This seems like the age old question when it comes to selecting reading glasses. My opinion is that it really comes down to personal preference. While there are some specific differences, for me it is more about the differences in look and style.
Here are some key points when comparing plastic and metal reading glasses:
Plastic Reading Glasses
Plastic reading glasses are in general a little heavier than metal ones*. Also, the thicker frame usually hides a thicker lens better. This is important to remember when you start to get into the higher lens strengths of reading glasses, say +2.50 and higher. With the popularity of plastic frames, there seems to be more options for colours, shapes, and sizes. Plastic reading glasses also can easily create a look, especially a bold one, with today’s eyewear trends leaning to larger frames.
Metal Reading Glasses
Metal reading glasses are generally lighter than plastic ones*. The main advantage metal reading glasses have over plastic ones is that they can be easily adjusted to ones face, mainly because of the adjustable nose pads. Also, metal reading glasses usually have a more subtle and understated look to them, when compared to plastic reading glasses. One thing of note: if you like to put your reading glasses on your head when you are not wearing them (which is not good for any pair of reading glasses BTW), you can expect the nose pads of metal reading glasses to potentially get caught in your hair. I have witnessed hundreds of customers in the store not buying metal reading glasses based on this.
As I mentioned earlier, it really comes down to personal preference. I can’t really say which is better as both have their pros and cons. The one that is better is the one that makes you feel good when you are wearing it!
* To determine the weight comparison between metal and plastic reading glasses, I randomly selected 5 reading glasses in each category (all with the same lens strength) and determined an average weight. The results were that the average weight of a plastic reading glass was 30 grams as opposed to 26 grams for a metal.