Increased volume of blood in the conjunctival vessels results in an increased appearance of redness. Red eye may be due to a number of different reasons. Also see CLARE.
These types of lenses can be made from various different rigid plastic materials, formerly PMMA (Dk = 0) but now materials with higher gas permeability are commonly used. These lenses are highly customizable, allowing the practitioner to adjust and fine-tune a number of lens parameters to best fit the patient. Because of this, these lenses are well suited for patients with high corneal astigmatism or keratoconus. Because of higher silicone content, these lenses tend to be very hydrophobic, therefore in addition to a disinfecting solution these lenses would also require an application of a wetting agent prior to insertion to increase comfort of wear. These lenses are typically called “RGPs” or “hard contact lenses”.
An iodine derivative of fluorescein which binds to mucus and cellular components. It is useful in the diagnosis of dry eye, in which it is seen binding to degenerated cells on the corneal surface. This dye often stings on insertion.
Toric lenses require a method of maintaining a fixed rotational position on the eye as the lens interact with the eyelid. This can be achieved by making the inferior portion of the lens thicker and heavier, using gravity to keep the lens stabilized vertically. Another way stability can be achieved is by making the superior and inferior portions of the lens thinner, and temporal and nasal portions thicker. In this design, the eyelid would sweep over the superior and inferior portion of the lens and exert pressure on the temporal and nasal regions to stabilize the lens horizontally
Placing the lens in the palm of one hand, place a few drops of multipurpose solution onto the lens. Next, use the index finger of the other hand and gently apply pressure, starting at the center of the lens and dragging the finger towards the edge in various directions. Flip the lens over and repeat this process. This is typically done to aid cleaning by removing the initial protein and microorganism load on the lens.