If you or anyone you have known ever tested his eyes, you will be given an eyeglasses prescription if you needed it.
An eyeglasses prescription is often confusing for people, the code words used by an optometrist, or an ophthalmologist often surprise you but don't worry we are here to help decode the prescription.
Abbreviations used in a Prescription
SPH - means sphere, it is the power of the lens that corrects the eye.
CYL–means cylinders, and it shows the amount of astigmatism present in the eye
Axis–it is the axis at which your cylindrical power is present.
V.A.–it means visual acuity; it is the visual acuity examiner has achieved with your eye power.
A normal prescription first of all contains the general data of the patient such as his/her name, age, sex, and the date of examination. A prescription card contains both the correction of distance vision and near vision.
What does a different number mean?
Commonly spherical, cylindrical powers are quantified numbers that often come with a '+' plus sign or a '-' negative sign.
A plus sign '+' represents a person with far-sightedness. A plus or a converging lens is a convex type of lens that converges the light rays coming from infinity.
A minus sign '-' represents a person with near-sightedness. A minus or a diverging lens is a concave type of lens that diverge the light rays coming from infinity.
If in prescription +1.00D is written, the person has 1.00 dioptre of glass strength needed to correct farsightedness.
Similarly, if prescription -1.50D is written, the person has 1.50 dioptre of glass strength needed to correct near-sightedness.
What are distance and near prescription?
A patient's prescription has two columns, one for distance vision and one for near vision.
The distance column prescription contains the corrective visual aid needed for distance while the near column prescription contains the visual aid needed for near vision.
Distance correction is generally because of refractive errors such as Myopia, Hypermetropia, and Astigmatism.
Near correction is required for treating the effect of Presbyopia.
Presbyopia is a physiological process in which long-sightedness is caused by the loss of elasticity of the lens of the eye, occurring typically in middle and old age.
Lens Recommendation
An eyeglass prescription might also contain a note from an optometrist or ophthalmologist recommending the type of lens the patient should consider. Your Lens can be: -
Progressive or Bifocal–it is the type of lens in which a distance and a near vision correction are both present. Sometimes intermediate power is also present.
Anti-reflection Coating–it is the coating present on the lens to reduce the glare problem for the patient. It makes it easier for the person to see at night or work on the computer.
Photochromatic lenses–these lenses get darker when exposed to sunlight.
High-Index Lenses – they have a higher refractive index. They make higher-power lenses lighter and thinner.
Will my Contact Lens prescription will be different from spectacles?
YES, the contact lens prescription will be different from the spectacle prescription as the contact lens directly sits on your cornea which changes its back vertex distance.
A contact lens prescription contains some additional info, such as –
Base curve - curvature of your cornea
Diameter–total diametrical length of your contact lens.
Lens type, expiration date, and brand identity are also mentioned sometimes.
At last, the prescription signature of an optometrist or an ophthalmologist is done which signifies the identity of the examiner.