Abstract
The purpose of this chapter is to provide the main indications, background, and procedures when assessing eye movement function in the pediatric patient. The assessment of extraocular motility function includes version and ductions using the H pattern test in order to determine the presence of underaction or overactions of the extraocular muscles (EOM). EOM testing detects abnormalities in the structural and neurological integrity caused by an acquired or congenital disease of the central nervous system. Deficits in eye movement function can also contribute to poor academic performance which requires a developmental approach to the assessment of saccadic and pursuit eye movements to determine if a referral for optometric vision therapy is indicated. For the older child who is reading to learn, an assessment of reading eye movements using objective tests, such as the Visagraph and/or the ReadAlyzer, will guide the direction of the management plan.
TopIntroduction
Eye movement testing in the pediatric population assesses a child’s visual system on several levels and should be evaluated during the primary care examination. First, the structural and neurological integrity is assessed to rule-out the presence of an acquired or congenital disease of the central nervous system requiring a neurological evaluation (London, 2020; Scheiman & Wick, 2020). Second, visual function and developmental status is assessed to determine the presence of learning related vision problems that may impact academic performance (Birnbaum, 1983; Maples, 2017; Rouse, 2006; Taub 2012).
There is a high prevalence of ocular motility function deficits in children with special needs (Taub, 2012). This can range from congenital or acquired strabismus due to cranial nerve palsies or due to delays in visual development. In addition, growing public health interest in sports-related concussions require clinicians to understand that ocular motility deficits are common visual sequela seen in particularly the adolescent population (Graham et al., 2014; Master et al., 2016; Galloway et al., 2017). Although poor reading ability is the main indication for testing in the pediatric population, some additional commonly reported vision symptoms associated with ocular motility deficits include:
- •
Loss of place, omission of words when reading.
- •
Poor efficiency with reading and other academic assignments resulting in poor reading comprehension.
- •
Difficulty fixating, locating, or tracking objects.
- •
Poor attention and easily distractible with sustained visual activities.
- •
Vague asthenopic symptoms around the head or eyes.
- •
Poor coordination of body and eyes.
- •
Vertigo, dizziness, motion sickness.
This chapter will be divided into two parts: Part I: Structural & Neurological Status and Part II: Visual Function and Developmental Status. Specific clinical procedures to accurately assess versional or conjugate ocular motility function in the pediatric patient will be presented.
Key Terms in this Chapter
Ductions: Monocular eye movements.
Pursuit: Slow, continuous, and conjugate (eyes moving in the same direction) eye movement used when the eyes follow an object that is moving slowly and smoothly.
Saccades: Rapid, step-like conjugate (eyes moving in the same direction) eye movements that redirects the line of sight from one position to another.
Latency: Refers to the time the eye movement (pursuit or saccade) response occurs after target motion.
Vergence Eye Movements: Are non-conjugate eye movements in which the eyes are moving in opposite directions. These movements involve either a convergence or divergence of the line of sight of each eye to fixate an object at near or in the distance.
Gain: Refers to the ratio of the eye velocity to the target velocity.
Versional Eye Movements: Are conjugate eye movements in which both eyes moving in the same direction. An example of versional eye movements is when both eyes are moving towards the right or the left at the same time.