What is RAAB?

Rapid assessment of avoidable blindness (RAAB) is a rapid survey methodology. It is a population based survey of blindness and visual impairment and eye care services among people aged 50 years and over.
RAAB can provide the prevalence of blindness and visual impairment, its main causes, the output and quality of eye care services, barriers, cataract surgical coverage and other indicators of eye care services in a specific geographical area.


Why carry out a RAAB survey?

There are two main reasons to collect RAAB survey data on blindness and visual impairment in a community.

  1. To help eye health managers develop intervention programmes for control of blindness based on a community's needs.
  2. To help to monitor existing blindness control programmes and to adjust these programmes as and when required.

RAAB survey data provides only some of the information needed to plan intervention programmes. This situational analysis document PDF (85Kb) reviews all the information needed to plan for blindness control programmes at the district level.



What RAAB is not

  • RAAB is not a case-finding exercise: it will not provide a list of names and addresses of all people who are blind due to (for example) cataract in an area.
  • RAAB is not a detailed blindness survey: it provides a reasonably accurate estimate of the prevalence of blindness, and the proportion that is avoidable in a geographic area. RAAB is not designed to give accurate estimates of the prevalence of specific causes of blindness and does not measure posterior segment disease in detail.
  • RAAB focuses on people aged 50 years and above and so it does not give an estimate of childhood blindness, which is better measured through the Key Informant Method. RAAB 5 provides data on uncorrected refractive errors, spectacle coverage and uncorrected presbyopia in people aged 50+. It does not provide data on refractive errors in people younger than 50 years.


Who can carry out a RAAB survey?

The entire process of carrying out a RAAB survey, from planning to the collection of field data, data analysis and report writing, can be conducted by local staff. 3-5 teams (never more than 5, because the IOV assessment becomes impossible) with transport can cover the usual required sample size in a minimum period of 5-6 weeks, including 1 week of training. The collection of data can be done by local ophthalmologists, or residents in ophthalmology, together with an assistant who does not need to be medically trained. The use of a local guide to introduce the survey team in the community is essential. Local staff can also enter the data directly into the software package.



Want to carry out your own RAAB survey?

Good planning and organisation are vital for success
Although RAAB has the word 'rapid' in its title it is neither easy nor straightforward to undertake. If the RAAB is not undertaken carefully and to a high quality then it will give biased results which will not help with planning or monitoring and will have wasted time and money. RAABs therefore need to be planned and undertaken carefully and we strongly advise you to co-ordinate with an ICEH certified RAAB trainer when planning a RAAB. The trainer can help with the preparations for the RAAB as well as train the staff and monitor the fieldwork during its early stages. Contact details for regional trainers for RAAB are given on this page.

All RAAB activities should be organised by a Survey Coordinator who starts work before the actual field survey takes place;

  • Developing the sampling frame for the survey: This has to be done by the RAAB trainer before the start of the actual RAAB training, to ensure that the sampling frame is of good quality.
  • Carrying out a baseline needs assessment
  • Selecting the clusters to be examined: This has to be done during the training in the presence of all survey staff. This is to avoid any suspicion of bias in the selection of clusters.
  • Recruiting survey personnel
  • Arranging scheduling and transport & equipment logistics
  • Organising and ensuring the quality of the staff training
  • Managing the data - collecting survey records, managing data entry, analysis and report writing



Tips for a successful RAAB survey


  1. Work with a certified RAAB trainer while planning a RAAB.
  2. Do not underestimate the amount of time and effort involved in undertaking a RAAB.
  3. Plan a RAAB during a favourable season.
  4. Plan a RAAB where the information is needed to plan, monitor and/or advocate for services, working with local eye care providers.
  5. The certified RAAB trainer should ensure that the sampling frame is appropriate for selecting clusters before the start of the training.
  6. Don't leave things until the RAAB starts - make sure sufficient funds in place for all aspects of the RAAB (training, staff, transport etc) and that relevant authority approvals, logistics, equipment, printing, office and so on are all ready before the RAAB is started.


  1. A RAAB certified trainer should undertake the training for RAAB.
  2. The venue for the class room training part should be a simple room that has facilities for seating, projection and place for practicing vision tests.
  3. All members of the survey teams should attend all the training sessions.
  4. The equipment that will be used in the RAAB survey should always be part of the training sessions.
  5. Pre-training arrangements should include decision on where the IOV exercise and pilot RAAB survey will be done and be part of the training time table. Hans Limburg usually uses one of the selected clusters for the field practice. So this is selected on day 1 or day 2.


  1. The RAAB fieldwork should start immediately after the training and should continue without long gaps.
  2. The RAAB protocol should be followed, especially the examination of eligible people in their own houses.
  3. The teams who will undertake the RAAB must commit for the full time duration including training and a per-diem should be agreed.
  4. For team recruitment consider local customs (e.g have female team members in communities where there is such need) and make sure the team are prepared for long hours of walking in communities. Fieldwork experience is an advantage.
  5. Data should be double-entered as soon as possible after data collection (ideally on the same day) to correct possible errors. This data should be backed up regularly.

Reporting and service provision

  1. "No Survey without Service" should be emphasized. People identified with eye problems in the survey should be referred to an appropriate service.
  2. The results of the RAAB must be written up in a report and presented to the relevant stakeholders.
  3. Stakeholders should be encouraged to use RAAB results to inform planning of services.
  4. Advocacy after RAAB on the results to the authorities where RAAB was carried out and information sharing is absolutely important to build service delivery initiatives.


Diabetic retinopathy module in RAAB

It is well established that the prevalence of diabetes is rapidly increasing worldwide. However, there is little information on the prevalence of diabetic retinopathy (DR) in different parts of the world and particularly in low and middle income settings. The DR module for RAAB (RAAB+DR) was developed as a relatively rapid method for estimating the prevalence of diabetes and DR in the population aged 50 years in order to inform diabetic eye services.

RAAB+DR follows the standard RAAB methodology, with two additional components:

  • Assessment of the diabetes status of survey participants
  • Assessment of DR among survey participants identified as having diabetes

In addition to RAAB outputs, RAAB+DR provides the following estimates for population aged 50 years:

  • The prevalence of diabetes
  • The prevalence of DR and sight threatening diabetic retinopathy
  • The proportion of people with known diabetes who have had a previous fundus examination
  • Indication of glycaemic control among people with diabetes

What RAAB+DR is not
RAAB+DR only includes people aged 50 years and older and cannot estimate the prevalence of diabetes and DR in younger age groups. To keep the survey relatively rapid, RAAB+DR uses simplified examination procedures that can be conducted at the household, which has implications for the degree of clinical detail collected. Diabetes diagnosis is based on history of diabetes or elevated RBG rather than a fasting blood glucose or oral glucose tolerance test. This may slightly underestimate the prevalence of diabetes. DR assessment is by dilated examination by direct and indirect ophthalmoscope using a simplified grading system. RAAB+DR therefore does not provide comprehensive detail on the level of DR.

When should RAAB+DR be conducted?
Including the DR component in RAAB adds significantly to the time, resources, cost and complexity of the survey and should only be undertaken if a)the prevalence of diabetes is expected to be high (e.g. >15% among people aged 50+ years), b)there are sufficient resources, experienced DR graders and time c)diabetic and DR services are available and accessible and d) the information will be used for planning DR services. If these are not available, a standard RAAB should be undertaken.



RAAB software package

The RAAB software package is for the entry and analysis of data from rapid assessment of avoidable blindness surveys (RAABs). The package contains software (Windows only), supporting documentation and training materials. There are currently two versions of the RAAB package - RAAB5 and RAAB6. You can download both versions through the link on the Download page.
Features in RAAB5 include: Summary reports on key outputs, Optional Diabetic Retinopathy module plus supporting materials, Spanish lanaguage version, Improved survey and IOV forms, support for Windows Vista, 7 and 8. RAAB 5 also includes tables on Functional Low Vision: people aged 50+ with best corrected VA<6/18 to PL+ in the better eye, which cannot be treated anymore. With increasing life expectancy, an increasing treatment options in eye care, avoidable blindness is reducing but unavoidable blindness is increasing.
RAAB6 has an additional level of visual acuity of VA<6/12. For this, all coding, manuals, survey forms and slide sets have been updated. RAAB6 has all the functions of RAAB5, plus VA<6/12. This means that RAAB 6 has no backward compatibility: you cannot run any data files generated in previous versions of RAAB in RAAB6 software. Therefore, RAAB5 software is still required to provide that backward compatibility.



More information

For details about ICEH certification for RAAB trainers, please contact Hannah Kuper, hannah.kuper@lshtm.ac.uk, Sarah Polack, sarah.polack@lshtm.ac.uk or Islay MacTaggart, Islay.Mactaggart@lshtm.ac.uk.


We would like to thank the organisations which have generously supported the development of RAAB: Sightsavers, ORBIS, CBM, International Agency for the Prevention of Blindness, Fight for Sight and Fred Hollows Foundation



Further reading

  • Review of Blindness and Visual Impairment in Paraguay: Changes Between 1999 and 2011. Duerksen R, Limburg H, Lansingh VC, Silva JC. Ophthalmic Epidemiol. 2013 Oct;20(5): 301–7. https://www.ncbi.nlm.nih.gov/pubmed/24070101
  • Rapid assessment of avoidable blindness and diabetic retinopathy in Taif, Saudi Arabia. Al Ghamdi AH, Rabiu M, Hajar S, Yorston D, Kuper H, Polack S. Br J Ophthalmol. 2012 Sep;96(9):1168-72. Epub 2012 Jul 11. Free abstract: https://www.ncbi.nlm.nih.gov/pubmed/22790436.
  • A rapid assessment of avoidable blindness in Southern Zambia. Lindfield R, Griffiths U, Bozzani F, Mumba M, Munsanje J. PLoS One. 2012;7(6):e38483. doi: 10.1371/journal.pone.0038483. Epub 2012 Jun 21. Free access: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3380852/.
  • The Nakuru posterior segment eye disease study : Methods and prevalence of blindness and visual impairment in Nakuru, Kenya. Mathenge W, Bastawrous A, Foster A, Kuper H. Ophthalmology. 2012 Oct;119(10):2033-9. doi: 10.1016/j.ophtha.2012.04.019. Epub 2012 Jun 19. Free abstract https://www.ncbi.nlm.nih.gov/pubmed/22721919
  • Rapid assessment of avoidable blindness and diabetic retinopathy in Chiapas, Mexico. Polack S, Yorston D, López-Ramos A, Lepe-Orta S, Baia RM, Alves L, Grau-Alvidrez C, Gomez-Bastar P, Kuper H. Ophthalmology. 2012 May;119(5):1033-40. Epub 2012 Feb 18. Free abstract from PubMed: https://1.usa.gov/A4KRKD
  • Results of a rapid assessment of avoidable blindness (RAAB) in Eritrea. Müller A, Zerom M, Limburg H, Ghebrat Y, Meresie G, Fessahazion K, Beyene K, Mathenge W, Mebrahtu G. Ophthalmic Epidemiol. 2011 Jun;18(3):103-8. doi: 10.3109/09286586.2010.545932. Free abstract from PubMed: https://www.ncbi.nlm.nih.gov/pubmed/21609238.
  • Findings from a rapid assessment of avoidable blindness (RAAB) in Southern Malawi. Kalua K, Lindfield R, Mtupanyama M, Mtumodzi D, Msiska V. PLoS One. 2011 Apr 25;6(4):e19226. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3081843/.
  • Rapid assessment of avoidable blindness in the Occupied Palestinian Territories. Chiang F, Kuper H, Lindfield R, Keenan T, Seyam N, Magauran D, Khalilia N, Batta H, Abdeen Z, Sargent N. PLoS One. 2010 Jul 29;5(7):e11854. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2912325.
  • Rapid assessment of avoidable blindness in Kunming, China. Wu M, Yip JLY, Kuper H. Ophthalmology 2008 Jun;115(6):969-74. https://www.ncbi.nlm.nih.gov/pubmed/17953988.
  • Rapid assessment of avoidable blindness in Negros Island and Antique district, Philippines. Eusebio C, Kuper H, Polack SR, Enconada J, Tongson N, Dionio D, DumDum A, Limburg H, Foster A. Br J Ophthalmol 2007 Dec;91(12):1588-92. https://bjo.bmj.com/content/91/12/1588.

Browse all articles about RAAB on this website.