A new sequentially shifting wavefront device for intraoperative aberrometry provides continuous feedback on refraction during cataract surgery.
Take-home message: A new sequentially shifting wavefront device for intraoperative aberrometry provides continuous feedback on refraction during cataract surgery.
By Cheryl Guttman Krader; Reviewed by Ronald R. Krueger, MD, MSE
Cleveland-A novel intraoperative aberrometer with a new sequentially shifting wavefront device (HOLOS IntraOp, Clarity Medical Systems) brings diagnostic precision in cataract surgery to a level that meets the therapeutic precision of premium IOL and femtosecond laser technology, according to Ronald R. Krueger, MD, MSE.
“Despite advances in preoperative measurements and methods for improving the accuracy of toric IOL alignment, about 20% of patients require some kind of enhancement to correct refractive error after cataract surgery,” said Dr. Krueger, medical director, Department of Refractive Surgery, Cole Eye Institute, Cleveland Clinic, Cleveland.
“Real-time intraoperative aberrometry for measurement of astigmatism and confirmation of IOL power has the potential for refining any of the preoperative measurements we are making,” Dr. Krueger said. “Therefore, it should lead to better refractive outcomes, which is important in the current era where success in cataract surgery is measured by uncorrected visual acuity.”
The intraoperative aberrometer is a miniaturized wavefront device that attaches onto the bottom of nearly any operating microscope.
“The device is very simple to integrate into the surgical environment. It does not compromise ergonomics for the surgeon or the scrub nurse, and with its thin profile, sufficient clearance is maintained for surgical instrument handling,” said Dr. Krueger, who is also professor of ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland.
The aberrometer uses a rotating prismatic mirror that rapidly shifts the incident wavefront from the eye through a variable-size aperture.. As the aperture moves along an annulus, the sampled wavefront segment is focused onto a quad detector that senses the location of the scanned spot as a function of the detection geometry. Refraction is determined by the magnitude and axis of displacement of the rapidly scanned spot.
The refractive measurements are displayed qualitatively using outlines of geometric shapes. Spherical refractive error is represented by a circle, cylinder as a line along its axis, and these two shapes collapse into a dot when emmetropia is achieved. Quantitative refractive data are also presented.
All of the information is generated in real-time, without the surgeon having to push a button to capture the refraction, and seen in a heads-up display on a color monitor.
“The device continuously samples the wavefront at a rate of several times per second and provides immediate feedback to the surgeon about the refraction, which is important considering the number of variables that can affect the measurement,” Dr. Krueger said.
“For example, if the speculum moves and bumps the orbit, the refraction will change, but the surgeon will know immediately that something has happened,” he said. “The competitor intraoperative aberrometer has been enhanced with technology that provides continuous streaming refractive data, but the actual measurement is still a snapshot, which can be misleading.”
Ronald R. Krueger, MD, MSE
This article was adapted from Dr. Krueger’s presentation at the 2014 meeting of the American Academy of Ophthalmology. Dr. Krueger is a consultant to Clarity Medical Systems, but has no other relevant financial interests to disclose.