Sickle Cell Retinopathy


Sickle cell disease:

  • Normal HbA = 2 alpha-globin + 2 beta-globin + central haem molecule.
  • Point mutation at the 6th position of chromosome 11 –> replacement of glutamic acid by a valine in beta-globin of Hb –> HbS.
  • Autosomal recessive.
  • Both genes are sickle cell variant = SS disease.
  • When one gene has HbC variant = SC disease (less severe form).
  • When one gene is normal –> no disease = SC trait (carrier).
  • Associated with beta-thalassemia gene.
  • Afro-American / Hispanic – 0.15% sickle cell disease overall.
  • Black Americans – 8% SC trait.

Ophthalmic manifestations:

  1. Orbital – orbital bone infarction ; orbital haematoma (need Abx + steroid Rx or orbital decompression) ; lacrimal gland swelling.
  2. Anterior segment – Paton’s conjunctival sign (corkscrew saccular dilation of conjunctival vessels) ; radial iris neovascularisation (–> NVG) ; hyphaema (EMERGENCY – risk CRAO even with mild IOP rise – need AC washout or paracentesis)
  3. Retinal changes

Retinal changes:

  • Non-proliferative sickle retinopathy:
  • 1) Salmon-patch haemorrhages (result of sudden giving way of occluded vessel)
  • 2) Black sunburst (localised choroidal ischaemic damage of RPE –> localised CNVM or subretinal tracking of retinal haemorrhage)
  • 3) Peripheral retinal whitening with strong vitreoretinal adhesion – like white without pressure (common).
  • 4) Macular iscahmeia – enlarged FAZ.
  • 5) Rarely – macular hole, ERM, foveoschisis, CNVM
  • Proliferative sickle retinopathy:
  • Staging by Goldberg (1971):
  • Stage I – peripheral vascular occlusion with silver wiring of arterioles at temporal retina.
  • Stage II – AV anastomosis – non-leaking
  • Stage III – sea fan neovascularisation (commonly superotemporal)
  • Stage IV – Vitreous haemorrhage
  • Stage V – Tractional retinal detachment
  • Commonly SC disease patient & HbS-beta thalassaemia.

Investigations: Ultrawide field angiography ; OCT macula

Management:

  • Non-proliferative cases: observe 3-6 months.
  • Proliferative cases: observe (1/3 regress with autoinfarction)
  • Proliferative cases with bilateral disease, rapid Stage III onwards progression: targeted laser treatment of ischaemic areas.
  • Vitreous haemorrhage without RD: Observe.
  • Vitreous haemorrhage with RD: PPV + endolaser +/- preop anti-VEGF.
  • Scleral buckle – use with caution due to risk of anterior segment ischaemia.

References:


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Location Birmingham Midlands Eye Centre 76 Dudley Road Birmingham B18 7QH UK Phone 0121 554 3801 Hours Mr Ch'ng | Vitreoretinal Clinic Sessions: Monday: 8.30am - 12.30pm Wednesday (alternate): 8.30am - 5.00pm Thursday: 8.30am - 12.30pm Friday: 8.30am - 12.30pm | Vitreoretinal Theatre Sessions: Wednesday (alternate): 8.30am - 5.00pm & Friday (emergency cases): 1.30pm - 5.00pm | Eye Casualty Session: Monday 1.00pm - 4.30pm |
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