Optics Flashcards
Visible light lies between _nm and _nm
400 to 780 nm
UV - A is mainly absorbed by
lens
UV _ and UV _ are absorbed by
cornea and sclers
Light is perceived by three population of photoreceptors in the retina which are sensitive to light of ___, ___, ____
short - blue
middle - green
long red
Absence of green cone function
deuteranopia
Absence of blue cone function
protanopia
Absence of red cone function
tritanopia
Shift in spectral sensitvity of green cone function
deuternaomaly
shift in spectral sensitivity of blue cone function
protanomaly
shift in spectral sensitivity of red cone function
tritanolay
Red and green pigment is coded for on ___ chromosome
X chromosome
Blue pigment coded for on ___ chromosome
Chromosome 7
Acquired optic nerve disease leads to ________ colour defect with the excpetion of glaucoma and autosomal dominant optic neuropathy
red green
Glaucoma and autosomal dominant optic neuropathy can cause ___ colour defect
blue yellow
Acquired retinal disease tends to cause ___ colour fecet excep cone and Stargardt’s disease
red green
What is most comprehensive method of testing colour vision
Farnsowrth Munsell hue 100
Ishihara specifically tests for ____ defects
red green
Fluroscein is excited by ___ light of ____nm
blur light of 465-490 nm
FLuroscein emits _____ light of ____ nm
yellow green light of 520-530nm
______ occurs where there is an overlap in spectral transmission of excitation and barrier filters
pseudoautoflurosence
ICG aborbs ____nm and emits ____ nm ____ radiation
absorbs 805 nm and emits 835 nm infrared radiation
ICG is useful to see
choroid neovascularisation
Light waves in phase are called ____
coherent
light waves out of pahse are called ____
incoherent
destructive intereference occerns where in the eye
stroma of cornea
how is destructive interference eliminated in the stroma
spacing of the collagen bundles in the stroma
When light passes through a circular aperature, a circular ____ patternis producted
diffraction
The bright central disc in circular diffraction is called
Airy disc
What causes greater diffraction, smaller or larger aperatures
smaller
VEPs are electrical responses generated in the ___ cortex
occipital cortex
The phenomena of incident unpolarised light split into two polarised beam traveling in different directions is called
Birefringence
Normal steroacuity is ___ second of arc
60
Name 4 tests for steroacuity
Titmus, TNO, Lang, Frisby
The amount of light falling on a surface is called
irradiance
The anterior surface of the cornea acts as a concave/convex
convex mirror
when light enters a denser medium, the bean deviates ___ the normal
towards
refractive index of air
1.0
refractive index of water
1.33
refractive index of cornea
1.37
refractive index of lens
1.38-1.40
refractive index of crown glass
1.52
refractive index of flint glass
1.6
Convex mirror causes light to ___ is n2>n1
converge
convex mirror causes light to __ if n1>n2
diverge
what is the crtical angle for the tear film/air interface
48.5 degrees
a prism of one prism dioptre produces linear apparent fisplacem __ cm of an object at _ m
1cm of an object at 1 m
1 prism dioptre produces and angle of appparent deviation of ___
0.5 degrees
4PD test measures
small esotrpia/microtropia
in the 4PD test prism is placed base in or base out
base out
Right angle prism causes how much deviation
90 degrees
Porro prism causes how much deviation
180 degees, image inverted but not transposed
Dove prism causes how much deviation
No deviation, image inverted but not laterally transposed
convex lens causes convergence/divergence of incident light
convergence
concave lens causes convergence/divergence of incident light
divergence
green light of focimeter is used to eliminate
chromatic abberation
In the duochrome test the myopic eye see which colour background better
In the duochrome test the myopic eye see which colour background better
red
In the duochrome test the hypermetrorpic eye see which colour background better
green
the anterior corneal surface if ______ periphally than teh centre
peripherally
Iris reduces what type of abberation
spherical abbertaion
optimal pupil size is
2-2.5mm
Reintal cone are more sensitive to ligt whihc enters the eye paraxially compared to oblique light is called what effect
Stiles Crawford effect
what type of lens causes barrel distortion
concave
what type of lens causes pin cushion distortion
convex
coma results from what type of abberation
spherical abberation
long or short wavelnghts are diffracted more
long
the sky is blue because
scatter higher freuqency is scattered more than lower frequency
