Why Do Some Contact Lens Powers Take Weeks to Arrive?

Two people look for the same lens from the same brand. One gets it straight away; the other is told to wait several weeks. The box size and packaging look identical. Only a few numbers differ, so why the gap?

Each power combination of a contact lens is a separate product, and the combinations multiply, so it is hard to keep every slot equally ready to ship straight away.

This article is about the general structure of the industry, not the circumstances of any one seller. We will work it out ourselves from the product ranges manufacturers have published. Slots here are a count of the specifications that can be made, not the quantity of stock actually sitting on shelves.

One power, one product

Let us start by counting lenses for short sight. In Johnson & Johnson's 2026 Canadian technical specifications sheet, one daily lens (ACUVUE OASYS 1-Day) has minus powers from −0.50 to −12.00. We use it as an example only because the published information is specific, not to recommend a particular product.

Steps are 0.25 up to −6.00 and 0.50 after that, making 35 slots in all. There are two base curves, 8.5 and 9.0, so multiplying gives 70 slots. Plus powers are not yet in this calculation.

The starting point is that slots cannot stand in for one another. However many −3.00 boxes there are, none will suit someone prescribed −3.25. Someone whose two eyes have different powers needs two slots at once. Differences between the eyes are covered in Why Do Your Right and Left Contact Lenses Have Different Powers?.

Add astigmatism and the multiplication begins

In the same sheet, the daily toric lens (ACUVUE OASYS 1-Day for ASTIGMATISM) is on a different scale, even though it has only one base curve, 8.5.

Each minus power slot takes a cylinder strength, and each strength takes an axis, the number for direction. From 0.00 to −6.00 alone there are 25 power slots, each with 64 combinations of cylinder and axis, giving 1,600 slots. Add the high minus and plus ranges and the total is 2,260.

Put the minus sides alone next to each other and you get 70 slots for the first lens and 1,780 for the toric lens, about 25 times as many. Only two more numbers need writing down, yet the result grows by multiplication, not addition.

Count box sizes and the slots grow again

This toric lens comes in boxes of 30 and 90, with plus powers in boxes of 30 only. If you separate box sizes too, that makes 2,260 types in boxes of 30 and 1,780 in boxes of 90, 4,040 in all.

Other manufacturers work on a similar or larger scale. A 2021 CooperVision announcement said one monthly toric lens comes in nearly 33,000 specifications. It is a product with spheres from +8.00 to −10.00 and axes in 10-degree steps.

Presbyopia correction multiplies in one more item. A 2023 article from the same company wrote that one lens correcting both astigmatism and presbyopia has more than 200,000 specifications. That is company material counting combinations of sphere, cylinder, axis and near power. We cannot assume every product is counted in the same way, so please read it as a number that gives a sense of scale.

How different are common and rare powers?

Having many slots does not mean demand is spread evenly across them. According to a 2011 paper analysing 11,624 glasses prescriptions, 35.7% of eyes had astigmatism of 0.75 dioptres or more. The figures fell quickly after that: 23.4% at 1.00 or more, 10.8% at 1.50 or more and 5.6% at 2.00 or more.

The same paper estimated that a range of sphere +6.00 to −9.00, three cylinder powers and 18 axes would need nearly 3,000 specifications and could cover 90% of people with astigmatism. Covering the rest means widening the range, and towards the edges fewer people are looking for each slot.

The manufacturer's sheet has the same shape. The toric lens above reduces its axes to 10, 20, 70, 80, 90, 100, 110, 160, 170 and 180 for high minus powers of −6.50 and beyond and for plus powers. Only directions close to horizontal and vertical remain. The sheet does not say why they were reduced.

Slots that ship straight away and slots made to order

The Cooper Companies' fiscal 2022 annual report says it produces lenses in high, medium and low volumes, giving custom lenses for high astigmatism as an example. The 2021 announcement mentioned above describes a wide-range toric lens as made to order. That does not mean cut by hand; it says this product is moulded too. How lenses are made is shown in Why Are Contact Lenses So Expensive?.

The time taken also depends on where the factory is. According to the 2023 article, after one made-to-order lens moved production for North American orders from the UK to New York in the United States, delivery time fell by more than half to an average of 7 days. Working backwards, that means the earlier average was more than two weeks. Orders from other regions, it says, continue to be made at the UK factory.

Those 7 days are one case, for one product in one region, and do not represent an industry average. “Several weeks” is better seen not as a fixed rule but as a result that varies with the product, ordering region and production site.

What to check while you wait

Being told to wait does not mean your eyes are unusual. It comes from a structure with very many slots. Even if a nearby power or a different axis is available straight away, it is not something to switch to on your own. The decision to change a power or axis belongs to the professional who prescribed the lens, and if you feel discomfort or your vision has changed, it is best to check with an ophthalmologist or optometrist.

Next time you look at a lens box, count the number fields on its side. If sphere, cylinder, axis and base curve are all there, that box is one slot among thousands.