A study recently published in Optometry and Vision Science performed a meta-analysis to identify key risk factors leading to primary angle-closure glaucoma (PACG), with the potential to lead to earlier diagnoses and more effective treatment.
Give me some background first.
Around half of glaucoma-related blindness is caused by PACG. Additionally, the risk of acute visual impairment is higher with PACG compared to primary open-angle glaucoma.
Previous studies have confirmed major risk factors that lead to PACG, including:
- Intraocular pressure (IOP)
- Anterior chamber depth (ACD)
- Axial length (AL)
- Age
- Sex
- Ethnicity
This study looked into further possible factors that have previously been unclear.
Now this research.
Researchers gathered past cross-sectional, case-control, and cohort studies from PubMed, Web of Science, and Embase databases using keyword search. See their complete search strategy here.
Out of an initial 69,309 results, 45 studies remained after elimination. See the characteristics of the final 45 selected studies here.
Ultimately, 30 articles were utilized for meta-analysis in the interest of each study’s results being repeatedly reported.
Now talk about the methods.
The investigators recorded key elements and factors from each eligible study; meta-analysis was then performed statistically with Stata software (Version 16) to look at each individual risk factor.
The quality of each study was assessed using the Newcastle-Ottawa Scale for case-control and cohort studies, as well as the Agency for Healthcare Research and Quality scale for cross-sectional studies.
And the findings?
The researchers selected a total of 29 factors associated with PACG that were repeatedly reported. A number of these were statistically significant across studies, shown as follows.
Previously reported factors that were further confirmed:
- IOP
- ACD
- AL
- Lens thickness
- Spherical equivalent
New factors determined through meta-analysis:
- Retinal nerve fiber layer (RNFL) thickness
- Body weight
- Cataract
- Hyperlipidemia
- Total cholesterol
- Triglyceride
- Malondialdehyde
- Short-term antidepressant exposure
So what does this mean?
With both hyperlipidemia and increased levels of triglyceride being significant, the researchers stated that this could suggest that lipid metabolism disorders influence PACG.
Regarding comorbidities, according to the authors, “Cataract might be involved in the pathogenesis of primary angle-closure glaucoma by affecting lens thickness.”
Go on…
The authors noted the changes in retinal nerve fiber layer have been shown in the early stages of PACG—thus displaying a key consistency.
Further, the researchers noted that mydriasis and cycloplegia resulting from antidepressant use “could exacerbate the closure of iridocorneal angle in patients with shallow anterior chambers and narrow chamber angles,” putting them at a higher risk for PACG.
Limitations?
This meta-analysis was limited to the pre-existing articles it had to draw from in this study. As a result, many potential risk factors remain unverified.
Additionally, the data was pulled from a small number of studies, and there were no adjustments made for potentially confounding variables.
Expert opinion?
Per the study authors, “More studies with larger numbers of cases and of high quality are warranted to validate the causal relationships between these factors and primary angle-closed glaucoma.”
They maintained that determining new risk factors can be incredibly helpful in identifying high-risk populations, but that applying these factors to clinical settings will likely remain a challenge.
Take home.
The data sheds light on possible novel risk factors associated with PACG, including lifestyle, serological, medication usage, comorbidity, and ophthalmic indicators.
While further research is necessary to fully validate the relationships between PACG and these factors, the findings represent a meaningful step to future research and discovery.