Optical aberrations Their significance for eye growth regulation

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Optical aberrationsTheir significance for eye
growth regulation?

• Chris Wildsoet

Howie Festschrift March 2002
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Howies Research Exploits
photorefraction, exotic animals
Children Chicks lenses aberrations
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Howie Always ready for a challenging subject!!
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Howie some of his reptilean friends
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some of his bird friends
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Howie at work
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Memories of visits with Howie Monica
Australia - Champagne breakfasts
picnics
Boston - the stairs!!
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Emmetropization the role of aberrations
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Ocular Aberrations I. Chromatic aberration -A
cue to defocus?
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Chromatic Aberrration (CA) Chick Studies
Chick has gt3 D CA!

• Wildsoet, Howland et al
• Rohrer Schaeffel

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Chromatic aberration not essential to
emmetropization?

• recovery from form deprivation myopia under
  yellow light

• (Wildsoet, Howland et al, 1993)

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Not all wavelengths compatible with
emmetropization?

• Lens compensation under red light
• No compensation under near UV light

• (Rohrer Schaeffel, 1992)

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What do accommodation studies tell us about CA as
a potential focusing cue?
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Accommodation CA

• Fincham
• poor accommodation with ML in some subjects
• Kroger Binder
• increased accommodation under red light
• Kruger lab
• accommodation poor when CA cues reversed
• over-accommodation with enhanced blue contrast

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Accommodation varies with wavelength
refractivity?

• Cross target at 33 cm

• Increased accommodation under red light (gt600
  nm)

• Colored paper response

• (Kroger Binder, 2000)

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Eye size varies with wavelength refractivity?

• Increased eye growth under red
  light (623.5 nm)

• 623.5 nm

• 534.1 nm

• 485 nm

• (Kroger Wagner, 1996)

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Chromatic aberration as a defocus cueIs there
evidence for chromatic tuning?
Strong redoverfocused?
Strong blueunderfocused?
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Blue cones signal hyperopic defocus?

• 10 sec recording 2 D stimulus

• Accommodation increases under enhanced blue
  contrast

• 420 nm target, 580 nm background

• Normal no CA

• 580 nm background

• (Rucker Kruger, 2001)

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A revisit to old data -Emmetropization in chicks
shows chromatic tuning!

• Eyes become more myopic (grow more?) under blue
  cf. red light

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A revisit to an old paradigmReverse chromatic
aberrtation lenses

• Question do reverse CA lenses disrupt
  emmetropization?

(Howland Wildsoet, on-going)
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Ocular Aberrations II. Monochromatic aberration
- Cue to defocus or the origin of abnormal eye
growth?
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Measurement of monochromatic aberration in humans

• Howland Howland aberroscope

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Monochromatic aberrations human myopia

• Myopes have lower 4th order aberrations
• Some low myopes have highly aberrated eyes
• Myopes show more negative SA, especially with
  accommodation

(Collins , Wildsoet Atchison, 1995)
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Higher order aberrations human myopia

• higher order (3rd) aberrations increase with
  myopia
• Low myopia internal corneal interact to
  decrease total aberrations
• High myopia internal corneal add up to
  increase total aberrations

• (Marcos et al. 2001)

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Myopic growth induces aberrations - Hints from
chicks

• Angular double-pass image width varies
  slightly with refractive error

(Coletta et al, 2000)
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SA as a cue to defocus?SA introduces asymmetries
in defocused retinal image

• -1/8D

• MTF with normal SA

0D
1/8D

• (Campbell, 2000)

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Two other sides of Howie

• Hi from Caroline!