Monofocal glasses are those that correct nearsightedness, farsightedness or astigmatism. The entire lens has the same graduation. In cases of people normally older than 40 years old, they need one prescription for distance and a completely different one for near because they start with eyestrain, in this case, they need a progressive lens that has all the prescriptions they need for all distances from far to near.
In cases of people who have never worn glasses and suddenly at the age of about 40 years start to see poorly up close, you can solve their problem with a near glasses to see well up close but with those glasses are not useful to see far away because far away the graduation is completely different, or no graduation is necessary. Then they should remove the glasses for distance vision. In case you do not want to be continuously removing and putting on glasses, the only solution is to use progressive glasses.
Depending on the type of refractive error the person has and the value of the refractive error, there are several types of monofocal lenses. They are differentiated by their refractive index, which determines the thickness of the lens:
Monofocal 1.5
Monofocal 1.6
Monofocal 1.67
Monofocal 1.74
Monofocal 1.8
Monofocal 1.9
In this way, if there is a low myopia value, the lens will not be very thick, so a 1.5 monofocal will be enough. On the other hand, if there is high myopia where the lens is already thick due to the prescription, then we will have to choose a thinner fabrication so that the glass is not heavy and thin, then we will choose a 1.9 monofocal.
Generally, choosing a 1.8 or 1.9 monofocal is a special case for very high prescriptions. A range between 1.6 and 1.74 are common monofocal lenses, even if you have a medium prescription, since a 1.6 monofocal will always look better, thinner and lighter than for example a 1.5.
TREATMENT
Monofocal lenses, apart from choosing the reduction of the lens, it is also possible to choose the type of treatment that the lens can have. It will depend on the protection we need or the rhythm of life we lead, it is not the same for a person who spends most of the day in front of screens than for a person who spends most of the day outdoors looking at distant distances.
- Screen protection treatment: this is an extra protection that is applied to all the lens and what it filters part of the blue light coming from the screens, tablets or mobile phones. By filtering much of the harmful light, the visual system is more relaxed and this prevents eye fatigue, especially in people who spend 8 hours in front of a screen.
- Anti-reflective treatment: it is a basic treatment so that the glass does not cover your eyes and the people around you can see your eyes clearly and not see the things around you reflected in your lenses.
- Hydrophobic treatment: this is a treatment on the glass that repels water that may adhere to the lens. For example, if it is raining, water drops touch the lens and automatically fall to the ground.
- Hardened treatment: a treatment that strengthens the glass to prevent breakage.
- Driving treatment: these are special filters that adhere to the lens and protect against light from oncoming cars. It is very useful for drivers.
- Anti-dirt treatment: prevents dust and dirt particles from adhering to the glass.
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