▶ Fig. 2.1 diagrams what is seen on examination of the fundus with a direct ophthalmoscope. ▶ Fig. 2.2 shows a patient being examined with a direct PanOptic (Welsh Allyn, Skaneates Falls, NY) ophthalmoscope, which features a larger field but less magnification than the classic direct ophthalmoscope. Fig. 2.1 a, b (a) Diagram illustrating what is seen on examination using a direct ophthalmoscope. (b) The direct ophthalmoscope allows visualization of the fundus (posterior pole). Fig. 2.2 a, b (a) Diagram illustrating what is seen on examination using a direct PanOptic (Welsh Allyn, Skaneates Falls, NY) ophthalmoscope. (b) The PanOptic direct ophthalmoscope provides a larger field but less magnification than the classic direct ophthalmoscope. The following make direct ophthalmoscopy easier: Get close to the patient. Use your right eye to look into the patient’s right eye, and use your left eye to look into the patient’s left eye. Find the red reflex and get closer until you see the retina. After focusing on the retina, follow the blood vessels toward the patient’s nose to find the optic nerve. To easily find the macula, ask the patient to look into the light. Dilate the pupils to allow easier examination (▶ Fig. 2.3). Fig. 2.3 Only the optic nerve can be seen through an undilated pupil (top), whereas the entire posterior pole can be examined through a dilated pupil (bottom) It is possible to visualize the optic nerve through an undilated pupil. However, it is technically difficult, and it does not allow examination of the entire fundus. Retinal disorders are missed without pupillary dilation. Funduscopic examination includes the optic nerve (specifically, checking for cup-to-disc ratio, edema, and pallor), the retina around the optic nerve, the macula (specifically, checking for color, edema, hemorrhages, exudates, and masses), and arteries and veins (specifically, checking for size, occlusion, and emboli) (▶ Fig. 2.4). Fig. 2.4 a, b (a) Normal fundus (left eye). (b) Normal left optic nerve. Note that veins are larger and darker than arteries (the normal arteriovenous ratio is 2:3). The cup-to-disc ratio (the size of the cup in relation to the size of the disc) should be measured horizontally and vertically (▶ Fig. 2.5). Fig. 2.5 Evaluation of the cup-to-disc ratio in three different patients. The size of the cup is measured in relation to the size of the disc. A small or moderate cup-to-disc ratio (left and middle) is common in normal subjects, whereas a large cup-to-disc ratio (right) is suggestive of glaucoma. Pearls To view the ocular fundus to the best advantage, the pupils should be dilated. To dilate the pupils use a combination of short-acting agents that block parasympathetic transmission (tropicamide) and enhance sympathetic activity (phenylephrine). It also possible to use only one drop. Dilation occurs within 30 minutes and usually resolves within 6 hours. Long-acting dilating drops (used as cycloplegics), such as cyclopentolate, homatropine, and atropine, should not be used to view the fundus (the dilation and cycloplegia may last from 12 hours to up to 14 days). Be sure to alert the patient that driving may be difficult after dilation, especially in bright sunlight. Young patients will have difficulty reading after pharmacologic dilation because of the blockage of accommodation. It is always better to dilate both eyes rather than one eye (a unilateral mydriasis is often alarming, whereas most people will not be concerned about bilateral mydriasis if the patient is awake and alert). Always document the time of dilation and the drops used. Do not dilate a neurosurgical or unstable patient, because monitoring of the pupils may be important. Glaucoma is not a contraindication for pupillary dilation. Patients who know they have a diagnosis of angle closure glaucoma will already have been treated with laser to prevent episodes of angle closure from pupillary dilation and can therefore be dilated without risk. Nearly all patients who say they have glaucoma have open angle glaucoma, which does not contraindicate pupillary dilation. If you are unable to see the fundus on examination, review the following checklist: Is the ophthalmoscope working? (are the batteries charged?) Is the pupil too small? (Did you forget to dilate the patient’s pupils?) Are you sure you know how to use the ophthalmoscope? Is there something blocking the view (media opacity)? Many ocular disorders— corneal disorders, anterior uveitis or hyphema, cataracts, and vitreous inflammation or hemorrhage—decrease the normal transparency of the ocular media, thereby obstructing the view of the fundus (▶ Fig. 2.6). Remember that if you can’t see in, the patient can’t see out. Fig. 2.6 Diagram illustrating how a media opacity can obstruct the view of the fundus.
2.1.1 If You Cannot See the Fundus
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