Night Blindness: Symptoms and Diagnosis Explained

Q: Night Blindness: Symptoms and Diagnosis Explained

Hello Wei： If you find it difficult to read the signs outside at night, it may be related to your prescription. <br>Try wearing glasses to see if it improves your clarity; if it does, then there is likely no issue, and it should not be night blindness. <br>After examination, ever

Inquiry about night blindness?

Hello, doctor.
I would like to inquire whether not being able to see anything in a completely dark room could be a sign of night blindness.
Recently, I've noticed that I have difficulty reading signs at night, and I'm unsure if this is related to my myopia (one eye over 300, the other over 400) and astigmatism (one eye over 100, the other over 200), or if it could be night blindness.
I ride my bike normally.
At the end of January, I had a fundus examination and visual field test, and both doctors said the results were normal.
They also told me that based on these two tests, I do not have night blindness, and that I am just too anxious.
Thank you, doctor!

Wei, 20~29 year old female. Ask Date: 2021/02/19

Dr. Gao Pilin reply Ophthalmology

Hello Wei: If you find it difficult to read the signs outside at night, it may be related to your prescription.
Try wearing glasses to see if it improves your clarity; if it does, then there is likely no issue, and it should not be night blindness.
After examination, everything appears normal, so there is no need to worry.

The "dark adaptation time" is determined by the rod cells; "poor dark adaptation" refers to an extended adaptation time in lower light conditions, potentially leading to what is known as "night blindness," where one may not be able to see anything in complete darkness.
If you can see in dimly lit areas and can detect faint light in the dark without a prolonged adaptation time, it is likely not night blindness.

A definitive diagnosis of night blindness requires an electroretinogram (ERG) to measure the retina's response to light stimuli, recording the electrical changes in the retina to determine if there is a loss of function in the rod and cone cells.

At the E-Hospital in Puzi, Taiwan, the ophthalmology department is open on Monday, Tuesday, Thursday, and Friday mornings from 8:00 AM to 12:00 PM, and Wednesday afternoons from 2:00 PM to 4:30 PM.
Online responses can only serve as a reference; if necessary, you should visit a medical facility for treatment.
I hope to have the opportunity to serve you.

Best regards,
Gao Pilin

Reply Date: 2021/02/19

More Info

Night blindness, or nyctalopia, is a condition characterized by difficulty seeing in low-light conditions or darkness. It can be caused by a variety of factors, including retinal diseases, vitamin A deficiency, and certain genetic disorders. However, it is essential to differentiate between night blindness and other vision issues, such as refractive errors like myopia (nearsightedness) and astigmatism, which you mentioned in your inquiry.

From your description, it seems that you are experiencing difficulty seeing clearly at night, particularly when reading signs. However, you also noted that you have significant myopia and astigmatism, which can contribute to visual difficulties in low-light conditions. Myopia causes distant objects to appear blurry, while astigmatism can lead to distorted or blurred vision at all distances. Both conditions can be exacerbated in low-light situations, making it challenging to see clearly.

The fact that you have undergone thorough eye examinations, including retinal and visual field tests, and received confirmation from two ophthalmologists that there are no signs of night blindness is reassuring. These tests are crucial in diagnosing conditions affecting the retina and overall eye health. If the results were normal, it is unlikely that you have night blindness as a primary issue.

However, it is essential to consider other factors that might be contributing to your visual difficulties at night. For instance, the adaptation of your eyes to darkness can take time, and if you are in a completely dark room, your eyes may need a few moments to adjust. Additionally, glare from oncoming headlights or streetlights can also affect your ability to see clearly at night, especially if you have refractive errors that are not fully corrected with glasses or contact lenses.

If you are still concerned about your vision, it may be worthwhile to discuss your symptoms further with your eye care provider. They can evaluate whether your current prescription is adequate for nighttime driving or activities and whether any additional interventions, such as specialized lenses or treatments, might be beneficial.

In summary, while your symptoms of difficulty seeing at night could be concerning, the thorough evaluations you have undergone suggest that night blindness is not the issue. Instead, your refractive errors may be the primary cause of your visual difficulties in low-light conditions. It is always a good idea to maintain regular eye exams and communicate any changes in your vision to your eye care professional to ensure optimal eye health and vision clarity.

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