The Surgeon's Role in Inducing and Controlling Motion Errors During Intraocular Membrane Peeling Procedures

Abstract

Objectives: To understand the surgeon's role in inducing and correcting movement inaccuracies during intraocular membrane peeling procedures.

Materials and methods: Optical sensors were used to record movement errors during actuation at the distal tip of 23-gauge pneumatic forceps both when the handle was handheld and when fixed with no human contact. Movements were also recorded at the proximal part of the forceps shaft (near the sclerotomy site) and compared to movement recorded at the distal end. The root mean square (RMS) and range values of the signals obtained from the sensors were calculated before and after applying high (7-13 Hz) and low (<5 Hz) frequency filters.

Results: Comparison of RMS and range values of movement errors at the distal end of the forceps during actuation when the forceps handle was fixed and handheld showed that without human contact, these values were significantly lower in the X axis at all frequencies and in the Z axis at high frequencies compared to handheld (p<0.05), while there were no significant differences in the Y axis. Comparison of values from the distal and proximal ends of the forceps showed that when the forceps were fixed, RMS and range values were significantly higher for movement errors at the distal end compared to the proximal end at all frequencies (p<0.05). There was significant positive correlation between the extent of actuation and the RMS and range values for high-frequency movement errors but not low-frequency errors in all three axes with the fixed pneumatic handle (r=0.21-0.51, p<0.05).

Conclusion: Surgeon- and non-surgeon-related errors are apparent in all axes, but skilled surgeons correct these errors through visual feedback, resulting in better correction in the visible planes. Sclerotomy sites provide a pivoting and stabilizing point for the shaft of the forceps and it is likely that skilled surgeons make use of the sclerotomy point to dampen motion errors, a skill worth teaching to beginners.

Keywords: Vitrectomy; epiretinal membrane; intraocular forceps; macular hole; surgical errors.

Figure 1

The system used to record movement errors. 1: Pneumatically powered handle (Constellation pneumatic DSP). 2: Specially designed slot for secure attachment of the handle to the hemisphere that houses the optical sensor, to eliminate surgeon related errors. 3: A plastic hemisphere, housing 3 optical sensors to monitor movements in directions X, Y, and Z. 4: An optical sensor attached to the shaft of the forceps to monitor the extent of actuation. 5: Plastic panels designed to translate movements from the proximal part of the shaft of the forceps, closer to sclerotomy site. 6: Proximal attachment location. 7: Plastic panels designed to translate movements from the distal part of the forceps away from sclerotomy site. 8: Distal attachment location. 9: Optical sensors detecting movement errors in the Y axis. 10: Optical sensors detecting movement in the Z axis. Note optical sensors detecting movements in the X axis are located behind the forceps. 11: The definition of the X, Y, and Z axes in relation to the distal end of the forceps

Figure 2

Movement errors before applying frequency filters detected in the X, Y and Z axes along with actuation extent recorded for pneumatically driven forceps being held by hand but pneumatically actuated by foot pedal