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New concept and theory of Myopia development ____________________________

New concept and theory of Myopia development ____________________________. J.T. Lin, Ph.D New Vision, Inc. Taiwan. Beijing-8-2017. Summary. Human eye optics New concept of myopia The ratio: L/r =3.0 The growth rate theory The lens paradox Axial growth factors

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New concept and theory of Myopia development ____________________________

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  1. New concept and theory of Myopia development ____________________________ J.T. Lin, Ph.D New Vision, Inc. Taiwan Beijing-8-2017

  2. Summary • Human eye optics • New concept of myopia • The ratio: L/r =3.0 • The growth rate theory • The lens paradox • Axial growth factors • (defocusing, accommod) • (7) Myopia predictor

  3. Human eye optics S X Hyperopia Myopia F Retina D1 D2 CORNEA LENS

  4. Effective eye model (Lin, 2005) S X L P2 P1 CORNEA LENS L = S + X + aT 2 De = z [ P3 – P1/z – P2 ] z = (1- S/f) = 1- S P1/1336 = 0.8 to 0.85

  5. The basic myopic-theory (Lin, 2005) (1) Axial growth is triggered by (a) :retina defocusing, (b) (lens) accommondation (deshaping and translation). (2) Refractive errors resulted from the mismatching of ocular components growth rates De = Do + (dD1 + z2 dD2) - mdL initial cornea lens axial m=4.0 to 2.5 D/mm, (depnding on age) Conditions of emmetropization: (a) Do >2.0 ; (b) mdL < Do + [dD1 + z 2dD2 ] Otherwise, myopia [De<0] will develop due to anormal axial growth.(mdL)

  6. Myopia predictor Garner (2002), axial growth rate (per year) > 0.12 mm Olson (2007) regression Eq, (data, mean value) De= 110 – 2.43 L – 0.89 P1 - 0.62 P2 De=0, for L= 23, P1=43, need P2=24.8 D. Lin (2005), rate theory for L = 24 = S1 + S2 + T. De= 1.39 (S1 - 3.3) – 2.76 (S2 - 16.7) – 2.9 (T – 4.0) – 1.0 (43- P1) – 0.75 (23 -P2) 0

  7. New criterion for myopia-axial length L*=24 - 0.36(P1-43) - 0.23(P2-23) - 0.5(So-3.3) - 0.35(T-4.0) L*=24, for (P1,P2,So,T)=(43, 23, 3.3, 4.0) Example: L=26 mm could be myop or hyper, D= -1.5, if L*=25 D=+2.5, if L*=27 * JT Lin (Chin J O P, 2005, 145-151). CK Chang, JT Lin, IJO (8/2017). 0

  8. New definition of Refractive States Emmetropic has been defined by ratios: H/L =1.0, L/r =3.0 , L H New ratios: C1=L/r , C2=L/R L r R (1) C1=L/r=3.0 – 0.0036De (2) 0.25C1 +0.126 C2 = 1+2.97/L –L De * JT Lin (Chin J Oph opt. 2005, 1- 6; and 145-151). 0

  9. Shanghai/2005, N=3922 (data) Age 6-12 De =44.7 – 15.1 (L /r) L /r = 2.96 – 0066De Lin (theory, 2005) L /r = 3.0 – (0.003L) De =3.0 – 0.066 De, for L = 22 mm.

  10. N=167, age>40 De= 35.8 - 1.59 L Lin (theory, 2005) De = 62 – (2.76 L – 1.37 dS)

  11. Iribarren (Review,2016) Age 0 10-20 50 - 80 L (mm) 16.8 23.6 Cornea 51 43 43 Lens 34 19 21 - 19 Age 0 10-20 20-80 T 4.0 3.8 3.8 – 4.8 n 1.45 1.44 1.435c- 1.415 Lens paradox resolved by the index decrease by age, compensates the power increase due to thickness increase.

  12. Higher lens power in [short] eye hyperopes lower lens power in hyperopes with eyes with similar length as emmetropes. Irribennar (2015)

  13. Myopia predictor (Lin, 2005) Garner (2002, data), axial growth rate (per year) N > 0.12 mm Lin (2005, theory), dDe/dA = -m(dL/dA) – z2 (dD2/dA) axial lens = mN - z2 M solve for myopic predictor rate N = -z2 M/m. (012, Garner, 2002) Myopia onset age (A*) A* = A + (L-23)/N

  14. Growth (age 0 to 3 yrs), (Data: Lam, 2002) De 3.5 1.0 0 De drops fast by age 1. 0 3 6 Age (year)

  15. Ocular power growth (age 0 to 60 yrs) L, Dj Axial length 24 17 Corneal power Lens power 0 3 20 40 60 Age (year)

  16. Ocular power growth (age 0 to 60 yrs) +4.0 +2.0 0 Presbyopia emmetropia 0 3 20 40 60 Age (year)

  17. Conclusions • Axial growth is trigered by (a) :retina defocusing. • (b) lens accommondation (deshaping and translation). • (2) Refractive errors resulted from the mismatching of ocular • components growth rates De = Do + (dD1 + z2 dD2) - mdL initial cornea lens axial (4) Conditions of emmetropization: (a) initial hyperopic [Do > +2.0 ]; (b) axial power growth larger than the [corneal+ lens] power decrease, with a PERFECT match to the age-0 power.(Do) (5) Myopic on-set can be predicted, but it requires both age growth rate of the axial-length (N) and lens (M). . Garner predictor (N>0.12 mm) is not sufficient. (6) L/r ration of 3.0 needs revision to: 3.0 + 0.03L De.

  18. Lens paradox (preby with age) Refractive changes with (dashed) and without cataract Hashemi et al, Cli Exp Ophal (2015) Jongenelen et al, Vis Psy Phys Opt ( 2015)

  19. Eye-Accommodation dS • Lin’s 2-component theory (Lin, JRS, 2005) A = A1 + A2 A1 = M dS A2 = 83 (1/R’ – 1/R) M = (0.9 – 1.5) (D/mm) A2 = 1. 6 D (for dR= 1.0 mm) S R’

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