You’ve got your prescription sorted. ✓

You’ve even measured your pupillary distance. ✓

But because of the way varifocals work, we need to ensure your pupils are correctly positioned behind your new lenses. So, what is OC measurement when it’s at home?

 

Ocular centre height refers to vertical positioning of your pupils behind each of their respective lenses. This is measured in mm from the centre of each pupil to the lowermost section of the lens within the rim of a glasses frame.

 

In other words, we use your pupillary distance and your OC height to horizontally and vertically align your pupils with the middle of each of your lenses.

Oh, and because your new glasses are a different shape, this measurement is entirely unique to how your specific glasses frame rests on your head.

Your OC changes from frame to frame.

 

HOW DO YOU MEASURE OC HEIGHT FOR GLASSES?

 

Man measuring his ocular height with a white ruler

Using a plastic ruler, this OC measurement would be approximately 29mm from the centre of his pupil to the bottom of his lens.

 

With help

  • Stand/sit in front of your assistant

  • Wear the glasses you’re ordering lenses for

  • Your assistant vertically holds a plastic ruler against one lens

  • They align the 0mm mark with your pupil centre

  • They assess the distance to the bottom of your lens

  • Note heights according to your left & right, not theirs.

 

On your own

  • Stand/sit in front of a mirror

  • Wear the glasses you’re ordering lenses for

  • Vertically hold a plastic ruler against one lens

  • Align the 0mm mark with your pupil centre

  • Assess the distance to the bottom of your lens

  • Note heights according to your left & right

 

OC height tips

  • Only measure the lens, not the frame

  • Use a plastic ruler to prevent scratches

  • If it helps, close one of your eyes to help your focus

  • Brace the ruler against your nose & the frame/lens

  • Left & right are from your perspective, not your assistants

 

Measuring your vertical optical centre for sunglasses?

With help from a friend, ask them to shine a torch/light on the lens to illuminate your eye behind. This way they can accurately measure your OC height from the front of each lens.

 

Illustration of ocular height measurements overlaying a man wering glasses

 

WHY IS OC HEIGHT IMPORTANT FOR VARIFOCALS?

Every lens has an apex. This is the optical centre of a lens which should always be aligned with the centre of each of your pupils.

Optically speaking, this is called centration which is achieved by locating your pupils directly behind the middle of each lens whilst wearing a specific glasses frame. This is achieved using horizontal and vertical alignment in addition to the distance between your lenses (DBL).

  • Horizontal centration is measured using your dual pupillary distances

  • Vertical centration is measured using your ocular heights

In the context of varifocals, the importance of pupillary height is so that the neutral gaze of your eyes aligns with the centre of the lens in order to maximise progressive power.

Accurate centration means your pupil is in the optimal position to select the correct area of your lens to look through to see properly.

For varifocals, proper vertical centration prevents you from having to tilt your head to see through the correct portion of your lenses. In the workplace, this can lead to postural issues such as neck or back pain.

HOW DO YOU MEASURE PD FOR PROGRESSIVE LENSES?

For accuracy, progressive lenses require what’s called a dual pupillary distance.

This is a facial measurement from the centre your pupil to the centre of your nose for each of your eyes. The easiest method to do this is with a pupilometer with a slot for your nose which mimics the bridge of a glasses frame.


 

Free PD ruler made from PDF download on blue background


Key notes

  • OC height is always measured in mm

  • Always measure your OC from the bottom of the lens

  • Your OC's & dual PD are susceptible to change if your glasses move on your face. Therefore, they aren't static and have a degree of movement tolerance.

  • Your PD never changes, but your OC height does.

  • For sunglasses, use a torch to see your pupils

 

Ordering varifocals online can be simplified if you have the proper centration measurements. If you invest the time to measure your vertical optical centre, you’ll save time and money on your progressive lens investment.


Raw Red Peppers


Bell peppers give you the most vitamin C per calorie. That's good for the blood vessels in your eyes, and science suggests it could lower your risk of getting cataracts. It's found in many vegetables and fruits, including bok choy, cauliflower, papayas, and strawberries. Heat will break down vitamin C, so go raw when you can. Brightly colored peppers also pack eye-friendly vitamins A and E.

Sunflower Seeds and Nuts


An ounce of these seeds or almonds has half the amount of vitamin E the USDA recommends for adults each day. A large study found that vitamin E, together with other nutrients, can help slow age-related macular degeneration (AMD) from getting worse. It may also help prevent cataracts. Hazelnuts, peanuts (technically legumes), and peanut butter are also good sources of vitamin E.

Dark, Leafy Greens


Kale, spinach, and collard greens, for example, are rich in both vitamins C and E. They also have the carotenoids lutein and zeaxanthin. These plant-based forms of vitamin A lower your risk of long-term eye diseases, including AMD and cataracts. Most people who eat Western diets don't get enough of them.

Salmon


Your retinas need two types of omega-3 fatty acids to work right: DHA and EPA. You can find both in fatty fish, such as salmon, tuna, and trout, as well as other seafood. Omega-3s also seem to protect your eyes from AMD and glaucoma. Low levels of these fatty acids have been linked to dry eyes.

Sweet Potatoes


Orange-colored fruits and vegetables -- like sweet potatoes, carrots, cantaloupe, mangos, and apricots -- are high in beta-carotene, a form of vitamin A that helps with night vision, your eyes' ability to adjust to darkness. One sweet potato also has more than half the vitamin C you need in a day and a little vitamin E.

Lean Meat and Poultry


Zinc brings vitamin A from your liver to your retina, where it's used to make the protective pigment melanin. Oysters have more zinc per serving than any other food, but you don't have to be a shellfish lover to get enough: Beef, pork, and chicken (both dark and breast meat) are all good sources.

Beans and Legumes


Prefer a vegetarian, low-fat, high-fiber option to help keep your vision sharp at night and slow AMD? Chickpeas are also high in zinc, as are black-eyed peas, kidney beans, and lentils. A can of baked beans will do the job, too.

Eggs


It's a great package deal: The zinc in an egg will help your body use the lutein and zeaxanthin from its yolk. The yellow-orange color of these compounds blocks harmful blue light from damaging your retina. They help boost the amount of protective pigment in the macula, the part of your eye that controls central vision.

Squash


Your body can't make lutein and zeaxanthin, but you can get them from squash all year long. Summer squash also has vitamin C and zinc. The winter kind will give you vitamins A and C as well as omega-3 fatty acids, too.

Broccoli and Brussels Sprouts


These related veggies come with another winning combination of nutrients: vitamin A (as lutein, zeaxanthin, and beta-carotene), vitamin C, and vitamin E. They're all antioxidants that protect the cells in your eyes from free radicals, a type of unstable molecule that breaks down healthy tissue. Your retinas are especially vulnerable.



You've passed your 40th birthday, and you're having trouble reading or seeing objects up close. Maybe you've tried to carry store-bought readers around with you, but your eye doctor suggests progressive lenses. Should you take the plunge?

What Are Progressive Lenses?

Progressive lenses have three prescriptions in one pair of glasses. That allows you to do close-up work (like reading a book), middle-distance work (like checking out a website on a computer), or distance viewing (like driving) without needing to change your glasses. They're sometimes called multifocal lenses.

Progressive lenses are an update on bifocal and trifocal lenses. Both of these more traditional types of glasses have telltale lines in the lenses. Progressives have a seamless look. Sometimes they're called "no-line bifocals," but that's not quite right. It would be more accurate to call progressive lenses "no-line trifocals."

Who Uses Progressive Lenses?

Almost anyone with a vision problem can wear these lenses, but they're typically needed by people over age 40 who have presbyopia (farsightedness) -- their vision blurs when they're doing closeup work like reading or sewing. Progressive lenses can be used for children, too, to prevent increasing myopia (nearsightedness). 

Talk to your doctor to see if progressives are an option for you.

 

Benefits of Progressive Lenses

With progressive lenses, you won't need to have more than one pair of glasses with you. You don't need to swap between your reading and regular glasses.

Vision with progressives can seem natural. If you switch from viewing something up close to something far away, you won't get a "jump" like you would with bifocals or trifocals. So if you're driving, you can look at your dashboard, at the road, or at a sign in the distance with a smooth transition.

They look like regular glasses. In one study, people who wore traditional bifocals were given progressive lenses to try. The study's author said most made the switch for good.

Drawbacks of Progressive Lenses

It takes time to adjust to progressives. You need to train yourself to look out of the lower part of the lens when you're reading, to look straight ahead for distance, and to look somewhere between the two spots for middle distance or computer work. Some people never adjust, but most do. During the learning period, you may feel dizzy and nauseas from looking through the wrong section of lens. There may also be some distortion of your peripheral vision (what you see on the edges when looking straight ahead).

Another thing to consider is the cost. Progressive lenses cost at least $100 more than traditional bifocals.

Tips for Adjusting to Progressive Lenses

If you decide to try them, use these tips:

  • Choose a quality optical shop that can guide you through the process, help you pick a good frame, and make sure the lenses are perfectly centered over your eyes. Poorly fitted progressives are a common reason why people can't adapt to them.

  • Give yourself one or two weeks to adjust to them. Some people may need as long as a month.

  • Make sure you understand your eye doctor's instructions on how to use them.

  • Wear your new lenses as often as possible and stop wearing your other glasses. It will make the adjustment quicker.