Sildenafil and Cyanopsia

Q: Sildenafil causes Cyanopsia because?

A) Trade brand Viagra is colored blue
B) It only occurs with Sildenafil
C) It sensitizes the retinal rod cells
D) It is a sign of underlying cataract
E) If it occurs, it should not be used in pulmonary hypertension


Answer: C

Sildenafil and other Phosphodiesterase-5 (PDE5) Inhibitors have become an integral part of pulmonary hypertension and has been used in ICU with increased frequency. The eye's lens has a yellow natural tint and it reduces the intensity of blue light before it reaches the retina. PD5-inhibitors decrease the enzymatic activity, sensitize the rod cells of the retina and enhanced its activity causing bluish tint in the vision.

Although infamously viagra is called blue pill, its color has nothing to do with bluish tint of vision (choice A).

All PD-5- Inhibitors can cause this effect (choice B).

Actually, bluish tint in the vision is a post-cataract surgery effect due to loss of naturally present yellow tint lens or with the artificially instilled clear lens (choice D).

It is usually a benign effect and should not stop clinicians from utilizing its potent advantage in pulmonary hypertension (choice E).

#pharmacology
#pulmonary



References:

1. Laties A, Zrenner E. - Viagra (sildenafil citrate) and ophthalmology.  Prog Retin Eye Res. 2002 Sep;21(5):485-506. 

 2. Hayashi, K., & Hayashi, H. (2006). Visual function in patients with yellow tinted intraocular lenses compared with vision in patients with non-tinted intraocular lenses. British Journal of Ophthalmology, 90, 1019-1023.