Association of Change in Iris Vessel Density in Optical Coherence Tomography Angiography With Anterior Segment Ischemia After Strabismus Surgery

PurposeTo compare anterior segment optical coherence tomography angiography (AS-OCTA) systems in delineating normal iris vessels and iris neovascularisation (NVI) in eyes with pigmented irides.MethodsProspective study from January 2019 to June 2019 of 10 consecutive patients with normal pigmented iris, had AS-OCTA scans with a described illumination technique, before using the same protocol in five eyes with NVI (clinical stages 1–3). All scans were sequentially performed using a spectral-domain OCTA (SD-OCTA), and a swept-source OCTA (SS-OCTA, Plex Elite 9000). Images were graded by two masked observers for visibility, artefacts and NVI characteristics. The main outcome measure was iris vessel density measurements comparing SS-OCTA and SD-OCTA systems.ResultsThe median age of subjects was 28 (20–35) years, and 50% were female. The paired mean difference of iris vessel density measurements was 11.7 (95% CI 14.7 to 8.1; p=0.002), SS-OCTA detecting more vessels than SD-OCTA. The inter-rater reliability for artefact score (κ=0.799, p<0.001) and visibility score (κ=0.722; p<0.001) were substantial. Both AS-OCTA systems were able to detect NVI vessels with a fair agreement (κ=0.588), with clearer NVI characteristics in stage 1/2 compared to stage 3 NVI (mean difference NVI score: 2.7±0.4, p=0.009).ConclusionThe SS-OCTA was better able to delineate iris vessels in normal pigmented irides compared to SD-OCTA. Both AS-OCTA systems identified NVI characteristics based on its atypical configuration or location, but further improvements are needed to allow for more accurate objective, serial quantification for clinical use.

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Role of anterior segment optical coherence tomography angiography in assessing limbal vasculature in acute chemical injury of the eye

British Journal of Ophthalmology ◽

10.1136/bjophthalmol-2021-318847 ◽

2021 ◽

pp. bjophthalmol-2021-318847

Author(s):

Marcus Ang ◽

Valencia Foo ◽

Mengyuan Ke ◽

Bingyao Tan ◽

Louis Tong ◽

...

Keyword(s):

Optical Coherence Tomography ◽

Optical Coherence Tomography Angiography ◽

Rapid Assessment ◽

Anterior Segment ◽

Vessel Density ◽

Optical Coherence ◽

Slit Lamp ◽

Swept Source ◽

Chemical Injury

PurposeTo study the role of two anterior segment optical coherence tomography angiography (AS-OCTA) systems in eyes with acute chemical injury.MethodsProspective study in subjects with unilateral chemical injuries. Sequential slit-lamp assessment with spectral domain (SD) (AngioVue, Optovue, USA) and swept source (SS) (Plex Elite, Zeiss, Carl Zeiss Meditec, Dublin, California, USA) AS-OCTA was performed in both eyes within 24–48 hours of injury. Subjects were managed with a standard clinical protocol and followed-up for 3 months. We assessed limbal disruption (loss of normal limbal vessel architecture), limbal vessel density measurements and agreement (kappa coefficient, κ) between masked assessors of limbal disruption based on AS-OCTA scans and slit-lamp assessment.ResultsTen subjects with median age 31 (25–33) years, 20% women, 60% suffered alkali injuries (Roper-Hall grade 1.5±0.7, Dua grade 2.3±1.2) at presentation. Mean limbal vessel density was lower in quadrants of affected eyes compared with controls detected by SD AS-OCTA (9.4%±2.0% vs 15.5%±1.8%, p<0.001) and SS AS-OCTA (8.8%±2.5% vs 13.9%±1.3%, p=0.01). There was substantial agreement when assessing limbal disruption on AS-OCTA (κ=0.7) compared with slit-lamp evaluation (κ=0.4). Overall, we found good agreement between SD and SS AS-OCTA systems in assessing limbal vessel density in eyes with chemical injury at presentation (mean paired difference: −1.08, 95% CI −3.2 to 0.5; p=0.189).ConclusionsIn this pilot study, AS-OCTA provided objective, non-contact, rapid assessment of limbal vasculature involvement in eyes with acute chemical injury. Further studies are required to establish the role of AS-OCTA in determining the prognosis of eyes with chemical injury.

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Comparison of anterior segment optical coherence tomography angiography systems for corneal vascularisation

British Journal of Ophthalmology ◽

10.1136/bjophthalmol-2017-311072 ◽

2017 ◽

Vol 102 (7) ◽

pp. 873-877 ◽

Cited By ~ 21

Author(s):

Marcus Ang ◽

Kavya Devarajan ◽

Suchandrima Das ◽

Tisha Stanzel ◽

Anna Tan ◽

...

Keyword(s):

Optical Coherence Tomography ◽

Image Quality ◽

Optical Coherence Tomography Angiography ◽

Anterior Segment ◽

Case Series ◽

Vessel Density ◽

Optical Coherence ◽

Cross Sectional ◽

Density Measurements ◽

Split Spectrum

AimTo newly describe a spectral-domain (SD) optical coherence tomography angiography (OCTA) for the cornea and directly compare two OCTA system scans of the same eyes with corneal vascularisation.MethodsCross-sectional, observational, comparative case series. We performed sequential OCTA scans (10 eyes of 10 subjects with corneal vascularisation,4 scans each eye) repeated using split-spectrum amplitude decorrelation algorithm angiography system (SSADA, AngioVue; Optovue Inc, USA) and SD OCTA (Angioscan; Nidek Co. Ltd, Japan) in the same region of interest. We analysed all scan images for repeatability, image quality and vessel density measurements and compared OCTA systems.ResultsWe obtained substantial interobserver repeatability in terms of image quality score (κ=0.86) for all 80 OCTA scans (median age 49 years, 50% women). The correlation was moderately good (r=0.721) when comparing vessel density measurements between OCTA systems, but greater in the SSADA compared with SD OCTA system (mean vessel density 20.3±4.9% vs 15.1±4.2%, respectively; p<0.001).ConclusionIn this pilot clinical study, we describe successful delineation of corneal vessels with substantial image quality using a new SD OCTA system. The vessel density measurements were greater using the SSADA compared with SD OCTA system in the same area of corneal vascularisation. Further studies are required to confirm the advantages, limitations and differences between these OCTA systems for the anterior segment.

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