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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 densitiescan 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 in order to measure and record endothelial cell counts of the cornea. This technique is also known as corneal endothelial microscopy. Images of the endothelium seen with specular microscopy can be recorded on video tape or photographic film in order to facilitate estimates 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 for 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 is considered medically necessary under the following conditions:

• As a pre-operative test for intra-ocular surgery (e.g., cataract surgery) in order to identify patients at risk for post-surgical corneal decompensation;
• In the diagnosis and management of patients with corneal dystrophies or other corneal abnormalities;
• With slit lamp evidence of endothelial dystrophy;
• With slit lamp evidence of corneal edema;
• About to undergo a secondary intra-ocular 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 irido corneal endothelium syndrome

None

The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.

8/1997: Revised; addition of medically necessary clinical indications approved by MPAC

4/18/2002: Type of Service and Place of Service deleted

4/24/2002: Code Reference section updated

10/27/2005:  CPT codes 92002-92014 deleted effective 12/8/2004; ICD9 procedure codes 95.09, V72.1, V72.83 deleted effective 12/8/2004;  ICD9 diagnosis code ranges 366.00-366.9, 371.20-371.24, 371.50-371.58 listed separately not in ranges.  ICD9 diagnosis code ranges 371.00-371.05, 371.10-371.16, 371.30-371.33, 371.40-371.49, 743.30-743.34 added.

2//7/2006:  Code Reference table updated, code 92285 deleted

10/10/2006: Policy reviewed, no changes

Cataract Management Guideline Panel. Cataract in Adults: Management of Functional Impairment. Rockville, MD. AHCPR Publication No. 93-0542, 1993.

Hayes Medical Technology Directory

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

Blue Cross Blue Shield association policy #9.03.04

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