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

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.

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?

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

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.

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.

Does experience play a role? Staff 48% 79% Resident 41% 70% Within 3 mm Hg: Within 6 mm Hg:

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.

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

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.

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.