Regional Disparities in Prevalence and Causes of Visual Impairment and Blindness, Cataract Surgical Coverage and Ocular Findings in Adults 50 Years and Older in Brazil: A Comparative Analysis between Two Population-Based Cross-Sectional Surveys Performed Within a 10-Year Interval

PURPOSE

To investigate disparities in the prevalence and causes of visual impairment and blindness, cataract surgical coverage, and ocular findings in older adults from two Brazilian geo-socio-demographic areas, São Paulo and Parintins cities.

METHODS

Data from two population-based studies including participants 50 years and older from the cities of São Paulo (São Paulo Eye Study - SPES, 2004) and Parintins (Brazilian Amazon Region Eye Survey - BARES, 2014) were aggregated.

RESULTS

A total of 5318 participants (3677 from SPES;1641 from BARES) were included. The prevalence of severe visual impairment (SVI) and blindness were, respectively, 0.74% (0.46-1.02) and 0.77% (0.48-1.05) in SPES and 1.72% (1.09-2.35) and 3.44% (2.55-4.33) in BARES. SVI and blindness were associated with BARES study [OR = 2.27 (1.30-3.95); p = .004 - SVI] [OR:4.07 (2.51-6.60); p < .001- blindness]; and older age [OR = 10.93 (4.20-28.45); p < .001 - SPES; OR = 17.96 (8.75-36.83); p < .001 - BARES] while higher education level was a protective factor [OR = 0.21 (0.05-0.95) - SPES; p = .042; OR = 0.21 (0.05-0.91); p = .037 - BARES]. Cataract was the main cause of bilateral severe visual impairment (25.93% in SPES and 64.29% in BARES) and bilateral blindness (21.43% in SPES and 35.71% in BARES). Cataract surgical coverage was significantly lower in BARES (36.32%) compared to SPES (57.75%).

CONCLUSION

The prevalence of SVI and blindness was three times higher in older adults from the Brazilian Amazon compared to those living in São Paulo city, despite a 10-year interval between the two studies. These disparities should be mitigated by initiatives to promote access to eye care services targeting underprivileged and remote Brazilian areas.

Impact of pterygium on central corneal thickness measured by optical coherence tomography in older adults

PURPOSE

To measure the central corneal thickness (CCT) using anterior segment optical coherence tomography (AS-OCT) in older adults with and without pterygium from the Brazilian Amazon Region Eye Survey (BARES).

METHODS

BARES is a population-based epidemiological cross-sectional study conducted in Parintins city. Participants were residents ≥45 years of age identified through a door-to-door interview. Eligible participants were invited for a comprehensive eye exam. Pterygium occurrence and severity were assessed by ophthalmologists through slit-lamp examination considering its location (nasal or/and temporal) and severity (lesion with extension <3 mm, ≥3 mm not reaching the pupillary margin or ≥3 mm reaching the pupillary margin). CCTs were obtained and measurements from the more severely affected eye were included. Images were analyzed offline by masked observers.

RESULTS

A total of 671 subjects, 533 (79.4%) with pterygium in at least one eye and 138 (20.6%) without pterygium in either eye, were examined. The mean CCT evaluated by multiple linear regression and adjusted for demographic variables and pterygium severity was 521 ± 34 μm (median = 521; range = 304-665). Decreased CCT was significantly associated with age and pterygium severity. Individuals aged 65-74 years had CCT 7 μm thinner than those aged 45-54 years (p = 0.044), individuals aged 75 years and older had CCT 15 μm thinner than those aged 45-54 years (p = 0.001), and eyes with severe pterygium had CCT 33 μm thinner than eyes without pterygium (p < 0.001).

CONCLUSIONS

The CCT analysis in this population-based sample shows that a thinner cornea is associated with pterygium severity and older age.

Applicability of optical coherence tomography in blue-fronted parrots (Amazona aestiva)

OBJECTIVE

Optical coherence tomography (OCT) measurement of adult blue-fronted parrots (Amazona aestiva), free from infectious, inflammatory or neoplastic systemic diseases and from any ophthalmological illness, aim at its characterization, as well as to standardize the examination technique for the species.

PROCEDURE

Pupillary dilation was achieved with rocuronium bromide (5 mg/mL) at 0, 2, 15, 17, 30, and 32 minutes. The animals were sedated with midazolam maleate (0.5 mg/kg/IM) and anesthetized with propofol (5.0 mg/kg/IV). Measurements were made to evaluate the thickness of the total retina (TR), sensorineural retinal (SR), and ganglion cell complex (GCC), 2 millimeters (mm) from the pecten toward the fovea. OCT data were compared to measurements of retinal histological slides from enucleated eyes of blue-fronted parrots, scanned in automatic fluorescence microscope and measured with by the VS-ASW^® software.

RESULTS

Averages of measurements from the 43 retinas evaluated by OCT were TR: 279.40 micrometers (μm), SR: 255.90 μm, and GCC: 138.60 μm, respectively, and the measurements of six retinas using fluorescence microscopy were 260.30 μm for TR, 238.20 μm for SR, and 129.30 μm for GCC, demonstrating a high correlation coefficient between all measurements (r = .8698, P < .0001). It is also possible to evaluate the anatomy of the retina and to identify its layers, variations and abnormalities using OCT images. Variations were found between the different areas of the retina, both in the images of the histological slides and in the images of the OCT.

CONCLUSION

Optical coherence tomography is a valuable technique for in vivo evaluation of retinal structures in blue-front parrots, providing detailed and accurate images. This method improves the understanding of retinal diseases, monitoring the beginning, progression and therapy of retinal diseases, in the same individuals during longitudinal studies. In comparison to histological investigations, OCT enables imaging in vivo, therefore reducing the number of euthanized animals or enucleated eyes.

Presbyopia and Ocular Conditions Causing Near Vision Impairment in Older Adults From the Brazilian Amazon Region

PURPOSE

To investigate the prevalence and causes of near vision impairment (NVI) in a population of older adults from the Brazilian Amazon Region.

DESIGN

Population-based cross-sectional study.

METHODS

Cluster sampling was used in randomly selecting subjects 45 years of age and older from urban and rural areas of Parintins city, Brazil. Participants underwent ophthalmic examination, including uncorrected (UCNVA), presenting (PNVA), and best-corrected near visual acuity (BCNVA) from each eye; biomicroscopy; funduscopy; and subjective refraction, including testing with additional lenses for near vision optical correction. A principal cause for NVI was assigned by the ophthalmologist and presbyopia was defined as UCNVA ≤ 20/40 changing to > 20/40 with BCNVA. Free-of-charge glasses were provided for those in need.

RESULTS

A total of 2384 subjects were enumerated and 2025 had reliable NVA measurements from both eyes. The prevalence of NVI in the better-seeing eye was 96.5% with UCNVA, decreasing to 81.1% with PNVA and to 20.5% with BCNVA. Presbyopia was the principal cause of NVI in 71.8%, followed by cataract (16.5%) and pterygium (2.5%), and was associated with younger age and high schooling. Glasses for near vision were prescribed and provided to 1414 (69.8%) participants.

CONCLUSIONS

A high prevalence of NVI was detected even in those wearing glasses for near. Prescription and provision of low-cost reading glasses should be considered by Brazilian health authorities to address this easily and promptly correctable form of vision impairment.

Visual acuity and retinal function in patients with Bardet-Biedl syndrome

OBJECTIVE

Bardet-Biedl syndrome is a genetic, multisystem disorder that causes severe visual impairment. This condition is characterized by retinal dystrophy, obesity, digit anomalies, renal disease, and hypogonadism. The purpose of this study was to analyze visual acuity and full-field electroretinogram findings in patients with the Bardet-Biedl syndrome phenotype.

METHODS

The visual acuity of a group of 23 patients (15 males) with ages ranging from 6-36 years (mean = 15.8 ± 6.4; median = 14.7) was assessed. Retinal function was evaluated by full-field electroretinography, and dark-adapted thresholds were assessed.

RESULTS

Visual acuity in the better-seeing eye was 20/40 or better in 5 patients (21.7%), 20/50-20/150 in 13 (56.5%) patients, 20/200-20/400 in 2 (8.7%) patients and worse than 20/400 in one (4.3%) patient. The mean acuity in the better-seeing eye was 0.7 ± 0.6 logMAR (20/100, Snellen equivalent). Scotopic rod and maximal responses were nondetectable in 21 (91.3%) patients, and cone responses were non-detectable in 15 (65.2%) patients. Elevated dark-adapted visual thresholds were observed in all 19 patients who were able to be assessed, with 10 (52.6%) patients having thresholds greater than 30 dB.

CONCLUSIONS

In a relatively young cohort of patients with Bardet-Biedl syndrome, only 21% had 20/40 or better vision. ERG scotopic responses were absent in the majority of cases, with cone responses being observed in less than half of cases. These findings showed the early deleterious effects in retinal function and visual acuity caused by this condition.