Ординатура / Офтальмология / Английские материалы / Handbook of Pediatric Neuro-Ophthalmology_Wright, Spiegel, Thompson_2006

Munsell 100 hue test or the Farnsworth D-15 test2; these involve arranging colored caps between pairs of reference caps that are placed at each end of a long narrow rectangular box. Characteristic patterns of confusion are seen in individuals with congenital and acquired color vision defects. This test requires a fair amount of cognitive ability, and children usually must be 6 or 7 years of age before such testing is possible.

FUNDUSCOPIC EXAM

The funduscopic exam is crucial in the evaluation of children with neuro-ophthalmic disorders, because most cases of visual loss or nystagmus are caused by an optic nerve or macular disorder that can usually be diagnosed with indirect ophthalmoscopy (Table 2-7). The test can be done by having the child cradled in the parent’s lap, with the child’s feet tucked under the parent’s elbows, and the head supported by the parent’s closed knees. If possible, to facilitate cooperation, keep the infant slightly hungry and feed the bottle during the fundus exam. If the child does provide some resistance, an assistant can be used to stabilize the head. The use of a lid speculum may be necessary, but every effort should be made to avoid it. Parents do not like the lid speculum and may become quite annoyed with the physician’s “barbaric” techniques. Attempts at reassuring the parents that this is not uncomfortable, when the child is screaming loudly, usually are unsuccessful.

The older infant and young child can be persuaded into cooperating for the indirect ophthalmoscopy exam by making some

TABLE 2-7. Possible Etiology of Decreased Vision.

FIGURE 2-11. Indirect ophthalmoscopy in a child can be performed by using a 20 diopter lens. Control and stability can be obtained by resting the fingers on the child’s forehead.

compromises in the quality of the exam. The first is to use as low illumination as possible. Although this does decrease the quality of the image, it is much better to get a “grade B” look of the fundus rather than a “grade A” view of the closed lids or inferior sclera. Second, avoid manipulating the lids as this usually causes the child to squeeze and results in the Bell’s phenomena. By using a 20 diopter indirect lens and resting the fingers lightly on the child’s forehead for support, the examiner can get an excellent view of optic nerve and macula (Fig. 2-11). Last, quick views should be obtained of each eye before prolonged retinal or optic nerve examination is attempted as all too often the child rapidly becomes uncooperative. A quick view of each eye is better than none at all. The peripheral fundus is rarely of neuro-ophthalmic significance but can be examined with a 28 diopter indirect lens if necessary.

GENERAL NEUROLOGICAL EVALUATION

The ocular findings must be evaluated in the context of the patient’s overall neurological condition to reach a valid conclusion. In searching for associated neurological abnormalities, questions should be asked about such entities as seizures, ataxia, decreased hearing, and spasticity. In young infants, much can be learned by assessing general neurodevelopment as this will

give some indication of neurological impairment. The best milestones to check are those which mothers tend to remember clearly (smiling, sitting, standing, walking, first words, feeding self, and bladder control), and the experienced mother should be asked to make comparisons with her other children. Discrepancies may have diagnostic value, because delay in a single area nearly always indicates a localized rather than a generalized defect.15 Table 2-8 is a summary of some of the more common neurological milestones and their time of occurrence.

A detailed neurological examination in a child is beyond the expertise of most ophthalmologists, but a few areas are of particular concern. Helpful neuro-ophthalmic localizing information can be learned by assessing the trigeminal nerve (facial sensation), facial nerve (muscles of facial expression), and the auditory nerve (hearing). As an example, an abduction deficit plus ipsilateral facial weakness is most likely caused by a lesion in the brainstem (pons). An abduction weakness plus ipsilateral hearing loss and facial pain is most likely the result of inflammation of the petrous bone (Gradenigo’s syndrome). Testing motor function and sensation in the upper and lower extremities, although less helpful from an ophthalmic standpoint, should also be attempted. Such information can be useful in guiding further neurological and neuroradiologic investigation. Only by considering the ocular abnormality within the context of the entire neurological system can appropriate therapy be recommended.

TABLE 2-8. Developmental Milestones in Infants and Children.

Data from Gesell and Amatruda. Developmental diagnosis. New York: Harper & Row, 1974; Illingworth. The development of the infant and young child: normal and abnormal. New York: Churchill Livingstone, 1980; Farmer TW (ed) Pediatric neurology. Philadelphia: Harper & Row, 1983, with permission.

References

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affect a child’s emotional, neurological, and physical development by potentially limiting the range of experiences and the kinds of information to which a child is exposed.

CLINICAL FEATURES

Decreased vision in a child can be caused by many different processes, each one requiring a different method of treatment: either medical, surgical, or optical. If normal vision cannot be restored, then the use of both optical and nonoptical aids to enhance the remaining vision is necessary.

Whatever the cause of the decreased vision, early intervention is of the utmost importance for the child to adapt to the environment and to continue the learning processes without interruption. The clinical features that could alert a parent to signs of a visual problem in their child include, but are not limited to, nystagmus, strabismus, random eye movements, leukocoria, and corneal opacity.

CLINICAL ASSESSMENT

Clinical assessment of a child with a suspected visual impairment always consists of a very detailed clinical evaluation by a pediatric ophthalmologist, with ancillary testing such as electrophysiology and ultrasonography when appropriate.

The measurement of visual function should be done with targets appropriately sized for both the age of the child and the level of vision suspected, moving the child closer to the testing targets both for near and for distance. The visual requirements for each child should also be assessed because the various therapeutic modalities are age and task appropriate.

The importance of early diagnosis of the child’s visual disability cannot be overstated. The earlier the disability is diagnosed, the earlier treatment intervention can begin. Early treatment may produce a better outcome by allowing a stepwise approach to planning the use of aids, both visual and nonvisual, for the short and long term. For those children with an inherited process, early diagnosis makes it possible to provide expedient and appropriate counseling for the families involved. Innumerable low-vision aids of various types are available for enhancing both distance and near vision. The type of device that

them highly portable. A child can use this device anywhere and can share it with normally sighted friends, thus erasing the stigma associated with the use of a low-vision aid.

The social and academic success of a child with a visual disability depends largely on the expectations of the family and the understanding of the teachers and the school administrators; the focus should not be on the limitations that the visual disability creates but on the heights that these children can achieve. Teachers, classroom aides, and playground supervisors should be encouraged to treat these children no differently than they treat the others in the class. However, staff need to remain aware of the children’s special needs and address these needs appropriately. Where these children are seated in the classroom, the distance between them and the blackboard, the size of the letters on the board, the color of the chalk used, and the angle of the glare from the windows are all as important as any optical or nonoptical visual aid being used.

Furnishing the family and the teachers with a detailed report of the size of print that the child can see for both near and distance work is most helpful. When there are problems with contrast on homework assignments (some copies are so poor that enlarging the print makes them impossible to read), a different type of copy for these children is important. For some children, a closed-circuit television (Fig. 3-3) facilitates reading when increased magnification is required, as the magnifying glass of increased power decreases the field of view. These devices are expensive, but an older child will find them very useful. Most schools with resource centers make them available, as do public libraries.

With increased awareness of and attention to those things that make schoolwork easier to handle, most children will adapt well to their less-than-normal vision, which will do more for their self-confidence than any expensive magnifier or complicated reading machine can possibly do. However, as the child becomes older and reading demands increase, these more sophisticated instruments will become appropriate and should be added to the armamentarium. Newer instruments include closed-circuit television cameras that can be used with computers and portable handheld devices that scan curved surfaces and have large-print readouts on the handles. There are many headborne devices, used for both distance and near reading, that are appropriate for adults who need them to maintain a career. These newer devices are not really necessary in the elementary

FIGURE 3-3. Closed-circuit television.

and high school classroom, but they may be more useful to college students who sit in large classrooms and who may find it necessary to copy notes from distant blackboards or screens.

There are some points to remember when evaluating a child for visual aids:

•Amblyopia can occur in the presence of another visual abnormality and should be treated vigorously. The better the vision, the less magnifying power needed.

•It is acceptable for moderate to high myopes to remove their glasses for near work.

•The accommodative range will decrease as these children get older, and a change in vision does not necessarily mean a worsening of a previously stable condition.

•There is no limit to the amount of reading aid that can be prescribed so long as this aid improves near vision.

•Only those visual aids that are needed for the currently performed tasks should be prescribed. For the young child, this will probably mean a stand magnifier for near tasks and a telescope for distance tasks.