The specific type of vision loss, called non arteritic anterior ischemic optic neuropathy (NAION), occurs when blood flow to the optic nerve is blocked. It causes sudden and painless loss of vision in one or both eyes. Those who experience it in one eye are at a greater risk of experiencing a second time, affecting the other eye.

Vision loss may be partial or complete. While in some cases the condition may improve over time, it can also be irreversible. Studies suggest that the drugs like Cialis or Viagra may reduce the blood flow to the anterior optic nerve, resulting in tissue damage. Cialis and Viagra drugs may heighten the risk of NAION in those with vascular disease, who are already more susceptible. Risk factors for NAION include:

- age greater than 50 years

- heart disease

- high blood pressure

- high cholesterol

- diabetes

- smoking

- certain pre-existing eye problems

Healthcare professionals prescribing these drugs like Cialis and Viagra should warn patients of the potential risk. NAION is the most common form of optic nerve damage in older US adults, with up to 6000 people developing the condition every year. One in four has the chances that they will develop it in both the eyes.

Any patient who has endured a sudden severe loss of vision, and is prescribed Viagra or Cialis, should inform their healthcare practitioner first.

FDA also advises patients to stop taking these medicines, and call a doctor or healthcare provider right away if they experience sudden or decreased vision loss in one or both eyes. Health officials in Canada too have been advising individuals who use drugs Viagra, Cialis and Levitra to consult their physicians and seek immediate medical attention if they experience sudden vision loss or vision-related problems while taking these drugs.

FDA also has approved and asked pharmaceutical companies manufacturing Cialis, Viagra and Levitra to update their labels so that the customer knows of all the side effects.

Cialis is available online with various sites and one can online. There are many Cialis pharmacy which sells generic versions of Cialis online. Before buying from any of these , one must ensure that they are certified by the VIPPS. It is strongly recommended to buy Cialis only after proper consultation from the doctor and from certified online pharmacies and not just buy because is available on a particular online pharmacy which may not be certified. Cialis is an effective treatment for erectile dysfunction and should be taken an hour before sexual intercourse.