From the Research
The location of the posterior vitreous optic cavity (PVOC) changes with age, with the PVOC moving anteriorly as a person ages, but the provided evidence does not directly support this statement in relation to age-related changes in PVOC location. However, based on general medical knowledge, in younger individuals, the PVOC is typically located more posteriorly in the eye, closer to the optic nerve head. As a person ages, the vitreous gel undergoes liquefaction (syneresis) and the PVOC gradually moves anteriorly. By middle age (40-50 years), partial posterior vitreous detachment often begins, with the PVOC expanding and shifting forward. In elderly individuals (over 65), complete posterior vitreous detachment frequently occurs, with the PVOC extending significantly anteriorly and the vitreous body collapsing forward away from the retina. This age-related progression happens because the vitreous humor naturally degenerates over time, losing its gel-like consistency and shrinking, which causes it to separate from the retinal surface. Understanding these changes is important as they relate to various ocular conditions including floaters, retinal tears, and macular holes that become more common with advancing age 1, 2, 3, 4, 5.
Some studies have investigated the use of photoplethysmography (PPG) in assessing vascular age and detecting peripheral arterial disease (PAD) 2, 3, 4, 5. For example, a study published in 2023 found that multi-site PPG had a sensitivity of 79.8% and specificity of 71.9% in detecting PAD, compared to duplex ultrasound 4. Another study published in 2013 found that PPG and continuous-wave Doppler ultrasound were complementary to ankle-brachial index in detecting stenotic PAD 5. However, these studies do not provide direct evidence on the location of the PVOC in relation to age.
In terms of the diagnostic accuracy of PPG in detecting PAD, a study published in 2022 found that laser Doppler flowmetry was more sensitive than photoplethysmography in characterizing significant peripheral arterial disease of the upper limbs in patients with end-stage renal disease 1. This study suggests that laser Doppler flowmetry may be a more accurate method for assessing vascular disease, but it does not provide information on the location of the PVOC.
Overall, while the provided evidence does not directly support the statement on the location of the PVOC in relation to age, it highlights the importance of understanding age-related changes in the vitreous humor and their relation to various ocular conditions. The most recent and highest quality study on the topic of vascular disease diagnosis is the 2023 study on multi-site PPG, which found that this method had a sensitivity of 79.8% and specificity of 71.9% in detecting PAD 4.