Refractive errors cause decreased vision, visual discomfort ("eye strain"), and/or amblyopia. The most common form, nearsightedness (poor distance vision) is usually seen in school-age children and is treated effectively, in most cases, with glasses. Farsightedness can cause problems with focusing at near and may be treated with glasses. Astigmatism (imperfect curvature of the front surfaces of the eye) also requires corrective lenses if it produces blurred vision or discomfort. Uncorrected refractive errors can cause amblyopia particularly if they are severe or are different between the two eyes.
In addition to detection of vision problems, effective screening programs should also place emphasis on a mechanism to inform parents of screening failures and attempt to ensure that proper follow-up care is received.
What is Amblyopia?
Amblyopia is poor vision in an otherwise normal appearing eye, which occurs when the brain does not recognize the sight from that eye. Two common causes are strabismus (misaligned eyes) and a difference in the refractive error (need for glasses) between the two eyes. If untreated, amblyopia can cause irreversible visual loss. The best time for treatment is in the preschool years. Improvement of vision after the child is 8 or 9 years of age is rare.
What is Strabismus?
Strabismus is misalignment of the eyes in any direction. Amblyopia may develop when the eyes do not align. If early detection of amblyopia secondary to strabismus is followed by effective treatment, then excellent vision may be restored. The eyes can be aligned in some cases with glasses and in others with surgery. However, restoration of good alignment does not assure elimination of amblyopia, and continued care after restoration of good alignment is essential.
The physicians at EyeHealth Northwest recommend an ophthalmological examination be performed whenever questions arise about the health of the visual system of a child of any age. They recommend that infants and children be screened for vision problems as follows and any child who does not pass these screening tests have an ophthalmological examination.
- A pediatrician, family physician, nurse practitioner, or physician assistant should examine a newborn's eyes for general eye health including a red reflex test in the nursery. An ophthalmologist should be asked to examine all high risk infants, i.e., those at risk to develop retinopathy of prematurity (ROP), those with a family history of retinoblastoma, glaucoma, or cataracts in childhood, retinal dystrophy/degeneration or systemic diseases associated with eye problems, or when any opacity of the ocular media or nystagmus (purposeless rhythmic movement of the eyes) is seen. Infants with neuro-developmental delay should also be examined by an ophthalmologist.
- All infants by six months to one year of age should be screened for ocular health including a red reflex test by a properly trained health care provider such as an ophthalmologist, pediatrician, family physician, nurse, or physician assistant during routine well-baby follow-up visits.
- Vision screening should also be performed between 3 and 3 1/2 years of age. Vision and alignment should be assessed by a pediatrician, family practitioner, ophthalmologist, optometrist, orthoptist, or individual trained in vision assessment of preschool children. Emphasis should be placed on checking visual acuity as soon as a child is cooperative enough to complete the examination. Generally, this occurs between ages 2 ½ to 3 ½. It is essential that a formal testing of visual acuity be performed by the age of 5 years.
- Some evidence currently exists to suggest that photoscreening may be a valuable adjunct to the traditional screening process, particularly in pre-literate children.
- Further screening examinations should be done at routine school checks or after the appearance of symptoms.
- School aged children who pass standard vision screening tests but who demonstrate difficulties learning to read, should be referred to reading specialists such as educational psychologists for evaluation for language processing disorders such as dyslexia. There is not adequate scientific evidence to suggest that "defective eye teaming", and "accommodative disorders" are common causes of educational impairment. Hence, routine eye screening for these conditions is not recommended.