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The following can be used as a guide to enable you to select the right frame. Face Shape Rectangular; If you have a long face and angular jaw line you may need a rounded frame to de-emphasize the squareness. A deep frame with temples set in the middle. Frame shape should take an aprropriate proportion of the face Heart; Also known as an inverted triangle. Characterized by a wide forehead, high cheek bones and pointy chin.Top of the head is larger and more prominent than the bottom. For balance you select the opposite. A frame that becomes wider at the bottom to provide more width to the lower half of the face and low set temples Inverted heart; Inverted heart shape is also unbalanced. Forehead and top of the head is narrow, widening out to a wide and prominent jaw. Use a frame with high set temples and wide at the top and narrow at the bottom Round; This shape is the exact opposite to the square face and requires the exact opposite remedy with regards to frame shape. Use an angular frame shape to de-emphasize the roundness. Remedy used for lengthening the square face is also required for round face. Use a shallow frame with high set temples Oval; Considered to be the ideal face shape. Almost any frame shape will suit you! There are no dominant bone structures and nothing needs to be de-emphasised. Please note, outrageous shapes may detract from the 'ideal' nature of the face.
A bifocal consists of two zones of vision that include the distance on the top part of the segment, and near in the lower part. There is a visible line within this lens. You may prefer this lens type if you have been used to wearing this. The main difference between varying bifocal lens types is the size and shape of the segment. Most common types are 'round seg, D seg and E-line A varifocal is a blended lens which has three zones of vision being distance, intermediate and near. There is no visible line and simply looks like a single vision lens. No one is able to tell of your age and that you need reading spectacles. Great for office workers and general day use. This lens type allows the wearer to see at every working distance
An optical defect whereby vision is blurred due to inability of the eye to focus on an object into a sharp focused image on the retina. This is due to irregularity of the corneal surface for example this may be shaped like a 'rugby ball'. Also know as the cornea having a toric curvature, hence the need for toric contact lenses for those who have astigmatism.
Sphere refers to the amount of nearsightedness (myopia) or farsightedness (hyperopia). If the sphere number is negative, the patient is nearsighted. If it is positive, he or she is farsighted. Sphere numbers of zero are called "plano" Cylinder refers to the amount of astigmatism. If no astigmatism is present, then the prescription will only have a number for sphere. Cylinder can be expressed as either a positive or negative number. Most opticians use positive numbers, known as "plus cylinder format", while most others use negative numbers, know as “minus cylinder format”. Prescriptions in minus cylinder need to be converted into plus cylinder in order to accurately read the following tables. To convert a prescription, simply add the sphere and cylinder to obtain the converted sphere and change the cylinder to a positive number. If the axis is =>90, then subtract 90 for the new axis, otherwise add 90. Prescription Conversion Example original prescription in minus cylinder = -3.25 -1.75 x 176 -3.25 + (-1.75) = -5.00 = new sphere +1.75 = new cylinder 176 - 90 = 86 = new axis -5.00 +1.75 x 86 = converted prescription in plus cylinder Axis refers to the direction on the clock hour of the astigmatism. It is not necessary to understand anything about the axis number when contemplating laser vision correction, nor is it necessary to understand any of the following terms that are occasionally found on a prescription: "Add", "Prism", "Base Curve", "Diameter" and "Pupillary Distance (PD)". However, if a prescription contains the word “Prism”, this finding should be mentioned to the doctor, as it may indicate an eye alignment problem that makes laser vision correction inadvisable.