title: Spatial changes of central field loss in diabetic retinopathy after laser.
abstract: OBJECTIVE
  To explore the spatial distribution of central visual field loss in untreated proliferative diabetic retinopathy (PDR) and to quantify the effect of medium-pulse Optos-guided 20-millisecond Pascal laser treatment on the central field.
  
  
  METHODS
  Visual field data (Swedish Interactive Threshold Algorithm 24-2) from 99 eyes (66 patients) with treatment-naive PDR were used to train a self-organizing map (SOM) that classified the defects into nine patterns. Twenty-eight eyes of 23 patients treated with 20-millisecond Pascal retinal laser photocoagulation underwent Optos widefield fundus fluorescein angiography (WF-FFA) at baseline and 3 months after treatment. Postlaser changes in SOM patterns and global indices were analyzed. Visual field defect changes (Total Deviation [TD]) with eccentricity and extent of initial loss were analyzed. Grading of WF-FFA after laser was undertaken by two masked retina specialists.
  
  
  RESULTS
  At baseline, 44.4% of PDR eyes showed early visual field loss patterns (1 to 3), with 23.2% classified into the advanced patterns (7 to 9). Mild SOM patterns had more superior hemifield field defects, whereas advanced patterns involved both superior and inferior hemifield field loss. After laser, a significant shift to early SOM patterns were observed (p = 0.02), as well as improvement of Mean Deviation and Pattern Standard Deviation (p = 0.003 and p = 0.06, respectively). Improvement of TD was commonly observed in test locations of 0 to 10, 10 to 20, and 20 to 30 degrees. Greater improvement was observed with deeper baseline TD (p < 0.001). Masked WF-FFA image grading showed 78.6% PDR regression.
  
  
  CONCLUSIONS
  The SOM method is a promising technique to classify and monitor over time PDR-associated visual field defects. Medium-pulse Optos-guided 20-millisecond Pascal laser treatment improved the spatial patterns and global parameters of central field defects.
authors.affiliation: *PhD †PhD, FRCOphth ‡MD §MBChB University of Manchester, Manchester, United Kingdom (YW, MMKM, PES, DBH); and Manchester Royal Eye Hospital, Manchester, United Kingdom (MMKM, PES, LBY, DBH).
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Wang
authors.forename: Mahiul M K
authors.initials: MM
authors.lastname: Muqit
authors.forename: Paulo E
authors.initials: PE
authors.lastname: Stanga
authors.forename: Lorna B
authors.initials: LB
authors.lastname: Young
authors.forename: David B
authors.initials: DB
authors.lastname: Henson
mesh_terms: D000328:Adult; D000368:Aged; D003930:Diabetic Retinopathy / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D017075:Laser Coagulation / Q000379:methods*; D053844:Lasers, Solid-State / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D014786:Vision Disorders / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult