Visual System and Colour Vision Part 1 PDF

Visual System and Colour Vision Claudia Stern Overview Introduction Anatomy of the eye Refraction Visual acuity assessment Visual aids Ophthalmological examination techniques Ocular muscle balance  Overview Colour vision Methods of testing: pseudoisochromatic plates, lantern tests,...

Visual System and Colour Vision Claudia Stern Overview Introduction Anatomy of the eye Refraction Visual acuity assessment Visual aids Ophthalmological examination techniques Ocular muscle balance  Overview Colour vision Methods of testing: pseudoisochromatic plates, lantern tests, anomaloscopy Visual fields — acceptable limits for certification Assessment after eye surgery Monocularity and medical flight tests Importance of standardization of tests and of test protocols Ophthalmological examination intervals Ophthalmological requirements Relation to aviation duties At the end of these courses you should: Theoretically know how to examine the eyes as an Aeromedical Examiner Know how to test visual acuity Know at which timepoint an ophthalmological examination is necessary Understand the ophthalmological report Understand the meaning of the regulations Be able to apply the correct limitation for corrections and colour vision deficiencies Be able to decide on fitness or denial Transfer the information to LAPL and Cabin Crew on your own Eye Anatomy  Emmetropia – Normal eye C. Stern Hyperopia – sign plus (+) The eye is too short and the focus lays behind the retina Correction with converging lens Myopia – sign minus (-) The eye is too long and the focus lays in front of the retina Correction with diverging lens  Astigmatism C. Stern Presbyopia Accommodometer Testing the Accommodation Accommodation change throughout the years Accommodation determined by nearpoint age diopters near point 16 12 8 18 12 9 20 11 9 22 11 9 24 10 10 26 10 10 28 9 11 30 9 11 32 8 12 34 8 13 36 7 14 38 7 15 40 6 17 42 5 20 44 4 22 46 3 30 48 3 40 50 2 57 52 2 63 54 1 71 56 1 76 60 1 83 Convergence Spectacle Prescription – multifocal/progressive glasses Hyperopia Astigmatism Axis Near addition for presbyopia Objective Refraction in Miosis Subjective Refraction  Contact lenses C. Stern Contact lenses The values for contact lenses are usually -0,25 to -0,5 Dioptres below the values for spectacles Astigmatism are not corrected in contact lenses up to 1 diopters Astigmatism of more than 1 dioptres can be corrected by toric lenses Single focus contact lenses including toric lenses are allowed to be used What do you need for the examination as an AME? Distant visual acuity charts Near Visual acuity charts Vision tester Documentation EMPIC Empic Check the identity First: Examination of the right eye  Landoltring DIN 58220 and ISO 8596 The ring has a stroke width and a gap measuring 1/5 of the outer diameter and is shown in different directions, usually the in eight different directions. Logarithmic graduation Landoltring Start: Two rows below the expected visual acuity In order to rate this level as seen, the applicant should be able to correctly identify at least 60% of the optotypes The applicant must correctly identify 3 out of 5 or 6 out of 10 rings Inappropriate Covering Appropriate Covering  Necessary Eye Examinations at the Revalidation or Renewal Examination for Class 2 History Distant- , intermediate- und near visual acuity uncorrected and with best optimal correction, if needed Examination of the external eye, anatomy, media and fundoscopy  Necessary Eye Examinations at the Revalidation or Renewal Examination for Class 2 History Distant- , intermediate- und near visual acuity uncorrected and with best optimal correction, if needed Examination of the external eye, anatomy, media and fundoscopy  Testing Distance 5 or 6 meters Distant Visual Acuity Monocular Distant Visual Acuity Binocular Requirements Visual Acuity Class 2 Distance monocular: > 0,5 Distance binocular > 0,7 Intermediate Visual Acuity Reading Charts– Correct Distance 30 – 50 cm Reading Charts Near and intermediate Visual Acuity Testing Monocular and Binocular Monocular Testing Binocular Testing N Charts N for near Font: Times New Roman The size of the letters is based on the old printer system in which one point is 0,35 mm Thus 5 point type is one in which each letter is cast on a block 1,75 mm tall Reading distance 40 cm N chart testing N Chart Testing Reading Charts – Test Distance differs per chart Vision Tester Block Sehprüfgerät TOPAS Bon Optic Führerschein-Sehtestgerät FT2 Essilor Visiotest Physiologique FIM VISIOLITE Master Oculus Binotest/Binoptometer II Oculus Sehtestgerät Binoptometer 4P Oculus Sehzeichenprüfgerät EasyVis XL Oculus Sehzeichenprüfgerät NIDEK SC-1600P Titmus Sehprüfgerät Titmus 2a, Titmus 2s Topcon Sehprüfgerät SS - 3 Vistec Sehtestgerät Optovist Vistec Sehtestgeräte R20, R21, R22 Vistec Sehtestgeräte Rodatest 300 und 302 Requirements Visual Acuity Class 2 Binocular near (30-50 cm) > N5 (0,7) Binocular Intermediate (100 cm) > N14 (0,5/0,63/0,7) ICAO: 0,5 Numerical: 0,63 Differences among the countries: ask the National Civil Aviation Authority Forced head position can be used to reduce diplopia in eye muscle palsy Straight look into the vision tester Applicant should use the glasses that they wear Only one correction for all distances It is not allowed to change the glasses or take them off  Necessary Eye Examinations at the Revalidation or Renewal Examination for Class 2 History Distant- , intermediate- und near visual acuity uncorrected and with best optimal correction, if needed Examination of the external eye, anatomy, media and fundoscopy  Examination of the outer and the anterior part of the eye direct Ophthalmoscope Big, round light for the outer eye Slit: anterior part of the eye Direct Ophthalmoscope Refraction of examiner and applicant Math: Applicant -3,0 dpt AME -2.0 dpt = -5,0 dpt Applicant +5,0 dpt AME -2.0 dpt = +3.0 dpt C. Stern C. Stern C. Stern C. Stern Position of the Eyes Distance between the eyes Position within the orbita Parallel? Lids? Phoria Phoria means the position of both eyes or eye axes in relation to each other In orthophoria both eye axes are so situated that there is a muscle balance between them also if you disconnect the binocular vision/fusion and both eyes will still fixate the same object and not move Heterophoria is a latent tropia but normal if the values are not too high Cover Stereo vision Highest developed function of binocular vision Correct recognition and location of objects in space Judgement of distances Stereotests – if there is stereo vision there is also binocular vision  Funduscopy direct Ophthalmoscopy Upright image in 16 times magnification Physician and pilot sit opposite to each other Refractive error of the pilot and the physician must be considered Papilla (colour, circumscription, excavation) Macula Vessels Direct Ophthalmoscope direct Ophthalmoscopy Papilla Pale pink Sharp margine Longitudinal oval Excavation is lighter as the normal colour of the papilla (cup/disc ratio) Vessels are wider the closer they are to the papilla Necessary Examinations Class 2 Routine eye examination Ophthalmological examination necessary if there is: Any decrease in best corrected visual acuity or substantial decrease in the uncorrected visual acuity Occurrence of eye disease, eye injury, or eye surgery  -Änderung der Brillen-/Kontaktlinsenstärke Spectacle/contact lens prescription change since last examination Comprehensive Eye Examination history; visual acuities - near, intermediate and distant vision (uncorrected and with best optical correction if needed); examination of the external eye, anatomy, media and fundoscopy; ocular motility; binocular vision; colour vision and visual fields; further examination (including tonometry) on clinical indication Assessment of mesopic contrast sensitivity  VDL: Correction for defective distant vision (Vision Distance Limitation) Wear corrective lenses and carry a spare set of spectacles VDL: Correction for defective distant vision VDL: Correction for defective distant vision Contact lenses may not be worn until declared so by the AME or AeMC If contact lenses are worn a spare set of spectacles should be carried VNL: Correction for defective near vision a pair of spectacles for near use shall be kept Look overs readily available (Vision Near Limitation) a spare set of similarly correcting spectacles shall be readily available for immediate use VML: Correction for defective distant, near and intermediate vision Wear spectacles that correct for defective distant, intermediate and near vision and carry a spare set of spectacles Correction for defective distant, intermediate and near vision: whilst exercising the privileges of the licence, the holder of the medical certificate should wear spectacles that correct for defective distant, intermediate and near vision as examined and approved by the AeMC, AME or GMP. Contact lenses or full frame spectacles, when either correct for near vision only, may not be worn. A spare set of spectacles, approved by the AeMC, AME or GMP, should be readily available Which limitation? Refraction: R: -1,5 sph L: -1,75 sph Which limitation? Which limitation? Which limitation?  Which limitation? VNL for near and intermediate Glasses: +2,0 sph both eyes  Which limitation? VML because near vision drops with glasses in myopia C. Stern  Visual acuity – Limitation? Eye specialis t VML Limitations Limitations for glasses can be imposed by the AME, but can not be taken out out or changed by the AME (VDL into VML) AMC1 MED.B.001 Limitations to medical certificates (d) (2) For class 2 medical certificates, limitations may be removed by the medical assessor of the licensing authority or by an AeMC or AME in consultation with the medical assessor of the licensing authority. Colour Deficiency 8% of males Most commonly involves red and/or green Is sex-linked recessive Is inherited from the mother Requirements Class 2 Ishihara-plates (24 plate version): the first 15 plates must be correctly identified If fail: should be colour safe (further colour vision testing) If not: Daytime only (VCL) Colour vision must not be tested at renewal examination  Colour Vision  0 errors  Anomaloscopy/lantern test/CAD  Nothern Daylight 6500 Kelvin Ishihara-Testing 24 plate version distance of 75 cm rectangle to the eyes of the applicant random order the examiner turns the pages each eye separately without hesitation (< 3 seconds per plate) northern daylight > 0 errors - further examinations are necessary Colour Vision Tests Ishihara-Test: Google: 10.200.000 results Limitation VCL Valid by day only Allows private pilots with colour deficiency to exercise the privileges of their license by daytime only. Only class 2. Anomaloscopy Normal Anomal Quotient: 0,7 – 1,4 Trichromat with 4 matching scale units Color Assessment and Diagnosis Test (CAD) You are the AME Initial class 2 applicant: Ishihara plates: R: 1 error L: 0 error What do you do? Limitation VCL Anomaloscopy or Lantern or CAD Test Reduced vision requirements Class 2 Reduced vision in one eye: Better eye distant visual acuity > 1,0 uncorrected or corrected Binocular visual field normal Meets the standards for near and intermediate visual acuity No significant pathology Satisfactory medical flight test No Refractive error limit Amblyopia Lack of development of central vision in one eye that is unrelated to any eye health problem and is not correctable with lenses. It can result from any condition that prevents the eye from focusing clearly, especially the inability of one eye to focus as good as the other eye. It usually develops before the age of 6. It often appears in persons with strabism or big difference in the refraction. Functional monocularity because of strabism and amblyopia right eye Monocularity Requirements Class 2 Better eye distant visual acuity > 1,0 uncorrected or corrected A period of adaptation time has passed from the known point of visual loss Monocular visual field normal Meets the standards for near and intermediate visual acuity No significant pathology Satisfactory medical flight test Medical Flight Test CAA UK TO ASSESS SAFE HANDLING AND FITNESS TO OPERATE ALL AIRCRAFT CONTROLS a) IN NORMAL FLIGHT CONDITIONS (pre flight checks, preparation for flight, taxi, take off, landing, normal flight manouvers and operation of all switches, levers and other operational procedures in the cockpit) b) IN THE EVENT OF AN EMERGENCY (e.g. engine failures, brake faults requiring full manual braking, rejected take off following engine failure) c) IN DEMONSTRATING SAFE EVACUATION OF THE AIRCRAFT