Enhancing accuracy of IOP estimation at the end of cataract surgery

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Enhancing accuracy of IOP estimation at the end
of cataract surgery

• Stanley M Chan MD, Ian Sutanto, Chad Baker MD
• Department of Ophthalmology, University of
  Alberta, Edmonton, AB, Canada

Authors have no financial interest
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Introduction

• - At the conclusion of cataract surgery, the
  surgeon pressurizes the eye to an acceptable
  level and ensures that there is no wound leak.
• - End of case IOP remains important to discern as
  even transient high IOP can further damage
  susceptible eyes.
• - Digital palpation has been shown to be
  generally inaccurate, however, experienced
  surgeons continue to rely on palpation to
  approximate IOP at the end of surgery.

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Questions

• 1) How good are we at estimating intraocular
  pressures by digital palpation?2) Is there a
  difference between an experienced staff surgeon
  and a resident?3) Is this a skill that can be
  learned?

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Methods

• - 100 cataract surgeries over 6 surgical days
• - After each surgery, the primary surgeon would
  estimate the IOP by palpation
• - The first assist would measure the IOP by
  Tono-Pen and inform the primary surgeon of this
  value
• - 67 eyes operated on by the experienced staff
  member as the primary surgeon
• - 33 eyes operated on by the chief resident as
  the primary surgeon

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How good are we at estimating IOP?
Bland-Altman Plot
The difference between the estimated (E) value
and the Tono-Pen (T) value increased at both
extremities of IOP.
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How good are we at estimating IOP?
Estimated IOP by digital palpation compared with
Tono-Pen measured IOP. Lines indicate points
that fell within 3 mm Hg and 6 mm Hg.
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Does experience play a role?
Staff 48 79
Resident 41 70
Within 3 mm Hg Within 6 mm Hg
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Can IOP estimation be a learned skill?
Estimated IOP, expressed as a percentage of
Tono-Pen IOP in order of surgical cases.
1) Solid outside lines show decreasing variance
of estimated pressure compared to Tono-Pen
measurement.
2) Area within dotted lines shows increasing
cases where estimated IOP is within 20 of
Tono-Pen measurement.
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Can this be a learned skill?
On days 1 and 2 combined, 29.5 of palpation
pressures were within 20 of the Tono-Pen
pressure On days 5 and 6 combined, 63.8 of
palpation pressures were 20 of the Tono-Pen
pressure
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Conclusions

• Estimation of intraocular pressure at the end
  of cataract surgery is often inaccurate, and
  cannot consistently identify eyes with pressures
  outside an acceptable range of 10-30 mm Hg.
• Digital palpation should not be the only means
  of measuring IOP if high pressures are a concern.

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Conclusions
- The experienced surgeon was more accurate at
estimating IOP than the resident. - With
increased experience and feedback using Tono-Pen
pressure measurements, it is possible to improve
the accuracy of IOP estimation.