Ebook Principles and practice of aviation medicine: Phần 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook Principles and practice of aviation medicine: Phần 2
Ebook Principles and practice of aviation medicine: Phần 2
Chapter 17Ophthalmology for the Medical ExaminerRudiger Schwartz* *'* and Jorg Draeger*INTRODUCTIONOver 90% of flight-relevant information comes to th Ebook Principles and practice of aviation medicine: Phần 2he pilot through the eye, making it the most important sensory input system for aviators. Despite technological advances in aircraft engineering and information technology, nothing has changed in that regard. On the contrary, research is being undertaken to transfer even more flight-relevant informa Ebook Principles and practice of aviation medicine: Phần 2tion from the aural into the visual realm. With the introduction of "fly-by-wire" technology, even residual mechanical input is slipping away; neitherEbook Principles and practice of aviation medicine: Phần 2
stick pressure nor power setting changes are noticeable by feel or hearing when the Flight Management System (FMS) activates its programmed settings,Chapter 17Ophthalmology for the Medical ExaminerRudiger Schwartz* *'* and Jorg Draeger*INTRODUCTIONOver 90% of flight-relevant information comes to th Ebook Principles and practice of aviation medicine: Phần 2e aircraft.1 Developments in recreational flying are heading in the same direction, with display panels becoming similar to those of corporate aircraft. Even high performance airplanes, although not flown by an FMS, nonetheless have relatively large instruments displays that are not only designed fo Ebook Principles and practice of aviation medicine: Phần 2r navigational purposes but are also linked to flight data recorder information. The pilot can only utilize the displayed information if he can discerEbook Principles and practice of aviation medicine: Phần 2
n the information precisely.*Corresponding author.*Department OÍ Ophthalmology, Hamburg University, Hamburg, Germany, E-mail: r.schwartz@yke.uni-hambuChapter 17Ophthalmology for the Medical ExaminerRudiger Schwartz* *'* and Jorg Draeger*INTRODUCTIONOver 90% of flight-relevant information comes to th Ebook Principles and practice of aviation medicine: Phần 2roduce an unambiguous signal image, which is transmitted to the optical cortex for interpretation and reaction. As in all of our sensory systems, a certain stimulus size must be exceeded in order to be perceived. In physiology, this is termed "threshold." This does not necessarily have to do with en Ebook Principles and practice of aviation medicine: Phần 2ergy levels, such as the quantum amount required to sense light, but rather with the resolution limits for distinguishing geometric patterns. On the oEbook Principles and practice of aviation medicine: Phần 2
ne hand, the cockpit signals must be designed such that they exceed the threshold for perception, and on the other hand, the receptor (the eye) and itChapter 17Ophthalmology for the Medical ExaminerRudiger Schwartz* *'* and Jorg Draeger*INTRODUCTIONOver 90% of flight-relevant information comes to th Ebook Principles and practice of aviation medicine: Phần 2cuity" is defined as the ability to discriminate a single point. This can be important in aviation, such as when a distant aircraft can be discerned as only a point. In clinical practice, however, point visual acuity is not measured quantitatively."Visual acuity of separation," or minimum angle of r Ebook Principles and practice of aviation medicine: Phần 2esolution, describes the ability to discriminate two closely neighboring points as separate. This is the conclusive criterion for signal perception."VEbook Principles and practice of aviation medicine: Phần 2
isual acuity of localization" is defined as the smallest recognizable change in spatial relationships between two objects. An example is the so-calledChapter 17Ophthalmology for the Medical ExaminerRudiger Schwartz* *'* and Jorg Draeger*INTRODUCTIONOver 90% of flight-relevant information comes to th Ebook Principles and practice of aviation medicine: Phần 2ernier scale. It is possible to determine inaccurate positions at less than 10 seconds of arc."Visual acuity of recognition" (minimum legible acuity): the point at which an object can be perceived as such. This is within the realm of cognition.The resolution of the eye is the visual acuity of separa Ebook Principles and practice of aviation medicine: Phần 2tion as given by the smallest angle subtended by two points still visible as separate. This angle is called the "minimum angle of resolution" (MAR) anEbook Principles and practice of aviation medicine: Phần 2
d is measured in minutes of arc. The visus is defined as the reciprocal of this threshold angle, measured in minutes of arc. Visus I means the MAR is Chapter 17Ophthalmology for the Medical ExaminerRudiger Schwartz* *'* and Jorg Draeger*INTRODUCTIONOver 90% of flight-relevant information comes to th Ebook Principles and practice of aviation medicine: Phần 2p between Snellen notation, MAR, logMAR, and decimal notation:Snellen NotationMetricImperialMARlogMARDecimal2206820/2001010.11768520/16080.90.131403220/1256.30.80.164510720/10050.70.24510120/8040.60.254509620/603.20.50.324509220/502.50.40.44508920/4020.30.56/9.520/301.60.20.636/7.520/251.250.10.8450 Ebook Principles and practice of aviation medicine: Phần 28320/201016/4.820/160.8-0.11.256/3.820/12.50.63-0.21.586/3.020/100.5-0.32Many individuals, especially young people, possess a visus of >1. In other woEbook Principles and practice of aviation medicine: Phần 2
rds, the MAR is significantly smaller than one minute. Examination is usually performed using test letters with defined identifiable angles in the shaChapter 17Ophthalmology for the Medical ExaminerRudiger Schwartz* *'* and Jorg Draeger*INTRODUCTIONOver 90% of flight-relevant information comes to th Ebook Principles and practice of aviation medicine: Phần 2ut 1° of the fovea centralis is needed. If the image drifts onto the retinal periphery, the resolution will deteriorate exponentially. At a distance of 20 cm from the eye, the area of clarity has a diameter of about 3.5 mm, while at a distance of a meter, this area enlarges to 17 mm. It is therefore Ebook Principles and practice of aviation medicine: Phần 2 not possible to visualize two flight deck instruments simultaneously with full resolution, whether they are next to each other or at different distanEbook Principles and practice of aviation medicine: Phần 2
ces. To achieve this, eye movements are needed. These are very fast and are directed with considerable accuracy, but this requires a distinctly structChapter 17Ophthalmology for the Medical ExaminerRudiger Schwartz* *'* and Jorg Draeger*INTRODUCTIONOver 90% of flight-relevant information comes to th Ebook Principles and practice of aviation medicine: Phần 2rrors than one where the units are markedChapter 17Ophthalmology for the Medical ExaminerRudiger Schwartz* *'* and Jorg Draeger*INTRODUCTIONOver 90% of flight-relevant information comes to thGọi ngay
Chat zalo
Facebook