Introduction

With the rapid development of ophthalmic diagnosis and treatment technology, Optical Coherence Tomography (OCT) has become one of the most important tools for diagnosing ophthalmic diseases1. Among them, Spectralis OCT, as a new type of OCT technology, provides new possibilities for accurate diagnosis of retinal diseases by providing higher image resolution and deeper tissue penetration2.

Epiretinal Membrane (ERM) is a retinal disease that affects vision and mainly occurs in middle-aged and elderly populations3. Due to the fact that the macular membrane may not have obvious symptoms in the early stages of onset, and traditional ophthalmic examination methods are difficult to accurately diagnose, it is crucial to find an efficient and accurate screening tool for the early diagnosis and intervention of this disease.

Spectralis OCT can clearly display the structure and morphology of each layer of the retina in the macular area, thereby accurately identifying the presence and degree of the macular membrane4. Its advantage is that it has an additional colorful fundus photo compared to ordinary OCT, which can save time and cost in fundus photography. Moreover, it has a higher resolution and can distinguish some macular membranes that are not easily observed in fundus photography. However, there is still relatively less research on the application of Spectralis OCT in macular membrane screening, and there is a lack of large-scale and systematic epidemiological investigations3,5,6.

As one of the regions with a relatively developed economy and a high degree of aging population in China, the health issues of middle-aged and elderly people in Fujian are increasingly receiving attention. In order to better understand the prevalence of ERM in the middle-aged and elderly population in Fujian province and provide scientific basis for its prevention and treatment, this study planed to use Spectralis OCT technology to conduct a large-scale screening of the middle-aged and elderly population in this region.

Through this study, we hope to provide strong support for the early detection and intervention of ERM in the middle-aged and elderly population in Fujian region, and also provide useful reference and guidance for the prevention and treatment of eye diseases in other middle-aged and elderly populations. In addition, the results of this study will also contribute to promoting the application and development of Spectralis OCT technology in the field of ophthalmology, and contribute new strength to the diagnosis and treatment of ophthalmic diseases.

Materials and methods

Study design

A population based cross-sectional study, Fujian Eye Study (FJES) was performed on residents aged 50 years and older in Fujian Province, Southeast China from May 2018 to October 2019. Random cluster sampling was used in this investigation, and the calculation formula and sample size have been reported5. A clinical study registry was obtained for the 2018–2019 FJES study (register number: ChiCTR2100043349, registration date: 2021-02-21) and the study protocol was approved by the Ethics Committee of Xiamen Eye Center afliated with Xiamen University (Acceptance number: XMYKZX-KY-2018-001). This study follows the Helsinki Declaration and written informed consent was obtained from all participants.

Participants

Participants underwent a comprehensive physical examination in a mobile clinic. Those who were unable to participate in on-site examination in the screening were asked for the consent of home visits and simple ophthalmic examinations.

On-site examination

The main contents of this study include the following: questionnaire (age, sex, and race; educational background, income level, occupation, etc.); visual acuity, refraction, intraocular pressure (IOP), fundus photograph and Spectralis OCT. The flowchart of field screening has been reported7.

A fundus photograph of each eye was taken using a scanning laser device (Digital Fundus Camera, VISUCAM 524, Goeschwitzer Strasse 51–52, 07,745 Jena, Germany) and Spectralis OCT (Spectralis OCT, Heidelberg Engineering GmbH 69,121, Heidelberg, Germany) was used for high-resolution imaging of the optic disc and central retina in both eyes. The protocols have been reported5.

Statistical analysis

Data analysis was carried out using Stata/SE statistical software (Stata for Windows, version 15.1, StataCorp LLC, Lakeway Drive, College Station, TX, USA). A χ2 tests was used for categorical variables. Linear regression was used to determine whether ERM occurrence and potential factors were related. Logistic regression was used for correlation degree of each group. Multiple logistic regression was used to assess the association of factors with ERM. The odds ratios (ORs) or r values with 95% confidential intervals (CIs) were presented. A p-value less than 0.05 was considered statistically significant for all the estimates.

Results

Characteristics of the participants

Finally, 8211 participants were included in our whole study. A total of 8173 residents underwent the Spectralis OCT examination, of which 4 had unclear photos, so ultimately 8169 residents were included in this study. of 8173, 688 (8.42%, 95% CI 0.0782–0.0902) had ERM in at least one eye, and 413 (60.03%) were female, 418 (60.76%) were from urban area, 579 (84.16%) were from coastal region, 605 (87.9%) had any degree of education, and 423 (61.5%) had any level of income. (Table 1).

Table 1 The characteristics of the study participants and the prevalence of epiretinal membrane (n = 8173).
Full size table

ERM and associations with sociodemographic characteristics

In this study population, ERM (OR = 1.183, P = 0.039) was significantly correlated with urbanization. The percentage of ERM was significantly lower in the rural group than that in the urban group. ERM (OR = 1.516, P < 0.001) was also significantly associated with geographic location (coastal and inland) (OR = 1.516, P < 0.001). (Table 2).

Table 2 The logistic regression in epiretinal membrane with several research factors in Fujian Eye Study.
Full size table

In general, ERM was not significantly correlated with age (OR = 1.004, p = 0.354), sex (OR = 1.050, p = 0.552), educational background (OR = 1.081, p = 0.079), income (OR = 1.125, p = 0.104), smoking (OR = 0.956, p = 0.692) , alcohol consumption (OR = 1.049, p = 0.678) and tea consumption (OR = 1.033, p = 0.718). (Table 2).

Correlation of ERM with refractive error and IOP

In the whole study population, ERM was not significantly correlated with spherical equivalent (SE) (OR = 0.993, p = 0.644) and IOP (OR = 1.006, p = 0.579). (Table 2).

Multiple logistic regression

The multiple logistic regression demonstrated that the prevalence of ERM was correlated with coastal geographic location (OR = 1.540, p < 0.001) and the degree of urbanization (OR = 1.210, p = 0.020).

Discussion

The epidemiology of ERM initially primarily originated from population-based studies using non dilated retina photography and subsequent research combined the use of OCT. Our study used spectralis OCT to increase the sensitivity and reliability of detection, spectralis OCT was imported to China in 2014 and we was one of the first that multicolor OCT has been used for epidemiological investigations in China.

At present, the research baseline on the prevalence and related factors of ERM was not uniform, and great variability in the reported prevalence of ERM among different races and countries made comparison difficult. A review showed the prevalence of ERM was 7% to 11.8%, with increasing age being the most important risk factor, and gender did not appear to be a major risk factor3. While another review and meta analysis showed that only greater age and female significantly conferred a higher risk of ERMs8. A study showed a very high prevalence of 34% for epiretinal membranes in a cohort of the elderly (63–102 years) in the United States9. A French population-based follow-up study of 3 times (every two years) showed that the incidence rate of ERM was 9.42%10. While in China, the Jiangning Eye Study reported the prevalence of epiretinal membrane was 8.4% in residents aged 50 years and older11, which was similar with our study result (8.42%). A Population-Based Cohort Study of Older Adults in UK found that the prevalence of ERM was 7.6% (CI, 7.0%-8.3%). ERM was present more often in more myopic eyes, associated with an increase in levels of high-density lipoprotein (HDL) cholesterol and triglycerides12. Our study showed ERM was only associated with urbanization and geographic location.

The level of urbanization is one of the important factors affecting the incidence of ERM. Our study found that in areas with higher levels of urbanization, the incidence of ERM is also correspondingly higher. This may be related to factors such as lifestyle changes and increased work pressure brought about by urbanization. With the acceleration of urbanization, people’s lifestyles, dietary habits, and work environments have undergone significant changes. For example, a study conducted in Beixinjing area of Shanghai found that the prevalence rate of ERM was 1.02%, and it was significantly related to diabetes and higher education level13. This indicates that people in the highly urbanized areas receive better education and medical services, but may also increase the risk of some chronic diseases (such as diabetes) due to changes in lifestyle (such as reduced eating habits and physical activity), thus affecting the prevalence of ERM. On the one hand, adverse factors such as environmental pollution brought about by urbanization may cause damage to the eyes. A review on the effects of air pollution on the eye showed that air pollution not only affects the surface of the eye, but may also lead to more serious eye diseases such as glaucoma, cataracts, and age-related macular degeneration, and indoor pollution (such as environmental tobacco smoke, smoke from heating and cooking) is also associated with various eye diseases14; On the other hand, urbanization has also brought more medical resources and popularization of health knowledge, making it easier for people to access eye disease diagnosis and treatment15,16,17,18,19.

In addition to the level of urbanization, residential geographic location is also an important factor affecting the incidence of ERM. Fujian Province has a complex terrain and diverse climate, 80% are mountainous areas and 5 out of 9 cities are coastal, and environmental factors in different regions may have different impacts on the eyes20,21,22,23,24. Our study found that in some specific areas of Fujian, such as coastal areas, the incidence of ERM is significantly higher than that in other areas. This may be related to factors such as climate, environment, and dietary habits in these regions. For example, in coastal areas, ultraviolet radiation is strong, the climate is humid and the salt content in the air is high, which may cause certain irritation to the eyes. Recently, the impact of environmental factors on eye health has received increasing attention. And several reviews showed that the dietary patterns may affect on the incidence and progression of age-related eye diseases, namely age-related macular degeneration (AMD), cataracts, diabetic retinopathy (DR), and glaucoma25,26,27,28,29,30. Consumption of fruits, vegetables, fish, and olive oil, named the Mediterranean diet may be correlated with a lower risk of DR30. More than half of the cities in Fujian are coastal areas, where people tend to consume seafood in their diet, while our study found that the prevalence of ERM among coastal residents was higher than that among inland residents. This may indicate that the influence of social environmental factors is greater than that of geographical location. And the impact of these social environmental factors needs to be validated through basic experiments in the future.

Above all, the FJES team has discovered that the prevalence of ERM in Fujian province stands at 8.42%, significantly higher than the national average. Moreover, the risk factors for this condition are closely related to the degree of urbanization and coastal geographical location of residence. This study provides good data support for the future application of colorful OCT in ophthalmic epidemiological investigations. It can not only save time and cost in flow cytometry, but also provide more accurate information on the macular area, providing better assistance for disease diagnosis. In the future, we will continue to delve deeper into the mechanisms and associated risk factors of ERM, aiming to discover more effective prevention and treatment measures. We also call for greater attention and emphasis from all sectors of society towards eye diseases, contributing jointly to the advancement of human eye health.