Microphthalmia does not usually affect mental development in later life, and the two are not part of the same system.
Microphthalmia is a congenital developmental anomaly, which is characterized by a smaller than normal anterior and posterior diameter of the eyeballs, a narrow eyelid fissure, a small eye socket, and the eyeballs being deeply sunk in the eye sockets.
Most of the factors affecting mental development are related to neurological and brain disorders. Diseases such as congenital hydrocephalus, central nervous system malformations, and cerebral palsy are common disorders that affect mental development. Diseases of the eyeballs, digestive system or other organs of the body do not directly affect mental development, and there is no direct correlation between the two.
After discovering that you were born with small eyeballs, you should go to the hospital for examination and proper management under the guidance of your doctor.