The serosanguinous fluid can appear pinkish in color due to the small amount of blood cells that mix with the serous drainage. The consistency of this exudate is watery and thin and typically appears during the healing of wounds.
Bifocals are often prescribed for presbyopia. Bifocals are eyeglasses that have two different prescriptions in one spectacle lens. The top part of the lens corrects for distance vision and the lower portion of the lens is designed to help a person see objects up close.
To conclude, a trifocal lens looks like a bifocal lens with the pill for near vision, only on the top of the pill, there is a band of 7-8 mm which contains the intermediary vision part. Trifocal lined lens vs. Bifocal lined lens. For you, this means that have only one eyeglass for all types of visions. The problem is that the vision parts, specially the intermediate one, are pretty narrow and to move the eye from one to the other diopters is difficult, making the adjustment harder.