Street Smarts

Dilation Variation

By Dan Beck, OD Leland, N.C.

No one I’ve ever met actually enjoys being dilated. Although there may be a few masochistic oddballs out there who enjoy the light show, dilation causes a brief, but very real burden on our patients. We dilate because that’s what we do. It’s what we were taught.

While there can be little doubt that dilation leads to a more thorough eye examination, how, when and how often we dilate varies greatly within our profession. When a record states that a dilated fundus exam was performed, all that really tells us is that some kind of drop was instilled in the patient’s eyes and some form of lens was used to look at the back of the eye. The real issue, therefore, isn’t whether a patient was dilated, but how much of the retina was actually seen.

Let’s compare two patients. Patient A is an 18-year-old mildly myopic female with blue eyes and no history of medical problems. Patient B is a 73-year-old male with dark brown eyes and a history of diabetes. Using the time-honored standard drops of 0.5% Tropicamide (Bausch + Lomb) and 2.5% Phenylephrine should give us the widest dilation for both patients. We all know, however, that Patient A will most likely have a dilation so wide that the iris will be barely visible. By contrast, Patient B’s pupils may only dilate a few millimeters. In addition, age-related lens changes in Patient B may make clear fundus viewing more difficult.

Patient A would almost certainly have dilated adequately with a much milder dilation agent such as Paremyd (Akorn Inc.), 0.5% Tropicamide, or possibly just 2.5% Phenylephrine alone. Our male patient, on the other hand, may require a second round of the stronger drops just to make peripheral viewing possible.

Another area of variation is the type of equipment used to perform the dilated fundus exam. Although the binocular indirect ophthalmoscope is the obvious standard of care, many doctors still dilate their patients only to limit the testing to views through a slit lamp. I even know a few doctors who dilate and only use a direct ophthalmoscope to look into the back of the eye with no real depth of focus appreciation.

To bring home the point, let’s say a binocular indirect ophthalmoscope was used to examine Patient A and a direct ophthalmoscope was used on Patient B. Both patients’ records will state that a dilated fundus examination was performed, yet there’s a vast difference in the amount of retina viewed. If a binocular direct ophthalmoscope with a small pupil aperture was used on our first patient, it’s possible more of the retina would have been seen than with the second patient, even if the first wasn’t dilated with drops.

While newer instruments such as the Optos ultra-wide camera can dramatically aid in our viewing and examination of the retina, this technology is too cost prohibitive for many optometrists. But there really is no excuse not to use the equipment we have in our offices. The direct ophthalmoscope has no place in a dilated fundus exam. Regular dilated, retinal evaluation with an adequate drop, a binocular indirect ophthalmoscope and a slit lamp-condensing lens will provide the best views and care. nOD