What common sequela may occur due to lens instability?

Lens instability can lead to retinal detachment as a common sequela because any movement of the lens can disturb the architecture of the eye, particularly the vitreous body and its attachment to the retina. When the lens is not stable, it can cause traction on the vitreous gel. This traction may lead to tears or holes in the retina, allowing fluid to accumulate beneath the retina and ultimately causing it to detach from the underlying layers.

In contrast, corneal opacity is usually related to conditions affecting the cornea itself, such as inflammation or edema, rather than lens stability. Increased intraocular pressure is more commonly associated with conditions like glaucoma and does not directly relate to lens position. Similarly, optic nerve damage could occur due to multiple reasons such as increased intraocular pressure or vascular issues but is not a direct consequence of lens instability. Thus, the primary concern associated with lens instability is the risk of retinal detachment, making that the correct answer in this context.