A Tale of 2 Refractive Errors

President’s Message By Erin Swift, O.D.
A 41 year old African American male presents to your office with the chief complaint of sudden onset blurry distance vision OU x 1 week. The patient denies history of trauma, pain, floaters, or flashes of light. His medical history is significant for hyperlipidemia only (he is not currently on any medications) and his ocular history is unremarkable. He was seen ~2 months prior for a walk-in exam due to “bump” on eyelid OS, which was diagnosed as a hordeolum.

Otherwise, the examination showed the patient’s ocular health to be unremarkable OD & OS and he was emmetropic with unaided distance acuity of 20/20 OD and OS. At today’s exam, the patient reports the hordeolum resolved 2-3 weeks later (after using warm compresses) and has had no further problems until the blurry vision began one week ago. His entering uncorrected distance acuities today are 20/100 OD and OS (pinhole 20/20-1 OD, and 20/25 OS) and unaided near acuity is 20/20 OU. Refraction yields -1.00 sphere OD & OS with 20/20 vision OD & OS (binocularly balanced).

It is also noted that the patient’s vision was greatly reduced in both eyes with mild fogging during refraction.  Accommodative and binocular testing is largely unremarkable, consistent with early presbyopia.  The patient refuses dilation, but undilated fundus exam is unremarkable OD and OS.
So, what can it be?!  A few differential diagnoses for the myopic shift might include: early presbyopia or accommodative dysfunction, cataract formation, medication induced myopia, or undiagnosed diabetes mellitus.  While the patient (41 years old) is likely an early presbyope, a sudden myopic shift is atypical.  Additionally, accommodation and binocular vision were tested and deemed largely unremarkable.  Cataract formation can cause a myopic shift; however, also unusual in a 41 year old patient and undilated fundus exam showed clear lenses OU.  Many medications can cause vision and refractive error changes, including certain anticholinergics and antihypertensives, corticosteroids, and oral contraceptives.  According to the patient’s report, he has not started any new medication and is not currently taking any medication at all.  Therefore, undiagnosed diabetes is the most likely diagnosis.

So, what should you do?!  Since glucose testing is CLEA-waived, checking his blood glucose in office is a good option.  While it will most likely not be a fasting measurement, random glucose testing can still provide valuable information; there is big difference between 150 mg/dL and 500 mg/dL.  Another good alternative, if you have privileges with a local lab, is to order labs and send the patient for fasting glucose and HbA1c.  In cases where you are unable to order the necessary blood work, encouraging the patient to visit his/her PCP as soon as possible is the best course of action.  Working at a hospital, I am able to order lab testing and found out two days later this patient had a fasting glucose of 458 mg/dL and HbA1c of 12.7%.  Yikes! The patient was sent to the emergency department and started on IV fluids and insulin immediately (in titrated doses).  After the blood glucose was safely lowered, the patient was sent home with oral medication and a glucometer. I called him a week later and he reported the distance blur had resolved and he was seeing much better with blood glucose levels under 200 mg/dL.

I won’t bore you with the physiology of how glucose affects refractive error (and there are several theories), but it does happen and is relatively easy to diagnose.  Often blurred vision can be the presenting sign of hyperglycemia.  The American Diabetes Association estimates ~7 million people in the United States have undiagnosed diabetes and almost 80 million have pre-diabetes.  As primary eye care providers, it is important to understand that sudden refractive changes can signal underlying systemic conditions so that we may properly manage not only the ocular, but total health of our patients.  Prompt laboratory testing and co-management with primary care physicians is imperative.  Patient education is also crucial; not only on their general health, but also how systemic conditions affect their ocular health, spectacle correction, and vision