title: Phototherapeutic keratectomy in diffuse stromal haze in granular corneal dystrophy type 2.
abstract: OBJECTIVE
  To determine the minimum depth of phototherapeutic keratectomy (PTK) required for diffuse haze removal in granular corneal dystrophy type 2 and to determine whether Fourier domain optical coherence tomography (FD-OCT) can be an effective technique for predicting the exact required depth of ablation.
  
  
  METHODS
  The depth of ablation used for diffuse stromal haze removal was evaluated with the slit lamp and serially taken photographs during the PTK procedure. The depth of diffuse haze was measured preoperatively using FD-OCT.
  
  
  RESULTS
  Forty-three eyes of 30 patients were included in this study. The mean age of the patients was 62.0 ± 8.4 years. The mean depth of PTK required was 43.7 ± 6.2 μm (range, 31-59 μm). The mean follow-up period for 29 eyes of 22 patients, who had follow-up periods of more than 6 months, was 21.0 ± 12.0 months. The mean best spectacle-corrected visual acuity of these 29 eyes was 0.43 ± 0.15 preoperatively and 0.71 ± 0.16 (P = 0.022) 1 month postoperatively. Of the 43 eyes of 30 patients, FD-OCT was evaluated in 29 eyes of 22 patients. The mean preoperative depth of diffuse haze using FD-OCT was 44.3 ± 6.4 μm. The mean depth of ablation required to remove diffuse stromal haze was 44.5 ± 5.9 μm. The actual ablated depths correlated well with the depth of haze detected by FD-OCT preoperatively (intraclass correlation coefficient = 0.719).
  
  
  CONCLUSIONS
  FD-OCT is an accurate method of predicting the depth of PTK required to remove visually significant diffuse haze in patients with granular corneal dystrophy type 2. We advocate the use of slit-lamp biomicroscopy after the initial 30-μm ablation to determine the necessity for any further ablation.
authors.affiliation: Department of Ophthalmology, Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Se Hwan
authors.initials: SH
authors.lastname: Jung
authors.forename: Kyung Eun
authors.initials: KE
authors.lastname: Han
authors.forename: R Doyle
authors.initials: RD
authors.lastname: Stulting
authors.forename: Bradford
authors.initials: B
authors.lastname: Sgrignoli
authors.forename: Tae-im
authors.initials: TI
authors.lastname: Kim
authors.forename: Eung Kweon
authors.initials: EK
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D003317:Corneal Dystrophies, Hereditary / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D003319:Corneal Stroma / Q000473:pathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D005583:Fourier Analysis; D006801:Humans; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D018903:Photorefractive Keratectomy; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology