Refractive status and its quantitative analysis

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Refractive status and its quantitative analysis
W F Harris Optometric Science Research
Group University of Johannesburg P O Box
524 Auckland Park 2006 South Africa wharris_at_uj.ac
.za
World Congress on Refractive Error Durban, March
14-16 2007
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W F Harris. Refractive status and its
quantitative analysis. A Rubin and W F
Harris. Distribution of refractive state in
developing South Africa. W F Harris and A S
Carlson. Affordable compensation for refractive
error. A S Carlson and W F Harris. Demonstration
of a system of affordable compensation for
astigmatism. A S Carlson. Potential methods of
refraction for rural areas in the developing
world.
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Effective delivery of healthcare requires a
knowledge of distributions in the communities
being served. There is a need, in particular,
for good quantitative methods of estimating the
distribution of refractive errors in
populations. Sphere, cylinder and axis.
Mathematical and graphical problems. Mathematical
ly orthodox representation Dioptric power
matrix. Symmetric dioptric power space.
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distributions
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trends
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Same power, different points
0o 180o
Graphs dont work.
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Maths doesnt work.
Sphere, cyl and axis mathematically unorthodox
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Symmetric dioptric power matrix
Fick HH, 1972-73 Long WF, 1976
dioptric power matrix, symmetric
coordinate vector
Deal Toop, 1993 Thibos LN, et al, 1994
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Symmetric dioptric power matrix
Inner-product space
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Symmetric dioptric power space
stigmatic
I
astigmatic
F
antistigmatic
O
K
J
oblique antistigmatic
ortho-antistigmatic
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Symmetric dioptric power space
stigmatic
I
astigmatic
F
antistigmatic
O
K
J
oblique antistigmatic
ortho-antistigmatic
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Graphical representation of symmetric dioptric
power space
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Graphical representation of symmetric dioptric
power space
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Graphical representation of symmetric dioptric
power space
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Summary
Effective delivery of healthcare needs data on
distributions. Requires suitable quantitative
methodology. Traditional quantitative
representation of refractive error is not
adequate for astigmatism. Dioptric power matrix
is suitable. Leads to concept of symmetric
dioptric power space for representing
distributions and doing quantitative analyses.
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Symmetric dioptric power space
stigmatic
I
astigmatic
F
antistigmatic
O
K
J
oblique antistigmatic
ortho-antistigmatic
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Acknowledgement This work is supported by the
National Research Foundation under grant 2053699
to W F Harris
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Graham, R. A variable focus lens and its uses.
J Opt Soc Am 1940 30 560-563
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