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BLOG: What is standardized testing before cataract surgery?
Why corneal topography and macular OCT have become essential parts of the cataract work-up
I would like to underscore the value of two established diagnostic tools to improve surgical results that most of us have had in our office for years: corneal topography and macular OCT.
In the era of modern lens implants, the standard of care has been the use of preoperative testing for corneal curvature as well as axial length measurement — initially by contact and later by immersion ultrasound biometry. These measurements help us assess what lens implant power will achieve the desired spherical outcome. About 15 to 20 years ago, optical biometry (Carl Zeiss Meditec IOLMaster and now Haag-Streit Lenstar) gained widespread acceptance because it improved the accuracy of results. More recently, use of corneal topography and macular OCT has become very valuable.
Corneal topography helps identify the degree of corneal astigmatism, and some imaging systems claim also to measure posterior corneal curvature. These are also helpful in identifying irregular astigmatism caused by forme fruste keratoconus, pellucid marginal degeneration and prior scarring. Topography helps identify when a toric lens might be helpful and when irregularity is so great that it might not. It also helps identify patients with tear film abnormalities caused by dry eye or basement membrane dystrophy; an irregular power map implies inaccuracy of biometry.
Macular OCT scanning can identify epiretinal membranes, early macular holes, vitreomacular traction and other subtle fundus pathology that can be virtually undetectable through fundus exam alone, especially when viewing through a dense cataract. Without this tool to warn me in advance, many of my own patients would be disappointed at the postoperative surprise of previously unknown maculopathy.
Who pays for these tests? According to reimbursement expert Kevin Corcoran, a physician cannot bill for a screening diagnostic test when no pathology is suspected on exam. Some physicians routinely perform and bill for these tests as part of an “advanced diagnostics package” offered to preoperative patients.
In my practice, for several years, we have been routinely performing topography and macular OCT tests on all patients before cataract surgery. In those with premium implants, the cost is included in the package price. In those choosing simply a monofocal lens with no astigmatic correction, it is a value-added service we perform at no charge.
Whatever the financial model, these tests clearly have value for patients’ preoperative evaluation, and as with continued refinement of our surgical results, I believe they will become standard of care.
Disclosure: Hovanesian has no relevant financial disclosures.