Refractive Surgery in Children Indications and Non-Indications

Transcription

1 Refractive Surgery in Children Indications and Non-Indications Amr ElKamshoushy, MD Lecturer of Ophthalmology University of Alexandria Anisometropia Plano -4 Plano +4 1

2 Anisometropia Axial Refractive In anisometropia the difference is important Glasses for Anisometropia Plano -9 Plano

3 Aniseikonia Aniseikonia Spectacle Magnification 3

4 Spectacle Magnification RSM for AXIAL ametropia RSM for REFRACTIVE ametropia Knapp s Law Knapp s Law AXIAL myopia OD REFRACTIVE myopia OD 4

5 Knapp s Law In REFRACTIVE In AXIAL ametropia: ametropia: Optical correction at Optical correction at ant focal plane causes ant focal plane causes images on retina to images on retina to be equal in size be Unequal in size AXIAL myopia OD REFRACTIVE myopia OD Knapp s Law According to Knapp law: CL or lasik will induce aniseikonia in AXIAL And will correct it in REFRACTIVE AXIAL myopia OD REFRACTIVE myopia OD 5

6 Benjamin WJ. Borish's Clinical Refraction. 2 nd ed. St Louis. Butterworth-Heinemann -Elsevier,

7 Knapp law Optics of the actual physical size of the image formed on the retina. And, it has its limitations. Does the aneisokonia depend only on the physical size of the image on the retina? NO Aniseikonia Physical Perceived 7

8 Aniseikonia Physical Perceived Factors to be considered - Optical factors - Spacing of retinal elements - Distribution of cortical nerve fibers - Plasticity at higher visual system Aniseikonia Physical Perceived How to measure Aniseikonia? Space Eikonometer Aniseikonia Inspector Awaya test 8

9 Aniseikonia Physical Perceived Subjective measures aniseikonia is more reliable for the perceived aniseikonia even if in conflict with optical calculations. Glasses for Anisometropia Plano -9 Plano Children accept those glasses pretty well 9

10 Actual and perceived image size difference Static Aniseikonia Dynamic Aniseikonia Prismatic effect and induced anisophoria Prismatic effects and induced anisophoria 10

11 Prismatic effect of lenses Prismatic effect of lenses 11

12 Static Aneisokonia Induced Anisophoria (Dynamic Aniseikonia) Prentic Rule: Prism=Fxd Amount of induced prism for gaze 8 mm away from optical center: If the lens is -3 D 2.5 If the lens is -8D 6.5 If the lens is -12D 9.5 This can create problems in reading gaze positions 12

13 Benjamin WJ. Borish's Clinical Refraction. 2 nd ed. St Louis. Butterworth-Heinemann -Elsevier,

14 Child not wearing his glasses. Amblyopia getting worse Anisometropia due to corneal or lens problem 14

15 Any anisometropia > 4D - Child wearing his glasses. - Good vision OU - Good binocular vision 15

16 - Child wearing his glasses. - Not compliant with patching - Vision stopped improving Anisometropia > 15 D 16

17 - High anisometropia - Started glasses at older age - C/O: Diplopia on reading Part time glasses wear 17

18 - Undetermined compliance - Vision not improving as expected Thank You! Amr ElKamshoushy 18