The overall goal of the following experiment is to assess monocular and binocular dynamic vision functions, which are uniquely affected in optic neuritis patients, and may be used as quantitative non-invasive tools to assess the extent of myelination along visual pathways. This is achieved by applying the object from motion or OFM protocol at different velocities in order to define motion perception sensitivity in the tested eye as a second step. The time constrained stereo protocol is applied at different binocular disparities for one long constant stimuli duration to define the dependency of binocular visual functions on disparity.
Next, the time constrained stereo protocol is applied at different stimuli durations for one constant binocular disparity to define the dependency of binocular visual functions on stimuli duration, the results show that OFM and time constrained stereo protocols are sensitive tools that are uniquely affected in optic neuritis patients. Furthermore, these tests may be used as quantitative tools to assess the extent of myelination along visual pathways based on the correlation to VEP latencies is The main advantage of this technique over existing methods like static visual function, is that it's more sensitive to the visual deficit of optic neuritis patients. Furthermore, these protocols can be used to study ation and dilation over time.
This Method can help answer key questions in the neuro ophthalmology field, such as how can we explain the continuous visual complaints of optic neuritis patients following recovery of visual acuity? The implication of this technique extends toward therapy in multiple sclerosis because it's enables evaluating the efficacy of current and evolving therapeutic strategies targeting me nation in the CNS. To begin the training for the object from motion or OFM protocol, seat the subject 50 centimeters in front of the computer screen, then open the OFM software instruct the subject that she will be presented with motion defined objects, instruct her to respond as accurately and quickly as possible by pressing the A key and then verbally naming the perceived object.
Following each response. A screen indicating press, the space bar appears, instruct the subject to press the space bar. When ready to identify the next stimulus, explain to the subject that some stimuli will appear at hard to perceive velocities and other stimuli will appear at easier to perceive velocities.
Then enter learning OFM on the command line. The subject will now be presented with four example stimuli. Have the subject keep both eyes open for these learning trials.
After the subject presses A and identifies the object, press the left mouse button if the answer is correct, and press the right mouse button. If the answer is incorrect, Training phase is over. It's time to move on to the testing phase.
When ready to begin the OFM testing cover one eye of the subject with an eye patch, making sure that the eye patch covers the eye completely. Now enter OFM objects at the command line and choose one of the four stimuli sets. Each set contains 20 different objects.
Be sure to choose a different stimuli set every time the same subject is tested. Enter the subject's name tested I and tested date at the prompt. When ready to proceed with the test, have the subject press the space bar.
The stimulus is first shown at the slowest or most difficult to perceive velocity of four pixels per second. When the stimulus appears, the subject presses the A button and says the name of the presented stimulus. If the subject identifies the object correctly, press the left mouse button to signify a correct response.
After the subject triggers the next stimulus, it appears also at the slowest velocity stimuli continued to be presented at the slowest velocity as long as the subject continues to identify them correctly. If the subject fails to recognize an object at the slowest velocity, mark it as incorrect. With a right click, the object is displayed at six more steadily increasing velocities until either the subject correctly identifies the object or the fastest velocity of 24.5 pixels per second is reached.
Continue this procedure until all 20 stimuli in the set are either recognized or presented at the fastest velocity. Repeat the procedure for the subject's other eye using a different set of stimuli to begin the training. For the time constrained stereo protocol, seat the subject 50 centimeters in front of the computer screen and then open.
The stereo software instruct the subject that she will be presented with three dimensional shapes and is to name the perceived shape as accurately and quickly as possible. The shapes will be one of the following. A circle, a square, a triangle, or a star, explained the subject that some stimuli will appear in hard to perceive conditions and some will appear in easier to perceive conditions.
Have the subject put on 3D glasses and turn off the room lighting. Next, enter learning stereo at the command line. The subject is now presented with a 3D shape, followed by a 2D line.
Marking the shape's contour to make sure the subject has perceived the shape's, dimensions. After the subject names the shape out loud, press the key that corresponds with the answer given in this case a one for circle. The other three shapes are now shown first in 3D, then in 2D with the subject, naming them as they appear.
The subject is now presented with four repetitions of each 3D shape in random order presented at the longest stimulus duration of 500 milliseconds, and at the easiest binocular disparity of 840 seconds of arc. When the subject can successfully name the shapes the training is complete. Begin the binocular disparity testing protocol by entering stereo disparity at the command line.
Then enter the subject's name and testing date at the prompt. When the stimulus appears, the subject names the presented shape code, the subject's response by pressing the corresponding number key on the keyboard, the subject presses any key to continue to the next stimulus. Each shape is presented for 500 milliseconds in one of four different binocular disparity conditions, 100 2300, 540, and 840 seconds of arc.
The order of stimuli presentation is random. The second stereo testing protocol involves varying the length of presentation time for the four shapes begin by entering stereo duration at the line. As before, when the subject responds to the presented shape, enter a 1, 2, 3, 4, or five to indicate the verbalized response.
Each stimulus is presented for 40, 60, or 100 milliseconds at two binocular disparities. This graph shows the total object from motion or OFM scores obtained in patients affected eyes shown by black circles or their fellow eyes shown by gray circles and the eyes of controls shown by open squares. The dotted lines are drawn at plus minus 2.5.
Standard deviations from the controls mean the response score can range from zero meaning no stimulus was identified to 120, indicating that all 20 stimuli were identified at the lowest speed. The OFM scores of the affected eyes of optic neuritis patients were significantly lower than the scores of normally cited eyes. Both optic neuritis patients and controls indicated by black and gray symbols respectively demonstrate improved stereopsis perception as a function of increased disparity.
This graph shows stereopsis perception as a function of stimuli duration. As seen, the control's perception is independent of stimuli duration. Thus, 40 milliseconds is a sufficient time for healthy eyes to synchronize binocular information.
In contrast, the optic neuritis patients have significantly worse performance when stimuli are presented for 40 milliseconds compared with stimuli presented for 60 or 100 milliseconds. This may be explained by the fact that monocular demyelination generates delay between the information projected via the two eyes, challenging binocular integration in time for brief stimuli. When the subjective visual quality of life score is plotted against the patient's OFM score, the results indicate that impaired quality of life associates with impaired motion perception while better quality of life associates with intact motion perception shown.
Here are the OFM scores plotted against visual evoked potential or VEP latencies for the affected eyes and fellow eyes. As seen, OFM scores are correlated with VEP latencies for the affected eyes, but not for the fellow eyes of the patients. Once mastered, this technique can be done in 15 to 20 minutes if it's performed Properly after its development.
This technique paved the way for researchers in the field of multiple sclerosis to study dynamic visual functions in optic neuritis.Patients.
