Cataract vision
(simulation)

Cataracts are a common cause of visual disturbances in the adult population. The slow, progressive opacification of the crystalline lens of the eye distorts the optical passage of light to the retina resulting in diminished visual acuity. Cataract formation can be accelerated by a number of conditions, including injury, exposure to radiation, gout, certain medications (steroids), and the presence of diabetes mellitus.

Glare, particularly during night driving in the face of oncoming headlights, may be an early symptom of cataracts. Glare, diminished overall acuity, contrast and color resolution are compounded by the light-scattering effect of the cataracts.

Treatment for cataracts is surgical removal and placement of an intraocular lens.

Glaucoma vision
(simulation)

Glaucoma can cause deficits in peripheral vision. The abnormal regulation of intraocular pressure can result in gradual progressive atrophy of optic nerve cells. The development of chronic elevated intraocular pressure is generally painless, and the gradual loss of peripheral visual field can progress significantly before symptoms are noticed.

Glaucoma may also affect a number of subtler visual functions, such as redirection of visual attention, night vision, and color vision. With glaucomatous damage, Snellen acuity test results may not be affected, but peripheral field test results may show deficits. Specialist examination may result in early detection and treatment before the occurrence of possibly disqualifying vision loss.

Vision loss caused by glaucoma cannot be restored.

A therapeutic goal is to lower intraocular pressure to a level that preserves the existing neuronal cells and prevents further loss of the peripheral visual field deficit. Strict and ongoing compliance with prescribed ophthalmic preparations is required for successful treatment; however, antiglaucoma agents may have side effects that impact vision and interfere with safe driving.

Maculopathy vision
(simulation)

Macular degeneration is a leading cause of untreatable legal blindness in the United States. Macular degeneration describes many ophthalmic diseases that impact the macula function and interfere with detailed, central vision. These diseases increase in prevalence with age, affecting some 30% of all Americans by age 70. For the majority of cases, macular degeneration is a slow process resulting in subtle visual defects; however, approximately 10% of cases are a "malignant" form of the disease and cause rapid loss of central vision.

Peripheral vision is generally spared in macular degeneration. Therapeutic options are limited.

Macular degeneration causes noticeable signs and symptoms. Visual acuity drops, recovery from bright lights is lengthened, and eventually a partial or total scotoma develops in the direction of attempted gaze. Snellen-type acuity testing will detect diminishing central acuity.

Telescopic lenses redirect unaffected peripheral vision to compensate for lost central acuity, resulting in a reduced peripheral field of vision. The use of telescopic lenses is not acceptable for commercial driving.

Retinopathy vision
(simulation)

Noninflammatory damage to the retina of the eye has many causes. The most common cause of of retinopathy is diabetes mellitus. Background retinopathy with microaneurysms and intraretinal hemorrhages is common after 5-7 years with diabetes mellitus. In many cases, the retinopathy does not progress beyond this stage; however, fluid leakage near the macula (diabetic macular edema) can create partial scotomas in central vision or cause gross hemorrhage in the eye which can obscure vision and eventually lead to retinal detachment and blindness. Subtler visual modalities such as contrast sensitivity, flicker fusion frequency, and color discrimination may also be affected.

Strict control of blood glucose, as well as medical control of comorbid diseases (e.g., hypertension, renal disease, cardiac disease), may prevent or delay development of retinopathy.

Medical guidelines for the driver with diabetes mellitus include:

• Annual medical examination.
• Annual ophthalmologist or optometrist eye evaluation.
• Disqualification for a diagnosis of unstable proliferative retinopathy.