Elsevier

Ophthalmology

Volume 119, Issue 10, October 2012, Pages 2033-2039
Ophthalmology

Original article
The Nakuru Posterior Segment Eye Disease Study: Methods and Prevalence of Blindness and Visual Impairment in Nakuru, Kenya

https://doi.org/10.1016/j.ophtha.2012.04.019Get rights and content

Objectives

To estimate the prevalence of blindness and visual impairment (VI) in adults aged ≥50 years in the Nakuru district of Kenya and to identify sociodemographic risk factors for these conditions. We also sought to validate the Rapid Assessment of Avoidable Blindness (RAAB) methodology.

Participants

There were 5010 subjects enumerated for this study. Of these, 4414 participants underwent examination, for a response rate of 88.1%.

Design

Cross-sectional, population-based survey.

Methods

Cluster random samplings with probability proportionate to size procedures were used to select a representative cross-sectional sample of adults aged ≥50 years. Each participant was interviewed, had distance visual acuity (VA) measured with reduced logarithm of the minimal angle of resolution tumbling-E chart, underwent autorefraction, and thereby had measurements of presenting, uncorrected, and best-corrected VA. All participants, regardless of vision, underwent detailed ophthalmic examinations including slit-lamp assessment and dilated retinal photographs.

Main Outcome Measures

Visual acuity of <6/12.

Results

A representative sample of 4414 adults were enumerated (response rate, 88.1%). The prevalence of blindness (VA < 3/60 in better eye) was 1.6% (95% confidence interval [CI], 1.2–2.1%) and of VI, 0.4% (95% CI, 0.3–0.7%); 8.1% (95% CI, 7.2–9.2%); and 5.1% (95% CI, 4.3–6.1%) were severely (<6/60–3/60), moderately (<6/18–6/60), or mildly (<6/12–6/18) visually impaired, respectively. Being male, having less education, having Kalenjin tribal origin, and being ≥80 years old were associated with increased blindness prevalence. Prevalence estimates were comparable to a RAAB performed in the same area 2 years earlier.

Conclusions

This survey provides reliable estimates of blindness and VI prevalence in Nakuru. Older age and tribal origin were identified as predictors of these conditions. This survey validates the use of RAAB as a method of estimating blindness and VI prevalence.

Financial Disclosure(s)

The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Section snippets

Methods/Design

The study fieldwork was carried out in 2 phases from January 2007 to June 2007 and from April 2008 to November 2008.

Study Participation and Response Rates

There were 5010 subjects enumerated for this study. Of these, 4414 participants underwent examination, for a response rate of 88.1%. The response rate was similarly high among men (89.2%) and women (86.5%). Of the nonrespondents, 584 (98%) were away working or visiting family outside the cluster location and 12 (2%) refused to participate; none were excluded as a result of inability to communicate.

Comparison of Responders and Nonresponders

Details about gender were available for all of the nonresponders, whereas age was available for

Discussion

This study describes the vision status of a random sample of Kenyan people aged ≥50 years living in Nakuru district using comprehensive ophthalmic examination techniques. The results confirm that prevalence of blindness is relatively low as suggested by recent RAAB surveys4, 21 and that it may be declining compared with earlier surveys.22

The prevalence of bilateral blindness in this study (1.6% [95% CI, 1.2–2.1]) is similar to that found in the RAAB performed in the same district in 2005 (2.0%

References (22)

  • W. Mathenge et al.

    Rapid assessment of avoidable blindness in Nakuru district, Kenya

    Ophthalmology

    (2007)
  • Visual impairment and blindnessFact Sheet no. 282

  • S. Resnikoff et al.

    Global data on visual impairment in the year 2002

    Bull World Health Organ

    (2004)
  • B. Dineen et al.

    A proposed rapid methodology to assess the prevalence and causes of blindness and visual impairment

    Ophthalmic Epidemiol

    (2006)
  • W. Mathenge et al.

    Rapid assessment of avoidable blindness in Western Rwanda: blindness in a postconflict setting [report online]

    PLoS Med

    (2007)
  • A. Muller et al.

    Results of a rapid assessment of avoidable blindness (RAAB) in Eritrea

    Ophthalmic Epidemiol

    (2011)
  • K. Kalua et al.

    Findings from a rapid assessment of avoidable blindness (RAAB) in Southern Malawi [report online]

    PLoS Med

    (2011)
  • C. Habiyakire et al.

    Rapid assessment of avoidable blindness and cataract surgical services in Kilimanjaro Region, Tanzania

    Ophthalmic Epidemiol

    (2010)
  • S. Kikira

    RAAB survey of Pemba and Unguja islands, Zanzibar

    Community Eye Health

    (2007)
  • H. Faal et al.

    National survey of blindness and low vision in The Gambia: results

    Br J Ophthalmol

    (1989)
  • Y. Berhane et al.

    Prevalence and causes of blindness and low vision in Ethiopia

    Ethiop J Health Dev

    (2007)
  • Cited by (28)

    • The potential health benefits of dietary natural plant products in age related eye diseases

      2020, Heliyon
      Citation Excerpt :

      It has the potentials to effectively inhibit lipid peroxidation, reactive oxygen species, decrease inflammatory cytokines, suppress oxidative stress, and increase antioxidant enzymes in age-related eye diseases (Figure 2) (Suryanarayana et al., 2005; Xu et al., 2017). Many researchers have documented positive effects of curcumin against age-related eye diseases such as cataract (Pandya et al., 2000; Manikandan et al., 2010a) and diabetic retinopathy (Zuo et al., 2013; Yang et al., 2018). The work of Mandal et al. (2009) reported that supplementation of 0.2% curcumin in rat-diets for two weeks inhibited NF-kΒ activation and downregulated inflammatory genes which leads to retinal neuroprotection.

    • Diagnostic Accuracy of Rapid Assessment of Avoidable Blindness: A Population-based Assessment

      2020, American Journal of Ophthalmology
      Citation Excerpt :

      However, it is necessary to evaluate the diagnostic ability of the RAAB examination for its limitations. The Nakuru Posterior Segment Eye Disease Study showed that the prevalence of blindness evaluated from a population-based survey was very close to the RAAB estimates performed in the same area 3 years earlier.30 However, these 2 studies were not performed concurrently and the sampled population was different.

    View all citing articles on Scopus

    Manuscript no. 2011-1718.

    Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

    Supported by grants from the British Council for the Prevention of Blindness (BCPB) and the Fred Hollows Foundation [Wanjiku Mathenge]. Andrew Bastawrous is funded by a Medical Research Council and Fight for Sight Fellowship and is in receipt of an International Glaucoma Association Award and a BCPB pump-priming grant.

    View full text