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ORIGINAL ARTICLE
Year : 2022  |  Volume : 66  |  Issue : 2  |  Page : 171-175  

Cost-Effectiveness of photoscreeners in screening at-risk amblyopia in Indian children


1 Director, Medical Administration, Sankara Eye Hospitals, Bengaluru, India
2 Consultant, Department of Pediatric Ophthalmology, Sankara Eye Hospitals, Bengaluru, India
3 DNB, Sankara Eye Hospitals, Bengaluru, India

Date of Submission27-Sep-2021
Date of Decision02-Feb-2022
Date of Acceptance11-Feb-2022
Date of Web Publication12-Jul-2022

Correspondence Address:
C Vidhya
D201, Pavani Sreshta Apartments, Munnekolala, Marathahalli, Bengaluru, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijph.ijph_1848_21

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   Abstract 


Objectives: Amblyopia is the most common cause of preventable vision impairment in children. This study tried to evaluate the cost-effectiveness of photoscreeners in identifying refractive errors making children at risk of amblyopia. Materials and Methods: This was designed as a prospective, open-label, randomized controlled study to compare the cost-effectiveness of photoscreeners (2WIN Adaptica and Plusoptix) versus autorefractor and Mohindra retinoscopy to identify the at-risk amblyopia. This study was conducted from October 2018 to December 2018 in coordination with Nanna Kannu school screening project and children in the age group of 5–11 years were included in the study. The photoscreening was done by lay screeners. A supervising ophthalmologist collated all data. Cost-effectiveness was calculated for the individual instruments and compared. The average time is taken for each instrument to record the refractive error was calculated and compared with the Mohindra retinoscopy. Results: Number of children included in this study was 2910. The mean age of the children was 7.82 + 0.65 years. The mean time taken for 2WIN Adaptica was 6 sec, Topcon –10 s, and Plusoptix –4 s. Plusoptix showed the minimal time for screening a child when compared to all other methods. The Plusoptix and 2WIN Adaptica were shown to be cost-effective when compared to Mohindra retinoscopy (P < 0.05). Conclusion: Photoscreening using Plusoptix and 2WIN Adaptica with lay screeners was < seven times the cost incurred and five times faster than the trained optometrists using either autorefractor or Mohindra retinoscopy and thus more cost-effective in screening a large number of young children with at-risk amblyopia at the community level.

Keywords: At-risk amblyopia, cost-effectiveness, layscreeners, photoscreeners, plusoptix


How to cite this article:
Murali K, Vidhya C, Murthy SR, Mallapa S. Cost-Effectiveness of photoscreeners in screening at-risk amblyopia in Indian children. Indian J Public Health 2022;66:171-5

How to cite this URL:
Murali K, Vidhya C, Murthy SR, Mallapa S. Cost-Effectiveness of photoscreeners in screening at-risk amblyopia in Indian children. Indian J Public Health [serial online] 2022 [cited 2022 Aug 13];66:171-5. Available from: https://www.ijph.in/text.asp?2022/66/2/171/350666




   Introduction Top


Blindness estimates across the world in 2020 showed that 1.1 billion had some form of vision impairment that needs to be addressed.[1]

Amblyopia is the most common cause of preventable vision impairment in children with a prevalence of 0.8% to 1.75% in India as per various studies.[2],[3],[4] Amblyopia caused by refractive errors can be treated successfully within the critical developmental period by prescribing glasses and/or occlusion therapy of the nonamblyopic eye. If left untreated, they will have permanent visual impairment for the entire life. American Association for Pediatric Ophthalmology and Strabismus (AAPOS) have issued the referral criteria for screening at-risk amblyopia and hence detecting them in the early window period.[5]

Screening for amblyopia by specially trained staff would be effective but comes at a cost. Konig et al. and Schnorbus et al. showed the cost of preschool screening by orthoptists to be 13–51 euros/child.[6],[7] Although the human power costs in India remain lesser, the sheer volume considering children population of 15, 87, 89, 287 (Census 2011), it is challenging to make early detection more accessible by reducing the cost and human power, while maintaining or improving detection quality.

Screening for refractive risk factors can be done using traditional methods based on subjective visual acuity which would require highly skilled persons, longer testing time, and longer attention span of the children, to the methods not requiring child's participation like automated refraction and photoscreening. It is important for the policymakers, physicians, and eye care providers to understand the complexities of predictive value of screening and then evaluate the type of technology that might be suitable to screen the children in the community effectively. Cost-effectiveness would be a major factor for consideration here.

Agarwal et al. proved that refractive errors can be accurately measured using relatively inexpensive and portable handheld field devices in a hospital setting.[8]

The WHO's world report on vision recognized the need to advance eye health as an integral part of universal health coverage and also acknowledged that quality of care and cost of priority eye care could determine the choices that countries make.[9]

The aim of this prospective study was to compare the cost-effectiveness of photoscreeners with the tabletop autorefractor and gold standard of Mohindra refraction in a school eye health screening setting in identifying refractive errors increasing at-risk amblyopia in these children. We hypothesize that photoscreeners are cost-effective in identifying refractive errors in these children.


   Materials and Methods Top


The study was designed as a prospective, open-label, randomized controlled study after the approval from our institutional scientific and ethical committee. The study was designed to compare the cost-effectiveness of photoscreeners (2Win Adaptica, Plusoptix A12C (software version 5.0.11.0) Plusoptix A12C (Nuremberg, Germany) versus Topcon Autorefractor RM-8900B (Topcon, Germany) and Mohindra retinoscopy to identify the at-risk amblyopia. The 2003 AAPOS referral criteria[7] are:

Anisometropia (spherical or cylindrical) >1.5D.

  • Hyperopia >3.5D in any meridian
  • Myopia >3.0D in any meridian
  • Astigmatism >1.5D at 9° or 18°; >1.0D in oblique axis (more than 10° from 90° or 180°)
  • Any manifest strabismus
  • Any media opacity >1 mm in size
  • Ptosis ≤1-mm margin reflex distance.


The children in the age group of 5–11 years were included in the study [Table 1] (after obtaining consent from the parents), and the study was conducted from October 2018 to December 2018 in coordination with Nanna Kannu school screening project. Nanna Kannu is a comprehensive eye care program for children, conducted in association with the Government of Karnataka, India. The project uses a three-tiered model with:
Table 1: The inclusion and the exclusion criteria

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  • Teacher volunteer as primary vision screeners
  • Secondary screening at school with refraction and glass prescription
  • Tertiary screening at the base hospital for diagnostics and surgical care, as referred from secondary screening.


Inclusion and exclusion criteria are mentioned in the [Table 1].

The study was done for a period of three months, during which the total number of screening camps conducted was 30, and the data were included in the study. The screening was scheduled in government schools, where the cost for renting the facility is zero.

The screening was done as given in the flowchart [Figure 1].
Figure 1: Nanna Kannu screening protocol.

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The photoscreening was done by lay screeners, who were the volunteers trained in the technique of photoscreeners.[6] Lay screeners were trained in the techniques of photoscreeners for 1 week at the base hospital. Simple randomization technique using random number generator was used to allot the lay screeners for the individual camps to avoid the bias in time taken with each of photoscreeners.

A supervising ophthalmologist collated all data, and to avoid bias, lay screeners were interchanged on various days of the screening, and they and the optometrists were masked from the result. All examinations were done on the same screening visit. While the refractive error was noted as spherical and cylindrical power in all subjects, we converted this to the spherical equivalent for analysis.

Cost-effectiveness was calculated for the individual instruments and defined as the total screening and examination costs required per case of amblyopia detected.[10] As per the institution protocol, 5 years is the typical lifespan considered for hardware-based screeners. The costs considered the purchase price, insurance, and annual maintenance costs as relevant for the instruments.

Incremental cost-effectiveness ratio (ICER) is defined by the difference in cost between two possible interventions, divided by the difference in their effect. The ICER represents the additional cost of one unit of outcome gained by one strategy compared with another.[11]

The ICER can be estimated as:



Where C1 and E1 are the cost and effect in the intervention group and where C0 and E0 are the cost and effect in the control care group.

We used four instruments (Topcon autorefractor, 2WIN Adaptica, Plusoptix A12C, and Mohindra retinoscopy) for the screening and the instrument which has the least cost using above formula will be ranked first and other three devices will be compared and analyzed.

The present value of ordinary annuity chart is used to arrive at per child cost of instrument. The WHO recommends 3% discount rate.[10] After getting the lifespan of the instrument which we would use is five years, we divided the cost by 4.57971 to get an annual cost using the present value of ordinary annuity chart.

  1. Wage for the personnel operating the specific instrument per child = wage for lay screener per day (or optometrists) X total days of screening


  2. Total children screened

  3. Average time taken for each instrument to record the refractive error was calculated and compared with the Mohindra retinoscopy.



   Results Top


Number of children included in this study was 2910. The mean age of the children was 7.82 ± 0.65 years (Range-5–11 years).

The wages of lay screeners were 300 INR and technical person 700 INR/day. This was used to calculate the wage for the personnel operating the specific instrument per child.

The mean time taken for 2WIN Adaptica was 6 sec, Topcon was 10 s, and Plusoptix was 4 s [Table 2]. Plusoptix showed the minimal time for screening a child when compared to all other methods. The difference was statistically significant when compared to Mohindra and Topcon (P < 0.05).
Table 2: Time taken for screening a single child using various methods

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The Plusoptix and 2WIN Adaptica were shown to be cost-effective when compared to the gold standard Mohindra retinoscopy (P < 0.05) provided the large number of children were screened during the program [Table 3].
Table 3: Cost-effectiveness of the screening program per child per year

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   Discussion Top


Uncorrected refractive errors were found to be the main reason for visual impairment and amblyopia in children.[12] Community-based eye care in India is limited with the constraints of accessibility, affordability, and accountability.[13]

Screening of young children could definitely reduce the prevalence of amblyopia. Birch et al. and Longmuir et al. have shown that early vision screening programs can achieve high detection and referral rates of amblyopia at relatively low cost.[14],[15]

With a combination of low resources and high disease burden, there is enough evidence of opportunities by technology to not only screen and provide care but also to drive research in child health globally. It is critical to ensure that these solutions are relevant and cost-effective, deploying these in India could allow the learnings to be applied in global health interventions.[16]

Studies by Parinaz et al. and Yan et al. have proved the instrument-based screeners to effectively screen for risk factors of amblyopia.[17],[18] Our prospective study analyzed the cost-effectiveness of photoscreeners comparing with Mohindra retinoscopy in identifying at-risk amblyopia children in school screening program. The efficacy of these photoscreeners in identifying at-risk children with amblyopia in our population has already been published.[19]

The cost-effectiveness of 2WIN Adaptica and Plusoptix in screening programs in our study was 0.33 INR and 0.16 INR/child/year, respectively, very much lower than Mohindra which was 2.24 INR. Catharina et al.[20] showed the amblyopia screening costs using photoscreeners to be €3.73–9.93/child, higher than our cost shown in the study. For photoscreening, our cost estimates are less than that reported in the literature (€5.35–7.20).[17],[21] The difference may be due to the difference in cost of human power in these regions.

The learning curve to use the devices was similar. Catherine et al.[20] showed the time taken for photoscreening per child as 1.1 min (on average) and with conventional vision screening as 3.1 min. In our study, the time taken was much lower than this, with the photoscreening an average of 5 s and with Mohindra technique as 2.5 min. The differences in time estimates might be due to the difference in starting point of measurement of time and the age group of the children. In our study, we started the clock just after explaining the procedure to the child.

Since this study was part of our ongoing Nanna Kannu program, children are counseled in a group on what we intend to do. The consent forms were also shared earlier for the students to share with their parents. Hence, we felt taking the overall time may not be apt.

The lifetime costs of the machines could vary; however, we noted that taking it as per the hospital protocol allowed us to arrive at comparable estimates. We have also seen the technology evolve and taking a longer horizon may impact the efficiency of the screening. We also recognize economies of scale played a large role in apportioning the cost of procurement of the equipment.

The limitation of the study is the small sample size. The quality-adjusted life years were not included in the calculations as done in many studies.[22] Different studies have utilized different vision screening techniques leading to variability in results.[22]


   Conclusion Top


Our current study compared the use of photoscreeners versus autorefractor and Mohindra retinoscopy as a part of a large community-based pediatric eye care program with data of 2910 children screened. Photoscreening using Plusoptix and 2WIN Adaptica with lay screeners was < seven times the cost incurred and five times faster than the trained optometrists using either autorefractor or Mohindra retinoscopy and thus more cost-effective in screening a large number of young children with at-risk amblyopia at the community level.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Burton MJ, Ramke J, Marques AP, Bourne RR, Congdon N, Jones I, et al. The lancet global health commission on global eye health: Vision beyond 2020. Lancet Glob Health 2021;9:e489-551.  Back to cited text no. 1
    
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National Blindness and Visual Impairment Survey, Current Affairs, GK Today; October, 2019.  Back to cited text no. 2
    
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Jose R, Sachdeva S. School eye screening and the national program for control of blindness. Indian Pediatr 2009;46:205-8.  Back to cited text no. 3
    
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Ganekal S, Jhanji V, Liang Y, Dorairaj S. Prevalence and etiology of amblyopia in Southern India: Results from screening of school children aged 5-15 years. Ophthalmic Epidemiol 2013;20:228-31.  Back to cited text no. 4
    
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Magdalene D, Bhattacharjee H, Choudhury M, Multani PK, Singh A, Deshmukh S, et al. Community outreach: An indicator for assessment of prevalence of amblyopia. Indian J Ophthalmol 2018;66:940-4.  Back to cited text no. 5
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Padhye AS, Khandekar R, Dharmadhikari S, Dole K, Gogate P, Deshpande M. Prevalence of uncorrected refractive error and other eye problems among urban and rural school children. Middle East Afr J Ophthalmol 2009;16:69-74.  Back to cited text no. 6
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Donahue SP, Arnold RW, Ruben JB; AAPOS Vision Screening Committee. Preschool vision screening: What should we be detecting and how should we report it? Uniform guidelines for reporting results of preschool vision screening studies. J AAPOS 2003;7:314-6.  Back to cited text no. 7
    
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Agarwal A, Bloom DE, deLuise VP, Lubet A, Murali K, Sastry SM. Comparing low-cost handheld autorefractors: A practical approach to measuring refraction in low-resource settings. PLoS One 2019;14:e0219501.  Back to cited text no. 8
    
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Available from: https://www.who.int/publications-detail/world-report-on-vision WHO/NMH/NVI/19.12 - [Last accessed on 2019 Oct 08].  Back to cited text no. 9
    
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Lowry EA, de Alba Campomanes AG. Cost-effectiveness of school-based eye examinations in preschoolers referred for follow-up from visual screening. JAMA Ophthalmol 2016;134:658-64.  Back to cited text no. 10
    
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Bang H, Zhao H. Median-based incremental cost-effectiveness ratio (ICER). J Stat Theory Pract 2012;6:428-42.  Back to cited text no. 11
    
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Jarwal PN, Singh R. Evaluation of amblyopia in school going children. DJO 2020;30:46-50.  Back to cited text no. 12
    
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Birch EE, Kelly KR, Wang J. Recent advances in screening and treatment for amblyopia. Ophthalmol Ther 2021;10:815-30.  Back to cited text no. 14
    
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Longmuir SQ, Pfeifer W, Leon A, Olson RJ, Short L, Scott WE. Nine-year results of a volunteer lay network photoscreening program of 147 809 children using a photoscreener in Iowa. Ophthalmology 2010;117:1869-75.  Back to cited text no. 15
    
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Van Heerden A, Leppanen J, Rotheram-Borus MJ, Worthman CM, Kohrt BA, Skeen S, et al. Emerging Opportunities Provided by Technology to Advance Research in Child Health Globally. Glob Pediatr Health. 2020;7:2333794X20917570. doi: 10.1177/2333794X20917570. PMID: 32523976; PMCID: PMC7235657.  Back to cited text no. 16
    
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Rostamzad P, Horwood AM, Schalij-Delfos NE, Boelaert K, de Koning HJ, Simonsz HJ. Plusoptix photoscreener use for paediatric vision screening in Flanders and Iran. Acta Ophthalmol 2020;98:80-8.  Back to cited text no. 17
    
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Van der Ploeg CP, Grevinga M, Eekhout I, Vlasblom E, Lanting CI, van Minderhout HM, et al. Costs and effects of conventional vision screening and photoscreening in the Dutch preventive child health care system. European Journal of Public Health, 2021;31:7-12.  Back to cited text no. 20
    
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Asare AO, Wong AMF, Maurer D, Kulandaivelu Y, Saunders N, Ungar WJ. Economic evaluations of vision screening to detect amblyopia and refractive errors in children: a systematic review. Can J Public Health. 2022;113:297-311. doi: 10.17269/s41997-021-00572-x. Epub 2021 Nov 9. PMID: 34755325; PMCID: PMC8577413.  Back to cited text no. 22
    


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