This is a really interesting question, and from personal experience, I would have to say yes. Granted, it does matter what exactly you're watching on tv/doing on your computer,and for how long, but generally I would have to argue that if you are vibrating at a higher frequency than the frequencies these electronics are emitting (which seems likely as you were having visions, associated with the third eye) that these things could be lowering your frequency and causing your visions to stop happening. Televisions, phones, computers, and other electronics (including microwaves if you can believe it) have the ability to force you to "tune in" to the frequency at which they are vibrating. If you're focusing your energy on a television screen, you will absorb that energy in the same way you would with a crystal to aid you in raising your frequency. Televisions and phones, especially, are frequently used as means of "mind control" or by means of altering viewers' moods if you want to get more technical. This is done through news channels and scripted programming. Subliminal messaging plays a part in this. I would also like to say that if you are learning something, if you are opening your mind to something, it may not be decreasing your frequency as much, For example, if you're watching a documentary on crystals, you may find that the knowledge you're absorbing is energizing you rather than depleting your energy. Be mindful of what media you are absorbing and try to increase your knowledge and learn something. There are many resources such as research papers and articles online to support this conclusion, and I recommend that you watch a documentary or read up on the subject to gain a better understanding of it. To put it simply, they are most likely affecting your frequency by lowering it. The fact that you even felt the need to ask this question just goes to prove that you have already acknowledged this truth ! Listen to your higher self, or intuition, and you'll be surprised what you will find.
And, if you want to disregard everything I've just told you because it seems outlandish or unfamiliar, decrease your use of televisions and computers, or stop using them altogether and see what happens. Ground yourself, meditate, do whatever you think will help you raise your vibration. Good luck to you! Blessed be, love and light