Both are in the realm of possibilities.
A number of individuals on this site have reported eye related issues they believe linked to the consumption of Propecia. There may be individuals that are highly susceptible to its possible effects on ones eyes.
http://www.propeciahelp.com/forum/viewtopic.php?t=2349&highlight=eyes
http://www.propeciahelp.com/forum/viewtopic.php?t=1157&highlight=eyes
http://www.propeciahelp.com/forum/viewtopic.php?t=662&highlight=eyes
In at least one study, finasteride 5 mg was associated with a small increased risk for developing a high-malignancy cancer. The reason for this small increased risk is not understood.
It should also be noted.
Research indicates that using the drug Propecia can alter the results of the prostate-specific antigen (PSA) test used to screen for prostate cancer in men.
A study done at the University of Texas Southwestern Medical Center, found that men on Propecia may have dangerously high PSA levels even if their test indicates levels are in the normal range.
The study found that Propecia cuts PSA levels in half after one year of use. While there is no PSA threshold below which cancer risk is completely eliminated, or above which cancer is a certainty, the conventional normal range is between 0 and 4.0. However, for men on Propecia, a PSA level of 2.0 could indicate prostate cancer risk.
If you’ve been on Propecia for a year, you should double the PSA score. If you are on Propecia for more than a year, don’t multiply the score, look at the change in PSA over time. If it goes up by more than three-tenths of a point, consider a biopsy,