Diagnostic tool provides real-time data during cataract surgery

November 15, 2011

A newly launched diagnostic device and intraoperative tool enables real-time, on-the-table refractive measurements to guide decisions during cataract surgery.

Orlando, FL-A newly launched diagnostic device and intraoperative tool (Optiwave Refractive Analysis [ORA] system, WaveTec Vision) enables real-time, on-the-table refractive measurements to guide decisions during cataract surgery. It guides limbal relaxing incisions and enhancements, ensures correct placement of toric IOLs, and limits refractive surprises in post-refractive eyes.

As a clinical investigator evaluating the device, Dr. Donnenfeld, of Ophthalmic Consultants of Long Island, Rockville Centre, NY, had the opportunity to use it before its recent introduction and has also used an earlier-generation intraoperative wavefront aberrometer (ORange, WaveTec Vision).

The camera displays the patient's eye live during capture so that the surgeon can confirm that the eye is free of interference from instrumentation, draping, or speculum. This feature provides an additional level of control during measurement since the surgeon can detect erroneous measurements that result from external interference.

Expectations of today's patients

The system can help surgeons meet the high expectations of today's cataract patients, who do not want to experience pain or complications or undergo a procedure that involves sutures, injections, patches, or shields, Dr. Donnenfeld said. They want immediate, accurate visual rehabilitation, and by using the system to make adjustments during surgery, surgeons can, in most cases, deliver what their patients demand.

"Today, refractive cataract surgery has become mainstream, and ophthalmologists are challenged to deliver superlative outcomes with quality vision and minimal need for enhancements to give patients that 'wow effect' of the best possible vision on the first day after their surgery," Dr. Donnenfeld said.

In the past, surgeons relied upon preoperative measurements to determine which IOL was used. They also had to rely on best guesses instead of reliable data to determine how much astigmatism was induced by their incisions and use regression formulas to determine which IOL calculations were best to use following previous refractive surgery.

"Astigmatism management has been the most difficult area for ophthalmologists to grasp, and relying upon historical data and expected cylinder inducement by incision has really been suboptimal," he said.

It can be difficult to estimate the correct IOL power due to inaccurate corneal curvature measurements, measured keratometric values that are higher than the actual power, differences between the visual axis and the center of the cornea, or incorrect anterior chamber depth and IOL position.

"All this has changed now," Dr. Donnenfeld said. "For the first time we have a device that gives real-time intraoperative measurements of the patient's refractive error that allow the surgeon to adjust, titrate, and improve outcomes in a very simple manner with minimal use of time and significant improvement in clinical results.

"With the advent of the femtosecond laser, astigmatic incisions are going to have an increased prominence in ophthalmology, and with more reliance on improving outcomes, the . . . device allows us to improve our results with femtosecond refractive cataract surgery," he added.

Dr. Donnenfeld said he uses the system to refine his IOL selection in femtosecond refractive cataract procedures as well as in cases where the regression formulas break down, such as high myopia, hyperopia, and post-refractive corneas, and with very precise or demanding patients.

The system measures the aphakic spherical equivalent of the eye. Since the cataract has been removed, the true optical power of the eye can be assessed, and any induced astigmatism from the phaco incision is part of this measurement. The system then calculates a range of IOL powers that would yield postoperative refractions near the targeted outcome.

Dr. Donnenfeld also noted that the system can be used during femtosecond laser astigmatic keratotomies, which are now adjustable. His technique is to make the refractive incisions at the time of cataract surgery, open one of them, remove the cataract, use intraoperative aberrometry with the system to titrate the results while in the operating room, and open the second incision only if necessary to adjust results.

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