An ophthalmoscope is an instrument used by doctors, ophthalmologists and optometrists to view the inside of the eye, particularly the back, or fundus, of the eye. The ophthalmoscope uses a bright light, lenses and mirrors to magnify areas of the eye so that problems due to disease or injury can be determined.
Types
The University of Kansas Medical Center explains that there are two types of ophthalmoscopes: Direct ophthalmoscopes are common, hand-held instruments used in physician clinics to view the inside of the eye. Indirect ophthalmoscopes are typically larger and may be worn on the head of the examining physician and are used simultaneously with a separate hand-held lens for a detailed and expanded view of the eye. Optometrists and eye specialists most often use indirect types.
Preparation
The patient is asked to remove her glasses and the lights in the examining room can be dimmed or turned off. The patient is also advised that a bright light will be used to view the inside of her eyes. The Student BMJ advises that the patient should look at a single point on the wall behind the doctor so that she is gazing directly at the light.
Pupil Dilation
The Student BMJ notes that in some cases, it may be necessary to dilate the pupil in order to effectively view the structures inside the eye. This is particularly important in patients with eye or neurological problems who may have incorrectly dilating pupils. A medicinal eye drop of 1 percent tropicamide is administered in each eye 15 minutes before the examination. However, in the majority of patients, the drops are not needed and the pupils dilate normally in the dimmed room.
Examination
For best results, doctors use their own left eye to examine the patient's left eye and right eye to examine the patient's right eye. The doctor keeps both eyes open while placing his hand on the patient's forehead to keep it still. The doctor may gently use his thumb to keep the patient's eyelid open while the light is shined into the patient's pupil. The first part of the eye that is viewed is the pupil itself and a superficial view will determine whether both pupils dilate equally. The doctor will see a red reflex in the eye and the optic disc. The lens of the ophthalmoscope is adjusted to bring the optic disc into focus. Other structures that are magnified and viewed include the crystalline lens, the retina, or back of the eye, and blood vessels and the optic nerve, as described by the University of Kansas Medical Center.
Diagnosis
An examination of the eyes with an ophthalmoscope allows the doctor to determine both the health of the eyes and the general health of the body. The doctor is able to view arteries, veins and nerves in and behind the eyes in a non-invasive manner. The Student BMJ explains that this is important in determining neurological problems and vision disorders, as well as eye diseases such as glaucoma and macular degeneration. An ophthalmoscope exam can also detect heart disease, hypertension and complications of diabetes such as diabetic retinopathy may also be diagnosed with an ophthalmoscope exam.
