title: The influence of background diabetic retinopathy in the second eye on rates of progression of diabetic retinopathy between 2005 and 2010.
abstract: OBJECTIVE
  The Gloucestershire Diabetic Eye Screening Programme offers annual digital photographic screening for diabetic retinopathy to a countywide population of people with diabetes. This study was designed to investigate progression of diabetic retinopathy in this programme of the English NHS Diabetic Eye Screening Programme.
  
  
  METHODS
  Mydriatic digital retinal photographs of people with diabetes screened on at least 2 occasions between 2005 and 2010 were graded and included in this study if the classification at first screening was no DR (R0), background DR in one (R1a) or both eyes (R1b). Times to detection of referable diabetic retinopathy (RDR) comprising maculopathy (M1), preproliferative (R2) or proliferative retinopathy (R3) were analysed using survival models.
  
  
  RESULTS
  Data were available on 19 044 patients, 56% men, age at screening 66 (57-74) years (median, 25th, 75th centile). A total of 8.3% of those with R1a and 28.2% of those with R1b progressed to any RDR, hazard ratios 2.9 [2.5-3.3] and 11.3 [10.0-12.8]. Similarly 7.1% and 0.11% of those with R1a progressed to M1 and R3, hazard ratios 2.7 [2.3-3.2] and 1.6 [0.5-5.0], compared to 21.8% and 1.07% of those with R1b, hazard ratio 9.1 [7.8-10.4] and 15.0 [7.1-31.5].
  
  
  CONCLUSIONS
  The risk of progression is significantly higher for those with background DR in both eyes than those with background retinopathy in only one or in neither eye.
authors.affiliation: Gloucestershire Diabetic Retinopathy Research Group, Cheltenham General Hospital, Cheltenham, UK. peter.scanlon@glos.nhs.uk
authors.forename: Peter H
authors.initials: PH
authors.lastname: Scanlon
authors.forename: Irene M
authors.initials: IM
authors.lastname: Stratton
authors.forename: Mark
authors.initials: M
authors.lastname: Histed
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Chave
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Aldington
mesh_terms: D000368:Aged; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D010781:Photography; D012160:Retina / Q000473:pathology*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology
keywords: diabetic retinopathy; progression; risk factors; screening
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