fundus examination that will be performed with the use of specialized equipment.
Patients with cataracts may have a diminished or missing red reflex. To obtain the best visualization of the fundus, the size of the aperture may be reduced in order to minimize light scattering. It may not be possible to visualize the fundus in patients with dense cataracts. Patients with dense cataracts should be evaluated by an ophthalmologist.
Troubleshooting
Although the funduscopic examination is challenging for beginners, it becomes easier with practice. Familiarize yourself with the ophthalmoscope before examining patients. When examining patients, dim the room lights to maximize the dilatation of the pupils and improve the visual contrast of the fundus. First elicit the red reflex, since the red reflex indicates successful illumination of the retina. To locate the optic disk, approach the patient at an angle of about 15 degrees temporal to center; if the retina is not visualized, make small adjustments in the angle relative to the patient's visual axis.
Technological advances include the development of instruments that facilitate examination of the retina by nonophthalmologists. Some of these devices contain cameras. However, these new devices are not yet widely available.
Summary
Direct ophthalmoscopy is an important technique for examination of the retina that can be mastered with practice. It can be performed in minutes during the general medical examination and poses virtually no risks to the patient. Ophthalmoscopy allows the general practitioner to evaluate the retina for pathologic changes, particularly in patients with common systemic diseases such as diabetes, hypertension, or atherosclerosis. Ophthalmoscopy can also help to identify ophthalmic emergencies that require immediate attention.
Supported by the State Key Laboratory of Ophthalmology and Zhongshan Ophthalmic Center, Sun Yat-sen University, and grants from the 973 Program (2015CB94600 and 2012CB917304).
Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.
No potential conflict of interest relevant to this article was reported.
SOURCE INFORMATION
From the Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China (Y.L., L.L., K.Z.); and the Shiley Eye Institute and Institute for Genomic Medicine, University of California at San Diego, La Jolla (F.W., D.L., K.Z.).