Vitamin D deficiency and diabetic retinopathy risk

PURPOSE

Vitamin D deficiency may play an important role in the development and progression of diabetic retinopathy. The present study aimed to assess the relationship between vitamin D deficiency and the likelihood of diabetic retinopathy.

METHODS

This nested case-control study was conducted on all type II diabetic patients among the participants of the third phase of the Shahroud eye cohort study. Overall, 278 patients aged 50 to 74 years, 101 in the case group (diabetic retinopathy) and 178 in the control group (diabetic without retinopathy), were assessed. Serum levels of vitamin D on admission were measured for all participants by a radio immunoassay (RIA) technique.

RESULTS

The overall prevalence of vitamin D deficiency (defined as a vitamin D level of less than or equal to 20mg/dL) was 30.7%. Comparison of the serum level of vitamin D across the three groups - without retinopathy, with non-proliferative retinopathy, and with proliferative retinopathy - showed a significantly lower level of this marker in the latter group (P=0.036). Reducing vitamin D to less than or equal to 20ng/mL increased the odds of proliferative retinopathy by 6.25 times (P value: 0.027).

CONCLUSION

Vitamin D deficiency is a potential risk factor for diabetes-related proliferative retinopathy.

The basic reproduction number and prediction of the epidemic size of the novel coronavirus (COVID-19) in Shahroud, Iran

The aim of this study was to estimate the basic reproduction number (R0) of COVID-19 in the early stage of the epidemic and predict the expected number of new cases in Shahroud in Northeastern Iran. The R0 of COVID-19 was estimated using the serial interval distribution and the number of incidence cases. The 30-day probable incidence and cumulative incidence were predicted using the assumption that daily incidence follows a Poisson distribution determined by daily infectiousness. Data analysis was done using 'earlyR' and 'projections' packages in R software. The maximum-likelihood value of R0 was 2.7 (95% confidence interval (CI): 2.1-3.4) for the COVID-19 epidemic in the early 14 days and decreased to 1.13 (95% CI 1.03-1.25) by the end of day 42. The expected average number of new cases in Shahroud was 9.0 ± 3.8 cases/day, which means an estimated total of 271 (95% CI: 178-383) new cases for the period between 02 April to 03 May 2020. By day 67 (27 April), the effective reproduction number (Rt), which had a descending trend and was around 1, reduced to 0.70. Based on the Rt for the last 21 days (days 46-67 of the epidemic), the prediction for 27 April to 26 May is a mean daily cases of 2.9 ± 2.0 with 87 (48-136) new cases. In order to maintain R below 1, we strongly recommend enforcing and continuing the current preventive measures, restricting travel and providing screening tests for a larger proportion of the population.

Visual impairment in the 40- to 64-year-old population of Shahroud, Iran

PURPOSE

To determine the prevalence of visual impairment by age and gender in Shahroud.

METHODS

Using random cluster sampling, 6311 Shahroud inhabitants who were between 40 and 64 years old were invited for ophthalmological examinations. Visual acuity worse than 0.5 LogMAR (20/60) and 1.3 LogMAR (20/400) in the better eye was regarded as low vision and blindness, respectively. The cause of blindness was determined by an ophthalmologist and in a person with more than one cause, the most correctable cause was regarded as the main cause.

RESULTS

This study was conducted on 5190 participants (response rate: 82.2%). On the basis of presenting visual acuity, the prevalence of low vision and blindness was found to be 1.8% (95% confidence interval (CI): 1.4-2.10) and 0.5% (95% CI: 0.3-0.7), respectively. Based on corrected vision, these values were 0.5% (95% CI: 0.3-0.7) and 0.3% (95% CI: 0.1-0.4), respectively. Visual impairment increased with age in women (P<0.001). Uncorrected refractive errors (63.9%), cataract (20.2%), and amblyopia (5.9%) were the most common causes of visual impairment based on presenting vision. Based on corrected vision, however, cataract (42.5%), amblyopia (12.5%), and retinitis pigmentosa (7.5%) were the most common causes of visual impairment.

CONCLUSION

Although the prevalence of visual impairment in the city of Shahroud was determined to be lower than two previous studies in the country, correction of refractive errors and cataract could minimize the rate of visual impairment in this population as they were shown to comprise 85% of the causes of visual impairment. The elderly women need to receive more attention.