Intraoperative, real-time aberrometry during refractive cataract surgery with a sequentially shifting wavefront device.

PURPOSE

To introduce a new sequential wavefront device with rapid sampling that can be used as an intraoperative, real-time aberrometer/refractometer for immediate diagnosis and management of refractive outcomes during cataract surgery.

METHODS

A unique wavefront device uses a rotating prismatic mirror to rapidly shift the incident wavefront emanating from the eye through an aperture for analysis of a sequentially sampled wavefront segment. The sampled segment is then focused onto a quad detector that localizes its angular displacement of the sampled segment's wavefront gradient. Although the device's capability is higher for other applications, the wavefront is herein rapidly sampled at 200 Hz (frames/second), with a 2-mm aperture that moves along a 5-mm outer diameter annulus to capture a real-time analysis of refractive error for intraoperative application (ie, an intraoperative wavefront movie). The prototype wavefront device has been miniaturized into a narrow profile attachment that can be fixed to an operating microscope. In pilot analysis, several eyes undergoing cataract surgery were analyzed to determine both the qualitative and quantitative change in refraction with surgical intervention in an effort to document and improve outcomes intraoperatively.

RESULTS

Clinical application of the device was easily implemented without changing or limiting the working distance, magnification, or illumination of the surgeon's ergonomics intraoperatively. The real-time wavefront outcome was visualized overlaying a live eye image, presenting the refractive error both qualitatively and quantitatively. Qualitative representation of spherical refractive error was seen as a circle, cylinder as a thin ellipse, and emmetropia as a dot. Localization of lower-order aberrations with a practical sample rate of 200 frames/ second enables a real-time visualization of qualitative refractive data coaxially aligned with the eye image and quantitatively as sphere, cylinder, and axis at the bottom of the screen. Practical evaluation of residual cylinder prior to and during limbal relaxing incision placement, rotational accuracy during toric intraocular lens alignment, and refractive effect of subtle surgical maneuvers were all achieved with this device.

CONCLUSION

Real-time, intraoperative refraction and visualization is possible with a new sequential wavefront device attached to the operating microscope. The precision and accuracy of intraoperative documentation and refinement of outcomes is likely to be enhanced, making this an important future tool for optimizing cataract surgery outcomes.