VISUAL FIELD - Perimetry

Samay shah
Trupti parmar

1. PERIMETRY -Samay Shah -Trupti Parmar 3 nd year B.OPTOM BMCO , Surat

2. Presentation Layout Introduction of Visual Field Hill of vision Method of studying visual fields History of perimetry Indications of perimetry Terminologies How to perform perimetry test Perimetry interpretation Advance techniques for visual field measurement

3. Introduction of perimetry Perimetry – A standard test in ophthalmology and optometry to assess a patient’s visual field. The devices used to perform this evaluation are called perimeters. Perimetry is performed for several reasons; 1)detection of pathologies 2) evaluation of disease status 3) follow-up of pathologies over time to determine progression or disease stability 4) determination of efficacy of treatment 5) visual ability testing.

4. Perimetry is most commonly used to diagnose glaucoma, but it is also often used to assess visual loss resulting from retinal diseases, as well as optic nerve, chiasmal or post-chiasmal damage due to trauma, stroke, compression and tumors. Perimetry is used regularly for visual ability testing. Its most common use is to test a person’s visual ability to drive.

5. Introduction of visual field The visual field of a person is defined as the area in which a person can see at a given moment relative to the direction of fixation, without head or eye movement. The entire expanse of space visible at a given instant without moving the eyes. The monocular visual field consist of …. superiorly : 50 deg , nasally : 60 deg , inferiorly : 70 deg & temporally : 90 deg

6. THE HILL OF VISION – A VISULZATION OF VISUAL FUNCTON Its a 3D representation of the retinal light sensitivity. Traquair reflects the visual field in the light-adapted or photoptic visual field. The highest concentration of cones is in the fovea , most of these cones project to their own ganglion cell. The contour of the island of vision changes greatly in the mesopic(twlight)

7. Con… and scotoptic (dark-adapted) states . In the dark-adapted island of vision , the contour is flatter than in the light-adapted state .

8. Methods of measuring the visual field The visual field can be tested in a few different ways , including the confrontation visual field exams , tangent screen test & perimetry exam . Your Dr. may perform one or a combination of these testes to examine your visual field . Using the result of these tests , your Dr will be able to determine if you are having trouble seeing in certain areas of your visual field , as well as possible causes for these difficulties .

9. 1. Tangent Screen Exam Also known as begrrum’s screen or campimetry The tangent screen exam (Goldmann field exam ) can be conducted in your eye doctor’s office . Patient will be seated about 3 feet away from a screen . This screen will have a target in the center for you to focus on throughout the test .

10. Con…. The computer will generate image on different areas of the screen .Without moving your eyes , you will tell your Dr. when you’re able to see objects in your side vision . Your Dr. will be able to use the information collected to from a map of your visual field . This will help them determine if there are certain areas in your visual field that you are not able to see . The location of these areas can help your Dr. diagnose the cause of the visual field problems .

11. 2. Perimetry Perimetry is the systemic measurement of visual field function . Perimetry will detect loss of peripheral vision & provide a map of that loss which will be helpful in diagnosing the cause of the loss . It is the measurement of HILL OF VISION in terms of establishing the patient’s differential light sensitivity across the visual field.

12. When is perimetry called for? Perimetry is essential in glaucoma management . It also is frequently useful in diagnosing & managing neurological diseases and it has a role in the diagnosing & managing of some retinal diseases .

13. HISTORY 1970 – The original octopus perimeter was first introduced . Bucz , of its room size & high expensive nature it become unpopular . 1980-, BJERRUM developed tangent screen 1982 – Humphrey field analyzer was first displayed at American Academy of Ophthalmology . 1983 – Michal Patella showed its first clinical trail . 1984 – started production & become very popular bucz , of its small size & affordable price .

14. Indications of Perimetry Detection of glaucoma , progression Chorioretinal lesions Optic disc & optic nerve lesions Neuro-ophthelmological diseases Abnormal color vision Reduction in visual acuity that can’t be improved with a pinhole , stenopaic slit or refractive correction

15. Types of Perimetry According to the principal : 1. Kinetic 2. Static Clinically 1. Automated static perimetry 2. Manual kinetic & static perimetry using a (Goldmann type bowl perimeter ) 3. Potable perimetry

16. Kinetic perimetry Outer visual field is determined by moving objects from the non-seeing area to the center . Uses a moving object of a fixed size & intensity . It is manual Advantages : Allows large areas to be traversed in a fairly short period. Less expensive & durable . Perimetrist is constantly communing with the patient so it is more comfortable . Disadvantage : Reproducibility & reliability is not constant in the manual kinetic perimetry . Early changes can overlooked Eg : Goldmann perimeter

17. WHAT IT IS BEST AT DETECTING:- Small changes in spatial extent of a defect Peripheral changes Remaining vision in advanced diseases USES:- Neuro-ophthalmological conditions {vision loss or disturbance ,double vision unequal pupils etc…} Peripheral retina diseases Low vision Patient with cognitive impairment

18. Static perimetry The outer boundary of island of vision determined by measuring the retinal sensitivity at each point . The test location is fixed while the intensity of the test object of known size is varied. It’s automated Advantage: Reliability and reproducibility Clinical gold standard High precision sensitivity thresholds Fully automated Disadvantage: Manual static perimetry is tedious Eg : Octopus or the Humphrey Field Analyzer

19. WHAT IT IS BEST AT DETECTING:- Small changes in sensitivity thresholds Changes in the central area USES:- Glaucoma Macular diseases Visual ability testing

20. Manual perimetry

21. Portable perimetry palsamScan VF2000 is potable , battery operated , virtual based visual field analyzer developed to be able to measure the pt’s visual field defect accurately and reliably . The VF2000 is composed of 3 major sections that are connected to each other wirelessly & there are no wires to deal with when using this system . The 3 major components are: 1. The test goggles that are worn by the patients 2. The controller device that is used by the health care provider to set the parameters and to monitor the progression of the test 3 . The clicker that the patient will use to notify the system that a stimulus has been detected .

22. Why portable is best ? No Need For Dedicated dark room No need to patch the fellow eye No need for trial lenses on majority of patients Measure any patient anywhere Proven accuracy Increased your office revenue Disposable and protective facemasks Can be used for pediatric patients Disadvantage : Don’t provide enough clinical data to manage glaucoma patient

23. Few Terminologies Threshold : -Differential light sensitivity at which a stimulus of a given size and duration of presentation is seen 50% -The threshold is the physiological capacity to detect a stimulus at a given location under specific condition. Suprathreshold : - 95% of the projected times -stimulus- made suprathreshold – increasing size or duration Infrathreshold : -Low intensity stimulus – 5% Isopter : a line on a visual field representation – connecting points the same threshold .

24. -Depression: a decrease in retinal sensitivity - Scotoma : an area of decrease retinal sensitivity within the visual field surrounded by an area of greater sensitivity . Decibel (dB): -Its value depends on the max. illumination of the perimeter 40 dB = 1 asb unit 0 dB = 10,000 asb unit -The conversion from asb to dB is log & not a simple multiplication factor . -Good retinal sensitivity = 40 dB -Poor retinal sensitivity = 0dB -Dimmest light = 1 asb -Brightest light = 10,000 asb

25. 30-2 central threshold test pattern no. of test points: 76 Dist. b/t each two points : 6 deg Indications : suspect cases of glaucoma

26. 24-2 central threshold test pattern No. of test points : 54 Dist. b/t each two points : 6 deg Indications : establish cases of glaucoma

27. 10-2 Central threshold test pattern No. of test points : 68 Point density : 2 deg Indication : advance case of glaucoma

28. Macular program No. of test pints : 16 Point density : 2 deg Indications : advance case of glaucoma

29. How to perform perimetry test Perimetry should be performed in a Distraction-free environment , to enable the patient to concentrate on the perimetric test . The room should be quiet, with no activity distracting the patient, and should be at a comfortable room temperature. The room should be kept clean and free of dust and particles. The perimeter is automatically calibrated each time it is turned on.

30. A perimeter should be set up in a distraction-free, dimly-lit environment.

31. STEP-BY-STEP PATIENT INSTRUCTIONS 1 Perimetry tests your central and peripheral vision. 2 Be relatively still once positioned. 3 Always look straight ahead at the fixation target. Do not look around the bowl for stimuli. 4 Press the response button whenever you see the stimulus. a. The stimulus is a flash of light. b. Only one stimulus is presented at a time. c. The stimulus might appear anywhere. d. Some stimuli are very bright, some are very dim, and sometimes no stimulus is presented. e. You are not expected to see all stimuli. f. Do not worry about making mistakes.

32. Con….. 5. Blink regularly to avoid discomfort. a. Don’t worry about missing a point, the device does not measure while you blink. 6. If you feel uncomfortable or are getting tired a. Close your eye for a moment, the test will automatically stop. b. The test will resume once you open your eye. 7. If you have a question a. Keep the response button pressed; this will pause the test.

33. CORRECT PATIENT POSITION The patient should be seated in a comfortable position that can be easily maintained throughout the test. A height-adjustable chair with a backrest and, if available, armrests should therefore be used.

34. CORRECT EYE PATCH POSITION: Before fully positioning the patient, the eye not being tested should be covered with an eye patch that allows the patient to blink freely. +++++++++++++++++++++++++++++++++++++++++++++++

35. PLACING AN ADEQUATE TRIAL LENS The trial lens calculator is helpful in determining the adequate spherical and cylindrical trial lenses, based on the patient’s current refraction and age. Trial lenses with a narrow metal rim should be used, to prevent the rim of the trial lens from blocking the patient’s field of view. We use full aperture trial lenses.

36. CORRECT EYE POSITION Once the patient is correctly positioned in the device, it is important to ensure that the eye is also correctly positioned. The left-hand panel shows an eye in the video monitor that is correctly positioned ,with the cross-hair target located within the boundaries of the pupil. The right-hand panel shows an eye that is incorrectly positioned , with the cross-hair target located outside the boundaries of the pupil.

37. SELECTING A TEST PATTERN INDICATION RECOMMENDATION COMMON ALTERNATIVES GLAUCOMA/CENTRAL FIELD G (Glaucoma) 32, 30-2, 24-2 MACULA M (Macula) 10-2 FULL FIELD (NEURO, RETINA) 07 Kinetic FOVEA F (Fovea) BLIND SPOT B (Blind spot) Kinetic LOW VISION M, G, 07 depending on pathology Kinetic SCREENING FOR ABNORMAL VISION Screening 28 DRIVING ET (Esterman) FG ( Führerscheingutachten ), Kinetic BLEPHAROPTOSIS BT (Blepharoptosis) Kinetic BLINDNESS BLINDNESS

38. 1 .) TEST PATTERNS FOR GLAUCOM A:- Glaucoma is a disease resulting in the degeneration of retinal nerve fiber bundles in the eye. Typical defect patterns follow the distribution of the retinal nerve fiber bundles and there is a clear separation along the superior and inferior hemifields at the horizontal meridian. Since glaucomatous visual field defects typically occur within the central visual field, the best trade-off between test duration and accuracy is achieved by using a central 30° test pattern. In very advanced glaucoma, the visual field and therefore, it is common to switch to a 10° macular test pattern in advanced glaucoma .

39. . 32/30-2 AND 24-2 PATTERNS The 32, 30-2 and 24-2 patterns are similar to the G pattern in that they cover the central visual field and respect the vertical and horizontal meridians. In contrast however, they are not optimized for specific pathologies. Instead, all test locations are equidistant from each other and separated by 6°.

40. 2.)TEST PATTERNS FOR NEUROLOGICAL VISUAL FIELD LOSS Neurological conditions lead to a large variety of typical visual field defect patterns which are very specific, depending on the location at which the visual pathways are affected Lesions of the optic disc and optic nerve lead to unilateral (i.e., only affecting one eye) visual field defects. Common optic nerve and nerve head diseases include disc edema, optic neuropathies, optic neuritis, compressive lesions such as those caused by idiopathic intracranial hypertension, and a number of congenital abnormalities, such as optic nerve head drusen. Chiasmal lesions resulting from diseases such as pituitary adenomas and related lesions typically result in bitemporal (i.e., left and right eye defects are mirrored) hemianopias, which progress from the superior to the inferior hemifield, but always respect the vertical midline.

41. 3)TEST PATTERNS FOR THE MACULA: M PATTERN The M pattern is most commonly used for the testing of drug-induced maculopathies, to follow up advanced-stage glaucoma patients, and for visual function testing in patients with AMD or other macular dysfunction.

42. 4)TEST PATTERNS FOR VISUAL ABILITY TO DRIVE:- Safe driving requires a large horizontal field of view , to be able to notice other cars coming from the side, and a fairly intact central field of view, to be able to notice obstacles ahead. As driving is performed with both eyes open, the binocular field of view is relevant for safe driving.

43. BT PATTERN FOR BLEPHAROPTOSIS(BT test):- The BT pattern is designed speciically for blepharoptosis testing and covers the area of the lid lines in the superior Some legislations also accept driving ability tests performed with kinetic perimetry. As there is no vision underneath the lid line, qualitative testing (seen, not seen) is sufficient. The BT pattern for blepharoptosis testing covers the area of the potential lid line.

44. Interpretation of perimetry

45. Zones of field analysis 1. Independent of normative data:- zone 1 : Patients data/ test data zone 2: Reliability indices/ foveal threshold zone 3: Raw data zone 4: Gray scale 2. Dependant of normative data:- Zone 5 : Total deviation numerical plot zone 6 : Total deviation probability plot zone 7 : Pattern deviation numerical plot Zone 8 : Pattern deviation probability plot Zone 9 : Global indices Zone 10 : Glaucoma hemifield test Gaze tracker(Eye tracking)

46. Zone1: Patients data/ test data Fixation monitor : Blind spot Color of stimulus : White Background illumination : 31.5 asb 1.Age of the patient: it is very important to enter the age of patient accuracy. 2. Size of the pupil : Normally the size of the pupil should be b/t 3-4 mm 3. Refractive error : The pt’s near vision refractive error must be properly corrected. otherwise the visual field will show generalized depresstion. 4.Stimulus size The standard size of the stimulus is size III for all routine tests & size V for advance glaucoma CONSTANT

47. Zone 2 : Reliability indices/ foveal threshold Reliability indices fixation loss : >20% is unreliable false positive : >33% is unreliable false negative : > 33% is unreliable

48. Zone 3: Raw data Exact retinal sensitivity in dB units of the selected points Only numerical value of the retinal sensitivity is displayed in the raw data & dB units are omitted. in the raw data , ‘0’ indicates Absolute Scotoma(no response to the highest light sensitivity i.e. 10000 asb unit ) ‘40’ indicates highest retinal sensitivity i.e. 1 asb unit

49. Zone 4: Gray scale Based on actual threshold value at each locating Areas of high sensitivity are denoted by lighter shades & areas of low sensitivity are denoted by darker shades. Quickly identification overall depression Not use for diagnose Good for pt’s education

50. Zone 5 : Total deviation numerical plot Words O indicates retinal sensitivity is equal to mean value of same age group Value without sign (positive) the measured retinal sensitivity is better than mean normal values of the same age group Numerical value with negative sign indicates the measured retinal sensitivity is worse than the mean normal values of the same age group

51. Normal retinal sensitivity Patient's retinal sensitivity Difference

52. zone 6 : Total deviation probability plot Aim to be field chart is show that the field loss in scotomatous form Probability value (P value ) : Indicates the significance of the defects lower the p value the grater is its clinical significance Clinical significance : if there are abnormal points in total deviation plot that persist in pattern TDNP TDPP P value

53. Zone 7: pattern deviation numerical plot It is a modified from of TDNP to bring out scotomas 7 th best retinal sensitivity of TDNP is converted to zero Addition of the threshold value that converts the 7 th best retinal sensitivity of TDNP to all points in TDNP The pattern deviation numerical plot is also the basis for glaucoma hemifield test analysis The TDNP is converted to PDNP without changing the contour of hill of vision

54. TDNP PDNP

55. Zone 8 : pattern deviation probability plot It is similar to formation of TDPP from TDNP It bring out deep scotomas in a generalized depression The main deference b/t TDPP & PDPP is that it differentiate b/t actual field defects and loss of sensitivity due to media opacities such as cataract, corneal haze etc….

56. PDNP PDPP

57. ZONE 9: Global indices These are develop to express the height of hill of vison and contour of hill of vision It include : 1. mean deviation (MD) 2 . Short term fluctuation (SF) 3. Corrected pattern standard deviation (CPSD) 4. Pattern standard deviation (PSD)

58. 1 . MEAN DEVITION: Indicates overall depression or elevation Positive indicates better than normal field and vice-versa Negative value indicates that the pt’s overall sensitivity is worse than the average normal Expressed in dB units with p value

59. 2. Short term fluctuation -It measures the variation at each point on repeated thresholding in the same test -Value is almost always less than 3 dB -Use to correct PSD to produce CPSD -Indicates reliability and pathology 3. Corrected pattern standard deviation (CPSD) - Intra testing variability (SF) is removed from PSD for produce CPSD -CPSD is not calculated if SF is not estimated during the test

60. 4 Pattern standard deviation :- -Derived from total deviation plot -Tells us how different each point is from one and other - Actual irregularity in the field

61. Zone:10 Glaucoma hemifield test 5 sectors in the upper field are compared to 5 mirror images in the lower Five sectors are: 1 . OUTSIDE NORMAL LIMITE If, difference found in 1% population 2 . BORDERLINE If difference found in up to 3% population 3 . ABNORMALLY LOW SENSITIVE Best sensitive part is seen in less than 5% of the population 4 . ABNORMALLY HIGH SENSITIVE Best sensitive part seen is more than that found in 99 – 5% population

62. Gaze tracker : Heiji-Kraku method of fixation monitoring – it provides index of quality of patient fixation during examination by periodically exposing stimuli in blind spot Infra red gaze monitors Upward spikes indicates that the patient has lost fixation Short reaching the top line indicate 5 degree off fixation Long spikes indicate pt blink at the time of fixation check

63. Advance techniques for examine visual field SWAP [Short Wave Automated Perimetry] FDP[Frequency Doubling Perimetry] HPRP[High Pass Resolution Perimetry] Flicker Perimetry Multifocal Electroretinaography ACCUMP[Multifocal Visual Evoked Potential] Motion Perimetry

64. Some different reports Early peracenral Scotoma

65. Moderate inferior acute Scotoma

66. Moderate superior acute scotoma

67. Ptosis

68. Cataract

69. ? ANY DOUTS ?

70. VISUAL FIELDS EXAMINATION AND INTERPRETATION – THOMAS J. WALSH A visual field evaluation with automated devices by GR Readdy Ophthalmology - Yanoff and Duker REFFERANCES

71.  Thank you 