Delayed visual maturation (DVM) is an eye disorder found in newborn babies who exhibit poor visual behavior and attention. In the beginning, the infants seem as if they are unable to look at the mother’s or caregiver’s face or follow any objects with the eyes. On examination, the eye appears normal but fails to respond to stimulation such as a bright light or a threatening object. The infant will not blink when presented with a visual threat. Neurological tests are also normal, and DVM infants do not have nystagmus or wandering eye movements.
This condition is similar to cortical visual impairment (CVI) but with specific differences. In DVM, the vision problems resolve entirely as early as four to six months and as late as one year after birth. Vision returns to normal, unlike in CVI, where vision may return but not to normal levels. Besides, children affected by CVI have underlying neurological brain anomalies responsible for the abnormal vision.
DVI is usually associated with other delayed neurological development signs as well as infantile spasms. Treating the spasms improves vision in these children. A 2-4-month-old infant who lacks visual attentiveness should be taken to an ophthalmologist. Infants who do not pick up vision after six months may require additional examination because they may be having more severe eye conditions such as monochromatism or Leber's congenital amaurosis.
There are three types of DVM, and these are:
Infants present with normal general and neurological development, no systemic anomalies, and normal eye examination results. These infants can see within six to 12 months. Nevertheless, research indicates that they often exhibit delays in registering milestones in their development, such as sitting, walking, and speaking
DVM and systemic diseases or mental retardation
Some infants will have vision patterns that mimic the DVM type above. The visual effects are primarily because the infants are born prematurely with various intercurrent severe conditions. The illnesses include hypoglycemia, hydrocephalus, infantile spasms, hypocalcemia, brain malformations, seizure disorders, tuberous sclerosis, and Aicardi syndrome. These infants are affected by mental retardation that may come with seizures or without. Although vision improves, there are still some visual defects such as visual perception or eye and hand coordination. The infants hardly visually recover completely and experience slower visual development because of the neurological defects
DVM in association with other ocular diseases
The infants have nystagmus and other eye diseases such as albinism, optic nerve hypoplasia, and bilateral cataracts. Vision improvement for these infants is slower than for those in type 1. However, they register complete and faster visual recovery than those in type 2.
Causes & Risk Factors
DVM's causes remain unknown. However, the disorder is believed to be caused by a delay in the cortex's maturation in the brain. The delay in maturation of the cortical regions that provide object awareness ability, is said to be responsible. DVM may occur alone or may be associated with eye anomalies, neurodevelopmental abnormalities, and complications involving babies just before or after birth.
Signs & Symptoms
The primary sign of DVM is a lack of visual attention when the eye is presented with a stimulus.
Tests to determine DVM may include:
- A neurological examination and an ear, nose, and throat examination are needed
- Visual evoked potential (VEP), where the specialist tests to determine if the visual pathways are functioning and intact. If the VEP test is normal, the child has DVM, but which clears in about two weeks following the test. The infant may begin to respond to stimulation
- Additional testing such as using an electroretinogram (ERG), is required if the test results are abnormal. ERG helps to determine if the retina is functioning normally. Computed tomography (CT) and magnetic resonance imaging (MRI) can assess the brain’s structures. MRI and CT examinations are sure to differentiate between DVM and CVI
Infants with DVM and no other associated eye, neurological, or systemic conditions often have DVM resolving between 6-12 months of life.
Literature shows that frequently stimulating the infant can facilitate visual development. Stimulation includes holding visual objects with or without sound in front of the eye. Doctors suggest that parents can talk, feed, hold, or play with the infant, and these are the most important visual stimuli. Older children and siblings in the family can also get involved in activities to stimulate the infant's vision. If there is a need, visual exercises, speech therapy, and physiotherapy can stimulate vision.
Prognosis & Long-Term Outlook
Unless the infants are affected by other illnesses or conditions, DVM often resolves within six months. Some infants take up to one year to become visually attentive. Those extending that period need further examination for other conditions affecting them.
Prevention & Follow Up
Parents should also be counselled to remain patient as DVM will eventually disappear. Some infants take longer than others.