This defect causes one eye to be weaker than the other, which results in the selection by the brain of the image from the stronger eye and its dominant role in the process of vision. The differences in seeing between the eyes may be small (below 0.5 diopters), as well as very large (>5 diopters). The basic treatment of the “lazy eye” mainly consists in doing more exercises for the weaker eye. However, we should not strain the weaker eye as it may get even weaker.
The preferable approach is to use the exercises for the correction of squint and eye convergence to improve the function of tracking and work of both eyes simultaneously, as well as the relaxation exercises to restore the balance between the brain spheres.
As based on my experience, to achieve the equal power of both eyes is not easy, especially if we use the glasses of different power and do vision exercises. The main problem is that the eye is doing practice for the whole day, so even if we were to increase the number of exercises for the weaker eye, the stronger eye would work for the most of the day, thus becoming even stronger.
Therefore, often miscellaneous methods of concealing the stronger eye, whether in full or its central part, are used. In such cases, the weaker eye can practice during the day. The only problem is that the concealing of the eye during our professional work and daily activities is not possible due to the lack of knowledge about these exercises among the public. Added to that, the full exclusion of the stronger eye creates the risk of different nature.
Therefore, it is preferable to use the method described here. Weaken the stronger eye using the glasses of the appropriate power. Assume that the eye defect is as follows: left eye (3 diopters), weaker right eye (4 diopters). For the exercises and the typical activities during the day, we can use the following lenses: left eye (1 diopter), right eye (3.5 diopters). With such option, the stronger left eye has to overcome 2 diopters, while the weaker right eye only 0.5 diopters. In his case, there is a good chance that the brain will choose our weaker eye more often, which in this way will be able to work during the day. The good thing about this method is also that the stronger eye is not completely eliminated from the process of vision as with the method of concealing. If your defect is not that advanced and fluctuates around -1 diopters, you should consider the power of +1 diopters for the stronger eye to encourage the brain to choose the stronger eye. Please beware of that during the first week you will have a feeling of discomfort but as soon as the brain responses to the change, your weaker eye will start to work as expected.
All the proposed methods for the defect of weak-sightedness (“the lazy eye”) should be used with care and moderation, adjusted to a particular person and his/her visual defect. You should also ensure that the power of lenses is adjusted appropriately to the defect of each of the eyes in the case of driving a vehicle or when doing a professional work where the factors of safety are fundamental.