Anorexia and bulimia can do measurable and likely irreversible damage to women’s eyes, researchers in Greece have found.
In a small study whose results were published online in the British Journal of Ophthalmology, Marilita M. Moschos, Ph.D., and her colleagues at the University of Athens reported finding "a significant anatomical and functional impairment, marked by a decrease in macular and retinal nerve fiber layer thickness as well as a decrease in electrical activity in the macula," among women with a history of anorexia or bulimia.
"The good thing is that the [anorexic and bulimic subjects] still had good vision," Dr. Moschos said in an interview. "But there is a crucial moment where if they lose more photoreceptors – for example, with untreated disease – "this will cause an irreversible vision loss."
For their research, Dr. Moschos and her colleagues evaluated macular and retinal nerve fiber layer thickness, as well as the electrical activity of the macula, in 13 female patients (mean age 28.6 years) with a diagnosis of anorexia nervosa (AN) – either of the calorie-restricting (n = 6) or binge-purge (n = 7) type, along with 20 healthy controls matched for age. Anorexic and bulimic patients had been diagnosed at least 8 years prior to the study and were in treatment at the time of the study, without current marked vitamin deficiencies [Br. J. Ophthalmol. 2010 [doi 10.1136/bjo.2009.177899]).
None of the anorexic or control patients had evidence of any visual failure; visual acuity for all remained normal. What the researchers found was subclinical damage to the structure of the anorexic women’s eyes. The anorexic women saw a mean foveal thickness of 140.04 mcm, compared with 150.85 in the control group. Retinal nerve fiber layers were also thinner – 116.42 mcm – in the superior area (vs. 123.15 in the control group) and 121.08 mcm in the inferior area (compared with 137.6 in the control group) around the optic nerve. With patients who self-induced vomiting, the damage was worse: in the left eye only, the calorie-restricting anorexics had a better foveal thickness (median 142 mcm) than did bulimics (median 134 mcm).
"Our results show that the retinal thickness of the macula is higher in restrictive-type anorectic patients than in binge-purge type patients, which means that the anatomical impairment of the fovea is greater in the AN binge-purge type, Dr. Moschos and colleagues wrote."
The possible reason for this, said Dr. Moschos in an interview, is that while calorie-restricting anorexics manage to obtain some vitamins, women who purge absorb fewer. "My opinion is that there is a correlation to vitamin deficiencies" over prolonged periods, she said.
Dr. Moschos and her colleagues noted that deficiencies of vitamin A in particular, a presumed culprit in one case study they cited of an anorexic with retinal lesions (J. Fr. Ophtalmol. 2007;30:15), were not seen among their subjects, whose own ocular changes, they speculated, were either caused by deficiencies of other nutrients or occurred in relation to dopamine, "an important neurotransmitter in the visual pathway."
The resxearchers mentioned several previous studies examining dopamine and physical changes to the retina. In people with Parkinson’s disease, "where there is a reduction in dopamine in the retina," they wrote, changes to retinal structure and function have been observed (Invest. Ophthalmol. Vis. Sci. 1990;31:2473-5).
And documented instances of impairment in visual discrimination learning among anorexics (Appetite 2003;40:85e9) "may be related to decreased appetitive function, possibly resulting from impaired dopaminergic neurotransmission, either as a result of food restriction or, more intriguingly, related to the underlying pathophysiology of AN itself," Dr. Moschos and her colleagues wrote.
The investigators acknowledged the limitations posed by the small size of their study, which is ongoing. Now, the group is extending the study to seek longer-term evidence of decline or even recovery in the young women’s maculae following treatment for their anorexia or bulimia. Currently, Dr. Moschos said, the wisdom that macular damage is irreversible stems from the fact that "what we know about maculae concerns much older people," than the anorexics in the study.
The study was funded by the University of Athens. Dr. Moschos and her colleagues reported no conflicts of interest.