Treatment-related non-fibrotic scars do not negatively affect vision
medwireNews: Developing non-fibrotic scars (NFS) during the first year of anti-vascular endothelial growth factor treatment does not have a detrimental effect on visual acuity (VA) during the following 4 years, US researchers report.
Furthermore, the sustained level of good vision occurred “[d]espite the continued evolution of NFS over 5 years”, Ebenezer Daniel (University of Pennsylvania, Philadelphia) and co-authors write in Ophthalmology.
The 5-year follow-up of participants in the Comparison of Age-related Macular Degeneration Treatments Trials (CATT) included 474 eyes with colour fundus photographs and fluorescein angiograms available from years 1, 2 and 5 of the study. All participants had received ranibizumab or bevacizumab according to one of three dosing regimens.
At 1 year, 39 (8.2%) eyes had NFS, defined as flat, small, well-circumscribed areas of pigmentation with varying degrees of central hypopigmentation without exposure of underlying choroidal vessels, at the site of baseline choroidal neovascularization.
A further 68 (14.3%) eyes had fibrotic scar (FS) and the remaining 367 (77.4%) had no scar.
At baseline, the mean total choroidal neovascularization (CNV) lesion area was 2.3, 8.2 and 6.3 mm2 for the NFS, FS and no scar groups, respectively. This increased significantly over time in all groups but remained smallest in the NFS eyes, with average 5-year values of 5.8, 17.1 and 12.5 mm2, respectively.
Among the eyes with NFS at year 1, FS developed in 5% and 28% at 2 and 5 years, respectively, geographic atrophy developed in 5% and 21%, respectively, while non-geographic atrophy was present in 34%, 47% and 65% of these eyes at 1, 2 and 5 years, respectively.
The researchers note that NFS eyes at year 1 had significantly less geographic atrophy, intraretinal fluid and subretinal pigment epithelium fluid at year 5 than eyes with FS or no scar at year 1.
The team also reports that mean thickness of the retina, subretinal fluid, subretinal tissue complex and total retina did not change significantly with time in the NFS eyes. By contrast, all but subretinal fluid thickness grew significantly thinner with time among the eyes with no scar at year 1.
The proportion of NFS eyes with subretinal hyperreflective material almost halved from baseline to 5 years (90 vs 49%), whereas it fell by approximately 10% in the eyes with no scar (71 vs 63%) and increased in the eyes with FS (88 vs 93%).
At 5 years, mean VA was 73 letters (approximately 20/32) in the NFS group, which was significantly higher than the baseline value of 66 letters (approximately 20/50), and also significantly higher than the 5-year values for both the FS (48 letters, approximately 20/100) and no scar groups (62 letters, approximately 20/63).
Daniel et al say their findings indicate that “the development of a nonfibrotic scar is far more preferable than the development of a fibrotic scar.”
They continue: “Non-fibrotic scars tend to maintain better VA over time and develop far fewer destructive pathological changes than a fibrotic scar.
“Better understanding of nonfibrotic scars and how and why they differ from fibrotic scars may lead to the identification of future therapeutic targets that reduce fibrosis and scar formation.”
By Laura Cowen
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