This case involves a middle-aged male patient who was on chloroquine for treatment of extraintestinal amebiasis for several years. He subsequently presented to his optometrist for changes in his vision. He was diagnosed with ocular migraines, which he was told are harmless and typically self-resolve without medication. Over the course of the next several months, the patient experienced worsening vision. He returned to his optometrist and was diagnosed with bullseye maculopathy and nearly full blindness. An expert in optometry was sought to review the type and quality of the assessment performed in light of the patient’s medical history.
Question(s) For Expert Witness
- 1. What is the standard testing for someone on long-term chloroquine with changes in her vision and headaches?
Expert Witness Response E-133701
For my patients taking cholorquine, I follow the guidelines as set out by the American Academy of Ophthalmology published in 2002 and revised in 2011 and again in 2016. The risk of toxicity associated with chloroquine is affected by the dosage that the patient is taking and the number of years they have been on the drug. During case history, I would try to determine the cumulative dosage of the drug that the patient would have taken This would be the number of days taking the drug multiplied by the dosage. For patients new to therapy, a baseline examination is performed which includes a 10 – 2 automated visual field, fundus examination and one of three tests (SD-OCT, FAF, mfERG). Annual screening for cholorquine toxicity would then begin after 5 years and every year after. The risk of toxicity is approximately 1% at 5 years, 2% up to 10 years but increases sharply to almost 20% after 20 years. The single biggest risk factor for developing vision loss would be the number of years the patient is taking the drug. When patients present with a complaint of headaches a full comprehensive eye examination is required. To arrive at a diagnosis of a headache/migraine is a diagnosis of exclusion. A detailed history is required to inquire about the frequency, onset, region, and duration of the headaches. An evaluation of the refractive and binocular systems is required to determine if eye strain is a contributing factor. A thorough ocular health examination is also needed to rule out any pathology that may be a contributing factor.