Susan Downes

Prof. Dr. Susan Downes

Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, UK
+2
orcid

Research Focus & Metrics

Academic Career Length

22Years (2005-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
1 October 2018 in Ophthalmology
Verified
Journal Article
Open access
EDElon H.C. van Dijk
Elon H.C. van Dijk
SFSascha Fauser
Sascha Fauser
MBMyrte B. Breukink
Myrte B. Breukink
RBRocio Blanco-Garavito
Rocio Blanco-Garavito
HGHans Groenewoud
Hans Groenewoud
CBCamiel Boon
Camiel Boon
To compare the anatomic and functional efficacy and safety of half-dose photodynamic therapy (PDT) versus high-density subthreshold micropulse laser (HSML) treatment in patients with chronic central serous chorioretinopathy (cCSC). Open-label, multicenter, randomized controlled clinical trial. Patients with cCSC whose disease had to be confirmed by both clinical characteristics and findings on multimodal imaging. Eligible patients were randomized in a 1:1 allocation ratio. Treatment was evaluated during a follow-up visit, and the same treatment was repeated in patients who still demonstrated subretinal fluid (SRF). The primary end point was the complete disappearance of SRF at the first evaluation visit at 6 to 8 weeks after treatment. As a secondary outcome measure, we assessed this anatomic result at the final evaluation visit at 7 to 8 months after treatment. Other secondary outcomes covered functional improvement and included change in best-corrected visual acuity (BCVA; measured in Early Treatment Diabetic Retinopathy Study [ETDRS] letters), retinal sensitivity (measured using microperimetry), and vision-related quality of life using a validated questionnaire. Between November 2013 and September 2016, 179 patients were included: 89 patients were assigned randomly to half-dose PDT, and 90 were assigned randomly to HSML treatment. At their first evaluation visit, SRF had resolved in 51.2% and 13.8% of patients, respectively (P < 0.001). At their final evaluation visit, a significantly higher percentage of PDT-treated patients demonstrated no SRF (67.2% vs. 28.8%; P < 0.001). Moreover, at the first evaluation visit, the PDT-treated patients showed a significantly higher increase in BCVA (+4.60±6.62 ETDRS letters vs. +1.39±8.99 ETDRS letters; P = 0.011), and a significantly higher increase in retinal sensitivity on microperimetry (+2.01±3.04 dB vs. +0.92±3.65 dB; P = 0.046); however, the improvement in vision-related quality of life was similar (score of +2.87±8.35 vs. +2.56±7.36, respectively; P = 0.800). Half-dose PDT is superior to HSML for treating cCSC, leading to a significantly higher proportion of patients with complete resolution of SRF and functional improvement.

10 March 2017 in Eye
Verified
Journal Article
Closed access
IYImran Yusuf
Imran Yusuf
SSS Sharma
S Sharma
RLR Luqmani
R Luqmani
SDSusan Downes
Susan Downes

13 August 2021 in Genes
Verified
Journal Article
Open access
PDF file
SASaoud Al-khuzaei
Saoud Al-khuzaei
SBSuzanne Broadgate
Suzanne Broadgate
CFCharlotte R. Foster
Charlotte R. Foster
MSMital Shah
Mital Shah
JYJing Yu
Jing Yu
SHStephanie Halford
Stephanie Halford
Stargardt disease (STGD1) and ABCA4 retinopathies (ABCA4R) are caused by pathogenic variants in the ABCA4 gene inherited in an autosomal recessive manner. The gene encodes an importer flippase protein that prevents the build-up of vitamin A derivatives that are toxic to the RPE. Diagnosing ABCA4R is complex due to its phenotypic variability and the presence of other inherited retinal dystrophy phenocopies. ABCA4 is a large gene, comprising 50 exons; to date > 2000 variants have been described. These include missense, nonsense, splicing, structural, and deep intronic variants. Missense variants account for the majority of variants in ABCA4. However, in a significant proportion of patients with an ABCA4R phenotype, a second variant in ABCA4 is not identified. This could be due to the presence of yet unknown variants, or hypomorphic alleles being incorrectly classified as benign, or the possibility that the disease is caused by a variant in another gene. This underlines the importance of accurate genetic testing. The pathogenicity of novel variants can be predicted using in silico programs, but these rely on databases that are not ethnically diverse, thus highlighting the need for studies in differing populations. Functional studies in vitro are useful towards assessing protein function but do not directly measure the flippase activity. Obtaining an accurate molecular diagnosis is becoming increasingly more important as targeted therapeutic options become available; these include pharmacological, gene-based, and cell replacement-based therapies. The aim of this review is to provide an update on the current status of genotyping in ABCA4 and the status of the therapeutic approaches being investigated.

18 December 2018 in Genes
Verified
Journal Article
Open access
PDF file
ANAnika Nanda
Anika Nanda
ASAnna Paola Salvetti
Anna Paola Salvetti
PCPenny Clouston
Penny Clouston
SDSusan Downes
Susan Downes
RMRobert E MacLaren
Robert E MacLaren
Inherited retinal degenerations are the leading cause of blindness in the working population. X-linked retinitis pigmentosa (XLRP), caused by mutations in the Retinitis pigmentosa GTPase regulator (RPGR) gene is one of the more severe forms, and female carriers of RPGR mutations have a variable presentation. A retrospective review of twenty-three female RPGR carriers aged between 8 and 76 years old was carried out using fundoscopy, autofluorescence imaging (AF), blue reflectance (BR) imaging and optical coherence tomography (OCT). Confirmation of the genetic mutation was obtained from male relatives or Sanger genetic sequencing. Fundus examination and AF demonstrate phenotypic variability in RPGR carriers. The genetic mutation appears indeterminate of the degree of change. We found four distinct classifications based on AF images to describe RPGR carriers; normal (N) representing normal or near-normal AF appearance (n = 1, 4%); radial (R) pattern reflex without pigmentary retinopathy (n = 14, 61%); focal (F) pigmentary retinopathy (n = 5, 22%) and; male (M) phenotype (n = 3, 13%). The phenotypes were precisely correlated in both eyes (rs = 1.0, p < 0.0001). Skewed X-inactivation can result in severely affected carrier females—in some cases indistinguishable from the male pattern and these patients should be considered for RPGR gene therapy. In the cases of the male (M) phenotype where the X-inactivation was skewed, the pattern was similar in both eyes, suggesting that the mechanism is not truly random but may have an underlying genetic basis.

1 August 2014 in Investigative Ophthalmology & Visual Science
Verified
Journal Article
Open access
PDF file
IAIona Alexander
Iona Alexander
FCFiona M. Cuthbertson
Fiona M. Cuthbertson
GRGokulan Ratnarajan
Gokulan Ratnarajan
RSRukhsana Safa
Rukhsana Safa
FMFaye E. Mellington
Faye E. Mellington
KWKatharina Wulff
Katharina Wulff
Purpose. Although visual impairment is a well-recognized consequence of cataract development, little is known about the ability of the melanopsin-based photosensitive retinal ganglion cells (pRGCs) to regulate sleep–wake timing in the presence of cataract. In this study, we replaced a cataractous natural crystalline lens with two different types of artificial intraocular lenses, a UV-blocking lens or a blue-filtering lens. We investigated the level of sleep disturbance before cataract surgery and any change in sleep due to improved light transmission following surgery and compared this in both types of intraocular lens. Methods. Quality of sleep in 961 patients undergoing cataract surgery was assessed by administering the validated self-reported Pittsburgh Sleep Quality Index (PSQI) questionnaire. The PSQI distinguishes good sleepers from poor sleepers by scoring seven different sleep components over the last month, which are combined to produce an overall score for sleep quality. Patients received either an ultraviolet-blocking (UVB) clear intraocular lens (IOL) or a blue-filtering (BF) IOL. Questionnaires were completed four times: 1 month preoperatively and again 1, 6 (UVB-IOL only), and 12 months postoperatively. Results. Half of the patients reported poor sleep in the presence of cataract in both the UVB-IOL (mean PSQI = 6.35; SD = 3.82) and BF-IOL (mean PSQI = 6.39; SD = 4.04) groups. Cataract removal improved overall sleep quality significantly 1 month postoperatively in the UVB-IOL (mean PSQI = 5.89; SD = 3.71) and BF-IOL (mean PSQI = 6.08; SD = 3.88) groups. Sleep latency also improved for the UVB-IOL (preoperative mean = 1.16; SD = 1.003) and BF-IOL (preoperative mean = 1.17; SD = 1.03) groups at 1 month (UVB-IOL group mean = 1.01; SD = 0.923 and BF-IOL group mean = 1.00; SD = 0.95), which was sustained at 6 months for the UVB-IOL group (mean = 1.02; SD = 0.93) and 12 months for both the UVB-IOL and BF-IOL groups (6 months: UVB-IOL group mean = 0.96; SD = 0.92 and for the BF-IOL group mean = 0.99; SD = 0.96). Conclusions. Overall sleep quality and sleep latency improves after removal of cataract irrespective of the type of IOL implanted. These data show that implantation of BF-IOL does not have a negative impact on the sleep–wake cycle.

1 June 2015 in Ophthalmology
Verified
Journal Article
Closed access
TEThomas L. Edwards
Thomas L. Edwards
MGMarkus Groppe
Markus Groppe
JJJasleen K Jolly
Jasleen K Jolly
SDSusan Downes
Susan Downes
RMRobert E MacLaren
Robert E MacLaren