In layman's terms Anophthalmia is the medical term that describes the complete absence of the eye from the orbit.
Microphthalmia is the term used to describe small eyes and it can range from barely noticeable to severe.
Severe microphthalmia is essentially the same as anophthalmia.
People usually use the terms Anophthalmia and Microphthalmia interchangeably but there are some differences.
Regardless of the differences, it is a very rare condition.
There are studies in England that have determined that 1 in 50,000 live births have this condition.
One of the hardest things about dealing with the condition is finding qualified physicians and other specialists.
Since the eyes are essentially an extension of the brain, the lack of development of the eyes may indicate that there are additional developmental issues that will need to be dealt with in the future.
Besides that, the eyes essentially help your skull maintain the shape of the face.
Without eyes, there's nothing preventing malformation of the skull as the child develops.
To prevent malformation of the face, children need to be fitted with "conformers" which are essentially place holders that help keep the skull from collapsing onto itself.
The conformers need to be replaced periodically as the child grows.
If you have a child born with Anophthalmia or Microphthalmia, please be aware that there is a small but very well connected network of other parents and institutes setup to help you.
Look up the AFB The American Foundation for the Blind and ICAN the International Children's Anophthalmia/microphthalmia Network, just to name a couple.
Make sure you talk to your state's disability services people as your child may be entitled to support to help out with their education and long term care.