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 INTRODUCTION: Eyes are the most important organ of ourhuman body as they provide vision to our brain for the understanding andformation of the objects and things around us. Every organ in the body tends todeteriorate, so does the eye. The difficulty that arises is the poorer visualacuity of the eye, whether it is said to be nearsightedness or farsightedness.The patients suffering from myopia (nearsightedness) can see distant objectsclearly but face difficulty in viewing the nearer objects. The patientssuffering from hyperopia (farsightedness) can see near objects clearly, but thedistant ones are not clear. The basic device used for the correction of theseaberrations is a phoropter device, that has a series of multiple lenses thatare switched before the patient eye, the lens that provides better vision isprescribed by the optician.

The values of these aberrations are given inspherical and cylindrical lens power. Nearsighted has minus in their value,while farsighted has positive in their value.Keeping in mind the following eyeproblems, the first device made was a manual phoropter it has a huge structurethat was not mobile. It was created by Henry De Zeng in 1921. The common nameused for the ophthalmic device is Refractor.

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It is a medical device used by eyecare professionals. The procedure starts as the person sits behind thephoropter and looks through it at an eye chart known as Snellen’s chart that isplaced at a fixed distance (6m or 20ft). The optician changes the power oflenses according to the subject’s feedback. When the person’s vision has beencorrected then the optician prescribed the number of the lenses.

The main idea of our project is to make adevice which can go into remotely visited areas. Our device is AutomatedPhoropter Device which works on the principle of bifocal lenses. The idea ofminiaturizing this device is to make it portable and accessible to unprivilegedpeople. The design made is very simple and comparatively precise andconstructed using basic optical and engineering techniques.

The main componentof the device are bifocal lenses which has a range of -6 to +3 diopters. Thedriving mechanism is controlled by micro controller Arduino with two multiturnpotentiometers connected to its respective lenses. On each side of the framedesign two knobs are attached for the movement of lenses. The lenses slide overas the knob is rotated. Each user accommodates their vision according to theiracuity and the reading in diopters is shown on the LCD.                   BACKGROUND ANDTHEORY: During the 17th century, lenses were themain source to determine the optical correction and relied upon subjectivefeedback. Since the 1800’s, practitioners of clinical refraction have beentrial lenses withobjective or subjective techniques to arrive at a final refractivecorrection.

 The scope of optometry expanded, but the subjectiverefraction remained a major part of the vision examination. In 1915, Baush and Lomb started to maketrial cases (known as the precision trial case) and trial frames. The precisiontrial case lenses had a diameter of only 15 mm.The first phoropter that in any wayresembled today’s phoropters was developed by De Zeng.

Most modern refracting units containthe sphere and cylindrical lenses on three discs. The wheel closestto the patient’s eye usually contains the high-power spheres, the second disccontains the low power sphere and the third disc contains the cylindrical lenses.1Initially, the phoropters made consistedof many parts and were complexed.

The main idea behind this invention was tocorrect the eye problems that prevailed among the population. It still servesthe same purpose.  But the componentshave been short down to few. But the structure remains the same.

                                PHYSIOLOGICALASPECT: Being a perishable organ, eye, has thetendency in itself to deteriorate due to various biological , environmental andphysiological hazards. The most common problems that arises due to any externalfactors or aging are farsightedness(hyperopia) and nearsightedness(myopia).Common symptoms of myopia include:·      Blurry vision·      Headaches from eyestrain·      Trouble seeing at night·      Difficulty driving or navigating·      Frequent squinting·      Double visionMyopia is treated with improvement invision.

Common types of myopia treatment include:·      Prescription eyeglasses·      Refractive Eye Surgery·      Intraocular lens implants (IOLs)·      Contact Lenses·      LASIK SurgeryHyperopia is an eye defect dueto which patients cannot see the near objects clearly.Farsighted typically have symptoms suchas:·      Blurryvision·      Squinting·      Eyestrain·      Itchy,burning eyesFarsightedness is a common eye-healthproblem in the world. The treatment options that are available are as follows:·      Prescriptioneyeglasses·      Prescriptioncontact lenses·      LASIK·      Refractivesurgery    EXPERIMENTALTECHNIQUE: Our automated phoropter device is based ondual power lenses technique. The two lenses are attached and overlaps eachother.

Each lens is divided into half concave and half convex part that whenslides over each other changes the power. The power ranges from -6 to +3diopters (Diopter being the unit of optical power).  This technique was first developed by a Nobelprize holder Alvarez, the technology so named Alvarez technique. After manyyears from the invention of this technology it was finally adopted byoptometrist and ophthalmologist to be used as a tool for treating eye aberrations.

the reason that this technology was theoretical, and the practicalimplementation of this technology was impossible due to the fact that theselenses were very complex and cannot be fabricated. Variable-power spherical lens is composed of two thin lenselements arranged in tandem, one behind the other along the optical axis of thelens system, the optical axis being substantially normal to the lens surfacesand passing substantially through their centers. At least one of these lenselements is movable in a direction transverse to the optical axis, andpreferably both lens. Even if both lens elements move, non-variable lenses canfrequently be added to either one or both of the variable lens elements byvariation of their optional terms, if it is desired to do so 2.The Alvarez technology has been adopted in various optical systems as well.they are frequently used in optical lenses of digital cameras such as DSLR etc.    Figure 1. Principle of Alvarez LensTechnology           METHOD: A typical phoropter is alarge device consisting of variable power lenses that provides cylindrical andspherical powers.

The procedure starts as the optometrist placed the device infront of the patient, who is compelled to respond the optometrist as theletters on the chart (placed at a specified distance) start to get clearer asthe lenses in the phoropter are adjusted i.e. it is an iterative procedure.  The trialframe containing several lenses can become painfully heavy, especially forolder patients.

According to the lens value andreadings, eye prescription is given.Our automated phoropterdevice design is smaller in size, and the procedure can be performed by theindividual himself. It consists of a pair of bifocal lenses that ranges from -6to +3 diopters.

The bifocal lenses work on the slide over mechanism. Therotatory knobs present at each side of the device helps the user to change thepower of the lenses according to their vision acuity.The rotatory motion iscontrolled by a potentiometer which is further connected with gears thatcorresponds to the power of lenses in accordance with the number of rotation.

One rotation is equal to 0.1 diopter value. The rotations are controlled by theuser with the help of the rotor regulators placed on each side of the frame. Eachregulator is responsible for the power changes in the lens of its respectiveside.As the desired acuity isreached the values in both the lenses are displayed on the lcd.                          TECHNICALSPECIFICATION: This section provides thetechnical design specifications of our device. It contains details for allmajor functional parts of the device. Lens power (sphero-cylindrical range) -6 to +3 diopters Lens length 49mm Lens thickness 2 mm each Pupillary distance 63mm Vision test type Distant and near Calibration requirement  None Power requirement Battery operated Processing unit Microcontroller Fixation Not required Design Head mounted Reading distance 6/6 meter, 20/20 feet Set up time                                                                      20 seconds                 HARDWARE:COMPONENTS OF THE PROJECT:1.

MULTITURN POTENTIOMETER:Multiturnpotentiometers are controlled by shaft which is rotating, but by several turnsrather than less than a full turn. We are using a multiturn potentiometerhaving a rotation of 10 turns.Precisionpotentiometers are designed for control applications where accuracy andhigh-reliability is important. These devices are available in conductiveplastic, wire wound or Hybritron element types, and in various sizes. Bothsingle-turn and multiturn models are available. Typical applications includemeasuring linear distance, angles or rotations in production equipment,industrial test and measurement equipment, and medical equipment. 32.

GEARS:A toothed machine part,such as a wheel or cylinder, that meshes with another toothed part to transmitmotion or to change speed or direction. 4Gears change thedirection and speed of rotation. it is used for transmitting power from onepart of a machine to another. The main purpose of using gear isto change therotational speed of the output shaft with respect to the input shaft.3. LCD:The 16×LCD is a verybasic show module.

The 16×2 Lcd gives a display of 16 characters each line in 2such lines. In this LCD each character is displayed in 5×7 pixel matrix. ThisLCD has two registers, namely, Command and Data.

The command registerstores the command instructions given to the LCD. A command is an instructiongiven to LCD to do a predefined task like initializing it, clearing its screen,setting the cursor position, controlling display etc. The data register storesthe data to be displayed on the LCD. 54. ARDUINO UNO:The Arduino Uno is amicrocontroller board based on the AT mega 328 . This microcontroller is whatexecutes the instructions in your program. The ATmega328 microcontroller is theMCU used in Arduino UNO R3 as a main controller. ATmega328 is an MCU from theAVR family; it is an 8-bit device, which means that its data-bus architectureand internal registers are designed to handle 8 parallel data signals.

65. POLY ACRYLIC PLASTIC BODY:The plastic body cansimply be formed into desired shape.6. SWITCHES:These are used forturning the power on and off.7. KNOBS:It is used forcontrolling the device operation.

Control knobs are used for the control oradjustment of electronic or electrical devices. They are often referred to asinstrument knobs, electronic knobs, or electrical knobs. Control knobs providemachines or instruments with precise position adjustments and controlled levelsof circular motion. They may be marked with graduations in the form of lines ornumbers to provide reference points for adjustments.

Control knobs are usuallymade of metal, plastic, or rubber              MARKED FEATURES:·       It has a distinctive and ultra-portable design.·       It is easily affordable and easily transportable due to itslight weight and compact design to the under privileged areas of the country.·       It is extremely user friendly, the design omits the need of asupporting structure.

·       The control buttons present on each side of the phoropterallows the user to navigate according to their visual acuity.·       It delivers highest level of accuracy, the head mounteddesign fits efficiently over the head of the user, thus, gives correct eyepositioning and reduces the odds of error.·       It doesn’t require substantial training or a specialized widespace for the placement.

·       It offers adaptable technology for eye aberrationsmeasurement and calculation.·       It has a corrosion-resistant material.                             OPERATINGINSTRUCTIONS: STEP 1:The person has to sit at a distance of 6mor 20 ft from snellen’s chart or any object that is at a required distance.

STEP2:The individual positions the phoropter andmounds over his head. The phoropter is adjusted in such a way that his headshould be kept straight.STEP3:After adjusting the phoropter, the shutterpresent at the front must be moved to one extremity whether right or left suchthat it blacks out one eye means the other eye is ready to be tested.STEP4:The individual starts rotating the knoband the lenses starts to slide over each other.

As the vision gets cleared thelens power is displayed on the LCD.                                                                           SIMILARINVENTIONS: Since the 1800,many different kinds of phoropters are being invented that are driven bydifferent principles to enhance its use and to provide better welfare for humanbeings. The major drawbacks with the earliestinventions are their huge mechanical structures that requires space and properfixations, be it any device. Initially, the phoropters made were very spaceconsuming and had a lot of parts in them. From an article we found one more invention ofcompact fluidically controlled phoropter.

It has adjustable astigmatic anddefocus lenses. Contrary to our device, the lenses of this device have nomechanical movement, they are controlled by using different fluids andexperimented upon an artificial eye with induced aberrations. Incorporation of fluidic lenses into thephoropter will allow a continuously varying optical wavefront that results inreduction of the time required for the examination, since the process could becomputer controlled. The physical size and complexity of the standard phoropteris problematic from a manufacturing and deployment perspective, and thedevelopment of a fluidic lens system offers the potential to simplify andgreatly reduce the size of the instrument. Fluidic lenses that arebased on a flexible membrane use fluidic pressure to control the curvature ofthe flexible membrane.

This control allows alteration of the optical wavefrontin a continuous and consistent manner 7.The phoropter is composed of one defocus lens andtwo astigmatic fluidic lenses that work in unison to provide arbitrarysphero-cylinder refraction. Each of the lenses is composed of an elasticmembrane that is secured with a metallic retaining ring and contains a 12.5 mmglass rear surface, which is the clear aperture of the lens.

A separate fluidreservoir is present for each lens that is 1.65 mm thick and allows independentcontrol of the lenses. Adding or removing fluid from the chamber allows thedefocus lens to provide both positive and negative optical power. The defocuslens has a circular restraining aperture of 23 mm in diameter, which is used tosecure the elastic membrane. The astigmatic lenses have a rectangular retainingring that results in a restraining aperture of 30.0 mm×16.

0 mm, which is usedto secure the elastic membrane. The axes of the two astigmatic fluidic lensesare oriented at 45° to each other. 8               RESULT: The most important aspect of the result issampling. Carrying out trials to examine the accuracy and precision is anessential part of any medical device as it is directly implemented on humanbeings. Even the minor probability of any flaw can cause life altering threatsto the patient. To minimize these threats and to gain accuracy we arrangedscreening for over 20 persons suffering from eye defects. Most of them whichwere nearsighted that is they have myopia.

Screening as a medical term is a wayof identifying the chances of an undiagnosed disease. The results are shownbelow the table.   NAME AGE (Years) EYE PRESCRIPTION (LEFT)   (RIGHT) DEVICE READING (LEFT)   (RIGHT) POSSIBLE HUMAN ERROR Dr. Asif 40 -3.

5 D -3.5 D -3.5 D -2.95 D  -0.55 Salman Marfatiya 30 -0.9 -0.6 -0.97 -0.

6 0 Abdul Moid 22 -1.7 -1.7 -1.

7 -2.06 -0.36 Owais Malik 22 -2 -2 -2.

23 -2.5 -0.23,-0.

5 Hamza khan 22 -1 -1 -0.85 -0.88 -0.15,-0.12 Aimen Haseeb 22 -2.5 -2.5 -2.

45 -2.4 -0.05,-0.1 Areeba Farooqui 23 -2.25 -2.75 -2.27 -2.64 -0.

02,-0.11 Taha Mushtaq 25 -0.75 -1 -0.5 -0.98 -0.25,-0.02 Sheikh Hasan 23 -1.5 -1.

25 -0.94   -1.12 -0.56,-0.13 Rafay Shamshad 23 0 0 0 0 -0 Rida 23 0 0 0 0.32 -0.32 Maira Najeeb 23 -1.75 -1.

75 -1.75 -1.53 0.2           CONCLUSION: The entiremaking and arrangements of minute details and components has made possible thisdevice. The core idea behind its invention was the welfare of human beings.Every medical institution and facility strives for the betterment and providingthe best of their services to benefit the suffering ones.

Uncorrected eyevision is one of the main cause for blindness. Neglection and lack of medicalfacilities result in improper or sometimes, no treatment.According to GLOBAL INITIATIVE FOR THEELIMINATION OF AVOIDABLE BLINDNESS by world health organization ‘Of theestimated 45 million cases of blindness by 1996, approximately 60% were due toeither cataract (16 million people) or refractive errors’. 9The miniature and compact size of thisdevice make it portable and mobile to be transported in every corner of theglobe, benefitting the human race. Refractive errors, during the initial periodare not a life-changing threat, but as it remains undiagnosed and untreated, itbecomes perilous for that person.Refractiveerrors (myopia, hypermetropia, astigmatism, presbyopia) result in an unfocussedimage falling on the retina. Uncorrected refractive errors, which affectpersons of all ages and ethnic groups, are the main cause of visual impairment.There are estimated to be 153 million people with visual impairment due touncorrected refractive errors, i.

e. presenting visual acuity < 6/18 in thebetter eye, excluding presbyopia. 10.                      FUTURE WORK: There is a widefuture progress in the field of optics and this device particularly. Everydevice that has ever been made had rooms for improvement. Addition of moderntechnology and advent of latest techniques and idea has always helped scientistand researchers to put forward more effort and going an extra mile.

The future workthat can be done in this device is as follows:·       Thesize can be further miniaturized·       Anaddition of Bluetooth technology will enhance it working·       Gsmsystem can be incorporated·       Additionof more gears to make results more precise and accurate·       Automaticdrivers and remotes can be added to make it more automated                                                      REFERENCES: 1 https://www.scribd.com/doc/19428106/Phoropter-Handouts 2 https://www.google.com/patents/US3305294 3 http://www.

bourns.com/products/potentiometers/precision-pots-multiturn.4 https://www.thefreedictionary.com/gear 5https://www.engineersgarage.

com/electronic-components/16×2-lcd-module-datasheet6 https://www.allaboutcircuits.com/technical-articles/understanding-arduino-uno-hardware-design7-8 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2845967/ 9 http://www.

who.int/blindness/Vision2020_report.pdf10 http://www.who.

int/blindness/Vision2020_report.pdfFigure 1. https://adlens.com/technology/alvarez-lens/  

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