FEATURE

Sickle cell : an overview of vitreoretinal complications and their surgical management

BY ANTONIO BERARDUCCI, TOM WILLIAMSON

ickle cell disease is the most blood vessels, causing vascular occlusion common genetic disorder in multiple organs including the worldwide and is associated with with a number of clinical features in the Slifelong anaemia, intermittent eye [1,2]. The conjunctival and pain and multi-organ morbidity. Ocular head blood vessels show characteristic involvement can be associated with segmentation of blood columns in the significant due to homozygous sickle cell disease (SS) [3]. the complications of proliferative sickle The blood cells occlude the retinal blood (PSR). Occasionally it presents vessel causing hypoxia that stimulates with vitreoretinal complications and if neovascularisation. In the retina black surgery is required these eyes respond sunburst spots, iridescent spots, retinal well to procedures with haemorrhages (salmon patches) and sea segmentation of sea fan proliferation. fan neovascular proliferation occur. There may be comma shaped vessels on the Background bulbar and atrophy and The sickle cell haemoglobinopathies spontaneous hyphaema can occur and result from an abnormality in the beta cause raised intraocular pressure with risk chain of the haemoglobin molecule and of rebleeding. the disease can be distinguished in sickle Retinal complications are seen in 43% cell trait (Hb AS), sickle cell anaemia- of patients aged between 20 and 30 years homozygous sickle cell disease (SS with doubly heterozygous sickle cell [4]. disease), sickle cell disease-heterozygous The process also causes secondary changes sickle cell C disease (SC disease) and in the vitreous which stimulate epiretinal sickle cell thalasaemia disease (S-thal membrane (ERM) formation and macular disease). It is an autosomal incomplete holes as well as dominant condition (inheritance is similar (5.3%) and tractional to recessive inheritance with one in four (TRD), along with retinal break formation chance of SS if both parents AS) but the and rhegmatogenous retinal detachment S gene can have effects if combined with (RRD, 2%) [1,5]. Reports of vitreoretinal the C gene or thalasaemia gene. The sickle surgery for these complications are few “This hereditary gene is present in approximately 8% of and are often from when scleral buckling the Afro-American population in the USA and panretinal photocoagulation were disorder causes the but can be higher or lower depending used [6,7,8]. The use of scatter laser as a red blood cells to take on geographical location. The gene is means of regressing neovascularisation is thought to have originated in West Africa controversial because of the high incidence on a sickle shape with where it is present in 10 to 14% of the of autoinfarction of the retinal proliferation population because of its protective effect in 30% [9]. Occlusion of the feeder vessels the result of being in falciparum malaria (shorter living red supplying sea fans has been employed, rigid and passing blood cells and relative hypoxia may be feeder vessel laser has been associated detrimental to the infection). The gene with retinal break formation and choroidal with more difficulty is also seen in eastern Mediterranean neovascularisation but has been shown in a through blood vessels, and Middle Eastern patients. SC disease small randomised study to reduce the risk is traditionally thought to develop more of vitreous haemorrhage [10]. More recent causing vascular retinal complications, however, the reports on modern vitreoretinal techniques complications are also seen in SS disease. in are rare despite occlusion in multiple Most cases of retinopathy seem to appear considerable development of surgical organs including the between 20 and 40 years and stabilise or technique. regress thereafter. This hereditary disorder Visual loss in HbSC patients is almost retina.” causes the red blood cells to take on a entirely due to (PSR), whereas in patients sickle shape with the result of being rigid with HbSS cerebral or retinal vaso- and passing with more difficulty through occlusive events are more likely to cause

eye news | DECEMBER/JANUARY 2017 | VOL 23 NO 4 | www.eyenews.uk.com FEATURE

blindness [11]. However, the most showing spontaneous improvement. eight patients with RRD (24.2%), six common cause of visual loss is still Intravitreal bevacizumab (Avastin) has patients with TRD (18.1%), two patients retinal detachment (RD), the prevalence been used off label in and a more rapid with ERM (6%) and one patient with of which is almost twice as high in the resolution of the vitreous haemorrhage macular hole (3%). The visual acuity HbSC disease compared to HbSS. An in Goldberg stage 4 PSR has been measured preoperatively was between incidence of visual loss has previously reported [18]. -0.07 and 2.29 logMar (mean 1.23; SD been estimated at 1.5% per person-years Patients with vitreous haemorrhage, 0.94); none of the patients had previous [12]. TRD, RRD and macular disorders such laser treatment or retinal surgery. as ERM and macular holes can be was present preoperatively in Expert commentary successfully treated with pars plana seven patients (21.2%) and all patients Ocular involvement in patients vitrectomy (PPV) [19]. The most recent underwent 20, 23 or 25G, three ports with sickle cell disease (SCD) can description of surgery is from 2005 PPV. Iatrogenic retinal tears occurred be associated with significant visual [19,20]. Scleral buckling was used in in 22 patients (33.3%), cryotherapy impairment predominantly due to the the past with scatter photocoagulation retinopexy was performed in 10 patients complications of (PSR) consisting of [21], both preoperatively [22] and (30.3%), endolaser PRP in four patients vitreous haemorrhage (VH) and (RD) peroperatively [23] in many centres who had in addition [11]. Rarer causes of visual loss in this [24,25] but anterior segment necrosis (12.1%), laser retinopexy in three (9%) population include retinal artery and has been reported following scleral and cryotherapy plus laser retinopexy retinal vein occlusions, anterior segment buckle [26,27]. More commonly pars in three cases (9%). Delamination was ischaemia, and secondary plana vitrectomy is now used, without performed in 10 cases (30.3%) and [12-14]. Development and progression of external plombage or scatter laser [19]. internal tamponade was necessary in 22 PSR is most common in patients aged Peroperative PPV complications are very cases. The postoperative visual acuity 20-39 years [15]. Natural course of the frequent, in particular there is a high at discharge was between -0.7 and disease indicates possible spontaneous incidence of iatrogenic tears formation 2.29 logMar (mean 0.3 logMar; SD 0.8). autoinfarctions in adults over age 40 during PPV especially, around sea fan In conclusion, sickle cell retinopathy particularly in patients with HbSS complexes [19,21]. For this reason, during occasionally presents with vitreoretinal disease [15,16]. Some current guidelines vitrectomy, the sea fans should be safely complications. Surgically these patients propose annual review of patients and left in situ and a segmentation technique appear challenging preoperatively screening for sickle retinopathy. It used to remove vitreal attachments. In but are relatively forgiving if minimal has been suggested by some authors addition there is no need to try to induce surgery by PPV, macular membrane that patients with sickle cell disease regression of the sea fans with scatter peel, posterior hyaloid separation, must undergo regular ophthalmologic laser or feeder vessel laser [19]. Cataract segmentation of sea fans and no evaluations starting as early as age 10 formation after surgery is uncommon panretinal photocoagulation are used years to detect ocular abnormalities [15]. possibly because of the young age [29]. Some patients can be observed and Despite this, a large retrospective cohort of the patients but also because the may spontaneously regress. If surgery study of patients with sickle cell disease relative ischaemia of these eyes may is required, these eyes respond very in the UK has suggested that patients have protective effects [28]. Exchange well to vitrectomy procedures with with SCD and no visual symptoms are transfusion once used before surgery is segmentation of sea fan proliferation. unlikely to have retinal disease, which no longer considered necessary. Neither scleral buckling, panretinal requires intervention [17]. In fact, many Reviewing 33 patients receiving PPV photocoagulation nor delamination are patients with vitreoretinal complications for complications related to sickle necessary for good outcomes. from sickle cell retinopathy such as cell eye disease between 2001 and vitreous haemorrhage can be allowed 2015 shows 14 males and 19 females References to clear without detriment. TRD can be of age between 20 and 72 years, mean 1. Clarkson JG. The ocular manifestations of sickle- observed without apparent progression 41.7 years. Sixteen patients presented cell disease: a prevalence and natural history study. 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III Neovascular proliferation in the far periphery giving a ‘sea fan’ 6. Treister G, Machemer R. Results of vitrectomy appearance. These often auto infarct and are commonest in SC disease. for rare proliferative and hemorrhagic diseases. Am J Ophthalmol 1977;84:394-412. 7. Ryan SJ. Role of the vitreous in the IV Vitreous haemorrhage. haemoglobinopathies. Trans Ophthalmol Soc UK 1975;95:403-6. V Retinal detachment either tractional or rhegmatogenous. 8. Morgan CM, D’Amico DJ. Vitrectomy surgery in proliferative sickle retinopathy. Am J Ophthalmol 1987;104:133-8.

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eye news | DECEMBER/JANUARY 2017 | VOL 23 NO 4 | www.eyenews.uk.com