What was the purpose of the study?
In recent years, we have seen a rise in myopia globally, particularly among younger populations. This growth has prompted studies on the potential long-term impacts of myopia, such as changes in the retina and associated vascular structures.
Myopia progression can result in more severe eye health issues, such as macular degeneration and retinal detachment. In our study, we aimed to investigate how myopia affects the retina, specifically looking at vessel density, macula thickness, and the foveal avascular zone (FAZ) in a young adult sample. By using advanced imaging technology like optical coherence tomography with angiography (OCT-A), we sought to gain a deeper understanding of the early changes in the eye that might signal worsening myopia.
The primary goal of our study was to explore how moderate myopia in young adults affects retinal structure and blood flow. We looked at three key areas: vessel density (VD), macula thickness (MT), and the size of the FAZ, a part of the eye that lacks blood vessels but is crucial for clear vision.
By focusing on these metrics, we hoped to gain insight into early signs of myopic damage to help us understand whether moderate myopia could lead to preclinical disruptions in retinal health, ultimately aiding early diagnosis and intervention strategies for patients at risk of severe myopic complications.
What did we find and what does this suggest?
Our study found that young adults with moderate myopia had significantly lower vessel density in both the superficial and deep layers of the retina, particularly in areas near the central fovea.
Additionally, the foveal avascular zone was smaller in myopic eyes compared to emmetropic eyes, which, at present may be considered inconclusive due to the pilot nature of our study. However, the vessel density findings suggests that myopia could reduce blood flow and cause thinning in certain parts of the retina.
Together, these findings suggest that moderate myopia may be linked to retinal vascular and structural changes in young adults. However, we did not find a clear relationship between the degree of myopia and these changes, indicating that more research is needed to fully understand how these factors interact over time.
The vascular system of the retina is essential for maintenance of normal visual function. A decrease in retinal microvasculature may cause the retina to become more vulnerable in pathological myopia. A reduction in vessel density and retinal thickness may lead to an unbalanced metabolic supply and retinal function abnormalities, which may eventually result in compromised visual function.
Importance to eye care professionals
The findings highlight the nuances of retinal changes in myopic patients. For eye care professionals, these findings emphasise the importance of early detection and monitoring of retinal changes in myopic patients. The reduced vessel density and retinal thickness may indicate a higher susceptibility to retinal issues down the road, so proactive monitoring using OCT could be beneficial. The reduction in retinal blood flow and thinning of the macula seen in our study could be early indicators of more serious eye health issues, such as myopic macular degeneration. Using tools like OCT-A can help optometrists and ophthalmologists keep a close surveillance on these changes and intervene early if necessary.
Essentially, this research provides a foundation for identifying early retinal disruptions before they develop into more serious conditions. This study underscores the importance of regular follow up for myopic patients, especially young adults whose eyes are still developing.
What were the study’s limitations, and what are the future directions?
This was a pilot study, so it provides preliminary data, but larger studies are needed to confirm these findings across different populations. We only included young adults, so it remains unclear whether these retinal changes are present in other age groups and magnitudes of myopia. Additionally, the study’s cross-sectional design only captures a snapshot in time, which limits our ability to assess the progression of changes.
Further work should aim to conduct a broader study that includes more participants to validate these initial findings. It would be particularly beneficial to examine the same individuals over time to understand how retinal changes evolve as myopia progresses.
Moreover, studies involving different ethnic groups could provide a more comprehensive picture of myopia’s impact on the retina. Considering that the inner retinal thickness was reduced, it is also recommended that a closer inspection of the retinal layers (including the ganglion cell layer thickness) at the fovea may help isolate local inner retinal disruptions contributing to the deterioration in global thickness.
Examining sub-foveal choroidal thickness in African myopes maybe be valuable given the absence of this association. Establishing such associations may serve as harbingers of retinal deterioration for myopia in general, which might be extended to a multi-ethnic population study.
Conclusion
In summary, our pilot study suggests that myopia in young adults is associated with reduced retinal blood flow and thinning of the retina. As myopia continues to rise globally, understanding how it affects the eye at a structural level is crucial for developing effective management strategies.
These findings underscore the importance of OCT in monitoring myopic patients, allowing for early intervention before more severe retinal complications develop. Developing a standardised approach for monitoring vessel density and retinal thickness using OCT will also be key in translating this research into practical, clinical recommendations.
- Alvin Munsamy is an associate professor of optometry at the School of Health Sciences at the University of KwaZulu-Natal (UKZN), South Africa. He is a nationally rated scientist in clinical optometry, awarded this recognition by the National Research Foundation and the Department of Science and Innovation (South Africa).
- Additionally, he serves as the editor-in-chief of the journal African Vision and Eye Health and is a board examiner for the Professional Board for Optometry and Dispensing Opticians (Health Professions Council South Africa). Lehlomela Monthati, Mlambo Minenhle, Mngomezulu Zwelakhe, Ndlovu Nokubongwa and Radebe Mthobisi were honours students in optometry at UKZN during the study and are now practicing clinicians across South Africa.
Full findings were published in:
Munsamy AJ, Monthati L, Minenhle M, et al. Vessel density, macula thickness, and foveal avascular zone measurements in young African adults with moderate myopia: A pilot study. Ophthalmic and Physiological Optics. 2024. Link to article: https://doi.org/10.1111/opo.13385
