**Core Concept**
Complete unilateral congenital cataract refers to a lens opacity in one eye present at birth, which can cause amblyopia (lazy eye) if left untreated. The goal of early surgical intervention is to restore vision and prevent permanent visual impairment.

**Why the Correct Answer is Right**
Surgery for unilateral congenital cataract should be performed as soon as possible, ideally within a few weeks of birth. This early intervention is crucial to allow the brain to develop normal binocular vision and prevent amblyopia. Delaying surgery beyond the neonatal period can lead to permanent vision loss. The developing brain is most plastic during this period, making it an ideal time for surgical correction.

**Why Each Wrong Option is Incorrect**
**Option B:** Waiting until 6 months of age may result in significant visual deprivation and increased risk of amblyopia.
**Option C:** Delaying surgery until the age of 2 years can lead to permanent vision loss and decreased potential for binocular vision.
**Option D:** Postponing surgery until the age of 5 years is unlikely to restore normal vision and may result in lifelong visual impairment.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that early detection and treatment of congenital cataracts are critical to prevent amblyopia and achieve optimal visual outcomes.

**✓ Correct Answer: A. Within a few weeks of birth**