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Message: <blockquote data-quote="Binastro" data-source="post: 3220861" data-attributes="member: 111403">. Using averted vision, if one is experienced, it is possible to see that different areas of the field are brighter than others. In other words, it is possible to see fainter stars and fainter deep sky objects at certain positions in the field. I used to use this to maximise what I could see. However, I would not have thought that birdwatchers would experience this, although I suppose they might.Initially, I was wondering if small cataracts could be part of the problem, but only a careful eye examination would confirm whether this is the case or not.Even the most experienced observer, without the necessary testing equipment, will not be able to test their own eyesight as well as they could with the help of an experienced ophthalmologist.My eyesight tests take about 2 1/2 hours in total. This is necessary, at least for me, because I'm older and want to get the best performance from my eyes. With the correct prescription eyeglasses my resolution is about 130% better than the so-called 20/20 or 6/6 perfect eyesight. In fact, many people do much better than this, with some achieving 250% better. On the other hand, many people do not achieve 20/20 vision, but they still do very well. There is a vast range of eyesight abilities and one has to make the best of what one has.In my case, my optician for some reason enjoys testing my eyesight, which is why he is prepared to spend 2 1/2 hours. He says that I am the only person in his 30 years of testing, with whom he uses his one eighth dioptre lens. In other words I can focus to plus or minus one 16th of dioptre when I'm rested. And also fix the small amount of astigmatism to plus or minus 1.25°. Without glasses my resolution is quite low, so I need to use glasses generally, although even now if I am not doing anything special I don't wear glasses.It is no surprise to me that somebody in their 40s should choose to have a thorough eye examination. I started using glasses in my late 40s. At this time I found that my driving was affected by my eyesight in subtle ways, which had not occurred when I was younger.Eyesight examinations are important not just for ones eyes, but also for one's general health.</blockquote>

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