November 14, 2017
4 min read

OCT screening in internal medicine increases disease detection

A trained technician can administer the test, and the results could foster comanagement.

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It is no surprise that patients without a significant refractive error may wait until their 50s or even 60s before obtaining a comprehensive eye exam. Presbyopia in an emmetrope in some cases is a curse because it can be treated with store-bought reading glasses for decades.

Jerome Sherman

Some of the top glaucoma specialists in both optometry and ophthalmology now recommend optical coherence tomography screenings on everyone beginning at age 40.

Glaucoma specialist George Cioffi, MD, chairman of the department of ophthalmology at Columbia University in New York, stated at the SUNY Glaucoma Symposium earlier this year that he supports such OCT screening in order to detect retinal nerve fiber layer (RNFL) and ganglion cell abnormalities decades before symptoms. The majority of patients will pass the screening, but the quantitative data obtained should be used as a baseline for future scans.

Several of us decided to obtain OCT screenings on as many patients as possible in the medical complex of 10 MDs in internal medicine in Manhattan. Predictably, a lot of patients turn down the offer of a free 3-minute screening for retinal and optic nerve disorders, but many are willing to participate. At the present time, the MDs rarely insist on the screening for their patients, but once they better understand their value, this may change.

The OCT used for this project was the Optovue iScan, which can be administered by any nonophthalmic technician with about 15 minutes of instruction. The iScan can be run in an automated fashion, with the device talking to the patient and giving instructions: Close both eyes, open your eyes and look at the red dot, now look at the blue target to your left, test complete, etc.

The device has no joy stick, which is ideal for nonophthalmic technicians. Many of us still remember how difficult it was in optometry school to learn how to use a slit lamp biomicroscope because of the joy stick.

The specific program that we use is called iWellness. Previously, we published results using this program and demonstrated both sensitivity and specificity to be well over 90% in an Institutional Review Board-approved study performed at SUNY State College of Optometry (Awad et al.).

Case study

Fortuitously, one of the first patients we scanned was a 69-year-old female who, several months earlier, had a routine cataract extraction with a posterior chamber IOL in her left eye only. She was still under the care of the doctors and facility where the operation took place. She had no symptoms in her left eye and reported 20/20 visual acuity in an exam just 3 weeks earlier. Unlike other patients in the practice, she was not on her lunch hour and agreed to be screened.

Optic nerve head (ONH) and GCC of the patient’s right eye (top left) and left eye (bottom left). Although the GCC and ONH (RNFL) are normal or near normal in the right eye, both are markedly abnormal in the left eye. The GCC and RNFL in the left eye are most abnormal (attenuated) inferotemporally. The Summary Parameters (top right) reveal the dramatic difference between the eyes.
Source: Jerome Sherman, OD, FAAO

Surprisingly, the iWellness test revealed marked ganglion cell loss inferiorly in the left eye only. Obviously, the patient failed the screening and she was referred to the doctors at the surgical center. The OCT was repeated and revealed the same abnormal ganglion cell complex (GCC) in her left eye with corresponding RNFL loss.

Visual fields demonstrated a corresponding superior nasal step in the left eye only. A review of her chart documented some mild IOP elevation the week after the surgery. Several pressure measurements were in the mid- to upper-twenties, and mild corneal edema was noted, both common encounters after cataract removal.

She was treated with glaucoma drops and, within 2 weeks, her pressures were in the low teens, first with medication and then without medication.

Her doctors never bothered to do OCT and fields after surgery because there was no reason to do so. The patient has IOPs without medication in the low teens now, but the RNFL, ganglion cell and visual field abnormalities have been repeatedly documented. There is increasing evidence that corneal edema can mask much higher pressures. For example, William Wiley, MD, at the Cleveland Clinic, contributed a case of corneal edema and angle closure glaucoma with Goldmann IOPs of 14 mm Hg, but 46 mm Hg when corrected for abnormal corneal properties.

Diamox (acetazolamide, Duramed) will be used at the time of a future cataract extraction in the right eye as a precaution, and the Ocular Response Analyzer (Reichert), which measures and corrects for corneal hysteresis, will be used before and after surgery to document a more accurate IOP, a pressure measurement that is not influenced by corneal edema.

The patient’s thirty-degree threshold fields were obtained after the GCC and RNFL were demonstrated to be abnormal with the OCT. The superior nasal visual field loss in the left eye is predictable from the inferior temporal thinning of the GCC and RNFL. The fields in the right eye (not shown) were normal.

Useful for glaucoma, retinal disorders

If the use of the iWellness scan can detect glaucoma for the first time in a patient already under ophthalmic care, it is obvious it can detect glaucoma in many other patients who are not under such care. In addition to detecting optic nerve disorders, the device can detect numerous retinal disorders. For example, we have seen white dots in the outer plexiform layer, a common finding of exudates in diabetes (Awad et al.).

We are expanding the study, and may offer select patients an incentive to take part, such as a Starbucks voucher. We have already demonstrated that OCT screening in such practices will detect abnormalities not known to the group of internal medicine doctors. Both the scan and the interpretation of the scan can be taught in about an hour to novice observers (Slotnick et al.).

But what does the internist do with failures? Two logical approaches have been utilized.

First, have an optometrist in the office for a day or so a week to evaluate the patients who fail. Of course, some equipment such as a biomicroscope, an ophthalmoscope and a tonometer would be needed. The second approach, far simpler to implement, is to develop a referral relationship with a nearby eye care facility. This could be advantageous to both groups if referrals in both directions result.

Disclosures: Sherman has lectured for, received honorarium from or consulted with Arctic Dx, Annidis, Carl Zeiss Meditec, DGH, Diopsys, Eye Solutions, Heidelberg, MacuHealth, Optos, Optovue, PHP, Quantel and Topcon.