Harrison S. Weisinger

The role of docosahexaenoic acid in retinal function

An important role for docosahexaenoic acid (DHA) within the retina is suggested by its high levels and active conservation in this tissue. Animals raised on n-3-deficient diets have large reductions in retinal DHA levels that are associated with altered retinal function as assessed by the electroretinogram (ERG). Despite two decades of research in this field, little is known about the mechanisms underlying altered retinal function in n-3-deficient animals. The focus of this review is on recent research that has sought to elucidate the role of DHA in retinal function, particularly within the rod photoreceptor outer segments where DHA is found at its highest concentration. An overview is also given of human infant studies that have examined whether a neonatal dietary supply of DHA is required for the normal development of retinal function.

Management of patients undergoing hydroxychloroquine (Plaquenil) therapy.

The quinolines, hydroxychloroquine (Plaquenil) and chloroquine are used primarily for their anti‐inflammatory effects in the treatment of auto‐immune conditions such as rheumatoid arthritis. Another common use of these drugs is the prophylaxis and suppression of malaria. The use of quinolines may cause several ocular side‐effects. The most significant complication is irreversible macular damage resulting in both visual acuity and visual field loss. However, the Royal College of Ophthalmologists, UK (RCO) recently recommended against the monitoring of patients receiving quinoline therapy as it was deemed to be too costly, given the low incidence of retinal complications. In this article, we present a case of hydroxychloroquine retinopathy, describe the ocular changes associated with quinoline therapy and recommend an optometric review schedule for patients who are currently taking these drugs. Furthermore, we recommend a proactive approach toward medical practitioners prescribing these drugs for optometric‐based monitoring of these patients.

Neural Function Following Dietary n-3 Fatty Acid Depletion

It has been known for many years that mammalian brains are rich in lipid. In the early 1960s, shortly after the development of gas-liquid chromatography, it was reported that the human brain gray matter phospholipids contained a high proportion of polyunsaturated fatty acids (PUFA) (O’Brien and Sampson, 1965). Within a decade, it had been shown that the types and proportions of PUFA in the gray matter of 25 different mammalian species were very similar (Crawford and Sinclair, 1972; Sinclair, 1975; Crawford et al., 1976). In these studies, it was revealed that in all species the gray matter was rich in lipid (approx 40%) and that this was largely structural lipid (phospholipids and cholesterol). In all cases, six main fatty acids comprised the brain gray matter phospholipids, with three being PUFA, namely arachidonic acid ([AA] or 20:4 [n-6]), docosatetraenoic acid (22:4 [n-6]), and docosahexaenoic acid ([DHA] or 22: 6 [n-3]). These PUFA were present in a characteristic pattern in each species with AA, 22:4 (n-6), and DHA accounting for 12.0, 6.3, and 22.0% of phospholipid fatty acids, respectively (mean value for 25 species). Subsequent analyses of retinal fatty acids, from a smaller number of mammals, has shown that the retinal phospholipid fatty acids are also rich in PUFA, with DHA being the predominant fatty acid (Fliesler and Anderson, 1982). In contrast to the brain and retina, there is a diverse pattern of PUFA in the phospholipids of other tissues, such as liver and muscle, probably reflecting the wide differences in intake of essential fatty acids between species (Crawford et al., 1976).