OPTM3133 Lab Notes PDF

OPTM3133 Lab Notes Week 1 EOM, & Sensory Motor Evaluation Broad H test NSUCO test of fixation, pursuits and saccades Stereoacuity Worth Dot test Extraocular Motility, S...

OPTM3133 Lab Notes Week 1 EOM, & Sensory Motor Evaluation Broad H test NSUCO test of fixation, pursuits and saccades Stereoacuity Worth Dot test Extraocular Motility, Saccades and Pursuits Ocular Motility Test Broad H Test Purpose (Laymen) A method to test how well your eyes work together. Instructions given 1. Keep Your Head Still to Px 2. Focus and follow the pen torch as it is being moved up, down, left, and right, 3. Make sure to move Your Eyes Only Testing Distance 40cm Procedure 1. Remove the spectacle correction prior testing 2. Steady pace, begin at the midline 3. Move the pen torch in spherical manner among lateral sides 4. Go far enough laterally to make sure each muscle action is isolated (no sclera present) 5. Compare between the scleral show between both eye, look for under action or over action of yoke muscles 6. In children especially, place a hand on the child’s head to DISCOURAGE head movement so that eye movement can be assessed. 7. Look for under/overaction of testing muscle. Saccades and Pursuit Eye Movement Testing Saccades Purpose (Laymen) A method to test how well your eyes work together Instructions given to Px I will show a bird and clown. If I say bird look at the bird and if i say clown look at the clown. Testing Distance Standing position Distance - 40cm Examiner holds targets 10cm from the patients midline for horizontal saccades.  Examiner holds targets 10cm above and below the patient’s primary gaze for vertical saccades. Procedure Two fixation sticks used. NO instructions are given to the patient to move or not to move their head. The saccadic eye movements are observed and looked for any inability to complete five round trips, overshoot or undershoot from the target position, multiple re/fixations to look at the target, and for any head or body movements and graded according to NSUCO grading scale below. Direct observation of Pursuits Testing Pursuits Purpose (Laymen) A method to test how well your eyes can follow a moving object. Instructions given to Px Here I show you the bird, look at the bird and follow as I move it, don’t take your eyes off the bird. Testing Distance Standing position - 40cm Target is 10cm from the patient’s midline. Procedure Practitioner holds the target at the midline of the patient’s body and moves the stick in a circle or no more than 20 cm diameter; two rotations made in anticlockwise and two in clockwise. Patient is asked to follow the target. NO instructions are given to the patient to move or not to move their head. Observed for any inability to follow the target, fixation losses → refixations, head or body movements. Grade according to the NSUCO grading scale. Direct observation of Pursuits  Sensory Evaluation: Stereopsis & Worth Four Dot Test (WFDT) The Titmus Stereo or Stereo Fly Test Purpose This test measures how well your eyes work together at seeing depth and 3D images. General Information This test includes random pattern stereograms to overcome the problem of monocular clues. Like the Titmus test, the Randot test may be enhanced by using different test distances and by reversing the polarising lenses to change the disparities. Test performed at 40cm over the habitual correction/best corrected visual acuity and polarised glasses worn over the refractive correction. This test uses polarised 3D images. The test comprises of a suppression test, stereo fly, animal stereo and circles stereo test. Suppression Test: The letters “R” and “L” are seen only by the right and left eye respectively. CANNOT test for suppression monocularly. Failing to detect “L” indicates suppression of the left eye. Failing to detect “R” indicates suppression of the right eye. Gross Stereopsis: Use the random dot patterns. It tests two levels of disparity: 500 and 250 arc sec. These random dot patterns have NO monocular cues. Patient needs to identify shapes or letters they see in the squares. Stereo Fly Test: Useful for testing young children, who often respond behaviourally if the fly is seen in 3 dimensions. Pinching the wings above the plane of picture indicates the presence of gross stereopsis of 3552 arc sec. Pinching against the flat surface indicates absence of gross stereopsis and recorded as >3552 arc sec or no gross stereopsis present. Animal Stereo Test: Has 3 levels of testing for young children. Testing at 40cm. It tests three levels of stereopsis: ○ A-400 arc sec ○ B-200 arc sec ○ C-100 arc sec Circles Stereo Test (Wirth Test) Wirth circles tests fine depth discrimination. One circle among the three has a crossed disparity and must appear to stand forward from the other circles. Presents disparities from 800” to 40” at 40cm. A monocular patient can use the lateral displacement of the disparate circle to give a correct response, as far down as the 4th or 5th set of circles. Test is UNRELIABLE if used as a screening test for gross anomalies, unless you make your clinical judgements using circles 5 or 6-9. NOTE: Perform test in full light illumination, don't allow patient to view test without polarisers, uncrossed disparity measured by holding test plate upside down.  Variations to the Circle’s stereotest can be made finer by increasing the viewing distance. Standard Procedure With the polarised spectacles worn, disparities in the Animals test and Circles test are all crossed. With the Titmus test, the disparities may be reversed either by having the subject wear the spectacles upside down, or by holding the book upside down. If performance is poor in crossed disparity, test with the reversed disparity. If performance is markedly improved when the polarisation is reversed, the patient should be re-tested with the original orientation. Disadvantage of the Titmus stereotest is the displacement of some disparate circles seen monocularly, providing a possible clue for the patient who suppresses. This can be partially overcome by varying the orientation of the polarisers and ask the patient to report whether any circles are either “coming out closer” or “going further back”. Recording Results Worth Four Dot Test (WFDT) Purpose (Laymen) To test how well both eye coordinate. Tell me the number and colour of the dots you see. Procedure Performed at habitual distance and near correction. Use red filter in front of right eye and green filter in front of left eye. Switch on the far W4DT light after the filters are worn. Ask for the response and record accurately. Repeat the test for near and ask for the response. Record distance and near findings. Results Normal: 4 lights (1-R, 2-G, 1-W) OR (2-R, 2-G) OR (1-R, 3-G) Left eye suppression: (2-R) Right eye suppression: (3-G) Diplopia: 5 lights (2-R, 3-G) Crossed diplopia: 3 green on left side and 2 red on right side Uncrossed diplopia: 2 red on left side and 3 green on right side Recording of Results