Adaptica 2WIN-S User manual

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2WIN-S
2WIN-S Plus
OPERATOR MANUAL

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Revision notes
Software configuration version
2WIN/2WIN-S 5.6.0
Publication date
2022/02/17
Hardware configuration
Version 37.1
Rev Num.
10.0_EN
General notes
Family: 2WIN VISION ANALYZER
Family intended use: Portable instruments for the measurement of binocular and monocular
refraction based on infrared photorefraction
Models: 2WIN, 2WIN-S, 2WIN-S PLUS

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Summary
REVISION NOTES......................................................................................................................................................... 2
GENERAL NOTES ......................................................................................................................................................... 2
SUMMARY ............................................................................................................................................................. 3
1MANUFACTURER IDENTIFICATION .................................................................................................................... 5
2LEGEND OF SYMBOLS ........................................................................................................................................ 5
3INTENDED USE OF THE DEVICE .......................................................................................................................... 6
4CLASSIFICATION AND APPLIED STANDARDS ...................................................................................................... 6
CLASSIFICATION ACCORDING MDD 93/42/EEC, ANNEX IX, AND MDR 2017/745 EU, ANNEX VIII ................................................6
CLASSIFICATION AND TYPE OF APPLIED PARTS............................................................................................................................6
IP CLASSIFICATION............................................................................................................................................................... 6
ELECTROMAGNETIC COMPATIBILITY ........................................................................................................................................6
APPLIED STANDARDS............................................................................................................................................................6
5PRECAUTIONS ................................................................................................................................................... 7
6QUICK USER GUIDE............................................................................................................................................ 9
6.1 MAIN APPLICATIONS ....................................................................................................................................................9
6.2 EXAM CONDITIONS.......................................................................................................................................................9
6.3 MEASUREMENT TIPS...................................................................................................................................................10
7DESCRIPTION OF THE DEVICE............................................................................................................................10
7.1 2WIN AND 2WIN-S.................................................................................................................................................. 10
7.2 2WIN-S.................................................................................................................................................................. 10
7.3 PACKAGE LABELLING................................................................................................................................................... 12
7.4 2WIN-S LABELING.....................................................................................................................................................13
7.5 INTERFACES ..............................................................................................................................................................15
8OPERATIVE INFORMATION...............................................................................................................................16
8.1 OPERATING CONDITIONS .............................................................................................................................................16
8.2 UNPACKING..............................................................................................................................................................17
8.3 ACCESS TO 2WIN...................................................................................................................................................... 17
8.4 BEFORE OPERATION ................................................................................................................................................... 18
8.5 DATA MANAGEMENT DISCLAIMER .................................................................................................................................18
8.6 IMPORTANT NOTES ON BATTERY ...................................................................................................................................18
9OPERATIVE INSTRUCTIONS...............................................................................................................................18
9.1 DEVICE SETUP ........................................................................................................................................................... 19
9.2 PREPARATION OF THE PATIENT .....................................................................................................................................20
9.3 MEASUREMENT......................................................................................................................................................... 21
9.4 SAVE EXAM............................................................................................................................................................... 27
9.5 GAZE.......................................................................................................................................................................28
9.6 CUSTOMIZATION........................................................................................................................................................28
10 WIRELESS CONNECTIONS..................................................................................................................................29

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10.1 BLUETOOTH CONNECTIVITY........................................................................................................................................ 29
10.2 WI-FI CONNECTIVITY ................................................................................................................................................29
10.3 PAIRING AND TRANSFERRING A 2WIN-S EXAM TO VISIONFIT SC ......................................................................................30
11 REMOTE CONTROL: 2WIN APP-CONNECTION WI-FI..........................................................................................33
12 REMOTE CONTROL: KALEIDOS APP...................................................................................................................33
12.1 KALEIDOS APP:INSTALLATION AND CONFIGURATION.................................................................................................... 34
12.2 REVIEW EXAMS USING KALEIDOS APP........................................................................................................................36
12.3 KALEIDOS APP:SETTINGS........................................................................................................................................37
13 2WIN-S PLUS (PACKAGE) ..................................................................................................................................39
13.1 AI-APP:ANOMALIES DETECTION HINT OF ANTERIOR SEGMENT .........................................................................................39
13.2 CR-APP:CORNEAL REFLEXES APPLICATION....................................................................................................................41
13.3 EMR CONNECTION SET-UP ........................................................................................................................................47
14 SOFTWARE UPDATE INSTRUCTIONS .................................................................................................................50
14.1 MANUAL UPDATE PROCEDURE....................................................................................................................................50
14.2 AUTOMATIC UPDATE PROCEDURE................................................................................................................................50
15 DISINFECTION...................................................................................................................................................51
16 MAINTENANCE AND CLEANING INSTRUCTIONS................................................................................................52
16.1 HOW TO CLEAN THE SYSTEM ......................................................................................................................................52
16.2 STORAGE INSTRUCTIONS............................................................................................................................................52
16.3 INSTRUCTIONS FOR THE CORRECT DISPOSAL OF THE DEVICE...............................................................................................52
16.4 INSTRUCTIONS FOR CORRECT DISPOSAL OF 2WIN-S PACKAGING ....................................................................................... 52
16.5 SEPARATE COLLECTION FOR ELECTRICAL AND ELECTRONIC EQUIPMENT................................................................................52
17 TROUBLESHOOTING .........................................................................................................................................54
18 ADDITIONAL INFORMATION.............................................................................................................................55
18.1 TECHNICAL SPECIFICATIONS........................................................................................................................................55
18.2 RECHARGEABLE BATTERIES SPECIFICATIONS ...................................................................................................................55
18.3 WI-FI MODULES /BLUETOOTH ADAPTERS .................................................................................................................... 56
18.4 OTHER SPECIFICATIONS .............................................................................................................................................56
18.5 DEVICE WARRANTY ..................................................................................................................................................56
INFORMATION FOR ASSISTANCE ...............................................................................................................................57
NOTE FOR SERVICE PERSONNEL ONLY ................................................................................................................ 57
REMOTE CONTROL ...................................................................................................................................................57
TELEMETRY ...............................................................................................................................................................57
APPENDIX A –DATA MANAGEMENT DISCLAIMER .....................................................................................................58
APPENDIX B –EMR INPUT AND OUTPUT FILES SPECIFICATIONS ................................................................................60

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1Manufacturer identification
Manufacturer
Adaptica S.r.l.
Address
Via San Marco, 9/H
35129 Padova (PD) Italy
Telephone
[phone]
Mail
[e-mail]
Web
www.adaptica.com
2Legend of symbols
Manufacturer identification data
Date of manufacturing
Electrical / electronic device subject to the WEEE Directive
on waste disposal
CE mark: this device complies the base requirements of the
Medical Device Directive 93/42/CEE
Direct current (DC)
Warning: necessary information for safety
Important information
Read user manual before use
Indoor use only
Polarity of the power supply plug
Applied part –comes into contact with the patient

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3Intended use of the device
Instrument for the measurement of binocular and monocular refraction based on infrared (IR)
photorefraction.
4Classification and Applied Standards
Classification according MDD 93/42/EEC, Annex IX,
and MDR 2017/745 EU, Annex VIII
Class IIa.
Classification and type of applied parts
Class I, Type B.
IP classification
IPX0 (degree of protection provided by the external plastic shells with reference to the penetration of any
special material or water).
Electromagnetic compatibility
This device has been classified as class B according to the standard IEC 60601-1-2.
Applied standards
EN 60601-1; EN 60601-1-2; EN ISO 15004.

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5Precautions
Electromagnetic compatibility
This device has been tested and found to comply to the limits for medical devices contained in
IEC60601-1-2 and in Medical Device Directive 93/42/EEC. These limits are intended to provide
reasonable protection against harmful interference in a typical medical installation. This instrument
generates, uses and can radiate radio frequency energies and, if not installed and used in accordance with
these instructions, may cause harmful interference to other devices in the vicinity. However, there is no
guarantee that interference will not occur in a particular installation. If the system does cause harmful
interference to other devices, which can be determined by turning the system off and on, try to eliminate
the interference by adopting one or more of the following measures:
•reorient and/or relocate the receiving device;
•increase the distance between the devices;
•In case of charging of the device, connect the system to an outlet on a different circuit than that to
which the other devices are connected;
•consult the manufacturer or field service technician for help.
This equipment has been verified to comply with the limits for a class B computing device, pursuant
to FCC Rules. In order to maintain compliance with FCCregulations, shielded cables must be used with
this equipment. Operation with non-approved equipment or unshielded cables is likely to result in
interference to radio and TV reception. The user is cautioned that changes and modifications made to the
equipment without the approval of manufacturer could void the user’s authority to operate this
equipment.
Portable and mobile RF communications equipment, such as cell phones, can affect medical electrical
equipment: any RF communications equipment shall be used no closer than 30 cm (12 inches) to any
part of the 2WIN-S, including its cables.
The area where the device is to be installed has to comply to the IEC/ISO standards related to the
medical use of an area.
The device must NOT be used in oxygen rich environments or in presence of flammable products.
The device must not be installed in a room exposed to chemical-physical aggressive agents (such as
sulphides, salt, dust, etc.), nor exposed to direct sunlight or lack of ventilation, high humidity, sudden
surges or drops in temperature. The safety and efficiency of the instrument are not guaranteed under these
conditions.
This device is designed to be used indoor. Do not expose the device to water: this could lead to fire or
electric shock.
This device is not to be used during a flight.
Light radiation
The light emitted from this instrument is potentially hazardous. The longer the duration of exposure,
the greater the risk of ocular damage. Exposure to light from this instrument when operated at
maximum intensity will exceed the safety guideline after 30 minutes.

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Precautions and general warnings
The clinical interpretation of the data provided by the device is restricted to licensed eye-care
practitioners.
The process of making a diagnosis using the device results is the responsibility of the eye-care practitioner.
A device specific training is required for any operator to become able to use the system.
For the correct use of the device, it is mandatory to carefully read the instructions in Chapter 0 - Operative
information.
The patient applied part, i.e., the face cushion, shall be disinfected before each patient change, to
avoid patient contamination by infectious agents. Please follow instructions provided on Chapter 4 –
Disinfection of present manual.
Do not open the device: this could lead to electric shocks or damage to the system. No modification
of this equipment is allowed. Do not use the instrument if the cover or other parts of the device have
been removed.
Only technicians authorized by the Manufacturer may service the device. The Manufacturer cannot be held
responsible for system safety should the device be opened, repairs carried out, third party’s software be
installed, or parts be replaced by unauthorized persons.
Inside the 2WIN SD memory card is stored the patient data. This information can contain personal
information such as name/surname/age. This information management is responsibility of the operator.
Only the power adapter provided by Adaptica with the system can be used to charge the 2WIN-S’
battery pack, for safety reasons.
The battery cells of the 2WIN-S cannot be replaced with equivalent item not provided by Adaptica, for
safety reason (risk of explosion).
The battery cells of 2WIN-S cannot be replaced by the user, only by authorized service personnel.
Do not use different configurations of 2WIN and KALEIDOS to compose the 2WIN-S. The serial
numbers of 2WIN and KALEIDOS are matched to create the 2WIN-S, for manufacturing and warranty
reasons.
The operator is not allowed to perform a DOWNGRADE of the 2WIN-S software. Adaptica is not
responsible for the improper use of the device with a downgraded software version.
Do not place objects on top of the device and do not try to sit onto the device. Be sure that the device
is steady on the floor and not over other objects that can affect its stability.

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6Quick user guide
Important
•Carefully read Chapter 5 – Precautions of the present manual before operating the device.
•The 2WIN-S is a stand-alone binocular vision analyzer. It measures refraction of both eyes at the
same time.
•The 2WIN-S should not be confused with a table-top auto-refractometer (AR). ARs are designed to
measure refractive errors of one eye at time, in an artificial condition of far fixation.
•Please familiarize yourself with the measurement conditions and techniques of the 2WIN-S in order
to exploit its full potential.
6.1 Main Applications
•The 2WIN-S is a stand-alone binocular vision analyzer. It detects a patient’s real-time refraction.
•It is a binocular instrument that measures refraction on the basis of eccentric infrared (IR) photo-
refraction (also photo-retinoscopy). Both eyes are measured at the same time, while fixating at 1
meter.
•It is battery operated, non-invasive, fast, and easy to use.
•It automatically measures binocular refraction, pupil distance, pupil size, direction of gaze, and
fixation abnormalities.
•Binocular refraction of children from 3 years of age to seniors.
•Early detection and documentation of multiple amblyogenic factors.
•Over-refraction of contact lenses.
•OPTIONAL (APP), CR-App: phoria/tropia measurements.
•PLUS package (2WIN-S Plus):
•CR-App: phoria/tropia measurements;
•AI-App: anterior segment screening warning customers of possible pathologies of the
anterior segment;
•Personalized tablet;
•EMR connection.
6.2 Exam conditions
The device should be paired with a tablet through Wi-Fi or Bluetooth connection, depending on the model.

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6.3 Measurement tips
•For sphere and cylinder, measurement precision is ±0.25 D or ±0.50 D depending on the range.
The cylinder axis is calculated between 1° and 180° (step 1°) with precision of ±5°. For high refractive
errors (above +7 D and below -7 D), the 2WIN displays “high M”(myopia) or “high H”(hyperopia) in
the upper part of the display. For higher refractive errors (above +15 D and below -15 D), the 2WIN
still displays “high M”or “high H”: in this case, the 2WIN will not display a numerical result, but it will
write “N.A.”(Not Accessible measurement). For big refractive errors, in the case 2WIN succeeds to
estimate the spherical power only, this estimation will appear in the upper part of the display. This
maximum spherical estimation is between ±15 D. Refer to Section 18.1 for further information.
•Make sure the cylinder notation (minus or plus) is set to your preference.
•Make sure the Reliability Index of the measurement is higher than 6 (max. is 9). In case it’s lower
than 6 a message with a hint will be displayed, for the repetition of the measurement.
•Remember that non-cycloplegic refraction can vary depending on several conditions pertaining to
the binocular visual function; in some specific patients, including accommodating children, the 2WIN-
S measurements may vary.
7Description of the device
7.1 2WIN and 2WIN-S
2WIN-S comprises the 2WIN and the accessory tube KALEIDOS.
A number of additional features of the 2WIN-S could be handled only approaching the 2WIN device.
Please, refer to the 2WIN Operator Manual for these options. This manual could be found in the
MicroSD inside 2WIN as well as downloaded at our website: adaptica.com > Products > 2WIN >
Manuals Download.
7.2 2WIN-S
The measuring principle of the 2WIN-S is based on infrared photorefraction. In this technique, infrared light
is projected through the pupils of the patient onto the retina. Depending on the refractive error, the reflected
light forms a specific crescent-shaped brightness pattern within the pupil. The spherical refraction is
calculated based on this crescent pattern. Cylinder and axis measurements are based on the same kind of
calculation, repeated on four meridians.
The 2WIN-S performs the measurement 1 meter (3 feet 3 inches) away from the patient’s eyes, with
continuous tracking of the corneal reflex, for the analysis of the binocular alignment. The device works as a
portable darkroom and allows a contact-less measurement between the patient and the operator.

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The 2WIN-S accepts a pupil diameter between 4 and 7 mm and it is
compatible with the measure both in mydriasis (dilation of the pupil)
and in miosis (constriction of the pupil). It is possible to measure down
to 3.5 and up to 11 mm, but this depends on several conditions. Outside
the 4-7 mm range the overall precision could decrease. Note that
KALEIDOS tube helps inducing a mild mydriasis.
The 2WIN-S, moreover, is able to detect the refraction only of patients
which eyes permit good Purkinje images. Anomalies in such images, due
for example to eye-surgery interventions or intraocular lenses (IOL), do
not allow an accurate measurement.
The 2WIN-S is portable, battery powered, equipped with a computing
integrated unit and controlled through an Android tablet.
2WIN-S data is saved inside “KALEIDOS App”, used to control the device,
and it can be shared through the sharing services provided by the tablet in use. Moreover, the data is saved
in the MicroSD card of the 2WIN inside 2WIN-S.

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7.3 Package labelling
Label
Detail
Explanation
Manufacturer identification
Data: name and address
Fragile –handle with care
This side up –do not reverse
Keep dry
Storage minimum and maximum
temperature
Lithium ion batteries contained or packed with device
Call [phone] for more information
[phone]

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7.4 2WIN-S labeling
Label
Detail
Explanation
Manufacturer identification
data: name and address
model: 2WIN-S
Model name
Connector polarity
18V 2.5A
Input C.C. voltage and current
CE mark and Notified Body
identification code
Electrical / electronic device
subject to the WEEE Directive
on waste disposal
Read manual strictly before
operation
Turn on device
1
Button 1 (see Section 9.1)
2
Button 2 (see Section 9.1)
Battery fully charged
Battery discharged
Serial number
IP00
Not protected against ingress of
objects and water
Year of production
Applied part type B

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BACK INDOOR
CONTROL PANEL
UPPER SIDE

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7.5 Interfaces
2WIN-S
The customer can operate the 2WIN-S from the control panel depicted
in figure. The buttons’ role is described in the following, and also in
Section 9.1.
A: BUTTON 1 - "Measurement”
Press for 2 sec to start a new measurement
B: BUTTON 2 - “Connection”
-Press for 2 sec to reset Wi-Fi and Bluetooth connection
-Press for 4 sec to prepare the system to be paired with 2WIN App: this is a deprecated legacy feature.
C: POWER BUTTON
-Short press to switch the system on
-Press for 2 sec to switch the system off
-Long press the button to force the power off
D: BATTERY LEVEL BUTTON
Short press to see the 2WIN-S battery level
2WIN
Inside the USB & SD connection door there are a Micro-USB port, which connect the 2WIN camera to the
KALEIDOS tube, and a MicroSD card holder.
For a summary of the functions of the buttons, refer to the following, and also to 2WIN Operator Manual.
Please, note that operator can have access to 2WIN menu if, and only if, the KALEIDOS App is not
connected to the 2WIN-S device.
A
B
C
D

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MAIN FUNCTION
Short press
Long press
BUTTON A
Switch-on;
Open Applications Menu
Switch-off
BUTTON B
Zoom after exam
Print and Save
JOYSTICK
Navigate in the menu
CENTER: contextual help
BUTTON C
Toggle eye
Notification center
BUTTON D
Start a new exam *
*: This function is operating only if the “KALEIDOS mode” is switched on (default in 2WIN-S
configuration); otherwise, the functionality of BUTTON D will be different. Refer to Section 7.4 and
9.7 of 2WIN Operator Manual for further information.
The JOYSTICK features contextual functions:
•push CENTER to enter menu or to say OK
•the other four direction allow operator to navigate in the menu
Please, refer to the 2WIN Operator manual for further information.
8Operative information
8.1 Operating conditions
The device needs to be operated under the following environmental conditions:
•Temperature: 10 to 40 °C (50 to 104 °F)
•Humidity (max): 90% not condensing

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8.2 Unpacking
The box contains (default configuration):
•the 2WIN-S device, divided in:
▪Top (Part A)
▪Middle (Part B)
▪Bottom (Part C)
▪Base-support, cradle (Part D)
•the 2WIN-S battery charger
•EU/US AC wall adapter
•2WIN accessories (refer to 2WIN Operator Manual):
▪a MicroSD memory card (containing the electronic version of the Operator Manuals)
▪a USB cable (Micro-USB to USB-A)
▪an external battery charger (not in Plus configuration)
▪two rechargeable batteries (not in Plus configuration)
▪an occluder (infrared patient’s eye occlusion system)
The MicroSD memory card, besides containing the electronic version of the manuals, it contains also
presentations and further instructions on how to operate the device.
For further information regarding 2WIN and its Applications, please refer to video tutorials that can
be found in the Adaptica’s YouTube channel: https://www.youtube.com/user/AdapticaSrl.
8.3 Access to 2WIN
To have access to the 2WIN device, the rear hinged lid of the KALEIDOS tube has to be opened.
Removing the MicroSD memory card
First remove the USB cable from the 2WIN device, and then remove the MicroSD card from the device
Navigating in the 2WIN menu
Please, note that operator can have access to 2WIN menu if, and only if, the KALEIDOS App is not
connected to the 2WIN-S device. Refer to Chapter 12 – Remote control: KALEIDOS App of the manual.
The Menu is activated by pressing the center of the JOYSTICK. To exit the Menu, push left on the main Menu
page, or by pressing the BUTTON A.
A
B
C
D

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To navigate in the Menu, use the four directions of the JOYSTICK: up and down will move up and down the
highlighted choice, right will select the highlighted choice navigating deeper by one level in the menu, left
will step back to the previous menu level.
For further details, please refer to 2WIN Operator manual > Section 9.7 - Menu
8.4 Before operation
After completely charging the device, be sure to set up date and time. Current date and time will be also used
into the measurement exam’s report.
The 2WIN device has an automatic hardware self-test procedure that can be activated as an option from the
2WIN inside KALEIDOS, as follows: Menu > Functions > Aux > Auto test. This procedure may be executed any
time to verify hardware integrity.
8.5 Data management disclaimer
When turned on the first time, 2WIN-S present a disclaimer related to the management of data telemetry of
the instrument. The operator is asked to read the document and accept the terms, if not 2WIN-S will work
but some functionalities will be disabled (Telemetry and Remote access). You can read the document at the
end of this manual (Appendix A) for all the details.
8.6 Important notes on Battery
The device must be charged at least once every 30 days.
When using 2WIN-S, the 2WIN is connected to the KALEIDOS battery pack through the USB cable:
2WIN’s internal battery must be removed, whether the battery was inserted for using the 2WIN
separately.
Detaching the USB cable, the 2WIN will switch off in 3 seconds.
9Operative instructions
To power on the 2WIN-S, push the ON/OFF BUTTON on the Control Panel of the KALEIDOS (refer to Section
7.5).
To turn OFF the device, long press the ON/OFF BUTTON. Alternatively, you can turn off the device from the
KALEIDOS App as follows: Settings > General > System > Shut Down.
2WIN-S has no auto-shutdown timer.

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To operate correctly the instrument, it’s important to carry out the following main steps:
1. Device setup
2. Preparation of the patient
3. Measurement
9.1 Device setup
To charge the system:
1. Connect the provided power supply cable to the INPUT 18V –25A,
depicted in figure.
2. Connect the other end of the power supply to the line.
3. In order to monitor the battery charge level, press the battery charge
button.
Configuration steps
Refer to Chapter 11 of this Operator Manual for 2WIN-S configuration using the Wi-Fi tablet application
(deprecated legacy feature).
The 2WIN-S configuration using the Bluetooth tablet application (KALEIDOS App) is briefly described in the
following.
At first use, it is necessary to pair the 2WIN-S to the tablet, following these instructions:
•Install the KALEIDOS App on your tablet
•Check that Bluetooth is enabled on the tablet
•Switch the 2WIN-S on
•Run KALEIDOS App on tablet
•Tap on the Bluetooth icon on the KALEIDOS App to start available Bluetooth devices search. A window
showing all the available 2WIN-S will appear.
•Connect to the desired 2WIN-S. When the pairing is complete a confirmation message will appear.
Refer to Chapter 12 for further information.
In the 2WIN-S Plus configuration, the provided tablet is already paired with the device.
For the 2WIN-S configuration and how to assembly the instrument, refer to the 2WIN-S Quick Start
Guide provided with the system.

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Patient age
2WIN-S uses the patient’s birthdate / age range as a corrective parameter to determine the refraction. This
information is used in particular to compensate accommodation in young patients with hyperopia-based
refraction error. Take care of selecting the right birthdate / age range before taking the measurement. Take
into consideration that the default age range is 0-2 years.
Control Panel functionalities
Button
Power
1 – Measure
2 – Connection
State
Flashing Green
The system is booting
up
Exam ongoing
-
Fixed Green
The system has
successfully started.
There is a blinking
when the activity is
normal
Measure well done
2WIN-S correctly
connected to the
application
Fixed Red
Error: please shut down
the system and power it
on again
Measure error:
repeat the
measurement
2WIN-S not
connected: check
connections’ settings
Flashing
Yellow
The system is shutting
down
-
Connection ongoing
(Wi-Fi/BT)
Fixed Yellow
Firmware updating
-
2WIN-S not
connected to the
application
Flashing blue
Pairing ongoing with
application
Button
Power
1 – Measure
2 – Connection
Function
Short press
System power up
-
-
Long press
2 sec: system shut
down
More: force power off
2 sec: start/stop a
measurement; the
exam is
automatically saved
2 sec, until flashing
yellow: WiFi\BT
connection reset
4 sec, until flashing
blue: start application
pairing
9.2 Preparation of the patient
The operator shall instruct the patient to look inside the tube and to try to open wide his eyes so to avoid
eyelashes covering the pupils.
The operator shall instruct the patient to look, during the measurement, at the fixation target positioned at
the bottom of the device: three white dots in the shape of a triangle. Most importantly, the patient must not
follow with his eyes the moving red lights that turn on during the exam but concentrate on the fixation target.
In case of monocular measurement, ask the patient to cover his/her other eye with the provided occluder.