Natural history of corneal haze after collagen crosslinking for keratoconus and corneal ectasia: Scheimpflug and biomicroscopic analysis.
OBJECTIVE
To determine the natural history of collagen crosslinking (CXL)-associated corneal haze measured by Scheimpflug imagery and slitlamp biomicroscopy in patients with keratoconus or ectasia after laser in situ keratomileusis.


METHODS
Cornea and refractive surgery subpecialty practice, United States.


METHODS
Prospective randomized controlled clinical trial.


METHODS
The treatment group received ultraviolet-A/riboflavin CXL therapy. The control group received riboflavin alone without epithelial debridement. To objectively measure CXL-associated corneal haze, corneal densitometry using Scheimpflug imagery was measured and the changes in haze were analyzed over time. A similar analysis was performed using clinician-determined slitlamp haze. Correlation of CXL-associated corneal haze with postoperative outcomes was analyzed.


RESULTS
The mean preoperative corneal densitometry was 14.9 ± 1.93 (SD) (Pentacam Scheimpflug densitometry units). Densitometry peaked at 1 month (mean 23.4 ± 4.40; P<.001), with little change at 3 months (mean 22.4 ± 4.79; P = .06) and decreased between 3 months and 6 months (19.4 ± 4.48; P<.001) and between 6 months and 12 months. By 12 months, densitometry had not completely returned to baseline in the entire cohort (mean 17.0 ± 3.82; P<.001) and the keratoconus subgroup; however, it returned to baseline in the ectasia group (16.1 ± 2.41; P = .15). The postoperative course of slitlamp haze was similar to objective densitometry measurements. Increased haze, measured by densitometry, did not correlate with postoperative clinical outcomes.


CONCLUSIONS
The time course of corneal haze after CXL was objectively quantified; it was greatest at 1 month, plateaued at 3 months, and was significantly decreased between 3 months and 12 months. Changes in haze did not correlate with postoperative clinical outcomes.
Cornea and Laser Eye Institute-Hersh Vision Group, CLEI Center for Keratoconus, Teaneck, New Jersey, USA.
Steven A
SA
Greenstein
Kristen L
KL
Fry
Jalpa
J
Bhatt
Peter S
PS
Hersh
D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000378:metabolism*; D003318:Corneal Opacity / Q000175:diagnosis* / Q000503:physiopathology; D003319:Corneal Stroma / Q000378:metabolism* / Q000473:pathology; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D003941:Diagnostic Techniques, Ophthalmological; D004108:Dilatation, Pathologic / Q000188:drug therapy / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000378:metabolism; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D010781:Photography; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011183:Postoperative Complications; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D013997:Time Factors; D014466:Ultraviolet Rays; D014792:Visual Acuity; D055815:Young Adult
D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin