Binocular Vision Presentation PDF

Stress Theory  Physics:  Stress represents the force that tends to deform the body.  Results in strain  Stress is the cause and strain is the result  General speech  We say we are “under stress”  Stress is still the effector  Stress Theory  Hans Selye...

Stress Theory  Physics:  Stress represents the force that tends to deform the body.  Results in strain  Stress is the cause and strain is the result  General speech  We say we are “under stress”  Stress is still the effector  Stress Theory  Hans Selye  Stress is the response  Stressors are the factors that produce the response  Definition:  “the non-specific response of the body to any demand made upon it.”  Emphasizes three factors  Stress is a response or reaction to something  The response can be produced by any agent, event or circumstance  The response is non-specific  Influences on Adaptation  Stress does not affect every person the same way  Stress does not produce the same response in the same individual at all times  Every individual has different stress tolerances  Interacting factors  Stressor variables  Type, persistence, intensity…  Concurrent conditions  Genetics, external factors (temp, pollution, noise)  Psychological factors  Personality and attitude  Prior conditioning Skeffington’s Model of Vision Centering Antigravity VISION Identification Speech-Auditory  Skeffington’s Four Circles  Antigravity System (Vestibular)  Basic frame of reference for orientation and spatial localization  Internal Balance and position in space  Centering (Convergence)  Directing body, head, and eyes toward area in space for information processing  Attention and orientation in external space  Skeffington’s Four Circles  Identification (Accommodation)  Gathering meaning from areas of selected attention in external space  Resolution, discrimination, differentiation, and determination of relationships between details  Speech-Auditory  Analysis and communication of what is seen  Nearpoint Stress Model  Skeffington  Humans are biologically unsuited for near-vision tasks imposed by society  The demands for sustained concentration, immobilization and mental effort provoke a stress response.  Characterized by a drive for the centering process to localize closer to the individual than identification.  Nearpoint Stress Model  For efficient reading  Vergence and accommodation need to localize at the plane of regard  The drive for vergence to localize closer than accommodation leads to blur or diplopia  This is the stressor!  Now what can we do????  Adapt!!!!  Nearpoint Stress Model  What are our choices?  1) Avoidance  Easiest solution to the problem as far as they are concerned.  2) Inefficient visual function  Might eventually lead to avoidance  3) Accommodative or vergence adaptation  i.e.-Accommodative or convergence insufficiency, COVD Quality of Life (QOL) Questionnaire  Developed by a COVD committee in 1995  Can be used to assess change via  Vision therapy,  Change in distance spectacle RX  Use of near point lenses  COVD Quality of Life (QOL) Questionnaire  Original version-30 questions  Shortened version-19 questions  Advantages of survey  Ease of administration  Low cost  Standardized  Disadvantage of survey  Leaves no room for elaboration by the clinician.  Parents versus Patients  Older children-patients  Younger children-parents and patients  COVD Quality of Life (QOL) Questionnaire  Scoring  “always”-4 points  “frequently”-3 points  “occasionally”-2 points  “seldom”-1 point  “never”-0 points  Total scores were obtained by summing the scores for each individual question  >20-indicative of a visual efficiency or perceptual disorder  How should you use it?  Cover Test  Cover test  Norms  Unilateral Distance: ◼ Used to detect strabismus ◼1 XP +/-2 ◼ If no movement, does this mean Near there is not a tropia? ◼4 XP +/-2  Alternating ◼ Used to detect phoria ◼ Used to assess amount of phoria and strabismus ◼ Does the exact amount really matter?  Phoria Measurement  Von Graffe  In phoropter  Used to determine lateral and vertical phoria  Must keep the letters clear at all times  This can be used interchangeably with the cover tests, right?  Norms  Distance  1XP +/-1  Near  2 XP +/-2  Near Point of Convergence  Assesses convergence amplitude  Objective and subjective test  Repetition is crucial  Both break and recovery will recede greater in patients with bv issues  Targets used  Accommodative- ◼ 5cm break, 7cm recovery  Penlight with red lens- ◼ 7cm break, 10cm recovery  Convergence Insufficiency  More likely to have reduced break and recovery  More likely to have reduced NPC with PL and red lens  Smooth Vergence  Assesses the amplitude of the fusional vergence response for both positive and negative fusional vergence.  Blur finding ◼ Accommodation ◼ How much convergence and divergence can be altered before accommodation is affected.  Break finding ◼ Fusional vergence free of accommodation  Recovery ◼ Provides information regarding the patient’s ability to regain fusion following diplopia ◼ How quickly and satisfactorily can a patient put the disrupted world back together again  Smooth Vergence  Skeffington (1969)  When blur is low the case is new.  When break is low the case is old.  When recoveries are low adaptation is poor.  Embedded vs. non-embedded  Its all about degrees of freedom!  Stereo Testing  Evaluate the degree and presence of stereopsis  Suppression check (R+L)  Local/Contour Stereopsis ◼ Wirt circles, Titmus stereofly and animals ◼ Uses two similar targets that are laterally displaced. ◼ Contains monocular cues ◼ Helps determine if peripheral stereopsis is present ◼ What should we shoot for?  Global Stereopsis ◼ Random dot stereopsis ◼ Helps to determine the presence of a constant strabismus  Prism Facility  Assesses the dynamics of the fusional vergence system and the ability to respond over time.  Measures vergence stamina  Akin to accommodative amplitudes and accommodative facility  What power to use? ◼ 8BO/8BI ◼ 12BO/3BI Age Norms ◼ 16BO/4BI 5-7 2.5cpm ◼ 12BO/6BI 8-10 5.0cpm 11-13 6.5cpm Young Adults 8.0cpm  Accommodative Testing  Amplitude  Push-up  Pull-away  Minus lens-to-blur  Facility  Monocular  Binocular  Response  Monocular estimated method (MEM)  Fused cross cylinder (FCC)  Other  NRA/PRA  Expected Values  Hofstetter’s Formulas  Based off of the work of Donders and Duane in the early 20th century.  Target was a single black line.  Minimum Accommodation  15-0.25(Age)  Average Accommodation  18-1/3(Age) Age (Years) Amplitude (D) 10 14.67 15 13.00 20 11.33 25 9.67 30 8.00 35 6.33 40 4.67 45 3.00 50 1.33 54 0.00  Accommodative Amplitude  Push-up vs. pull away  Materials:  Near point card or fixation target (tongue depressor with accommodative target affixed).  Accommodative Amplitude  Monitor patient response  Easier out of the phoropter  Watch for facial expression changes  Watch for the child that is not really looking!  Make sure the child does not back away from the target  Change letter size at 20cm and 10cm-NOT PRACTICAL!  Comparison to Hofstetter  Hamasaki-  106 subjects (212 eyes), ages 42 to 60 years  overestimation by 2D  Accommodative Amplitude  Minus Lens-to-Blur  Important Issue  Concerns about minification  Due to increasing the power of the minus lenses used  Solution??  Change testing distance to 33cm  2.50D still used in final calculation  ie. -6.00+|2.50| = 8.50D of accommodation  Expected values  About 2D less than the push up method  Accommodative Facility  Failure to clear minus  Accommodative Insufficiency  Convergence Excess  Minus causes an increase in esophoria with requires NRV to keep the target single  Failure to clear plus  Accommodative Excess  Convergence Insufficiency  Plus causes an increase in exophoria with requires PRV to keep the target  Accommodative Facility  What to record:  Does performance deteriorate with testing?  Starts off with quick changes but slows down over time  Does suppression occur and with which lenses?  Postural changes  Does patient slump in chair  Head tilt or turn  Patient complaints  Does patient attempt to move card?  Accommodative Facility  Norms  Developmental Trend upwards-  Why??? Age MAF BAF 6 5.5 +/-2.5 3.0 +/-2.5 7 6.5 +/-2.0 3.5 +/-2.5 8-12 7.0 +/-2.5 5.0 +/-2.5 12 and older 11.0 +/- 5.0 8.0 +/-5.0  Accommodative Posture  Monocular Estimated Method  Purpose:  To objectively determine a patient's accommodative posture or lag of accommodation  To determine the appropriate near vision Rx.  Select the appropriate M.E.M. card corresponding to a grade or reading level closest to that of the patient.  Card selected can be low demand (large print) or high demand (small print).  If too high of a demand-increase stress response-will lead to a higher minus response  Accommodative Posture  To verify the estimation  a neutralizing trial lens is interposed QUICKLY IN AND OUT, in front of one eye at a time, as the retinoscope light passes across the eye.  Lens speed is crucial  DO NOT hold the lens in front of an eye for greater than 1/5 of a second because the eye will have time to accommodate to the lens and/or binocularity may be disrupted.  Don’t forget to check both meridians for presence of astigmatism.  Accommodative Posture  Recording:  1. The power of the neutralizing lens used for each eye, including any astigmatism (with the axis).  2. Fluctuations or instabilities in the reflexes.  3. Rx used.  4. Reading level on MEM card used.  5. Distance used.  Expected Findings  Normal lag of accommodation is between +0.25 to +0.75 D.  Pass/Fail Criteria:  unequal reflexes  a lag greater than +0.75  any against motion (excessive accommodation)  Accommodative Posture  Lag of Accommodation  Focus is slightly behind the target  Accommodative Insufficiency  Convergence Excess  Lead of Accommodation  Focus is slightly in front of the target  Accommodative Excess  Convergence Insufficiency  Accommodative Posture  NRA/PRA  Indirect measure of accommodation  Binocular procedure  Set-Up  Patient is in the phoropter,  Wears his/her habitual reading Rx or distance refraction.  Target (20/30) line of letters is placed at 40cm.  Illumination is full  Accommodative Posture  Procedure:  The patient is instructed to report the first sustained blur.  Minus (PRA) lenses are introduced binocularly in 0.25 D steps until blur is reported.  After the blur is reported, give the patient a few seconds to ensure that it the letters remain blurred.  If they do not, continue the process until blur is constant.  Take away minus until the letters are once again clear  Repeat the process with plus (NRA)  Expecteds  PRA: -2.37 +/-1.00  NRA: +2.00 +/-0.50  AC/A Ratio  To determine the change on accommodative vergence that occurs when the patient relaxes or stimulates accommodation by a given amount  Is used to determine efficacy of plus at near  Calculated ◼ AC/A=IPD(cm)+NFD(m)(Hn-Hf)  Gradient ◼ Phoria measurement is repeated with either +/-1.00  Differences ◼ Calculated is typically larger than gradient ◼ Due to the effect of proximal vergence patients tend to under accommodate to a given stimulus (lag of accommodation) ◼ Lowers the result of the gradient method  Eye Movements  Fixation  Direct observation test  Patient is sitting  Binocular→→→→Monocular  SCCO Grading System  Fixate on a near accommodative target for 10s  4-Steady fixation-smooth and accurate  3-One fixation loss  2-Two fixation losses  1-More than two fixation losses.  Pursuit Testing  Northeastern State University College of Optometry (NSUCO)/Maples Oculomotor test  Direct observation test  Patient is standing  Procedure:  Target is moved clockwise and counter-clockwise two rotations.  Score depends on age and gender  Pursuit Testing  NSUCO grading  Ability  5-Completes 2 rotations in each direction  4-Completes 2 rotations in one direction only  3-Completes 1 rotation in either direction, but not two  2-Completes 1/2 rotation in either direction  1-Cannot complete1/2 rotation in either direction  Accuracy  5-No refixations  4-Refixations 2 times or less  3-Refixations 3 to 4 times  2-Refixations 5 to 10 times  1-No attempt to follow target or >10 fixations  Head/Body Movement  5-No head/body movement  4-Slight head or body movement (50% of time)  2-Moderate head or body movement at any time  1-Large head or body movement at any time  Saccade Testing  SCCO  Direct Observation  Patient is seated  Binocular→→Monocular  Procedure  Two target (20/60-20/80), 25 cm apart, 40 cm from patient  Targets are presented horizontally, vertically and diagonally  Grading  4+ smooth and accurate  3+ some slight undershooting  2+ gross over or undershooting or increased latency  1+ inability to perform the task or any uncontrolled head movement  Saccade Testing  NSUCO  Direct observation test  Patient stands  Two targets are held 20-25 cm apart.  The patient makes 5 round trips back and forth.  Grading is on ability, accuracy and body/head movement.  Comparisons are made based on age and gender.  Females-better younger  Saccade testing  NSUCO grading  Ability  5-Completes 5 roundtrips  4-Completes 4 roundtrips  3-Completes 3 roundtrips  2-Completes 2 roundtrips  1-Completes less than two roundtrips  Accuracy  5-No over or undershooting  4-Intermittent slight over or undershooting (50%)  2-Moderate over or undershooting noted 1 or more times  1-Large over or undershooting noted 1 or more times  Head/Body Movement  5-No head/body movement  4-Slight head or body movement (50% of time)  2-Moderate head or body movement at any time  1-Large head or body movement at any time  King-Devick Saccadic Test  Reading eye movements  Developmental growth  Procedure  Patient calls out 40 numbers horizontally  The lower the time→→→→the more efficient the eye movements  Grading  Based on the number of errors and time  King-Devick Saccadic Test  Three levels  Developmental Eye Movement Test (DEM)  Reading eye movements  Considered a visual-verbal test  Vertical array  Tests automaticity-the ability to automatically recall numbers  Horizontal array  Tests horizontal eye tracking  Grading is based on:  Number of errors  Types of errors  Time for each section  Horizontal time/Vertical time Developmental Eye Movement Test (DEM)  Four Possible Outcomes  No deficit in Ocular motility or automaticity  Ocular Motility Dysfunction  Normal vertical, High horizontal and ratio  Automaticity Problem  High horizontal and vertical, Normal ratio  Automaticity and OMD  Abnormal vertical, horizontal and ratio  Horizontal is worse than the vertical making the ratio high  Visagraph/Readalyzer  Objective test  Measures reading eye movements  Goggles contain infrared sensors that detect eye movement  Results are recorded and evaluated by a computer  Age normed passage-2 paragraphs long  Reading comprehension assessed.  Must get 7/10 questions correct unless not valid.  Visagraph/Readalyzer  Information determined and calculated  Fixations  Regressions  Backward jumps  Reading rate  Duration of fixation  How long does each one take?  Span of recognition  How much are they seeing with each fixation?  ie..50 means they see half of a word per fixation  Directional attack  Fixations/Regressions  Efficiency  Grade equivalent Visagraph/Readalyzer  Prescribing Based Off the Binocular Vision Examination Part 2 MARC B. TAUB, OD, MS, FAAO, FCOVD CHIEF, VISION THERAPY AND REHABILITATION SOUTHERN COLLEGE OF OPTOMETRY EDITOR IN CHIEF, OPTOMETRY & VISUAL PERFORMANCE  Nearpoint Stress Model How does this work? Stress causes vergence to localize closer than accommodation As per the AC/A ratio, when vergence is stimulated, so will accommodation When accommodation is stimulated, vergence will stimulate more, ramping up even further.  Nearpoint Stress Model  How do we naturally stop the stress process?  What is a buffer?  Some examples Chemistry Banking Vision  Hyperopia and exophoria are the visual system’s buffers.  Adaptation to Visual Stress  Signs  Exophoria (>6X’) or Esophoria (45  Too much plus is a bad thing!  9 year old female  Complains of blur at distance with glasses  Patient reports better vision without glasses  Grades are good except reading below grade level  COVD checklist 49  Avoids near work/reading  Trouble keeping attention on reading  Words run together with reading  Holds reading too close  Reading comprehension down  Too much plus is a bad thing!  VA with correction (no clue what though)  20/20 @ dist and near  Stereo  20 sec  Cover test  Ortho @ dist, 4 Exo @near  NPC  To the nose x 3  Too much plus is a bad thing!  Retinoscopy Final Rx  +2.00-0.75 x 090 OU – +1.50 20/20 D & N Follow up in one month  MEM for Rx check  +1.50 – Run DEM or King  Trial frame Rx Devick  +1.50 20/20 D & N  MEM through TF  +0.75 OU  Too much plus is a bad thing!  Six weeks later…  Still complains of blur with glasses  VA with and without glasses  20/20 D @ N  Corrected VA improved after looking at chart for several seconds  New trial frame performed  +1.00 OU  Patient reported better clarity at distance  Too much plus is a bad thing!  Proof is in the pudding!  DEM without Rx  Vertical 40 sec  Horizontal 106 sec  DEM with Rx  Vertical 48 sec  Horizontal 49 sec  The case of the blinking girl  8 year old female  Excessive blinking the past two months  Doing well in school  No trouble with reading or copying from the board  Started medication for ADHD four months prior  COVD checklist 4  VA  20/20 @Dist  20/15 @ Near  The case of the blinking girl  Stereo-25 sec  Cover test  Ortho @Dist  6 exo @ Near  EOM  Head movement in right and left gazes  Heavy blinking when crossing midline  NPC-Break at 40 cm x 3  Accommodative amplitudes-6D OU  The case of the blinking girl  Retinoscopy (Distance) Vergence ranges (with  -0.50 OD, -0.25 OS rx)  MEM – BI @ Dist x/14/2  +1.00 OU – BO @Dist x/18/4  Trial frame – BI @ Near x/24/8  +0.75 – BO @Near x/30/8  The case of the blinking girl  Phoria in phoropter  Ortho @ Dist  4 exo @Near  NPC with Rx  8cm break/18 cm recovery  King-Devick with Rx  Part I-20.4 sec  Part II-23.7 sec  Part III-37 sec  Treatment  Full time +0.75, return in 5-6 weeks for check  The case of the blinking girl  Two month follow up NPC:TTN X 3  VA COVD checklist: 5  20/20 OD, OS, OU @ Dist Vergence ranges  20/15 OD, OS, OU @ Near – BI @ Near x/16/12  Stereo: 20 sec – BO @Near x/20/12  CT: Ortho/ 4 exo  Sudden Vision Decrease  A 9 year old female complains of missed letters on the eye chart at medical exam in both eyes for 1 year.  She has a hard time reading the board at school. She does not like reading and her favorite subject is math.  She started out on honor roll at beginning of year and the grandmother reports grades started to slip towards the end of the year.  Denies headaches when reading. Sudden Vision Decrease Uncorrected VA Distance 20/80 OD, 20/125 OS, 20/100 OU Near 20/80 OD, 20/150 OS, 20/60 OU No improvement on pinhole Pupils PERRLA Confrontation Fields Constricted 360 EOMs Full OU Stereo Butterfly Pt could only see the top of the wings of the butterfly (2,000 sec arc) Hirschberg Aligned OU Near Point of Convergence To the nose X 3 Retinoscopy-distance +0.50-0.50 X 090 OU Retinoscopy-near Through plano +1.00 OU Wet Retinoscopy (Tropicamide +0.50 OU, 20/40 OU 1%) Internal/External Health No abnormalities noted on anterior or posterior segment evaluation Humphrey Visual Field Severe constriction with minimal fixation losses OU (See figures on next slide) Sudden Vision Decrease  Sudden Vision Decrease  A tentative diagnosis on non-malingering syndrome (Streff syndrome) was made.  A final prescription of +0.50 OU was given for full time wear.  The patient and grandmother were educated.  One thing of note was that while the grandmother denied family/home life issues, she would not leave Kiesha alone throughout the examination.  Follow-up testing for a VEP and repeat VF was scheduled in one month following full time wear of +0.50 OU.  Streff Syndrome  The VEP was performed two weeks later.  Testing was performed on the Diopsys using pattern reversal checkerboards at the following sizes 8 X 8, 16 X 16, 32 X 32, 64 X 64.  The P100 values were within expected timing.  Amplitudes showed significant binocular summation with monocular equality.  No neurological problems were present  consistent with the diagnosis of non-malingering syndrome.  Sudden Vision Decrease Four week follow up Corrected VA Distance 20/20 OD, OS, OU The patient reports not Near 20/20 OD, 20/15 OS, 20/20 OU liking to wear glasses, but wears them around Pupils PERRLA 4 hours per day. Confrontation Fields Grossly full in all quadrants She reports that glasses help but there EOMs Full OU is slight distance blur. Stereopsis (Randot) 30 arc sec During the history Near Point of Convergence To the nose X 3 Keisha revealed that boys had Retinoscopy-near Through +0.50: +0.50 OU recently been bullying her at school. Sudden Vision Decrease  The Humphrey visual field showed significant improvement OU. OD showed no defects but fixation was poor OS showed no defects and fixation was excellent The patient was to continue use of the +0.50 OU for full time wear and follow-up in six weeks for a repeat visual field. Unfortunately, the patient was lost to follow up.  To Rx or not to Rx, that is the question!  4 year old-failed school vision Retinoscopy: screening – +2.25-1.00 X 015  VA: 20/30 OD, OS, OU at – +2.25-1.00 X 160 distance and near Retinoscopy:  Stereo: 30 sec – +1.50-1.00 X 015  NPC: 2/4 X 3 – +1.25-1.00 X 160  Amps: 12 OD, OS – 20/30, OD, OS, OU Cyclo Ret: – +3.00-1.50 X 010 – +2.75-1.50 X 160 Prescribe for developmental age: Hyperopia and Astigmatism  To Rx or not to Rx, that is the question!  5 year old-failed school vision screening  VA: 20/50 OD, OS, OU at distance and near  Stereo: not understood  NPC: not understood  Amps: not understood  Retinoscopy: +1.50-1.50 X 180, +1.50-1.00 X 180  Final Rx: +1.00-1.50 X 180, +1.00-1.00 X 180  VA with any rx combo  20/20, OD, OS, OU @ D and N  What would you do? Prescribe for developmental age: Hyperopia and Astigmatism  What to Rx, that is the question!  7 year old Retinoscopy: – +1.50-4.00 X 180  VA: 20/60 OD, OS, – +1.50-5.00 X 160 OU at distance and 20/40, OD, OS, OU near Trial frame:  Stereo: 200 sec – +1.00-2.00 X 180  Cover test: ortho at – +1.00-2.50 X 160 distance, 4 XP at near 20/40, OD, OS, OU Cyclo Ret: – +2.00-4.00 X 180 – +2.00-5.00 X 180  What to Rx, that is the question!  18 month old Retinoscopy:  VA: 20/150 OD, OS, OU – -3.50-1.50 X 180 at distance and near – -3.50-1.50 X 160  Cover test: ortho at 20/100, OU distance, 4 XP at near Cyclo Ret: – -3.00-1.50 X 180 – -3.00-1.50 X 180 Prescribe for developmental age: Myopia  What about the dreaded IXT?  Pediatric Eye Disease Goal---reduce the Investigator Group frequency and size of the  183 children ages three to turn to enhance fusion 10 for three years---only success rates 15% deteriorated – surgery(with functional  defined as having a constant results included)-43% exotropia ≥10 prism diopters (PD) at distance and near or a – occlusion-37% decreased stereopsis of ≥20.6 log – over-minus-28% arcsec (tested with Randot Preschool Near Stereoacuity) – prism therapy-28%  exotropia control, stereopsis and – and vision therapy-59% magnitude of the exodeviation at distance improved  A Case Series of IXT  3-year-old male  Follow-up after having been prescribed over-minus at his last visit several months prior.  At both visits (previously without, and at this visit with, spectacles), he showed a 40 PD intermittent alternating exotropia at distance (80% of the time, OD>OS) and orthophoria at near.  Refused to wear the glasses, and when he did wear them, he looked over them.  VA with the glasses-20/30 OU, without-20/20 OU  Keystone Basic Binocular (KBB) test at near.-gross stereopsis  A Case Series of IXT  We attempted prism to see if there were any changes and observed none.  Modified home vision therapy program of basic bilateral eye movements.  Eye stretches, ball playing and balloon hitting A Case Series of IXT  A Case Series of IXT  3-year-old female Over-minus of -1.50 DS on top of  Second opinion after the astigmatism correction surgery was recommended – Acuities dropped to 20/80 OU  Uncorrected acuities-- 20/25 OD, 20/30 OS and 3 PD base-in in each eye 20/25 OU – modicum of success  Cover test showed an 18 – cover test now showed 10 PD intermittent right exophoria at distance and exotropia 50% of the time at distance and 4 orthophoria at near. exophoria at near. We prescribed the astigmatism  Stereopsis was positive along with the prism for full-time using the KBB, as the child wear and requested basic eye localized several pictures. stretches. She will be reevaluated  Retinoscopy in two to three months.  plano -1.00x180 OU  A Case Series of IXT  15-year-old male presented for his yearly exam.  Wearing -6.00 DS OU, his acuities were 20/80 OU  Cover test showed 25 intermittent alternating exotropia at distance and near  Global stereopsis was absent  Post refraction  -7.50D OU (20/20 OU)  20 intermittent alternating exotropia at distance and 15 exophoria at near  3 PD base-in in each eye, the cover test showed 10 exophoria at distance and near.  KBB was retested, and a positive response was recorded  He will be reevaluated in two to three months  Thank you! [email protected]