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lntraoral and intranasal photography using a retinal fundus camera

L. M. MERIN AND R . A. MILLS

Like other subspecialities in biomedical imaging, clinical oph- thalmic photography requires specialized instrumentation to produce informative photographs. Photographic slit-lamps, external ocular cameras, and retinal fundus cameras each have optical and illumination components that are designed to yield optimal results within narrow subject contexts. A variety of ophthalmic pathologies are associated with lesions in other parts of the body. One disease, cicatricial pemphigoid, causes changes in the mucosal tissue of the nasal and oral passages in addition to conjunctival findings. Lacking endoscopic instru- mentation, we capitalized on the design parameters of a retinal fundus camera to produce photographs of these remote lesions.

Routine services provided by the typical innovative ways far removed from their The following example illustrates how ophthalmic photographic laboratory intended purpose. Although the result- we used a standard retinal fundus camera include retinal fundus photography, ing photographs may not match the to complete an unusual assignment. fluorescein angiography. slit-lamp bio- quality of those customarily produced micrography and external ocular photog- by the instrument, they may nonetheless raphy'. Except for the latter technique. provide useful images for teaching pur- each of these clinical assignments uti- poses and to augment the medical .4 31-year-old man was referred to the lizes photographic instrumentation of record. photographic laboratory with the diag- 'task-specific' design. Typically, cam- eras used for such ophthalmic assign- ments are mounted on heavy stands and incorporate an apparatus to support the patient's head. Hence, such equipment can produce optimal image quality only within narrow subject contexts.

A variety of ocular pathologies are associated directly with changes in other parts of the body. Documentation of lesions that are remote from the ocular locus often requires specialized equip- ment that may not be readily available in an eye clinic.

When confronted with such an assignment, ophthalmic photographers may be forced to employ cameras in

Materials and methods

Lan r w c e M . Merin RBP FIMI FOPS i s at the J o r i r s Eye Institute. University ($ Arkansas for Mrilic.ul Sciences, 4301 West Markham. Mail Slot #523. Little Rock, Arkansas 72205 USA. unrl Richard A. Mills M D is at the D ~ ~ , ~ ~ ~ ~ ~ , ~ ~ , ~ ~ ~f Ophthalmology, puren ~ l i ; . aherh Hmpi ta l . Adelaide, Australia

Figure 1 The primary ophthalmic manifestation of mucous membrane pemphigoid is ulceration and scarring of the conjunctiva. These lesions were photographed with a Zeiss photo slit-lamp

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nosis of mucous membrane or cicatricial pemphigoid. Because the involvement of multiple mucosal surfaces (chiefly the eye and mouth) is a necessary feature of the diagnosis of this disease2,’, we obtained slit-lamp photographs of sev- eral ulcerative lesions of the tarsal con- junctiva. We also attempted to photo- graph the scarring and ulceration of the mucous membranes in his nose and mouth.

The conjunctival photographs were produced with the Zeiss photo slit-lamp (Zeiss, Oberkochen, Germany) and, since this is a routine application, the photographs depict accurately the clin- ical condition (Figure I).

The intranasal and intraoral photo- graphs were more problematic. Our external ocular photography apparatus consists of a small electronic flash unit attached with a rotating bracket to the front of a 90-mm macro lens‘. This apparatus could not produce true coaxial lighting required for adequate illumina- tion of these two anatomic cavities. Our flash lacks a modelling light, and we felt that this would not only prevent accurate focusing, but also meant that we could not predict accurately the boundaries of the illuminated field.

Although we could configure the photo slit-lamp to yield coaxial lighting’, the fixed plane of focus of this instru- ment is a constant 105 mm from the front surface of the objective lens. For intra- oral views, this would have resulted in the patient’s lips touching the lens.

Fundus cameras, however, are designed to yield coaxial lighting‘. Cus- tomarily, these cameras form an image of the retina by maintaining a working distance of 50 mm from the objective lens to the cornea, although Lubkin’ and Wong’ have reported on the camera’s ability to photograph the front portion of the eye by shifting the focus anteriorly. Two earlier reports cite the use of a portable fundus camera, as opposed to the conventional stand-mounted instru- ment, for photographing nonophthalmic subjects”.”. Furthermore, we recalled how some retinal patients mistakenly respond to the photographer’s command ‘Open wide’ by opening their mouths instead of their eyes. With these attri- butes in mind, we selected our Canon CF-60U fundus camera (Canon, Kawa- saki City, Japan) to produce the cavity photographs (although recent vintage Topcon, Kowa, Nikon and other fundus cameras that incorporate a ‘plus’ dioptre accessory lens may also be used for this application).

Figure 2 With the ’plus‘dioptre lens in position, intraoral photographs may be produced. The camera‘s conventional chin and forehead support fixture is not used, since it would limit the ability to pose the patient. The reflex viewing feature of retinal fundus cameras is used to obtain optimal subject-to-camera distance, composition, and focus

We hypothesized that some combina- tion of increased flash power and increased film sensitivity would be required to overcome the attenuation of light caused by the increased distance to the subject. Instead of the IS0 50 colour film we customarily used for retinal photography, we chose Kodak Ekta- chrome 200 film (Eastman Kodak, Rochester, New York, USA). We brack- eted extensively by manually changing the IS0 setting on the flash control panel. After reviewing the processed transparencies, we determined that the proper exposure was obtained with the power supply set to IS0 25. This indi- cated that these extraocular lesions required an exposure increase of three f-stops when compared with retinal pho- tography. (Because light transmission through fundus cameras is variable, each camera should undergo individualized testing to determine optimal exposure parameters.)

We set the fundus camera to its ‘plus’ dioptre setting to allow focusing on to a distant plane. Because photophobia was not a concern, we set the modelling lamp to its highest output. The patient was positioned in front of the lens, but the typical two-point head support mecha- nism could not be used (Figure 2 ) . The lesions were seen easily through the camera viewfinder. After adjusting the

patient’s position and utilizing a wooden tongue depressor to obtain the clearest view of the mucosal surface, we pro- duced several photographs. A procedural note of interest was that the patient’s exhalation tended to fog the objective lens during intraoral photography. The clearest photographs were made while the patient inhaled.

The intranasal views were produced in similar fashion. Because the lesions were quite anterior, we were not forced to use a nasal speculum (another instrument not typically found in an ophthalmology department). Since the original slides depicted an oval image typical of retinal photographs, the slides were duplicated with increased image magnification to produce the final rectangular format (Figure 3).

Summary

On occasion, specialized ‘task-specific’ biomedical photographic instruments may be used in ways quite different from their intended application. This report describes how a retinal fundus camera was used to produce intraoral and intra- nasal photographs. By extrapolation, one may expect that successful imaging of details within other body cavities, such as the uterine cervix, may be produced with similar techniques.

24 Mrrin and Mills

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References

1. Hurtes R. Evolution of ophthalmic photography. In: Justice JJ, ed. Oph- thalmic Photography. Boston: Little, Brown and Company, 1982: 1-18.

2. Frith PA, Venning VA, Wojnarowska F et al. Conjunctival involvement in cicatricial and bullous pemphigoid: a clinical and immunopathological study. Br J Ophthalmol 1989; 73:

3. Hunter PA, Watson PG. Allergic eye diseases, episcleritis and scleritis. In: Spalton DJ, Hitchings DJ, Hunter PA, eds. Atlas of Clinical Ophthalmology. London: Mosby-Year Book Europe Lim- ited, 1994: 5.8-5.12.

4. Merin LM. Ophthalmic photo- graphy. In: Vetter JP, ed. Biomed/cal Photography. Stoneham: Butterworth- Heinemann, 1992: 333-58.

5. Meyner E-M. Atlas der Spaltlam- penphotographie. Stuttgart: Ferdinand Enke Verlag, 1976.

6. Gutner R, Miller D. Inside the fun- dus camera. Ann Ophthalmoll983; 15:

7. Lubkin V. Photography of the red reflex. Arch Ophthalmol 1950; 43: 718.

8. Wong D. Techniques of fundus photography. In: Biomedical Photo- graphy, a Kodak Seminar in Print. Rochester: Eastman Kodak 1976:

52-6.

13-16.

38-59.

9. Jeffreys N. Kowa retinal camera used for cavity photography. Medical and Biological Illustration 1966; 16: 200.

10. Morton R, Munro A. Photoprocto- Figure 3 The Canon CF-GOU retinal fundus camera was used to produce the scopy with the Kowa fundus camera. intranasal (top) and intraoral (bottom) photographs, shown here following Medical and Biological Illustration slide duplication wi th 50% enlargement of the images 1975: 25: 102-3.

The Jounml ofAudiovisua1 Media in Medicine (1 995) Mil . 18/No. I 25

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