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A Marking Suture for Use in Adjustable Strabismus Surgery
614
AMERICAN JOURNAL OF OPHTHALMOLOGY
May, 1986
Figure (Abraham). Left, Vertical orientation of the polarizati?n aXi~ on the project?r (~rrow).allows the p~tient to see the screen with the right eye only. Right, Horizontal orientation of the polarization axis on the projector (arrow) allows the patient to see the screen with the left eye only.
right eye. Under these circumstances, a patient who has both eyes open is unaware that he is reading monocularly with each eye in succession, thus providing a correct visual acuity. The fraction of transmitted light (F) through two linear polarizers while one is at a 90-degree angle and the other at a variable angle (A') follows the law of Malus": F = sin/A'. Therefore, the device and the rotating polarizer create a smooth and undetectable visual stimulation transfer from one eye of the patient to the other. The slight amount of light attenuation caused by the polarizers is compensated for .by darkening the examination room, and quick rotation of the polarizer during the test masks the luminance variation. The test does not arouse the patient's suspicions and is not affected by temporary monocular closure. The device has proven to be useful in clinical practice for testing malingering, and the test confirmed its reliability when volunteers pretended to be malingering. Moreover, because it provides a test environment that approximates a normal binocular situation, the device can also be used for binocular refraction.
References 1. Gradle, H. S.: Another test for malingering. Am. J. Ophthalmol. 20:300, 1937. 2. Brackup, A. H.: A simple test for monocular malingering. Am. J. Ophthalmol. 56:659, 1963. 3. Jenkins, F. A., and White, H. E.: Fundamentals of Optics. New York, McGraw-Hill, 1957, pp. 494496.
A Marking Suture for Use in Adjustable Strabismus Surgery Gary S. Clorfeine, M.D., and William T. Parker, M.D. Department of Ophthalmology, Kaiser Permanente Medical Center.
Inquiries to Gary S. Clorieine, M. D., Department of Ophthalmology, Kaiser Permanente Medical Center, 4647 Zion Ave., San Diego, CA 92120.
In adjustable strabismus surgery, the surgeon generally measures the ocular alignment the day after the primary procedure and then either further advances or recesses the "adjustable muscle" to obtain the desired ocular alignment. The amount of additional advancement or recession is entirely empiric-the surgeon must guess how far to move the muscle to obtain the desired correction. It would be desirable to quantitate the amount of muscle movement during the adjustment process and also to monitor for any possible muscle slippage between adjustment maneuvers. We would like to suggest a technique that allows accurate measurement of both of these aspects of adjustable strabismus surgery. This technique involves the use of what we have termed a "marking suture." Surgery is performed as described by [ampolsky' using a ligature knot of 6-0 Vicryl around a muscle pu~l suture of the same material. We place an additional marking suture 5 mm from the ligature knot (Figure). This marking suture consists of 7-0 Vicryl tied in a single knot of two throws. The ends are cut very short, but not flush, so as to prevent the knot from unraveling.
Vol. 101, No.5
615
Letters to the Journal
adjustment maneuver. In this situation the adjustment may need to be done under general anesthesia. Without a marking suture it would be difficult for the surgeon to know how large an adjustment was being made without taking down the conjunctiva and directly visualizing the muscle.
Reference 1. [ampolsky, A.: Adjustable strabismus surgical procedures. In Transactions of the New Orleans Academy of Ophthalmology. St. Louis, C. V. Mosby, 1978, pp. 321-349.
Figure (Clorfeine and Parker). Quantitating the amount of muscle adjustment by measuring the distance between the marking suture (A) and the ligature knot (B).
Adjustment is performed under the operating microscope. As the adjustable muscle is either advanced or recessed, and the ligature knot moved to secure the adjustment, the distance between ligature knot and marking suture changes proportionately and this distance is easily measured with calipers. Since adjustments of 1 or 2 mm are being measured against a known 5-mm length, the measurements are accurate. When final adjustment has been completed, the surgeon can easily slide the marking suture off the end of the muscle pull suture and then tie a permanent knot. The marking suture has never been found to cause any problems. It is so small that it is not perceived as an additional foreign body. The marking suture has never unraveled or slipped and it has always been easy to slide it off when it was no longer needed. A number of important benefits are derived from the use of this technique. (1) The marking suture can be used to determine if any change in muscle position has occurred in the interval between primary surgery and the adjustment phase. (2) Use of the marking suture detects any possible slip of the muscle between adjustment maneuvers. (3) By using the marking suture in many cases, the surgeon will develop a body of information relating the amount of dioptric change in ocular alignment to each millimeter of adjustment. (4) In rare cases it is possible that a patient may not tolerate the
Visual Loss in Anterior Membrane Dystrophy Jeremy E. Levenson, M.D. Inquiries to Jeremy E. Levenson, M.D., 1260 15th St., Suite 917, Santa Monica, CA 90404.
Anterior membrane dystrophy includes a variety of dystrophic changes of the corneal epithelial basement membrane. Among these are fingerprint dystrophy, map-dot dystrophy, and Cogan's microcystic dystrophy. Although most affected patients are asymptomatic, this dystrophy plays an important role in the recurrent erosion syndrorne.?" Although mentioned less often, anterior membrane dystrophy can also cause significant visual loss, as the following cases show. An 80-year-old man scheduled to undergo a cataract operation in his right eye had a best corrected visual acuity of R. E.: 20/70 and L. E.: 20/25. Slit-lamp examination showed mild nuclear sclerotic changes in both eyes. The right cornea showed small central, white intraepithelial deposits surrounded by typical map-like dystrophic changes. The left cornea showed only mild map-like changes. On keratometry the mires of the right eye were found to be distorted. The epithelium of the right cornea was removed, and three weeks later the patient's corrected visual acuity had improved to 20/20 in the right eye. During the next two years, visual acuity in his left eye decreased to 20/60. Evaluation of the left cornea showed progression of the map-like epithelial changes, although no white cysts had appeared. The
AMERICAN JOURNAL OF OPHTHALMOLOGY
May, 1986
Figure (Abraham). Left, Vertical orientation of the polarizati?n aXi~ on the project?r (~rrow).allows the p~tient to see the screen with the right eye only. Right, Horizontal orientation of the polarization axis on the projector (arrow) allows the patient to see the screen with the left eye only.
right eye. Under these circumstances, a patient who has both eyes open is unaware that he is reading monocularly with each eye in succession, thus providing a correct visual acuity. The fraction of transmitted light (F) through two linear polarizers while one is at a 90-degree angle and the other at a variable angle (A') follows the law of Malus": F = sin/A'. Therefore, the device and the rotating polarizer create a smooth and undetectable visual stimulation transfer from one eye of the patient to the other. The slight amount of light attenuation caused by the polarizers is compensated for .by darkening the examination room, and quick rotation of the polarizer during the test masks the luminance variation. The test does not arouse the patient's suspicions and is not affected by temporary monocular closure. The device has proven to be useful in clinical practice for testing malingering, and the test confirmed its reliability when volunteers pretended to be malingering. Moreover, because it provides a test environment that approximates a normal binocular situation, the device can also be used for binocular refraction.
References 1. Gradle, H. S.: Another test for malingering. Am. J. Ophthalmol. 20:300, 1937. 2. Brackup, A. H.: A simple test for monocular malingering. Am. J. Ophthalmol. 56:659, 1963. 3. Jenkins, F. A., and White, H. E.: Fundamentals of Optics. New York, McGraw-Hill, 1957, pp. 494496.
A Marking Suture for Use in Adjustable Strabismus Surgery Gary S. Clorfeine, M.D., and William T. Parker, M.D. Department of Ophthalmology, Kaiser Permanente Medical Center.
Inquiries to Gary S. Clorieine, M. D., Department of Ophthalmology, Kaiser Permanente Medical Center, 4647 Zion Ave., San Diego, CA 92120.
In adjustable strabismus surgery, the surgeon generally measures the ocular alignment the day after the primary procedure and then either further advances or recesses the "adjustable muscle" to obtain the desired ocular alignment. The amount of additional advancement or recession is entirely empiric-the surgeon must guess how far to move the muscle to obtain the desired correction. It would be desirable to quantitate the amount of muscle movement during the adjustment process and also to monitor for any possible muscle slippage between adjustment maneuvers. We would like to suggest a technique that allows accurate measurement of both of these aspects of adjustable strabismus surgery. This technique involves the use of what we have termed a "marking suture." Surgery is performed as described by [ampolsky' using a ligature knot of 6-0 Vicryl around a muscle pu~l suture of the same material. We place an additional marking suture 5 mm from the ligature knot (Figure). This marking suture consists of 7-0 Vicryl tied in a single knot of two throws. The ends are cut very short, but not flush, so as to prevent the knot from unraveling.
Vol. 101, No.5
615
Letters to the Journal
adjustment maneuver. In this situation the adjustment may need to be done under general anesthesia. Without a marking suture it would be difficult for the surgeon to know how large an adjustment was being made without taking down the conjunctiva and directly visualizing the muscle.
Reference 1. [ampolsky, A.: Adjustable strabismus surgical procedures. In Transactions of the New Orleans Academy of Ophthalmology. St. Louis, C. V. Mosby, 1978, pp. 321-349.
Figure (Clorfeine and Parker). Quantitating the amount of muscle adjustment by measuring the distance between the marking suture (A) and the ligature knot (B).
Adjustment is performed under the operating microscope. As the adjustable muscle is either advanced or recessed, and the ligature knot moved to secure the adjustment, the distance between ligature knot and marking suture changes proportionately and this distance is easily measured with calipers. Since adjustments of 1 or 2 mm are being measured against a known 5-mm length, the measurements are accurate. When final adjustment has been completed, the surgeon can easily slide the marking suture off the end of the muscle pull suture and then tie a permanent knot. The marking suture has never been found to cause any problems. It is so small that it is not perceived as an additional foreign body. The marking suture has never unraveled or slipped and it has always been easy to slide it off when it was no longer needed. A number of important benefits are derived from the use of this technique. (1) The marking suture can be used to determine if any change in muscle position has occurred in the interval between primary surgery and the adjustment phase. (2) Use of the marking suture detects any possible slip of the muscle between adjustment maneuvers. (3) By using the marking suture in many cases, the surgeon will develop a body of information relating the amount of dioptric change in ocular alignment to each millimeter of adjustment. (4) In rare cases it is possible that a patient may not tolerate the
Visual Loss in Anterior Membrane Dystrophy Jeremy E. Levenson, M.D. Inquiries to Jeremy E. Levenson, M.D., 1260 15th St., Suite 917, Santa Monica, CA 90404.
Anterior membrane dystrophy includes a variety of dystrophic changes of the corneal epithelial basement membrane. Among these are fingerprint dystrophy, map-dot dystrophy, and Cogan's microcystic dystrophy. Although most affected patients are asymptomatic, this dystrophy plays an important role in the recurrent erosion syndrorne.?" Although mentioned less often, anterior membrane dystrophy can also cause significant visual loss, as the following cases show. An 80-year-old man scheduled to undergo a cataract operation in his right eye had a best corrected visual acuity of R. E.: 20/70 and L. E.: 20/25. Slit-lamp examination showed mild nuclear sclerotic changes in both eyes. The right cornea showed small central, white intraepithelial deposits surrounded by typical map-like dystrophic changes. The left cornea showed only mild map-like changes. On keratometry the mires of the right eye were found to be distorted. The epithelium of the right cornea was removed, and three weeks later the patient's corrected visual acuity had improved to 20/20 in the right eye. During the next two years, visual acuity in his left eye decreased to 20/60. Evaluation of the left cornea showed progression of the map-like epithelial changes, although no white cysts had appeared. The