Intraocular pressure after exposure to moderate altitude.

BACKGROUND: To study intraocular pressure (IOP) alteration in healthy individuals following a rapid effortless increase in altitude from 1900 m above sea level (ASL) to 3740 m ASL. METHODS: Intraocular pressure, blood pressure, pulse rate, and arterial oxygen tension were determined in both eyes of healthy volunteers at the lower altitude. Participants were taken to a higher altitude of 3740 m ASL (1840-m altitude gain) via gondola lift, which took 30 minutes. All measurements were repeated at the higher altitude. Pearson and Spearman correlation analysis was conducted to assess the correlations among the variables. A paired t-test and linear regression were also used to compare IOP before and after ascending. The accepted level of significance for all tests was p <0.05. RESULTS: Fifty-four healthy volunteers participated in the study. Four eyes of three subjects with IOP higher than 21 mmHg were excluded. Intraocular pressure ± SD (range) decreased from 14.9 ± 2.6 mmHg (9-21 mmHg) to 14.3 ± 2.4 mmHg (11-20 mmHg) (p = 0.02) after the ascent. Arterial oxygen saturation decreased from 95.4 % to 91.5 % (p < 0.001). Neither of the participants complained of any ocular or systemic symptoms during or after ascending to the higher altitude. Mean IOP, before and after ascending, was positively correlated with systolic blood pressure before and after the increase in altitude (Pearson correlation coefficient, 0.41, p = 0.002 and Pearson correlation coefficient, 0.37, p = 0.006, respectively). Intraocular pressure changes did not correlate with age, pulse rate, or arterial oxygen saturation. CONCLUSION: A rapid, effortless increase in altitude (over a moderate range in altitude) decreases IOP in healthy individuals. The observed decrease may not be clinically significant; however, it shows the versatility of IOP control mechanisms in response to alteration in altitude and temperature.

Association of Htra1 gene polymorphisms with the risk of developing AMD in Iranian population.

BACKGROUND: Half of the cases of vision loss in people under 60 years of age have been attributed to age-related macular degeneration (AMD). This is a multifactorial disease with late onset. It has been demonstrated that many different genetic loci are implicated in the risk of developing AMD in different populations. In the current study, we investigated the association of high-temperature requirement A-1 (HTRA1) gene polymorphisms with the risk of developing AMD in the Iranian population. METHODS: Genomic DNA samples were extracted from 120 patients with AMD and 120 healthy age- and sex-matched controls. A 385 base-pair fragment of the HTRA1 gene promoter region was amplified using the polymerase chain reaction (PCR) technique and sequenced. The frequencies of the alleles were calculated and statistical analysis was performed using SPSS software. RESULTS: Our study demonstrated that the rate of polymorphisms rs11200638 -625 G>A and rs2672598 -487T>C were significantly greater in AMD patients than in healthy controls from the Iranian population. CONCLUSIONS: The results of our study indicate that HTRA1 gene promoter region polymorphisms are associated with the risk of developing AMD in the Iranian population.

Complement Factor H Y402H and LOC387715 A69S Polymorphisms in Association with Age-Related Macular Degeneration in Iran.

PURPOSE: To determine the frequency of complement factor H (Y402H) and age related macular degeneration susceptibility gene 2 (A69S) single nucleotide polymorphisms in patients with age-related macular degeneration (AMD) and in matched non-AMD controls in an Iranian population. METHODS: Seventy patients with AMD and 86 age- and sex-matched controls were recruited and examined. Peripheral blood sample was obtained from all subjects for DNA extraction and direct sequencing of Y402H and A69S genes. Odds ratios (ORs) with 95% confidence intervals (CIs) for the association of Y402H and A69S polymorphisms with AMD were determined. RESULTS: The frequencies of both homozygous and heterozygous genotypes were significantly higher in cases than controls for both Y402H and A69S polymorphisms. In comparison to the wild genotypes, OR for AMD associated with Y402H and A69S polymorphisms were 1.9 (95% CI, 1.1-3.2) and 2.2 (95%CI, 1.6-3.1), respectively. Joint risk analysis considering both genes revealed a higher risk of AMD when polymorphisms were present for both genes. CONCLUSION: Y402H and A69S polymorphisms were strongly associated with AMD in this Iranian population.