Augenabteilung am St. Franziskus Hospital Münster

Influence of Mydriatic Eye-drops

on Wavefront-sensing and Automated Refraction

Taneri S, Oehler S, MacRae S M, Yoon G

The authors have no financial interest in the subject matter of this poster.

ASCRS, March 25-29, 2011, San Diego

Augenabteilung am St. Franziskus Hospital Münster

Background and Purpose• Wavefront-guided ablations are based on wavefront

sensing: in a pupil dilated under mesopic conditions (in this poster entitled ‘miosis’)orafter the application of mydriatic eye-drops (in this poster entitled ‘mydriasis’)

• Question: Is there an influence of mydriatic eye-drops on wavefront-sensing in terms of the phoropter-predicted-refraction (PPR) of the Zywave aberrometer or on automated refraction?

Augenabteilung am St. Franziskus Hospital Münster

Methods• Prospective study of 200 myopic eyes, measured in

dim light and pharmacologically induced mydriasis with an aberrometer (Zywave) and with automated refraction

• Comparison of Predicted Phoropter Refraction (PPR) for a pupil diameter of 3.5 mm with and without pharmaceutical mydriasis, respectively

• 100 eyes dilated with tropicamide 0.5% + phenylephrine 2.5% eye-drops, 100 eyes with tropicamide 0.5% alone

Augenabteilung am St. Franziskus Hospital Münster

MethodsRefractive Baseline of the 2 groups before pharmaceutical

mydriasis Tropicamide 0.5% + Phenylephrine 2.5% Tropicamide 0.5%

Mean SD Min Max Mean SD Min Max

AberrometerSphere(D) -4.02 2.49 -9.26 0.52 -3.85 2.75 -9.45 6.6

Cyl(D) -1.20 0.92 -4.21 -0.05 -1.25 0.98 -5.77 0.64

Axis (°) 1 180 2 180

SE (D) -4.62 2.46 -9.41 -0.32 -4.48 2.79 -9.84 6.16

AutorefractorSphere(D) -4.21 2.38 -9.0 -0.25 -4.04 2.30 -9.25 2.5

Cyl(D) -0.95 0.87 -4.0 0.0 -1.01 0.81 -4.00 0

Axis (°) 0 179 0 179

SE (D) -4.69 2.31 -9.38 -0.63 -4.54 2.30 -9.88 2.25

Augenabteilung am St. Franziskus Hospital Münster

Results: Aberrometer

• PPR values obtained in mydriasis were less myopic than in miosis

Mean ± SD

SE (D) Sphere (D) Cylinder (D)

Tropicamide 0.5% + Phenylephrine 2.5% -0.36 ± 0.36 * -0.33 ± 0.36 * -0.07 ± 0.27

Tropicamide 0.5% -0.24 ± 0.43 * -0.24 ± 0.35 * -0.00 ± 0.35

Difference between dim light pupil dilation and pharmacologically induced mydriasis

*: statistically significant

Augenabteilung am St. Franziskus Hospital Münster

Results: Sphere & Spherical Equivalent• Aberrometer and autorefractor displayed a hyperopic

shift of sphere and spherical equivalent in most eyes• Hyperopic shift of spherical equivalent with

tropicamide and tropicamide combined with phenylephrine was significant with both devices (aberrometer and autorefractor)

• No difference between the two mydriatic solutions were found

• Aberrometer was more affected by mydriatic eye drops than the autorefractor

• Age had no influence on the amount of the difference

Augenabteilung am St. Franziskus Hospital Münster

Z 3,-3 Z 3,-1 Z 3,1 Z 3,3 Z 4,-1 Z 4,-2 Z 4,0 Z 4,2 Z 4,4-0.05

0.00

0.05

0.03*

-0.01 -0.01 -0.01-0.01*

0.01

-0.02*

0.01 0.010.01

-0.01

-0.02*

0.010.00

0.01*

-0.01

0.000.00

group I group II

chan

ge o

f HO

A te

rms

[µm

]

Results: HOA

Group I: mydriasis with tropicamide 0.5% + phenylephrine 2.5%, n = 100Group II: mydriasis with tropicamide 0.5 %, n = 100

Applying tropicamide alone or combined with neosynephrine lead to significant inaccuracy in the determination of some HOA terms

Change of HOA after pharmacologic pupil dilation

Statistically significant

Augenabteilung am St. Franziskus Hospital Münster

Conclusion IEffect on lower order aberrations• There seems to be a cycloplegic effect from mydriatic

eye-drops as both aberrometer and autorefractor displayed a significant hyperopic shift of sphere and spherical equivalent in most eyes.

• The range of difference for the sphere component of the PPR was >1.5 D in both groups.

• This is much higher than the accuracy of modern excimer lasers and may partially account for clinically significant over- or undercorrection of defocus in laser vision correction.

Augenabteilung am St. Franziskus Hospital Münster

Conclusion II

The hyperopic shift after pharmaceutic pupil dilation should be taken into account when interpreting aberration measurements and

planning a wavefront-guided ablation.

Consequently, it seems ideal to avoid the wide-spread use of mydriatics prior to wavefront sensing by mathematical expansion of data

measured over a naturally dilated pupil.

Augenabteilung am St. Franziskus Hospital Münster

Thank you!