Prevalence and Causes of Blindness and Visual Impairment and Their Associated Risk Factors, in Three Tribal Areas of Andhra Pradesh, India

Objective: To assess the prevalence of blindness and visual impairment (VI), their associated causes and underlying risk factors in three tribal areas of Andhra Pradesh, India and compare this data in conjunction with data from other countries with low and middle income settings. Methods: Using a validated Rapid Assessment of Avoidable Blindness methodology, a two stage sampling survey was performed in these areas involving probability proportionate to size sampling and compact segment sampling methods. Blindness, VI and severe visual impairment (SVI) were defined as per the WHO guidelines and Indian definitions. Results: Based on a prior enumeration, 7281 (97.1%) subjects were enrolled (mean age = 61.0+/−7.9 years). Based on the presenting visual acuity (PVA), the prevalences of VI, SVI and blindness were 16.9% (95% CI: 15.7–18.1), 2.9% (95% CI: 2.5–3.4), and 2.3% (95% CI: 1.9–2.7), respectively. When based on the Pinhole corrected visual acuity (PCVA), the prevalences were lower in VI (6.2%, 95% CI: 5.4–6.9), SVI (1.5%, 95% CI: 1.2–1.9) and blindness (2.1%, 95% CI: 1.7–2.5). Refractive error was the major cause of VI (71.4%), whereas, cataract was the major cause of SVI and blindness (70.3%). Based on the PVA, the odds ratio (OR) of blindness increased in the age groups of 60–69 years (OR = 3.8, 95% CI: 2.8, 5.1), 70–79 years (OR = 10.6, 95% CI: 7.2, 15.5) and 80 years and above (OR = 30.7, 95% CI: 19.2, 49). The ORs were relatively higher in females (OR = 1.3, 95% CI: 1.0, 1.6) and illiterate subjects (OR = 4.3, 95% CI: 2.2, 8.5), but lower in those wearing glasses (OR = 0.2, 95% CI: 0.1, 0.4). Conclusions: This is perhaps the first study to assess the prevalence of blindness and VI in these tribal regions and the majority of the causes of blindness and SVI were avoidable (88.5%). These findings may be useful for planning eye care services in these underserved regions

Screening for latent tuberculosis in refugees with renal failure

Refugee camps are prone for easy spread of infections of various kinds and tuberculosis (TB) is no exception. Refugees with renal failure are often a vulnerable group because they are immunocompromised due to reasons such as poor nutrition, overcrowding and immune suppression due to renal failure. Latent pulmonary TB is a particular problem in this patient population as it is not easily diagnosed and has immense potential for spread. Tuberculin Skin Test (TST), although easy to perform and is cost-effective, suffers from the limitations of giving false positive results due to cross-reaction with the vaccination. Chest radiography though cheap, has not yet been validated in refugee populations for this purpose. Sputum analysis shows promise due to ease of performing but again has not been validated in refugees. Newer assays such as IF-γ show great promise but needs large scale studies for validation and cheaper assays need to be developed for use in resource poor refugee setting. In short, an ideal tool for effective screening of latent TB in refugees with renal failure is lacking. Future studies are required to identify this ideal tool

Prevalence of blindness, SVI and VI in different studies in India and neighboring countries.

<p>*: Year of study not available; CI: Confidence Interval;</p><p>**: Confidence Interval calculated using binomial proportions; SVI: Severe Visual Impairment; VI: Visual Impairment; NA: Data not available.</p

Pinhole Corrected Visual Acuity: Risk factors for VI, SVI and Blindness.

<p>VI: Visual Impairment; SVI: Severe Visual Impairment; CI: Confidence Interval; Ref: Reference group; OR: Odds Ratio.</p

Causes of VI, SVI and blindness.

<p>VI: Visual Impairment; SVI: Severe Visual Impairment.</p

Prevalence of Blindness, SVI and VI based on presenting and Pinhole-corrected visual acuity.

<p>VI: Visual Impairment; SVI: Severe Visual Impairment; CI: Confidence Interval.</p

Baseline characteristics of participants and non-participants.

<p>SD: Standard Deviation.</p

Presenting Visual Acuity: Risk factors for VI, SVI and blindness.

<p>VI: Visual Impairment; SVI: Severe Visual Impairment; CI: Confidence Interval; Ref: Reference group; OR: Odds Ratio.</p

Causes of blindness, SVI and VI in different studies in India and neighbouring countries.

<p>*: For both Blindness and Severe Visual Impairment; RE: Refractive error; SVI: Severe Visual Impairment; VI: Visual Impairment; NA: Data not available.</p