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Soft Vacuum Lens for Foreign Body Localization
S O F T VACUUM LENS FOR FOREIGN BODY LOCALIZATION HEENANDO CARDONA, M.D.,
AIm STEPHEN L. TROKEL,
M.D.
New York, New York There are two widely used geometric methods of localizing intraocular foreign bodies. The chief virtue of the Sweets method, virtually unchanged since its intro duction early this century, is that the localiz ing markers are 10 mm in the front of the corneal apex which obviates touching the globe. For this reason, this method has al ways been the choice of radiologists. How ever, errors are introduced because the geo metric reference is in front of the globe, and the localizing reference alters if the eye moves. The Sweets method localizes in the frontal and lateral plane which makes it in accurate in determining whether a foreign body is within the scierai coats and truly intraocular. Because of these problems, most ophthal mologists prefer geometric markers placed on the globe. These markers permit localiza tion in the frontal plane and the meridional plane. An ingenious variety of markers have been described since split bird shot was su tured to the globe in 1905 and glass shells with the limbus marked were placed on the globe in 1910. The use of a contact glass with a marker for the limbus has remained popular. One drawback is that the lens, and hence the reference markers, change position under the stresses produced by gravity and ocular movement. Attempts to stop lens movements include shaping the lens to fit the conjunctival fornices and the use of a vac uum tube to hold the lens in position. How ever, because of the variation of shapes of globes, no method has been entirely satisfac tory. From the Department of Ophthalmology, Ed ward S. Harkness Eye Institute, College of Physi cians and Surgeons, Columbia University, New York. Reprint Requests to Stephen L. Trokel, M.D., Edward S. Harkness Eye Institute, 635 West 165th Street, New York, New York 10032.
This report describes a soft contact lens* which overcomes this objection and allows rigid positioning of a geometric marker on the limbal groove of eyes of a wide variety of shapes. Because it is of soft material, it will not injure the eye. It may be sterilized, it can be positioned and removed quickly, and it is readily tolerated by the patient. MATERIAL
The lens and its attached suction cup han dle are made of silicone rubber (Fig. 1). The contact lens section has a diameter of 17.0 mm and resembles a corneoscleral lens. It has 6.5 mm radius in the corneal section and 10 mm radius in the scierai section. We use these steep radii because they can adapt easily to all corneal and scierai curvatures. This stabilizes the position of the corneal portion of the lens. The scierai flange of the lens is slightly thinner and produces a dia phragm action which allows adaptability to a wide range of ocular sizes. The handle gen erates a vacuum which shapes the corneal and scierai sections to the globe. The junction between the corneal section and the scierai section has a molded groove which holds either four quadrants of a ring of flexible stainless wire 11 mm in diameter or a capillary tube filled with x-ray opaque material. METHOD
The lens is moistened with contact lens wetting solution and the upper flange of the lens is placed under the upper eyelid. The lower eyelid is then pulled down and the lens is centered on the cornea. Slight compression of the bulb is necessary to achieve adequate suction and adhesion of the localizer. The position of the lens may be shifted by slightly squeezing the bulb to release the vac uum on the cornea. This allows precise posi* Manufactured by Edward S. Week.
VOL. 74, NO. 2
FOREIGN BODY LOCALIZATION
Fig. 1 (Cardona and Trokel). Soft silicone for eign body localizer. The contact lens section on the left has either a radiopaque ring or four quadrants of the ring (arrow) to locate the limbus. Suction is controlled by pressure on the handle.
tioning of the markers with relation to the limbus. A secure relationship between the lens and the globe is then achieved (Fig. 2 ) . When adjusted, the lens will not shift its position with respect to the globe. Gravity and the stress of ocular movement do not dislodge it.
297
which allows the advantage of simulta neous posterior-anterior orbital and lateral views. A second, or portable x-ray unit is used at right angles to the table or head unit and two orthogonal views are simultaneously prepared. We have found it entirely satisfactory to take two separate x-rays after reposition ing the patient. The lateral view is taken with the affected eye against the radiographic casette. Care is taken to position the skull so a true lateral is obtained. The eye is moved so the suction plunger of lens is par allel to the casette, and a coned x-ray is taken. The patient is then moved to face the x-ray casette and placed with the forehead extended. He moves his eyes to adjust their position so the suction bulb is perpendicular to the casette. The radiographie tube is set at zero (perpendicular to the casette and parallel to the visual axis) and a coned x-ray is taken. As with other contact localization methods,2·3 the foreign body is localized in the anterior view and then in the meridional section. Meridional section localization is not a lateral view which may falsely locate a for eign body as intraocular when it is truly extraocular. Each x-ray film is produced with a specific amount of magnification, roughly 10%. The amount of magnification may be calculated using the localizer ring as a refer ence size.
RADIOGRAPHY
Localization of the foreign body requires radiographs made in two planes—a lateral and posterior-anterior view of the orbit. These two views are necessary in all tech niques using corneoscleral markers. With modern x-ray equipment, tables and special head holders to position the skull are not necessary. A radiographie head unit is ideal for preparation of the required radiographs. Recently, a right angle holder was described1
Fig. 2 (Cardona and Trokel). Foreign body lo calizer in position on left eye. The position of the ring may be seen in apposition to the corneoscleral limbus through the translucent plastic.
298
T H E AMERICAN JOURNAL OF OPHTHALMOLOGY
The distance and angle from the center of the globe is determined in the posterior-ante rior radiograph and, after correction for magnification, transferred to the anterior lo calization chart. The distance behind the limbal plane is de termined in the lateral x-ray, and corrected for magnification. This distance, with the distance from the axis of the globe, is trans ferred to the meridional diagram and locates the foreign body. If the foreign body is large, the extremes may be localized and the extent of the foreign body diagrammed in the localization chart. CLINICAL RESULTS
The localizer has been used in 14 patients, two of whom had recently sutured small corneal lacerations with maintenance of the an terior chamber. In all cases, localization was successfully performed. Examination of the cornea after localization indicated an intact epithelium with no evidence of staining with fluorescein. COMMENTS
Experience has shown that the critical ad vantage of this lens is the rapid yet precise
AUGUST, 1972
placement of the corneoscleral radiopaque markers. This makes it simple to obtain right-angle x-rays that accurately locate the foreign body with respect to the corneo scleral markers. The flexibility of the lens material has increased patient tolerance and cooperation. We have found our localiza tions are more accurate with the use of this device, and the necessity for repeat examina tion because of localization lens slippage has been eliminated. SUMMARY
A soft silicone foreign body localizer has been developed which will not shift position on the globe. The fixed geometric reference points allow accurate localization without the necessity for repeat examination because of lens slippage. No corneal staining has been found after its use. REFERENCES
1. Bronson, N. R., and Poisson, R. J. : A new ro entgen ray localization technique. Tr. Am. Acad. Ophth. Otolaryng. 74:828, 1970. 2. Comberg, W. : Ein neues Verfahren zur Rontgenlokalisation am Augapfel, von Graefe's Arch. Ophth. 118:175, 1927. 3. Pfeiffer, R. L. : Localization of intraocular foreign bodies with the contact lens. Am. J. Roent. Rad. Ther. 44:558, 1940.
AIm STEPHEN L. TROKEL,
M.D.
New York, New York There are two widely used geometric methods of localizing intraocular foreign bodies. The chief virtue of the Sweets method, virtually unchanged since its intro duction early this century, is that the localiz ing markers are 10 mm in the front of the corneal apex which obviates touching the globe. For this reason, this method has al ways been the choice of radiologists. How ever, errors are introduced because the geo metric reference is in front of the globe, and the localizing reference alters if the eye moves. The Sweets method localizes in the frontal and lateral plane which makes it in accurate in determining whether a foreign body is within the scierai coats and truly intraocular. Because of these problems, most ophthal mologists prefer geometric markers placed on the globe. These markers permit localiza tion in the frontal plane and the meridional plane. An ingenious variety of markers have been described since split bird shot was su tured to the globe in 1905 and glass shells with the limbus marked were placed on the globe in 1910. The use of a contact glass with a marker for the limbus has remained popular. One drawback is that the lens, and hence the reference markers, change position under the stresses produced by gravity and ocular movement. Attempts to stop lens movements include shaping the lens to fit the conjunctival fornices and the use of a vac uum tube to hold the lens in position. How ever, because of the variation of shapes of globes, no method has been entirely satisfac tory. From the Department of Ophthalmology, Ed ward S. Harkness Eye Institute, College of Physi cians and Surgeons, Columbia University, New York. Reprint Requests to Stephen L. Trokel, M.D., Edward S. Harkness Eye Institute, 635 West 165th Street, New York, New York 10032.
This report describes a soft contact lens* which overcomes this objection and allows rigid positioning of a geometric marker on the limbal groove of eyes of a wide variety of shapes. Because it is of soft material, it will not injure the eye. It may be sterilized, it can be positioned and removed quickly, and it is readily tolerated by the patient. MATERIAL
The lens and its attached suction cup han dle are made of silicone rubber (Fig. 1). The contact lens section has a diameter of 17.0 mm and resembles a corneoscleral lens. It has 6.5 mm radius in the corneal section and 10 mm radius in the scierai section. We use these steep radii because they can adapt easily to all corneal and scierai curvatures. This stabilizes the position of the corneal portion of the lens. The scierai flange of the lens is slightly thinner and produces a dia phragm action which allows adaptability to a wide range of ocular sizes. The handle gen erates a vacuum which shapes the corneal and scierai sections to the globe. The junction between the corneal section and the scierai section has a molded groove which holds either four quadrants of a ring of flexible stainless wire 11 mm in diameter or a capillary tube filled with x-ray opaque material. METHOD
The lens is moistened with contact lens wetting solution and the upper flange of the lens is placed under the upper eyelid. The lower eyelid is then pulled down and the lens is centered on the cornea. Slight compression of the bulb is necessary to achieve adequate suction and adhesion of the localizer. The position of the lens may be shifted by slightly squeezing the bulb to release the vac uum on the cornea. This allows precise posi* Manufactured by Edward S. Week.
VOL. 74, NO. 2
FOREIGN BODY LOCALIZATION
Fig. 1 (Cardona and Trokel). Soft silicone for eign body localizer. The contact lens section on the left has either a radiopaque ring or four quadrants of the ring (arrow) to locate the limbus. Suction is controlled by pressure on the handle.
tioning of the markers with relation to the limbus. A secure relationship between the lens and the globe is then achieved (Fig. 2 ) . When adjusted, the lens will not shift its position with respect to the globe. Gravity and the stress of ocular movement do not dislodge it.
297
which allows the advantage of simulta neous posterior-anterior orbital and lateral views. A second, or portable x-ray unit is used at right angles to the table or head unit and two orthogonal views are simultaneously prepared. We have found it entirely satisfactory to take two separate x-rays after reposition ing the patient. The lateral view is taken with the affected eye against the radiographic casette. Care is taken to position the skull so a true lateral is obtained. The eye is moved so the suction plunger of lens is par allel to the casette, and a coned x-ray is taken. The patient is then moved to face the x-ray casette and placed with the forehead extended. He moves his eyes to adjust their position so the suction bulb is perpendicular to the casette. The radiographie tube is set at zero (perpendicular to the casette and parallel to the visual axis) and a coned x-ray is taken. As with other contact localization methods,2·3 the foreign body is localized in the anterior view and then in the meridional section. Meridional section localization is not a lateral view which may falsely locate a for eign body as intraocular when it is truly extraocular. Each x-ray film is produced with a specific amount of magnification, roughly 10%. The amount of magnification may be calculated using the localizer ring as a refer ence size.
RADIOGRAPHY
Localization of the foreign body requires radiographs made in two planes—a lateral and posterior-anterior view of the orbit. These two views are necessary in all tech niques using corneoscleral markers. With modern x-ray equipment, tables and special head holders to position the skull are not necessary. A radiographie head unit is ideal for preparation of the required radiographs. Recently, a right angle holder was described1
Fig. 2 (Cardona and Trokel). Foreign body lo calizer in position on left eye. The position of the ring may be seen in apposition to the corneoscleral limbus through the translucent plastic.
298
T H E AMERICAN JOURNAL OF OPHTHALMOLOGY
The distance and angle from the center of the globe is determined in the posterior-ante rior radiograph and, after correction for magnification, transferred to the anterior lo calization chart. The distance behind the limbal plane is de termined in the lateral x-ray, and corrected for magnification. This distance, with the distance from the axis of the globe, is trans ferred to the meridional diagram and locates the foreign body. If the foreign body is large, the extremes may be localized and the extent of the foreign body diagrammed in the localization chart. CLINICAL RESULTS
The localizer has been used in 14 patients, two of whom had recently sutured small corneal lacerations with maintenance of the an terior chamber. In all cases, localization was successfully performed. Examination of the cornea after localization indicated an intact epithelium with no evidence of staining with fluorescein. COMMENTS
Experience has shown that the critical ad vantage of this lens is the rapid yet precise
AUGUST, 1972
placement of the corneoscleral radiopaque markers. This makes it simple to obtain right-angle x-rays that accurately locate the foreign body with respect to the corneo scleral markers. The flexibility of the lens material has increased patient tolerance and cooperation. We have found our localiza tions are more accurate with the use of this device, and the necessity for repeat examina tion because of localization lens slippage has been eliminated. SUMMARY
A soft silicone foreign body localizer has been developed which will not shift position on the globe. The fixed geometric reference points allow accurate localization without the necessity for repeat examination because of lens slippage. No corneal staining has been found after its use. REFERENCES
1. Bronson, N. R., and Poisson, R. J. : A new ro entgen ray localization technique. Tr. Am. Acad. Ophth. Otolaryng. 74:828, 1970. 2. Comberg, W. : Ein neues Verfahren zur Rontgenlokalisation am Augapfel, von Graefe's Arch. Ophth. 118:175, 1927. 3. Pfeiffer, R. L. : Localization of intraocular foreign bodies with the contact lens. Am. J. Roent. Rad. Ther. 44:558, 1940.