- Email: [email protected]
Myiasis Palpebrarum
496
TABLE
References
SULFONAMIDE·INDUCED CHANGES CHANGES
R.E.
LE.
Total induced myopia (diopters)
4.00 0.27
3.00 0.28
Lens thickening (mm) Myopia caused by lens thickening
3.46 87 0.25
Diopters
% of total Anterior lens displacement (mm) Myopia caused by anterior lens displacement Diopters
0.54
13
% of total
2.57
86 0.21 0.43 14
In this condition cycloplegia does not change the induced myopia. Finally, in transient myopia caused by accommodative spasm, the entire myopic change is eliminated with cycloplegia and no anterior movement of the entire lens is present. A combination of cycloplegic refraction and ultrasonographic A-scan measurement of lens position allows the underlying mechanism in transient myopia to be determined and aids in the differential diagnosis. For easy reference a flow diagram is shown in the Figure.
1. Fraunfelder, F. T.: Drug-induced Ocular Side Effects and Drug Interactions, 2nd ed. Philadelphia, Lea and Febiger, 1982, pp. 40-43, 359-361, 461, and 462. 2. Bovino, J. A., and Marcus, D. F.: The mechanism of transient myopia induced by sulfonamide therapy. Am. J. Ophthalmol. 94:99, 1982. 3. Chirls, I. A., and Norris, J. W.: Transient myopia associated with vaginal sulfonilamide suppositories. Am. J. Ophthalmol. 98:120, 1984. 4. [arnpolsky, A., and Flan, B.: Transient myopia associated with anterior misplacement of the crystalline lens. Am. J. Ophthalmol. 36:81, 1953. 5. Kimura, R., Kasi, M., Shoji, K., and Kanno, c.. Swollen ciliary processes as an initial symptom in Vogt-Koyanagi-Harada syndrome. Am. J. Ophthalmol. 95:402, 1983.
Myiasis Palpebrarum Kirk R. Wilhelmus, M.D. Ocular Microbiology Laboratory, Cullen Eye Institute, Baylor College of Medicine. This study was supported in part by grants from the Sid W. Richardson Foundation and Research to Prevent Blindness, Inc. Inquiries to Kirk R. Wilhelmus, M.D., 6501 Fannin St., Houston, TX 77030.
Transient Myopia
-
Yes Reversal with Cycloplegia
Normal Accommodation Ciliary Spasm Accomodative Spasm
No Anterior Movement of Posterior Lens Vertex No
April, 1986
AMERICAN JOURNAL OF OPHTHALMOLOGY
-
Yes
Ciliary Body Edema: Sulfas Vogt-Koyanagi-Harada's Isoniazid
It
Lenticular Edema: Diabetes Mellitus Uremia
Figure (Hook and associates). Flow diagram for differentiating causes of transient myopia.
The most common cause of cutaneous maggot infestation in humans is the botfly, Dermatobia hominis, found in the tropical regions of Central and South America. Ophthalmomyiasis is infrequent, representing less than 5% of all sites, although eyelid involvement is possible!" and can be misdiagnosed as bacterial preseptal cellulitis. I examined a woman in Cali, Colombia, who had palpebral myiasis. She recalled an insect bite on the right upper eyelid a few weeks previously. Swelling and pruritus gradually developed. As the discomfort increased, she began having intermittent crawling and wriggling sensations under the skin. In addition to eyelid cellulitis and lymphangiitis (Fig. 1), there was an aperture with a small amount of hemoserous discharge. After gentle probing, this produced a retractile structure. Petrolatum ophthalmic ointment was applied to the punctal lesion, and shortly afterwards the posterior end of a maggot appeared and
Vol. 101, No. 4
Letters to The Journal
Fig. 1 (Wilhelmus). Eyelid cellulitis with a small pore through which the caudal end of a maggot intermittently appeared. was grasped with toothed forceps. Because the opening apparently needed enlarging, 2% lidocaine was locally injected whereupon the parasite stopped moving and was gently extracted (Fig. 2). The bristling, backward-directed black spicules on the third-instar larva's anterior segment made removal somewhat difficult. After local irrigation of the subcutaneous cavity, the patient healed satisfactorily within the next week. How human parasitism by D. hominis comes about is peculiar. 5 Living mainly in the transequatorial, coffee-growing, wooded highlands of tropical America (18 S to 25 N) adult botflies, which resemble bumble bees, are rarely seen,
Fig. 2 (Wilhelmus). Late-stage Dermatobia hominis larva, 15 mm in length, removed from eyelid lesion. Note black spines on anterior segments.
497
living only to mate and never feeding. Copulation is initiated by aggressive male pouncing behavior related to visual stimuli toward the female. Subsequently, the female oviposits her eggs during daylight onto a captured, flying, hematophagus insect like a Psorophora mosquito, gluing them onto the lateral or ventral side with a water-insoluble, quick-drying cement that avoids interference with the vector's flight efficiency. Attached by their posterior ends, the eggs are transported by the carrier insect. When in contact with a warm-blooded host, usually cattle but sometimes humans or various domestic and wild animals, the eggs hatch when stimulated by a sudden temperature increase when the porter insect alights. A l-rnrn first-stage larva emerges through the egg's anterior operculum pointed toward the skin where it can enter via the vector's puncture wound or painlessly chew through intact skin within several minutes. After burrowing into the subcutaneous tissue, the larva, or bot, molts twice through three stages called instars over the next four to 18 weeks. A local furuncular lesion, or warble, forms after two to three weeks with a skin opening acting as a respiratory pore so that the maggot's caudal pair of spiracles can provide an adequate air supply. Staying close to the wound's surface, el t6rsalo (from the Spanish torcer, to twist) intermittently moves within the skin cavity, especially at night. A few may die and produce a chalazionlike lesion, but in the proper host the larva eventually backs out with peristaltic contractions through the breathing orifice during the early morning to drop to the ground where it actively buries itself in the surface soil for a four- to l l-week pupation. The adult flies mate within one day and live for only about one week. Fossils resembling D. hominis have been traced to the Paleocene period, 60 million years ago, and these flies have been studied for three centuries. No one has yet acquired D. hominis infestation within the United States, but imported cases have been reported since work began on the Panama Canal. Most have occurred on the arms and legs; cutaneous myiasis of the head appears to be relatively uncommon. Because these cuterebrid eggs are usually transported by mosquito carriers, an insect repellant should offer protection in the indigenous zones. The treatment of ophthalmomyiasis externa is relatively straightforward once the correct diagnosis is made.
498
AMERICAN JOURNAL OF OPHTHALMOLOGY
References 1. Negro, R. c., Ferrer, J., Osimani, J. J., and Galli, M. A.: Oftalmomiasis por Dermatobia hominis. Arch. Pediatr. Uruguay 40:60, 1969. 2. Lopez, M., and Arrivillaga, R.: Miasis ocular. Rev. Oftalmol. Venez. 27:185, 1971. 3. Cordero-Moreno, R.: Etiologic factors in tropical eye diseases. Second American Journal of Ophthalmology and Pan American Association of Ophthalmology Lecture. Am. J. Ophthalmol. 75:349, 1973. 4. Ruggiero, G., Galiano, P., DiDeco, M., and Biava, G. L.: Secao de doencas externas oculares da faculdade de medicina de jundiae. Rev. Bras. Oftalmol. 40:325, 1981. 5. Carts, E. P.: Biology of New World bot flies. Cuterebridae. Ann. Rev. Entomol. 27:313, 1982.
A Simplified Method for Viewing Slides Stereoscopically
April, 1986
The head is held still and the left lens is aligned on the right paired photograph in the same way. When both eyes are open, the two photographs can be viewed stereoscopically. Once properly adjusted, the loupes do not need to be altered. Nonstereoscopic slides can be examined with the same loupes or at a higher magnification with x4 loupes at a 14-cm working distance. This gives approximately the same magnification as a standard 25-diopter hand viewer. I believe this method will be of general interest and I am not aware of it being described previously. I helieve it greatly facilitates the reading of slides. It offers improved comfort, a better working distance, a greater depth of focus, and the ability to find a particular photograph or to scan photographs more rapidly as well as clear peripheral vision, which is useful when making notes and finding slides. It works well for single slides, slides mounted in plastic holding sheets, or strips of film. I trust others will be spared hours of discomfort and fatigue by using this easy method.
Hugh R. Taylor, M.D.
International Center for Preventive and Epidemiologic Ophthalmology, Wilmer Institute, Johns Hopkins University. Inquiries to Hugh R. Taylor, M.D., Wilmer Institute, Johns Hopkins Hospital, Baltimore, MD 21205.
Sometimes it is necessary to examine large numbers of slides, such as fundus photographs, fluorescein angiographs, or photographs for cataract or trachoma grading. The standard method for either carefully grading or merely scanning these slides is to place them on a light box and to use a small hand magnifier or stereoscopic viewer. This is tiresome, tedious work and requires long hours of working over a light box with your face only inches from the work surface. Alternatively, + 10-diopter aphakic spectacles can be used but they again dictate a short working distance and distant peripheral vision. Recently, I tried an alternate method of reading slides using a standard spectacle magnifying loupe. Stereoscopic paired slides can be easily viewed stereoscopically by correctly adjusting the loupes as the x2.5 Oculist loupe on which the individual telescopes are individually adjusted. While wearing the loupe, close the left eye and look through the right lens to align it with the left stereoscopic paired photograph.
A Fiberoptic Slit-Lamp Attachment David Lobel, M.D.
Tel Aviv University.
Inquiries to David Lobel, M.D., Tel Aviv University, Chaim Sheba Medical Center, Goldschleger Eye Research Institute, Tel-Hashomer 5261, Israel.
I have developed a simple way to attach a fiberoptic lightguide to the light source of a conventional slit lamp (Figure). This method provides a high-quality, easily manipulated, and versatile light source. It has proven especially useful for eyelid and scleral transillumination and in anterior segment photography. This adaptation requires few additional parts and does not alter the quality or intensity of the primary light source in any way. The attachment was made by first drilling a 6-mm hole in the light housing of a slit lamp at the level of the filament. One end of the light guide was inserted into this hole. A parabolic reflector of polished aluminum was mounted on the inside of the lamp housing opposite the hole so that light converged toward the opening. The lightguide is held in place by a metallic ring encircling the lamp housing and holds the fiberoptic lightguide in place by the use of one
TABLE
References
SULFONAMIDE·INDUCED CHANGES CHANGES
R.E.
LE.
Total induced myopia (diopters)
4.00 0.27
3.00 0.28
Lens thickening (mm) Myopia caused by lens thickening
3.46 87 0.25
Diopters
% of total Anterior lens displacement (mm) Myopia caused by anterior lens displacement Diopters
0.54
13
% of total
2.57
86 0.21 0.43 14
In this condition cycloplegia does not change the induced myopia. Finally, in transient myopia caused by accommodative spasm, the entire myopic change is eliminated with cycloplegia and no anterior movement of the entire lens is present. A combination of cycloplegic refraction and ultrasonographic A-scan measurement of lens position allows the underlying mechanism in transient myopia to be determined and aids in the differential diagnosis. For easy reference a flow diagram is shown in the Figure.
1. Fraunfelder, F. T.: Drug-induced Ocular Side Effects and Drug Interactions, 2nd ed. Philadelphia, Lea and Febiger, 1982, pp. 40-43, 359-361, 461, and 462. 2. Bovino, J. A., and Marcus, D. F.: The mechanism of transient myopia induced by sulfonamide therapy. Am. J. Ophthalmol. 94:99, 1982. 3. Chirls, I. A., and Norris, J. W.: Transient myopia associated with vaginal sulfonilamide suppositories. Am. J. Ophthalmol. 98:120, 1984. 4. [arnpolsky, A., and Flan, B.: Transient myopia associated with anterior misplacement of the crystalline lens. Am. J. Ophthalmol. 36:81, 1953. 5. Kimura, R., Kasi, M., Shoji, K., and Kanno, c.. Swollen ciliary processes as an initial symptom in Vogt-Koyanagi-Harada syndrome. Am. J. Ophthalmol. 95:402, 1983.
Myiasis Palpebrarum Kirk R. Wilhelmus, M.D. Ocular Microbiology Laboratory, Cullen Eye Institute, Baylor College of Medicine. This study was supported in part by grants from the Sid W. Richardson Foundation and Research to Prevent Blindness, Inc. Inquiries to Kirk R. Wilhelmus, M.D., 6501 Fannin St., Houston, TX 77030.
Transient Myopia
-
Yes Reversal with Cycloplegia
Normal Accommodation Ciliary Spasm Accomodative Spasm
No Anterior Movement of Posterior Lens Vertex No
April, 1986
AMERICAN JOURNAL OF OPHTHALMOLOGY
-
Yes
Ciliary Body Edema: Sulfas Vogt-Koyanagi-Harada's Isoniazid
It
Lenticular Edema: Diabetes Mellitus Uremia
Figure (Hook and associates). Flow diagram for differentiating causes of transient myopia.
The most common cause of cutaneous maggot infestation in humans is the botfly, Dermatobia hominis, found in the tropical regions of Central and South America. Ophthalmomyiasis is infrequent, representing less than 5% of all sites, although eyelid involvement is possible!" and can be misdiagnosed as bacterial preseptal cellulitis. I examined a woman in Cali, Colombia, who had palpebral myiasis. She recalled an insect bite on the right upper eyelid a few weeks previously. Swelling and pruritus gradually developed. As the discomfort increased, she began having intermittent crawling and wriggling sensations under the skin. In addition to eyelid cellulitis and lymphangiitis (Fig. 1), there was an aperture with a small amount of hemoserous discharge. After gentle probing, this produced a retractile structure. Petrolatum ophthalmic ointment was applied to the punctal lesion, and shortly afterwards the posterior end of a maggot appeared and
Vol. 101, No. 4
Letters to The Journal
Fig. 1 (Wilhelmus). Eyelid cellulitis with a small pore through which the caudal end of a maggot intermittently appeared. was grasped with toothed forceps. Because the opening apparently needed enlarging, 2% lidocaine was locally injected whereupon the parasite stopped moving and was gently extracted (Fig. 2). The bristling, backward-directed black spicules on the third-instar larva's anterior segment made removal somewhat difficult. After local irrigation of the subcutaneous cavity, the patient healed satisfactorily within the next week. How human parasitism by D. hominis comes about is peculiar. 5 Living mainly in the transequatorial, coffee-growing, wooded highlands of tropical America (18 S to 25 N) adult botflies, which resemble bumble bees, are rarely seen,
Fig. 2 (Wilhelmus). Late-stage Dermatobia hominis larva, 15 mm in length, removed from eyelid lesion. Note black spines on anterior segments.
497
living only to mate and never feeding. Copulation is initiated by aggressive male pouncing behavior related to visual stimuli toward the female. Subsequently, the female oviposits her eggs during daylight onto a captured, flying, hematophagus insect like a Psorophora mosquito, gluing them onto the lateral or ventral side with a water-insoluble, quick-drying cement that avoids interference with the vector's flight efficiency. Attached by their posterior ends, the eggs are transported by the carrier insect. When in contact with a warm-blooded host, usually cattle but sometimes humans or various domestic and wild animals, the eggs hatch when stimulated by a sudden temperature increase when the porter insect alights. A l-rnrn first-stage larva emerges through the egg's anterior operculum pointed toward the skin where it can enter via the vector's puncture wound or painlessly chew through intact skin within several minutes. After burrowing into the subcutaneous tissue, the larva, or bot, molts twice through three stages called instars over the next four to 18 weeks. A local furuncular lesion, or warble, forms after two to three weeks with a skin opening acting as a respiratory pore so that the maggot's caudal pair of spiracles can provide an adequate air supply. Staying close to the wound's surface, el t6rsalo (from the Spanish torcer, to twist) intermittently moves within the skin cavity, especially at night. A few may die and produce a chalazionlike lesion, but in the proper host the larva eventually backs out with peristaltic contractions through the breathing orifice during the early morning to drop to the ground where it actively buries itself in the surface soil for a four- to l l-week pupation. The adult flies mate within one day and live for only about one week. Fossils resembling D. hominis have been traced to the Paleocene period, 60 million years ago, and these flies have been studied for three centuries. No one has yet acquired D. hominis infestation within the United States, but imported cases have been reported since work began on the Panama Canal. Most have occurred on the arms and legs; cutaneous myiasis of the head appears to be relatively uncommon. Because these cuterebrid eggs are usually transported by mosquito carriers, an insect repellant should offer protection in the indigenous zones. The treatment of ophthalmomyiasis externa is relatively straightforward once the correct diagnosis is made.
498
AMERICAN JOURNAL OF OPHTHALMOLOGY
References 1. Negro, R. c., Ferrer, J., Osimani, J. J., and Galli, M. A.: Oftalmomiasis por Dermatobia hominis. Arch. Pediatr. Uruguay 40:60, 1969. 2. Lopez, M., and Arrivillaga, R.: Miasis ocular. Rev. Oftalmol. Venez. 27:185, 1971. 3. Cordero-Moreno, R.: Etiologic factors in tropical eye diseases. Second American Journal of Ophthalmology and Pan American Association of Ophthalmology Lecture. Am. J. Ophthalmol. 75:349, 1973. 4. Ruggiero, G., Galiano, P., DiDeco, M., and Biava, G. L.: Secao de doencas externas oculares da faculdade de medicina de jundiae. Rev. Bras. Oftalmol. 40:325, 1981. 5. Carts, E. P.: Biology of New World bot flies. Cuterebridae. Ann. Rev. Entomol. 27:313, 1982.
A Simplified Method for Viewing Slides Stereoscopically
April, 1986
The head is held still and the left lens is aligned on the right paired photograph in the same way. When both eyes are open, the two photographs can be viewed stereoscopically. Once properly adjusted, the loupes do not need to be altered. Nonstereoscopic slides can be examined with the same loupes or at a higher magnification with x4 loupes at a 14-cm working distance. This gives approximately the same magnification as a standard 25-diopter hand viewer. I believe this method will be of general interest and I am not aware of it being described previously. I helieve it greatly facilitates the reading of slides. It offers improved comfort, a better working distance, a greater depth of focus, and the ability to find a particular photograph or to scan photographs more rapidly as well as clear peripheral vision, which is useful when making notes and finding slides. It works well for single slides, slides mounted in plastic holding sheets, or strips of film. I trust others will be spared hours of discomfort and fatigue by using this easy method.
Hugh R. Taylor, M.D.
International Center for Preventive and Epidemiologic Ophthalmology, Wilmer Institute, Johns Hopkins University. Inquiries to Hugh R. Taylor, M.D., Wilmer Institute, Johns Hopkins Hospital, Baltimore, MD 21205.
Sometimes it is necessary to examine large numbers of slides, such as fundus photographs, fluorescein angiographs, or photographs for cataract or trachoma grading. The standard method for either carefully grading or merely scanning these slides is to place them on a light box and to use a small hand magnifier or stereoscopic viewer. This is tiresome, tedious work and requires long hours of working over a light box with your face only inches from the work surface. Alternatively, + 10-diopter aphakic spectacles can be used but they again dictate a short working distance and distant peripheral vision. Recently, I tried an alternate method of reading slides using a standard spectacle magnifying loupe. Stereoscopic paired slides can be easily viewed stereoscopically by correctly adjusting the loupes as the x2.5 Oculist loupe on which the individual telescopes are individually adjusted. While wearing the loupe, close the left eye and look through the right lens to align it with the left stereoscopic paired photograph.
A Fiberoptic Slit-Lamp Attachment David Lobel, M.D.
Tel Aviv University.
Inquiries to David Lobel, M.D., Tel Aviv University, Chaim Sheba Medical Center, Goldschleger Eye Research Institute, Tel-Hashomer 5261, Israel.
I have developed a simple way to attach a fiberoptic lightguide to the light source of a conventional slit lamp (Figure). This method provides a high-quality, easily manipulated, and versatile light source. It has proven especially useful for eyelid and scleral transillumination and in anterior segment photography. This adaptation requires few additional parts and does not alter the quality or intensity of the primary light source in any way. The attachment was made by first drilling a 6-mm hole in the light housing of a slit lamp at the level of the filament. One end of the light guide was inserted into this hole. A parabolic reflector of polished aluminum was mounted on the inside of the lamp housing opposite the hole so that light converged toward the opening. The lightguide is held in place by a metallic ring encircling the lamp housing and holds the fiberoptic lightguide in place by the use of one