Why It’s Important to Have an OCT in Your Practice

OCT is now commonly considered the standard of care for the detection and monitoring of various ocular diseases across optometry and ophthalmology literature.^1-4 In fact, according to one source, between 80% and 85% of optometrists say they have an OCT in their practice.⁵ OCT imaging can be used to monitor whether glaucomatous changes are new or continuing despite treatment, to assess severity and progression versus resolution of macular edema, and to assist in screening for development of neovascularization in macular diseases, in addition to a whole host of other uses.

THE CASE FOR OCT

For years before the advent of OCT, eye examinations alone sufficed, so is OCT really necessary? Absolutely! (At least until someone invents a wearable device that eye doctors can use to measure a patient’s eye tissue on the spot during a fundus exam. Let’s get to work, Silicone Valley!)

I tell patients that OCT takes microscopic, quantitative measurements of their ocular tissue that allow me to discern differences from year to year that I would not be able to observe using only my eyes. With reliable, quality OCT scans, a decrease of at least 5 µm in average retinal nerve fiber layer thickness and/or a decrease of at least 7 µm to 8 µm in a sector of retinal nerve fiber layer thickness is suggestive of glaucomatous progression.⁶ A measurement of 5 µm equates to about 0.0002 of an inch, or the diameter of a red blood cell. Recent data suggest that monitoring suspicious optic nerves to detect significant change in a timely manner may require more frequent OCT scans than previously thought, especially for rapid progression.⁷

Although I love noting and remembering fun facts about my patients, I’ll never be able to tell (on my own) that their retinal nerve fiber layer looks one red blood cell diameter thinner than the last time I examined them. Without this and other quantitative capabilities of OCT, diseases have a stronger potential to go undetected, undiagnosed, and untreated for years before intervention could have stopped pathology in its tracks. Earlier disease detection decreases the need for more advanced invasive treatment down the road, thus decreasing the chances that any of our patients would ultimately lose enough vision to limit their quality of life.

OCT LIMITATIONS

Although a doctor’s eyes are not always enough to assess disease progression on their own, it should be mentioned that a machine is also not sufficient to assess disease progression by itself, either. For instance, an OCT of the macula showing subclinical macular edema doesn’t tell me why it’s there, and an OCT of a truly stable optic nerve can look different from year to year based on scan quality.

In training, we were often reminded to beware of red disease—findings on a scan that may be flagged as abnormal or progressive in the absence of true pathology. A guided progression analysis, for example, might highlight a column of measurements to alert me that one aspect of my patient’s optic nerve has thinned dramatically from their baseline testing. However, upon closer analysis, I might discover that this finding arose from the optic nerve being mapped with a variable disc margin—varying slightly in tilt or overall area from year to year—or that the big-picture analysis was affected by an artifact or poor-quality scan that hasn’t been deleted from the dataset (Figure). Ultimately, there is no replacement for a doctor’s judgment in deciding whether something is wrong with a patient, what that something is, and what needs to be done about it.

Aside from these limitations, potential barriers to introducing OCT to an eye care practice include financing costs, physical footprint, staffing, and reimbursement. (Read Considering Investing in an OCT? for some food for thought.)

OCT: THE ACE UP YOUR SLEEVE

I’m fortunate to have had access to an OCT in every setting I have trained or practiced in—Veterans Affairs hospitals, university clinics, MD-OD settings, and private optometry practices. Having immediate access to an OCT allows me to make more confident assessments of the state of my patients’ ocular diseases and dramatically decreases the number of patients I would otherwise refer to an outside practice. I strive to reserve referrals to other eye care providers for services that I cannot provide, as subspecialty consults should be saved for patients who need them most.

In my OD-MD practice setting, I primarily reserve my glaucoma referrals to our in-house glaucoma surgeon for patients who would benefit from laser or surgical intervention. After a procedure is performed, or if an advanced glaucoma case is no longer a candidate for surgical intervention, our surgeon will refer these patients back to me (or to the outside referring OD, if they are equipped to monitor glaucoma) for continued monitoring with OCT/visual fields and topical therapy management. This cuts down on the vast majority of patient volume they would otherwise need to see and frees up their schedule for time-sensitive surgical consults, which can, even in this collegial comanaged system, often book out 3 to 4 months or more.

THE DIAGNOSTIC DEVICE YOU DON’T WANT TO BE WITHOUT

As the need for medical eye care increases without a corresponding rise in the number of ophthalmologists, it will become more important for optometrists to provide the best, most comprehensive medical eye care possible under their own roofs. Expanding the capacity of care that every eye doctor provides will, in turn, increase the general public’s access to care. An OCT not only adds value to your practice’s financial statement, but also to your ability to provide the best possible care as an optometric physician.

As an aside, adding an OCT may understandably not be a top priority for certain specialties in optometry, such as pediatric vision therapy. Likewise, I haven’t equipped my practice with all the bells and whistles of vision therapy. However, a comprehensive eye care practice is well-positioned to add OCT testing to its clinical flow.