Dim vision can be caused by an assortment of eye conditions, and patients should seek treatment if they notice dimming in their visual field. It can be a sign of an acute ocular condition that needs immediate treatment. An ophthalmologist can examine the patient, determine the cause, and recommend some treatments to address it. Patients with a history of vision problems should make sure their doctors know about it when they seek care for dimmer than normal vision.
Sometimes the issue is infection or inflammation in the eye and around the optic nerve. Inflammation of the eyelids and neighboring structures can also cause dim vision, as can a foreign body in the eye. The patient may also notice eye pain, headaches, and a discharge from the eye in these cases. Blurred vision can also occur, and sometimes swelling narrows the eyes to slits and makes it hard to see.
Macular degeneration, glaucoma, and cataracts are also associated with dim vision. It can onset slowly, but patients may not notice the problem until it becomes quite severe. The gradual visual changes may happen at a rate the patient can adapt to, until significant vision loss has occurred and the dimming vision becomes unavoidable. Some patients also have low or dim vision as a result of conditions that interfere with the perception of color.
Another potential cause is a tumor in the brain, usually close to the optic nerve. The tumor can put pressure on the nerve and interfere with the signals it sends, causing the vision to appear dim. In this case, dim vision can onset quite suddenly, as the patient may not notice a change until the tumor is big enough to push on the optic nerve. Such people may also experience headaches and cognitive impairments.
When a patient reports to the doctor with dim vision, the first step is often to look inside the eye for signs of damage. If there is an apparent problem with the eye, the doctor can determine what it is and treat it. For conditions like glaucoma, treatment options primarily arrest damage and will not fix existing eye problems. It is important to get regular screening for glaucoma so patients can access medication before substantial vision loss occurs. If the doctor cannot find anything wrong with the eye, the next step may be to conduct some medical imaging studies of the skull to look for irregularities around the optic nerve.