**Core Concept**
Aniseikonia is a condition where there is a significant difference in the perceived size of images between the two eyes. This can lead to difficulties in binocular vision and depth perception. The treatment of choice aims to correct this disparity and improve visual comfort.

**Why the Correct Answer is Right**
Contact lenses are the preferred treatment for aniseikonia because they can be customized to match the prescription needs of each eye, thereby minimizing the size difference between the two images. This allows for better binocular vision and depth perception. Contact lenses can also correct refractive errors, such as myopia or hyperopia, which may be contributing to the aniseikonia.

**Why Each Wrong Option is Incorrect**
**Option A:** Orthoptic exercises are a treatment for strabismus (crossed eyes) and other binocular vision disorders, but they are not effective in correcting aniseikonia. Orthoptic exercises focus on improving eye movement and coordination, but they do not address the underlying difference in image size.
**Option B:** Spectacles can be used to correct refractive errors, but they do not address the aniseikonia itself. In fact, glasses can sometimes exacerbate the problem by making the images appear even more different between the two eyes.
**Option C:** Surgery is not typically used to treat aniseikonia. While surgery can correct refractive errors or strabismus, it is not a suitable treatment for aniseikonia, as it does not address the underlying difference in image size.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that aniseikonia can be a symptom of a more underlying condition, such as strabismus or a significant refractive error. Therefore, a thorough ophthalmological examination is necessary to identify the root cause of the aniseikonia and develop an effective treatment plan.

✓ Correct Answer: D. Contact lens.