Visual Optics Lab Group Projects, November 2005

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Visual Optics Lab Group Projects, November 2005
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Visual Optics Lab Group Projects, November 2006
1. C4F1 Effects of aging on the ciliary muscle
and accommodation 2. C4G1 Radiometry and C4G2
Photometry 3. C4G3 Spectral Transmittance (of the
eye) 4. C4G4 Retinal Illuminance 5. C4G5 Effects
of incoherent radiation (on the eye) (a)
Mechanisms of damage 6. C4G5 Effects of
incoherent radiation (on the eye) (b) Protective
measures 7. C4D4 Point and line spread
functions 8. C4E8 Empty field and night
myopia 9. C2D3 Modulation transfer function
(Fourier optics) 10. C2B1, 4 Atomic energy
levels lasers theory of operation 11. C4G6 Effe
cts of coherent radiation (lasers) on tissue (a)
Mechanisms of damage (b) Wavelength, energy
levels, thresholds for reactions 12.
C4G6 Effects of coherent radiation (lasers) on
tissue (c) Ophthalmic applications (argon,
excimer, YAG, helium neon, krypton,
holmium) 13. Theory and Practice of Operation of
the Lensometer (Vertometer)
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1. C4F1 Effects of aging on the ciliary muscle
and accommodation
Relevance everyone eventually becomes
presbyopic. If we can determine the exact
mechanisms(s) of presbyopia, it may be possible
to substantially slow the process. Emphasis
review and critical evaluation of scientific
literature The classical theory of presbyopia
dates back to the time of Gullstrand (1908) and
has never been successfully replaced. According
to Gullstrands classical theory, presbyopia is
due primarily to hardening (sclerosis) of the
crystalline lens However, many promising
alternative theories have been suggested. Some
or all of these theories may be valid and may (at
least partially) explain the loss of
accommodation with age

• shrinkage of the ciliary muscle
• loss of elasticity of the posterior membrane of
  the ciliary muscle
• liquefaction of the vitreous resulting in loss of
  support for the posterior crystalline lens
• Continued growth of the crystalline lens,
  resulting in progressively more oblique zonular
  fiber insertion angle

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2. C4G1 Radiometry and C4G2 Photometry
Relevance radiometry is the basis of photometry
and photometry is used extensively in dealing
with the ability of the eye to see objects and
resolve detail. Dr. Norton (psychophysics) and
Dr. Loop (Visual Perception) will use photometric
units in their courses Emphasis explaining
concepts (e.g. making the connection between
luminance and brightness) Radiometry
describes electromagnetic energy (radiant
intensity, radiance, and irradiance). It does
not account for the ability of the eye to detect
that energy Photometry factors in the spectral
sensitivity of the eye to the above radiometric
terms to derive the terms luminous intensity,
luminance, and illuminance
http//www.coseti.org/9207-001.htm
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3. C4G3 Spectral Transmittance (of the eye)
Relevance this is part of the basis for the
spectral luminous efficiency of the eye, and
explains the risks associated with UV and IR
damage to the cornea, crystalline lens and
retina Emphasis literature search condensing
information to main points Spectral
transmittance is not a static property of the
eye. It changes with age (yellowing of the
crystalline lens) and with cataract development
or any other media opacities.
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4. C4G4 Retinal Illuminance
Relevance the amount of light reaching the
retina (retinal illuminance) can vary over a
range of several orders of magnitude. RI affects
many of the most basic processes of visual
information processing ability to resolve detail
(visual acuity), contrast sensitivity, color
sensitivity and discrimination, receptive field
size, temporal (flicker) sensitivity, etc. Dr.
Norton, Dr. Gawne, and Dr. Loop will emphasize
retinal illuminance in their courses. Emphasis
literature search condensing information to main
points combining photometric information with
neuroanatomy/biology
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5. C4G5 Effects of incoherent radiation (on the
eye) (a) Mechanisms of damage
Relevance UV damage to the crystalline lens is a
primary course of senile cataract UV damage to
the retina may be a primary cause of many
diseases UV damage will be covered in ocular
disease courses Emphasis literature search
condensing information to main points combining
photometric information with ocular disease
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6. C4G5 Effects of incoherent radiation (on the
eye) (b) Protective measures
Relevance part of the function of spectacles and
sunglasses is to block UV light (longer
wavelengths A and B, because most UV-C is
absorbed by the atmosphere). Dr. Gordon will
cover absorptive lenses in Ophthalmic
Materials. How effective are UV-absorbing
contact lenses? Dark sunglass lenses that DO NOT
absorb UV-A and B efficiently increase the UV
exposure of the eye and the risk
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7. C4D4 Point and line spread functions
Relevance describing real world images of point
objects. Explaining why larger pupil diameter
reduces visual acuity as does a very small pupil
diameter Paraxial optics says that the image of
a point object is a point image. Once we factor
in diffraction and aberrations, the image of a
point object is NEVER a point image but a point
spread function. Likewise, the image of a thin
line object is never a line but a line spread
function. Emphasis explaining concepts
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8. C4E8 Empty field and night myopia
Relevance when the eye has no visible objects to
focus on, it becomes myopic. This explains part
of the process of accommodation, i.e. that the
eyes resting state of accommodation is not fully
relaxed but partially accommodated (Resting
State Theory) Whiteout in a snowstorm, pilot
error in night flights, reduced visual
performance of emmetropes at night, etc. are all
due to empty field or night myopia
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9. C2D3 Modulation transfer function (Fourier
optics)
Relevance the MTF of the human eye describes how
efficiently the contrast in an object is
transferred to the retinal image. The function
is defined across a range of spatial frequencies
from very low (think large VA chart letters) to
very high (think tiny VA chart letters). It
describes many aspects of the visual performance
of the eye for large (low resolution) objects
versus small (high resolution) objects Fourier
Optics is based on the premise that any wave form
can be broken down into a series of sine waves.
It explains many aspects of the
neurophysiological behavior of the visual
system Emphasis mathematical concepts
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10. C2B1 4 Atomic energy levels lasers
theory of operation
Relevance lasers are used extensively in
ophthalmic surgery and in diagnostic instruments
(e.g. scanning laser ophthalmoscope). Emphasis
basic quantum optics energy levels, population
inversion, stimulated emission
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11. C4G6 Effects of coherent radiation (lasers)
on tissue(a) Mechanisms of damage
(b) Wavelength, energy levels, thresholds for
reactions
Relevance ophthalmic laser surgery techniques
photocoagulation (e.g. sealing retinal
hemorrhages), photodisruption (e.g. iridectomy),
and photoablation (corneal refractive surgery)
are all based on different laser properties. The
role of ocular chromophores, laser output energy,
laser power, wavelength, etc, is
important Emphasis basic quantum optics how
ophthalmic lasers perform the above functions
important laser characteristics
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12. C4G6 Effects of coherent radiation (lasers)
on tissue(c) Ophthalmic applications (argon,
excimer, YAG, helium neon, krypton, holmium)
Relevance applying the theory of ophthalmic
lasers to the practice of laser
surgery. Emphasis descriptions of procedures
why one laser would be chosen over another
recent advances in laser surgical techniques
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13. Theory and Practice of Operation of the
Lensometer
Relevance lensometer is used extensively in
optometric practice based on simple optical
principles Emphasis lensometer equations Badal
principle lensometer target position as a
function of lens power measuring prism with the
lensometer.