Progressive impairment of visual capacity and driving
Diseases of the retina and optic nerve generally affect patients from 20 to 60 years of age. Senile macular degeneration, glaucoma and cataracts are suffered by older persons.
It is estimated that a diabetic person has a 20-40 times greater chance of losing his/her sight from cataracts, glaucoma, retinopathy and irreversible bilateral eye disease than the rest of the population.
Diabetic retinopathy should be suspected in any diabetic patient, even if he/she has good visual acuity, because it is the cause of 70-120% of blindnesses.
Degeneration of the retina
It is common in elderly persons, especially in the macular area, and often bilateral, although the extent to which each eye is affected may be asymmetrical. It impact on vision is very important because it may adversely affect central vision.
Senile macular degeneration
It is an incapacitating disease that causes changes in the ability to perform basic activities, and has a large impact on more complicated tasks such as driving. It is suffered by over 10% of persons older than 75 years.
They are yellowish deposits that do not usually cause symptoms but can be associated with a greater risk of developing neovascularization. They are diagnosed on routine funduscopic examination.
Disorders in vascular supply
They affect the optic nerve causing ischemic neuropathies that seriously perturb vision.
Inflammation of the posterior pole
This affects visual capacity due to cumulative effect of multiple relapses, as also occurs with hereditary degenerative diseases of the retina, diseases of the optic pathways such as neuritis and papillitis, demyelating diseases, toxic neuropathies caused by alcoholism and smoking, and retinal dystrophies.
Glaucoma is a disease characterized by an increase in intraocular pressure and excavation of the optic nerve disk, producing visual field loss. Progression of the disease can cause complete impairment of visual capacity.
The most common form of glaucoma is primary open-angle glaucoma or chronic simple glaucoma. It affects 1 in 200 persons over 40 and its prevalence increases with age. It often has no symptoms until it causes an important reduction in visual field. It is usually bilateral, but may progress asymmetrically.
It has been estimated that 2% of the population had an intraocular pressure (IOP) greater than 24 mm Hg and that is over 21 mm Hg in 5%.
However, only 0.5% have visual field loss, and therefore a diagnosis of glaucoma is not necessarily definitive. For this reason, an IOP of 21 mm Hg or greater only allows the disease to be suspected, especially if there is a discrepancy of more than 5 mm Hg between both eyes.
Persons with a family history of disease, such as myopics, diabetics and cardiovascular patients, have a greater risk of developing glaucoma. Although their IOP is normal, younger patients should have a checkup every two years and patients over 50 annually.
Eye pressure can be altered by certain drugs such as: anticholinergics, hexamethonium, amphetamines, reserpine, corticosteroids, and tricylic antidepressants. A tonometry should be performed periodically.
- The adverse events caused by any condition previously discussed result in tiredness and involve a serious risk for driving.
- The extensive, comprehensive study of every driver with reduced visual capacity, even if asymptomatic, enables the physicians to warn the patients of diseases that can cause a significant increase in the risk of driving.
- The physician, according to his criterion and experience, can decide to inform the patient about this risk for driving and commit him with self-care and treatment compliance with all necessary means, for the purpose of preventing as possible a future impairment.
- In diabetic retinopathy, the ophthalmologic review should be semiannual or annual depending on development and control of the disease, and the report on the evolution should be provided by the patient for obtaining the driving license and extension.
- Intraocular pressure over 22 mmHg warns about the presence of related risk factors and the need for maximizing the revisions for the loss of visual capacity that the specialist should also report in writing to the patient for obtaining the driving license and extension.
- The physicians should warn the patients about the risk o some drugs of affecting ocular pressure, carrying out periodic tonometries, and advising against driving while the patient has not eye pressure controlled.
- In many diseases, if there is no treatment and the disease progresses, the patient should be warned that the term of the license is shortened and the revisions should be more frequent, for his safety and that of all.
- Any progressive disease which does not allow for maintaining visual capacity in the limits established by the law, should be notified to the patient verbally and in writing with his limitations for driving, recommending him to provide the report for obtaining the driving license and extension.