While many vision defect symptoms of Parkinson’s disease do not sound so severe when you read the list, the fact is that they are not as easily corrected as when they occur in people who do not have PD. Some problems are caused by characteristic PD symptoms while in other instances the problems may actually be caused by medication taken for primary symptoms. Although there is help for most of the issues, for some patients certain symptoms may not be easily treatable.
Using an fMRI, functional magnetic resonance imaging of the brain, scientists at Emory University School of Medicine focused on the somatosensory or visual cortex. Although these were tactile tests what they found was less activation of the somatosensory areas of the brains of PD patients than in healthy control subjects. Previous testing had already indicated the relation of the visual cortex to the sense of touch.
Two important things to note is that surgery is usually neither encouraged nor available and those glasses from the pharmacy or discount store are discouraged. There are prescription glasses which can be of value and other appliances which can aid desk and house work.
One of the most common complaints is blurry vision. Usually known as convergence insufficiency, blurred or double vision can be the result of lack of eye coordination. Diplopia is often a defect affecting near vision. Because PD patients often close their eyes involuntarily, eye coordination and double vision can result. There are beneficial exercises such as the Pencil Pushup, a manual exercise as well as computer exercises. Your neuro-ophthalmologist can even monitor your exercising from his/her office.
Double vision with one eye is uncommon in all but Parkinson’s disease. Monocular double vision is often a function of dry eyes or wet watery eyes. The cause is the degeneration in the brain stem due to lowered levels of dopamine cells, the neurotransmitters, whether in the brain or in certain retinal cells which transmit images to the brain. Often it is suggested that one eye be covered. This can be done in a creative variety of ways.
Focusing problems can also be the result of muscle stiffness of the focusing lens within each eye. It can slow or block the automatic focusing process and prevent its completion. The effect can be the same for the eye as it is for the gait, for example in a PD patient. Often adding astigmatism correction may be more feasible as well as comfortable than the constant head adjustment for reading.
It is important that the PD physician be consulted whenever the patient feels a significant vision issue arise. It may be especially helpful to locate an eye care specialist whether an ophthalmologist or optometrist with a working familiarity with Parkinson’s disease. There may be a neuro-ophthalmologists in your area who would certainly be the first choice for a Parkinson’s patient. The easiest ways to learn specialties is to ask. Ask before scheduling an appointment or ask other members of a local PD support group.
Vertical eye movement disorders and/or walking disorders make it difficult or impossible to look down to see the floor or ground. There are glasses for people missing the lower half of the visual field or unable to gaze downward. In these cases, two separate pairs of glasses are recommended, one pair for walking and another for desk-work. It is a nuisance and inconvenient but often the best solution.
Patients with poor balance, abnormal gait issues including shortening of stride and quickening of pace, foot drag or stumbling should probably not be walking while wearing bifocal or trifocal lenses. Instead it is suggested patients should be wearing no glasses or shatter resistant single vision lenses for the best view of the floor. However, other sources indicate that bifocal wearers actually demonstrated better comparative acuity than single lens wearers either because the “junction line” forces the wearer to “manually” adjust his gaze. Another possibility it because the line edge refracted light from wide beam to narrow beam. This would not be the case with bifocals or trifocals with varifocal lenses which graduate from one correction to another seamlessly.
Prism glasses can be very effective in many cases but “often, people with PD have varying visual convergence due to muscle control variations between the two eyes. This usually cannot be helped by fixed prism convergence correction.” per N.I.R.E.
It is important to be aware that most prism glasses are intended for desk work only and are meant to be worn only while seated. They should not be worn while walking, standing or going up or down stairs. Prism “down” lenses cause the wearer to perceive that he or she is walking uphill, an effect which increases as the prism is made stronger.
Visual acuity may change with medication on and off periods. Sometimes an adjustment in medications may cause an improvement. When the eye specialist is conducting an examination the readings can vary to an exam conducted just an hour later. Many eye specialists are unfamiliar with that phenomena. Parkinson’s patients have learned the need to be proactive throughout their treatment processes and this is another example. Some specialists will feel that the change in test results is muscular, some will attribute it to medications. Communication is essential and the examination must be scheduled to accommodate the specific requirements of a PD patient.
Parkinson’s disease patients often seem to stare because as the disease progresses they may not blink as often. The ability to blink is an important function because without the cleansing action which moisturizes at the same time an oily buildup can accumulate on the lens which causes tears to bead. This will result in blurred vision comparable to the beading process when water hits a waxed car. Left untreated the condition will aggravate the cycle. Artificial tears without preservatives are recommended and prescribed although it is often a matter of trial and error. Patients should not be discouraged to find that some may only work for a quarter of an hour. Cleansing solutions for the eye must also be used daily.
Reduced or poorer color vision (color deficiency) is another symptom which can develop with the progression of the disease. Seeing dim images because of reduced contrast and brightness as transmitted by the retina can be assisted if watching television or at the monitor by adjusting the contrast or brightness. Be sure to move your monitor away from a window as the exterior light may contribute to eyestrain.
Although there are eye exercises and pinhole glasses which prove effective for many people, they are not as effective for the issues facing PD patients. The exercises are worth a try but due to the ever changing conditions of PD, they may only provide temporary easing of symptoms if any.
Going green may also be less effective for Parkinson’s patients because of the fluorescent light subliminal flicker. Full spectrum incandescent lighting is probably the best bet for regular household activities.
There are several other vision aids available with prices ranging from a few to several thousand dollars.
CCTV Reading Magnifiers: desk located Closed Circuit TV print magnifiers up to 40X $$$$
Optical Print magnifiers: handheld and freestanding up to 6X
Electronic Print Magnifiers: handheld portable – to read box labels
Simple Magnifying glasses: inexpensive, lightweight – print held close to face
Telescopic Magnifying Glasses: hand focused to magnify distant print. Prices range from $25 to $3,500 for prescription magnifiers
Check the National Institute for Rehabilitation Engineering (N.I.R.E.) website for many creative solutions for vision issues.
There is no question that many PD patients are afraid to disclose their vision issue status. In an article by Susan Aldridge PhD published in Neurology on 11-28-06 she discussed Parkinson’s disease vision testing which included a distraction test similar to making a cell phone call while driving, 28% of the PD patients made driving errors compared to 16% of the control group. Those who made errors tended to have memory, vision and balance issues as well as daytime sleepiness. Contrary to expectations, patients with tremors were less likely to have their driving affected.
Often visual symptom problems are nystagmus, rapid, repetitive involuntary movements in one or both eyes which among other things can cause a person to lose their place on the page or screen when reading and ocillopsia, which is a jerking/swinging eye movement from eye misalignment. It has also been described as bouncing or wavy vision akin to losing the vertical hold on the television screen.
There is no question that vision problems are not only synonymous with quality of life issues as well as financial issues for both business and the individual. Vision issues are also a source of discomfort, stress, headaches and can result in additional injury.
GLOSSARY of EYE CONDITIONS
References for additional information:
Just for basic comparison and comprehension, check this WebMD site for a chart which shows what normal vision would see as compared to impaired vision