Spotlight: ON TECHNOLOGY AND TECHNIQUE
Caught in the Act
New technology measures accommodation, refraction, dynamic pupil range and gaze deviation, as they change -- from a distance.
BY CHRISTOPHER KENT, SENIOR ASSOCIATE EDITOR

Every year advances in medical technology bring us a little closer to the kind of instrumentation we've seen in Star Trek. Passing a handheld instrument over a patient's body and getting readings of internal conditions may still be a few years in the future, but a new instrument has just brought the field of eye care one step closer to the 23rd Century.

The POWERREF II, a new infrared videoretinoscope from Plusoptix, records and displays multiple measurements -- including accommodation -- in real time. Even more remarkable, it does so at a distance of 1 meter from the patient, without cycloplegia.

Measurement in motion

The POWERREF II takes dynamic, binocular measurements of refraction, accommodation, pupil size, interpupillary distance and angle of fixation, while simultaneously displaying a live video of the patient's eye movements during the measuring process. Because the measurements are recorded over time, you can adjust conditions and follow the resulting changes. For example, you can measure accommodation while the patient changes his plane of focus, or measure pupil diameter while altering the lighting in the test room.

The instrument consists of an infrared videoretinoscope, an infrared-sensitive CCD video camera and a PC-based control unit. When activated, the software locks onto the patient's pupils using autotracking technology; the instrument takes multiple readings and automatically determines the statistically correct outcome. The live, onscreen video of the patient's eyes lets you make objective assessments of eye movement and conditions as the measurements are being taken. (All measurements and video are digitally recorded for playback or storage.)

The POWERREF II can be used in four different modes:

Full refraction. In this mode, the instrument can take refractive measurements automatically, while displaying pupil diameter and gaze deviation OD and OS.

Dynamic. In dynamic mode, the instrument measures refraction, accommodation and pupil size, and provides an onscreen graph displaying the measurements over time as the patient accommodates or adjusts to lighting changes.

Screening. This is used to take a quick "snapshot" of spherical refraction only. It's primarily intended for refracting infants or noncooperative individuals.

Fixation map. In this mode, the instrument generates an onscreen graph showing gaze deviation in both eyes.

Features and benefits

The POWERREF II offers plenty of user-friendly features:

• The instrument can perform autorefraction on one eye or both eyes simultaneously.
• You can perform a complete "exam" on an average patient in 15 seconds or less. (This can have a positive impact on patient flow.)
• In dynamic mode, you can display the refraction and/or pupil size of either or both eyes on the graph in any combination. Once the measurement is taken, you can select any point along the graph, and the display will show the numerical measurements recorded at that moment.
• The numerical readouts change color to indicate when the instrument is making a clear, accurate reading.
• In full refraction mode, you can use the Autoshot feature. Autoshot lets the instrument decide when a reading is accurate, at which point it automatically preserves a "snapshot" of the measurements. (To use Autoshot, the patient's pupil diameter must be at least 3 mm wide; if necessary, this can be accomplished by dimming the lights in the examination room. A forthcoming upgrade will lower this minimum diameter to 2.5 mm.) Autoshot works in less than 1 second.
• You can save video and numerical data to your harddrive for future reference.
• It's easy to see a developing cataract in the video image. (In addition to being important medical information, this may indicate that the POWERREF's refraction data is less reliable because of the optical interference.)
• The instrument is designed to be easy to use, so that paramedical staff can operate it without supervision.
• The POWERREF II is ideal for refracting preverbal infants or noncommunicative patients. (The camera, which normally swivels from a point on top of the video monitor, can be lifted off the swivel and aimed manually when refracting an infant, or in other unusual circumstances.)
• The instrument is ideal for detecting visual problems such as anisometropia, anisocoria and strabismus.
• The POWERREF II easily measures night myopia.
• You can take a refraction through glasses, contact lenses or IOLs.
• The video image can be displayed in artificial colors that make it easier to observe refractive errors (a good way to confirm the numerical readings). (See image, above.)
• The POWERREF II is ideal for checking post-op results, such as the objective dynamic accommodation of an implanted IOL, the occurrence of aberration in night conditions following LASIK, or overrefraction through an IOL or contact lenses.
• The PC includes a CD ROM drive that allows you to burn data onto a CD for future reference.
• The instrument is upgradeable, with several upgrades already in the works.

It's worth noting that the refraction is based on the entire corneal region framed by the pupil. As a result, the refractive measurements take into account aberrations outside of the central cornea, which can affect visual acuity under low light conditions, such as when driving at night.

An idea whose time has come?

The POWERREF II has just become available in the United States, at a cost of $17,495; purchase of the instrument includes free upgrades for 1 year.

Plusoptix expects the POWERREF II to be especially useful for doctors working in three areas:

• Refractive surgeons will be able to document pupil size range dynamically at any brightness level before performing LASIK (a sensible precaution in case of litigation), as well as being able to monitor outcomes.
• Any M.D. will easily be able to measure dynamic accommodation.
• Doctors dealing with pediatric patients will be able to quickly capture an accurate refraction from 1 meter away.

PlusOptix is distributed exclusively in the U.S. through Refractive Dynamics Inc. For more information about the POWERREF II, please contact David Redfield at (215) 740-2489 or visit www.plusoptix.de, or send an e-mail to info@plusoptix.de.

Are you aware of new products or technology that have made (or are likely to make) a significant difference in practice? Contact Christopher Kent at kentcx@boucher1.com to find out about possible coverage in a future issue.