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PurposeTo test the reliability and accuracy of a standardised non-invasive imaging algorithm using optical coherence tomography angiography (OCTA) in detecting and quantifying pharmacologically induced changes in the perilimbal vasculature.MethodsIn this prospective observational imaging study, 370 angiograms of 15 normal eyes and 10 eyes with nasal pterygiums were obtained using a commercially available OCTA system with split-spectrum amplitude-decorrelation angiography technology. Postprocessing of the images to quantify the area occupied by the blood vessels was performed using the Fiji software. The main outcome measures were reliability (intraobserver and interobserver agreement) and accuracy of the standardised algorithm in detecting and quantifying relative change (vasoconstriction and vasodilatation) in the area occupied by the blood vessels after instillation of topical vasoconstrictors.ResultsThe intraclass correlation coefficients for intraobserver and interobserver agreement were 0.91 and 0.88 (good to excellent), respectively. In normal eyes, significant vasoconstriction was noted at 5 min (35%–47%) after application of eye-drops, which peaked at 10 min (43%–63%) and was sustained until 20 min (35%–51%), followed by gradual recovery. Greatest effect was noted with a combination of 5% phenylephrine and 0.15% brimonidine tartrate (BT) eye-drops as compared with either one or two drops of BT alone, both at the 10 min (p=0.0058) and 20 min (p=0.0375) time points. This dose-dependent temporal trend was replicated in eyes with primary nasal pterygium (p=0.31).ConclusionsThe findings suggest that OCTA can reliably and accurately detect and quantify relative changes in the perilimbal vasculature in both normal eyes and in eyes with pterygium.

A 19-year-old girl presented with severe pain and redness in her right eye and also with nasal congestion and epistaxis since the past 5 months. The patient was systemically investigated and tested positive for proteinase 3 anti-neutrophil cytoplasmic antibody (PR-3 ANCA) with raised erythrocyte sedimentation rate (ESR). The provisional diagnosis of granulomatosis with polyangiitis (GPA) was made, and she was started on systemic steroids and azathioprine after consultation with the rheumatologist. However on steroid taper, she developed severe reactivation of the scleritis and the corneal involvement was noted in the form of peripheral ulcerative keratitis. Instead of starting another course of high dose oral cortico-steroids or pulse cyclophosphomide, she was started on rituximab infusion (two doses), and oral methotrexate was added, leading to the successful remission of the disease.

This article has been peer reviewed and published immediately upon acceptance. It is an open access article, which means that it can be downloaded, printed, and distributed freely, provided the work is properly cited. Articles in "Folia Morphologica" are listed in PubMed.

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