Receiving a new pair of eyeglasses should mark the beginning of clearer vision, but sometimes the experience is met with unexpected discomfort and visual confusion. When the world still seems blurry or distorted, it is important to distinguish between the temporary period of adaptation and a true error in your lenses. This guide will help you identify the specific symptoms that signal a problem and provide a clear path for correcting a potentially inaccurate prescription.
Signs Your Prescription Might Be Incorrect
An incorrect prescription often manifests through severe and persistent physical symptoms that go beyond simple blurriness. One common indicator is the onset of frequent or intense headaches, which result from the eyes and brain overcompensating to force an out-of-focus image into clarity. This constant strain can present as a dull throbbing pain around the temples or forehead, especially after prolonged use.
Certain visual phenomena are strong signs of an error, such as a severe “fishbowl effect,” where straight lines appear noticeably curved or warped, or when depth perception is distorted. Incorrect lens power or alignment can also trigger dizziness, nausea, or vertigo, as the brain struggles to process the misaligned visual input. Furthermore, double vision (diplopia) while wearing the lenses almost always points to a significant refractive or prismatic error that must be addressed immediately.
Normal Adjustment Versus Prescription Error
Distinguishing between a temporary adjustment period and a genuine prescription error relies heavily on the type, severity, and timeline of the discomfort. When a prescription is new, particularly if the power has changed significantly or if you are switching to a complex lens design like a progressive lens, the brain needs time to recalibrate. This adaptation commonly causes mild, transient symptoms like slight eye strain, minor blurriness, or a feeling of being slightly off-balance. These normal adjustment symptoms should noticeably lessen each day, typically resolving completely within two weeks of consistent wear.
In contrast, symptoms caused by an incorrect prescription do not follow this pattern of daily improvement; they tend to remain severe, intensify, or persist well beyond the two-week mark. If your symptoms are so debilitating that they prevent you from wearing the new glasses for more than a few hours, it is likely a fundamental mismatch between the lens and your visual needs.
Where Prescription Errors Originate
Errors that lead to an inaccurate pair of glasses can occur at several points, beginning with the eye examination itself. The optometrist or ophthalmologist might obtain an inaccurate reading if the patient is fatigued, or if day-to-day vision fluctuations—perhaps due to dry eyes or blood sugar variations—influence the refraction test results. Human error during the subjective refinement of the prescription using the phoropter remains a possibility.
Fabrication and Measurement Errors
Once the prescription leaves the exam room, additional errors can be introduced during the fabrication process. The lens laboratory may mistakenly grind the wrong lens power, transpose the cylinder axis, or incorrectly measure the pupillary distance (PD). The PD, the precise measurement between the centers of your pupils, is a common source of error that causes significant eye strain if the optical center of the lens is misaligned. Simple administrative mistakes, such as a transcription error or a typo during data entry when ordering the lenses, can also result in the wrong numbers being sent to the lab.
Steps to Take When You Suspect an Error
If you determine that your symptoms are not resolving after the expected adjustment period, the first step is to temporarily stop wearing the new glasses and revert to an older, comfortable pair if possible. Immediately contact the office of the prescribing eye care professional (optometrist or ophthalmologist) to report the persistent issues. Most providers and optical shops offer a remake or warranty period, often 30 to 90 days, designed to cover these situations.
You will typically be scheduled for a re-evaluation, where the doctor will compare the original prescription against the lenses using an instrument called a lensometer. This verification process confirms if the lenses were manufactured correctly to the written specifications. If the lenses match the prescription but you still cannot see clearly, the doctor will likely perform a re-test, or “re-refraction,” to determine if the prescription itself needs to be modified. Understanding the provider’s remake and warranty policy is important, as it may cover the cost of a new exam and a new set of lenses if an error is confirmed.