Choroidal atrophy in a patient with paraneoplastic retinopathy and anti-TRPM1 antibody
A 69-year-old man visited our clinic in July 2010 with complaints of blurred vision and night blindness in both eyes. Our initial examination found that his best-corrected visual acuity in decimal units was 1.0 in the right eye and 0.6 in the left eye. His refractive error was +3.0 D and +3.5 D for the right eye and left eye, respectively. Full-field rod ERGs were absent and cone-rod mixed responses were the negative type, indicating ON bipolar cell dysfunction (). From the symptoms and ophthalmic examination, he was suspected of having PR.\nA general physical examination revealed small cell carcinoma of the lung and Western blot of the patient’s serum showed autoantibodies against TRPM1. We diagnosed this patient with melanoma-associated retinopathy and retinal ON bipolar dysfunction due to TRPM1 autoantibody and have reported his findings in more detail elsewhere. After diagnosis, chemotherapy was started using cisplatin and etoposide combined with radiation for the lung cancer in August 2010. The patient achieved a complete remission, but underwent cranial irradiation in March 2011 to prevent brain metastasis.\nWe have followed this patient ophthalmologically for more than 2 years since his initial visit and his symptoms have not changed. His best-corrected visual acuity decreased slightly to 0.8 in the right eye and 0.5 in the left eye due to progression of cataracts. His visual field has not constricted and his ERGs have not changed (see ). Rod responses were nonrecordable in 2010 and 2012. The amplitudes for a-wave of cone-rod mixed maximum response were 240 μV and 220 μV in 2010 and 2012, respectively, and those for b-wave were 150 μV and 120 μV, respectively. The amplitudes of cone response were about 25 μV for the a-wave and 50 μV for the b-wave at both times in 2010 and 2012. The amplitudes of the 30 Hz flicker ERGs were 14 μV in 2010 and 11 μV in 2012. The difference in the ERGs was most likely within the error of measurement and not due to differences in retinal function. However, fundus photographs taken in October 2012 showed diffuse choroidal hypopigmentation in both eyes (). We also found that the choroidal vessels were more visible than those obtained at the initial examination ().\nSpectral domain optical coherence tomography (Heidelberg Engineering, Heidelberg, Germany) showed a slight reduction in retinal thickness during the 2 years of follow-up, but the morphological architecture of the retina appeared almost normal at both times (). Consistent with the choroidal hypopigmentation of the fundus, spectral domain optical coherence tomography showed a marked decrease in choroidal thickness over the 2-year period (, arrowhead). Subfoveal choroidal thickness in the right eye measured manually was 250 μm in 2010, 180 μm in 2011, and 110 μm in 2012, and for the left eye was 380 μm in 2010, 230 μm in 2011, and 100 μm in 2012.