Ординатура / Офтальмология / Английские материалы / Primary Care Ophthalmology_Palay, Krachmer_2005

Cavernous sinus disease (e.g., tumor, carotid-cavernous fistula)

Postviral syndrome in children (tumor must be excluded)

Idiopathic (the cause is not identified in some cases)

Differential Diagnosis

Conditions that may mimic a sixth cranial nerve palsy include the following:

•Thyroid eye disease

•Congenital esotropia

•Ocular myasthenia gravis

Workup

•Ophthalmologic evaluation is necessary for measurement of the deficit and evaluation for associated signs such as papilledema.

•Determination of the erythrocyte sedimentation rate is performed to address the possibility of giant cell arteritis in elderly patients.

•Neuroimaging (MRI with contrast) is indicated in patients without obvious vascular risk factors, progression of symptoms, or other cranial nerve involvement.

Treatment

•The underlying cause determines treatment.

•For transient cases, use of an alternating clip-on occluder can prevent diplopia.

•For long-term cases, the ophthalmologist may consider prisms, botulinum injection (of antagonist medial rectus), and eye muscle surgery.

Carotid Artery–Cavernous Sinus Fistula

Symptoms

•Unexplained, persistent redness of the eye often is the first symptom.

•Double vision is common.

•Pulsating intracranial noises may be reported.

Signs

•Dilated, tortuous conjunctival vessels usually are found (Fig. 12–15).

•Dysfunction of the third, fourth, or sixth cranial nerve may be identified.

•Proptosis is common.

•A cranial bruit may be auscultated by the physician.

•A dilated superior ophthalmic vein often is seen on neuroimaging.

•Intraocular pressure may be elevated.

Etiology

•The disorder originates from an abnormal communication between the highpressure arterial system and the low-pressure venous cavernous sinus.

224 CHAPTER 12 • Neuro-ophthalmology

FIGURE 12–15 Right eye of a 64-year-old woman who presented with redness, proptosis, and elevated intraocular pressure in that eye. Diplopia and pulsatile tinnitus also were described. Her examination revealed dilated, tortuous ocular vessels, with subsequent angiography demonstrating a carotid artery–cavernous sinus fistula.

•The disorder can be direct (high flow), between the internal carotid artery and the cavernous sinus (e.g., with trauma or rupture of intercavernous aneurysm), or indirect (low flow), originating from the smaller vessels of the external or internal carotid arteries (e.g., congenital, spontaneous).

Differential Diagnosis

Disorders that can be confused with a carotid-cavernous fistula include the following:

•Thyroid eye disease

•Orbital or cavernous sinus tumor

•Orbital inflammatory pseudotumor

•Other causes of a red eye

Workup

•MRI or CT imaging of the brain and orbits with contrast is indicated to evaluate the orbital anatomy. These studies often will demonstrate enlargement of the superior ophthalmic vein and other venous structures connecting to the cavernous sinus.

•Bilateral internal and external carotid angiography will display the source of the fistula, which often is multiple and/or bilateral and can be contralateral to signs, and will delineate involvement of other vessels in the brain (which can cause intracerebral hemorrhage).

Treatment

•Indirect fistulas may spontaneously remit, frequently after diagnostic angiography.

•Therapeutic interventional radiographic procedures (e.g., placement of intravascular coils) may be required.

Follow-up

•Ophthalmologic consultation is needed to follow potential ocular complications of glaucoma or central retinal vein occlusion.

•Cerebellar or brainstem disease

•Drugs and medications (e.g., alcohol, lithium, anticonvulsants)

•Blindness from any cause

Workup

•A careful drug history is needed.

•Evaluation by a neuro-ophthalmologist and/or an otolaryngologist is indicated.

•MRI of the brain with contrast frequently is helpful.

Treatment

• The underlying cause determines treatment.

230 CHAPTER 13 • Pediatric Ophthalmology

A B C

FIGURE 13–1 A, The normal eye, after developing full length, focuses on the retina without accommodation. B, An infant’s eye focuses behind the retina without accommodation. C, An infant’s eye focuses on the retina when the ciliary body contracts (arrows), relaxing the zonules and thickening the lens (accommodation).

At birth a normal term infant is hyperopic, or farsighted, because the eye is relatively short. This means that when the ciliary muscle, which changes the lens shape to focus images, is completely at rest, images are focused behind rather than on the retina, and the image is blurred. To clear the image, the infant eye focuses (accommodates) to pull the image forward onto the retina (Fig. 13–1). Infants and young children have strong ciliary muscles and can accommodate to see well at distance and near. Near work takes more accommodative effort than far work. As the child grows, the eyes grow, and as the eyes elongate, the hyperopia decreases. Most normal eye growth occurs before the age of 2 years, with slow growth thereafter to approximately 13 years.

Infants who are more farsighted than normal may have difficulty as they grow older and their accommodative capacities decrease. Usually the difficulty manifests between 2 and 4 years of age as the acute onset of in-turning of the eyes (esotropia). Symptoms also may occur with reading in late adolescence or early adulthood.

Children who are less hyperopic than normal (i.e., those with eyes longer than the norm) may become myopic, or nearsighted, as they grow. A symptomatic decrease in distance vision usually becomes manifest at approximately 9 to 11 years of age in girls and slightly later in boys. Once myopia begins, it usually increases slowly throughout puberty and the early adulthood years.

Approach to the Pediatric Eye Examination

Vision represents a complex interplay between static anatomic structures and dynamic neurologic and physiologic processes. When an infant is born, the eyes are anatomically formed, but vision is truly a developmental sense. Events affecting the visual system during the first weeks, months, and years of life determine how fully vision potential will be realized, with earlier events playing the most important roles. Primary care providers, parents, and pediatric ophthalmologists are the guardians of this potential, and in many infants, without the intervention of all parties, the full potential for vision is lost.

Premature Infants

Babies born at approximately 24 weeks of gestation may have partially fused eyelids—

aremnant of a normal developmental stage. The lids should open spontaneously over the ensuing weeks. Preterm infants born at less than 28 to 30 weeks of gestation have

amembrane over the pupil, representing vestiges of the tunica vasculosa lentis, an embryonic vascular network that covers the lens and is continuous with the border of the iris. Presence of the membrane dulls the red reflex, but the condition resolves spontaneously by 36 to 40 weeks of gestational age. If the membrane does not regress normally, persistent pupillary membranes and anterior polar cataracts may result (Fig. 13–2).

The dilator muscle of the pupil is not well developed for several months after term; therefore, pupils may be small (miotic) and the anterior chamber shallow. The corneal diameter should be approximately 9 to 10 mm.

For premature infants before they reach term gestational age, the most important eye evaluation is an examination with the indirect ophthalmoscope by an ophthalmologist to detect retinopathy of prematurity (ROP). Primary care providers examining preterm infants can, however, look for reaction to light demonstrated by the infant’s squeezing the eyes shut, a normal red reflex with direct ophthalmoscopy, and full spontaneous eye movements. An ophthalmologist should be involved in the care of all infants who weighed less than 1500 g at birth, were born at 32 weeks of gestational age or earlier, and selected infants with birthweights between 1500 and 2000 g with an unstable clinical course who may be at risk for ROP. The first ophthalmologic examination should be scheduled at 4 to 7 weeks after birth depending on gestational age at birth. The examination should take place at 31 weeks of postconceptional age or 4 weeks of post-natal age, whichever is later. Retinopathy of prematurity is the leading cause of pediatric blindness in the United States.

FIGURE 13–2 Failure of completion of any of the normal prenatal steps of ocular development results in congenital eye anomalies. Here, incomplete regression of tunica vasculosa lentis leaves a pupillary membrane and anterior lens plaque. Not all ocular anomalies are visually significant, but all children with such anomalies should be referred to an ophthalmologist for evaluation.

232 CHAPTER 13 • Pediatric Ophthalmology

Term to 4-Month-Old Infants

A screening eye examination generally is part of all well-baby checkups, but because the eye and vision change so rapidly throughout infancy and childhood, the focus and assessment of each examination also must change.

Because the macula is not fully developed until 3 to 4 months of age, the eyes do not fixate well centrally and do not “lock onto” and follow objects before this age; variable crossing or drifting out of the eyes may be observed.

To test children in this age range, the examiner should have the parent hold the infant in a feeding position with the baby looking at the parent’s face (Fig. 13–3). The parent then moves the head from side to side. The baby should grossly follow this movement with eyes or head and also should blink when a light is directed into the eyes.

Next, a gross inspection is made of the eyes and face. The lids, brows, and globes should look symmetrical. Any marked asymmetry is a warning signal, because the brain processes images from only one eye if the images from the two eyes are significantly different in any way.

Finally, the lights should be dimmed and the baby given a bottle, pacifier, or parent’s finger to suck. Suckling usually elicits opening of the eyes. Normal infants may even have lid retraction and reveal visible sclera above and below the cornea. While the infant’s eyes are open, the examiner uses a direct ophthalmoscope to look at the quality and symmetry of the red reflex. In blond or lightly pigmented infants, this reflex is truly orange-red. In more darkly pigmented infants, the reflex looks dull orange or whitish orange. This latter finding should not be confused with leukocoria, which is

FIGURE 13–3 The best stimulus for infant vision is a parent’s face. By 6 weeks of age the infant should look at the parent’s face and move eyes and head to follow as the parent changes position.