Hemoglobinopathies

Laser therapy for retinopathy in sickle cell disease

BACKGROUND

Sickle cell disease (SCD) includes a group of inherited haemoglobinopathies affecting multiple organs including the eyes. Some people with SCD develop ocular manifestations. Vision-threatening complications are mainly due to proliferative sickle retinopathy, which is characterised by proliferation of new blood vessels. Laser photocoagulation is widely applicable in proliferative retinopathies. It is important to evaluate the efficacy and safety of laser photocoagulation in the treatment of proliferative sickle retinopathy (PSR) to prevent sight-threatening complications.

OBJECTIVES

To evaluate the effectiveness of various techniques of laser photocoagulation therapy in SCD-related proliferative retinopathy.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. Date of last search: 4 July 2022. We also searched the following resources (26 June 2022): Latin American and Caribbean Health Science Literature Database (LILACS); WHO International Clinical Trials Registry Platforms (ICTRP); and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials comparing laser photocoagulation to no treatment in children and adults with SCD.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility and risk of bias of the included trials; we extracted and analysed data, contacting trial authors for additional information. We assessed the certainty of the evidence using the GRADE criteria.

MAIN RESULTS

We included three trials (414 eyes of 339 children and adults) comparing the efficacy and safety of laser photocoagulation to no therapy in people with PSR. There were 160 males and 179 females ranging in age from 13 to 67 years. The trials used different laser photocoagulation techniques; one single-centre trial employed sectoral scatter laser photocoagulation using an argon laser; a two-centre trial employed feeder vessel coagulation using argon laser in one centre and xenon arc in the second centre; while a third trial employed focal scatter laser photocoagulation using argon laser. The mean follow-up periods were 21 to 32 months in one trial, 42 to 47 months in a second, and 48 months in the third. Two trials had a high risk of allocation bias due to the randomisation method for participants with bilateral disease; the third trial had an unclear risk of selection bias. One trial was at risk of reporting bias. Given the unit of analysis is the eye rather than the individual, we chose to report the data narratively. Using sectoral scatter laser photocoagulation, one trial (174 eyes) reported no difference between groups for complete regression of PSR: 30.2% in the laser group and 22.4% in the control group. The same trial also reported no difference between groups in the development of new PSR: 34.3% of lasered eyes and 41.3% of control eyes (very low-certainty evidence). The two-centre trial using feeder vessel coagulation, only presented data at follow-up for one centre (mean period of nine years) and reported the development of new sea fan in 48.0% in the treated and 45.0% in the control group; no statistical significance (P = 0.64). A third trial reported regression in 55% of the laser group versus 28.6% of controls and progression of PSR in 10.5% of treated versus 25.7% of control eyes. We graded the evidence for these two primary outcomes as very low-certainty evidence. The sectoral scatter laser photocoagulation trial reported visual loss in 3.0% of treated eyes (mean follow-up 47 months) versus 12.0% of controlled eyes (mean follow-up 42 months) (P = 0.019). The feeder vessel coagulation trial reported visual loss in 1.14% of the laser group and 7.5% of the control group (mean follow-up 26 months at one site and 32 months in another) (P = 0.07). The focal scatter laser photocoagulation trial (mean follow-up of four years) reported that 72/73 eyes had the same visual acuity, while visual loss was seen in only one eye from the control group. We graded the certainty of the evidence as very low. The sectoral scatter laser trial detected vitreous haemorrhage in 12.0% of the laser group and 25.3% of control with a mean follow-up of 42 (control) to 47 months (treated) (P ≤ 0.5). The two-centre feeder vessel coagulation trial observed vitreous haemorrhage in 3.4% treated eyes (mean follow-up 26 months) versus 27.5% control eyes (mean follow-up 32 months); one centre (mean follow-up nine years) reported vitreous haemorrhage in 1/25 eyes (4.0%) in the treatment group and 9/20 eyes (45.0%) in the control group (P = 0.002). The scatter laser photocoagulation trial reported that vitreous haemorrhage was not seen in the treated group compared to 6/35 (17.1%) eyes in the control group and appeared only in the grades B and (PSR) stage III) (P < 0.05). We graded evidence for this outcome as low-certainty. Regarding adverse effects, only one occurrence of retinal tear was reported. All three trials reported on retinal detachment, with no significance across the treatment and control groups (low-certainty evidence). One trial reported on choroidal neovascularization, with treatment with xenon arc found to be associated with a significantly higher risk, but visual loss related to this complication is uncommon with long-term follow-up of three years or more. The included trials did not report on other adverse effects or quality of life.

AUTHORS' CONCLUSIONS

Our conclusions are based on the data from three trials (two of which were conducted over 30 years ago). Given the limited evidence available, which we assessed to be of low- or very low-certainty, we are uncertain whether laser therapy for sickle cell retinopathy improves the outcomes measured in this review. This treatment does not appear to have an effect on clinical outcomes such as regression of PSR and development of new incidences. No evidence is available assessing efficacy in relation to patient-important outcomes (such as quality of life or the loss of a driving licence).  Further research is needed to examine the safety of laser treatment compared to other interventions such as intravitreal injection of anti-vascular endothelial growth factors (VEGFs) . Patient-important outcomes as well as cost-effectiveness should be addressed.

Analysis of the foveal microvasculature in sickle cell disease using swept-source optical coherence tomography angiography

Ischemic microangiopathy was clearly identified in sickle cell disease (SCD) using fluorescein angiography. A prospective observational clinical study was conducted to assess the foveal avascular zone (FAZ) area and explore perifoveal microvasculature changes in the superficial (SCP) and deep (DCP) capillary plexus using optical coherence tomography angiography (OCTA) and compare two genotypes—HbS/HbS (HbSS) and HbS/HbC (HbSC)-to control. All consecutive patients with electrophoretic confirmation of SCD were included. Swept-source OCTA scans (Triton Plus, Topcon, Tokyo, Japan) with a 3 × 3-mm scanning area and ultra-wide field (UWF) retinography (California, Optos, Fife, Scotland) were recorded for all patients. For OCTA analysis, preset parameters were used to segment the SCP and DCP. The FAZ area was manually assessed. The number of vascular branching points was automatically assessed based on the vascular skeletonization using ImageJ software. Eyes were staged based on Goldberg’s classification of SCD retinopathy (SCDR) using UWF imaging. Forty-six eyes of 24 patients were included in the HbSS (n = 27) and HbSC (n = 19) groups and 16 eyes of 8 unaffected patients in a control group. In the DCP, the FAZ was significantly larger in the HbSC (p = 0.0001) and HbSS (p = 0.0004) groups compared to controls. The FAZ area in the SCP, CRT and number of superficial vascular branching points did not significantly differ between both genotypes. There were less branching points in the HbSC (p = 0.034) and HbSS (p = 0.0014) groups than in controls. The Goldberg stage was significantly higher in the HbSC group than in the HbSS group (2.21 vs. 1.22, p = 0.0062). OCTA provides useful information on macular microvasculature and structural alterations associated with SCDR. Ischemic abnormalities are more predominant in the DCP in case of SCDR and no difference was found between genotypes of patients visually asymptomatic.

The past, present and future management of sickle cell retinopathy within an African context

Sickle cell retinopathy is a potentially blinding condition that affects young people in the working age group. This review looks at the past, present and future management of sickle cell retinopathy within an African context. After Sickle cell disease was first reported in 1910, some reports from Africa were pivotal in describing the retinal changes associated with the disease. It soon became obvious that there was a varied clinical picture and clinical course. Several landmark studies were carried out in Jamaica to help elucidate the complexities of the disease and outline appropriate clinical management. In most of the developed world, the clinical management of sickle cell disease has improved with concurrent improvement in outcomes. Currently resource constraints in most Sub-Saharan African countries where there is a high burden of disease means that the management of sickle cell retinopathy is fraught with numerous challenges. Future large scale trials in Africa shall hopefully help to better elucidate the mechanisms behind proliferative sickle retinopathy and help in the development of new and improved therapeutic pathways. The use of technology can help immensely in the screening of patients with sickle cell to detect early proliferative changes and if necessary treat accordingly.

Laser therapy for retinopathy in sickle cell disease

BACKGROUND

Sickle cell disease includes a group of inherited haemoglobinopathies affecting multiple organs including the eyes. Some people with the disease develop ocular manifestations due to vaso-occlusion. Vision-threatening complications of sickle cell disease are mainly due to proliferative sickle retinopathy which is characterized by proliferation of new blood vessels. Laser photocoagulation is widely applicable in proliferative retinopathies such as proliferative sickle retinopathy and proliferative diabetic retinopathy. It is important to evaluate the efficacy and safety of laser photocoagulation in the treatment of proliferative sickle retinopathy to prevent sight-threatening complications.

OBJECTIVES

To evaluate the effectiveness of various techniques of laser photocoagulation therapy in sickle cell disease-related retinopathy.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. Date of last search: 21 September 2015.We also searched the following resources (24 March 2015): Latin American and Carribean Health Science Literature Database (LILACS); WHO International Clinical Trials Registry Platforms (ICTRP); and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials comparing laser photocoagulation to no treatment in children and adults.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial eligibility, the risk of bias of the included trials and extracted and analysed data. We contacted the trial authors for additional information.

MAIN RESULTS

Two trials (341 eyes of 238 children and adults) were included comparing efficacy and safety of laser photocoagulation to no therapy in people with proliferative sickle retinopathy. There were 121 males and 117 females with an age range from 13 to 67 years. The laser photocoagulation technique used was different in the two trials; one single-centre trial employed sectoral scatter laser photocoagulation using an argon laser; and the second, two-centre trial, employed feeder vessel coagulation using argon laser in one centre and xenon arc in the second centre. The follow-up period ranged from a mean of 21 to 32 months in one trial and 42 to 47 months in the second. Both trials were at risk of selection bias (random sequence generation) because of the randomisation method employed for participants with bilateral disease. One study was considered to be at risk of reporting bias.Using sectoral scatter laser photocoagulation, one trial (174 eyes) reported that complete regression of proliferative sickle retinopathy was seen in 30.2% in the laser group and 22.4% in the control group (no difference between groups). The same trial reported the development of new proliferative sickle retinopathy in 34.3% of laser-treated eyes and in 41.3% of eyes given no treatment; again, there was no difference between treatment groups. The second trial, using feeder vessel coagulation, did not present full data for either treatment group for these outcomes.There was evidence from both trials (341 eyes) that laser photocoagulation using scatter laser or feeder vessel coagulation may prevent the loss of vision in eyes with proliferative sickle retinopathy (at median follow up of 21 to 47 months). Data from both trials indicated that laser treatment prevented the occurrence of vitreous haemorrhage with both argon and xenon laser; with the protective effect being greater with feeder vessel laser treatment compared to scatter photocoagulation.Regarding adverse effects, the incidence of retinal tear was minimal, with only one event reported. Combined data from both trials were available for 341 eyes; there was no difference between the laser and control arms for retinal detachment. In relation to choroidal neovascularization, treatment with xenon arc was found to be associated with a significantly higher risk, but visual loss related to this complication is uncommon with long-term follow up of three years or more.Data regarding quality of life and other adverse effects were not reported in the included trials.

AUTHORS' CONCLUSIONS

Our conclusions are based on the data from two trials conducted over 20 years ago. In the absence of further evidence, laser treatment for sickle cell disease-related retinopathy should be considered as a one of therapeutic options for preventing visual loss and vitreous haemorrhage. However, it does not appear to have a significant different effect on other clinical outcomes such as regression of proliferative sickle retinopathy and development of new ones. No evidence is available assessing efficacy in relation to patient-important outcomes (such as quality of life or the loss of a driving licence). There is limited evidence on safety, overall, scatter argon laser photocoagulation is superior in terms of adverse effects, although feeder vessel coagulation has a better effect in preventing vitreous haemorrhage. Further research is needed to examine the safety of laser treatment compared to other interventions such as intravitreal injection of anti-vascular endothelial growth factors. In addition, patient-important outcomes as well as cost-effectiveness should be addressed.

Conjunctival microvascular haemodynamics in sickle cell retinopathy

PURPOSE

To determine alterations in bulbar conjunctival microvascular haemodynamics in sickle cell retinopathy (SCR) subjects with focal macular thinning (FMT).

METHODS

Conjunctival microcirculation imaging and spectral domain optical coherence tomography (SD-OCT) were performed in 22 subjects (eyes) diagnosed with SCR. Based on evaluation of SD-OCT retinal thickness maps, eyes were assigned to one of the two groups: with or without FMT. Conjunctival venular diameter and axial blood velocity were measured in multiple venules in each eye by customized image analysis algorithms. Measurements were then categorized into two vessel size groups (vessel size 1 and 2) and compared between FMT groups. A Pearson correlation coefficient was computed to assess the relationship between retinal thickness and axial blood velocity.

RESULTS

Mean age, haematocrit, sickle cell haemoglobin type and median retinopathy score were not significantly different between the two groups (p ≥ 0.1). Retinal thickness in parafoveal and perifoveal temporal subfields was significantly lower in eyes with FMT as compared to eyes without FMT (p ≤ 0.04). There was a significant effect of FMT on axial blood velocity (p = 0.04), while the effect of vessel size was not significant (p = 0.4). In vessel size 1, axial blood velocity was lower in eyes with FMT than in eyes without FMT (p = 0.03), while in vessel size 2, there was no statistically significant difference between FMT groups (p = 0.1). In vessel size 1, there was a significant positive correlation between axial blood velocity and retinal thickness in the perifoveal (r = 0.48, p = 0.02) and parafoveal (r = 0.43, p = 0.04) temporal subfields.

CONCLUSION

Conjunctival axial blood velocity in small venules is reduced in SCR subjects with focal macular thinning.

An evidence-based review of vascular endothelial growth factor inhibition in pediatric retinal diseases: part 2. Coats' disease, best disease, and uveitis with childhood neovascularization

Vascular endothelial growth factor (VEGF) is an important factor in the pathogenesis of multiple retinal neovascular disorders. This report focuses on the quality and depth of new evidence for the use of VEGF inhibitors in selected pediatric ocular diseases, including Coats' disease, Best disease, and childhood uveitis. Because much of the literature comprises case reports and retrospective case series, the level of evidence supporting its use as a primary treatment option, or even as adjuvant therapy, is low. The standard of care is treatment of the underlying disorder to prevent neovascularization (retinal or subretinal), vitreous hemorrhage, or subsequent retinal detachment. However, these complications may not present until late in the disease course. It may then be useful to treat with these agents. Prospective studies are warranted to further elucidate the role of anti-VEGF therapy in these diseases.

[Screening for sickle cell disease retinopathy in the north of France]

OBJECTIVE

To study the frequency and the severity of retinopathy in adult patients with sickle cell disease in the north of France.

PATIENTS AND METHODS

Patients with sickle cell disease aged more than 18 years old were consecutively referred for screening of sickle cell retinopathy in the ophthalmology department from December 2005 to March 2008. Complete ophthalmologic examination with dilated funduscopy was performed in each patient. Fluorescein angiography was performed in cases with ischemic retinopathy. Goldberg and Penman classifications were used to grade retinopathy severity.

RESULTS

Fifty-five patients (100 eyes) were included (26 S/S, 9 S/C, 12 S/B, 3 S/S with hereditary persistence of fetal hemoglobin). Sickle cell retinopathy is more severe in patients with the S/C genotype than the S/S and S/B genotypes. Proliferative retinopathy is more common in S/C patients than S/S and S/B patients (S/C vs S/S, p=0.001; S/C vs SB, p=0.01). A qualitatively abnormal vascular border (type II) is also more frequent in S/C patients than S/S and S/B patients (S/C vs S/S, p=0.001; S/C vs SB, p=0.01). No proliferative retinopathy was found in patients with S/S and hereditary persistence of fetal hemoglobin syndrome.

CONCLUSIONS

Screening is useful to detect sickle cell retinopathy, particularly in the adult population, to prevent complications from proliferative retinopathy.