Studies for Pseudophakia on Straylight, a Quality of ...wavefrontcongress.org/wp-content/uploads/2017/10/... · Studies for Pseudophakia on Straylight, a Quality of Vision Parameter

Studies for Pseudophakia on Straylight,a Quality of Vision Parameter

Tom van den Berg, physicist

Netherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences

[email protected]/straylightlab

WaveFr 5Mar16 TJTP van den Berg 1

c.r. disclosure

Royal Netherlands Academy of Arts and Sciencesowns patent on the Compensation Comparison method

for straylight measurementlicensed to Oculus GmbH for the C-Quant instrument


Introduction

Function indicators for cataract surgery

Subjective:patient, surgeon

Patient questionnaire highly unreliable on individual basis.Only around 10% of functional variance explained:

Steinberg et al. 1994, Lundstrom and Pesudovs 2009, van der Meulen et al. 2012, etc.

Objective:Visual acuity, gold standard (but confounded with refraction, and

retinal condition. Better: aberrometry based (Applegate, Thibos, Watson))Straylight (not confounded with refraction, nor retinal condition)

Straylight effects in pseudophakiaif added to VA as indicator for cataract surgery


large angle light spreading (straylight)versus

small angle effects (aberrations, double pass image)

5mm pupil

24°

20’2°

aberrometry double pass


Visual acuity1 min of arc => 0.02ºContrast sensitivity18..3 cycl/degree=> 0.06..0.33º

Visual acuity1 min of arc => 0.02º

Straylight >1º

Visual acuity1 min of arc 0.02º

The Point Spread Function (PSF)

Contrast sensitivity18..3 cycl/degree 0.06..0.33º

CIE 1999 standardCaucasian/normal/average/50y

Graphics by Ralph Michael

Ophthalmic andPhysiological

Optics 29 (2009)345-350


Objective assessment of straylight

Establish identity between the observed light and a reference light of known value

psychophysics


TJTP van den Berg 7

• International visual photometric principle (CIE)

• Bipartite field comparison of straylight to comparison light

• Functional value: straylight parameter “s”, given as log(s) (compare logMAR)

• Estimation of individual measurement reliability

Psychophysical method“Compensation Comparison”

Van den Berg, Coppens, FranssenARVO 2005

characteristics

Oculus C-Quant


1.0

1.3

1.6

1.9

2.2

2.5

1.0 1.3 1.6 1.9 2.2 2.5log(s) optical (2 methods)

aver

age

(n=4

) log

(s)

psyc

hoph

ysic

al

Testing the psychophysical methodusing scatter models of known value

Examples of scatter models

7 scatter models4 subjects

Ophthalmic and PhysiologicalOptics 29 (2009) ) 345-350

accurate assessment

of straylight in patients possible



In vitro straylight measurementŁabuz et al. Biomed. Optics Exp. 2015

Cuvette with light scattering sample (IOL)

Exposure sample (IOL)Observer

Sees only bipartite field

How does straylight compare to visual acuity?

Relation complaint Straylight

Simulations of patient visionfor typical early cataract values


average normal eye

visual acuity 0.4 decimal

straylight 2xincreased

“hazy vision”

signs in our institute’s elevator



increasedstraylight log(s)=1.4

against-the-lightface recognition

average normal eye



increasedstraylight log(s) = 1.47

upcoming headlightswhile driving at night

average normal eye


Subjective comparison of straylight and visual acuity

Questionnaire study in an (early) cataract population(Van der Meulen et al. JCRS 2012;38:840-848)

VFQ (37 questions; Mangione et al. NEI version 2000)and 5 Straylight focused questions (SLQ)

217 pre-op cataract patients


Typical questions in the questionnaires (simplified)

How difficult is it to read a newspaper?

How difficult is it to judge facial expression, because of your vision?

How difficult is it to check your clothing, because of your vision?

How difficult is it to drive a car during daytime in your own neighborhood, because of your vision?

How strong do you experience blinding while driving a car at night.

Scoring on a 5-point scale, from very bad, to no problem at all,transformed into average scales from 0 – 100.VFQ contains 37 questions, SLQ 5 questions


0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0.01 0.1 1 10 100

corre

latio

n ra

tio (n

orm

aliz

ed to

VFQ

vs

VA)

relative weigth VA/SL (leftmost pure SL, rightmost pure VA)

VFQSL-Qtotal-Q

correlation results questionnaire outcomes Van der Meulen et al. JCRS2012;38:840-848

Straylight and VA contribute in an approximate 1:1 relation

1 : 1straylight visual acuity


Population values

the normal eyelens aging/cataract formation

(quality assessment in refractive surgery,corneal dystrophies, dry eyes, albinism, vitreous

turbidity, …. )



0.4

0.7

1

1.3

1.6

1.9

2.2

2.5

10 20 30 40 50 60 70 80 90

log

stra

ylig

ht p

aram

eter

Age (years)

gray symbols: driver study(x=cataract; o=pseudophakia)orange symbols:cataract surgery study

Straylight increase with aging and cataract formationGray symbols EU driver study. Amer. J. Ophthalmol. 2007 144:358-363.

Orange symbols cataract surgery study. JCRS 2012 38:840-848.


0.4

0.7

1

1.3

1.6

1.9

2.2

2.5

-0.40 -0.20 0.00 0.20 0.40 0.60 0.80

stra

ylig

ht v

alue

(log

(s))

visual acuity (logMar)

straylight > 4x increased

better values visual acuitybelow driver norm

worst valuesgray symbols: driver study(x=cataract; o=pseudophakia)orange symbols:cataract surgery study

Straylight compared to visual acuity.Gray symbols EU driver study. Amer. J. Ophthalmol. 2007 144:358-363.

Orange symbols cataract surgery study. JCRS 2012 38:840-848.

Does cataract surgery help against straylight?

If so, what is the break-even point?

Or

what straylight level is to be expected in pseudophakia?


Oculus C-Quant

Straylight pre- and post routine cataract surgeryStraylight improvement factor 3.24 (sd 2.3)

(Visual acuity improvement factor 1.74 (sd 1.4))

95% chance of improvement log(s)=1.4(309 cataract surgeries)

normal phakic interval

Oculus C-Quant

Reference level log(s)=0.9


y = 0.0051x + 0.8622

0.40

0.70

1.00

1.30

1.60

1.90

2.20

30 40 50 60 70 80 90

straylight log(s)

age (years)

pseudophakicphakic normLinear (pseudophakic)

Cataract center. Van der Meulen et al. JCRS2012309 CE surgeries, no PCO.

-Only in a limited number of cases does straylight return to the young healthy reference level. -In most cases straylight much better than the phakic best-eyes norm.

-Age effect on pseudophakic straylight



y = 0.0040x + 0.87420.4

0.7

1

1.3

1.6

1.9

2.2

30 40 50 60 70 80 90

straylight lo

g(s)

age (years)

preoppostopphakic norm


Refractive surgery center; Lapid et al. submitted 2013; 160 lens exchange surgeries on good VA eyes (logMAR<0.1).

Same finding; in limited number of cases does straylight return to the young healthy reference level. In most cases postop straylight better than the phakic norm for best eyes. Age effect.


Literature survey on Straylight in uncompromised pseudophakiaŁabuz et al. JCRS 2015

The mean straylight value (± SD) for1,869 eyes is 1.21 (± 0.21) log(s) with meanage 68 (± 9) years.

24

Linear model of straylight-age dependency for 13 articles (lines). Line extent gives the age range. For 3 studies the regression line was not obtainable. The diamonds

represent the centers of gravity of the 16 individual datasets.


WaveFr 5Mar16 TJTP van den Berg

Predictability of improvement upon CEThe 558 available pre- and postoperative records were analyzed to assess

the Break Even Point (BEP) for pre-operative straylight (to achieve improvement).

25

Improvement of straylight upon crystalline lens exchange. The diamonds indicate the BEP of the different age groups

Literature survey on Straylight in uncompromised pseudophakiaŁabuz et al. JCRS 2015

WaveFr 5Mar16 TJTP van den Berg


Selected studies on IOLs

IOL deposits and calcification

A RaynerB HydroviewC Aquasense


.

.Mrs W., age 72 yearsVision complaints not corresponding VA.Extreme straylightLog(s) = 2.22 (20x)Deposit on IOL


Blundell, Knox Cartwright et al ARVO 2009, BJO 2010

Study eye lens: Hydroview B&L

Clinically opacifiedAround 5 x increased straylight(VA 25% loss)

“Clear”(not slitlamp detected)Around 2 xIncreased straylight(VA no loss)


0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

-30 -20 -10 0 10 20 30

scatter angle (degrees)

equi

vale

nt s

trayl

ight

val

ue (l

og(s

))

0122637B

0069262X

100x

10x

1x

Straylight from 2 explanted calcified Aquasense lenses

Porooshani et al ARVO 2008, van der Meulen et al BJO 2008


Diffractive multifocal

The edges of diffractive profilesscatter light


0.4

0.7

1

1.3

1.6

1.9

2.2

2.5

10 20 30 40 50 60 70 80 90

age

log(

s)

mono ODmono OSdiffractive ODdiffractive OSage normalage normal +2SDage normal -2SD

Straylight values 6 months after cataract surgery.

Multifocals give more straylight than monofocals

De Vries, Nuijts, Tjia,et al. JCRS 2008

+sd

- sd

referencelevel

Restor

Monof.


Comparison between diffractive multifocalsŁabuz et al. JCRS 2016 in press

Hydrophobic multifocal IOLs give more straylight (p=0.001)


Glistenings


0.00

0.50

1.00

1.50

2.00

0 0.5 1 1.5 2C-Quant full eye straylight value log(s)

glis

teni

ng c

alcu

late

d st

rayl

ight

val

ue lo

g(s) 6 eyes

straylight from glisteningscompared to total straylightlines indicate fraction of total(100%, 50%, 20%)

100%

50%

20%

In some cases may glistenings contribute significantly to straylight.

normal eye

(extreme) straylight

Large angle light spreading and visual acuity


Summary

Straylight measurement in vivo according international standard

Also possible in vitro, on IOLs, directly comparable to the clinical straylight measurement

Cataract surgery is efficient to reduce straylight, but room for improvement

Straylight from IOL associated problemscan be considerable

Straylight to be considered in IOL design

THANKS

Studies for Pseudophakia on Straylight, a Quality of ...wavefrontcongress.org/wp-content/uploads/2017/10/... · Studies for Pseudophakia on Straylight, a Quality of Vision Parameter

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