To memorise Flashcards
What do radiant flux and luminous flux describe?
Amount of light emitted from a source
Units for radiant flux and luminous flux
Radiant flux: Watts
Luminous flux: Lumens
What is the peak photopic sensitivity of the eye?
555nm
Luminous efficiency of the eye is maximal at this wavelength - 1 watt = 685 lumens
What do radiant intensity and luminous intensity describe?
Intensity of light emitted from a source (amount of light per solid angle of space)
Units for radiant intensity and luminous intensity
Radiant intensity: watts per steradian
Luminous intensity: lumens per steradian = candelas
What do irradiance and illuminance describe?
Amount of light falling on a surface
Units for irradiance and illuminance
Irradiance: watts per sq metre
Illuminance: lumens per sq metre = lux
What is 1 steradian?
Unit for solid angle (cone shape)
Angle at the centre of a sphere which subtends an area on its surface that measures the square of its radius
What is one candela and how is a lumen derived from this?
One candela
= 1/60 of intensity radiated by a black body radiator at freezing point of platinum per sq cm
= 1 lumen per steradian
What do radiance and luminance describe?
Intensity of light reflected from a surface
Units for radiance and luminance
Radiance: watts/steradian per sq metre
Luminance:
- Candelas per sq metre
- Apostilbs (= 1/pi candelas / sq metre)
What is a troland?
Retina specific measure of illumination.
1 troland = retinal illumination when a surface luminance of 1 candela / sq metre is viewed through an entrance pupil which measures 1 mm2 after correction for Stiles-Crawford effect
Direct gonioscopy principle
Direct gonio contact lens has higher critical angle than cornea-air interface, allowing rays from the angle to exit via the goniolens –> real erect image
Space between cornea and lens is filled with viscous fluid
Direct goniolenses
Koeppe
Barkan
Swan-Jacob
Indirect gonioscopy principle
Indirect goniolens uses a mirror or prism to reflect rays from the angle
Inverted virtual image formed
Indirect goniolenses
Goldmann 3-mirror
Zeiss
Posner
Sussman
p-ANCA: what does it stand for?
Perinuclear anti-neutrophil cytoplasmic antibodies.
Stains myeloperoxidase
c-ANCA: what does it stand for?
Cytoplasmic ANCA
Stains proteinase 3
What is angular magnification?
D/4, where D is the power of the lens used
Iris / ciliary body development: what gestational age?
Week 12
Hox gene marks precursors
Lens development gestational age
27 days
Trabecular meshwork / aqueous humour formation gestational age
Week 20
When dods the hyalpid artery regress?
34 weeks
PAX6 chromosome
11
Rb chromosome
13
Suxamethonium MoA
Depolarising NMJ blockade
What is one apostilb?
Measure of luminance.
1 lumen / m2 or 1/pi candelas / m2
Holding a lens of unknown power over a cross on a page - with and against movement
Minus lens: cross moves with direction of movement
Plus lens: cross moves against direction of movement
What does the cavity of the optic vesicle become?
The subretinal space
When does the lens vesicle separate from the surface ectoderm?
33 days
