Why are my new glasses so uncomfortable to wear?
Wearing new glasses is supposed to be clearer and more comfortable after wearing them, but there are still cases where new glasses are uncomfortable and feel awkward and different from the old glasses. However, when the newly-fitted glasses were tested, all technical indicators also met the requirements. What's going on?
1. The influence of the deviation between the horizontal distance of the optical center and the interpupillary distance
Under normal circumstances, the smaller the deviation between the optical center distance and the interpupillary distance, the better, so that the assembly is scientific and the wearer is comfortable.
If the patient's previous glasses had a large horizontal deviation in the optical center and the power was high, and the new glasses are equipped with the optical center positioned according to the standard interpupillary distance, they are likely to feel discomfort after wearing them, such as dizziness, bent vision, and the left and right eyes are less than one eye. In this case, the greater the diopter, the more obvious the reaction.
Therefore, when prescribing glasses for customers, you should first measure the deviation between the horizontal optical center distance and the interpupillary distance of the old glasses, and calculate the prism power corresponding to the pupil as a reference for choosing new glasses.
On the other hand, when viewing nearsighted objects, the eye muscles are often used to adjust, which can easily cause visual fatigue and increase the development of depth reading. The use of transitional light center distance is not suitable for older people. It is best to keep it in the original state to avoid discomfort and other problems.
2. The influence of the inclination of the frame body and temples
The inclination of the frame body and temples refers to the angle between the normal line of the mirror body plane and the temples. Generally, there are several specifications of 6 degrees, 8 degrees and 10 degrees.
Due to the many non-standard spectacle frames and the deformation of the spectacle frames during the wearing of spectacles, the influence of the inclination on visual habits is formed.
Because the position of the spectacle temples is mostly connected to the upper part of the spectacle frame, and due to the gravity of the spectacles themselves, the optical center position of the spectacle lenses shifts when worn.
For this situation, one solution is to allow the patient to adapt as much as possible. Another solution is to appropriately adjust the inclination of the temples to make it close to the original mirror when the patient cannot adapt.
3. Optical center asymmetry
For some patients with larger prescriptions and a longer history of wearing glasses, the asymmetry of the optical center of the old glasses will hinder the wearing effect of the new glasses.
When dispensing glasses, the optical center symmetry of the old glasses should be measured, and with reference to its diopter, the impact of the prism power at the corresponding pupil should be calculated. Lenses can be made according to the patient's old glasses condition.
This is especially important for some elderly patients, because it is not easy to change a long-term habit of wearing glasses.
These so-called substandard glasses are in line with the patient’s eyeball condition, and the patient will feel more comfortable and natural when wearing them.
For young patients with low prescription and a short history of wearing glasses, they should be allowed to wear glasses prepared according to the standard.
4. Effects of over-correction
Generally, the corrected visual acuity for myopia is required to reach 5.0. Over-correction will increase the amount of adjustment of eye muscles when looking at near objects, causing visual fatigue and further deepening of diopter.
Therefore, when the original glasses are over-corrected and the corrected visual acuity reaches 5.2 or higher, it should be adjusted to 5.0 when wearing new glasses.
In this way, some patients will feel discomfort due to the reduced diopter when wearing new glasses, such as difficulty seeing, etc. In this case, they can be adjusted to a normal state of 5.0 according to the actual situation.
5. The influence of lens curvature and astigmatism axis difference
A person who has worn 600-curve, -5.00D lenses for many years will find it difficult to adapt to 300-curve or even lower-curve lenses.
For glasses with astigmatism, the discomfort caused by the difference in astigmatism axis between the new lens and the old lens cannot be ignored.
Although the axial position of the new scope may be the position with the clearest vision, it is not necessarily the position that makes the patient comfortable.
Therefore, if the patient cannot adapt to the new axial position and it has little impact on corrected vision, the axial position can be maintained directly.
Problems with the product itself
1. Influence of lens material
Due to the differences in refractive index, light transmittance, Abbe coefficient and other performance indicators of optical white films, ultra-thin films, resin films and other materials, the wearing effect will be different for the same diopter.
For example, some people feel dizzy as soon as they wear ultra-thin tablets, but they feel no discomfort when wearing light white tablets.
2. The impact of the height of the nose pads of spectacle frames on visual effects
The height of the nose pads can directly affect the relative position of the optical center and the pupil and the distance from the rear apex of the lens to the cornea, which also affects the actual visual effect.
For hyperopia corrected by positive lenses, the effective refractive power of spectacle lenses to the eye increases as the distance from the rear vertex of the lens to the cornea increases, and decreases as the distance from the rear vertex of the lens to the cornea decreases.
For myopia corrected by negative lenses, the effective diopter of the spectacle lens to the eye decreases as the distance from the apex to the cornea increases, and then increases as the distance from the apex to the cornea decreases.
3. Spherical surface/aspherical surface, the influence of inner and outer non-surface
The image quality of inner non-lenses is better than that of outer non-lenses, so people who are used to spherical lenses may feel uncomfortable once they switch to outer non-lenses.