1. Computer Analyzer for Field of Vision
Giorgi Gigilashvili, PhD student at Deparment of Biomedical Engineering, Georgian Technical University
Supervisor: Prof. Zviad Gurtskaya
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

2. History 1945 – First perimeter system designed by Goldmann
1970 – Octopus perimeter was first introduced
1982 – Humphrey field analyzer displayed at AAO
1983 – First clinical trials showed by Michael Patella
1984 – Became popular in clinical environment
First of all let me pinpoint the major facts in the history of field of vision examination and evolution of perimetry systems that took place in the past 50 years. In 1945 Swiss ophtalmologist Hans Goldmann (born in 1899) introduced the design of first perimeter system. Later in 1970 professor Franz Frankhaus with his group of young scientists proposed static perimeter system which was subsequently introduced on the market in saw an announcement of Humphrey field analyzer at American Association of Ophtalmologists (AAO), which remains one of the most widely used type of perimeter system nowadays. Michael Patella conducted the first clinical trials with perimeter system in 1983 while after 1984 perimeter system became a popular tool for analysis of field of vision and assessment of various ophtalmological and neurological diseases.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

3. Perimetry
Perimetry is the measurement of visual functions of the eye at topographically defined centers in the visual field
Perimetry is a type of ophtalmological examination during which the measurement of visual functions of the eye at topographically defined centers in the visual field is performed.
Usually each is tested separately, however when both eyes are tested together the field of vision we assess is called the binocular field of vision which expands at in size. A roughly circular area is common to both eyes.
Background luminance, which is one of the major factor of the system, for currently exploited perimeter system is 31.5 asb (Apostilb) that is approximately 10 cd/m2.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

4. Uses of Perimetry Glaucomatous field defects Chorioretinal lesions
Optic disc lesions
Optic nerve lesions
Neuro-ophtalmic lesions
As mentioned before, perimeter system is used to detect and assess various ophtalmological and nuerological disorders like:
The normal human visual field extends to approximately 600 nasally (towards the nose), approximately 1000 temporaly, approximately 600 superior (towards the head) and 750 inferior (towards the feet).
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

5. Techniques of Visual Field Analysis
Visual field can be charted by using kinetic and/or static techniques with instruments that are operated either manually or automatically (computerized)
There are two types of perimetry techniques that have been used over the period of time: Kinetic and static techniques. Visual fields can be charted by using both techniques with instruments that are operated either manually or automatically.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

6. Kinetic Perimetry Kinetic Perimetry (Manual)
Stimulus is moved from a non-seeing area to seeing area to the point at which it is firstly observed by the patient in relation to fixation point.
The operator selects the stimulus (target), size and intensity, moves the target from periphery close to central area of eyesight, monitors patient eye fixation.
Examination with kinetic perimeter technique represents the procedure throughout which the stimulus (target) is moved from a non-seeing area to seeing are to the point at which the test object can firstly detect it in relation to fixation point.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

7. Static Perimetry Static Perimeter Computerized
Static technique involves the presentation of static test objects
Static method represents an “on – off” technique during which each stimuli is presented to the patient for the duration of second and the points (targets) which patient failed to detect are recorded.
In contrast to kinetic perimeter, static technique is an automated method of examination during which the targets are presented in stationary mode. Static method represents an on and off technique in which each stimuli from different location of field of vision (target) is presented to the testing object for the duration of seconds and the points (targets) which patient failed to observe are recorded for software analysis and presented at the end of the examination.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

8. Parameters of Perimetry
Instrument Variables:
Stimulus size
Stimulus duration
Background Luminance
In static perimetry the following factors influence the visibility of white target:
Size/diameter/area of the target spot
luminous intensity of the target spot
Background illumination
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

9. Kinetic VS Static Perimetry
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

10. Computed Perimetry System for Visual Field Testing
Let me present you computed static perimetry system that was designed and engineered at Biomedical Engineering Department of Georgian Technical University.
The Computer-Controlled System for Diagnosing the Field of Vision offered by us is intended for carrying out diagnosis of the central as well as peripheral part of a field of vision with the use of the monitor of a personal computer for displaying the chart of field of vision. It can be applied to carry out researches both in stationary and out-patient conditions.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

11. Computed Perimetry System for Visual Field Testing
Hemisphere
Control module for stimuli presentation
Diagnostic module
Patient gaze fixation control module
The system consists of four basic modules:
The perimeter’s bowl is made of lightweight plastic material. White light emitting diodes are used as a source of stimuli (target). Bowl incorporates 216 LED-s that are located in the back part of the hemisphere along 24 meridians and are united in 10 groups.
The control module which incorporates PC and integrated software module provides control of representation of light stimulus of various parameters that are defined by performing physicians.
The diagnostic module provides an opportunity to receive the diagnostic data in digital format as well as store them future analysis and comparison.
The patient’s gaze monitoring module is equipped with a tiny video camera in order to discern the moments when patient diverts his sight from fixed position and sends the information to diagnostic module to exclude the misinterpreted data from subsequent pre-processing. System memorizes and stores the specific number of the LED which was a source of stimuli that the patient dropped (did not observe correctly due to diversion of sight) and towards the end of the examination an above mentioned stimuli is repeated in order to acquire the full set of data for field of vision chart generation process.
Presented at 6-th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

12. Computed Perimetry System for Visual Field Testing
The electric scheme of connections of light-emitting diodes represent a matrix 10 x 24 which will demand the presence of the switching device with 34 outlets. For the reduction of the quantities of connecting conductors and outlets of the switching device, we use a matrix of connections 10 x 12, in the knots of which there are two light-emitting diodes in parallel gears.
Electric scheme of connections of light-emitting diodes
Presented at 6-th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

13. Computed Perimetry System for Visual Field Testing
As a switching device microcontroller PIC16 F887 is applied. The microcontroller having 5 ports in number, provides commutation of a matrix of light-emitting diodes, connection with the personal computer and information input. Besides the microcontroller, the switching device contains a voltage stabilizer 5V.
Main Switching Board with Microcontroller PIC16 F887
Presented at 6-th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

14. Computed Perimetry System for Visual Field Testing
The basic scheme of the device of switching is shown above.
Software module transmits the data about the brightness level defined for each LED and about the number of LED to be switched on to the microcontroller. The microcontroller having processed the received information, performs corresponding actions and submits them to the necessary levels of architecture.
Brightness control of a luminescence of light-emitting diodes is carried out by the pulse-width modulation.
Recording the detection of stimulus presented by LED-s by patient is performed by pressing the joystick button which is connected to one of microcontroller outlets. The system works on the basis of PC, the software module is carried out by the programming language Quick BASIC, in the environment of Visual Studio. The module for the detection of the movements of eyes is developed in program language C#.
Basic Scheme of Switching Device
Presented at 6-th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

15. Computed Perimetry System for Visual Field Testing
Microcontroller PIC16 F88 Specifications
Presented at 6-th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

16. Computed Perimetry System for Visual Field Testing
Eye Pupil Movement Controlling Module
(Gaze fixation monitoring module)
Monitoring and control of eye pupil movement is performed by built in video camera
Coordinates of eye pupil location during the start of examination are stored in the database
During the examination process eye pupil location is constantly compared to stored data to discern eye movement
Fixation is also tested by mapping of the blind spot
In order to detect the pupil movement the perimeter system is equipped with tiny video camera which is managed by controlling module. At the start of each examination the controlling module stores the coordinates of eye pupil location and throughout the entire examination process pre-stored location is constantly compared to current eye pupil location.
Each eye has a physiological blind spot at the optic nerve head, where the absence of photoreceptors produces an absolute scotoma roughly 10-15º temporal to the fovea. Fixation can be tested by mapping the blind spot, and then retesting the blind spot throughout the visual field test. Positive responses during retesting of the blind spot are assumed to reflect loss of fixation.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

17. Computed Perimetry System for Visual Field Testing
Eye Pupil Movement Controlling Module

18. Current and Future Plans
Modification and upgrade of current computed perimetry system
Integrated PC
Integrated touch screen monitor
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

19. Current and Future Plans
Mini PC x86 L-20Y D525
We are planning and currently working on the idea to make some improvements by integrating the mini PC module which will handle the operations that is now being performed by the stand alone personal computer. This will reduce the bulk size of the system and will make the perimeter system even more portable, while the wireless architecture will further enhance its user friendly attitude.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

20. Current and Future Plans
Mini PC Specifications:
CPU
INTEL D525 ATOM Dual core 1.8 MHz
RAM
DDR3 SO-DIMM (2GB)
Dimension
19.7 X 19.7 X 4cm
Graphics
Integrated intel®3150(GMA3150)graphics
Hard Drive
128 GB
Resolution
1366x786, 1024x600, 800x600, 640x480
Weight
2.5 KG
Supported OS
WIN7, Linux, Windows XP,  Ubuntu,Debian 
I/O Ports:
4 x USB, VGA, MIC, SPK, RJ45 LAN
RS232
YES
WIFI
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

21. Current and Future Plans
10 inch touch screen monitor
We are planning and currently working on the idea to make some improvements by integrating the mini PC module which will handle the operations that is now being performed by the stand alone personal computer. This will reduce the bulk size of the system and will make the perimeter system even more portable, while the wireless architecture will further enhance the user friendly attitude.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

22. Current and Future Plans
Mini PC Specifications:
Scren size
10 Inch
Color
Multicolor
Screen Ratio:
4 X 3
Touch signal input
RS232 or USB
Touch sensibility
>3mm
Response Time
< 16 mS
Optimal resolution
1024 x 768, 800 x 600
Brightness
350 cd/m2
Signal input
DVI or VGA
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

23. Computed Perimetry System for Visual Field Testing
Advantages of Computed Perimetry
System for Visual Field Testing
The data is quantifiable, reproducible and amenable for statistical manipulation
An automated technology reduces the need for highly trained technicians/operators
Elimination of outcomes of possible subjectivity of perimetrist and/or patient
Automated perimetry is more accurate and informative
Simplicity and availability of the System allows its use in out-patient conditions.
Integrated network module provides an opportunity to transfer the examination data and chart to the remote centralized database for ophtalmologists so that they can recommend either the medicaments for the treatment or operative intervention;
The system gives a wide choice of parameters and conditions for carrying out the researches, and also the possibility of program adjustment under the concrete monitor. All the measured values and options remain in a database.
While carrying out a concrete research, the System can operate with the following parameters: distance from an eye to the screen; an eye (OD, OS); color of a background; color, size and delay time in a stimulus presentation; color, size, whether a fixed point blinks or not; time of eye’s adaptation to the experimental conditions; the measurement scheme; number of control measurements; delay time between a presentation of various consecutive stimulus.
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

24. Computed Perimetry System for Visual Field Testing
International Education Fair, Tbilisi 2014
Independence Day, Tbilisi 2014
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

25. Computed Perimetry System for Visual Field Testing
THANKS
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia

26. Computed Perimetry System for Visual Field Testing
Questions and Discussion
Presented at 6th Georgian-German School and Workshop in Basic Science, July 2014, Tbilisi, Georgia