Illumination, Glare Control, And Filters

Question 1

Review of illumination

Answer 1

• varies as the inverse of distance squared
• ergonomics vs economics. Brighter bulb or move it closer?
• effects of wavelength: Rayleigh scatter-particulate matter smaller than the wavelgnth of the incident light scatters shorter wavelgnth light more than long wavelgnth light

Move the light 2x as close=4x brighter

Question 2

Discomfort glare

Answer 2

Bright sunlight

Reflections off surface

Question 3

Veiling glare

Answer 3

Also affects contrast

Often not subjectively noticed

Question 4

Clinical aspects of illumination

Answer 4

-amount needed varies with age. 20-40-60 rule. Lose ability to read in the dark with age. 40y needs 2x as much as 20 year old illumanation to see, 60y needs 3x as much..etc..

Question 5

Position of source: illumination

Answer 5

-back to physics-angle of incidence=angle of reflection, so 45-60 degrees angle
-over the left shoulder doesnt work
Next to person, not behind or in front

Question 6

Type of lighting source

Answer 6

Closed top shade below eye level

-dont want an open top, light will be going up and away from you

Question 7

Type of bulb used

Answer 7

• avoid blue end of spectrum (most scatter, more veiling glare)
• CFLs do not work well for low vision pateitns
• LEDs good option, look at color temp
• “daylight” bulbs tend to work very well

Question 8

Pateitn education and lighting

Answer 8

• trial fram or over refraction add

- the ‘10 second demonstration’.

Question 9

Good lamps for low vision

Answer 9

OttLite
Stella Lamp
LED flashlights

Question 10

Sunglasses and filters for glare

Answer 10

Sunglasses

-overall depression of transmission curve of light

Question 11

Filters for glare

Answer 11

Selective elimination of specific wavelengths of transmission curve

Question 12

Difference of filters and sunglasses

Answer 12

Sunglasses are overal depression

Filters are elective of elimination of specific wavelgnths. Won’t make things darker and dimmer like a sunglass would

Question 13

Ordering filters

Answer 13

• by definition, filters must decrease or eliminate specific wavelengths of light
• tints only match color, not wavelength transmission
• many labs do not have or use a spectrophotometer and thus produce tints, not filters

Question 14

Metamer

Answer 14

Looks the same color but has a different transmission curve

-labs will make a tint instead of a filter for the patient. They just match the color, not the transmission curve

Question 15

Clinical perspectives

Answer 15

• manufacturers recommendations
• subjective response counts-take the patient outside to evaluate outside repsosne and light dark adaptation
• available options. Stock wraparound fitovers, prescription in dress or wrap frames, photochromic in some filters