Haroen Sahak1, Saeed Azizi2, Adnaan Haq3
1FY2 doctor, NHS Frimley Health Foundation Trust
2Ophthalmology Registrar, Royal Free Hospital NHS Foundation Trust
3Ophthalmology Registrar, Moorfields Eye Hospital
Background
Sickle cell disease (SCD) is an autosomal recessive disease that causes abnormally shaped haemoglobin molecules resulting in a sickle shaped red blood cell. SCD is associated with significant microvascular and macrovascular comorbidities. If untreated, SCD has significant mortality (1).
Epidemiology
SCD is most common in sub-Saharan Africa, India, the Middle East and the Mediterranean (2). However, recent migration from high prevalence areas increased the incidence of SCD in Europe (2). In England, there are between 12,000 to 15,000 individuals diagnosed with SCD, this is increasing every year (2,3). As a result, SCD now poses a significant health burden in England.
Impact on public health
The treatment of SCD has improved in recent years and patients are living longer. But this has resulted in an increase of complications of the eye that were previously quite rare (2). Heterozygous SCD (HbSC) has fewer systemic complications but is more likely to cause ocular problems (2). Hence, all patients with SCD need close monitoring by ophthalmologists to prevent loss of vision. Especially, since the onset of sickle cell retinopathy can develop insidiously.
Pathophysiology
SCD commonly causes visual problems. It can affect all parts of the eye, as the abnormally shaped blood cells can occlude of any small vessel in the body. The crescent shaped red blood cells affect the oxygen carrying ability of blood. Therefore, SCD affects all major organs such as the spleen, lungs, heart, kidneys, liver and eyes. As a consequence, patients with SCD can suffer from a widespread of serious pathologies such as: chronic anaemia, stroke, chest pain, tissue necrosis, shortness of breath, kidney damage, recurrent infections and painful sickle cell crises.
Symptoms & Signs
Most patients surprisingly reported good visual acuity and are asymptomatic. SCD can affect both the anterior and posterior chamber of the eye. Anterior manifestations: cataracts, iris atrophy and orbital wall infarction. Posterior manifestations: optic neuropathy secondary to glaucoma, non-proliferative and proliferative retinopathy, maculopathy, vitreous haemorrhage and retinal detachment (4).
Patients may experience flashes and floater, loss of visual acuity, red eye, blurred vision or painful eye (5). Therefore, ophthalmic examination is vital to detect common signs of eye disease such as: neovascularization, evidence of proliferative and non-proliferative retinopathy, maculopathy, retinal artery, salmon patch occlusion and venous tortuosity (6).
Investigations
After the age of 10, yearly eye examinations are recommended, which may include optical coherence tomography (OCT) angiography and spectral domain OCT (7).
Treatment
Early treatment for sickle cell eye disease is vital in order to prevent blindness. There are various treatments available for SCD. Systemic treatment such as hydroxycarbamide increases foetal haemoglobin (HbF) which prevents occlusion crises (8). This has a therapeutic effect not just on the eye but systemically. Laser and anti-VEGF treatments are used to treat microvascular haemorrhages and neovascularization (9). Ophthalmic surgery is indicated in severe tractional retinal detachment or non-resolving dense vitreous haemorrhage (8).
Conclusion
SCD affects mainly patients from a low socioeconomic group and ocular manifestations are present in more than 40% of asymptomatic patients (10). Furthermore, patients with SCD have been stigmatised and neglected frequently by the health service for being ‘drug seekers’ and have died as a result of poor medical practice. Therefore, it is important to take SCD serious and ensure patients are treated and followed up promptly from an early age to prevent ocular and systemic complications.
References
1. Weatherall DJ, Clegg JB, (2001). Inherited haemoglobin disorders: An increasing global health problem. Bull World Health Organ ;79(8):704–12.
2. Sickle cell eye disease (2018). AOP ;1–13. [Online]. Available from: https://www.aop.org.uk/ot/cet/2017/03/13/sickle-cell-eye-disease/article. (Accessed 03/11/2018)
3. Dormandy E, James J, Inusa B, et al. (2018). How many people have sickle cell disease in the UK? J Public Health (Oxf) ;40(3):e291–5.
4. Osafo-Kwaako A, Kimani K, Ilako D, Akafo S, Ekem I, Rodrigues O, Enweronu-Laryea C, Nentwich MM. Ocular manifestations of sickle cell disease at the Korle-bu Hospital, Accra, Ghana. Eur J Ophthalmol. 2011 Jul-Aug;21(4):484-9. doi: 10.5301/EJO.2010.5977. PMID: 21058274.
5. Bakri S, Berrocal A, Capone A, Choudhry N, et al. Sickle Cell Retinopathy. The American Society of Retina Specialists. [Online] . Available from: https://www.asrs.org/patients/retinal-diseases/41/sickle-cell-retinopathy
6. Duan XJ, Lanzkron S, Linz MO, et al. (2018). Clinical and ophthalmic factors associated with the severity of sickle cell retinopathy. Am J Ophthalmol [Internet]. Elsevier Inc.;Available from: https://linkinghub.elsevier.com/retrieve/pii/S0002939418305531
7. Mathew R, Bafiq R, Ramu J, et al. (2015). Spectral domain optical coherence tomography in patients with sickle cell disease. Br J Ophthalmol ;99(7):967–72.
8. Sickle Cell Disease and the Eyes (2018). [Online]. Available from: https://sicklecellanemianews.com/sickle-cell-anemia-and-the-eyes
9. Saif Aldeen AlRyalat, Mohammed Nawaiseh, Barakat Aladwan, Allaa Roto, Zeyad Alessa & Akram Al-Omar (2020): Ocular Manifestations of Sickle Cell Disease: Signs, Symptoms and Complications, Ophthalmic Epidemiology, DOI: 10.1080/09286586.2020.1723114
10. Dell’Arti L, Barteselli G, Riva L et al. (2018) Sickle cell maculopathy: Identification of systemic risk factors, and microstructural analysis of individual retinal layers of the macula. PLoS One ;13(3):1–17.