Comparison of Pupillometer With Pupillometry Function of Binocular Free-Viewing Autorefractor

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Comparison of Pupillometer With Pupillometry
Function of Binocular Free-Viewing Autorefractor

• Charles D Cohn, MD Jay C Bradley, MD
• Peter W Wu, BS Sandra M. Brown, MD
• The authors have no financial interest in
• the subject matter of this poster

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Background

• Accurate measurement of the dark-adapted pupil
  diameter (DAPD) has become a standard element of
  the pre-operative assessment for corneal and
  intraocular refractive surgery
• Most pupillometers in clinical use occlude one
  eye, which theoretically enlarges pupil size by
  halving the total retinal light flux
• No independent clinical data have been presented
  comparing a monocular device to a binocular
  free-viewing device

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Purpose

• To assess the performance of a binocular
  free-viewing autorefractor with pupillometry
  function against a monocular occlusion
  pupillometer (Neuroptics Pupillometer or NOP) of
  known clinical performance.
• Note The NOP has been validated in previous
  studies to be reliable under our test conditions.1

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Devices Used
WAM-5500 Binocular Accommodation Instrument (FVAR)
NeurOptics pupillometer (NOP)
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Methods

• All subjects were volunteers without strabismus,
  prior intraocular surgery, or trauma affecting
  pupillary shape
• Device test order and eye test order were
  randomized
• All subjects were dark-adapted prior to testing
• 50 patients, divided evenly into groups by age,
  were tested under 1 lux and 7 lux ambient
  illumination with controlled distance fixation at
  20 feet
• Testing with the FVAR was done with both eyes
  open (binocular) and repeated with one eye
  occluded (monocular)
• Testing with the NOP was repeated until a
  standard deviation lt0.07 mm was obtained

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Results

• FVAR had clinically unacceptable outliers of
  0.5 mm in DAPD at both illumination levels tested
• At all age decades, FVAR underestimates DAPD
• Right or left eye testing order and which device
  was tested first did not affect results

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Results

• The FVAR is quite sensitive to small degrees of
  parallax and decentration and significant effort
  was required to obtain measurements even in fully
  cooperative subjects.
• The FVAR takes only one measurement of pupil size
  instead of averaging several measurements and
  providing a standard deviation (SD)
• Pupil size is larger when occluding one eye when
  testing with the FVAR

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Results
Mean DAPD (in mm) as a function of age for the
NOP FVAR at 1 7 lux
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Results
Difference in DAPD (in mm) between NOP
Binocular FVAR
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Results
Difference (in mm) between right eye DAPD with
left eye occluded and with both eyes open using
FVAR
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Conclusions

• The WAM 5500 pupillometry function frequently
  disagreed with the NOP by 0.5 mm in DAPD.
• Testing the first eye with the NOP does not
  induce sustained pupillary constriction that
  biases the result of the second eye.
• The FVAR is technically more difficult to operate
  than the NOP
• FVAR accuracy may suffer since the device obtains
  only a single measurement instead of averaging
  several
• FVAR measurements suggest pupil size is larger
  with one eye occluded

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References

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  Clinical performance of a handheld digital
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  Monocular versus binocular pupillometry. J
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