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A3710 - Blinded by Science, Progressive Visual Impairment in a Patient with Retinitis Pigmentosa and Pulmonary Arterial Hypertension Treated with Tadalafil
Author Block: A. M. Vergis1, H. K. Bhatt2, R. H. Anguiano3, D. R. Fraidenburg4; 1Medicine, University of Illinois at Chicago, Chicago, IL, United States, 2Opthalmology, University of Illinois at Chicago, Chicago, IL, United States, 3Pharmacy, University of Illinois at Chicago, Chicago, IL, United States, 4Medicine, Division of Pulmonary, Critical Care, Sleep, and Allergy, University of Illinois at Chicago, Chicago, IL, United States.
Introduction: Pulmonary arterial hypertension and retinitis pigmentosa are both rare, difficult to treat, and progressive diseases. Interestingly, the therapy for one may have important consequences for the other. Tadalafil, a phosphodiesterase (PDE) type 5 inhibitor, is shown to have nonselective activity and can inhibit PDE6. Mutations in the gene encoding PDE6 are implicated as the cause of some cases of retinitis pigmentosa (RP). We present a case of a patient who developed signs of RP and had rapidly progressive vision loss while on tadalafil therapy for pulmonary artery hypertension.
Case: A 54 year old woman with scleroderma was diagnosed with pulmonary arterial hypertension in 2011 after developing exertional dyspnea and peripheral edema. After her workup was completed, she was started on tadalafil at 20 mg daily. She progressed to severe pulmonary hypertension but did not tolerate parenteral prostacyclin therapy. Her medical therapy was advanced to include an inhaled prostacyclin and an endothelin receptor antagonist. Tadalafil was advanced to 40 mg daily. In 2015 she was evaluated for cataract surgery and referred to a retinal specialist after noted scarring in her left eye. Specific ocular complaints were floaters, decreased night vision, and decreased visual acuity. A diagnosis of retinitis pigmentosa was made. She had no known family history of retinitis pigmentosa, but her father had lost vision in his left eye previously. She had poor follow-up and did not return to the retina specialist until 2017 after reporting continued progressive vision loss. The diagnosis of retinitis pigmentosa was then made apparent to the pulmonary hypertension clinic, her tadalafil was quickly transitioned to riociguat, and she is being monitored closely for progression of retinitis pigmentosa.
Discussion: RP is an inherited disorder characterized by progressive degeneration of the retina affecting 1 in 3000-7000 people. PDE6, found exclusively in the retina, is essential for visual phototransduction and mutations in the genes encoding PDE6 are the second most common identifiable cause of autosomal recessive RP. PDE5 inhibitors are shown to have nonspecific PDE inhibitory activity, with PDE6 sharing the greatest homology with PDE5. Mouse models carrying a diseased PDE6 gene and treated with sildenafil are shown to have rapid vision impairment which forms the basis of FDA labeling to avoid use of PDE5 inhibitors in patients with RP. While concurrent diagnosis of these conditions is rare, this is an important interaction which clinicians should be aware of which can have lasting effects on our patients.