At the beginning of the novel, August says, "I won't describe what I look like. Whatever you're thinking, it's probably worse" (page 3). August, who suffers from mandibulo-facial dysostosis, does not want to disclose how he looks.
Via, his sister, provides some clues in her section of the book. She says that his eyes are halfway down his cheeks, about an inch below where they should be. She describes his eyes as downward-slanting, as if "someone cut [them] into his face" (page 88). The left eye is much lower than the right eye, and because his eye cavities aren't deep enough, his eyes bulge out. She also says that he doesn't have any eyebrows or eyelashes, and his nose is too large for his face. His head looks crushed on either side of his face, and he lacks cheekbones. Instead, he has deep fissures on either side of his face, making it look as if he had been burned and the skin had melted. From his many surgeries, he has scars on his face, including one large one from his upper lip to his nose. His jawbone is far too small, though he had a piece of his hipbone implanted in his jaw when he was younger. He can now keep his tongue inside his mouth and can eat and talk (he formerly had a feeding tube). He can also hear.
In Wonder, August' sister, Via, describes her brother for us.
August suffers from craniofacial abnormalities, and his facial deformity is still apparent despite countless operations. Via says that her brother's eyes sag below the level of normal eyes on a face. The left eye is also situated a little lower than the right eye. Because of shallow eye cavities, August' eyeballs appear unnaturally pronounced. The upper eyelids always appear half-closed, while the lower lids seem to sag downward.
August does not have any eyebrows or eyelashes. While his cheekbones appear to be non-existent, his nose seems to overwhelm his face. Via tells us that August has facial creases that run down both sides of his nose to his mouth, giving him the appearance of having suffered burns in a fire. His ears are also very small and cauliflower-shaped. Because of a severe overbite and an extremely undersized jawbone, August has had to endure surgeries to correct the shape of his palate. Via tells us that doctors implanted a piece of August' hip bone into his lower jaw during surgery. These surgeries have left scars on August' face, the most prominent of which is a gash from his upper lip to his nose.