step con-
]an-Tjeerd H. N. de Faber, M.D., and Gunter K. von Noorden, M.D. Cullen Eye Institute, Baylor College of Medicine, and Ophthalmology Service, Texas Children's Hospital. This study was supported in part by a Nato-Science Fellowship from The Netherlands Organization for Scientific Research, Stichting HOF, The Netherlands (Dr. de Faber), and the National Children's Eye Care Foundation.
Inquiries to Gunter K. von Noorden, M.D., Ophthalmology Service, Texas Children's Hospital, Box 20269, Houston, TX 77225.
Isolated inferior rectus muscle paralysis is an infrequently reported eye muscle problem. The cause is congenital, traumatic, myasthenic, vascular, and idiopathic.' We treated a patient with iatrogenic inferior rectus muscle paresis after cataract surgery. A 74-year-old man was referred to us because of constant diplopia after extracapsular cataract surgery in the right eye under local retrobulbar anesthesia with implantation of an intraocular lens four months previously. At the same time, medial and lateral pterygia were excised from the right eye. His left eye was pseudophakic after an uncomplicated extracapsular cataract extraction with implantation of an intraocular lens under retrobulbar anesthesia and argon laser photocoagulation of an asymptomatic peripheral retinal break two years previously. His medical history included a myocardial infarc-
THE JOURNAL welcomes letters that describe unusual clinical or pathologic findings, experimental results, and new instruments or techniques. The title and the names of all authors appear in the Table of Contents and are retrievable through the Index Medicus and other standard indexing services. Letters must not duplicate data previously published or submitted for publication. Each letter must be accompanied by a signed disclosure statement and copyright transfer agreement published in each issue of THE JOURNAL. Letters must be typewritten, double-spaced, on 8 1/2 x H-Inch bond paper with 1 l/2-inch margins on all four sides. (See Instructions to Authors.) An original and two copies of the typescript and figures must be sent. The letters should not exceed 500 words of text. A maximum of two black-and-white figures may be used; they should be cropped or reducible to a width of 3 inches (one column). Color figures cannot be used. References should be limited to five. Letters may be referred to outside editorial referees for evaluation or may be reviewed by members of the Editorial Board. All letters are published promptly after acceptance. Authors do not receive galley proofs but if the editorial changes are extensive, the corrected typescript is submitted to them for approval. These instructions markedly limit the opportunity for an extended discussion or review. Therefore, THE JOURNAL does not publish correspondence concerning previously published letters. 209
210
AMERICAN JOURNAL OF OPHTHALMOLOGY
frontation. Results of ophthalmoscopy were normal in the right eye and showed an old peripheral retinal break surrounded by photocoagulation scars in the left eye. Medical examination, including thyroid studies and neurologic examination, demonstrated no abnormalities. Orthoptic examination showed an exotropia of 10 prism diopters with a right hypertropia of 40 prism diopters at distance and an exotropia of 16 prism diopters with a right hypertropia of 50 prism diopters at near as determined with the prism cover test in primary position while the patient was wearing his spectacles. The right hypertropia was highly incomitant and measured up to 50 prism diopters with the eyes elevated in right gaze contrasted with 25 prism diopters with the eyes depressed in left gaze. Ductions and versions showed an excess of elevation and restriction of depression of the right eye in primary position and abduction (Figure). The Bielschowsky head tilt test was unequivocal. The forced duction test showed restriction on attempts to depress the right eye. The right eye showed a floating saccade in the direction of action of the right inferior rectus muscle, which clearly indicated a palsy of this muscle. We concluded that this patient had a right inferior rectus muscle palsy with rapid onset of secondary contracture of the unopposed ipsilateral superior rectus muscle. We suspected injury of the inferior rectus muscle from the retrobulbar injection but considered also fibro-
August, 1991
sis of the superior rectus muscle from a bridlesuture injury as possible causes. Six months after the cataract extraction, the patient underwent surgical correction of his right hypertropia. During surgery the superior rectus muscle was inspected up to 12 mm posterior of its insertion and found to be normal without any scarring or other evidence of an intramuscular hemorrhage from the bridle suture. The forced duction test became negative after the superior rectus muscle had been detached from its original insertion, which indicated that this muscle had become tight after paralysis of its antagonist. Surgery consisted of a 7-mm recession of the right superior rectus muscle with a conjunctival recession, combined with a 4.5-mm resection of the right inferior rectus muscle. Three months postoperatively the patient showed a right hypertropia of only 5 prism diopters at near and distance, which increased to 10 prism diopters in right gaze. The patient was able to fuse with a slight chin elevation and had no diplopia in primary position. Transient strabismus and blepharoptosis are fairly common and benign complications of retrobulbar anesthesia. Permanent strabismus, however, is rare." Inferior rectus muscle paralysis in our patient can be explained by either direct trauma from the injection needle to the nerve of the inferior rectus muscle.v' which enters the muscle in its posterior one third, or by myotoxicity of bupivacaine hydrochloride."
Figure (de Faber and von Noorden). Versions in the nine diagnostic positions show an incomitant right hypertropia of 50 prism diopters in right gaze with the eyes elevated contrasted with only 25 prism diopters in left gaze with the eyes depressed.
Vol. 112, No.2
Letters to The Journal
References 1. von Noorden, G. K., and Hansell, R.: Clinical characteristics and treatment of isolated inferior rectus paralysis. Ophthalmology 98:253, 1991. 2. Hamed, L. H.: Strabismus presenting after cataract surgery. Ophthalmology 98:247, 1991. 3. Avilla, C. W.: Acquired strabismus in adulthood. 21st Annual Richard G. Scobee Lecture 1990. Am. Orthop. J. In press. 4. Catalano, R. A, Nelson, L. B., Calhoun, J. H., Schatz, N. J., and Harley, R. D.: Persistent strabismus presenting after cataract surgery. Ophthalmology 94:491, 1987. 5. Rainin, E. A., and Carlson, B. M.: Postoperative diplopia and ptosis. A clinical hypothesis based on the myotoxicity of local anesthetics. Arch. Ophthalmol. 103:1337, 1985.
Measurement of the Radius of Corneal Curvature With the Maloney Surgical Keratometer Hiromasa Igarashi, M.D.,
[un Akiba, M.D.,
Hiroyuki Hirokawa, M.D., and Akitoshi Yoshida, M.D.
Department of Ophthalmology, Asahikawa Medical College. Inquiries to Hiromasa Igarashi, M.D., Department of Ophthalmology, Asahikawa Medical College, 4-5, Nishikagura, Asahikawa 078, Japan. Because measuring the radius of corneal curvature in infants is sometimes difficult using an ophthalmometer and a photokeratometer, we sought an alternate method for determining the base curve when prescribing contact lenses for infants after congenital cataract surgery. The surgical keratometer developed by Maloney (Katena Products Inc., Denville, NJ) can project Placido's disk onto the cornea during surgery; the imagery then can be recorded on film or videotape.P If the image of Placido's disk can be analyzed in the same way as with the photokeratometer.v' the radius of corneal curvature can be determined without using an ophthalmometer or photokeratometer. We used a photokeratometer-based system to analyze Placido's disk projected by the surgical keratometer onto the corneas of 39 eyes of 20 healthy adults (age range, 19 to 26 years; average age, 22.3
211
years). We then evaluated the accuracy of this method. To obtain control data, the radii of corneal curvature also were measured in the same 39 eyes with an ophthalmometer. With the subjects in the supine position, 0.4% benoxinate hydrochloride drops were administered, and a Barraquer speculum was fitted. The surgical microscope was adjusted so that the cornea was centered in the visual field. The surgical keratometer that projected Placido's disk also was maintained in a fixed position over the cornea. When the disk projection was uniformly positioned over the corneal surface, the area was photographed (Figure). The projections of Placido's disk were traced on the photographs with black-and-white outliner pens, and an analysis was performed with the photokeratorneter-based corneal shape analysis unit and the PHORM 100 corneal shape analysis software system (Suncontact, Kyoto, Japan). The results then were compared with those obtained using the ophthalmometer. In 15 of the 39 subjects (38%), deviation in the value of the average radius of curvature was within 0.1 mm; in 27 subjects (69%), deviation was within 0.2 mm; and in 31 subjects (79%), deviation was within 0.3 mm. In 14 of the 39 subjects (36%), the error range of the flattest principal meridian was within 0.1 mm; in 25 subjects (64%), the range was within 0.2 mm: and in 31 subjects (79%), the range was within 0.3 mm. In cases in which the degree of corneal astigmatism was 1 diopter or more, the deviation tended to become larger. When the astigmatism was 1 diopter or less, however, the range of deviation was within 0.3 mm in 28 of 30 eyes (93%). Thus, based on these results our
Figure (Igarashi and associates). Placido's disk projected by the surgical keratometer.
tion, prostatitis, and medically controlled hypertension. The patient stated that the retrobulbar injection in his right orbit was extremely painful. Immediately after surgery he felt numbness of his right infraorbital region and noted blepharoptosis of the right upper eyelid. After two weeks the blepharoptosis subsided, and the patient noticed diplopia and a constant hypertropia of the right eye. According to the operative report, 6 ml of 0.75% bupivacaine hydrochloride was injected retrobulbarly one hour before the surgery. The needle was inserted into the inferotemporal right lower eyelid, pointing to the apex of the orbit, while the patient was directed to elevate and adduct the eye. A Honan balloon was applied to decrease the intraocular pressure. A 7-0 silk bridle suture was placed through the insertion of the superior rectus muscle. The cataract surgery was uncomplicated, and the pterygia excision proceeded without difficulty. Upon examination, best-corrected visual acuity was R.E.: 20/30 with refraction of -3.00 + 0.50 x 125 and L.E.: 20/20 with refraction of plano + 0.75 x 155. The right pupil was 4 mm in size, moderately reactive to light, and moderately reactive to near with no afferent pupillary defect; the left pupil was 3 mm in size, markedly reactive to light, and moderately reactive to near with no afferent pupillary defect. Slit-lamp examination was consistent with bilateral pseudophakia. Intraocular pressure was 10 mm Hg in each eye, and the visual fields were within normal limits to three-step con-
]an-Tjeerd H. N. de Faber, M.D., and Gunter K. von Noorden, M.D. Cullen Eye Institute, Baylor College of Medicine, and Ophthalmology Service, Texas Children's Hospital. This study was supported in part by a Nato-Science Fellowship from The Netherlands Organization for Scientific Research, Stichting HOF, The Netherlands (Dr. de Faber), and the National Children's Eye Care Foundation.
Inquiries to Gunter K. von Noorden, M.D., Ophthalmology Service, Texas Children's Hospital, Box 20269, Houston, TX 77225.
Isolated inferior rectus muscle paralysis is an infrequently reported eye muscle problem. The cause is congenital, traumatic, myasthenic, vascular, and idiopathic.' We treated a patient with iatrogenic inferior rectus muscle paresis after cataract surgery. A 74-year-old man was referred to us because of constant diplopia after extracapsular cataract surgery in the right eye under local retrobulbar anesthesia with implantation of an intraocular lens four months previously. At the same time, medial and lateral pterygia were excised from the right eye. His left eye was pseudophakic after an uncomplicated extracapsular cataract extraction with implantation of an intraocular lens under retrobulbar anesthesia and argon laser photocoagulation of an asymptomatic peripheral retinal break two years previously. His medical history included a myocardial infarc-
THE JOURNAL welcomes letters that describe unusual clinical or pathologic findings, experimental results, and new instruments or techniques. The title and the names of all authors appear in the Table of Contents and are retrievable through the Index Medicus and other standard indexing services. Letters must not duplicate data previously published or submitted for publication. Each letter must be accompanied by a signed disclosure statement and copyright transfer agreement published in each issue of THE JOURNAL. Letters must be typewritten, double-spaced, on 8 1/2 x H-Inch bond paper with 1 l/2-inch margins on all four sides. (See Instructions to Authors.) An original and two copies of the typescript and figures must be sent. The letters should not exceed 500 words of text. A maximum of two black-and-white figures may be used; they should be cropped or reducible to a width of 3 inches (one column). Color figures cannot be used. References should be limited to five. Letters may be referred to outside editorial referees for evaluation or may be reviewed by members of the Editorial Board. All letters are published promptly after acceptance. Authors do not receive galley proofs but if the editorial changes are extensive, the corrected typescript is submitted to them for approval. These instructions markedly limit the opportunity for an extended discussion or review. Therefore, THE JOURNAL does not publish correspondence concerning previously published letters. 209
210
AMERICAN JOURNAL OF OPHTHALMOLOGY
frontation. Results of ophthalmoscopy were normal in the right eye and showed an old peripheral retinal break surrounded by photocoagulation scars in the left eye. Medical examination, including thyroid studies and neurologic examination, demonstrated no abnormalities. Orthoptic examination showed an exotropia of 10 prism diopters with a right hypertropia of 40 prism diopters at distance and an exotropia of 16 prism diopters with a right hypertropia of 50 prism diopters at near as determined with the prism cover test in primary position while the patient was wearing his spectacles. The right hypertropia was highly incomitant and measured up to 50 prism diopters with the eyes elevated in right gaze contrasted with 25 prism diopters with the eyes depressed in left gaze. Ductions and versions showed an excess of elevation and restriction of depression of the right eye in primary position and abduction (Figure). The Bielschowsky head tilt test was unequivocal. The forced duction test showed restriction on attempts to depress the right eye. The right eye showed a floating saccade in the direction of action of the right inferior rectus muscle, which clearly indicated a palsy of this muscle. We concluded that this patient had a right inferior rectus muscle palsy with rapid onset of secondary contracture of the unopposed ipsilateral superior rectus muscle. We suspected injury of the inferior rectus muscle from the retrobulbar injection but considered also fibro-
August, 1991
sis of the superior rectus muscle from a bridlesuture injury as possible causes. Six months after the cataract extraction, the patient underwent surgical correction of his right hypertropia. During surgery the superior rectus muscle was inspected up to 12 mm posterior of its insertion and found to be normal without any scarring or other evidence of an intramuscular hemorrhage from the bridle suture. The forced duction test became negative after the superior rectus muscle had been detached from its original insertion, which indicated that this muscle had become tight after paralysis of its antagonist. Surgery consisted of a 7-mm recession of the right superior rectus muscle with a conjunctival recession, combined with a 4.5-mm resection of the right inferior rectus muscle. Three months postoperatively the patient showed a right hypertropia of only 5 prism diopters at near and distance, which increased to 10 prism diopters in right gaze. The patient was able to fuse with a slight chin elevation and had no diplopia in primary position. Transient strabismus and blepharoptosis are fairly common and benign complications of retrobulbar anesthesia. Permanent strabismus, however, is rare." Inferior rectus muscle paralysis in our patient can be explained by either direct trauma from the injection needle to the nerve of the inferior rectus muscle.v' which enters the muscle in its posterior one third, or by myotoxicity of bupivacaine hydrochloride."
Figure (de Faber and von Noorden). Versions in the nine diagnostic positions show an incomitant right hypertropia of 50 prism diopters in right gaze with the eyes elevated contrasted with only 25 prism diopters in left gaze with the eyes depressed.
Vol. 112, No.2
Letters to The Journal
References 1. von Noorden, G. K., and Hansell, R.: Clinical characteristics and treatment of isolated inferior rectus paralysis. Ophthalmology 98:253, 1991. 2. Hamed, L. H.: Strabismus presenting after cataract surgery. Ophthalmology 98:247, 1991. 3. Avilla, C. W.: Acquired strabismus in adulthood. 21st Annual Richard G. Scobee Lecture 1990. Am. Orthop. J. In press. 4. Catalano, R. A, Nelson, L. B., Calhoun, J. H., Schatz, N. J., and Harley, R. D.: Persistent strabismus presenting after cataract surgery. Ophthalmology 94:491, 1987. 5. Rainin, E. A., and Carlson, B. M.: Postoperative diplopia and ptosis. A clinical hypothesis based on the myotoxicity of local anesthetics. Arch. Ophthalmol. 103:1337, 1985.
Measurement of the Radius of Corneal Curvature With the Maloney Surgical Keratometer Hiromasa Igarashi, M.D.,
[un Akiba, M.D.,
Hiroyuki Hirokawa, M.D., and Akitoshi Yoshida, M.D.
Department of Ophthalmology, Asahikawa Medical College. Inquiries to Hiromasa Igarashi, M.D., Department of Ophthalmology, Asahikawa Medical College, 4-5, Nishikagura, Asahikawa 078, Japan. Because measuring the radius of corneal curvature in infants is sometimes difficult using an ophthalmometer and a photokeratometer, we sought an alternate method for determining the base curve when prescribing contact lenses for infants after congenital cataract surgery. The surgical keratometer developed by Maloney (Katena Products Inc., Denville, NJ) can project Placido's disk onto the cornea during surgery; the imagery then can be recorded on film or videotape.P If the image of Placido's disk can be analyzed in the same way as with the photokeratometer.v' the radius of corneal curvature can be determined without using an ophthalmometer or photokeratometer. We used a photokeratometer-based system to analyze Placido's disk projected by the surgical keratometer onto the corneas of 39 eyes of 20 healthy adults (age range, 19 to 26 years; average age, 22.3
211
years). We then evaluated the accuracy of this method. To obtain control data, the radii of corneal curvature also were measured in the same 39 eyes with an ophthalmometer. With the subjects in the supine position, 0.4% benoxinate hydrochloride drops were administered, and a Barraquer speculum was fitted. The surgical microscope was adjusted so that the cornea was centered in the visual field. The surgical keratometer that projected Placido's disk also was maintained in a fixed position over the cornea. When the disk projection was uniformly positioned over the corneal surface, the area was photographed (Figure). The projections of Placido's disk were traced on the photographs with black-and-white outliner pens, and an analysis was performed with the photokeratorneter-based corneal shape analysis unit and the PHORM 100 corneal shape analysis software system (Suncontact, Kyoto, Japan). The results then were compared with those obtained using the ophthalmometer. In 15 of the 39 subjects (38%), deviation in the value of the average radius of curvature was within 0.1 mm; in 27 subjects (69%), deviation was within 0.2 mm; and in 31 subjects (79%), deviation was within 0.3 mm. In 14 of the 39 subjects (36%), the error range of the flattest principal meridian was within 0.1 mm; in 25 subjects (64%), the range was within 0.2 mm: and in 31 subjects (79%), the range was within 0.3 mm. In cases in which the degree of corneal astigmatism was 1 diopter or more, the deviation tended to become larger. When the astigmatism was 1 diopter or less, however, the range of deviation was within 0.3 mm in 28 of 30 eyes (93%). Thus, based on these results our
Figure (Igarashi and associates). Placido's disk projected by the surgical keratometer.
