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Rainbow Glare as an Optical Side Effect of IntraLASIK Ronald Krueger , MD The Cole Eye Institute Ivey Thornton, MD The University of Alabama School of Medicine Thomas Van den Berg, PhD The Netherland of Ophthalmic Institute

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as an optical side effect of intralasik

Rainbow Glare

as an Optical Side Effect of IntraLASIK

Ronald Krueger , MD

The Cole Eye Institute

Ivey Thornton, MD

The University of Alabama School of Medicine

Thomas Van den Berg, PhD

The Netherland of Ophthalmic Institute

purpose
PURPOSE

To describe a NEW optical side effect associated with IntraLASIK, called

Rainbow Glare

background
BACKGROUND

Retinal images are affected by:

  • Diffraction
  • Aberrations
  • Light scatter
spectrum or irregularity from aberrations to light scatter
Spectrum or Irregularity from Aberrations to Light Scatter

Mrochen M, Semchishen V.

From Scattering to

Wavefronts- What’s in

Between?J Refract Surg

2003; 19: S597-S601.

aberrations vs light scatter
Aberrations vs. Light Scatter

Mrochen M, Semchishen V. From Scattering to Wavefronts- What’s in Between? J Refract Surg. 2003; 19: S597-S601.

monochromatic light source
Monochromatic Light source

“I see 12 spots of red lights surrounding the red stop light!”

“When I look at the green light,

I see 12 green spots of light instead!”

64 YOWM

3 mth s/p IntraLASIK

polychromatic light source spectrum of rainbow colors
Polychromatic light source- Spectrum of Rainbow Colors

“ Around white light, the lights are multi-colored!”

“they become 12 bars of lights with a prism pattern with colors like the rainbow!”

64 YOWM

3 mth s/p IntraLASIK

slide8

LightSource

Constructed by patient of Karl Stonecipher, M.D.

methods
METHODS

Retrospective review:

  • 585 eyes (312 patients) sequentially treated with IntraLASIK by R.K.
  • 6/04 to 8/05
  • Group 1: 399 eyes (215 patients) treated with our First IntraLASE
  • Group 2: 186 eyes (97 patients) treated with our Second IntraLASE
methods10
METHODS

IRB protocol

Post-operative questionaire were completed through clinic/phone

follow-up

  • Halo/ Starburst/ Glare
  • Transient Light Sensitivity
  • Rainbow colors around light
methods11
First IntraLASE

Pulse spot size

SMALLER cone angle/ numerical aperture of the focusing optics

Second IntraLASE

LARGER cone angle

Tighter Focus of pulses

Size of spot =SMALLER

Less Energy per pulse

Closer Spacingbetween the pulses

METHODS
methods12
Intra-Operative

Ablation Depth

IntraLASE settings

METHODS

Pre/Post Operative

  • Refraction
  • Visual Acuity
  • Pupil Size
  • Pachymetry
  • IOP
  • Wavefront Ab
  • Topography
  • Report of Symptoms
results
Group 1

contacted 194/215

patients (90.2 %)

H/G/SB 31.6%

Photophobia/TLS 21.3%

Rainbow Glare

37 pt in 69 eyes

19.3% eyes (19.1% patients)

Group 2

contacted 85/97

Patients (87.6%)

H/G/SB 32.1%

Photophobia/TLS 11.7%

Rainbow Glare

2 pt in 4 eyes

2.47% eyes (2.36% patients)

RESULTS

The spectral pattern most closely represented 4-12 radiating bands of rainbow colored light

results statistics
RESULTS- Statistics

Further risk factors related to model type:

IntraOp Raster Energy 0.04 0.005,0.36

IntraOp Spot Separation 2.8 1.2,6.2

results16
RESULTS

The level of refractive error in IntraLASE I eyes shows a greater incidence of Rainbow Glare in 26 out of 66 hyperopic eyes (39.4%) than in 43 out of 291 myopic eyes (15.17%)

  • Higher myopic eyes (> -6.00 D)= 21.43%
  • Moderate myopic eyes (-3.00 to -6.00 D)= 14.38%
  • Low myopic eyes (< or equal to -3.00 D= 8.82%
timing of rainbow glare
TIMING of Rainbow Glare

All patients except 1 stated that symptoms occurred immediately after IntraLASIK

  • One patient: 1 week post-operative

Rainbow Glare lasted

  • < 3 mth: 4.1%
  • 3-9 mth: 30.1%
  • > 9 mth: 63.0%
  • Fail to recall: 2.8%
spectrum pattern
SPECTRUM PATTERN

For each of the 73 eyes (39 patients):

  • 4 OR 6 bands= 17 eyes
  • 8, 10 OR 12 bands= 18 eyes
  • multiple bands= 12 eyes
  • 5 patients described a halo-like confluent annulus of dispersive rainbow colors= 10 eyes
  • 8 patient (16 eyes) could not recall the spectral pattern of the resolved rainbow glare.
discussion
Discussion

Known Spectral Phenomena in Ophthalmic Optics Include:

Lenticular Halo – causes a true annulus of rainbow color due to the spacings between the lens

fibers in the aging patient

(lens fiber spacing ~9 um)

Ciliary Corona – diffuse white and multicolored glare radiating from a point light source

  • Due to small particle light scatter

in pre-cataract lens

Light

source

discussion20
Discussion

Known Spectral Phenomena in Ophthalmic Optics Include:

Corneal Edema Related Colors – Rainbow-like pattern associated with an increase in fluid spacing within the stroma

Grating Filter Glasses – creates temporary spectral pattern for education and entertainment

Other - ? CrystaLens IOL ? LASIK?, etc.

slide21

INTRALASE™ Photodisruption

Gas & water are absorbed or liberated

when corneal flap is lifted

Not a cleavage plane that is created, rather

a photodisruption plane

or an array of microcraters

Back

Surface

The micro-irregularities of the back

surface of the flap can

create light scatter

slide22

Monochromatic

Red Light

Polychromatic

White Light

slide23

If the IntraLASE pulse pattern is lined up

perfectly from roll to roll…

The grating line is perpendicular

to the

spectrum

Directon of

Spectrum

Horizontal

vertical, or

even Oblique

spectral

pattern

slide24

Point

Light

Source

4 or 8

Bands

Of

Rainbow

color

slide25

Directiob of Spectrum

If the IntraLASE pulse pattern is not lined

up perfectly…

slide26

Point

Light

Source

6, 10, or 12

Bands

Of

Rainbow

color

angular extension is inversely proportional to the distance between the spot irregularities a

Ө

Angular extension (Ө)is inversely proportional to the distance between the spot irregularities (A)
  • A sin θ = m λ;Θ = angular extent, λ = wavelenth of light, A = grating constant m = diffractive order
  • The grating constant (A) is the periodicity of the grating lines.

λ (violet) = 450 nm, λ (blue) = 470 nm

λ (yellow) = 570 nm, λ (red) = 640 nm

slide28

Among our patients,The angular extent of the color ranged from 2-5 degrees of arc around point light sources, which could be calculated to correspond to a ~9 um sized spot separation within the corneal interface

The SAME spot separation setting

in the Intralase models

Ө

why is there a greater relative risk in group 1
Why is there a greater relative risk in Group 1?

The intensityof rainbow color is brighter when:

  • The Intralase creates bigger spot sizes
    • The intensity is proportional to the optical weight of the microcrater
    • Optical Weight = Volume X Change in Refractive Index
  • The number of grating lines is greater

The relative risk of Rainbow Glare increases with ablation depth.

  • This may be associated with more interface mismatch & optical weight due to the additional spacing created through increase ablation.
conclusion
Conclusion
  • Light scattering from the back surface of the IntraLASIK flap causes a constructive interference and is believe to cause ~20% Rainbow Glare Symptoms of Group I eyes.
  • The angular extent can be calculated to correspond to a grating size that matches the approximate raster spot separation of IntraLase.
conclusion31
Conclusion
  • Except for two patients, the Rainbow Glare symptoms was not observed in Group II eyes. This may be due to a tighter focus that minimizes the light scattering phenomenon.
  • Variance in the quality and numerical aperture of focusing optics can be optimized to minimize the phenomenon of rainbow glare as an optical side effect.
slide32

Thank you

for

your attention