Prescription Glasses Buying Guide

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Prescription Glasses Buying Guide

Prescription glasses use specific lenses to combat any defects of vision the user may have. Prescription glasses can assist with a number of defects including far or near sightedness.

Because of the personal aspect involved in the use of these glasses, it is extremely important that buyers choose a pair suitable for their eyes, as the use of incorrect lenses can cause further strain and potentially irreversible damage.

eBay is a great place to search for prescription glasses because the site offers a large selection at prices that may not be found in brick and mortar outlets or on other websites. This guide will examine the important aspects for consideration when purchasing glasses, and how to successfully use eBay to find an appropriate pair.

Understanding the Prescription

It is extremely important to be able to read the prescription, as this is the only way to ensure that the correct lenses are being selected. All eye prescriptions contain a number of headings with numerical values underneath. These headings refer to defects and the numbers relate to the strength of the defect or the lens required.

SPH (Sphere)

The sphere is the main part of the prescription and is measured in 0.25 increases. This indicates the required lens strength needed to correct defects and return focus to normal levels. A sphere with a minus sign indicates near sightedness while a sphere with a plus sign indicates farsightedness. 

CYL (Cylinder)

This specifies the strength of any astigmatism found in the eyes. Astigmatism creates blurred or distorted vision and is a result of an imperfectly curved lens. Not all prescriptions will have a cylinder and sometimes astigmatism is only present in one eye.

AXIS

The AXIS will only be present if there is a value in the cylinder box. The AXIS reveals where exactly in the eye the astigmatism is found. The measurement in the AXIS box will tell to what degree the Cylinder lens should be put.

ADD (Addition)

This is the additional correction required in the lens to allow for reading. The ADD is used to make reading, bifocal and varifocal glasses. The ADD signifies how much extra strength is needed in the glasses on top of the previous three categories. The ADD will be the same in both eyes, regardless of whether it is indicated on the prescription or not. ADD is only included when the glasses are being used for reading or close work.

PRISM

A Prism is used to correct special conditions and eye disorders such as squints or a lazy eye. Prisms do not assist with distance related defects, but instead are used to help keep both eyes working together.

The Pupillary Distance (PD) is the distance between the pupils. It is used to make sure that the lenses have correct centration in front of the eyes. The average PD of an adult is usually between 60 and 66 millimetres. To self-check Pupillary Distance, take the following steps:

  • Take a millimetre ruler and hold it up above the eyes in front of a mirror.
  • Close the right eye and place the ruler flat against the forehead.
  • Align the zero mark of the ruler to the centre of the pupil of the left eye.
  • Keeping the ruler steady, close the left eye and open the right.
  • Read the measurement that corresponds to the centre of the pupil of the right eye. This will give you the Pupillary Distance.
  • Repeat this process a few times to ensure that the measurement is correct.

Choosing Prescription Glasses

There are a number of factors to consider when searching for prescription glasses. Take some time to decide which frames and lenses will work best.

Choosing the Right Frame

Although not the most important aspect of choosing glasses, picking the right frame will guarantee that the glasses sit comfortably and balance the face’s shape.

Oval

Oval faces are usually evenly proportioned with high cheekbones and a curved jaw. The majority of frames suit this face shape, and modern geometric styles work particularly well with it.

Square

Deep foreheads and a wide, square jaw line define square face shapes. Oval and round frames work best with this face shape, as they soften the jaw. Angular and slim frames should be avoided, as these will emphasise sharp facial features.

Round

A round face shape consists of a wide forehead with full cheeks and a rounded jaw line. Round faces tend to be short in height. Angular, square and geometric frames are suitable for this face type as they draw attention to the eyes and top half of the face. Oval and rounded frames will make the face appear rounder than it actually is.

Rectangle

A broad, deep forehead, a square chin and a wide jaw define rectangular faces. Oval and round frames work well, as do wide frames with strong top lines. Slim, square and angular frames should be avoided.

It is important that the frame fits comfortably as to avoid irritation, so it is best to follow these steps:

  • The top of the frame should never be higher then the eyebrows.
  • The lower part of the frames should not sit on the cheeks, as this will cause irritation when smiling or laughing.
  • The frame should not be wider than the width of the face at the temples.
  • The inside of the frame’s arm should have three sets of numbers engraved in it. These are the lens diameter, the bridge width and the length of the arm.

The Lens

The lens is the most important part of a pair of glasses, as this is what corrects any eye defects. There are two types of lens available when buying prescription glasses.

Single Vision Lens

These have the same focal power from top of the lens to the bottom. They correct one field of vision and are most commonly used by people who have near sightedness, farsightedness or astigmatism.

Multifocal Lenses

(Bifocal and Trifocal)

These are used to correct more than one field of vision. Bifocal lenses are used to treat a condition called Presbyopia, and work by keeping the top of the lens for distant vision and the bottom for close vision. Trifocals work the same except they contain a centre focal point for intermediate vision.

There are other lenses that can be bought for use with specific activities such as prescription glasses for computer use, prescription sunglasses or prescription water goggles. There are also a number of coatings available to protect either the eye or the lens itself.

  • UV Protection provides defence against ultraviolet light that is found in sunlight. Ultraviolet light is capable of being extremely damaging to the eye, and can eventually lead to the development of cataracts in the pupil. A coating of UV Protection will prevent ultraviolet light from penetrating the lens, helping to keep eyesight safe and healthy.
  • Anti-Reflection coatings help deal with light bouncing off reflective surfaces and catching the lens. This is very helpful when driving or using a computer.
  • Some lenses are available with scratch resistant coating that keeps the lens free from small scratches. Scratches on a lens can cause disruption and distraction when being worn.

Buying with Confidence

The Seller’s Information box is a quick way to see a seller’s history and how other buyers have rated them. It is advised that buyers only deal with sellers that have received a high percentage of positive feedback. If a seller has a large number of negative comments then return to the listings page and search for a different prescription glasses listing.

Conclusion

eBay hosts to a large number of prescription glasses for sale, often at better value then that found in eye ware stores or other online sites.

It is best to ensure that the frames will fit the face shape and will not be uncomfortable. Remember to examine the actual prescription to understand what exactly your eye deficiency is and what lenses are needed.

Always buy prescription glasses from sellers who have received a high level of positive feedback, because this will guarantee that the glasses will be as described and will arrive on time.

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