Spotlight ON TECHNOLOGY & TECHNIQUE

Delve Deeper into Corneal Exams

CellChek XL provides earlier assessment for better treatment.

By Leslie Goldberg, Associate Editor

As good as biomicroscopy may be, concerns about its relative inability to properly visualize the corneal endothelium can give pause to even the most seasoned slit-lamp jockeys. For patients with suspected corneal dystrophy, trauma, infection or other history of corneal disease, specular microscopy is essential to properly gauge the density, integrity and health of the endothelium.

A specular microscope is of course standard equipment in any corneal specialist's office, but even general ophthalmologists are enjoying the clinical and practice-building benefits of the technology. And generalists and specialists alike will appreciate the enhanced precision and ease of use inherent in Konan's CellChek XL, the latest in its specular line.

The CellChek XL captures consistent, high-quality images using a patented method identifying the position of the cellular interface. The instrument automatically performs final alignment and fine focus and then captures an image, Konan says. It provides five fixation points for image capture, at the center of the cornea and four peripheral sites. The software allows users to record the location where images are captured, review patient history, track changes with time notation and link the scans to an electronic health record. It also measures corneal thickness at all five target sites using non-contact technology.

Physician Feedback

"It's probably my favorite device to use in the office, because it gives me such a concrete ability to look at what's essentially the holy grail of the cornea," says corneal specialist George Rosenwasser, M.D., of Hershey, Pa. He says it's essential in screening Fuchs' or nonguttate endothelial dystrophy patients prior to cataract surgery, or doing the detective/diagnostic work after anterior segment surgery gone wrong. "It lets me know if the cornea is strong enough to undergo an intraocular procedure," he says. "It's the most concrete teaching tool we have for patients and their families, especially when a corneal transplant is being contemplated." His practice is also currently using the device in a prospective study to measure cell density after Descemet's stripping and automated endothelial keratoplasty.

He points out that non-contact specular microscopy, pioneered by Konan, has been revolutionary for corneal specialists. "The early contact devices were difficult to use and uncomfortable for patients," he says, "so they were only used in dire straits." By contrast, he now uses a non-contact device such as the CellChek XL "virtually on a daily basis," adding that the Konan trainer was "fabulous," spending half a day with the staff putting the device through its paces, and the installer ensured that it integrated flawlessly with his EMR system.

"We are living in a digital world," says Todd Fladen, M.D., who's been using Konan specular microscopes since 1982. "The evaluations of all aspects of the eye are digital. Our EMR is digital, measuring the curvature of the cornea is digital, there is digital imaging for visualization of the anterior segment — a specular microscope is just a part of this age."

In his Canton, OH, practice, specular microscopy is performed on all cataract patients as a preoperative risk assessment; having a precise endothelial cell count assists him in appropriately managing these cases, he says.

He says that using a specular microscope as a surgical tool makes him more meticulous. "When I perform cataract surgery, I have a 99% success rate. I'm focusing on the 1% to reduce those possibilities of going into the surgery with problems and to try to better predict their outcome. Endothelial microscopy, for me, is a means to that end," says Dr. Fladen. He says that other advantages of the CellChek XL is that it is cost-effective, has a quick learning curve and helps to document normal from abnormal cases and follow progression. "It's best use is on primary diagnosis," he adds.

Putting it Into Practice

The figure on the next page shows the specular endothelial cell analysis of a 68-year-old female who underwent complicated cataract surgery with a dropped nucleus requiring vitreoretinal intervention. She presented to Dr. Fladen for secondary IOL implantation. Her VA is refractable to 20/20. Her cornea is clear and her corneal thickness was 569 by pachymetry, using an average of 25 measurements.

The figure shows dramatic loss of endothelium despite a physically normal-appearing cornea with normal thickness. However, the cell density shows her corneal function is marginal. "This is analogous to a patient with a creatinine of 2.9 and normal urine output but markedly reduced renal function and at grave risk for fluid overload," says Dr. Fladen.

"I admit this is not the routine case, and for many, simply following corneas with pachymetry and subjective grading of guttatae works reasonably well," says Dr. Fladen. "But if you begin to photograph every cornea preoperatively, at no charge and as part of your comprehensive cataract workup, you will quickly find patients who are at risk of developing acute cornea edema after routine and expedient cataract surgery."

Dramatic loss of endothelium despite a normal-appearing cornea with normal thickness.

Dr. Rosenwasser adds that screenings in his corneal specialty practice allow him to identify subclinical dystrophy, especially in relatives of corneal transplant patients. "We'll image family members in any case with a familial predisposition" to corneal abnormalities. Often, this leads to diagnoses that might have gone undiscovered, he says. He also uses it to screen refractive surgery patients, as most are below the age of easy detection for common endothelial pathology such as Fuchs. "This is an excellent, non-invasive method of evaluation of corneal health with negligible risk."

The device is especially good at serial imaging for long-term follow-up, Dr. Rosenwasser says. "It maps five positions for alignment, so that you know that you're looking at same location on subsequent exams." He adds that its corneal thickness readings offer a "pretty good correlation with ultrasound pachymetry." OM

For more information on Konan's CellChek XL, visit www.konan-usa.com.