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Hypocycloidal Tomography and Orbital Blow-Out Fracture
VOL. 68, NO. 3
483
COLLAGENASE IN THE CORNEA
Dohlman, C. H. : Collagenase in corneal ulcérations. Arch. Ophth. In press. 5. Gross, J. and Lapiere, C. M. : Collagenolytic activity in amphibian tissues: A tissue culture assay. Proc. Nat. Acad. Sci. 48:1014, 1962. 6. Lazarus, G. S., Brown, R. S., Daniels, J. R. and Fullmer, H. M. : Human granulocyte collagenase. Science 159:1483, 1968.
7. Hughes, W. F. : Alkali burns of the eye. Arch. Ophth. 35:423, 1946. 8. Dohlman, C. H., Payrau, P. and Pouliquen, Y. : L'application des lentilles de contact à l'aide de sub stances adhésives. Arch. Ophtal. 28:533, 1968. 9. Gasset, A. R. and Kaufman, H. E. : Epikeratoprosthesis : Replacement of superficial cornea by methyl methacrylate. Am. J. Ophth. 66:641, 1968.
HYPOCYCLOIDAL TOMOGRAPHY AND ORBITAL BLOW-OUT FRACTURE JACK M. DODICK, M.D.,
ARNOLD BERRETT, M.D., AND MILES A. GALIN,
M.D.
New York
The orbital floor, which roofs the maxil lary sinus for nearly its entire length, is formed by the orbital plate of the superior maxilla, the orbital surface of the zygomatic bone and the orbital process of the palate.1 Its thickness varies from 0.5 to 1.0 mm. Blow-out or hydraulic fracture of the orbit2 refers to the fracture of this normally thin floor. It has been postulated that, when a convex or spherical missile with a diameter larger than that of the orbital rim strikes the globe, the orbital contents are forced in a posterior direction and a sudden increase in intraorbi tal pressure results. This causes the area of least resistance, the thin orbital floor, to give way and fracture,2 usually posterior to the globe where the thin maxillary plate bulges forward to form a convex surface. It is not uncommon to find a fracture of the orbital rim together with the comminuted fracture of the floor. The diagnosis of orbital floor fractures is inferred by clinical signs which include enophthalmos, limitation of upward gaze, down ward displacement of the globe and anestheFrom the Departments of Ophthalmology and Radiology, New York Medical College. This study was aided by USPHS Grant NB 07162-03, by Grant 68-138 from the United Health Foundations, Inc., and by Grant T-517 from the American Can cer Society, Inc. Reprint requests to Jack M. Dodick, M.D., De partment of Ophthalmology, New York Medical College, 1249 Fifth Avenue, New York, New York 10029.
sia or hypoesthesia along the distribution of the infraorbital nerve. Incontrovertible evidence of fracture, however, depends upon X-ray visualization or surgical exploration. Unfortunately, ra diologie findings are often equivocal and contusion of extraocular muscles, levator trauma, blood in the maxillary antrum and fissure fractures may confuse or mimic clini cal findings of blow-out fracture. In an attempt to improve diagnostic tech niques, radiographie approaches to suspected blow-out fracture have included linear laminagraphy and positive-contrast orbitography. Conflicting reports2"8 concerning the value of these techniques have appeared. This project was undertaken to evaluate existing radiologie approaches to orbital blow-out fracture and to consider hypocycloidal tomography. This form of tomogra phy differs from linear laminagraphy in that the X-ray tube and film describe a hypocycloidal movement rather than a linear arc. The efficiency and clarity of this technique have been described. This method provides a sig nificant advance in the diagnosis of such fractures. MATERIALS AND METHODS
Radiologie evaluation by various tech niques was carried out in nine consecutive patients with suspected blow-out fracture. Preoperative studies included: Caldwell and Waters views of the orbits; linear lami-
484
AMERICAN JOURNAL OF OPHTHALMOLOGY
SEPTEMBER, 1969
derwent surgical exploration because of clin ical indications regardless of radiographie findings. CASE REPORTS CASE 1
Fig. 1 (Dodick, Berrett and Galin). Case 1. Hypo cycloidal tomogram 17 mm from orbital rim. Note obvious fracture site.
M. C, a 34-year-old Caucasian woman, was in volved in an automobile accident and was struck in the left orbit with the steering column of the car. She was admitted to a local hospital because of epistaxis and left periorbital ecehymosis. At this time, there was limitation of left upward gaze although the remainder of the ocular examination was nor mal. Caldwell and Waters projections and linear laminagraphy showed no evidence of floor fracture. Three weeks after discharge, hypocycloidal tomograms were done because of progressive diplopia on upward gaze. The tomograms clearly revealed a fracture of the left orbital floor (fig. 1). The pa tient was admitted to the hospital. Exploration was by an infraorbital approach. The floor was repaired with a silicone implant. CASE 2
W. B., a 69-year-old Negro man, was assaulted and beaten about the face. He was admitted for ob servation. The following day, there was consider able periorbital edema and ecehymosis on the left side. A 4-mm enophthalmos was found in the left eye, as well as limitation of upward gaze. The re mainder of the ocular examination was normal. Caldwell and Waters projections revealed a ques tionable fracture of the floor of the left orbit, frac ture of the zygomaticomalar structure and diastasis of the zygomaticofrontal suture. Because of the presence of the two fractures, it was likely that a
Fig. 2 (Dodick, Berrett and Galin). Case 2. Hypo cycloidal tomogram with clearly delineated fracture site in orbital floor.
nagraphy with single cuts at 1-cm intervals, using a 40-inch target film distance and 45degree amplitude of rotation of the X-ray tube; positive-contrast orbitography;* and hypocycloidal tomography with 10-mm co ronal and sagittal sections. All patients un* An attempt was made to keep the injection ex ternal to the muscle cone. The contrast mixture con sisted of 3.0 ml of 50% sodium diazotrate, 1.5 ml of 2% carbocaine and 0.5 ml diluent containing 300 units of hyaluronidase. Immediately after injection, the patient was repositioned in an erect posture and Caldwell and Waters views of the orbit and maxil lary sinuses were taken.
Fig. 3 (Dodick, Berrett and Galin). Case3. Waters view, indicating an opacity at suspected fracture site in orbital floor.
VOL. 68, NO. 3
HYPOCYCLOIDAL TOMOGRAPHY
floor fracture also existed. Linear tomography con firmed the two fractures but showed no definite or bital floor fracture. Positive-contrast orbitography failed to reveal contrast media in the maxillary antrum. Hypocycloidal tomography (fig. 2) clearly demonstrated a depressed fracture of the floor of the orbit. At surgical exploration, incarcerated tissue was freed from the orbital floor fracture, and the hole was repaired with a silicone implant. CASE 3
B. F., a 31-year-old Negro woman, was struck in the left orbit by a clenched fist. The following day there was marked periorbital ecchymosis and edema of the left eye, with subconjunctival hemorrhage. The remainder of the ocular examination was nor mal. Waters projections revealed an equivocal frac ture in the orbital floor (fig. 3). Positive- contrast orbitography was negative. Hypocycloidal tomogra phy clearly demonstrated the fracture (fig. 4). The patient's orbit was explored and the depressed frac ture repaired with a silicone implant. RESULTS
In eight of nine cases clinically suspected of blow-out fracture, the diagnosis was sur gically proven. No fracture was found in one case. The comparative results of the ra diologie studies undertaken are shown in Table 1. (Positive-contrast orbitography was not carried out in two cases.)
Fig. 4 (Dodick, Berrett and Galin). Case 3. Hypo cycloidal tomogram in the frontal projection clearly demonstrates a fracture in the orbital floor.
485 TABLE 1
COMPARISON OF RESULTS UTILIZING VARIOUS ROENTGEN TECHNIQUES TO DIAGNOSE ORBITAL BLOW-OUT FRACTURE
Interpretation Method of Study Caldwell and Waters views Linear laminagraphy Orbitography Hypocycloidal tomography
Missed Correctly Uncertain Diagnosis Diagnosed of Fracture 3
2
4
3 2
2 0
4 5
9
0
0
DISCUSSION
The diagnosis of blow-out fracture is often difficult. False-positive diagnoses are not uncommon, since enophthalmos, limita tion of upward gaze and other clinical signs are mimicked by trauma alone, without frac ture. Most surgeons are reluctant to explore the orbit without radiologie confirmation al though, unfortunately, the commonly em ployed radiologie techniques leave much to be desired. The orbit and surrounding bony structures are anatomically complex and, as a result, superimposed bony landmarks often obscure the orbital floor on X-ray examina tions. Moreover, in orbital trauma, overlying soft tissue swelling and antral blood further limit the value of conventional radiographs. Under such circumstances, orbital fractures may be easily overlooked. Positive-contrast orbitography has proved disappointing ; in only two of the seven cases did the contrast appear in the maxillary an trum after injection along the orbital floor. The incarcerated tissue in the dehiscence of the floor may have prevented the passage of contrast material into the antrum. Perhaps positive-contrast orbitography is only of value if performed soon after trauma before fibrous adhesions close the gap. Hypocycloidal tomography confirmed the diagnosis of blow-out fracture in eight in stances and correctly disproved the diagnosis in one case. This technique appears to be the
486
AMERICAN JOURNAL OF OPHTHALMOLOGY
most valuable of all radiologie tests in the preoperative evaluation of blow-out frac tures of the orbit. SUMMARY
Nine suspected cases of blow-out fracture of the orbit were evaluated radiologically by techniques which included Caldwell and Waters projections of the orbit, linear laminagraphy, positive-contrast orbitography and hypocycloidal tomography. All cases were then explored surgically. The accuracy of hypocycloidal tomography in evaluation of orbital floor fracture far excells all other ra diologie techniques. REFERENCES
1. Last, R. J. : Eugene Wolff's Anatomy of the
SEPTEMBER, 1969
Eye and Orbit. Philadelphia, Saunders, 1961, ed. 5, p. 6. 2. Smith, B. and Regan, W. F., Jr.: Blow-out fracture of the orbit : Mechanism and correction of internal orbital fracture. Am. J. Ophth. 44:733, 1957. 3. Morton, W. R. and Turnbull, W. : Blow-out fractures of the floor of the orbit. Canad. M. A. J. 90:58, 1964. 4. Lerman, S. and Cramer, L. M. : Blow-out frac tures of the orbit. Am. J. Ophth. 57 :264, 1964. 5. Lewin, J. R., Rhodes, D. H., Jr. and Pavsek, E. J. : Roentgenologic manifestations of fracture of orbital floor (blow-out fracture). Am. J. Roentgen. 83:628, 1960. 6. Zizmor, J., Smith, B., Fasano, C. and Con verse, J. M. : Roentgen diagnosis of blow-out frac tures of orbit. Am. J. Roentgen., 87:1009, 1962. 7. Gould, H. and Titus, C. O.: Internal orbital fractures : The value of laminagraphy in diagnosis. Am. J. Roentgen. 97:618, 1966. 8. Fueger, G. F., Milauskas, A. T. and Britton, W. : The roentgenologic evaluation of orbital blow-out injuries. Am. J. Roentgen. 97:614, 1966.
DOUBLE-STRANDED RNA, AN I N T E R F E R O N INDUCER, IN H E R P E S SIMPLEX K E R A T I T I S HERBERT E. KAUFMAN, M.D.,
EMILY D. ELLISON,
AND STEPHEN R. WALTMAN,
B.S.,
M.D.
Gainesville, Florida
Herpes virus is a weak inducer of inter feron and is relatively resistant to interferon action.1·2 In the past, attempts to treat her petic infection with interferon, or to prevent such infection by interferon, showed that it could have a slight prophylactic effect on viral keratitis. This effect was minimal and difficult to evaluate.3"5 More recently, Park and Baron8 utilized the topical and systemic administration of double-stranded RNA in the form of polyinosinic polycytidylic acid From the Department of Ophthalmology, College of Medicine, University of Florida. This project was supported by USPHS Grants NB-03S38 and NB-08210 and Special Fellowship Grant 1976-01 VSN from the National Institute of Neurological Diseases and Stroke, National Institutes of Health. Reprint requests to Herbert E. Kaufman, M.D., Department of Ophthalmology, College of Medi cine, University of Forida, Gainesville, Florida 32601.
(Poly I:C) a potent inducer of interferon. It was definitely prophylactic when given topically or intravenously, and was therapeu tic in experimental herpes simplex keratitis. The possibility that such an agent might provide an alternative and superior therapy · for this disease raised several questions: 1. How effective is Poly I :C in the treat ment of herpetic keratitis and how does it compare with the other commonly used anti viral, idoxuridine (IDU) ? 2. Does treatment of the acute disease with topical or systemic Poly I:C, even if less effective than IDU, reduce the recur rence rate of herpetic keratitis? 3. Does treatment of the acute disease with systemic Poly I :C prevent systemic spread of the virus from ocular infection ? 4. How long can the protection afforded by Poly I :C be maintained ?
483
COLLAGENASE IN THE CORNEA
Dohlman, C. H. : Collagenase in corneal ulcérations. Arch. Ophth. In press. 5. Gross, J. and Lapiere, C. M. : Collagenolytic activity in amphibian tissues: A tissue culture assay. Proc. Nat. Acad. Sci. 48:1014, 1962. 6. Lazarus, G. S., Brown, R. S., Daniels, J. R. and Fullmer, H. M. : Human granulocyte collagenase. Science 159:1483, 1968.
7. Hughes, W. F. : Alkali burns of the eye. Arch. Ophth. 35:423, 1946. 8. Dohlman, C. H., Payrau, P. and Pouliquen, Y. : L'application des lentilles de contact à l'aide de sub stances adhésives. Arch. Ophtal. 28:533, 1968. 9. Gasset, A. R. and Kaufman, H. E. : Epikeratoprosthesis : Replacement of superficial cornea by methyl methacrylate. Am. J. Ophth. 66:641, 1968.
HYPOCYCLOIDAL TOMOGRAPHY AND ORBITAL BLOW-OUT FRACTURE JACK M. DODICK, M.D.,
ARNOLD BERRETT, M.D., AND MILES A. GALIN,
M.D.
New York
The orbital floor, which roofs the maxil lary sinus for nearly its entire length, is formed by the orbital plate of the superior maxilla, the orbital surface of the zygomatic bone and the orbital process of the palate.1 Its thickness varies from 0.5 to 1.0 mm. Blow-out or hydraulic fracture of the orbit2 refers to the fracture of this normally thin floor. It has been postulated that, when a convex or spherical missile with a diameter larger than that of the orbital rim strikes the globe, the orbital contents are forced in a posterior direction and a sudden increase in intraorbi tal pressure results. This causes the area of least resistance, the thin orbital floor, to give way and fracture,2 usually posterior to the globe where the thin maxillary plate bulges forward to form a convex surface. It is not uncommon to find a fracture of the orbital rim together with the comminuted fracture of the floor. The diagnosis of orbital floor fractures is inferred by clinical signs which include enophthalmos, limitation of upward gaze, down ward displacement of the globe and anestheFrom the Departments of Ophthalmology and Radiology, New York Medical College. This study was aided by USPHS Grant NB 07162-03, by Grant 68-138 from the United Health Foundations, Inc., and by Grant T-517 from the American Can cer Society, Inc. Reprint requests to Jack M. Dodick, M.D., De partment of Ophthalmology, New York Medical College, 1249 Fifth Avenue, New York, New York 10029.
sia or hypoesthesia along the distribution of the infraorbital nerve. Incontrovertible evidence of fracture, however, depends upon X-ray visualization or surgical exploration. Unfortunately, ra diologie findings are often equivocal and contusion of extraocular muscles, levator trauma, blood in the maxillary antrum and fissure fractures may confuse or mimic clini cal findings of blow-out fracture. In an attempt to improve diagnostic tech niques, radiographie approaches to suspected blow-out fracture have included linear laminagraphy and positive-contrast orbitography. Conflicting reports2"8 concerning the value of these techniques have appeared. This project was undertaken to evaluate existing radiologie approaches to orbital blow-out fracture and to consider hypocycloidal tomography. This form of tomogra phy differs from linear laminagraphy in that the X-ray tube and film describe a hypocycloidal movement rather than a linear arc. The efficiency and clarity of this technique have been described. This method provides a sig nificant advance in the diagnosis of such fractures. MATERIALS AND METHODS
Radiologie evaluation by various tech niques was carried out in nine consecutive patients with suspected blow-out fracture. Preoperative studies included: Caldwell and Waters views of the orbits; linear lami-
484
AMERICAN JOURNAL OF OPHTHALMOLOGY
SEPTEMBER, 1969
derwent surgical exploration because of clin ical indications regardless of radiographie findings. CASE REPORTS CASE 1
Fig. 1 (Dodick, Berrett and Galin). Case 1. Hypo cycloidal tomogram 17 mm from orbital rim. Note obvious fracture site.
M. C, a 34-year-old Caucasian woman, was in volved in an automobile accident and was struck in the left orbit with the steering column of the car. She was admitted to a local hospital because of epistaxis and left periorbital ecehymosis. At this time, there was limitation of left upward gaze although the remainder of the ocular examination was nor mal. Caldwell and Waters projections and linear laminagraphy showed no evidence of floor fracture. Three weeks after discharge, hypocycloidal tomograms were done because of progressive diplopia on upward gaze. The tomograms clearly revealed a fracture of the left orbital floor (fig. 1). The pa tient was admitted to the hospital. Exploration was by an infraorbital approach. The floor was repaired with a silicone implant. CASE 2
W. B., a 69-year-old Negro man, was assaulted and beaten about the face. He was admitted for ob servation. The following day, there was consider able periorbital edema and ecehymosis on the left side. A 4-mm enophthalmos was found in the left eye, as well as limitation of upward gaze. The re mainder of the ocular examination was normal. Caldwell and Waters projections revealed a ques tionable fracture of the floor of the left orbit, frac ture of the zygomaticomalar structure and diastasis of the zygomaticofrontal suture. Because of the presence of the two fractures, it was likely that a
Fig. 2 (Dodick, Berrett and Galin). Case 2. Hypo cycloidal tomogram with clearly delineated fracture site in orbital floor.
nagraphy with single cuts at 1-cm intervals, using a 40-inch target film distance and 45degree amplitude of rotation of the X-ray tube; positive-contrast orbitography;* and hypocycloidal tomography with 10-mm co ronal and sagittal sections. All patients un* An attempt was made to keep the injection ex ternal to the muscle cone. The contrast mixture con sisted of 3.0 ml of 50% sodium diazotrate, 1.5 ml of 2% carbocaine and 0.5 ml diluent containing 300 units of hyaluronidase. Immediately after injection, the patient was repositioned in an erect posture and Caldwell and Waters views of the orbit and maxil lary sinuses were taken.
Fig. 3 (Dodick, Berrett and Galin). Case3. Waters view, indicating an opacity at suspected fracture site in orbital floor.
VOL. 68, NO. 3
HYPOCYCLOIDAL TOMOGRAPHY
floor fracture also existed. Linear tomography con firmed the two fractures but showed no definite or bital floor fracture. Positive-contrast orbitography failed to reveal contrast media in the maxillary antrum. Hypocycloidal tomography (fig. 2) clearly demonstrated a depressed fracture of the floor of the orbit. At surgical exploration, incarcerated tissue was freed from the orbital floor fracture, and the hole was repaired with a silicone implant. CASE 3
B. F., a 31-year-old Negro woman, was struck in the left orbit by a clenched fist. The following day there was marked periorbital ecchymosis and edema of the left eye, with subconjunctival hemorrhage. The remainder of the ocular examination was nor mal. Waters projections revealed an equivocal frac ture in the orbital floor (fig. 3). Positive- contrast orbitography was negative. Hypocycloidal tomogra phy clearly demonstrated the fracture (fig. 4). The patient's orbit was explored and the depressed frac ture repaired with a silicone implant. RESULTS
In eight of nine cases clinically suspected of blow-out fracture, the diagnosis was sur gically proven. No fracture was found in one case. The comparative results of the ra diologie studies undertaken are shown in Table 1. (Positive-contrast orbitography was not carried out in two cases.)
Fig. 4 (Dodick, Berrett and Galin). Case 3. Hypo cycloidal tomogram in the frontal projection clearly demonstrates a fracture in the orbital floor.
485 TABLE 1
COMPARISON OF RESULTS UTILIZING VARIOUS ROENTGEN TECHNIQUES TO DIAGNOSE ORBITAL BLOW-OUT FRACTURE
Interpretation Method of Study Caldwell and Waters views Linear laminagraphy Orbitography Hypocycloidal tomography
Missed Correctly Uncertain Diagnosis Diagnosed of Fracture 3
2
4
3 2
2 0
4 5
9
0
0
DISCUSSION
The diagnosis of blow-out fracture is often difficult. False-positive diagnoses are not uncommon, since enophthalmos, limita tion of upward gaze and other clinical signs are mimicked by trauma alone, without frac ture. Most surgeons are reluctant to explore the orbit without radiologie confirmation al though, unfortunately, the commonly em ployed radiologie techniques leave much to be desired. The orbit and surrounding bony structures are anatomically complex and, as a result, superimposed bony landmarks often obscure the orbital floor on X-ray examina tions. Moreover, in orbital trauma, overlying soft tissue swelling and antral blood further limit the value of conventional radiographs. Under such circumstances, orbital fractures may be easily overlooked. Positive-contrast orbitography has proved disappointing ; in only two of the seven cases did the contrast appear in the maxillary an trum after injection along the orbital floor. The incarcerated tissue in the dehiscence of the floor may have prevented the passage of contrast material into the antrum. Perhaps positive-contrast orbitography is only of value if performed soon after trauma before fibrous adhesions close the gap. Hypocycloidal tomography confirmed the diagnosis of blow-out fracture in eight in stances and correctly disproved the diagnosis in one case. This technique appears to be the
486
AMERICAN JOURNAL OF OPHTHALMOLOGY
most valuable of all radiologie tests in the preoperative evaluation of blow-out frac tures of the orbit. SUMMARY
Nine suspected cases of blow-out fracture of the orbit were evaluated radiologically by techniques which included Caldwell and Waters projections of the orbit, linear laminagraphy, positive-contrast orbitography and hypocycloidal tomography. All cases were then explored surgically. The accuracy of hypocycloidal tomography in evaluation of orbital floor fracture far excells all other ra diologie techniques. REFERENCES
1. Last, R. J. : Eugene Wolff's Anatomy of the
SEPTEMBER, 1969
Eye and Orbit. Philadelphia, Saunders, 1961, ed. 5, p. 6. 2. Smith, B. and Regan, W. F., Jr.: Blow-out fracture of the orbit : Mechanism and correction of internal orbital fracture. Am. J. Ophth. 44:733, 1957. 3. Morton, W. R. and Turnbull, W. : Blow-out fractures of the floor of the orbit. Canad. M. A. J. 90:58, 1964. 4. Lerman, S. and Cramer, L. M. : Blow-out frac tures of the orbit. Am. J. Ophth. 57 :264, 1964. 5. Lewin, J. R., Rhodes, D. H., Jr. and Pavsek, E. J. : Roentgenologic manifestations of fracture of orbital floor (blow-out fracture). Am. J. Roentgen. 83:628, 1960. 6. Zizmor, J., Smith, B., Fasano, C. and Con verse, J. M. : Roentgen diagnosis of blow-out frac tures of orbit. Am. J. Roentgen., 87:1009, 1962. 7. Gould, H. and Titus, C. O.: Internal orbital fractures : The value of laminagraphy in diagnosis. Am. J. Roentgen. 97:618, 1966. 8. Fueger, G. F., Milauskas, A. T. and Britton, W. : The roentgenologic evaluation of orbital blow-out injuries. Am. J. Roentgen. 97:614, 1966.
DOUBLE-STRANDED RNA, AN I N T E R F E R O N INDUCER, IN H E R P E S SIMPLEX K E R A T I T I S HERBERT E. KAUFMAN, M.D.,
EMILY D. ELLISON,
AND STEPHEN R. WALTMAN,
B.S.,
M.D.
Gainesville, Florida
Herpes virus is a weak inducer of inter feron and is relatively resistant to interferon action.1·2 In the past, attempts to treat her petic infection with interferon, or to prevent such infection by interferon, showed that it could have a slight prophylactic effect on viral keratitis. This effect was minimal and difficult to evaluate.3"5 More recently, Park and Baron8 utilized the topical and systemic administration of double-stranded RNA in the form of polyinosinic polycytidylic acid From the Department of Ophthalmology, College of Medicine, University of Florida. This project was supported by USPHS Grants NB-03S38 and NB-08210 and Special Fellowship Grant 1976-01 VSN from the National Institute of Neurological Diseases and Stroke, National Institutes of Health. Reprint requests to Herbert E. Kaufman, M.D., Department of Ophthalmology, College of Medi cine, University of Forida, Gainesville, Florida 32601.
(Poly I:C) a potent inducer of interferon. It was definitely prophylactic when given topically or intravenously, and was therapeu tic in experimental herpes simplex keratitis. The possibility that such an agent might provide an alternative and superior therapy · for this disease raised several questions: 1. How effective is Poly I :C in the treat ment of herpetic keratitis and how does it compare with the other commonly used anti viral, idoxuridine (IDU) ? 2. Does treatment of the acute disease with topical or systemic Poly I:C, even if less effective than IDU, reduce the recur rence rate of herpetic keratitis? 3. Does treatment of the acute disease with systemic Poly I :C prevent systemic spread of the virus from ocular infection ? 4. How long can the protection afforded by Poly I :C be maintained ?