Low Vision Laboratory
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Research in the Low Vision Laboratory
Patients with eye diseases such as macular degeneration, diabetic retinopathy, and glaucoma are likely to lose critical areas of their vision progressively over time. These three diseases are the most common causes of visual impairment in aging populations, but they occur with some frequency in younger populations as well.
The “critical areas” affected by these eye diseases are those used to resolve fine detail while performing tasks like reading, and those used to detect larger objects in their visual landscape during activities like driving a car. The main goal of the Low Vision Laboratory at UIC is to develop scientifically-based strategies whereby patients with visual impairment are trained to maximize their remaining vision for tasks such as reading and driving.
Patients with eye disease may have small but healthy islands of remaining vision within severely diseased regions. We have developed a state-of-the-art laboratory with equipment aimed at identifying these islands.
The systems used for eye research in the laboratory are:
Functional Microperimetry System
Our laboratory has developed a system for functional microperimetry where precise measurements of functions like visual acuity can be measured at extremely small locations across the retina, the light sensitive tissue at the back of the eye, while simultaneously viewing the retina in real-time.
(see Figure 1)
This analysis is necessary to identify very discrete areas of remaining vision. Once the area is located, the patient may be trained to use it as a surrogate fixation area for reading. This is especially important if the normal area used to read, the fovea, has been ravaged by a disease such as AMD.
The output of this system is a map of visual acuity across the retina (see Figure 2) where brighter areas indicate healthy regions with good visual acuity and darker areas indicate less healthy regions with poor visual acuity.
Fig 1: Functional Microperimetry System
Fig 2: Output of Functional Microperimetry System for an RP patient
Multi-Focal ERG System
The mfERG system assesses the relative electrophysiological health of 103 discrete retinal locations using a non-invasive technique where a contact lens electrode is placed on the patient’s eye.
The measurements of electrical current across the retina are taken as the patient simply stares at a checkboard pattern that is flashed on a test monitor.
Fig 3: Multi-Focal ERG System
Fig 4a: ERG Output for Normal Subject
ERG System Test Results
The results of this test (see Figure 4a,b) provide the researchers with a map of the integrity of the retina. Where the results of the functional microperimetry system gives us an idea about the health of the retinal areas now, the mfERG results will give us some information as to the longevity of the site. By utilizing the results from these tests, we are able to identify a surrogate location for fixation training that could have lasting effects for the patient.
Fig 4b: ERG Output for AMD Patient
Driving Simulator System
One of the first questions that a patient with visual impairment asks their eye care professional about is whether or not they should drive. Driving is associated with independence and is often essential to maintain one’s livelihood.
We have developed a driving simulator system (see Figure 5) that provides patients and their clinicians with information about their abilities to perform driving related tasks.
Fig 5: Driving Simulator System
Driving Simulator Results
After driving an 8-minute test course on the simulator, we have developed a software system that analyzes 15 driving performance variables that are compared to those same variables measured for a group of age- and sex-matched normally sighted individuals.
The simulator variables are then input into mathematical models to compute the relative risk of having accidents for that patient. We can also develop a rehabilitation plan for the patient based on their performance on specific simulator measures.
Fig 6: Driving Simulator Screen
fMRI Evaluation of Brain Plasticity Following Low Vision Reading Rehabilitation
Functional Magnetic Resonance Imaging (fMRI) SYSTEM
The laboratory is currently studying the effectiveness of training patients to use these islands in order to read. We hope to improve this rehabilitation program by utilizing functional magnetic resonance imaging (fMRI). Imaging will be used as a tool to identify specific cognitive skills that can be acquired in the program and to identify potential brain activity patterns that are consistent with effective rehabilitation.
This research will provide critical information regarding the plasticity of the brain’s visual system in response to vision rehabilitation. Given the cost of rehabilitation services, it is necessary to determine which aspects of rehabilitation are truly effective in improving the recognition and motor skills necessary for reading and identification of objects in the environment. Knowledge of the brain’s response following different reading rehabilitation protocols will allow us to select the most appropriate program for individual patients.
Link to Center for MR Research
