Supplementary Online Content

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1 Supplementary Online Content Bastawrous A, Rono HK, Livingstone IAT, et al. Development and validation of a smartphone-based visual acuity test (Peek Acuity) for clinical practice and community-based fieldwork. JAMA Ophthalmol. Published online May, 01. doi: /jamaophthalmol eappendix. Visual Acuity Test Methods etable 1. LogMAR Equivalents for the Snellen Test [1] and WHO Visual Categories Used in This Study etable. Results of the Pairwise Comparisons of the Right and Left Eye Showing Bland-Altman and Pearson Correlation Analysis etable. Comparison of ETDRS (Reference) by an Ophthalmic Clinical Officer and Peek Acuity by a Community Health Care Worker for Detecting Severe Visual Impairment or Blindness etable 4. Comparison of ETDRS (Reference) by an Ophthalmic Clinical Officer and Peek Acuity by a Community Health Care Worker for Detecting Severe Visual Impairment or Blindness efigure 1. Demonstrating the Peek Vision SightSim Application efigure. Vision Testing at Home With Snellen efigure. Vision Testing in the Clinic With ETDRS LogMAR efigure 4. Vision Testing in the Clinic With Peek (Comparison With ETDRS Chart) This supplementary material has been provided by the authors to give readers additional information about their work.

2 eappendix. Visual Acuity Test Methods (1) Snellen Acuity (in patient s home and in the clinic): 1. The test was explained to the participant. Testing took place in the following location (in order of preference): inside, outside in the shade, outside.. Three meters was measured from the participant to the Snellen chart using a precut length of string 4. Presenting vision was tested.. One eye was tested at a time, right eye then left eye. The eye not being tested was covered by the patient's palm and checked by the tester to ensure it provided sufficient occlusion. 6. The tester sequentially points, using a black pointer, at all the optotypes (E's) from largest (Snellen 6/60) to smallest (Snellen 6/) with the tester determining a correctly seen optotype when the participant points in the direction the arms of the E points and an incorrect result when the participant either points in the wrong direction or indicates that they can not see the optotype. 7. The test terminated (for each eye) when less than half of the optotypes of a particular line were correctly determined. The result was recorded as the letter size for that line.. The same sequence is repeated for the left eye. 9. If a participant could not see the largest optotype at three meters. The testing distance was halved to 1.meters. If the largest optotype was not correctly identified at 1.m, the tester asked the participant to identify the number of fingers being held up at 0 centimeters (against a white tshirt as background). If Counting Fingers is failed, the tester asked the participant to identify hand movements in front of the eye being tested. If Hand Movements is failed, a torch is used to determine if the participant had either Perception of Light or

3 No Perception of Light 10. The testing time is measured from the displaying of the first optotype to the right eye to the recording of the final result for both eyes. 11. Ambient light for the test was measured using a calibrated Luxmeter (ILM1A light meter, ISOTECH). () Peek Acuity (in patient s home and in the clinic): 1. The test was explained to the participant.. Two meters was measured from the participant to the smartphone using a precut length of string. Presenting vision was tested. 4. One eye was tested at a time, right eye then left eye. The eye not being tested was covered by the patient's palm and checked by the tester to ensure it provided sufficient occlusion. The tester displays the smartphone screen to the participant, but does not observe the screen themselves. The smart phone displays a single optotype (E in one of 4 orientations: 90, 10, 70, 60) in a bounding box. The participant points in the direction the arms of the E points (see figure 7) and the tester swipes the surface of the smartphone screen in the direction indicated (whether correct or incorrect). If the participant indicates they cannot see the optotype the phone was shaken (shake gesture detected by device accelerometer, and records not seen ) 6. The test algorithm concludes (for each eye) automatically and the result is stored on the device and displayed on screen. 7. The same sequence is repeated for the left eye.. If a participant cannot see the largest optotype at two meters, the software app instructs the tester to move to a testing distance of one meter. If the largest optotype is not correctly identified at one meter, the app instructs the tester to display the screen at 0 centimeters and asks the participant to identify the

4 number of black bars being presented (one to four). If Counting Bars is failed, the app instructs the tester to hold the screen in front of the eye being tested. A black box, half the width of the screen moves gradually horizontally backwards and forwards across the screen repeatedly. If Hand Movements is failed, the flash light on the smartphone comes on and the tester is instructed to determine if the participant has either Perception of Light or No Perception of Light 9. The testing time is measured from the displaying of the first optotype to the right eye to the automatic recording of the result for both eyes. 10. Ambient light for the test is measured using the phones in built light sensor, as well as a calibrated Luxmeter for comparison (ILM1A light meter, ISOTECH). () LogMAR Visual Acuity (in the clinic only): 1. The test was explained to the participant. Four meters was measured from the participant to the ETDRS chart using a tape measure.. Presenting vision was tested. 4. One eye was tested at a time, right eye then left eye. The eye not being tested was covered by an occluder and checked by the tester to ensure it provided sufficient occlusion.. The tester sequentially pointed, using a pointer, at all the optotypes (E's) with the tester determining a correct result when the participant points in the direction the arms of the E points and an incorrect result when the participant either points in the wrong direction or indicates that they can not see the optotype. 6. The test terminates (for each eye) when no further optotypes are correctly determined. The result was recorded as the number of optotypes correctly identified. 7. The same sequence was repeated for the left eye.. If a participant could not see the largest optotype at four meters. The testing

5 distance was reduced to one meter. If the largest optotype is not correctly identified at one meter, the tester the tester asked the participant to identify the number of fingers being held up at 0 centimeters (against a white tshirt as background). If Counting Fingers is failed, the tester asked the participant to identify hand movements in front of the eye being tested. If Hand Movements is failed, a torch is used to determine if the participant had either Perception of Light or No Perception of Light 9. Ambient light for the test was measured using a calibrated Luxmeter (model) and was performed within a range of 0 to 00 lux (ISOTECH: ILM1A light meter) in accordance with British Standards for acuity assessment.

6 etable 1. LogMAR Equivalents for the Snellen Test [1] and WHO Visual Categories Used in This Study Snellen LogMAR Visual Category NPL 4.0 PL.0 Blindness HM. CF 1. 6/10 1. Severe Visual Impairment 6/ /6 0. Moderate Visual Impairment 6/ /1 0. Mild Visual Impairment 6/1 0. 6/9 0. Normal 6/6 6/ 0.1 LogMAR: Logarithm of the Minimal Angle of Resolution NPL: No perception of light, PL: Perception of light, HM: Hand Movements, CF: Counts Fingers

7 etable. Results of the Pairwise Comparisons of the Right and Left Eye Showing BlandAltman and Pearson Correlation Analysis Compari son Ey e 1 R 7 1 L 7 R 7 L 7 R 7 L 7 4 R 4 L R L 6 R 6 L 7 R 7 L R L N Description Diff ence of rage ETDRS vs. Snellen in Clinic ETDRS vs. Snellen in 0.1 Clinic 0 ETDRS vs. Peek in Clinic 11 ETDRS vs. Peek in Clinic Snellen Clinic vs. Peek Clinic 07 Snellen Clinic vs. Peek Clinic Peek Home vs. Snellen Home Peek Home vs. Snellen Home ETDRS vs. Snellen at home ETDRS vs. Snellen at home Snellen Clinic vs. Snellen Home Snellen Clinic vs. Snellen Home Peek Home vs. Peek Clinic Peek Home vs. Peek Clinic ETDRS vs. Peek at Home ETDRS vs. Peek at Home % Confidence Interval Mean Difference Low Upp er er % Limits of Agreement Low er Upp er Pearson correlation coefficient (9%CI) 0.9 ( ) 0.90 ( ) 0.96 ( ) ( ) 0.90 ( ) 0.99 ( ) 0.90 ( ) 0.7 ( ) 0.6 ( ) 0.6 ( ) ( ) 0.91 ( ) 0.9 ( ) 0.90 ( ) ( ) ( )

8 etable. Comparison of ETDRS (Reference) by an Ophthalmic Clinical Officer and Peek Acuity by a Community Health Care Worker for Detecting Severe Visual Impairment or Blindness Reference ETDRS Severe VI or Blind Yes No Peek Yes 11 No 1 Sensitivity = 4.6% (9% CI: %) Specificity = 97.7% (9% CI: %) PPV = 6.% (9%CI: %) NPV = 99.1% (9%CI: %) PPV: Positive predictive value, NPV: Negative predictive value

9 etable 4. Comparison of ETDRS (Reference) by an Ophthalmic Clinical Officer and Peek Acuity by a Community Health Care Worker for Detecting Severe Visual Impairment or Blindness Reference ETDRS Severe VI or Blind Yes No Peek Yes 11 No 1 Sensitivity = 4.6% (9% CI: %) Specificity = 97.7% (9% CI: %) PPV = 6.% (9%CI: %) NPV = 99.1% (9%CI: %) PPV: Positive predictive value, NPV: Negative predictive value

10 efigure 1. Demonstrating the Peek Vision SightSim Application

11 efigure. Vision Testing at Home With Snellen

12 efigure. Vision Testing in the Clinic With ETDRS LogMAR

13 efigure 4. Vision Testing in the Clinic With Peek (Comparison With ETDRS chart)