Where does a visual impairment begin? Vision disorders can be influenced by a combination of genetic factors, environmental conditions, and lifestyle choices. When taking these into account, beginning with proper prenatal care is a good place to start.
Where does a visual impairment begin? Vision disorders can be influenced by a combination of genetic factors, environmental conditions, and lifestyle choices. When taking these into account, beginning with proper prenatal care is a good place to start. Although some disorders cannot be cured, complications and symptoms, including pregnancy complications, can be reduced.
The more premature a delivery, low birth weight, and other health factors increase the risk of possible visual complications to include retinopathy of prematurity (ROP), a disruption of eye development; intraventricular hemorrhage (IVH), blood vessels within brain that burst and bleed into hollow chambers normally reserved for cerebrospinal fluid and into the surrounding tissues; hydrocephalus, an abnormal increase in the amount of cerebrospinal fluid within the cranial cavity causing enlargement of the skull and forehead; and neonatal infections, to name a few.
Treatment includes the use of lung surfactants to reduce the risk of respiratory distress, blood transfusions to improve blood pressure and blood count, spinal tap to drain fluid, and/or placement of a ventriculoperitoneal (VP) shunt to drain fluid from the brain.
With ROP, eye development can be disrupted, and normal vessels may stop growing or begin to grow abnormally from the retina. These vessels are fragile and can leak, and scar tissue may develop and pull the retina away from the inner surface of the eye. Severe symptoms of ROP include abnormal eye movement, crossed eyes, severe nearsightedness, or white-looking pupils (leukocoria).
Severe cases of ROP include plus disease, which is a major complicating factor at any stage. This is characterized by vascular dilation and tortuosity of the blood vessels that may lead to total retinal detachment, vitreous and anterior chamber haze, iris vascular engorgement, and immature blood vessels growing over the lens, restricting pupil dilation, although these symptoms usually appear later in development. Patients with severe cases of ROP are at greater risk for developing strabismus, cataracts, glaucoma, and becoming more highly myopic. Early detection or treatment can help prevent vision loss later in life.
Stages I to II of ROP usually improve with no treatment, and the disease resolves on its own without further progression and could eventually develop into normal vision.
Treatment for stages III and up for ROP include laser therapy, intravitreal injections (such as Avastin [Bevacizumab, Genentech]), which are usually reserved for very aggressive cases, cryotherapy, and, for more severe cases (stages IV and V), scleral buckle and/or vitrectomy.
Today, with higher survival rate of smaller and more premature infants, cases of ROP have increased, but with thorough eye examinations, early treatment can improve a baby’s chances for normal vision.
Other risk factors for vision disorders include: cerebral palsy, albinism, epilepsy, autism, and developmental disabilities. Neurological disorders, such as traumatic brain injury or cortical visual impairment, can also affect vision due to trauma of the brain, not the eyes. The degree of impairment depends on onset, location, and intensity; it can range from severe impairment to blindness. Asphyxia (lack of oxygen to the brain), hypoxia (lack of oxygen in the body cells, tissue, or blood) and ischemia (not enough blood supply to the brain) can also cause brain defects and permanent vision loss.
Children with visual impairments can show symptoms that might mimic others, such as “blindism” (self-stimulatory behavior, rituals), which is often mistaken for autism, and children with neurological vulnerabilities (e.g., seizure disorders, prematurity associated with bleeds, agenesis of the corpus callosum, etc.) may be at increased risk. These similarities can often result in misdiagnosis.
Other visual impairment such as nystagmus (rapid involuntary eye movement, usually side to side) can be sensory and can develop as a result of poor vision. Nystagmus can also develop as a result of a neurological problem, and nystagmic patients may experience problems with depth perception. Sudden onset of nystagmus may be a sign of a serious medical condition, including severe head trauma, toxicity, stroke, inflammatory disease, or other conditions that affect the brain. Immediate medical attention is necessary.
Some common causes of visual impairment include significant refractive error (excessive or unequal myopia, hyperopia, and astigmatism), strabismus, amblyopia, and binocular visual impairment. A comprehensive eye exam is recommended at six months of age to ensure the eyes perform as a team and there is normal eye development. Amblyopia and strabismus are most effectively treated when detected early. Eye examinations can also detect systemic diseases such as high blood pressure and diabetes.
It is important to understand vision problems and symptoms. A head tilt might indicate double vision; excessive tearing and red or encrusted eyelids may indicate blocked tear ducts or infection. Pupil defects could be a sign of eye cancer, nerve damage, tumor, or defect inside the eye; and an eye turn may be a sign of poor muscle control. Many eye diseases have no early symptoms, and you may see no change in the patient’s vision until the disease has become advanced. The single best way to protect vision is through regular eye examinations.
Most children who are visually impaired have low vision. They use their vision for learning along with tactile and auditory adaptations. This may include increased contrast and color highlighting, lighting enhancement, and reading standard print with the use of hand-held or stand magnifiers that can be used for near tasks or enlarged print. Technological equipment such as closed circuit televisions (CCTVs) or screen enlargement programs for computers can be used as well as monoculars and telescopes for distance viewing. As technology is improving, many visually impaired children rely on auditory information for some part of their learning. Books on CD, spoken output from the computer, and use of tape recorders for memos provide quick means of access.
Children who are blind will depend on tactile and auditory methods for learning. They may use Braille, tactile material such as raised maps, speech access, and auditory descriptions. Braille can be written and read using portable note-takers with Braille displays or computer output. Children who have been blind since birth might find it difficult to understand verbal descriptions; therefore, direct contact with materials or objects is beneficial because they cannot gain this information through pictures.
Children with visual impairments may also benefit from orientation and mobility instruction, independent living skills, career development, use of assistive technology, use of functional vision, and communication and social skills. It is also important to experience some type of routine physical activity program to improve fitness and provide confidence. It can also develop motor skills needed for daily living and mobility tasks.
Although vision loss can result from disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction or medications, preventive eye care is the first line of defense against vision problems. Regular eye exams with an eyecare professional and annual physical exams may offer more treatment options to provide a better visual outcome in the future.