Findings from a retrospective observational study published in BMC Ophthalmology found that central retinal artery occlusion (CRAO) carries higher peripheral leukocyte and lymphocyte levels than branch retinal artery occlusion (BRAO).
The authors argued that the two subtypes are immunologically distinct entities that may benefit from different evaluation and management strategies.
Give me some background first.
Retinal artery occlusion (RAO) is an ophthalmic emergency and a red flag for systemic vascular disease, with CRAO carrying elevated short-term risk for stroke and acute myocardial infarction.
Worth noting: Inflammation is accepted as a key driver of RAO pathogenesis, but how that inflammation differs between CRAO and its BRAO counterpart has stayed murky.
Prior work flagged the neutrophil-to-lymphocyte ratio (NLR) as a useful biomarker in RAO, yet subtype-specific profiles were not well characterized.
Now, talk about the study.
A team at Renmin Hospital of Wuhan University ran a retrospective observational study to compare peripheral inflammatory biomarker profiles between CRAO and BRAO patients.
The question: Do the two RAO subtypes show different systemic inflammatory patterns—and could that change how we evaluate each one?
Who was included in the study?
Investigators reviewed medical records from 363 patients diagnosed with RAO between January 2020 and April 2024.
The breakdown: 320 CRAO patients and 43 BRAO patients.
Demographics: Average age was 57.7 years in the CRAO group versus 55.3 years in the BRAO group. Men made up 69% of CRAO cases and 63% of BRAO cases.
- Rates of systemic disease stayed comparable across groups, but current smoking was reported in 31% of CRAO cases versus 16% of BRAO, and alcohol consumption was more common in the CRAO cohort at 20.3% versus 11.6%.
- Patients with active infections, malignancies, or severe hepatic or renal dysfunction were excluded.
Findings?
CRAO patients showed higher leukocyte counts than BRAO: 6.57 ± 2.19 vs. 5.95 ± 1.66 × 10⁹/L (p = 0.03).
Lymphocyte percentages ran higher in CRAO as well: 30.75 ± 8.62% vs. 27.32 ± 7.52% (p = 0.01).
However: Neutrophil percentages went the other way. CRAO patients had lower neutrophil percentages (58.33 ± 9.08% vs. 61.92 ± 8.07%, p = 0.01), despite having higher overall white counts.
Worth noting: Monocyte and eosinophil percentages did not differ meaningfully between groups, and the between-group shifts were modest in absolute terms. Group-level means largely stayed within conventional reference ranges.
Tell me more.
With CRP: C-reactive protein (CRP) levels did not differ significantly between groups, though the CRAO group showed greater variability.
And with NLR: In patients with available absolute counts, BRAO demonstrated a higher neutrophil-to-lymphocyte ratio than CRAO, which the authors noted is consistent with a more localized, neutrophil-predominant inflammatory response.
- Subgroup analyses held up across sex and age, with more pronounced neutrophil-lymphocyte shifts in males and steeper age-related changes in CRAO.
Bring it all together for me.
CRAO may behave more like a systemic vascular/inflammatory event (stroke equivalent) and BRAO may be more of a localized microvascular insult. While both require systemic evaluation, this might mean we risk-stratify BRAO patients differently.
Any limitations?
A few …
- The study’s single-center, retrospective design
- The BRAO arm was small (n = 43) relative to CRAO (n = 320), which limited statistical power for subgroup comparisons.
- Lab panels reflected a single timepoint at initial presentation, with no prospective validation or healthy control comparator
Expert opinion?
No outside expert commentary was included in the study.
Their position: The authors argued that the findings support treating CRAO and BRAO as immunologically distinct entities, and that subtype-specific evaluation and management strategies may be warranted.
The broader systemic inflammatory footprint in CRAO, versus the more localized neutrophil predominance seen in BRAO, reinforced that case.
Take home.
For clinicians working up an acute RAO, the subtype matters.
CRAO appears to carry a broader systemic inflammatory signal, while BRAO trends toward localized neutrophil predominance and a higher NLR.
As such: Routine peripheral blood work at presentation may offer useful clinical context beyond a single label of "retinal artery occlusion," especially when triaging for downstream vascular workup.