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  5. FP1407 : Mission Impossible Made Possible by A Portable Vision Screener

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Dr. Veena Kannvsamy, K10574

AIM: To assess the effectiveness of Portable vision screener (Plus optix S12c) in screening for Amblyogenic factors in children under6 years by non-ophthalmic persons.

BACKGROUND: Amblyopia is a condition with unilateral or bilateral subnormal vision (at least 2 lines less than normal or 2 lines less than the fellow eye in unilateral cases) without any local ophthalmic abnormality and which is reversible if treated appropriately at proper time. The critical period for amblyopia treatment was demonstrated for children younger than seven years old4. It is important to consider screening for amblyopia considering the critical age and inability to appreciate amblyopia either by parents or children at this age.

Photoscreening offers an alternative to traditional vision screening by retinoscopy, proving earlier detection of potential visual problems. In a developing country like India, where there is no mandatory and regular school eye screening, screening tools can be a big boon. Photorefractors were made to rule out amblyogenic ametropias in children18,19. Many photorefractors have been developed recently like Plusoptix, SPOT, TWIN etc. S-12C is the first handheld model with added advantage of easy carriage, handling,functions with rechargeable batteries and light weight.

Although studies have been done previously using Plusoptix photoscreener old models like S-04, S-09 which needed to be connected to desktop  and constant supply of electricity was needed for there working, this hampered large scale use in rural areas. No study using Plusoptix S-12C model has been done till date in South Indian population. We have included children less than 3 years of age, the pre-verbal children in our study considering paucity of information related to screening children in this age group.

PLUSOPTIX

Plusoptix is a digital photoscreener that takes digital video of the patient’s eye using infrared beams that are immediately analysed by the software installed on the linked laptop. This instrument is remarkable as it is easy to use in assessing young children and requires less training. Risk factors for amblyopia can be detected in a matter of seconds with high accuracy during vision screening using Plusoptix Photoscreener. Previous studies have shown promising results of Plusoptix in detecting amblyopia risk factors.

Screening results with photoscreener measures: Refraction values including myopia, hyperopia, anisometropia and astigmatism. It also takes into account pupil size (anisocoria), corneal reflex (symmetric/asymmetric eye alignment).

During a measurement, device records a series of images. To attract attention of child during the measurement, the device plays a “warble” sound. The speaker required for this is located behind the vertical slits on front side of the camera. The camera lens and LEDs required for illuminating the images are located behind the black protective shield with the stylized face. This face is used as a fixation aid.

Figure 7: Plusoptix S-12C

The device needs to be placed at distance of one meter (3.3 feet) and camera aligned so that both eyes can be seen on the screen. Then slowly move towards patient until camera picture on screen is in clear focus. Pupils are framed with white boxes, then by red circles and finally by green circles. Stop moving once a green line is plotted in between both pupils and a second “warble” sound heard.  The measurement starts at this point automatically. A “ping” sound signals that the measurement is complete. The measurements can be saved or printed, before we perform the next measurement.

The device is equipped with a WLAN interface. This WLAN interface can be used to connect to a DHCP server.

The device uses infrared light to perform measurements. The same infrared light is part of sunlight and emitted by all incandescent light sources such as light bulbs and halogen spots. This infrared light is invisible to human eye and non-hazardous. To obtain accurate measurements it is important to avoid interfering infrared ambient light by using curtains, blinds or shutters.

Steps for recording the data include: setting date and time, choosing an age group; necessary to compare measurement results to the age specific referral criteria, entering patient data (either name, date of birth or an ID number; examination location and contact information can also be saved),  recording the data.

PLUSOPTIX 12

Special features of Plusoptix S-12 are that it is handheld and portable camera model (compared to S-09 model with cable to computer, separate monitor and printer/labels). Misalignment of eyes is displayed on device as series of red dots which were noted manually in older versions.72The latest version encompasses a ‘symmetry of corneal reflex’ assessment as part of refer/pass criteria.73

Features of Plusoptix are: Proven accuracy, both eyes are screened simultaneously, “pass” or “refer” result is displayed automatically and screening one child takes around 0.8 seconds only. Automated vision screening is now recommended for children of preschool age by American Academy of Ophthalmology.71

PLUSOPTIX S 12C

Plusoptix S12C has a 5.7 inch screen with capacitive touch sensor located on the rear side of the device. To activate one of the functions displayed on the screen, gentle touch is needed. Two orange buttons are on/off button, and the shutter. The device has three interfaces – USB, Mini-USB and SD card. On pressing the ON button, screen switches on immediately and the device is booted. The device is ready for use after approximately 25 seconds.

Mobile vision screener “Plusoptix S12C” measures both eyes simultaneously (binocular) in 0.5 seconds at a distance of one meter (3.3 feet). Therefore even small children with a short attention span can be measured starting at the age of 6 months.74 The simultaneous measurement of both eyes also enables a reliable comparison of the measurement values of both eyes.   

Plusoptix S12C model can be connected to EMR (Electronic Medical Records) that enables electronic importing of patient data and exporting of measurement values. Data can be transferred from EMR system in form of a simple CSV file or GDT format, in this latest model. Patient data can be imported from a CSV cable via the USB port and exported from backup copies and reports that can be created and saved in an internal database.

There are five validated sets of referral criteria to choose from. These five sets are called ROC 1, ROC 2, ROC 3, ROC 4 and ROC 5. Each of these sets defines age-specific threshold values which lead to a “Refer” screening result. We used ROC1 for our study.

Details of the age specific referral criteria as per the ROC 1 is as shown in table below:

METHODOLOGY

  • 6 months to 6 years children enrolled under ICDS and schools were included in the study and children who are  not co-operating or  parents not willing for their child’s participation in the study, Children with other ocular conditions like Conjunctivitis or Trauma, Children with any systemic illness were excluded

Concerned authorities at schools, Anganwadis and Pre schools were preinformed and explained about screening with Plus optix and  consent forms distributed 3 or 4 days prior; making sure that consent forms were signed by parents/ legal guardian.

SCREENING WITH PLUSOTIX

Field workers were trained to screen children with Plusoptix photoscreener. They entered and saved the information regarding the students name, fathers’ name, and gender in the machine. Age criteria was selected as per the child’s date of birth. The Referral criteria chosen was ROC 1 (Receiver Operating Characteristics) for screening all children in our study.

On starting the plusoptix machine, a warble sound attracts the attention of the child and the camera captures both eyes within few seconds in the white rectangle on screen and a measurement is performed automatically. Screening distance is 3.3 feet (1 meter) with a tolerance of +/- 2 inches (+/- 5 centimeters). The level of eyes of child should be at the same level as Plusoptix screener. Dim illumination is needed for optimal screening.

Plusoptix then gives results as Pass/ Refer/ Inconclusive.

Pass – Child is normal.

Inconclusive – Machine is not able to assess.

Refer –Child needs further evaluation by ophthalmologist.

Children who fall in Refer and Inconclusive were referred to Base Hospital for further evaluation

Results

After training the technicians in using the vision screener, 100000 children were screened at ICDS centres preschools in 3 Districts. Children with refer or inconclusive results were referred to base hospital for further evaluation.

Result: Out of 102,402 children screened, 79,712 passed 22690 children referred to the base hospital. 3,781 children seen at base hospital and 2336 children were at referral camps. Total of 1,789 children received glasses&48children (62 eyes) underwent surgeries for Cataract, Squint and Ptosis etc.

STRENGTHS:

  • To the best of our knowledge this is the first study using Plusoptix S12-C model in Indian population.

We have included younger age group (less than 3 years) children, which have been included in very few studies done earlier; considering chances of poor co-operation.

RECOMMENDATIONS:

1) We recommend use of Plusoptix S12-C as a tool for mass screening

2) It can have a huge impact on Screening cost involved in such screening programmes

3) This can help in covering large population and can reduce loads of Amblyopia, by helping provide treatment at correct age

4) Handheld easy usable portable modelallows any non-professional person to do the screening.

5) This can be used for screening children at a younger age also. As our study did not show significant difference between sensitivities in 2 groups.

Conclusion: In spite of the referral rate (22.15%) being high, the number children benefitted by the screening shows it is a very useful tool. Modifying the referral criteria for Indian standards and combining with traditional model will make the screening more efficacious in mass screening of children less than 6 yrs

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  78. Article I. Bloomberg JD,  SuhDW. The accuracy of the plusoptiX A08 photoscreener in detecting risk factors for amblyopia in central Iowa. J AAPOS. 2013 Jun;17(3):301-4.
  79. Article II. Peterseim MM et al. Combining automated vision screening with on-site examinations in 23 schools: ReFocus on Children Program 2012 to 2013.J Pediatr Ophthalmol Strabismus. 2015 Jan-Feb;52(1):20-4

 

 

 

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