Neuroophthalmology deals with defective vision caused by the so-called strabismus. It is a permanent or recurrent misalignment of the eyes.
What is neuroophthalmology?
Neuroophthalmology deals with defective vision caused by the so-called strabismus. Ophthalmology distinguishes between two forms of this defective vision: congenital and acquired. When a person squints, his or her eyes do not look in the same direction; instead, the gaze goes inward or outward, upward or downward. The symptoms can vary. There are patients with a noticeable defective vision, while in others it is hardly noticeable. Strabismus can occur unilaterally or alternately. Four million people in Germany are affected by this strabismus, both adults and children. Fifty percent suffer from amblyopia (weak-sightedness). A small proportion of four percent does not have sufficient spatial vision. This defective vision is called stereo vision.
Treatments and therapies
The eyes can deviate outward, inward, downward, upward, rolling, or a combination. If a person suffers from this misalignment of the eyes and squints as a result, the resulting images diverge so much that his or her brain can no longer combine these perceptions into a unified spatial image. This results in double vision. The patient perceives everything he sees twice. Children with defective vision do not see twice because the double image transmitted by the squinting eye is simply switched off by the brain. What at first appears to be a simple solution of nature is, however, by no means to be accepted as such, since the affected children develop an increasingly severe defective vision as a result of this process after only a short time. This defective vision, which develops in the eye that is switched off, is referred to in technical language as amblyopia. The earlier babies and toddlers are treated, the more effectively this defective vision can be eliminated or at least corrected to such an extent that those affected can live well with it. This defective vision can only be effectively treated in early childhood with conservative methods. The older a person is, the more difficult it is to correct this ametropia. Often, only a surgical intervention on the eye muscles can help. Ophthalmologists therefore advise parents to keep a close eye on their child in order to detect ametropia as early as possible. Increased caution is required if this strabismic ametropia has occurred in the direct family line in parents and grandparents. Side lineage such as parental siblings and their offspring should also be considered. Infants undergo ophthalmic-orthoptic examination for eye tremors, corneal opacities, strabismus, eye abnormalities, gray-white pupils, enlarged, light-shy eyes, and song changes. At six to twelve months of age, infants who are developmentally delayed, premature infants, and infants whose family history includes established eye disease are examined. At two to three years of age, all children suspected of having strabismus or general low vision are examined. This allows ophthalmologists to detect small-angle strabismus and an optical refractive error early. Patients of all ages are examined not only when there is a visible strabismus, but also when there are symptoms whose clinical picture cannot be clearly assigned at first: disturbances in motor function, frequent reaching out of one’s hand, unsteady gait, increased bumping and stumbling, rubbing and squinting of the eyes, head misalignment and double vision. Primary care physicians recommend that their patients seek specialist evaluation. Ophthalmologists and clinics provide advice regarding early education for children with visual impairment, for example, choosing a school for the visually impaired. In the case of employees with visual impairments, they refer them to the right contacts for vocational support centers and in-service services. They advise their patients on workplace equipment suitable for the visually impaired.
Diagnosis and examination methods
Neuroophthalmology draws on a variety of orthoptic examinations to diagnose strabismus. The individual steps include early detection of low vision and strabismus, treatment and therapy through glasses or patching, and achievement of binocular interaction.Contact lenses can compensate for astigmatism and high refractive error, presbyopia, irregular corneal curvature, keratoconus (continuous corneal curvature), iris defects and anisometropia with different image sizes on the retina. In addition to determining the refractive error, a topgraphic measurement of the corneal shape is performed. Magnifying vision aids and edge filter lenses can be a further aid to help the patient cope better with everyday life. If a patient has a visual defect that cannot be treated by conservative treatment options, the elimination of the strabismus is performed by eye correction using a surgical procedure on the eye muscles. Orthoptic diagnostics determines the visual performance in near and distance, monocular or binocular, checks the eye position and measures the squint angle. It checks the interaction of both eyes, gaze target and gaze sequence movements, and fixation. Special neuroophthalmologic examinations include the Ganzfeld electroretinogram (ERG), which reliably detects changes in the retina using electrodes placed on the locally anesthetized retina. To uniformly illuminate the retina, the pupil is dilated by eye drops. By examining visual evoked potentials (VEP), the sensory impressions received by the retina are converted into a current that is transmitted via the optic nerve to the visual center of the brain. This method measures the time it takes for the incoming light to travel from the back of the eye to the brain. For this purpose, electrodes are attached to the back of the head and the forehead. Furthermore, the ophthalmologist examines whether color and contrast vision are correct. The refractive error is always determined during the initial examination by administering pupil dilating eye drops. In this context, it is important to check the reading speed, as this ability is largely determined by the patient’s visual acuity or visual impairment. The worse the person’s vision, the more difficult it is for him or her to perceive written characters. However, orthoptic diagnosis and care do not focus solely on the eye disease, but also take into account secondary accompanying symptoms that are directly attributable to this visual disorder. This includes children and adolescents with behavioral and developmental problems as well as reading difficulties. Patients with acquired ametropia due to brain damage from accident or stroke with subsequent facial deficits are also included in this therapeutic approach.