Neovascularisation and Retinal Vein Occlusion

Overview

Retinal vein occlusions can lead to an increase in intraluminal venous pressure which causes capillary endothelial cell damage and capillary dropout. The resultant ischaemia causes an upregulation of vascular endothelial growth factor (VEGF) which stimulates the development of new vessels (neovascularisation). These new vessels may be found at the disc (NVD), elsewhere in the retina (NVE) and/or on the iris (NVI). A major factor in the development of neovascularisation in retinal vein occlusions is the severity and extent of retinal ischaemia.

Retinal neovascularisation first develops within the retina but can breach the internal limiting membrane (ILM) and progress into the vitreous cavity. On OCT imaging, hyper-reflective lesions can be seen on the retinal surface and may attach to the posterior hyaloid. OCT-angiography can be used to confirm the presence of neovascularisation by showing a hyper-reflective network within the vitreoretinal interface.

In BRVO, the major site of neovascularisation is the retina or at the optic disc while CRVO have a higher risk of iris neovascularisation and subsequent neovascular glaucoma. The majority of neovascular glaucoma presents within 3 months of the initial event and is sometimes refer '90-day glaucoma'.

Ocular neovascularisation is the most common within the first 6-12 months following a retinal vein occlusion, however it can occur up to 3 years after. Therefore, regular comprehensive assessments are required for all cases of retinal vein occlusions. This should include slit lamp examination and gonioscopy to detect neovascularisation of the iris and/or angle, as well as dilated fundus examinations.

Rubeosis Irides

  • Case 1

    A 75 year old Caucasian female. Intraocular pressures are 12mmHg in the right eye and 48mmHg in the left. The vision in her left eye is light perception only.

    Anterior eye photo (left eye)

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    Anterior eye photo (left eye)

    Anterior eye photography shows fine network of vessels on the iris surface, predominantly around the pupil border extending towards the midperipheral iris and towards the anterior chamber angle. All patients with iris neovascularisation require gonioscopy to be performed to exclude involvement of the angle.

    Anterior eye photo (left eye)

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    Anterior eye photo (left eye)

    Anterior eye photography shows fine network of vessels on the iris surface, predominantly around the pupil border extending towards the midperipheral iris and towards the anterior chamber angle. All patients with iris neovascularisation require gonioscopy to be performed to exclude involvement of the angle.

  • Case 2

    A 75 year old Asian male. Vision in the right eye recorded as no light perception. He reports that the eye has been blind for a few years.

    Anterior eye photo (right eye)

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    Anterior eye photo (right eye)

    Anterior eye photography of the right eye shows iris neovascularisation, prominent fibrosis obscuring the pupil and corneal stromal neovascularisation.

    Anterior eye photo (right eye)

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    Anterior eye photo (right eye)

    Anterior eye photography of the right eye shows iris neovascularisation, prominent fibrosis obscuring the pupil and corneal stromal neovascularisation.

Retinal Neovascularisation

  • Case 1

    A 62 year old Asian male with a history of BRVO in his right eye that was treated with panretinal laser photocoagulation 6 years ago. The best corrected visual acuity is 6/4.8 (20/15) in the right eye.

    Fundus photograph and red-free image (right eye)

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    Fundus photograph and red-free image (right eye)

    Fundus photography shows well defined regions of chorioretinal atrophyin the superotemporal retina of the right eye, consistent with the history of panretinal laser photocoagulation (PRP). Vessel sheathing can also be seen within this area. There are no signs of neovascularisation at the disc.

    Additional findings include a superior RNFL defect and hypopigmentary changes at the macula.

    Optomap and green separation images (right eye)

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    Optomap and green separation images (right eye)

    Widefield imaging highlights the extensive PRP treatment that extends into the superotemporal peripheral retina. Vessel sheathing is better visualised on this image. There is also an area of dark without pressure in the superior midperiphery.

    Upon further investigation, blot haemorrhages and an irregular network of vessels can be seen at the inferior border of the treated zone (superotemporal to the macula).

    Fundus autofluorescence imaging (right eye)

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    Fundus autofluorescence imaging (right eye)

    Fundus autofluorescence imaging shows well defined regions of hypo-autofluorescence corresponding to the chorioretinal atrophy.

    Spectralis OCT volume scan (right supero-temporal retina)

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    Spectralis OCT volume scan (right supero-temporal retina)

    OCT imaging inferior to the PRP treatment zone shows hyper-reflective lesions anterior to the internal limiting membrane (ILM) with attachment to the posterior hyaloid of the vitreous. These lesions represent the proliferation of new vessels.

    OCT imaging through the superior treatment zone shows chorioretinal atrophy.

    Spectralis OCT line scans through area of neovascularisation

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    Spectralis OCT line scans through area of neovascularisation

    OCT imaging inferior to the PRP treatment zone shows hyper-reflective lesions anterior to the internal limiting membrane (ILM) with attachment to the posterior hyaloid of the vitreous. These lesions represent the proliferation of new vessels.

    OCT Angiography through area of neovascularisation

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    OCT Angiography through area of neovascularisation

    OCT-angiography shows the presence of blood flow within these irregular vessels, consistent with retinal neovascularisation. Note the capillary non-perfusion in the surrounding retina , which promotes the development of new vessels.

Differential Diagnosis

Proliferative diabetic retinopathy

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Collateral vessels

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References

Khayat, Survey Ophth 2018. Major Review: Ischemic retinal vein occlusion: characterising the more severe spectrum of retinal vein occlusion

Patel, A., Nguyen, C., & Lu, S. (2016). Central Retinal Vein Occlusion: A Review of Current Evidence-based Treatment Options. Middle East African journal of ophthalmology, 23(1), 44–48.

Sohan Singh Hayreh, Patricio Rojas, Patricia Podhajsky, Paul Montague, Robert F. Woolson (1983) Ocular Neovascularization with Retinal Vascular Occlusion-III: Incidence of Ocular Neovascularization with Retinal Vein Occlusion, Ophthalmology, Volume 90, Issue 5.