Losing a contact lens is frustrating and raises the question of whether wearing the remaining lens temporarily is acceptable until a replacement arrives. While possible, it is not recommended due to the immediate impact on your visual system and overall safety. Wearing only one lens introduces an imbalance that forces your eyes and brain to work harder, leading to discomfort and impaired performance in daily tasks. The potential for temporary discomfort and functional limitations outweighs the convenience of maintaining clear vision in just one eye.
Immediate Safety and Comfort Concerns
Wearing a single contact lens when both eyes require correction creates induced anisometropia—a significant difference in refractive power between the eyes. The corrected eye has a clear image, while the uncorrected eye has a blurry image. The brain struggles to fuse these two disparate inputs into a single, cohesive picture. This constant struggle demands extra effort from the visual system, quickly leading to visual fatigue and eye strain.
This excessive visual effort frequently results in tension headaches, especially after prolonged focus. The body may also unconsciously attempt to compensate for the visual imbalance, which can manifest as an awkward head tilt or neck strain. Although wearing only one lens does not increase the risk of eye infection, the physiological cost to comfort and visual balance is substantial.
Functional Limitations and Driving Safety
The most significant consequence of wearing only one contact lens is the severe compromise to binocular vision—the ability of both eyes to work together as a synchronized pair. Binocular function is responsible for stereopsis, or depth perception, which is the ability to accurately judge the distance and spatial relationship between objects. When one eye is clear and the other is blurred, the brain loses the precise input needed to calculate three-dimensional space, effectively shifting vision to a monocular state.
This loss of accurate depth perception makes common activities more difficult and potentially unsafe, such as navigating stairs or catching objects. Driving presents a particularly high risk because judging the distance to traffic, pedestrians, and road signs is paramount for safety. Studies show that driving under simulated monocular conditions can significantly increase the risk of collision and slow reaction times when responding to hazards.
It is advised against driving with only one contact lens, especially if the uncorrected vision falls below the minimum visual acuity standards required by local regulations. These regulations often require at least 20/40 vision in the better eye. Even if the minimum is technically met, the impaired depth perception and slower reaction time create a safety hazard. It is safer to avoid operating a vehicle until you have corrected vision in both eyes.
Recommended Actions After Losing a Lens
When a contact lens is lost, the most practical and immediate step is to remove the remaining lens and switch to backup prescription eyeglasses. Eyeglasses provide balanced, corrected vision to both eyes simultaneously, instantly eliminating the visual fatigue and depth perception issues caused by monocular correction. Having a current pair of glasses is the best safety net for any situation where contact lens wear is compromised.
Once you have switched to glasses, contact your eye care provider or lens supplier to initiate the replacement order. Be prepared to provide your current contact lens prescription details to ensure the correct lens is ordered quickly. Do not attempt to salvage an old, expired, or damaged lens from a previous set just to complete the pair, as this risks eye irritation or infection. Temporary use of glasses is the recommended solution to maintain visual comfort and safety until your new lenses arrive.