Why it may sometimes be hard to drive in the dark, even with new glasses?
Friday September 6th, 2019
Examination of functional vision helps to understand one’s own visual capabilities and can reveal latent diseases.
Good vision has traditionally been perceived as having good visual acuity. However, examining visual acuity only does not explain why it may sometimes be hard to drive a car in the dark, even with new glasses. This condition can be explained by decreased contrast vision, which may make it difficult to operate under dim conditions.
In addition to visual acuity, the examination of functional vision provides information on reaction time, contrast vision and the visual field – and only that way we can reach the core of the true visual capabilities of a person.
Eyeglasses can improve the visual acuity of a person who has a refractive error or a person with visual impairment. However, the person may still come across a situation where an object (such as a deer) may be overlooked in traffic due to the lack of vision.
– Vision is a critical part of a person’s ability to function. Good vision is not only sharp, but also clear, wide and fast. The latter three aspects have most often not been studied in a conventional eye examination, although they are even more important for road safety than visual acuity, says ophthalmologist Dr. Markku Leinonen, developer of the Ocusweep method, developed in order to measure functional vision.
Sustained visual health has a clear economic impact
Most people perceive vision as their most important sense. Good vision is a highway to learning for children. Deficiencies in vision make it difficult to explore the world and thus to learn. Further, maintaining vision is important throughout the whole life. It has a critical impact on people’s safe functionality, visual communication and the ability to work in different tasks and duties.
– The main task of health care is to keep people functional as well and as long as possible. Good vision is an essential part of human functionality and therefore should be monitored regularly. It has a significant impact on people’s quality of life and a smooth operation in their daily lives, as well as their ability to work in many areas. Measuring and monitoring people’s functional vision should therefore be the basis for decisions on how much money is spent in the prevention and treatment of various diseases, says Dr. Leinonen.
– For that reason, examination and monitoring of functional vision should be an integral part of both primary and occupational health, Dr. Leinonen continues.
Help and assistance for daily life and road safety
Functional vision is a key factor in many daily situations, such as road safety. Awareness of your own visual capabilities helps you to take into account the potential risks related to your possible limitations.
Slow reaction time should be considered in traffic with an increased safety margin to other cars, to allow enough time to react in situations that may happen all of the sudden. Reaction time refers to the speed at which the eyes, brain and hands interact, and the speed at which the information is processed in the brain. Reaction time may be practiced and improved, e.g. playing fast paced games.
Lack of contrast sensitivity, i.e. clarity of vision, may make it difficult to detect objects, because it becomes difficult to distinguish those from their background. That can make it difficult to detect e.g. that deer on the roadside when one is driving in rural areas. Twilight or poor weather conditions tend to add further challenges to those with low contrast vision. Deficiencies in contrast vision can be addressed e.g. by adjusting the lighting or using the correct type of lenses.
People rarely understand what they cannot see, because the brain tends to fill in the missing gaps (areas that the person really cannot see) along the time. The examination of visual field shows how well a person can see both horizontally and vertically. A person may have areas of obscurity (umbrages) in the visual field that are critical, e.g. in traffic.
– Personal awareness of possible problems is the first step for improvements in many cases. When a person is aware of his/her visual deficiencies, (s)he will be able to pay special attention to them. That way, many hazards in traffic can surely be avoided, Dr. Leinonen says.
Other medical conditions may be associated with problems in functional vision
Examination of functional vision does not necessarily reveal details regarding a person’s visual capabilities only. Some diseases, e.g. Alzheimer’s disease, may also decrease visual functionality.
– A brain tumor or cerebral hemorrhage can take up much of the visual field. In the future, Ocusweep may play an important role in the screening in addition to the monitoring of the vision. Currently, there are several interesting research projects underway to investigate the relationship between functional vision and various diseases, Dr. Leinonen explains.
In addition to optical stores, the Ocusweep method is also used in research in many important hospitals and universities, such as Turku University Hospital in Finland and Karolinska Institut in Sweden, for scientific reference. The diverse usages of this innovation range from assessing a person’s true driving ability to examining more serious illnesses and brain functions.
Mika Mahlamäki, Business Development Manager, Ocusweep