Notes compiled for Pediatrics. Ophthalmology. (Med I, Block 5, OP)

Transcription

1 Notes compiled for Pediatrics Ophthalmology (Med I, Block 5, OP)

2 Amblyopia and Strabismus University of Manitoba Faculty of Medicine MedII/OP7 Dr. P. Shuckett Objectives: 1. To state how to measure or estimate visual acuity in children 2. To detect strabismus by general inspection, the corneal light reflex test, and the cover test. 3. To explain why it is necessary to perform ophthalmoscopy in a child to rule out any organic causes of impaired vision when amblyopia is suspected. 4. To explain to parents the need for prompt treatment of amblyopia. This lecture is loosely based on the material found in Chapter 6,Basic Ophthalmology by Frank Berson Objectives include understanding the concepts of amblyopia and strabismus how they can be diagnosed, and a review of visual development and the measurement of vision in a child. ADULT (over 8) vs. CHILD ability to SUPPRESS DIPLOPLIA IN ADULTS The major difference between an adult and a child is the ability to suppress the information from one eye. The child suppresses the information from the non fixing eye. An adult can't and instead sees both images ie) double. EXTRAOCULAR MUSCLES -action, innervation MEDIAL RECTUS -adduction (3) LATERAL RECTUS -abduction (6) SUPERIOR RECTUS -elevation (3) INFERIOR RECTUS -depression (3) INFERIOR OBLIQUE-excyclorotation (3) SUPERIOR OBLIQUE incyclorotation (4) FUSION- TROPIA- PHORIA- ESO- EXO- HYPER- COMMITENT- NOMENCLATURE the brain's mechanism to keep the eyes working together preventing double vision and keeping them straight. a manifest turn, the fusion mechanism has broken down. a tendency for the eyes to turn. Fusion mechanism prevents this from occurring' If fusion is eliminated a turn develops eyes turned in eyes turned out one eye higher than the other the type of turn caused by fusional breakdown.not caused by a specific muscle weakness and therefore symmetrical. The type most commonly seen in children NONCOMMITENT- the type of turn caused by muscle palsx. Not symmetrical. Uncommon in children, STRABISMUS- turned eye i.e. one eye fixes on the object of regard; the other doesn't

3 Amblyopia and Strabismus University of Manitoba Faculty of Medicine Med II/OP 7 Dr. P. Shuckett DIAGNOSING STRABISMUS CORNEAL LIGHT REFLEX - does the light reflect in a symmetrical manner COVER TEST-diagnosing TROPIA Cover one eye observe the movement of the other v eye repeat covering the other eye movement=tropia UNCOVER TEST-diagnosing PHORIA cover test negative observe eye as you uncover it repeat for other eye movement=phoria ALTERNATE COVER TEST-diagnosing TROPIA or PHORIA cover one eye quickly cover the other movement=tropia or phoria VISUAL DEVELOPMENT-THEORETICAL BIRTH- 20/200- normal infants can see their mother 4 MONTHS- MACULA MATURE - baby can fix and follow with each eye. -if not refer 6 MONTHS- Evoked potential -fully developed 2 YEARS- 20/20 -using preferential looking. TESTING FOR ACUITY AND AMBLYOPIA FIXATION-after 4 months fix and follow (one eye at a time) FIXATION PREFERENCE up to 3 cover one eye and observe behavior PICTURE CARDS 3-4 differences more important - EGAME line difference or 20/40 -refer SNELLEN LETTERS 5+ 2 line difference or 20/40-refer

4 Amblyopia and Strabismus University of Manitoba Faculty of Medicine Med II/OP 7 Dr. P. Shuckett AMBLYOPIA-POTENTIALLY NORMAL VISION IN AN EYE WITH SUBNORMAL VISION. caused by visual deprivation or distortion reversed by "correcting cause " and forcing use of the amblyopic eye TOTAL DEPRIVATION OF ONE EYE FROM BIRTH-TWO MONTHS -IRREVERSIBLE 1 YEAR-1 MONTH TO REVERSE 6 YEARS -6 TO 12 MONTHS TO REVERSE 9 YEARS -NO REVERSAL *** RED REFLEX *** diagnose visual obstruction at birth TYPES OF STRABISMUS ESOTROPIA I NFANTILE (diagnosed by 6 months) Tx.-SURGERY ACCOMMODATIVE-accommodates because of hyperopia!eyes converge and fusion mechanism breaks down Tx.-SPECTACLES INCLUDING BIFOCALS THEN SURGERY (AMBLYOPIA COMMON) EXOTROPIA INTERMITTENT ~ AMBLYOPIA RARE Usually CONSERVATIVE MANAGEMENT

5 STRABISMUS and AMBLYOPIA Paul Shuckett Early diagnosis and treatment prevents visual loss Strabismus = misalignment of the eyes Amblyopia = visual impairment in one eye from lack of use A childs eye is not an adult eye Suppression Non-comitant Children do not outgrow crossed eyes 1

6 Eye Exercises do not correct learning disabilities Childs eye adult eye] Pseudostrabismus true strabismus Eye exercises do not work Strabismus suppression amblyopia loss of vision 2

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8 Diagnostic tests for strabismus Corneal Light Reflex Test Cover Tests Bruckner Test Cover test - tropia Uncover test -phoria Alternate cover test- tropia and phoria Tropia -one eye fixes on the object of regard. The other eye does not. Phoria -suppressed tendency for one eye to drift off the object of regard. Fusion keeps the eyes working together. When fusion is prevented (covering one eye) the covered drifts off the object of regard eye 4

9 Bruckner Reflex Direct ophthalmoscope 1 meter from patient Focus on cornea and compare red reflex Fail if difference in color or brightness Asymmetry represents strabismus or significant refractive diffference in the eyes 5

10 Diagnostic Tests for Amblyopia Measure Visual acuity Visual development Birth-visual acuity at least 20/200 Four Months- macula anatomically developed Eight years- entire eye and cortical systems fully mature 4-6 months 2-3 years 3-4 years 4-5 years follow toy flash cards illiterate E Snellen letters Infants Cover one eye at a time. Refer if Object when one eye is covered Following ability is unequal 6

11 Flashcards Teach objects binocularly Check vision one eye at a time Refer if: Discrepancy between the eyes Visual acuity <20/50 in either eye Illiterate E Teach child to use a hand held E Monocular testing Point to E s on chart Refer if Difference between eyes Vision 20/40 in either eye 7

12 Snellen Chart Teach child binocularly. If problems revert to E Monocular testing as in Illiterate E Refer if Difference of 2 lines Vision < 20/30 in a six year old Causes and Treatment of Amblyopia 8

13 Major causes of Amblyopia Strabismus-squint Anisometropia-difference in refractive error between the 2 eyes Vision deprivation of one eye Amblyopia Facts Total deprivation of one eye from birth to 3 months Best vision 20/200 Amblyopia discovered at age 1 Reversed in 1 month Amblyopia discoveed at age 3 Reversed in 3 months Amblyopia discovered age 6 Reversed in 6+ months 9

14 Referral for suspected amblyopia Decreased vision (one or both eyes) Strabismus Family history of strabismus or amblyopia Cataract, Glaucoma, other blocking mechanisms USE OPHTHALMOSCOPE TO EXAMINE Red reflex fundus Forms and Treatment of Strabismus 10

15 Accomodative Esotropia Children-usually comitant. No muscle weakness Adults - usually non comitant Acquired specific muscle(s) weakness Accomodative convergence reflex Glasses to control turn Often associated with amblyopia Surgery if glasses insuccessfull. Infantile Esotropia Develops after 3 months Refer when identified Early surgery (starting at age 6 months) 11

16 Exotropia Most often intermittent Fatigued Distant viewing Conservative management Surgery with frequency and/or large size Unusual forms of Strabismus 12

17 Adult onset Strabismus non commitment Non Comitant (specific muscle(s) Identify paretic muscle(s) Investigate etiology Inform Parents When Misalignment occurs REFER Surgery safe and effective Eyeball not removed May need more than one operation Both eyes often require surgery 13

18 Types of Surgery Recession- Resection- relax muscle strengthen muscle 14

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