The cardinal findings of Neuhauser syndrome, also known as MMR syndrome, are impaired intellectual development or developmental delay, megalocornea, hypotonia, prominent forehead, micrognathia, prominent nasal bridge, and thin upper lip or carp-like mouth (Naritomi et al., 1997). Reviews Gutierrez-Amavizca et al. (2013) reviewed published reports and tabulated the clinical features of 35 patients with Neuhauser syndrome. Primary megalocornea and psychomotor delay were present in all patients. Characteristics observed in more than half of patients included hypotonia, growth retardation, abnormal electroencephalography (EEG) and/or seizures, micro- or macrocephaly, brain malformations such as cerebral atrophy and hypoplastic corpus callosum, craniofacial dysmorphisms, cardiac anomalies, osteoarticular abnormalities, and refractive errors. Additional features found at low frequency included primary hypothyroidism, recurrent infections, feeding difficulties, cerebral hypomyelination, dyslipidemia, sensorineural deafness, laryngomalacia, large fleshy and cup-shaped ears, obesity, and cryptorchidism. The authors stated that the classification suggested by Verloes et al. (1993) did not seem to be applicable, and proposed that the diagnosis of Neuhauser syndrome should be made in the presence of intellectual disability and megalocornea in the absence of elevated intraocular pressure, with at least 1 minor feature from among those observed in more than half of patients.

Isolated congenital megalocornea is a genetic, non-syndromic developmental defect of the anterior eye segment. The disease has characteristics of bilateral enlargement of the corneal diameter and a deep anterior eye chamber, without an elevation in intraocular pressure. It can manifest with mild to moderate myopia as well as photophobia and iridodonesis (due to iris hypoplasia). Associated complications include lens dislocation, retinal detachment, presenile cataract development and secondary glaucoma. There is evidence this disease is caused by mutation in the CHRDL1 gene on chromosome Xq23.