Which condition is a progressive hereditary disease marked by night blindness and tunnel vision?

Which condition is a progressive hereditary disease marked by night blindness and tunnel vision?

• A. Retinitis pigmentosa
• B. Ophthalmoplegia
• C. Hyperopia
• D. Macular degeneration

Answer: (A)

Night blindness followed by gradual loss of peripheral vision points to a hereditary retinal dystrophy where the rods—the cells responsible for seeing in low light—degenerate first, with cone involvement later on. This pattern is classic for retinitis pigmentosa, a group of inherited conditions that progressively damage the retina. In retinitis pigmentosa, the initial impact on rods leads to difficulty seeing at night and reduced ability to detect movement. As the disease advances, peripheral vision narrows, producing tunnel vision. Because it’s genetic, there’s often a family history, and understanding inheritance is important for counseling. Typical findings support the diagnosis: a fundus exam may show bone-spicule pigment deposits in the mid-peripheral retina, along with narrowed retinal vessels and a pale optic disc. Functional testing like an electroretinogram usually shows diminished rod responses early on, with cone responses affected later. There’s no simple cure; management focuses on vision rehabilitation, safety strategies, and regular monitoring, with genetic counseling. Some discussions about vitamin supplementation exist but require medical guidance due to potential risks. Other choices don’t fit the pattern. Ophthalmoplegia involves weakness of eye muscles rather than retinal degeneration. Hyperopia is a refractive error that doesn’t cause progressive night blindness or tunnel vision. Macular degeneration affects central vision and typically occurs later in life, not with the night-vision loss and peripheral constriction seen here. The description aligns with retinitis pigmentosa.

Night blindness followed by gradual loss of peripheral vision points to a hereditary retinal dystrophy where the rods—the cells responsible for seeing in low light—degenerate first, with cone involvement later on. This pattern is classic for retinitis pigmentosa, a group of inherited conditions that progressively damage the retina.

In retinitis pigmentosa, the initial impact on rods leads to difficulty seeing at night and reduced ability to detect movement. As the disease advances, peripheral vision narrows, producing tunnel vision. Because it’s genetic, there’s often a family history, and understanding inheritance is important for counseling.

Typical findings support the diagnosis: a fundus exam may show bone-spicule pigment deposits in the mid-peripheral retina, along with narrowed retinal vessels and a pale optic disc. Functional testing like an electroretinogram usually shows diminished rod responses early on, with cone responses affected later.

There’s no simple cure; management focuses on vision rehabilitation, safety strategies, and regular monitoring, with genetic counseling. Some discussions about vitamin supplementation exist but require medical guidance due to potential risks.

Other choices don’t fit the pattern. Ophthalmoplegia involves weakness of eye muscles rather than retinal degeneration. Hyperopia is a refractive error that doesn’t cause progressive night blindness or tunnel vision. Macular degeneration affects central vision and typically occurs later in life, not with the night-vision loss and peripheral constriction seen here.

The description aligns with retinitis pigmentosa.