Ординатура / Офтальмология / Английские материалы / Ophthalmology A Short Textbook_Lang_2000

1.11Ophthalmoscopy

Indirect ophthalmoscopy is usually performed by the ophthalmologist (see p. 306) and produces a laterally reversed image of the fundus. Less experienced examiners will prefer direct ophthalmoscopy. Here, the ophthalmoscope is held as close to the patient as possible (Fig. 1.13; see also Figs. 12.4b and c). Refractive errors in the patient’s eye and the examiner’s eye are corrected by selecting the ophthalmoscope lens required to bring the retina into focus. The examiner sees an erect, 16 power magnified image of the retina. The examination should be performed in a slightly darkened room with the patient’s pupils dilated. Students should be able to identify the optic disk. In a normal eye, it is sharply defined structure with vital coloration (i.e., yellowish orange) at the level of the retina and may have a central excavation. The central vein lies lateral to the artery; venous diameter is normally 1.5 times greater than arterial diameter. Each vascular structure should be of uniform diameter, and there should be no vascular constriction where vessels overlap. A spontaneous venous pulse is normal; an arterial pulse is abnormal. Younger patients will have a foveal and macular light reflex, and the retina will have a reddish color (see Fig. 12.8). An ophthalmologist should be consulted if there are any abnormal findings.

Ophthalmoscopy.

Fig. 1.13 A direct ophthalmoscope produces an erect image of the fundus. The examiner views the patient’s right eye with his or her own right eye so that their noses do not interfere with the examination. The examiner’s right hand rests on the dial of the ophthalmoscope to bring the retina into focus.

14 1 The Ophthalmic Examination

1.12Confrontation Field Testing

Confrontation testing provides gross screening of the field of vision where perimetry tests are not available (see p. 391).

The patient faces the examiner at a standard distance of 1 m with his or her eyes at the same level as the examiner’s (Fig. 1.14). Both focus on the other’s opposite eye (i.e., the patient’s left eye focuses on the examiner’s right eye) while covering their contralateral eye with the palm of the hand. The examiner moves an object such as a pen, cotton swab, or finger from the periphery toward the midline in all four quadrants (in the superior and inferior nasal fields and superior and inferior temporal fields). A patient with a normal field of vision will see the object at the same time as the examiner; a patient with an abnormal or restricted field of vision will see the object later than the examiner.

Confrontation testing is a gross method of assessing the field of vision. It can be used to diagnose a severely restricted field of vision such as homonymous hemianopsia or quadrant anopsia.

Confrontation field testing.

Fig. 1.14 Confrontation test: the patient faces the examiner at a distance of 1 m with his or her eyes at the same level as the examiner’s. Each focuses on the other’s opposite eye while covering their contralateral eye with the palm of the hand. The examiner moves a pen from the periphery toward the midline in all four quadrants in the nasal and temporal fields and in the superior and inferior fields.

Measurement of intraocular pressure.

Fig. 1.15 The examiner uses both index fingers to palpate the eye through the upper eyelid.

1.13Measurement of Intraocular Pressure

With the patient’s eyes closed, the examiner places his or her hands on the patient’s head and palpates the eye through the upper eyelid with both index fingers (Fig. 1.15). The test is repeated on the contralateral eye for comparison.

A “rock hard” eyeball only occurs in acute angle closure glaucoma. Slight increases in intraocular pressure such as occur in chronic glaucoma will not be palpable.

1.14Eyedrops, Ointment, and Bandages

Eyedrops and ointment should be administered posterior to the everted lower eyelid. One drop or strip of ointment approximately 1 cm long should be administered laterally to the inferior conjunctival sac. To avoid injury to the eye, drops should be administered with the patient supine (Fig. 1.16) or seated with the head tilted back and supported. The person administering the medication places his or her hand on the patient’s face for support. Bottles and tubes must not come in contact with the patient’s eyelashes as they might otherwise become contaminated. Allow the drops or strip of ointment to drop into the conjunctival sac.

Eye ointment should not be administered following ocular trauma as this may complicate subsequent examination or surgery. Dilation of the pupils with a mydriatic in unconscious patients should be avoided as this complicates neurologic examination.

16 1 The Ophthalmic Examination

Administration of eyedrops with the patient supine.

Fig. 1.16 Eyedrops should be administered posterior to the everted lower eyelid.

Eye bandage. A sterile swab or commercially available bandage (two oval layers of bandage material with a layer cotton between them) may be used. Care should be taken to avoid touching the side in contact with the eye. The bandage is fixed to the forehead and cheek with strips of adhesive tape.

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2 The Eyelids

Peter Wagner and Gerhard K. Lang

2.1Basic Knowledge

Protective function of the eyelids: The eyelids are folds of muscular soft tissue that lie anterior to the eyeball and protect it from injury. Their shape is such that the eyeball is completely covered when they are closed. Strong mechanical, optical, and acoustic stimuli (such as a foreign body, blinding light, or sudden loud noise) “automatically” elicit an eye closing reflex. The cornea is also protected by an additional upward movement of the eyeball (Bell’s phenomenon). Regular blinking (20–30 times a minute) helps to uniformly distribute glandular secretions and tears over the conjunctiva and cornea, keeping them from drying out.

Structure of the eyelids: The eyelids consist of superficial and deep layers (Fig. 2.1).

Superficial layer:

–Thin, well vascularized layer of skin.

–Sweat glands.

–Modified sweat gland and sebaceous glands (ciliary glands or glands of Moll) and sebaceous glands (glands of Zeis) in the vicinity of the eyelashes.

–Striated muscle fibers of the orbicularis oculi muscle that actively closes the eye (supplied by the facial nerve).

Deep layer:

–The tarsal plate gives the eyelid firmness and shape.

–Smooth musculature of the levator palpebrae that inserts into the tarsal plate (tarsal muscle). The tarsal muscle is supplied by the sympathetic nervous system and regulates the width of the palpebral fissure. High sympathetic tone contracts the tarsal muscle and widens the palpebral fissure; low sympathetic tone relaxes the tarsal muscle and narrows the palpebral fissure.

–The palpebral conjunctiva is firmly attached to the tarsal plate. It forms an articular layer for the eyeball. Every time the eye blinks, it acts like a windshield wiper and uniformly distributes glandular secretions and tears over the conjunctiva and cornea.

18 2 The Eyelids

Sagittal section through the upper eyelid.

Fig. 2.1 The superficial layer of the eyelid consists of the skin, glands of Moll and Zeis, and the orbicularis oculi and levator palpebrae muscles. The deep layer consists of the tarsal plate, tarsal muscle, palpebral conjunctiva, and meibomian glands.

–Sebaceous glands (tarsal or meibomian glands), tubular structures in the cartilage of the eyelid, which lubricate the margin of the eyelid. Their function is to prevent the escape of tear fluid past the margins of the eyelids. The fibers of Riolan’s muscle at the inferior aspect of these sebaceous glands squeeze out the ducts of the tarsal glands every time the eye blinks.

angular eyelid defect with its base at the margin of the eyelid results from a reduction malformation during closure of the optic cup in the embryonic stage.

Treatment: Defects are closed by direct approximation or plastic surgery with a skin flap.

2.3.2Epicanthal Folds

A crescentic fold of skin usually extending bilaterally between the upper and lower eyelids and covering the medial angle of the eye. This rare congenital anomaly is harmless and typical in eastern Asians. However, it also occurs with Down’s syndrome (trisomy 21 syndrome). Thirty per cent of newborns have epicanthal folds until the age of six months. Where one fold is more pronounced, it can simulate esotropia. The nasal bridge becomes more pronounced as the child grows, and most epicanthal folds disappear by the age of four.

2.3.3Blepharophimosis

This refers to shortening of the horizontal palpebral fissure without pathologic changes in the eyelids. The palpebral fissure, normally 28–30 mm wide, may be reduced to half that width. Blepharophimosis is a rare disorder that is either congenital or acquired (for example, from scar contracture or aging). As long as the center of the pupil remains unobstructed despite the decreased size of the palpebral fissure, surgical enlargement of the palpebral fissure (by canthotomy or plastic surgery) has a purely cosmetic purpose.

22 2 The Eyelids

2.3.4Ankyloblepharon

This refers to horizontal shortening of the palpebral fissure with fusion of the eyelids at the lateral and medial angles of the eye. Usually, the partial or total fusion between the upper and lower eyelids will be bilateral, and the palpebral fissure will be partially or completely occluded as a result. Posterior to the eyelids, the eyeball itself will be deformed or totally absent. Ankyloblepharon is frequently associated with other skull deformities.

2.4Deformities

2.4.1Ptosis

Definition

Paralysis of the levator palpebrae muscle with resulting drooping of one or both upper eyelids (from the Greek ptosis, a falling). The following forms are differentiated according to their origin (see also Etiology):

Congenital ptosis (Fig. 2.4).

Acquired ptosis:

–Paralytic ptosis.

–Sympathetic ptosis.

–Myotonic ptosis.

–Traumatic ptosis.

Epidemiology. On the whole ptosis is a rare disorder.

Etiology: Ptosis may be congenital or acquired.

Congenital ptosis.

Fig. 2.4 Congenital ptosis of the levator palpebrae muscle causes the upper eyelid to droop; usually the deformity is unilateral. Amblyopia will result if the center of the pupil is covered.