Ординатура / Офтальмология / Английские материалы / Practical Ophthalmology A Manual for the Beginning Ophthalmology Residents 4th edition_Wilson_1996
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Diagram the Confrontation Field
7. If an abnormality is detected, sketch a 360° visual field chart, labeled for right and left eye and temporal and nasal field, and plot the visual field as the patient sees it (Figure 1). Record a failure to detect an abnormality as "no defect to finger confrontation."
Figure 1
Clinical Protocol 8.2
Performing the Amsler Grid Test
Test Setup
1.With the patient wearing appropriate reading spectacles or trial lenses for near correction, ask the patient to hold the testing grid perpendicular to the line of sight, approximately 36 mm (14 inches) from the eye.
Check for Scotoma
2. Ask the patient to fixate steadily at the central spot of the grid.
3.Ask the patient whether all lines are straight and all intersections are perpendicular and if any areas of the grid appear distorted or missing.
Diagram the Test Result
4.Have the patient draw the area of visual distortion or loss on the preprinted Amsler grid notepad (see Figure 8.3B). Be sure to note the patient's name, the eye being tested, and the date on the recording chart. Test both eves and record all results, whether abnormal or not.
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Performing the Tangent Screen Test
Test Setup
1.Seat the patient 1 m from the tangent screen. The eye being tested should be in line with the central fixation target. Check regularly and often to ensure that the patient is maintaining central fixation.
2.The patient should wear his or her regular corrective distance lenses. Occlude completely the eye not being tested.
3.Dim the room sufficiently so the black wand blends with the background of the tangent screen.
Identify and Outline the Blind Spot
4.Instruct the patient to fixate on the central target. Explain that you will be moving a white dot in and out of the patient's view and that the patient is to tell you when it is or is not visible by saying "on" each time that the target comes in sight and "off when it disappears. Patients can also tap a coin on the arm of the examination chair or click a metal cricket to indicate "on."
5.Stand to the far side of the screen temporal to the patient's test eye. Slowly and smoothly move the test object from the patient's temporal field and along the horizontal meridian toward the center of the screen until the patient reports it disappears (usually at about 15° temporal to fixation). This identifies the outer edge of the blind spot.
6.Memorize the boundaries of the patient's blind spot by moving the target from this "off" area to the surrounding area, using vertical, horizontal, and oblique movements, with the patient stating at each point when the object reappears. The faint oval on the tangent screen serves as your guide to the expected size of the blind spot.
Outline the Central Field
7.Remain standing to the far side of the screen temporal to the patient's test eye. Beginning off the screen, slowly move the target onto the screen along the horizontal meridian. As soon as the patient indicates the target is visible, twirl the wand so the object is black and retract it off the screen. Use slow, smooth, steady movements when maneuvering the wand and target disc against the screen.
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8.Test the nasal visual field. Move the target along each of the nasal oblique meridians that radiate from fixation at 30° intervals. Make a mental note of the isopter boundary.
9.Move the target along the vertical meridian, from above and from below.
10.Test the temporal visual field. Walk to the other side of the screen (the side of the screen nasal to the patient's test eye). Move the target along the temporal meridians in a similar manner as before.
Check for Hemianopia and Other Scotomas
11.Check for a hemianopic defect by moving the target parallel to the horizontal meridian. Slowly move the target across the vertical meridian, first from one direction then from the other. Position yourself so that the wand does not cross the central fixation target.
12.Check for a scotoma in the intermediate or cecal zones. After the patient reports seeing the object at the periphery, continue to move it along the meridian toward fixation. Instruct the patient to report, while you do this, whether the dot disappears at any point.
a.If you suspect a scotoma, confirm its presence by holding the test object stationary and asking whether or not the patient sees it.
b.Once a scotoma is confirmed, outline its boundaries by moving the test object perpendicularly from the nonseeing area until the patient reports the object becomes visible.
c.If the scotoma is very small or subtle, switch to a 1 mm test object or use a colored (red, green, or blue) target.
Confirm Test Consistency
13.If you suspect functional visual loss, repeat steps 7-9 at 2 m using a target twice as large.
Diagram the Tangent Screen Map
14.Label the visual fields chart with the date, examiner, the patient's corrected visual acuity (noting whether the patient wore corrective lenses or not), and the patient's cooperation and alertness.
15.Label the chart with the diameter and color of the test object and the distance between the patient and the screen. For example, 10YV/1000 indicates a 10 mm diameter white disc or sphere presented at 1 in (1000 nun). To transpose target size into degrees, use the following formula:
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distance (m) |
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16. Record the findings of the test from memory. Draw the boundary of the visual field for a given target as a solid line. Draw the blind spot and shade it. Draw any scotoma and shade it.
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Clinical Protocol 8.4
Performing Goldmann Perimetry
Test Setup
1.Ensure that the machine has been properly calibrated. Set the target size and brightness; most visual field tests begin with I4e.
2.Begin the examination without the patient wearing spectacles (because their frame interferes with seeing the peripheral visual field). Insert the patient's corrective spherical lens for near vision into the trial lens holder.
3.With the patient's chin in position on the chin rest, secure the head band around the patient's head.
4.Explain to the patient that it is important to stare directly ahead at the central dark spot.
5.Insert the perimetry chart on your side of the perimeter and secure it with the knobs. Make sure the horizontal line on the right side of the chart is aligned with the corresponding V-shaped notch.
6.Look through the eyepiece and center the patient's eye on the crosshairs by adjusting the headrest with the knob. Throughout the test, periodically check to make sure the patient is fixating on the central target.
7.Measure and record the pupillary diameter using the reticule in the eyepiece.
8.Instruct the patient to press the buzzer as soon as a spot of light is seen. Demonstrate by briefly opening and closing the shutter at three different spots within the central field to make sure the patient signals correctly-
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Identify and Outline the Blind Spot
9. With near correction in place, extinguish the I4e target with the shutter control, place it 15° temporally, reilluminate it, and move it outward in different directions until you have fully defined the physiologic blind spot. This procedure can be repeated with the 12e target to confirm the location of the blind spot.
Outline the Central Field
10.Beginning in the nonseeing periphery, move the I2e target at 2° per second toward fixation.
11.Test each radial meridian, choosing one at random, by moving the target across the peripheral boundary of the visual field. Mark the isopter boundary on the paper chart with an X at each 15° meridian as it is tested.
Check for Scotoma
12.Perform supra threshold static perimetry by turning the 12 e target on for about 1 second at multiple locations within the central zone. Check
every meridian around the 10° circle of eccentricity.
a.For suspected glaucomatous optic neuropathy, concentrate on the central 20° and on the zone slightly above and below the nasal horizontal meridian.
b.For suspected chiasmal or retrochiasmal disease, concentrate on testing both sides of the vertical meridian.
13.Place a dot where the target is correctly seen, and draw a circle at each missed target. Plot any scotoma that is found by moving the target from nonseeing to seeing areas perpendicular to the scotoma's boundaries. Sometimes the patient can perceive movement within a field defect before seeing the light (Riddoch phenomenon).
Outline the Intermediate or Peripheral Field
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Remove the corrective lens. |
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To test the peripheral zones by kinetic perimetry, use the I4e target (or |
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a larger target if the field is severely depressed). Move the continuously illuminated target at a constant speed of 2° per second from the nonseeing periphery toward the center along the meridians every 15°. Mark the threshold (the point at which the patient reports the target becoming visible) on the chart with an X.
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a.Check for a nasal step field defect in patients with glaucoma by moving the target across the horizontal meridian, first from below and then from above, within the outermost portion of the nasal visual field.
b.Check for a hemianopic defect in patients with an intracranial lesion by moving the target across the vertical meridian, first from the nasal field then from the temporal field, within the outermost portion of the superior and inferior visual field.
Diagram the Goldmann Chart
16. On the standard chart, draw each isopter with a smooth, curved line
...,v-.(Figure 1). Fill in any scotoma. Target data are usually recorded with different colors for different targets (eg, blue for the T4e target, red for the 12e, and black for the V4e).
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External Examination
he external ocular examination consists of a three-part stepVise sequence that focuses the examiner's senses on the patient: inspection (looking); palpation (feeling); and auscultation (listening). These methods are accompanied by specific clinical measurements as necessary. A fixed sequence of examination steps helps ensure that the examiner has covered all anatomic details and physiologic functions of the external eye. With experience, screening a patient's external features will occur almost automatically. The patient's history and appearance should lead the examiner to the appropriate testing techniques, so the many available examination tasks described in this chapter need not be applied in their entirety7 to every patient.
A thoughtful and thorough external examination is the first step in the physical evaluation of a patient's complaint. It can yield considerable information that directs the course of the rest of the examination. This chapter details the application of the three principal steps in the external ophthalmic examination and pro-
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174 Chapter 9: External Examination
vides instruction in a variety of measurement and evaluation techniques
that are commonly used in this part of a comprehensive ophthalmic
examination.
Situating the Patient
The patient usually sits in the examining chair for the examination. Young children often do well sitting on their parent's lap. An uncooperative infant or toddler can be laid flat on a bed or padded table and immobilized by having the parent hold the child's upstretched arms firmly against the sides of the child's head while leaning against the child's legs and body. Very young infants can be swaddled (Figure 9.1).
General Observation
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Before the detailed external ocular examination begins, die examiner |
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usually conducts a brief visual survey of the entire patient, being atten- |
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tive for signs of medical, dermatologic, and neurologic disease. This |
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general physical observation may occur during casual pre-examination |
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conversation or history taking. By observing the patient's specific |
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actions and appearance, especially die facial features around the eyes, |
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die examiner may find clues to die patient's attitude, overall well-being, |
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and general physical or ocular problem. Sometimes an examiner can |
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recognize a disease pattern by an initial intuition. Other times, the his- |
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tory will direct the examiner's attention to a specific abnormality. |
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Observing the patient in a lighted room before the stepwise ocular |
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inspection gives many clues to anatomic deformities and illness. |
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During this observation, note the patient's demeanor, mental status, |
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complexion, and apparent nutritional health, along with any abnormal |
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movements, disabilities, or stigmata. Some conditions with obvious |
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features are quickly recognizable, such as albinism and Down syn- |
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drome. The extremities, especially the hands, can give clues to svs- |
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temic diseases, such as rheumatoid arthritis. Focusing on the lace and |
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ocular adnexa can reveal skin conditions, >>iicli as rosacea, and other |
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disorders that can allect the eves. |
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Inspection |
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Figure 9.1 How to bundle a baby for an eye examination. (A) Fold a sheet into an equilateral triangle and lay the supine infant on it, with the infant's head just above the top edge. (B) Fold one side over the infant to pin one arm against the body, tucking the edge of the sheet under the child's body and tucking the bottom flap of the sheet up over the baby's feet. (C) Hold the other arm against the baby's side while pulling the other edge over the baby's body and tuck the edge underneath the child.
Inspection
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The inspection is a visual survey of the external eye and, like the gen- |
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eral observation, often begins while talking to the patient. The basic |
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equipment for the external examination should be readily available |
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(Table 9.1). Clinical measurements that are taken during the external |
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examination are assessed for symmetry and compared with expected |
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values. Each visible or palpable mass is measured in the longest dimen- |
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