HESI TIPS PEDS HELP

HESI TIPS PEDS HELP Review Materials from Exam: PN Pediatrics 2 Assessment of Vision Major Developmental Characteristics of Vision Birth • Visual acuity 20/100 to 20/400* • Pupillary and corneal (blink) reflexes present • Able to fixate on moving object in range of 45 degrees when held 20 to 25 cm (8 to 10 inches) away • Cannot integrate head and eye movements well (doll's eye reflex—eyes lag behind if head is rotated to one side) 4 weeks of age • Can follow in range of 90 degrees • Can watch parent intently as he or she speaks to infant • Tear glands begin to function • Visual acuity is hyperoptic because of less spherical eyeball than in adult 6 to 12 weeks of age • Has peripheral vision to 180 degrees • Binocular vision begins at age 6 weeks, is well established by age 4 months • Convergence on near objects begins by age 6 weeks, is well developed by age 3 months • Doll's eye reflex disappears 12 to 20 weeks of age • Recognizes feeding bottle • Able to fixate on a 1.25-cm (0.5-inch) block • Looks at hand while sitting or lying on back • Able to accommodate to near objects 20 to 28 weeks of age • Adjusts posture to see an object • Able to rescue a dropped toy • Develops color preference for yellow and red • Able to discriminate among simple geometric forms • Prefers more complex visual stimuli • Develops hand-eye coordination 28 to 44 weeks of age • Can fixate on very small objects • Depth perception begins to develop. • Lack of binocular vision indicates strabismus. 44 to 52 weeks of age • Visual acuity 20/40 to 20/60 • Visual loss may develop if strabismus is present. • Can follow rapidly moving objects Clues for Detecting Visual Impairment Refractive Errors Myopia Nearsightedness—Ability to see objects clearly at close range but not at a distance Pathophysiology—Results from eyeball that is too long, causing image to fall in front of retina Clinical manifestations • Rubs eyes excessively • Tilts head or thrusts head forward • Has difficulty in reading or performing other close work • Holds books close to eyes • Writes or colors with head close to table • Clumsy; walks into objects • Blinks more than usual or is irritable when doing close work • Is unable to see objects clearly • Does poorly in school, especially in subjects that require demonstration, such as arithmetic • Dizziness • Headache • Nausea following close work Treatment—Corrected with biconcave lenses that focus image on retina Hyperopia Farsightedness—Ability to see objects at a distance but not at close range Pathophysiology—Results from eyeball that is too short, causing image to focus beyond retina Clinical manifestations • Because of accommodative ability, child can usually see objects at all ranges. • Most children normally hyperopic until about 7 years of age Treatment—If correction is required, use convex lenses to focus rays on retina. Astigmatism Unequal curvatures in refractive apparatus Pathophysiology—Results from unequal curvatures in cornea or lens that cause light rays to bend in different directions Clinical manifestations • Depend on severity of refractive error in each eye • May have clinical manifestations of myopia Treatment—Corrected with special lenses that compensate for refractive errors Anisometropia Different refractive strengths in each eye Pathophysiology—May develop amblyopia because weaker eye is used less Clinical manifestations • Depend on severity of refractive error in each eye • May have clinical manifestations of myopia Treatment—Treated with corrective lenses, preferably contact lenses, to improve vision in each eye so they work as a unit Amblyopia Lazy eye—Reduced visual acuity in one eye Pathophysiology • Condition results when one eye does not receive sufficient stimulation (e.g., from refractive errors, cataract, or strabismus). • Each retina receives different images, resulting in diplopia (double vision). • Brain accommodates by suppressing less intense image. • Visual cortex eventually does not respond to visual stimulation, with loss of vision in that eye. Clinical manifestation—Poor vision in affected eye Treatment—Preventable if treatment of primary visual defect, such as anisometropia or strabismus, begins before 6 years of age Strabismus “Squint” or cross-eye—Malalignment of eyes Esotropia—Inward deviation of eye Exotropia—Outward deviation of eye Pathophysiology • May result from muscle imbalance or paralysis, from poor vision, or as congenital defect. • Because visual axes are not parallel, brain receives two images and amblyopia can result. Clinical manifestations • Squints eyelids together or frowns • Has difficulty focusing from one distance to another • Inaccurate judgment in picking up objects • Unable to see print or moving objects clearly • Closes one eye to see • Tilts head to one side • If combined with refractive errors, may see any of the manifestations listed for refractive errors • Diplopia • Photophobia • Dizziness • Headache • Cross-eye Treatment • Depends on cause of strabismus • May involve occlusion therapy (patching stronger eye) or surgery to increase visual stimulation to weaker eye • Early diagnosis essential to prevent vision loss Cataracts Opacity of crystalline lens Pathophysiology—Prevents light rays from entering eye and being refracted on retina Clinical manifestations • Gradually less able to see objects clearly • May lose peripheral vision • Nystagmus (with complete blindness) • Gray opacities of lens • Strabismus • Absence of red reflex Treatment • Requires surgery to remove cloudy lens and replace lens (intraocular lens implant, removable contact lens, prescription glasses) • Must be treated early to prevent blindness from amblyopia Glaucoma Increased intraocular pressure Pathophysiology • Congenital type results from defective development of some component related to flow of aqueous humor. • Increased pressure on optic nerve causes eventual atrophy and blindness. Clinical manifestations • Mostly seen in acquired types; loses peripheral vision • May bump into objects not directly in front • Sees halos around objects • May complain of mild pain or discomfort (severe pain, nausea, vomiting, if sudden rise in pressure) • Redness • Excessive tearing (epiphora) • Photophobia • Spasmodic winking (blepharospasm) • Corneal haziness • Enlargement of eyeball (buphthalmos) Treatment • Requires surgical treatment (goniotomy) to open outflow tracts • May require more than one procedure Special Tests of Visual Acuity and Estimated Visual Acuity at Different Ages Test Description Birth 4 Months 1 Year Age of 20/20 Vision (months) Optokinetic nystagmus A striped drum is rotated or a striped tape is moved in front of infant's eyes. Presence of nystagmus indicates vision. Acuity is assessed by using progressively smaller stripes. 20/400 20/200 20/60 20-30 Forced-choice preferential looking* Either a homogeneous field or a striped field is presented to infant; an observer monitors the direction of the eyes during presentation of pattern. Acuity is assessed by using progressively smaller striped fields. 20/400 20/200 20/50 18-24 Visually evoked potentials Eyes are stimulated with bright light or pattern, and electrical activity to visual cortex is recorded through scalp electrodes. Acuity is assessed by using progressively smaller patterns. 20/100 to 20/200 20/80 20/40 6-12 Data from Hoyt CS, Nickel BL, Billson FA: Ophthalmological examination of the infant: Development aspects, Surv Ophthalmol 26(4):177-189, 1982. * One type of preferential looking test is the Teller Acuity Card Test, in which a set of rectangular cards containing different black-and-white patterns or grading is presented to the child as an observer looks through a central peephole in the card. The observer, who is hidden from view, observes the variety of visual cues, such as fixation, eye movements, head movements, or pointing. The finest grading the child is judged to be able to see is taken as the acuity estimate. The test is appropriate for children from birth to 24-36 months of age. (Teller DY and others: Assessment of visual acuity in infants and children: The acuity card procedure, Dev Med Child Neurol 28(6):779-789, 1986.) Snellen Screening* Preparation 1 Hang the Snellen chart (Figure 1-49) on a light-colored wall so that the 20- to 30-foot lines are at eye level when children 6 to 12 years old are tested in the standing position. 2 Secure the chart to the wall with double-stick tape on the back side of all four corners. If the chart must be reversed for use of the letter or E chart, secure it at the top and bottom with tacks. Make sure that the chart does not swing when in place. 3 The illumination intensity on the chart should be 10 to 30 foot-candles, without any glare from windows or light fixtures. The illumination should be checked with a light meter. 4 Mark an exact 20-foot distance from the chart. Mark the floor with a piece of tape or “footprints” positioned so that the heels touch the 20-foot line. FIGURE 1-49 Snellen chart. A, Letter (alphabet) chart. B, Symbol E chart. Procedure 1 Place the child at the 20-foot mark, with the heel edging the line if child is standing or with the back of the chair placed at the marker if the child is seated. 2 If the E chart is used, accustom the child to identifying which direction the legs of the E are pointing. Use a demonstration E card for this purpose. 3 Teach the child to use the occluder to cover one eye. Instruct child to keep both eyes open during the test. Provide a clean cover card for each child, and discard after use. 4 If the child wears glasses, test only with glasses on. 5 Test both eyes together, then right eye, then left eye. 6 Begin with the 40- or 30-foot line, and proceed with test to include the 20-foot line. 7 With a child suspected to have low vision, begin with the 20-foot line and proceed until the child can no longer correctly read three out of four or four out of six symbols on a line. 8 Use covers on the Snellen chart to expose only one symbol or one line at a time. When screening kindergarten-age or older children, expose one line, but a pointer may be used to point to one symbol at a time. Recording and Referral 1 Record the last line the child read correctly (three out of four or four out of six symbols). 2 Record visual acuity as a fraction. The numerator represents the distance from the chart, and the denominator represents the last line read correctly. For example, 20/30 means that the child read the 30-foot line at a 20-foot distance. 3 Observe the child's eyes during testing, and record any evidence of squinting, head tilting, thrusting the head forward, excessive blinking, tearing, or redness. 4 Make referrals only after a second screening has been made on children who are potential candidates for referral. 5 The following children should be referred for a complete eye examination: a Three-year-old children with vision in either eye of 20/50 or less (inability to correctly identify one more than half the symbols on the 40-foot line) or a two-line difference in visual acuity between the eyes in the passing range; for example, 20/20 in one eye and 20/40 in the other b All other ages and grades with vision in either eye of 20/40 or less (inability to correctly identify one more than half the symbols on the 30-foot line) c All children who consistently show any of the signs of possible visual disturbances, regardless of visual acuity