Asked by: Jerod Weissnat
Character: 5/5(54 votes)
base curve The base curve isradius of the sphere on the rear part of the lensdescribes the prescription (the lower the number, the steeper the curve on the cornea and lens, the higher the number, the flatter the curve on the cornea and lens). https://pl.wikipedia.org› wiki › Radius_of_basic_curves
Is there a big difference between the base curve of 8.4 and 8.6?
Research shows that a single base curve of 8.4mm results in a "good or better" fit in approximately 90% of people,1and the base curves of 8.4 mm and 8.6 mm togethercovered 98%people.
What is the normal BC value for contact lenses?
Typical range of baseline valuesfrom 8.0 to 10.0 mm, although it can be flatter (than 7.0mm) if you have a rigid gas permeable lens. A person with a higher base curve number has a flatter cornea (clear, front surface of the eye) compared to a person with a lower base curve number, indicating a steeper cornea.
Is BC on contacts important?
Never order contact lenses with a base curvediffers from the recipe. This can cause eye damage and vision problems. This is especially true for people who buy colored cosmetic contact lenses, which often come in a standard size.
What do BC and DIA mean for contacts?
base curve(BC): A number that describes the shape of the contact lenses. Depending on the slope or flatness of your cornea, your prescription dictates how big your contact lens should be. 2. Diameter (DIA): A number that indicates the length of the lenses to ensure that they cover the cornea correctly.
39 related questions were found
Is the 0.75 eye prescription bad?
For both types, the closer you are to zero, the better your vision. For example, while readings of -0.75 and -1.25 qualify as mild myopia, a person with a spherical error of -0.75 is technicallycloser to 20/20 vision without glasses.
What happens if you wear contacts with an incorrect base curve?
If your lenses are the wrong diameter or base curvature, you will likely feel like there is always something in your eye. If the lenses are too flat, the eyelids will push them out when you blink. Incorrect lens sizeit can even cause wear and tear on the cornea.
How important is the BC number for contacts?
It stands for "BC" or base curve measurementposterior curvature of the contact lensin millimeters. This is important for comfort because the BC of contact lenses should follow the natural curvature of the eye as closely as possible to ensure a better fit when wearing the contact lenses.
What does BC mean in contact lenses?
base curve(BC): the base curve determines the type of adjustment required for the lens to fit the curvature of the eye; this is usually written in millimeters or sometimes the words flat, medium or steep.
How do you know your BC for contacts?
Base curve (BC): This figure shows howarched your contactit's a lens. Your optician will try to match the curvature of your contact lens to the curvature of your eye to find the contact lens that fits you best. For example, 8.4 BC
What is the average BC of contacts?
The base curve, or BC, is the radius of the back of the contact lens, the part that sits on the eye 3. According to Laser Eye Surgery Review, the average base curve measurement isbetween 8.0 and 10.0 3.
How can I find my BC for contacts?
A simple rule of thumb to estimate the base curve of the lens on a MINUS POWER lens
- For negative power lenses, take half the spherical equivalent plus 4 diopters. For example -4.00 orb power, you would use -2.00 (half SE) + 4D, which would give you 2BC.
- tj. Rx -4,00sph -> [(-4,00 x 0,50)+ 4,00D] = 2,00 pne.
What happens if you wear glasses of the wrong size?
If your contact lens fits too tightly around the eye, it can deprive the cornea of the oxygen and nutrients it needs, leading to discomfort and tight lens syndrome. Continuing to wear contact lenses that are too tight can lead to serious eye problems such as:Corneal ulcer.Loss of sight.
Is there a big difference between the base curve of 8.4 and 8.8?
The base curve of 8.4 mm probably still fits most eyes best. In cases where the 8.4mm lens is too steep, the 8.8mm lens canallows for a flatter option. This is more necessary in smaller eyes and probably in some very flat corneas.
What is the difference between 14.2 and 14.5 diameter needles?
There really isn't that much difference between the two. Some manufacturers only make 14.2mm needles, while others make themDiameter 14,0 mmAnnouncement. ... Many 14.0mm lens wearers use 14.5mm or 14.8mm lenses to show the doll effect on the eyes.
How to calculate the base curve for contact lenses?
base curve= 0,95 * 34,82 D = 33,07D and then round up or down to the nearest full diopter to obtain the following final base curve for use with excessive contact lens refraction: Base curve = 33.00 D (actual measured base curve is 32.95 D)
How do I know if my contacts are left- or right-handed?
Hold the lens near the centerbetween the tips of the index finger and thumb. Gently squeeze the lens as if you were trying to fold it in half. Clamps, look at the edge of the lens. If it faces up, or if the edges appear to touch, the lens is on the right.
How bad is my vision if I wear contact lenses?
In the United States, a person is legally blind if: Vision with glasses or contact lenses is 20/200 or better, or. Their field of vision is20 degrees or lessin the better eye.
What is the largest prescription for daily contact lenses?
Daysoft creates the most powerful daily contact lenses on the market. Daysoft has created the most powerful daily dioptric contact lenses on the market-25.00D.
What does it mean to add power to contact lenses?
The summation is normally written in diopters and written as a plus degree (+). Thisindicates the magnification power in multifocal mode(other names include bifocal or varifocal contact lenses).
What does D stand for contacts?
Sphere (SPH): The power of the lens measured in diopters (D), whichcorrects nearsightedness or farsightedness. If the number under this heading contains a minus sign (–), you are nearsighted; if it has a plus sign (+), it means you are farsighted.
Does 0.00 mean power plug?
of
For prescription glasses 0.00 (zero focusing power required) means good eyesight. In general, the further away from zero (regardless of whether the number is positive or negative), the worse your vision is and the greater the need for vision correction.
How to recognize that your contacts are not the right size?
If your eye is flat and you wear a bowl contact lens, the lens will befits too tight. You will feel the edge of the lens where it rests on your eye, the eye may become red as the day progresses, and inflammation may develop.
How do I know my eye size for contact lenses?
in general,Your eye doctor will use a keratometer to measure the curvature of your corneawhich is the front of the eyes - where the contacts rest. These numbers help determine the lens diameter and base curve that will appear on your contact lens prescription.
How is the sensitivity of contact lenses corrected?
Five Ways to Fight Contact Lens Intolerance (CLI)
- Laser vision correction. LASIK is the most radical treatment for CLI. ...
- Glasses. For some people, glasses are both a fashion and a visual tool. ...
- Artificial tears. ...
- Diet and nutritional supplements. ...
- Carry and care.
FAQs
What does bc mean in contacts? ›
BC: BC stands for base curve, which is the curvature of your contact lens (you wouldn't find this abbreviation on a
The 8.4mm base curve is still the likely best fit for the majority of eyes. In instances when the 8.4mm lens is too steep, the 8.8mm lens allows a flatter option. This is more likely needed in smaller eyes, and possibly in some very flat corneas.
What does 8.4 and 8.6 mean on contacts? ›Contact lenses are prescribed according to the curvature of your cornea, and in the curve sequence you are describing, there would typically be a steep curve (8.4), a medium curve (8.6), and a flat curve (8.8).
What does BC 8.6 mean? ›BC: Base Curve (usually a number between 8 and 10) If your brand only comes in one base curve, your prescription will not contain a BC value. Like clothing, just because you're a BC 8.6 in one brand doesn't mean you'll be the same in another brand.
Is there a big difference between 8.5 and 8.6 base curve? ›A lens with an 8.5 curvature is identical in curvature to an 8.6 , it's just a marketing ploy to make it look different. The difference between an 8.5 and an 8.6 isn't the curvature , but the fact that it is a different lens.
What happens if you wear the wrong base curve? ›You should never order contact lenses with a base curve that is different from your prescription. This can damage your eyes and cause problems with vision. This is especially important for people who purchase cosmetic coloured contact lenses, which are often of a standardised size.
What happens if the base curve is too big? ›A base curve that is too big will cause the contact lens to not sit properly on the cornea. While less medically dangerous than wearing an overly-small base curve, it can still cause annoyance from the contact lens shifting around or poor vision.
What is the best base curve for contacts? ›The most basic rule is that you always want the base curve to be as close to +6.00 as you can get and still have the Rx work. In theory +6.00 should always give you the best possible combination of curves for weight, optics, etc.
What is the normal BC for contact lenses? ›BC: BC stands for base curve, which is the curvature of your contact lens (you wouldn't find this abbreviation on a glasses prescription). It's measured in millimeters (mm) and should align well with the curvature of your eye. It's always a number between 8 and 9.
What base curve do I need? ›Typical base curve values range between 8.0 and 10.0 mm, though it can be flatter (from 7.0mm) if you have a rigid gas-permeable lens. A person with a higher base curve number has a flatter cornea (the clear, front surface of the eye) compared to someone with a lower base curve number, which indicates a steeper cornea.
Is there a big difference between 8.4 and 8.6 base curve? ›
The difference between an 8.4 and 8.6 base curve may seem small, but it can significantly impact the fit and comfort of your contact lenses. An 8.4 base curve is slightly steeper than an 8.6, which means it will fit more closely to the eye's curvature.
What happens if you wear the wrong size contacts? ›What Happens if You Wear the Wrong Size Contact Lenses? Dislodged Contact. If the diameter (width of the contact lens) is too wide or the base curve is too flat, the contact lens will fit loose on your eye and can slip out of place or dislodge when you blink or rub your eyes.
What is the most common contact lens size? ›How to Know the Right Contact Diameter Size. The average contact lens diameter size is around 14mm, given that the average cornea is about 12mm in diameter. If you have smaller eyes, you may be closer to the 14mm diameter size, whereas big eyes may land more towards the 14.5mm end of the range.
Can I wear a 8.6 in base curve? ›8.6 BC is a pretty average Base Curve for soft lenses. That means that 50% of wearers will do OK with that BC, but 25% will need a steeper curve, and 25% will need a flatter curve. Since we are discussing soft lenses, they drape over the cornea, and there is some wiggle room for base curves.
What base curve is astigmatism? ›You can get base curves ranging from 7 to 9.5 mm and diameters as small as 12.5 mm. The lenses can be made with up to 15.00 D of cylinder and customizable to a 1 degree axis orientation.
Does base curve have to be exact? ›For hard contact lenses, this measurement is essential. The base curve number would be a number between 8.0 and 10.0 millimeters and would be more precise because these lenses need to fit just right. Now that most contact lenses dispensed are soft lenses, this measurement doesn't need to be quite as precise.
Does the BC in contacts matter? ›The base curve is an important part of your contact lens prescription, and your prescription will be deemed “invalid” without it. The back curve has to be determined to appropriately fit the front curve of the cornea (the clear dome over the color part of the eye) so that the contact lens fits comfortably.
Why doesn't my prescription have a base curve? ›If your prescription does not contain a Base Curve value, this is likely because your brand of lens only comes in one base curve. Base Curve values are a bit like clothes sizes - just because you are a Base Curve 8.6 in one brand doesn't mean you will be the same in another brand.
Does base curve matter for astigmatism? ›Yes they do matter. The BC, or base curve, is measured based on your cornea's curvature. If the base curve is too small, it'll squeeze your eye, and if it is too big, it won't stay on your cornea.
How important is the base curve and diameter on contact lenses? ›The base curve refers to the curvature of the back surface of the lens, while the diameter is the width of the lens. These measurements are crucial for ensuring the contact lenses' comfortable and safe fit on the wearer's eyes.
How does BC affect contact lenses? ›
The 'BC' or base curve measurement indicates the back curvature of your contact lens, in millimetres. This is important for comfort, as the BC of your contact lenses should match your eye's natural curve as closely as possible to ensure a better fit when you are wearing your contact lenses.
What is the best base curve for a flat cornea? ›Larger corneas may need the flatter 8.8 mm base curve, while smaller corneas may achieve a better fitting relationship with the steeper 8.5 mm base curve.
How do I figure out my contact lens base curve? ›Generally, your eye doctor will use a keratometer to measure the curve of your cornea, which is the front surface of the eyes – where contacts rest. These numbers help to determine the lens diameter and base curve that appear on your contact lenses prescription.
Can base curve affect vision? ›The base curve of a lens may affect certain aspects of vision, such as distortion and magnification, and wearers may notice perceptual differences between lenses with different base curves.
How do you flatten the base curve on a contact lens? ›Flattening the base curve by increasing the base curve value or decreasing the overall diameter of the contact lens will decrease the sagittal depth and correct for a tight fitting lens.
What does a 8.7 BC mean on contacts? ›Base Curves
For soft lenses, those numbers are in millimeters of radius (8.4mm or 8.7mm) and they can be divided into tenths. With millimeters of radius, the smaller the number, the more curved or steeper the lens will be. So, an 8.4mm lens will be more curved or steeper than an 8.7mm lens.
Rigid Gas-Permeable Contact Lenses
RGP lenses consistently hold their shape on the eyes and create a pool of tears over the cornea that helps correct the effects of astigmatism.
Basecurve (BC): This number indicates how curved your contact lens is. Your optician will try and match the curve of your contact lens to the curve of your eye to find the best fitted contact lens for you. E.g. BC 8.4.
Does your base curve change over time? ›Base curve can also change as you wear a contact lens based on environmental factors like the lens drying out, temperature changes, and exposure to makeup or soaps.
What is the average size of a contact lens? ›Most contact lenses come in a standard 14.2 mm diameter, but this is not the right size for everyone – especially patients with small corneas and tight lids. For them, a smaller 13.6 mm lens will result in a better fit and improved comfort.
Is it OK to switch contact lens brands? ›
The only time that changing contact lens brands will be required is when the prescription changes to a value that is not made by the current brand. If astigmatism develops, nearsightedness increases or there are abnormalities in the eye, special contact lenses that can meet these needs can be used.
Do all contacts have the same base curve? ›There are different Base Curve values for different contact lens. The measurement affects how the contact lens fits on your eye. Different Base Curve values can change how you feel and see from the lens.
Why do my contacts feel like they don't fit? ›Your lenses are not properly fitted
If you always feel as if you have something in your eye, improper lens fit could be the problem. Fitting issues are a common culprit, especially in instances when the patient is only having problems with discomfort in one eye.
Risks of wearing contacts too long
Corneal ulcers (infectious keratitis): An open sore in the outer layer of the cornea. Hypoxia: A lack of oxygen that can lead to abnormal blood vessel growth into the cornea. Damage to corneal stem cells needed to keep the cornea clear for good vision.
Wearing the incorrect vision prescription will not cause vision to worsen, but a person may experience eye strain and headaches as an effect of the wrong prescription.
How do I know my contact size? ›In a simple approach, a card or ruler showing different pupil sizes is held next to your eye to determine the best match. Your eye doctor may hold a pupil gauge next to your eye to determine the approximate size of your eye's pupil as part of your contact lens eye examination.
What are the 3 types of contacts? ›- Soft Contact Lenses. Soft contact lenses are made of soft, flexible plastics that allow oxygen to pass through to the cornea. ...
- Rigid Gas Permeable (RGP) Contact Lenses. ...
- Extended Wear Contact Lenses. ...
- Disposable (Replacement Schedule) Contact Lenses.
Although, not everyone can wear them comfortably. Eye conditions, such as dry eye disease or blepharitis, may make wearing contacts uncomfortable and risky. A severe refractive error, allergies, or contact lens intolerance can also make wearing contact lenses difficult.
Is 8.6 and 8.7 BC a big difference? ›“Is there a big difference between 8.6 and 8.7 base curve in contact lenses?” No, the difference is small. The 8.7 curve is . 1mm flatter, but since these are soft lens curvatures, and soft lenses assume some of the shape of the cornea, the fitting value won't be changed dramatically.
What number is strong astigmatism? ›Mild Astigmatism <1.00 diopters. Moderate Astigmatism 1.00 to 2.00 diopters. High Astigmatism 2.00 to 4.00 diopters. Extreme Astigmatism > 4.00 diopters.
What lens shape for astigmatism? ›
Whether you end up with a prescription for glasses or contacts, your astigmatism can be corrected with cylindrical lenses (as opposed to spherical lenses). Cylindrical lenses will properly correct astigmatism by refracting light onto a single point on the retina.
What is a good astigmatism? ›Astigmatism is measured in diopters. A perfect eye with no astigmatism has 0 diopters. Most people have between 0.5 to 0.75 diopters of astigmatism. People with a measurement of 1.5 or more typically need contacts or eyeglasses to have clear vision.
What is 8 base lens curvature? ›An 8-base curve is considered high and creates a wraparound frame shape. An 8-base curve provides the most protection from the sun and allows the frames to hug your head, which is why most sport glasses utilize an 8-base, or even a 9-base frame.
Is there a big difference between 8.4 and 8.7 base curve? ›Base Curves
For soft lenses, those numbers are in millimeters of radius (8.4mm or 8.7mm) and they can be divided into tenths. With millimeters of radius, the smaller the number, the more curved or steeper the lens will be. So, an 8.4mm lens will be more curved or steeper than an 8.7mm lens.
The most basic rule is that you always want the base curve to be as close to +6.00 as you can get and still have the Rx work. In theory +6.00 should always give you the best possible combination of curves for weight, optics, etc.
Should I get 8.4 or 8.6 base curve? ›The difference between an 8.4 and 8.6 base curve may seem small, but it can significantly impact the fit and comfort of your contact lenses. An 8.4 base curve is slightly steeper than an 8.6, which means it will fit more closely to the eye's curvature.
What is the ideal base curve of contact lens? ›Typical base curve values range between 8.0 and 10.0 mm, though it can be flatter (from 7.0mm) if you have a rigid gas-permeable lens. A person with a higher base curve number has a flatter cornea (the clear, front surface of the eye) compared to someone with a lower base curve number, which indicates a steeper cornea.
What is the most common base curve for contacts? ›Studies show that a single base curve of 8.4mm managed a “good or better” fit in approximately 90% of individuals,1 and base curves of 8.4mm and 8.6mm together encompassed 98% of individuals.
Does BC on contacts have to be exact? ›BC and DIA
Base curve and diameter measurements refer to the shape and size of your eye. The base curve determines the curvature of your contact lens. The diameter measures how wide your lens will be. To ensure that your lenses fit against your cornea comfortably, these measurements must be precise.
The base curve is an important part of your contact lens prescription, and your prescription will be deemed “invalid” without it. The back curve has to be determined to appropriately fit the front curve of the cornea (the clear dome over the color part of the eye) so that the contact lens fits comfortably.
What is the best base curve for steep cornea? ›
Larger corneas may need the flatter 8.8 mm base curve, while smaller corneas may achieve a better fitting relationship with the steeper 8.5 mm base curve. Due to subtle differences in individual eyes, a two-base curve system is helpful in achieving the best fitting relationship possible.
Is there a big difference between 8.3 and 8.6 base curve? ›Conclusions: The slightly better lens fitting characteristics and comfort of the lens with the 8.3 base curve versus the 8.6 base curve are attributed to the lower movement of the lens with the 8.3 base curve.
Is there much difference between 8.6 and 8.7 base curve? ›“Is there a big difference between 8.6 and 8.7 base curve in contact lenses?” No, the difference is small. The 8.7 curve is . 1mm flatter, but since these are soft lens curvatures, and soft lenses assume some of the shape of the cornea, the fitting value won't be changed dramatically.