A Valuable Tool for the Diagnosis and Management of Ocular Disease: Konan's CellChek

Todd D. Fladen, M.D.

The primary reason physicians should utilize the Konan CellChek is because it improves patient care. A secondary consideration is that specular microscopy has clear value from a reimbursement perspective.

Proven Clinical Utility

After becoming proficient with the Konan Contact Specular Microscope while completing my Cornea Fellowship with Peter Laibson, MD at Wills Eye Hospital in 1982, I brought this technology to my clinical practice in Canton, Ohio. This past year, our technology was upgraded with the new Konan Non-Contact CellChek XL Specular Microscope with Auto-Scan digital endothelial cell measurements and pachymetry.

Specular microscopy is performed on all cataract patients as a pre-operative risk assessment because I have discovered that having a precise endothelial cell count assists me in appropriately managing these cases. In the 90 day post-operative period, 30% of cataract patients exhibit some issue with their cornea such as edema. The CellChek XL has been of benefit in allowing me to proactively prevent problems.

Consider that more than one million cataract procedures are completed annually in this country with a failure rate of approximately 1%. This means that 10,000 patients experience complications with what is usually a straightforward procedure. For these patients in particular, physicians need to understand the cornea from a morphological viewpoint. Specular microscopy enables you to accurately quantify the endothelial function, identifies patients who are potentially problematic pre-operatively, and facilitates the appropriate treatment of that case. In general, if a patient has fewer than 1,000 cells per millimeter squared (cells/mm²), this patient's cornea is at risk.

KONAN CellChek XL Specular Microscope

Corneal Pathophysiology

At birth, the corneal endothelium is comprised of approximately 3,000 endothelial cells/mm². We know that endothelial cells are not replicated. What cells we're born with must last a lifetime. This monolayer of cells is unique in that, in order to repair itself, the cells must slide or stretch to fill any gaps. The basic premise of corneal swelling is that the endothelial pump is no longer functioning adequately enough to maintain normal corneal hydration. If the number of endothelial cells decreases too significantly, the endothelium also loses its ability to act as a barrier to fluid. Under normal circumstances, healthy cells can be retained, but trauma, inflammation, and heredity are possible factors that can impact the health of the endothelial layer.

Physical trauma can occur during cataract surgery or any other anterior segment intraocular surgery. Approximately 10 to 20% of endothelial cells can be lost during anterior segment procedures, which is significant. Techniques have evolved to prevent the loss of endothelial cells during cataract surgery such as the development of viscoelastic materials. However, even with these advancements, corneal swelling associated with cataract surgery still occurs.

Definitive Diagnoses

It is my view that every patient scheduled for intraocular anterior segment surgery, especially cataract surgery, secondary intraocular lens (IOL) surgery or IOL exchange should receive a baseline specular microscopy examination. If the cell count diminishes for whatever reason and the cornea swells, it becomes more challenging to obtain an accurate cell count. In Fuch's endothelial dystrophy, a genetic disorder more common in females, the endothelial cell count can prematurely decline with ensuing corneal swelling. The very formation of excrescences, deposits, or guttata alerts us to the fact that this cornea is more susceptible. These lesions signify that they have taken over positions normally occupied by healthy endothelial cells, interfering with optimal function. Following these patients pre- and post-operatively is helpful in monitoring their response to any operative procedure.

Distinctions of the CellChek XL

Since the CellChek XL is a non-contact device, the examination can be conducted without the use of drops and without causing discomfort. This instrument offers optical pachymetry readings in addition to providing highly magnified images that are clear and reproducible. This instrument can be used easily and accurately with little training. Finally, it features a small footprint and comes with a table, computer, monitor, and printer.

Using the Konan CellChek XL

In a basic specular microscopy examination, there are three ways of interpreting the images:

• Automated
• Manual count - a dot is manually placed in each cell or among a group of cells to initiate a count
• Users can place a box around groups of cells and place a dot in each box. This method is generally reserved for cases where substantial numbers of endothelial cells have been lost

The software analysis package provides the:

• Cell density in cells/mm²
• Standard deviation - compares the largest versus the smallest cell
• Coefficient of variation - reflects the rate of endothelial cell repair and the degree of polymegethism; a measure of the physiological stress
• 6A - indicates if the endothelial mosaic is physically stable

The CellChek XL can also identify and count all hexagonal cells. In addition, it provides statistical data including the number of cells used as the basis for the analysis.

CellScreen™ Software

A new advancement in this technology is the addition of a screening test, which provides an automated cell density count and an image of the endothelial cells. Since the screening is entirely automated, the user cannot choose which cells to count, slightly increasing the variability of the output. The results for both eyes are displayed simultaneously and the screening images are not saved. One of the advantages of the screening is that if problems are detected during the test, doctors are alerted to more closely question these patients and to look for associated signs in the tissues.

Clinical Case Report

The following case illustrates how specular microscopy makes a difference and can influence clinical decision-making. Following complicated cataract surgery, this patient presented with an aphakic right eye due to an aborted intraocular lens (IOL) implantation. The central corneal thickness of this aphakic eye was 578 microns. Specular microscopy revealed an abnormally low cell count in the right aphakic eye and a normal cell count in the left eye (see Figure 1). Once this low cell count was documented, the plan for a secondary IOL insertion was changed from implanting a standard anterior chamber IOL to a posterior chamber ReZoom™ Multifocal IOL (Advanced Medical Optics, Inc., Santa Ana, California), which was sutured to the iris with a Siepser slipknot. On day 2 post-op, the patient was elated with a distance visual acuity of 20/25 and J1 at near.

Without specular microscopy, you could conceivably cause harm to this patient, leading to a cascade of issues including the eventual need for a corneal transplant. By obtaining a quantitative measure of corneal function, physicians can definitively determine if the patient's cornea is more vulnerable.

Added Value - Reimbursement and Coding

For reimbursement by Medicare, medical necessity must be demonstrated. Specular microscopy may be indicated in situations in which the cornea is suspected of having an endothelial abnormality and in which the accuracy of the estimated cell count from slit lamp biomicroscopy is thought to be less than satisfactory.

Showing medical necessity can be achieved by the following:

• Patient reports symptoms such as blurry vision, especially in the morning; fluctuating vision; halos around lights; photophobia; foreign body sensation; contact lens intolerance
• Biomicroscopy findings such as guttata; corneal irregularity; polymegethism; pleomorphism (abnormal variation in the shape of the normally hexagonal cells); reduced cell density; increased corneal thickness; loss of transparency
• Deficiencies discovered during the CellScreen test

In our office, CellScreen tests are billed to the patient for a nominal fee. If any issues are discovered in the case history, biomicroscopy examination, or during the CellScreen examination, a complete CellChek examination can be performed and billed to the insurance company. Should the patient be found to have a diagnosed condition, we charge a medical evaluation and management fee and bill the patient's medical insurance using CPT 92286 (Special anterior segment photography with interpretation and report; with specular endothelial microscopy and cell count). In order to bill for the procedure, the physician must complete an interpretive report specifying the reason for the test, the cell count, a report of the findings, and the basic treatment plan. A sample interpretive report can be found in Figure 2.

It should be emphasized that if the only diagnosis is cataracts, endothelial cell photography is covered as part of the pre-surgical comprehensive eye examination or combination brief/intermediate examination provided prior to cataract surgery and not in addition to it. In other words, to bill specular microscopy at the same time that you are performing a pre-surgical eye examination for cataract surgery, the medical record must document at least one of the coverage criteria discussed and the procedure must be reported with a diagnosis code other than a simple cataract.

In instances in which Medicare may not cover the test, the patient should be asked to sign an Advance Beneficiary Notice prior to testing. The claim can be submitted as 92286-GA and the fee can be collected from the patient at the time of service or after the Medicare denial. In regards to repeat or follow-up testing, specular microscopy is reimbursable when medically indicated and consistent with locally accepted standards of practice, but the reason for testing must be clearly documented.

Return on Investment for Cataract Patients

The incidence of guttata or frank Fuch's endothelial dystrophy is approximately 2% to 4% of the cataract patient population. This is the reason why it is important to perform this test pre-operatively on all cataract surgery patients.

Embrace New Technology

Many physicians may believe that endothelial issues are rare and that technology such as the CellChek is not necessary. Practicing without the CellChek is like flying a plane with instrumentation only. You simply won't have a complete grasp of the situation.

In today's high tech environment, we have now been provided with the ability to quantitatively evaluate the endothelium. We can and should examine patients in high definition. The world of ophthalmology is going completely automated. Diagnosing conditions in complex and difficult cases is happily becoming more commonplace with instruments such as these.

Specular microscopy is an essential tool in my practice and should be embraced by every academic institution, corneal surgeon, and anterior segment surgeon. Clearly, for corneal issues, deep lamellar keratoplasty patients, and cataract surgery patients, specular microscopy is both invaluable and reimbursable.

Dr. Fladen is surgeon at The Fladen Eye Center in Canton, Ohio. He can be reached at [email protected]. Dr. Fladen has no proprietary or financial interest in Konan Medical USA, Inc.

References:

¹American Academy of Ophthalmology. Corneal endothelial photography. Three-year revision. American Academy of Ophthalmology. Ophthalmology. 1997 Aug;104(8):1360-1365.