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Viagra turns 20 in the United States 1:16
(CNN) - When a 31-year-old man entered the Eye and Ear emergency room at the Mount Sinai Clinic in New York, he had been seeing red for weeks.
His vision was literally dyed red, and he started after taking a seemingly high dose of a popular erectile dysfunction (ED) medication.
Blurred vision and sensitivity to light is a side effect of erectile dysfunction medications, but the symptoms usually resolve within five to 24 hours.
The man continued to see everything in shades of red for at least a year.
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"The last time we saw him, his vision improved, but he definitely showed some permanent damage to his vision," said ophthalmologist Richard Rosen, who heads the vitreoretinal surgery and research unit at Mount Sinai clinic.
Rosen and his team at Mount Sinai published a case report on the history of man in 2018. It was the first time, said Rosen, that researchers, using state-of-the-art technology, were able to see microscopic lesions in the cones of the retina, cells They are responsible for color vision.
His eyes turned blue
A new case series published on Friday tells the story of a dozen men who took sildenafil (generic Viagra) for the first time. Everyone arrived at the World Eye Hospital in Adana, Turkey, complaining of having "a very intense blue vision with red-green color blindness."
Why did these men see blue and not red? It has to do with the way the medicine affected the rods and cones of the eye, which are the photoreceptor cells of the retina located in the back of the eye.
"Due to the dysfunction of the bar cone, we can see a violet or blue color at the beginning," said ophthalmologist Cüneyt Karaarslan, lead author of the publication in Frontiers of Neurology. "If it progresses, this color turns yellow, orange or red."
Fortunately, he added, none of the men treated at the clinic progressed to that advanced state.
Enzymes and genetics
How might medications designed to improve penile performance affect the eye in this way?
All erectile dysfunction medications operate in the same smooth and automatic muscles of the body to improve blood flow. To do this, the active ingredient in the medicine inhibits an enzyme called phosphodiesterase 5 (PDE5) that is found in the walls of blood vessels. When it is blocked, the blood vessel walls relax and blood flow increases.
The eye contains a sister enzyme called PDE6 that plays a key role in the conversion of light within the rods and cones of the eye. The rods help us see at low light levels, while the cones work at higher light levels and help us see the color.
It turns out that PDE5 can also affect PDE6, which affects the eye cones and the ability to see color.
"Nobody knows exactly how this happens, we just know that there is a crossing," Rosen said. "Everyone has slightly different compliments of their red, blue and green cones, and depending on which of your cones are more sensitive, you may experience a change in vision."
There may be a genetic advocate for this too. If a man has a hereditary retinal disease, such as retinitis pigmentosa, Rosen said, he may have a higher risk of vision changes. Retinitis pigmentosa is a group of rare genetic disorders that create a collapse and loss of cells in the retina.
"If one of the genes is defective and then deactivates one with the medication, there is a possibility that it has more permanent damage," Rosen said.
Rosen speculates that a genetic problem may have contributed to why his patient saw red for more than a year. Unfortunately, Rosen was unable to do a genetic test in man and has not returned to the clinic for long-term follow-up.
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It's the dose, boys
However, the main cause of man's vision change is the extremely high dose of a liquid medication that he bought online under the brand name Viagra.
"We think it probably took in the range of maybe 300 or 400 milligrams," Rosen said. "The most reasonable people would not take [the equivalent of] seven or eight pills the first time they start."
An initial dose of Viagra, according to the manufacturer's website, is usually 25 or 50 milligrams once a day, with a maximum dose of 100 milligrams.
Interestingly, Turkish men with blue vision took the highest dose, 100 milligrams, in their first use.
That is definitely not the way it should be done, Rosen said. A man should work with his doctor to determine the smallest effective dose.
"Some people are very, very sensitive to small doses and others are insensitive," he said. “It's like assuming everyone wears the same size underwear; It doesn't work at all, right? But human nature is that if a little is good, you know, a lot has to be better. ”
While certain brands are supposed to work a little faster than others, experts say that none of the medications create a rapid erection and probably need sexual stimulation to work.
In addition to vision problems, there are serious side effects for all ED medications, especially if the man has an existing heart, kidney or liver disease, is taking a vasodilator that contains nitrates, or if the patient has low blood pressure or high uncontrolled.
"If you are going to take one of these medications, you start with a minimum dose," Rosen said. "See how he responds, and that he is not having any adverse effects, before jumping to the highest potential dose that is considered safe."
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