BLOG: Should OCT be mandatory before every cataract surgery?
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With reimbursement decreasing and the number and price of ophthalmic instruments ever increasing, all providers have to be conscious of limiting tests to those that reliably improve both patient care and outcomes.
Not long ago, the only additional test a cataract surgery patient received preoperatively beyond those in any complete ophthalmic examination was an A-scan ultrasound measurement of axial length. However, today there are a myriad of computerized instruments that are routinely employed in a surgical evaluation, including biometers (Lenstar, Haag-Streit; IOL Master, Zeiss) that precisely measure keratometry, anterior chamber depth, lens thickness and axial length.
Further, Scheimpflug anterior segment imaging (Pentacam, Oculus) detects subtle corneal features and diseases on both the front and back surface and is considered mandatory for the premium IOL candidate.
Macular OCT has been routinely performed on all patients wanting multifocal lenses. The reduced contrast sensitivity from multifocal IOL’s is typically unnoticeable in those with a healthy retina but can negatively impact vision function in patients with macular disease. Consequently, multifocal IOLs are avoided even in those with macula findings only detectable with OCT, particularly if there is any risk for progression.
Besides the multifocal candidate, macular OCT has usually been reserved for those with either a known history of macular or retinal disease or else after the clinical exam when a posterior segment problem has been discovered. In short, OCT has not been a routine test for every patient before cataract surgery. Should it be?
Retinal specialist Steve Charles, MD, has argued, “Yes.” We all are familiar with refractive surprise, a term that means a patient’s outcome refractive error is significantly different from what was planned and calculated. Charles coined a new term called visual surprise, meaning objective acuity or subjective dissatisfaction with vision that stems from a condition that was not detected until after surgery. He contends that macular OCT should be performed on every patient having cataract surgery regardless of the history of macular or retinal health or the results of the clinical exam with the goal of reducing visual surprise from macular disease only detectable by OCT.
First, some background. Until OCT became widely available, the steps for managing a visual outcome that was poorer than expected began with fluorescein angiography, looking for cystoid macular edema (CME). If that was normal, then a visual field was obtained, investigating for evidence of a prior retinal vascular event or preexisting glaucoma or neurological disease. When the visual field was not abnormal, the final test would be an MRI of the brain and orbit. Certainly, fluorescein angiography was vital in diagnosing CME that was difficult to detect clinically. However, the truth is that these expensive tests — particularly MRI — more often did not reveal any cause for poor visual acuity.
OCT, and spectral domain OCT in particular, changed all that. Looking back, it’s likely that many if not most of these cases of “poor vision of unknown cause” were due to preexisting macular conditions invisible to both our eyes and our instruments that modern OCT nearly flawlessly detects, such as vitreomacular traction, macular schisis and transparent epiretinal membranes.
Charles makes some practical arguments for mandatory OCT. First, patient expectations have never been higher for excellent vision after surgery. Any preexisting macular problem that was discovered only after surgery is a recipe for disappointment. Second, the doctor performing the preoperative examination typically does not have the skill or expertise to discover subtle retinal problems that a retinal specialist possesses. Third, OCT can discover problems that even the most highly skilled retina specialist may miss on the clinical exam. Finally, no matter the explanation, a patient is likely to blame the surgery for any vision outcome that is less than what was expected.
But perhaps the most compelling argument is simply this: if a test is quick, noninvasive and has a high likelihood of discovering a condition that may limit the outcome of a procedure, do we have a duty to perform it as part of informed consent? That is a legal argument we can’t answer. But as a moral argument, it’s hard to refute.
We began mandatory macular OCT at PCLI some time ago. And quite honestly, one of us (Alldredge) has been surprised at the proportion of previously unknown subtle macular abnormalities. Yes, most of these are inconsequential as far as outcome; a subtle epiretinal membrane is the most common. Still, it seems that a patient should know whether an easily detectable condition may limit his vision after surgery, even if it is not likely. In some diabetic patients with no detectable findings of retinopathy, we have found widespread thinning of the sensory retina that is impossible to see on the clinical exam. Whether this finding will have any impact on vision, we simply do not know.
Perhaps the greatest resistance in adopting routine preop OCT is that unless a billable pathology is discovered, then the test is either an out-of-pocket expense charged to the patient or else is performed at no cost. We have adopted to do the latter. Yes, it is normally a test that’s billed to the patient, but to avoid any patient resistance to something that can show a significant reason for a less than satisfactory outcome, it seems to be a small price to pay.
In short, we agree with Charles and argue that, yes, macular OCT should be mandatory before every surgery.
Reference:
Charles S. Video: OCT before cataract surgery should be standard of care. Healio.com. Posted June 1, 2018. Accessed December 4, 2020.