The cornea is the transparent structure that forms the anterior one sixth of the outer coat of the eye and is responsible for more than two thirds of its refractive power. The cornea consists of several layers, including the epithelium, stroma, and single-celled endothelium. The endothelium is the most posterior layer, interfacing with the aqueous humor of the anterior chamber of the eye. Corneal clarity is dependent on a relatively dehydrated state. The endothelium plays a key role in maintaining dehydration by both preventing aqueous humor from entering the cornea and by pumping fluid from the corneal stroma into the anterior chamber. The corneal endothelial cells do not replicate. When destroyed by disease or surgery, the remaining cells enlarge and spread out to cover the posterior corneal surface, thus decreasing the cell density (cell count). Corneas with extremely low endothelial cell densities can no longer maintain a dehydrated state. The corneas may decompensate, swell, and become cloudy over time, with an associated loss of visual acuity.

The slit lamp (or biomicroscope) is commonly used to assess the status of the cornea and corneal endothelium. However, the specular microscope provides a magnified view of a small area of corneal endothelial cells to measure and record endothelial cell counts of the cornea. This technique is also known as corneal endothelial microscopy (CPT code 92286). Images of the endothelium seen with specular microscopy can be recorded on videotape or photographic film to facilitate estimates of endothelial cell density and configuration. The cell density of an individual’s cornea can then be compared to a previously documented normal range, allowing for a rough estimation of the ability of that cornea to withstand damage from surgical or other trauma.

Corneal endothelial microscopy has been frequently used as a pre-operative test before intraocular surgery to identify patients at risk for corneal decompensation after surgery. In this setting, the most common application has been cataract surgery. In addition, corneal endothelial microscopy has been used in patients with corneal endothelial dystrophies, including Fuchs’ endothelial dystrophy, posterior polymorphous dystrophy, and iridocorneal endothelial syndromes. Finally, specular microscopy has been widely used in the evaluation of donor tissue for corneal transplantation.

Corneal endothelial microscopy may be considered medically necessary as a pre-operative test before intraocular surgery (e.g., cataract surgery) in order to identify patients at risk for postsurgical corneal decompensation.

Corneal endothelial microscopy may be considered medically necessary in the diagnosis and management of patients with corneal dystrophies or other corneal abnormalities.

BlueCard/National Account Issues

No additional reimbursement is recommended for corneal endothelial microscopy. Charges for this procedure should be considered as part of the evaluation and management of the patient, and no additional reimbursement is recommended for CPT code 92286 (special anterior segment photography with interpretation and report; with specular endothelial microscopy and cell count). This recommendation is consistent with Medicare policy.

Current Medicare policy states that corneal endothelial microscopy may be medically necessary in the following patients:

• With slit lamp evidence of endothelial dystrophy;
• With slit lamp evidence of corneal edema;
• About to undergo a secondary intraocular surgery and require cataract surgery;
• About to undergo a surgical procedure associated with a higher risk to corneal endothelium; e.g., phacoemulsification or refractive surgery;
• With evidence of posterior polymorphous dystrophy of the cornea or iridocorneal endothelium syndrome;
• About to be fitted with extended-wear contact lenses after intraocular surgery.

Medicare policy also states that, if corneal endothelial microscopy is performed as part of a workup before cataract extraction, that technique is not billable separately but is covered as part of the presurgical comprehensive eye examination and not in addition to it.

Therefore the above recommendation to consider corneal endothelial microscopy as part of the evaluation and management of the patient is an extension of existing Medicare policy.

References:

1. Cataract Management Guideline Panel. Cataract in Adults: Management of Functional Impairment. Rockville, MD. AHCPR Publication no. 93-0542, 1993.
2. American Academy of Ophthalmology. Corneal endothelial photography. Ophthalmology 1991; 98(9):1464–8.

Source:

A search of literature was completed through the MEDLINE database from January 1966 through June 1997. The search strategy focused on references containing the following words:

– Corneal dystrophy
 
– Corneal endothelial microscope
 
– Endothelial cell photography
 
– Specular microscope

Corneal endothelial microscopy
Endothelial photography
Microscopy, corneal endothelial
Specular microscopy