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Love at first light or

Lights out all out

The Power

in

your Hands

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The Electromagnetic Spectrum

UV - Visible - IR

• UV is part of daylight and all around us.

• Contrary to normal day light, UV isn’t visible

• No one sees it coming .........the danger is hidden.

• UV-A light (315-400 nm) accounts 95% of the total exposure. It penetrates the tissues most deeply compared to other type of UV radiation.

• UV-B light (280-315 nm) causes more damage, because of higher energy.

• UV-C light (280-200 nm) and UV vacuum (<200 nm) is blocked by Ozone layer and does not reach surface of the earth.

What is UV light?

UV radiation can be divided into UV-A, UV-B and UV-C1:

• UV-A (315-400 nm) are the tanning rays, leading to premature ageing of the skin and some skin

cancers, retinal damage.

• UV-B (280-315nm) are the burning rays, responsible for the sunburns and eye conditions, eye

cancer and photokeratitis.

• UV-C (200-280nm) are the most dangerous rays, but fortunately those are blocked by the ozone

layer and cannot reach us.

Different type of UV

The main source for the UV that influences our eyes and tissues around our eyes, is natural sunlight.

UV is emitted also by artificial sources such as tanning beds, neon lights and energy saving lamps.

1 WHO Library Cataloguing-in-Publication Data

INTERSUN : the Global UV Project : a guide and

compendium. ISBN 92 4 159105 6

UV Part of the Invisible Spectrum

Vacuum UV

Far UV

UVC UVB UVA

40-200nm 200- 220nm 220-290nm 290- 315nm 315-400nm

Germicidal Erythemal

Increasing ENERGY Decreasing

Increasing Frequency Decreasing

Decreasing Wavelength Increasing

UVC used in Water Purification and Industrial Kitchens

Ultra VioletUV levels are always changing, the effect is based on:

• Concentration of atmospheric ozone

• Geographical location:

closer to the equator the more intense sola UV

• Increasing altitude

•Time of day and seasons

• Weather: clouds, dust, smog

• Reflection:Snow reflects up to 85%

Dry sand or concrete reflects up to 25%

Grass reflects up to 3%

Water 5-25%

https://earthobservatory.nasa.gov/features/UVB/uvb_radiation4.php

UV radiation and Spectacle Lenses

Dermatological Exposure to UV light is between the peak times of

10am to 2pm

Highest Ocular Exposure is typically 8am to 10am and 2pm to 4pm

when light hits at an angle , thus reflecting off the back surface of the

lens and entering the eye.

UV penetration into children's eyes

3x the annual sun exposure of adults*

10-13 year old

65% UVA

25% UVB

Vision council of America 2015

UV penetration in to an adults eye adults eye

1% to 3%

UV at retina

15 Years

47 Years

60 Years

70 Years

Natural ageing

of the lens of the eye

Age-related changes in the kinetics of human lenses: prevention of the cataract

Nicola Pescosolido,1 Andrea Barbato,2 Rossella Giannotti,2 Chiara Komaiha,2 and Fiammetta

Lenarduzzi

Every year some 16 million people in the world suffer from blindness due to

a loss of transparency in the lens.

WHO estimates suggest that up to 20 per cent of cataracts may be caused

by overexposure to UV radiation and are therefore avoidable

https://www.who.int/uv/faq/uvhealtfac/en/index3.html

Accessed June 2019World Health Organization. (1994). Environmental Health Criteria 160: Ultraviolet Radiation.

Geneva: World Health Organization

Consequently, 3 million peoples sight may be saved each year through the use of appropriate eye protection.

BS EN ISO 8980-3

Ophthalmic optics - Uncut

finished spectacle lensesPart 3: Transmittance specifications and test

methods

BS EN ISO 21987 : 2017

Ophthalmic Optics –Mounted spectacle lenses

UV reflected at the back surface of a spectacle lens

With UV cancelling A/R reflections are

neutralisedWithout UV cancelling

on average 20% reflected

(range 10 to 50%)*

K.Citek, Pacific University

« Anti-reflective coating reflect ultraviolet radiation»

Optometry 79(3), March 2008

• The lens material* absorps UV incident on the front of the lens and UV

neutralising MAR stops UV reflection on the back side of the lens

•UV-A light (315-400 nm) accounts 95% of the total exposure. It penetrates the tissues most deeply compared to other type of UV radiation.

•UV-B light (280-315 nm) causes more damage, because of higher energy.

•*1.53 index and above

UV neutralising Broadband MAR technology

gives

100% UV protection

The Eskimo Slit

Effects of UV on the Eye and

Adnexa of the Eye

Basal Cell Carcinoma

Cortical cataractPterygium

UV Keratitis

Advanced Lens Treatments

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The Visible Electromagnetic Spectrum – Visible Light

Visible

Light

http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html

7 million cones

120 million rods

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• Three types of cones are commonly

labelled by the colour at which they are

most sensitive

• The brain integrates the signals sent from

them so we see different colours

• The colour yellow results from green and

red cones being stimulated while the blue

cones have no stimulation

How we perceive colour

https://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_9/ch9p1.html

Blue Light

The shady side of Blue Light

• Blue light spectrum is 400–500 nm (indigo-blue-cyan)

• Blue light sources are: sunlight, artificial light and LED

• Blue light has a short wave lenght making it scatter more

• Scattering blue light causes blur and reduction of contrasts

http://www.thyon.com/files/content/blog/201209/spectrum-visible.jpg

The way we see the

world has changed

80% of Americans use digital

devices at least 2 hours a day

67% use 2 or more devices

simultaneously T

Between cell phones, computers,

tablets, TVs and other digital

screens, most people spend an

average of 8 to 10 hours a day

looking at screens.*

With peaks up to 15 hours/day* CaptainCook Research. Digital behaviour and digital

eye strain. Hoya, April 2017, the Netherlands and USA

T Vision Council of Americal Digital Eyestrain 2019

Two emerging topics related on blue light

AMDCircadian rhythm disruption

Photo sxc.hu/iprole

Circadian rhythm disruption

• Circadian rhythm is controlled by Melatonin

release

• It is secreted by Pineal gland located in the

• midline of the brain

• Pineal gland gets it signals via complex tract

1. Signals orign from Retinal Ganglion Cells that are stimulated to produce photoreceptor melanopsin

2. photosensitive RGC´s are most sensitive to short-wavelength (460 ∼480 nm) blue light and remain functional in the absence of rods and cones

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Tsang A H et al. J Mol Endocrinol 2014;52:R1-R16

Blue Light and Circadian Rhythm-

Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR)ISBN 978-92-79-26314-9

- Difficulties of getting sleep

- Quality of the sleep

- Influences the Dim Light Melatonin onset

Our Inner Clock

Some facts and figures

• Study in Belgium showed that 62% of children with an ave. Age of 13 who used

mobile phone after lights out (n=1656 av.) were found to be excessively tired.

• 35% of these cases could be attributed specifically to the

use of mobile phones

• Belgium study:Van den Bulck J. Adolescent use of mobile phones for calling and for sending text messages after lights out:

results from a prospective cohort study with a one-year follow-up. SLEEP 2007;30(9):1220-1223.

The Shady Side of Blue Light-

Myopic sensation

- Difficulties seeing blue neon signs in the evening

- Scattering blue light lowers contrast

Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) ISBN 978-92-79-26314-9

Blue light and vision

High Intensity Discharge (HID) lights and LED have impact on Pupillary

Light Responses (PLR)

PLR is driven by melanopsin-containing retinal ganglion cells that reacts

in continuous light conditions most strongly to short wave length. Rods

and cones reacts on initial rapid constriction.

Recovery to ”normal” dim light large pupil size can take up to 30 minutes

The minimal pupil sizes were recorded between 430-450 nm

Reference: Graef K., Schaeffel F. Control of accomodation by longitudinal chromatic aberration and bleu cones Journal of Vision (2012)

12(1):14,1-12

Age Related Macular

Degeneration

The known risk factors:

Age

Family History

Smoking

Gender

Ethnicity

Possible risk factors:

Alcohol

Obesity

High Blood Pressure

Sunlight

*American Macular Degeneration Foundation

15 Years 47 Years 60 Years 70 Years

Natural ageing

of the lens of the eye

1. M. Rozanowskaa, B. Rozanowskib, M. Boultonc “Light-Induced Damage to the Retina”

2. Reme C., Reinboth J., Clausen M., Hafezi F. Light damage revisited: converging evidence, diverging views Graefe’s

Arch Clin. Experiment Ophtholmol. 1996; 234 (1): 2-11

Three types of retinal

damage are:

Phototoxic- Light energy

*American Macular Degeneration Foundation

Age Related Macular

Degeneration

Thermal- Metabolism

Structural- Mechanical Damage

Ways to reduce blue light

1. Blue neutralising coatings

2. Tints~ Blue light reducing

3. Blue filtering Intra Ocular

Lens

4. Retina Care settings on

digital devices

Apple Night Shift

Advanced Lens Treatments

Blue Light

What we can say:

Blue light filtering coatings may reduce digital eye strain by reducing blue

light scatter there by increasing perceived contrast

Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances

Tsz Wing Leung ,Roger Wing-hong Li ,Chea-su Kee Published: January 3,

2017 https://doi.org/10.1371/journal.pone.0169114

Blue Light

Could

Might

Possibly

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The Visible Electromagnetic Spectrum

Visible

Light

How does the eyes sensitivity to light change

http://www.lrc.rpi.edu/programs/Futures/LF-auto/roadway.asp

Peak sensitivity 555nm

Peak sensitivity 497nm

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Disability Glare:-Disability glare is defined as loss of retinal image contrast as a result of intraocular straylight

Discomfort Glare:-Discomfort glare has been characterised as exacerbation or generation of pain as a consequence of light exposure which does not necessarily impair object visibility

Photo stress or Scotomatic Glare:-Scotomatic occurs when a light source quickly decreases visual sensitivity

Dazzling Glare:-Dazzling glare is a form of discomfort glare associated with disability glare

Dysphotopsia Glare:-Streaks, flare, central flash, and haloes from a point source of light represent positive dysphotopsia and dark crescents or shadows represent negative dysphotopsia

POLARISED LENSES

Light travels in open air as a wave bundle, with no specific orientation, vibrating in every direction. When light hits a

reflecting non-metallic surface such as water, snow, glass, it is reflected in parallel direction off the reflecting surface.

This is called Polarised light.

Due to this strong orientation in one direction, it has high intensity and causes glare for the observer.

Polarised Lenses

Polarised lenses have a special film, positioned in the lens during the casting process. This film is absorbing light

up to 98% in one specific direction.

For sunglasses the direction is horizontal, 0°-180°, to absorb the light reflected by surfaces that cause glare.

Polarised Lenses

Special Photochromics

DriveSafeDriving Lenses

Rodenstock Road

Flamework / Lamp work - Sodium Flare 589nm

Didymium GlassACE-202

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Cycling - polarising, yellow/amberGolf - green, neutral grey, yellow/amber, brownShooting - reddish-brown, orange, yellow to brown, greenSkiing - brown, red/orange, neutral greyTennis - greenFishing - polarisedMotor sports - polarising, yellow, redWater sports - polarising brown or greyRunning - green, neutral greyFootball, and fast moving ball sports - amber

Tints – Reduce Light Intensity and Improve Contrast

“Sport Tints”

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https://invisionmag.com/not-even-1-of-

people-score-perfect-on-this-color-test/

Select the darkest shade of Orange

1 2

3 4 3

How do you perceive colour?

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5 B E 9

Which number or letter

can you see

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• Photograph that became a viral internet

sensation on 26 February 2015,

• People disagreed over whether the

dress pictured was coloured blue and

black, or white and gold.

• The phenomenon revealed differences

in human colour perception

“The Dress”

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Himba of Namibia

COLOUR CATEGORIES AND CATEGORY ACQUISITION IN HIMBA AND ENGLISH DEBI ROBERSON, JULES DAVIDOFF, IAN R.L. DAVIES & LAURA R. SHAPIRO University of Essex, Goldsmiths College, University of Surrey and University of Warwick

Infra-Red – Invisible to naked eye

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IR-A: 700nm – 1400nm Near IR

IR-B: 1400nm – 3000nm Mid IR

IR-C: 3000nm – 1mm Far IR

Infra-Red Classification

Cambridge Ophthalmological Symposium | Published: 15 January 2016Does infrared or ultraviolet light damage the lens?•P G Söderberg•, N Talebizadeh•, Z Yu• & K GalichaninEye volume30, pages241–246 (2016

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Infrared

IR is found in many industrial settings including steel mills, textiles, paper

and glass manufacturing, or where lasers, arc lamps or electric radiant

heaters are used.

IR has a range of wavelengths, with near infrared being the closest in

wavelength to visible light, and “far infrared” closer to the microwave

region.

https://sciencing.com/infrared-light-effect-eyes-6142267.html

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Infrared

Skin exposed to IR provides a warning mechanism against thermal effect

in the form of pain.

Eyes, on the other hand, may not. Since the eye cannot detect IR, blinking

or closing the eyes to help prevent or reduce damage may not happen.

IR, particularly IR-A or near IR [700nm-1400nm], raises the internal

temperature of the eye, essentially “baking” it.

Medical studies indicate that prolonged IR exposure can lead to lens,

cornea and retina damage, including cataracts, corneal ulcers and retinal

burns, respectively.

https://sciencing.com/infrared-light-effect-eyes-6142267.html

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Mirrors

Infrared Protection Heat absorbing / reflecting

GLACIER+ UV IR

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GREEN ACE -IR

Hot flame work - Pyrex

Furnace work

EN-166

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Lights Out All Out

Thank You

Questions:

1/ According to a study at the Pacific University by Citek,

on average how much UV light is reflected by the back surface of AR coated lenses

a) 10%

b) 20%

c) 30%

d) 50%

2/ When is ocular exposure to UV at its highest?

a) 8am to 10am and 2pm to 4pm

b) 9am to 11am and 3pm to 5pm

c) 10am to 2pm

d) 12pm to 2pm

Questions:

3/ Which of the following statements is correct:

a) Blue light is recognised high risk factor - contributing to the development of AMD

b) Blue light emitted from digital devices is of an intensity that may damage the retina

c) Circadian rhythm is controlled by melatonin release which is influenced by Blue light exposure

d) Blue light focuses behind the retina giving a hypermetropic sensation

4/ According to a 2016 Vision Council of America report on digital media use,

what percentage use digital media more than 2 hours a day

a) 91%

b) 67%

c) 25%

d) 80%

Questions:

5/ Which of the following statements is correct:

a) Light reflected from matelic surfaces becomes polarised

b) Ace 202 glass is used by furnace work

c) The Himba people of Namibia have trouble distinguishing shades of green

d) Near IR has a wavelength of 700nm -1400nm

6/ What was the actual colour of ”The Dress”

a) White and Gold

b) Blue and Gold

c) Blue and Black

d) Green and Blue