Ординатура / Офтальмология / Английские материалы / Ophthalmology A Short Textbook_Lang_2000

Basic diagnostic equipment for removing corneal foreign bodies and eyelid eversion.

Fig. 1.3 From left to right: Foreign body needle, glass spatula, and Desmarres eyelid retractor.

1.2History

A complete history includes four aspects:

1.Family history. Many eye disorders are hereditary or of higher incidence in members of the same family. Examples include refractive errors, strabismus, cataract, glaucoma, retinal detachment, and retinal dystrophy.

2.Medical history. As ocular changes may be related to systemic disorders, this possibility must be explored. Conditions affecting the eyes include diabetes mellitus, hypertension, infectious diseases, rheumatic disorders, skin diseases, and surgery. Eye disorders such as corticosteroid-induced glaucoma, corticosteroid-induced cataract, and chloroquine-induced maculopathy can occur as a result of treatment with medications such as steroids, chloroquine, Amiodarone, Myambutol, or chlorpromazine (see table in Appendix).

3.Ophthalmic history. The examiner should inquire about corrective lenses, strabismus or amblyopia, posttraumatic conditions, and surgery or eye inflammation.

4 1 The Ophthalmic Examination

4.Current history. What symptoms does the patient present with? Does the patient have impaired vision, pain, redness of the eye, or double vision? When did these symptoms occur? Are injuries or associated generalized symptoms present?

1.3Visual Acuity

Visual acuity, the sharpness of near and distance vision, is tested separately for each eye. One eye is covered with a piece of paper or the palm of the hand placed lightly over the eye. The fingers should not be used to cover the eye because the patient will be able to see between them (Fig. 1.4).

The general practitioner or student can perform an approximate test of visual acuity. The patient is first asked to identify certain visual symbols referred to as optotypes (see Fig. 1.2) at a distance of 5 meters or 20 feet (test of distance vision). These visual symbols are designed so that optotypes of a certain size can barely be resolved by the normal eye at a specified distance (this standard distance is specified in meters next to the respective symbol). The eye charts must be clean and well illuminated for the examination. The sharpness of vision measured is expressed as a fraction:

Examining visual acuity.

Fig. 1.4 The palm of the hand is placed lightly over the eye to cover it to allow testing of the distance and near vision in the opposite eye.

actual distance

standard distance ! visual acuity.

Normal visual acuity is 5/5 (20/20), or 1.0 as a decimal number, where the actual distance equals the standard distance.

An example of diminished visual acuity (see Fig. 1.2): The patient sees only the “4” and none of the smaller symbols on the left eye chart at a distance of 5 meters (20 feet) (actual distance). A normal-sighted person would be able to discern the “4” at a distance of 50 meters or 200 feet (standard distance). Accordingly, the patient has a visual acuity of 5/50 (20/200) or 0.1.

The ophthalmologist tests visual acuity after determining objective refraction using the integral lens system of a Phoroptor, or a box of individual lenses and an image projector that projects the visual symbols at a defined distance in front of the eye. Visual acuity is automatically calculated from the fixed actual distance and is displayed as a decimal value. Plus lenses (convex lenses) are used for farsightedness (hyperopia or hypermetropia), minus lenses (concave lenses) for nearsightedness (myopia), and cylindrical lenses for astigmatism.

If the patient cannot discern the symbols on the eye chart at a distance of 5 meters (20 feet), the examiner shows the patient the chart at a distance of 1 meter or 3 feet (both the ophthalmologist and the general practitioner use eye charts for this examination). If the patient is still unable to discern any symbols, the examiner has the patient count fingers, discern the direction of hand motion, and discern the direction of a point light source.

1.4Ocular Motility

With the patient’s head immobilized, the examiner asks the patient to look in each of the nine diagnostic positions of gaze: 1, straight ahead; 2, right; 3, upper right; 4, up; 5, upper left; 6, left; 7, lower left; 8, down; and 9, lower right (Fig. 1.5). This allows the examiner to diagnose strabismus, paralysis of ocular muscles, and gaze paresis.

Evaluating the six cardinal directions of gaze (right, left, upper right, lower right, upper left, lower left) is sufficient when examining paralysis of the one of the six extraocular muscles. The motion impairment of the eye resulting from paralysis of an ocular muscle will be most evident in these positions. Only one of the rectus muscles is involved in each of the left and right positions of gaze (lateral or medial rectus muscle). All other directions of gaze involve several muscles.

6 1 The Ophthalmic Examination

Evaluating the nine diagnostic positions of gaze.

Fig. 1.5 This examination allows the examiner to diagnose strabismus, paralysis of ocular muscles, and gaze paresis.

1.5Binocular Alignment

Binocular alignment is evaluated with a cover test. The examiner holds a point light source beneath his or her own eyes and observes the light reflections in the patient’s corneas in the near field (40 cm) and at a distance (5 m). The reflections are normally in the center of each pupil. If the corneal reflection is not in the center of the pupil in one eye, then a tropia is present in that eye. Then the examiner covers one eye with a hand or an occluder (Fig. 1.6) and tests whether the uncovered eye makes a compensatory movement. Compensatory movement of the eye indicates the presence of tropia. However, there will also be a lack of compensatory movement if the eye is blind. The cover test is then repeated with the other eye.

If tropia is present in a newborn with extremely poor vision, the baby will not tolerate the good eye being covered.

Evaluation of binocular alignment.

Fig. 1.6 The examiner covers one eye of the patient with the hand to test if the uncovered eye makes a compensatory movement indicating presence of tropia.

1.6Examination of the Eyelids and Nasolacrimal Duct

The upper eyelid covers the superior margin of the cornea. A few millimeters of the sclera will be visible above the lower eyelid. The eyelids are in direct contact with the eyeball.

Stenosis of the nasolacrimal duct produces a pool of tears in the medial angle of the eye with lacrimation (epiphora). In inflammation of the lacrimal sac, pressure on the nasolacrimal sac frequently causes a reflux of mucus or pus from the inferior punctum. Patency of the nasolacrimal duct is tested by instilling a 10% fluorescein solution in the conjunctival sac of the eye. If the dye is present in nasal mucus expelled into paper tissue after two minutes, the lacrimal duct is open (see also p. 53).

Due to the danger of infection, any probing or irrigation of the nasolacrimal duct should be performed only by an ophthalmologist.

1.7Examination of the Conjunctiva

The conjunctiva is examined by direct inspection. The bulbar conjunctiva is directly visible between the eyelids; the palpebral conjunctiva can only be examined by everting the upper or lower eyelid. The normal conjunctiva is smooth, shiny, and moist. The examiner should be alert to any reddening, secretion, thickening, scars, or foreign bodies.

Eversion of the lower eyelid. The patient looks up while the examiner pulls the eyelid downward close to the anterior margin (Fig. 1.7). This exposes the conjunctiva and the posterior surface of the lower eyelid.

8 1 The Ophthalmic Examination

Examination of the lower eyelid and inferior fornix.

Fig. 1.7 The lower eyelid must be everted for this examination. The patient looks up while the examiner pulls the eyelid downward close to the anterior margin.

Eversion of the upper eyelid. Simple eversion (Fig. 1.8). The patient is asked to look down. The patient should repeatedly be told to relax and to avoid tightly shutting the opposite eye. This relaxes the levator palpebrae superioris and orbicularis oculi muscles. The examiner grasps the eyelashes of the upper eyelid between the thumb and forefinger and everts the eyelid against a glass rod or swab used as a fulcrum. Eversion should be performed with a quick levering motion while applying slight traction. The palpebral conjunctiva can then be inspected and cleaned if necessary.

Examination of the upper eyelid (simple eversion).

Fig. 1.8 The patient relaxes and looks down. The examiner places a swab superior to the tarsal region of the upper eyelid, grasps the eyelashes of the upper eyelid between the thumb and forefinger, and everts the eyelid using the swab as a fulcrum.

Full eversion with retractor. To expose the superior fornix, the upper eyelid is fully everted around a Desmarres eyelid retractor (Figs. 1.9a and b). This method is used solely by the ophthalmologist and is only discussed here for the sake of completeness. This eversion technique is required to remove foreign bodies or “lost” contact lenses from the superior fornix or to clean the conjunctiva of lime particles in a chemical injury with lime.

Examination of the upper eyelid and superior fornix (full eversion with retractor).

Figs. 1.9a and b In this case, the examiner everts the eyelid around a Desmarres eyelid retractor. In contrast to simple eversion, this procedure allows examination of the superior fornix in addition to the palpebral conjunctiva.

a

b

10 1 The Ophthalmic Examination

Blepharospasm can render simple and full eversion very difficult especially in the presence of chemical injury. In these cases, the spasm should first be eliminated by instilling a topical anesthetic such as oxybuprocaine hydrochloride eyedrops.

1.8Examination of the Cornea

The cornea is examined with a point light source and a loupe (Fig. 1.10). The cornea is smooth, clear, and reflective. The reflection is distorted in the presence of corneal disorders. Epithelial defects, which are also very painful, will take on an intense green color after application of fluorescein dye; corneal infiltrates and scars are grayish white. Evaluating corneal sensitivity is also important. Sensitivity is evaluated bilaterally to detect possible differences in the reaction of both eyes. The patient looks straight ahead during the examination. The examiner holds the upper eyelid to prevent reflexive closing and touches the cornea anteriorly (Fig. 1.11). Decreased sensitivity can provide information about trigeminal or facial neuropathy, or may be a sign of a viral infection of the cornea.

Examination of the anterior portion of the eye.

Fig. 1.10 The examiner evaluates the eye using a focal light source and loupe magnification.

Evaluation of corneal sensitivity.

Fig. 1.11 Corneal sensitivity can be evaluated with a distended cotton swab. The patient looks straight ahead while the examiner holds the upper eyelid and touches the cornea anteriorly.

1.9Examination of the Anterior Chamber

The anterior chamber is filled with clear aqueous humor. Cellular infiltration and collection of pus may occur (hypopyon). Bleeding in the anterior chamber is referred to as hyphema.

It is important to evaluate the depth of the anterior chamber. In a chamber of normal depth, the iris can be well illuminated by a lateral light source (Fig. 1.12). In a shallow anterior chamber there will be a medial shadow on the iris. The pupillary dilation should be avoided in patients with shallow anterior chambers because of the risk of precipitating a glaucoma attack. Older patients with “small” hyperopic eyes are a particular risk group.

Dilation of the pupil with a mydriatic is contraindicated in patients with a shallow anterior chamber due to the risk of precipitating angle closure glaucoma.

12 1 The Ophthalmic Examination

Evaluation of the depth of the anterior chamber.

Fig. 1.12 a Normal anterior chamber depth: the iris can be well illuminated by a lateral light source. b Shallow anterior chamber: a medial shadow is visible on the iris.

1.10Examination of the Lens

The ophthalmologist uses a slit lamp to examine the lens. The eye can also be examined with a focused light if necessary.

Direct illumination will produce a red reflection of the fundus if the lens is clear and gray shadows if lens opacities are present. The examiner then illuminates the eye laterally with a focused light held as close to the eye as possible and inspects the eye through a +14 diopter loupe (see Fig. 1.10). This examination permits better evaluation of changes in the conjunctiva, cornea, and anterior chamber. With severe opacification of the lens, a gray coloration will be visible in the pupillary plane. Any such light-scattering opacity is referred to as a cataract.