If not retinitis pigmentosa, what is causing my temporary night blindness?
MAR 29, 2017
Question:
I am scared that I might have retinitis pigmentosa (a condition that changes how the retina responds to light, making it hard to see). I saw two different ophthalmologists in the last three months. Both examined my eyes, performed a visual field test and one even did a fluorescein angiography. Everything came out fine but I feel like my dark adaptation takes longer than it should and it makes me experience temporary blindness. For example, when I switch the lights off, I go blind for what seems like a very long time before I can distinguish anything in my bedroom, even with light passing through the curtains a bit. I am a 30-year-old female with high myopia (-7 and -8 diopters). What could be causing this?
Answer:
There are a number of reasons that you may be experiencing delayed dark adaptation, including the most likely, which is that you simply have a variation on the longer end of the normal dark adaptation time. In fact, it typically takes 20-30 minutes for dark adaptation to reach its maximum, depending on the intensity of prior light exposure. If you remain concerned, then there are formal electrophysiological tests, such as the ERG (electroretinogram) that are more sensitive than the testing you have had performed already.