Certified Ophthalmic Technician (COT) Practice Test 2026 - Free COT Practice Questions and Study Guide

The DK value of contact lens material specifically measures the diffusion rate of oxygen through the lens material. It reflects how well oxygen can move through a given thickness of the lens, which is crucial for maintaining corneal health. A higher DK value indicates that the lens allows more oxygen to reach the cornea, which is beneficial for wearers as oxygen is essential for corneal metabolism and overall eye health.

This parameter is particularly important for soft contact lenses, where adequate oxygen permeability can prevent hypoxia, corneal edema, and other complications associated with prolonged lens wear. The "D" in DK stands for diffusion, while the "K" represents the permeability constant, making it a vital metric that pertains directly to comfort and safety for the wearer.

Understanding the DK value allows practitioners to choose appropriate lens materials that coincide with a patient's lifestyle and wearing habits, ensuring both fit and comfort while minimizing risks associated with lens wear.