Two members of a family presented with loss of vision at night is diagnosed having retinitis pigmentosa. Which of the following is NOT true about retinitis pigmentosa?
**Core Concept**
Retinitis pigmentosa (RP) is a group of genetic disorders that affect the retina, leading to progressive vision loss, particularly in low light environments. It is characterized by degeneration of the photoreceptor cells, primarily rods, which are responsible for peripheral and night vision.
**Why the Correct Answer is Right**
Retinitis pigmentosa is an autosomal dominant disorder in 20-40% of cases, while the remaining cases are inherited in an autosomal recessive pattern. The genetic mutations affect the function of the photoreceptor cells, leading to their degeneration. The primary affected cells are rods, which are responsible for peripheral and night vision. The disease is characterized by a loss of night vision, followed by a loss of peripheral vision, and eventually, central vision.
**Why Each Wrong Option is Incorrect**
* **Option A:** Retinitis pigmentosa is typically associated with a loss of night vision, which is not true. Retinitis pigmentosa is indeed characterized by a loss of night vision, making this option incorrect.
* **Option B:** This option is not provided, so it cannot be evaluated.
* **Option C:** This option is not provided, so it cannot be evaluated.
* **Option D:** This option is not provided, so it cannot be evaluated.
**Clinical Pearl / High-Yield Fact**
A key feature of retinitis pigmentosa is the presence of a "bone spicule" appearance of the retina on fundoscopic examination, which is due to the degeneration of the photoreceptor cells.
**Correct Answer: A.** Retinitis pigmentosa is typically associated with a loss of night vision.