One eye can see clearly, but vision becomes blurry when both eyes are used together.

Under normal circumstances, being able to see clearly with one eye but experiencing blurred vision when using both eyes together may be caused by factors such as eye strain, refractive errors, or cataracts. Patients can receive appropriate treatment based on the specific cause. A detailed analysis is as follows:

1. Eye Strain

Prolonged use of the eyes—such as staring at electronic screens, reading, or driving—can lead to eye fatigue, making it difficult for the eyes to focus properly. It is recommended to limit eye usage time and apply warm compresses with a heated towel under medical guidance to relieve eye fatigue.

2. Refractive Errors

Improper eye use may trigger refractive errors, preventing the eyes from properly focusing light onto the retina, resulting in blurred vision. Patients are advised to use medications such as atropine sulfate ophthalmic gel or compound tropicamide eye drops under a doctor's supervision, while also managing their eye usage time.

3. Cataracts

If patients have systemic metabolic diseases such as diabetes, the structural integrity of the lens may be damaged, leading to lens opacity and symptoms such as decreased vision and blurred vision. Patients should use medications like phacolysin eye drops or pirenoxine eye drops under medical guidance. In severe cases, they should visit a reputable hospital for surgical treatments such as intraocular lens implantation or extracapsular cataract extraction.

Besides the three causes mentioned above, other conditions such as amblyopia, strabismus, or glaucoma may also be responsible. Patients are advised to seek timely medical attention for proper diagnosis and treatment.