Untitled Flashcards Set

DISORDERS THAT INTERFERE WITH VISION REFRACTIVE ERRORS REFRACTIVE ERRORS HYPEROPIA/FARSIGHTEDNESS • vision is blurry at a close range and clear at a far • normal hyperopia of preschoolers needs no children of this age because at about 5 years of age, as a result of developmental changes, hyperopia will begin to diminish. • Focusing on close objects requires such strong accommodation that these children often develop headaches or dizziness while doing schoolwork. MANAGEMENT • A finding of hyperopia in a school-age child is cause for referral so that the child can get a prescription for glasses with a convex lens. MYOPIA/NEARSIGHTEDNESS • occurs when light rays focus anterior to the retina, causing objects that are far away to be unfocused. • Typically, this develops around age 8 years and ASSESSMENT • These children can read a book or a computer screen immediately in front of them but are unable to read the blackboard clearly from a distance. • They have difficulty reading signs across the street or playing baseball. Myopia tends to plateau as the child reaches adolescence. Children with myopia need corrective (concave) lenses to enable them to see at a distance LASER IN SITU KERATOMILEUSIS (LASIK) and PHOTOREFRACTIVE KERATECTOMY (PRK) • permanently change the contour of the cornea and correct refractive vision errors • both laser surgery correction procedures for either myopia or hyperopia •involve an incision under the cornea to change the contour of the eye globe so that light rays fall more accurately on the retina MANAGEMENT AFTER SURGERY •Postoperatively, children may have disturbed tear functioning for 1 or more months and so need to instill artificial tears or ointments to prevent surface damage. • having the procedure carried out before the child's eye globe has reached its adult size would require the surgery to be repeated with maturity, the youngest age at which LASIK therapy is appropriate is controversial; • most authorities recommend this not be done before 21 years of age to allow for natural eye contour changes to occur. •The exception to this is children who have amblyopia or strabismus ASTIGMATISM • an irregular curvature of the cornea, causing light to focus incorrectly on the retina, resulting in an uneven quality of vision. ASSESSMENT • When children with astigmatism look at the letter T, for example, they may see the crossbar but not the letter stem. • If they focus on the stem, they cannot see the crossbar. • On any given page of print, therefore, they may see only half the letters or can have great difficulty reading or following written instructions. • They may report headache and vertigo after doing close work. • Even though their vision appears deceptively normal on vision screening tests (they are able to see all of the numbers on a chart by tilting their head), these children need to be referred to an ophthalmologist on the basis of their other problems such as vertigo, headaches, and difficulty with reading. MANAGEMENT • Corrective lenses for close work relieve the symptoms and restore functional vision. • Contact lenses may be even more helpful because they actually smooth out the curvature of the cornea. • A form of LASIK surgery may be appropriate to correct astigmatism. NYSTAGMUS • rapid, irregular eye movement, either vertically or horizontally. • It is not a disease in itself but rather a symptom of an underlying disease condition. • It is seen in children with vision-impairing lesions such as congenital cataracts. • It also occurs as a neurologic sign if there is a lesion of the cerebellum or brain stem. MANAGEMENT • Children with nystagmus should be referred to their primary care provider initially so the underlying cause of the symptom can be determined. • A referral to an ophthalmologist may be indicated. AMBLYOPIA • "lazy eye" or subnormal vision in one eye that causes a child to use only one eye for vision while "resting" the other eye can also develop from strabismus (crossed eyes). With strabismus, one eye looks straight ahead while the other eye "wanders," causing suppression of one visual image or a loss of central vision in that eye (amblyopia). • The same phenomenon can occur if the vision in one eye is obscured by a lid that does not open fully (ptosis). ASSESSMENT It is recommended that all children between the ages of 3 and 5 years have at least one vision screening to detect amblyopia • If a child has amblyopia, a screening exam such as a preschool E chart typically demonstrates 20/50 vision (which is normal for preschool age) in one eye, but the other eye shows lessened vision (perhaps as different as 20/100). MANAGEMENT • Treatment for amblyopia is most successful among children younger than the age of 7 years, but there is evidence to show a response to treatment for children between 7 and 13 years of age • Treatment can consist of wearing correcting lenses (glasses), covering the good eye with a patch, or a combination of the two •Wearing a patch over the good eye forces the child to use the poor eye, thus developing vision in that eye. •Usually, children have some difficulty initially adjusting to a patch because they are unable to see well from the unpatched eye. •They may report headaches or dizziness and notice poor depth perception. • Only constant attempts to see with the weaker eye, however, will improve binocular vision, so parents have to enforce patching if prescribed • The patch should be removed for 1 hour each day to prevent amblyopia from developing in the nonamblyopic eye. • If patching does not produce the anticipated result, LASIK surgery to improve the refractive error may be indicated. • Yet, a further option is the administration of levodopa in addition to occlusion therapy because this almost immediately improves vision in both eyes COLOR VISION DEFICIT (COLOR BLINDNESS) • the name implies, the inability to perceive color correctly. •It occurs in 4% to 8% of boys because one of the sets of cones of the retina that perceive red, green, or blue is absent. • It is inherited as a sex-linked disorder, although there is also a high incidence in children with hemophilia (which is also sex linked), congenital nystagmus, or glucose-6-phosphate dehydrogenase deficiency. ASSESSMENT • The vision problem may involve the inability to distinguish red from green or blue from yellow. • A small proportion of children are unable to see any colors. • It can be detected by the use of color plates or discs for children as young as preschool age. • Children with normal vision see numbers or patterns on these plates, whereas children with a color vision deficit see only a jumble of dots or unclear images. MANAGEMENT • There is currently no therapy for color vision deficit because the condition is caused by a genetic mutation. •The deficit is categorized based on severity. •It's important that the loss of color perception is detected early so the child is not asked to complete color identification assignments in preschool and can learn to appreciate color changes in traffic signals or other color-dependent signs necessary for safety. • Some children associate color blindness with total "blindness" and fear they will eventually lose their eyesight • Reassure them that although color blindness means they have a loss of color discrimination their loss is limited to that one area.