CHAPTER 30 ■ EYE: VISUAL DISTURBANCES KAREN E DULL INTRODUCTION Sudden loss or deterioration of vision (or diplopia) can be caused by numerous diseases and injuries ( Tables 30.1 to 30.3 ) A systematic approach is necessary to reach a correct diagnosis and to minimize the risk of permanent visual impairment The patient’s age, underlying disease conditions, visual history, and history of possible injury must be determined The extent of the visual impairment, the rapidity of its onset, and the association with other systemic findings are vital pieces of information It is important to remember that visual acuity improves with age in children The normal visual acuity for a toddler is 20/40 and gradually improves to the normal adult acuity of 20/20 by age or years A careful eye examination, including gross and ophthalmoscopic examination, determination of extraocular movement, and visual acuity, together with the history, leads to correct diagnosis and management of the patient Few ocular conditions in the pediatric population are truly emergent ( Table 30.4 ), but many are urgent; most can be treated by the emergency physician or can be referred for appropriate follow-up with an ophthalmologist Many conditions seen by a pediatric ophthalmologist are not discussed here because they rarely are seen in the emergency department (ED) Conditions that are more likely to be seen in the ED are emphasized in this chapter PATHOPHYSIOLOGY Vision may be impaired through interference at any point in the visual pathway Light must reach the eye, pass through the cornea and the anterior chamber, be focused by the lens, pass through the posterior chamber, and reach the retina The retina must react to the visual stimuli, generate electrical impulses, and transmit these impulses along the optic nerve and eventually to the visual cortex for interpretation In addition, for binocular vision, the movement of both eyes must be coordinated and smooth Loss of clarity of the visual media or damage to the conductive tissues anywhere along the visual pathway can lead to decreased vision DIFFERENTIAL DIAGNOSIS Trauma and infections are the two most common causes of acute visual impairment that can interfere with any part of the visual pathway ( Tables 30.1