The three general types are external, slit-lamp, and fundus photography. Each type is named for the part of the eye it records. External photography records the outer structures, such as the eyelids. Slit-lamp photography records the front of the eye through the slit lamp. Fundus photography records the retina and optic nerve at the back of the eye. All three now use digital camera bodies.
Each type needs different gear. External photography needs only a digital camera with a close-up lens and an electronic flash. It is used for problems that can be seen without much magnification. For slit-lamp work the camera attaches to the slit lamp, and the slit lamp's optics replace the camera lens. That gives the magnification needed for the cornea, angle, iris, and lens. The fundus camera acts like a large ophthalmoscope. It holds a viewing system, a light and flash system, and a digital camera. Patients get dilating eyedrops first, so the camera gets the widest view of the fundus. The fundus camera also takes the black-and-white images used during dye studies of the retinal blood vessels. Color fundus images can be printed from the digital file.
Sort the three types by location: outside the eye, the front of the eye, and the back of the eye. Then pick the camera that answers the doctor's question. If the finding is on the lid, go external. If it is in the cornea or iris, go to the slit lamp. If it is in the retina, go to the fundus camera. Naming the types of eye photography and their uses belongs to the COA ophthalmic imaging content area.
Incorrect Answers
- A. Contrast sensitivity and perimetry are vision tests, not cameras. Perimetry maps the field of vision, and neither test makes a picture of the eye.
- C. Tonometry measures the pressure inside the eye, and ultrasonography uses sound waves instead of light. Only slit-lamp photography in this list is a type of photography.
- D. Keratometry measures the curve of the front of the cornea in diopters. It reports numbers, not photographs, so it is not one of the three types.
Testing Pearls
- The three types of eye photography are external, slit-lamp, and fundus.
- External photography needs only a close-up lens and a flash.
- At the slit lamp, the slit lamp's optics do the focusing and magnifying.
- The fundus camera images the retina and optic nerve through a dilated pupil.
- All three types record on digital camera bodies today.
References
- American Academy of Ophthalmology. Ophthalmic Medical Assisting: An Independent Study Course. Chapter 10, Adjunctive Tests and Procedures.
