Sickle retinopathy in patients with sickle trait

Abstract

SUMMARYSickle trait is the commonest of the sickle haemoglo binopathies and affects approximately 9% of the Afro-Caribbean population of North America. ] Traditionally the condition was considered to be benign, important only for its genetic implications, 2 , 3 but some authors have challenged this viewpoint. Spontaneous vitreous haemorrhage, 3 , 4 proliferative retinopathr and other ocular lesions have been described, albeit in the presence of some precipitat ing factor.Factors known to enhance sickling of red blood cells, thereby increasing the risk of vascular throm bosis, include hypoxia, dehydration, acidosis, hyper viscosity and the percentage of abnormal haemoglobin.6 The combination of sickle trait and a significant degree of one or more of these factors may provoke sickle retinopathy. Three cases are reported to emphasise the importance of considering sickle trait as relevant to the management of eye disease in at-risk patients. presented to the eye casualty having been hit in the left eye by a paper pellet. On examination the vision was right 6/5 and left 6/18. On the left side a 5 mm hyphaema was present, the pupil was round and reactive and the intraocular pressure (lOP) was 18 mmHg. Dilated funduscopy was normal. The follow ing day the hyphaema had reduced in size but the lOP had risen to 38 mmHg, hence topical and oral ocular antihypertensive agents were introduced. Haemoglobin (Hb) electrophoresis revealed AS sickle trait with an HbS concentration of 38.3%. The next day the lOP had risen to 53 mmHg and oral glycerol was added to the regime. There was good response to this treatment, with the lOP returning to normal and gradual resolution of the hyphaema. Gonioscopy confirmed angle recession nasally.Six days after admission the patient was noted to have scattered preretinal and sub hyaloid haemor rhages in the temporal mid-periphery, but no retinal tears were identified. After 14 days the visual acuity was 6/6-3, the eye was quiet with no hyphaema and the rop was 13 mmHg. The haemorrhages in the mid-periphery remained and occluded vessels invol ving almost all of the peripheral retina were seen (Fig. 1). Six weeks after the incident the haemor rhages had resolved but there was no change in the appearance of the peripheral vasculature. A fluor escein angiogram (Fig. 2) showed extensive periph eral occlusion but no neovascularisation.The other fundus is normal and the lOP has remained at 12-15 mmHg on no treatment. Case 2A 59-year-old Jamaican woman was referred from the diabetic clinic because of reduced visual acuity and the finding of background diabetic retinopathy. She had been an insulin-dependent diabetic for 30 years, hypertension had been diagnosed 4 years previously and this was well controlled on nifedipine and a diuretic. She did not smoke. Visual acuity was Eye (1995) 9,589-593

Evidence for bilineal inheritance of physiological indicators of risk in childhood-onset schizophrenia

“…The heterozygotic form of the illness, in which the gene from one parent produces hemoglobin S while the gene from the other parent produces hemoglobin A (Hb AS), results in 35-45% sickling cells, a condition known as sickle cell trait [Forget, 1985]. Although the majority of heterozygotes are clinically asymptomatic, Hb AS, in combination with environmentally induced hypoxia-such as high altitude airplane flights, a move to a higher altitude, or extreme exercise-can lead to a sudden onset of symptoms in adulthood [Davis et al, 1995;Diggs, 1984aDiggs, , 1984bHumphries and Wheby, 1992;Jackson et al., 1995; Kerle and Nishimura, 1996;Lane and Githens, 1985;Tollin and Seely, 1994]. For example, new armed services recruits with Hb AS are 30-40 times more likely to suffer sudden death under the stress of basic training than are their normal hemoglobin Hb AA counterparts [Kark et al, 1987].…”

Simple visual reaction time in sickle cell disease patients of pediatric age group

“…Sickling of erythrocytes within small vessels leading to occlusion of vessels, leading to ischemia furthering neovascular proliferation may be the reason for the ophthalmic manifestations of sickle cell disease. [23] Optic nerve involvement may also occur as a sequelae to ischemia in sickle cell patients. [24] Significantly increased VRT in pediatric sickle cell patients in the absence of any ocular symptoms or ocular findings may point toward the subclinical involvement of the visual transmission pathway which should be explored further.…”

Sickle Cell Trait: A Benign State?

“…A significant positive correlation was found between the severity of conjunctival vasculopathy and the percentage of sickle hemoglobin in 65 subjects with various sickle cell hemoglobinopathies, which included SCT [38] . In a report of 3 cases with sickle cell retinopathy, 1 was associated with traumatic hyphema and raised intraocular pressure, while the other 2 were associated with diabetes [39] , leading to the conclusion that the sickle cell retinopathy is related more to the associated systemic pathologies. To assess if sickle cell retinopathy was as a result of accompanying systemic pathologies or not ophthalmic examination was performed on parents of children with sickle cell anemia.…”