Prescription eyeglasses correct refractive errors, such as nearsightedness, farsightedness, and astigmatism, using an exact calculation of lens power and axis. When new glasses fail to provide clear vision immediately, it can be confusing to determine if the issue is normal adjustment or an actual mistake in the prescription or lens fabrication. Understanding the difference between adaptation symptoms and signs of a true error is important for vision health.
Symptoms Indicating a Prescription Error
Persistent discomfort or poor visual acuity often points toward an incorrect prescription. An immediate sign is persistent blurriness that does not resolve after a few hours, especially at the specific distance required by the prescription (e.g., distance vision or reading range). When the eyes strain to compensate for the wrong power, it results in eye fatigue around the eyes after short periods of wear.
Frequent headaches are a common physical symptom because the visual system is forced to work harder to focus. Visual distortions, such as straight lines appearing curved or objects looking closer or farther away, strongly suggest an error in lens power or the cylinder axis for astigmatism correction. A power imbalance between the eyes or a prism error can cause diplopia (double vision) or a feeling of constant dizziness or motion sickness.
Distinguishing Normal Adjustment from True Errors
When wearing a new prescription, the brain and eyes must process altered visual information, a process known as neuro-adaptation. This temporary adjustment period is expected, especially with a significant change in lens power, new lens material, or a switch to progressive lenses. Mild symptoms are common, including slight dizziness, minor difficulty with depth perception, or the “fishbowl effect” where the peripheral view feels warped.
The normal adjustment timeline for most people lasts only a few days, but it can extend up to two weeks for those with a large change in prescription or who are wearing multifocal lenses for the first time. Symptoms that fail to improve or worsen after this 14-day window suggest an error in the prescription or the lens manufacturing. A practical self-check involves covering one eye; if the vision remains severely distorted or blurry, it may indicate a significant power or axis misalignment.
If the new glasses are intended for a specific task, such as reading, confirm that the required distance remains consistently clear without strain. Symptoms that include severe nausea, outright double vision (diplopia), or a pervasive feeling of imbalance after several days are not standard adjustment discomforts and warrant immediate attention. For complex prescriptions, like those with a high cylinder correction, the adjustment period may be longer, but the symptoms should still show gradual improvement.
Steps to Take When You Suspect a Mistake
Once symptoms persist beyond the expected adjustment period, contact the prescribing eye doctor or the optical dispenser. Clearly describe the specific symptoms and their duration to help determine the likely source of the problem. The next step involves having the lenses verified against the original written prescription, where the optical shop uses specialized equipment to check the power and alignment of the lenses.
If the lenses do not match the prescription, the issue is a fabrication error, and the optical provider must remake the glasses at no charge. If the lenses match the prescription but problems persist, the eye doctor must be contacted to schedule a re-test, which is often provided soon after the initial exam. Most optical providers offer a limited warranty or remake policy, typically ranging from 30 to 90 days, which covers manufacturing defects or prescription changes. Delaying action until after this warranty period has expired may result in the patient having to pay the full cost for new lenses.