These days more and more people have vision problems, partly because of daily stress and the constant use of screens. The go-to way of correcting them is still a good pair of prescription glasses. People with a strong prescription reach for their glasses the moment they wake up: they simply cannot do without them, because without them everything is a blur. Nobody needs to explain to them how important their glasses are. To help you choose the most comfortable prescription glasses, especially if your prescription is high, it is worth spending a few minutes reading this article.
The four factors that decide how thick your lenses will be
When choosing prescription glasses, the biggest concern for people with a high prescription is the thickness and weight of the lenses. Broadly speaking, four factors affect how thick your lenses will be: the size of the frame, the lens index, the strength of your prescription and your PD (pupillary distance).
1. Prescription strength and frame size
As a general rule, the stronger your prescription, the thicker your lenses. With short-sighted (minus) prescriptions the lens is thicker at the edges; with long-sighted (plus) prescriptions it is thicker in the centre. Choosing the smallest frame that suits you will give you a much better look than a large frame: with minus lenses, the thickest part of the edge is cut away when the lens is edged in the lab, and with plus lenses the centre thickness can be reduced because a smaller lens diameter is needed.
2. Lens index
The lens index is another key factor in lens thickness. High-index lenses are a real step forward in terms of thickness and weight, with no loss of optical quality. As a guide, a 1.67 high-index lens can be up to around 35% thinner than a standard CR-39 lens (index 1.50) for the same prescription, and a 1.74 lens is thinner still. You can read more in our guide to thinner lenses for high prescriptions.
For long-sighted prescriptions it is also a good idea to choose an aspheric high-index design: it reduces aberrations and edge distortion, giving you better overall vision, and it makes the lens flatter and less bulging.
3. Your pupillary distance (PD)
The fourth and final factor is your pupillary distance. You should always choose a frame whose total width suits your PD. For example, if your PD is 65 mm, look for frames with a total width of around 130 to 140 mm, which is your PD multiplied by two plus a margin of up to 10 mm. Otherwise, larger lens blanks have to be used, and they will be thicker than lenses made from a standard 65 mm blank. If you are not sure about your frame size, here is how to measure your glasses frame.
Getting the best result
To get the best-looking result and the most comfortable glasses, you need to take all of these factors into account. If you still find it hard to choose your prescription glasses, don’t hesitate to ask an eye care specialist. A good optician will review your prescription and advise you on the most suitable frame and lenses, so you get the best possible look while keeping the cost under control.
Thin lenses for high prescriptions at Lens4Glasses
At Lens4Glasses we replace the lenses in your own glasses online, so you can keep the frame you love and still get thin, light lenses. Our single vision lenses can be upgraded to high-index 1.6, 1.67 or 1.74, and the price of each option is shown clearly on the product page before you order. Our single-vision lenses include a hard coating and anti-reflective treatment as standard. Choose your lens, enter your prescription and send us your frame: we will take care of the rest.