This article is from October 2006 and may contain outdated material.
Deficits in visual acuity or the visual system can turn the simplest activities of daily living into a challenge, and that is particularly true for people also living with neurologic, cognitive or developmental deficits.
The chances of encountering an intellectually impaired person in a clinical setting are quite high, with an estimated 7.5 million intellectually disabled people living in the United States and nearly 160 million more worldwide. Some estimates suggest that up to 75 percent of intellectually disabled individuals are also affected by some type of vision loss or abnormality. Moreover, ophthalmic impairments that are ordinarily associated with older patients in the general population tend to occur at an earlier age among individuals with intellectual disabilities.
Many Origins, Many Presentations
Anomalies and delays in brain development are typically sustained during gestation, childbirth or early childhood, although intellectual impairment can also result later in life secondary to traumatic brain injury, dementing illnesses or other neurological diseases. Among the most common developmental disorders are Down syndrome, fetal alcohol syndrome and fragile X syndrome. These patients may frequently present with refractive errors, astigmatism, strabismus, keratoconus, nystagmus, juvenile glaucoma or ocular malformations. The prevalence of cataracts has been reported to be much higher among the intellectually disabled than in the general population.
Communication, verbal and non. As in any clinical setting, communication between the physician and patient is essential for diagnosing problems and developing an effective treatment strategy. Patients with intellectual disabilities, however, are not always able to articulate their symptoms and concerns, which can be a baffling situation for a physician who has limited experience with this population. Consequently, the ophthalmologist may need to adapt clinical techniques to meet the needs of the patient. “You tailor the examination according to the capacity of that patient, to get what you need from them on that particular day, because it changes from day to day as well,” said Colin A. Scher, MD, director of pediatric ophthalmology at Children’s Specialists of San Diego, Rady Children’s Hospital.
Exams without words. Working with patients who have intellectual disabilities can be analogous to treating very young children who are not yet able to speak. “We work with preverbal children all the time,” noted Dr. Scher. “Our job is to use the appropriate exam procedure to get the data from the patient. Sometimes it’s using behavioral techniques like toys and finger puppets to check their motility and ability to focus. That alone will give us a lot of information. The same techniques can be used with a developmentally delayed older child or in a noncommunicating adult. You get very good data without compromising the exam. For example: Can the patient fix and follow? Is he able to track small objects? Are the eye movements full? Is each eye working as well as the other eye, or is one eye dominating? You can get all that information from a nonverbal patient.”
Visual Problem, or Neurologic?
Assessing vision in patients whose disability is acquired rather than congenital may call for extra care in the diagnosis. Patients with traumatic brain injury or dementing illness, for example, may suffer errors in processing information rather than true visual impairment.
“If someone has acquired cognitive impairment, it can be difficult to assess their vision. It’s a challenge if the patient can’t cooperate with the testing. It’s also hard to know how much of their test result is from their vision vs. how much is from the cognitive impairment,” said Andrew G. Lee, MD, professor of ophthalmology, neurology and neurosurgery at the University of Iowa.
Furthermore, he said, “There’s a lot of information about the testing of visual function in terms of acuity and visual field, but we really don’t have very good tests for assessing people’s processing speed and their functional abilities. For example, older patients with dementia. Their visual acuity and visual field might be perfectly normal, but they can’t process the information correctly.”
Long-term treatment. Given the obvious challenges with assessment, does diagnosis and treatment in patients with intellectual disabilities differ significantly from that of the general population? Not really. “We can use the same tests applicable to conventional patients in those who are intellectually challenged. Perhaps we would do MRI scanning earlier in someone who might be more difficult to evaluate,” said Dr. Scher. “Or, we might do an examination under anesthesia to look at the retina or optic nerve, if the patient is really uncooperative in the office, to get a better look at the anatomy. We might also follow these patients more closely because they may not be as proactive in complaining about problems with their vision.”
Loved ones at the ready. Quite possibly, though, the most integral part of managing patients with intellectual disabilities is family involvement and assistance with treatment. Monitoring the patient for developing eye problems, administering medication, patching eyes and other duties may be required of the caregivers.
“Educating the family about expectations, guiding them through the treatment process, and supporting them is very important. The family is a much bigger part of the treatment team in children with intellectual disabilities than in children who are otherwise developmentally within the norm,” Dr. Scher added.
Occasionally, despite the combined efforts of the ophthalmologist and family, treatment just isn’t successful. “Sometimes it’s impossible to get a patient to comply, especially one who is physically stronger and resistant to wearing a patch or glasses, for example,” said Dr. Scher. “If they make up their mind that they’re not going to do it, we might not get the results that we’d hoped for.”
For Screening and Following: Cast a Wide Net
With such a large population of intellectually disabled children and adults, it would seem probable that some individuals could get lost to vision screening. Fortunately, for the most part, this doesn’t seem to be the case.
“The system really works for this particular group because they usually get identified initially in childhood as having developmental issues. They get locked into screening systems quite early on, provided that there is compliance on the family’s side,” said Dr. Scher. “They’re usually examined on a regular basis, as one wants to detect the problem or the potential for a problem long before it’s actually emerged. Then, if something does emerge, we can address it and make sure their visual system reaches its full potential so that the other systems will also reach whatever potential they have.”
Eye care and all care. Dr. Lee agreed. “We try to use a multidisciplinary approach that combines low vision services, occupational and physical rehabilitation, and social services. So, many of our patients who have vision disturbances and brain disturbances that might delay or impair their cognitive development are seen in the Center for Disabilities and Development [at the University of Iowa]. We do what we can with the visual component, but the vision processing might be the limiting factor, rather than the actual transmission of the information. We identify patients with low vision who also have intellectual disabilities or processing difficulties. If they’re not in the system already, they’re identified through the eye clinic.” Referrals between these services are typical. “The patients sent from the rehabilitation clinic may be having problems with their rehabilitation. They want to maximize their low vision to ensure that vision is not the factor in the rehabilitation process,” Dr. Lee said.
According to Dr. Scher, developmentally challenged adults tend to receive care from pediatric ophthalmologists because these physicians are familiar with their level of intellectual functioning. He added, “I think that often ophthalmologists are not that comfortable seeing older patients with these conditions. They might feel insecure because they don’t see enough of these patients and they’re not sure how to manage them.”
To Help Them See Their World
In spite of the multiple challenges that intellectually disabled patients may present and the additional time necessary for thorough treatment, working with them to improve their vision and their ability to function in their environment can be extremely satisfying.
In considering his patients, Dr. Scher finds them “very emotionally and professionally rewarding. They are often very curious, and have a good sense of humor. They’re very direct with their comments and they respond wonderfully to being spoken to via respectful, normal conversation. They are a subset of patients who greatly benefit from being able to see clearly, to appreciate their world.”