**Core Concept**
Fuch's heterochromatic iridocyclitis (FHIC) is a rare, chronic form of iridocyclitis characterized by heterochromia of the iris, particularly in the context of uveitis. This condition is often associated with Fuch's heterochromic iridodonesis, which is a condition where the iris becomes mobile due to the loss of iris sphincter and dilator fibers.

**Why the Correct Answer is Right**
Fuch's heterochromatic iridocyclitis is indeed associated with the Amsler sign, which refers to the presence of a heterochromic iris with an irregular shape and a mobile, non-reactive pupil. The condition typically presents with heterochromia, where one iris is lighter or darker than the other, often accompanied by a unilateral or bilateral uveitis. The pathophysiology of FHIC involves the destruction of iris sphincter and dilator fibers, leading to the characteristic signs of the condition.

**Why Each Wrong Option is Incorrect**
**Option B:** Posner-Schlossman syndrome, also known as glaucomatocyclitic crisis, is a condition characterized by recurrent episodes of low-pressure glaucoma, uveitis, and corneal edema. While it shares some similarities with FHIC, it is not associated with the Amsler sign.

**Option C:** Uveal-effusion syndrome is a rare condition characterized by the accumulation of serous fluid in the uveal tract, leading to uveal effusion and secondary glaucoma. It does not exhibit the characteristic signs of FHIC, including heterochromia and iris mobility.

**Option D:** None of the above is incorrect, as Fuch's heterochromatic iridocyclitis is indeed associated with the Amsler sign.

**Clinical Pearl / High-Yield Fact**
FHIC is often considered a milder form of uveitis, with a favorable prognosis and minimal vision loss. Recognizing the characteristic signs of FHIC, including the Amsler sign, is essential for distinguishing it from other forms of uveitis.

**✓ Correct Answer: A. Fuch heterochromatic iridocyclitis**