Retinal vein occlusion in Armenia

Seasonal variation in the occurrence of retinal vein occlusion: a 4-year cross-sectional study

BACKGROUND

Retinal vein occlusion (RVO) is a common retinal vascular disease that causes a loss of vision. Therefore, we investigated whether there is seasonal variation in the onset of RVO, to examine the possibility of preventing it.

METHODS

Patients with RVO who were treated at the Juntendo University Urayasu Hospital between April 2013 and March 2017 were included in this retrospective study. The season in which the RVO occurred was recorded for each case, and the cases were grouped into six 2-month periods based on the month of RVO, and classified by age, sex and hypertension status. The frequency of occurrence of RVO across seasons was compared using a chi-squared test.

RESULTS

A total of 348 patients with RVO presented during the study period, with information regarding the date of RVO onset. The cohort of 348 consisted of 167 males and 181 females who, overall, had a mean age of 64.0 years (range 17-96 years). The highest incidence of RVO onset was during January/February, with the lowest incidence during July/August. Patient age, sex and hypertension status did not influence the results.

CONCLUSIONS

The seasonal onset of RVO tended to be higher in January/February and May/June, and lower in July/August. These findings suggest that eyecare professionals should be more vigilant in watching for the occurrence of RVO during winter and the rainy season, regardless of the patient's sex, age or hypertension status.

Prevalence, pattern and risk factors of retinal vein occlusion in an elderly population in Nepal: the Bhaktapur retina study

Background

This study aims to explore the prevalence, pattern and risk factors of retinal vein occlusion (RVO) in an elderly population of Nepal.

Method

One thousand eight hundred sixty subjects of age 60 years and above were enrolled in a population-based, cross-sectional study. Detailed history, visual acuity, anterior segment and posterior segment examinations were done. Blood pressure, non-fasting blood sugar, body mass index and abdominal girth were measured. Retinal vein occlusions were further divided into branch retinal (BRVO), hemi-retinal and central retinal vein occlusion (CRVO).

Result

Age ranged from 60 to 95 years with a mean of 69.64 ± 7.31 years. Overall population prevalence for RVO was 2.95% (95% Confidence interval (CI): 2.23–3.83), BRVO 2.74% (95% CI: 2.05–3.58) and CRVO 0.21% (95% CI: 0.06–0.55). BRVO was seen in 51 subjects (92.73%) and CRVO in 4 (7.27%). Among the total RVO, unilateral and bilateral involvement was 85.45% and 14.55%, respectively. Among the subjects with BRVO and CRVO, 37.25% and 50% had low vision, respectively. The risk of RVO increased with ageing and was more among males. There was an increased risk of RVO among those with hypertension, and with diabetes and hypertension. There was also an increased risk of RVO among subjects with hypermetropia, those with pseudophakia and those who were smokers and consumed alcohol.

Conclusion

Retinal vein occlusion is a common retinal vascular disorder in the elderly population of Nepal. The main risk factors for RVO were increasing age and hypertension.

Climate and season: the effects on ophthalmic diseases

Seasonal changes and climate have a significant impact on human health. Diseases influenced by temperature and climate conditions are likely to undergo dynamic pattern shifts with consequent impact on human health. A number of infectious and non-infectious ophthalmic diseases are influenced by temperature and seasonality. Awareness of this is important from public and global health perspective in addition to resource allocation strategies. We examine the evidence for a seasonal pattern to ophthalmic diseases and assess the possible impact of climate change.

Central Retinal Vein Occlusion Associated With Severe Vitamin D Deficiency

Central retinal vein occlusion (CRVO) is thought to occur due to thrombotic occlusion of the central retinal vein at or just posterior to the lamina cribrosa. Studies have shown that the incidence of CRVO may be higher in winter to early spring, suggesting that low vitamin D levels may play a role; however, no studies have measured vitamin D levels in patients with CRVO. In addition, there is mounting evidence that patients with vitamin D deficiency may be predisposed to thrombotic events. The authors report a case of central retinal vein occlusion associated with marked vitamin D deficiency.

Seasonal variations in the occurrence of retinal vein occlusion: a five-year nationwide population-based study from Taiwan

PURPOSE

To determine whether seasonal variation exists in the incidence of retinal vein occlusion.

DESIGN

Retrospective, nationwide population-based administrative database study.

METHODS

We collected data on outpatient and emergency visits for the period from January 1999 through December 2003 from the Taiwan National Health Insurance Research Database, a source that covers more than 96% of Taiwan's 23 million citizens. In total, 20,792 patients with a first-time diagnosis of either central retinal vein occlusion or branch retinal vein occlusion (The International Classification of Disease, Ninth Revision, Clinical Modification [ICD-9-CM] code 362.35 or 362.36, respectively) were identified. Monthly incidence of retinal vein occlusion was obtained for each age group, each gender group, and for the entire sample. The autoregressive integrated moving average method of analysis was adopted to examine seasonality in the monthly incidence of retinal vein occlusion.

RESULTS

The monthly incidence rates of retinal vein occlusion revealed significant seasonality, with a clear peak in January for each age group and each gender group, as well as for the total sample.

CONCLUSIONS

Our study demonstrates significant seasonal variations in the retinal vein occlusion incidence, with the peak occurrence in the winter month of January.

The impact of ocular blood flow in glaucoma

Two principal theories for the pathogenesis of glaucomatous optic neuropathy (GON) have been described--a mechanical and a vascular theory. Both have been defended by various research groups over the past 150 years. According to the mechanical theory, increased intraocular pressure (IOP) causes stretching of the laminar beams and damage to retinal ganglion cell axons. The vascular theory of glaucoma considers GON as a consequence of insufficient blood supply due to either increased IOP or other risk factors reducing ocular blood flow (OBF). A number of conditions such as congenital glaucoma, angle-closure glaucoma or secondary glaucomas clearly show that increased IOP is sufficient to lead to GON. However, a number of observations such as the existence of normal-tension glaucoma cannot be satisfactorily explained by a pressure theory alone. Indeed, the vast majority of published studies dealing with blood flow report a reduced ocular perfusion in glaucoma patients compared with normal subjects. The fact that the reduction of OBF often precedes the damage and blood flow can also be reduced in other parts of the body of glaucoma patients, indicate that the hemodynamic alterations may at least partially be primary. The major cause of this reduction is not atherosclerosis, but rather a vascular dysregulation, leading to both low perfusion pressure and insufficient autoregulation. This in turn may lead to unstable ocular perfusion and thereby to ischemia and reperfusion damage. This review discusses the potential role of OBF in glaucoma and how a disturbance of OBF could increase the optic nerve's sensitivity to IOP.