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Allison L. Dorfman, Anton Malienko, Mathieu Gauvin, John M. Little, Pablo Cervantes, Pierre Lachapelle; Bringing light to bipolar disorder: peering through the window to the brain. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5026.
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© ARVO (1962-2015); The Authors (2016-present)
Bipolar disorder is a chronic psychiatric illness where neurotransmitter systems also known to play a role in retinal function are affected, albeit the mechanisms involved are largely unknown. The purpose of this study was to explore retinal function in bipolar disorder with the goal of identifying potential biomarkers specific to the disease.
Patients diagnosed with bipolar I and II disorder [supported by a Structured Clinical Interview (SCID-1) for DSM-IV-TR; n=23] were recruited and compared to control (n=12). Exclusion criteria included known retinopathy, required inpatient psychiatric treatment, current manic phase of the disorder, history of substance abuse in the past 6 months, light therapy and Parkinson’s disease. ISCEV standard photopic and scotopic ERGs were recorded using Espion V6.0.54 (Diagnosys LLC). DTL electrodes were placed in the conjunctival sac with reference and ground electrodes on the external canthi and forehead, respectively. DWT analysis was subsequently performed.
Photopic hills of bipolar and control groups revealed no amplitude differences (p>0.05), though peak time delays were observed at the peak (32.89±1.7ms vs. 30±1.1ms in control; p<0.05) and beyond. Segregation of recordings collected during euthymia, hypomania and depression phases revealed greater photopic a- and b-waves in the depressive (29.03±3.0 and 116.4±8.1µV) vs. euthymic (21.5±1.3 and 87.8±3.7µV; p<0.05) state. The rod b-wave was attenuated in euthymia compared to control (84.1±7.1 vs. 124.8±11.1µV; p<0.05). DWT showed several time-frequency anomalies, namely a reduction of the %OPs (46.6±2.7 vs. 55.5±4.7 in controls; p<0.05). This was explained by an attenuation of the 80 and 160 Hz energy (OPs descriptors) to 62% of controls (p<0.05), while the 20 and 40 Hz energy (b-wave descriptors) was unaffected.
ERG abnormalities are most notable when assessed as a function of the bipolar disorder phase and DWT revealed characteristics unique to the bipolar cohort. While it is well known that bipolar disorder is a complex multifactorial process, we believe that our results shed some light on the retinal function profile and could be trait markers in affected patients. Future studies aimed at further elucidating the latter are warranted.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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