Many children have difficulties with their vision even though they have passed their vision screening at the pediatrician's office or at school. Others struggle with their vision despite being told by an eye doctor that 'everything is fine, they see 20/20'. For many children, visual perceptual deficits go undiagnosed and untreated because they see 20/20.
Visual perception is a skill set used to gain information from the visual environment. There are several different aspects of visual perception that should develop normally as a child ages. These abilities are used by the child to learn from their environment. Visual perception is especially important at school as 80% or more of classroom learning occurs through the visual system. The aspects of visual perception include:
Visual Discrimination: This is the ability to determine the unique characteristics of similar forms and use those characteristics to determine “same” versus “different”. In reading, this skill is used to distinguish between words with similar beginnings or endings. In earlier life this is part of the foundation for matching and sorting.
Visual Memory: This is the visual perceptual ability to recall a visual form. This skill enables a child to recognize a shape, object, sight word or to recall what they have just read by processing the text through their working memory. Difficulties with visual memory will result in reduced reading comprehension.
Spatial Relations: This is the ability to identify differences among several similar objects. This skill allows children to understand relationships between objects and the underlying concepts of letter formation and math. In school, this skill is critical for reading, math, and science.
Form Constancy: This visual perceptual ability allows one to rotate or manipulate objects in the “mind's eye” and predict the result. This skill is important when determining differences in shape, size, and orientation. Deficiencies in form constancy may lead to letter reversals or difficulties with math, especially geometry.
Sequential Memory: This is the ability to recall a series of visual objects (letters, numbers, shapes) in the correct order. This skill is important for spelling accuracy and sight word recognition. Difficulties with sequential memory often contributes to poor spelling skills or sub-vocalization during writing or copying tasks.
Figure-Ground: This is the visual perceptual ability to identify a form within a crowded background. Children with poor figure-ground skills will often struggle as print becomes smaller and more crowded on a page. They will frequently lose their place while reading.
Visual Closure: This is the ability to visualize, or fill in missing information within an incomplete picture. This skill is important for spelling, reading comprehension, and reading fluency.
Collectively, we use these visual perceptual skills to make sense of our visual environment. Visual perceptual deficits, in turn, impedes one's ability to learn. Imagine if you could not tell subtle differences. A 'd' looks very similar to a 'b'. It would be difficult if seeing 'b' in a different font, at a different size, or in a different position in a word was an entirely new experience.
Fortunately, visual perceptual deficits can be identified and treated. The first step is to schedule an eye examination with a Residency-Trained Pediatric Optometrist. A Residency-Trained Pediatric Optometrist has received additional post-graduate training specific to pediatric eye care. These doctors have the training and knowledge necessary to properly examine children and identify visual perceptual deficits. The comprehensive eye examination will rule out visual input challenges, such as an uncorrected refractive error (prescription), amblyopia (lazy eye), strabismus (eye turn), accommodative dysfunction (eye focusing deficits), binocular vision dysfunction (eye teaming deficits) or oculomotor dysfunction (eye tracking deficits). Difficulties with visual input can make objects blurry, double or appear to move on the page. It is extremely difficult to interpret visual information without consistent visual input. For this reason, a comprehensive eye examination with a Residency-Trained Pediatric Optometrist should be performed prior to evaluating visual perceptual deficits.
Once age-appropriate visual input has been established, the doctor will then choose from a number of age-normalized tests to evaluate the child's visual perceptual skills. These tests compare a child to their peers in several areas of visual perception. If deficits are detected, a plan for treatment can be put in place to remediate the visual perceptual deficits.
It is also possible for visual perceptual deficits to be acquired later in life. This change typically is due to an event, such as a stroke or traumatic brain injury. Similar to the process in children, individuals who have experienced an acquired brain injury should be evaluated by an optometrist who is residency-trained in neuro-optometry. The doctor will be able to rule out the several vision conditions that can result from an acquired brain injury. Once the doctor has established stable visual input, they will evaluate the patient's visual perceptual abilities. A neuro-optometric vision rehabilitation program can then be prescribed to remediate the visual perceptual deficits.
If you suspect visual perceptual deficits in a family member, it is important that you begin by scheduling an eye examination with an optometrist with residency-training in pediatric optometry or neuro-optometry.