Abstract:

Objective

To explore the association between fundus retinal characteristics and the prevalence of cardiovascular and cerebrovascular diseases through screening in extremely high-altitude regions（Tibet Autonomous Region）.

Methods

A total of 2 712 Tibetan residents living permanently at high altitude（4 500 metres above sea level） across 51 villages in 8 townships of 3 counties （Nyima， Shuanghu， and Amdo counties） in Nagchu region of the Tibet Autonomous Region were included as the study population.Data from 1 919 301 health checkups conducted in lower altitude areas were used as a control group.Fundus photographs of the study population under the natural pupil conditions were coptured using the Canon Dilution-Free Fundus Camera CR-2AF from Japan， and key structural features， such as age-related macular degeneration （AMD）， cup-to-disc ratio， similar manifestations of diabetic retinopathy， retinal vein occlusion，anterior optic disc， and other anomalies were recorded in detail.

Results

（1） No statistically significant difference in the incidence of AMD was found between extremely high-altitude areas and plain areas populations across different age groups （P＞0.05）； （2） Within the extremely high-altitude areas， individuals aged 20-29 had the highest incidence of enlarged cup-to-disc ratio compared to other age groups， with a statistically significant difference （χ^²=60.502， P＜0.001）.Comparatively， the 30-39 age group in extremely high-altitude areas had a higher incidence of enlarged cup-to-disc ratio than the plain areas group， with a statistically significant difference （χ^²=230.325， P＜0.001）； （3） The incidence rates of diabetic retinopathylike manifestations in the 30-39 and 40-49 age groups showed statistically significant differences （χ^²=5.390，P=0.020； χ^²=8.830， P=0.003）； （4） No statistically significant differences in the incidence rates of vein occlusion were observed between the two groups in the 30-39， 40-49 age groups （χ^²=0.071， P=0.190； χ^²=0.853，P=0.356）， but a statistically significant difference was found in the 50-59 and over-60 age group （χ^²=10.400，P＜0.001； χ^²=31.848， P＜0.001）； （5） Statistically significant differences in the incidence rates of anterior optic disc were found between the two groups in the 30-39 age groups （χ^²=3.850， P=0.016）； （6） Statistically significant differences in the incidence rates of other macular abnormalities were found between the two groups in the 50-59 and over-60 age groups （χ^²=5.080， P=0.024； χ^²=10.500， P=0.001）.

Conclusion

There are notable differences in the spectrum of fundus photographic characteristics between populations in extremely highaltitude areas and those in low-altitude regions.

Key words: High-altitude cardiovascular and cerebrovascular disease, Fundus characteristic spectrum, Tibetans in the Tibet Autonomous Region, Fundus retina, Fundus photography