Fluorescein pattern interpretation in keratoconus.
OBJECTIVE
The purpose of this study is to assess the effect of disease severity on how accurately contact lens fluorescein patterns can be interpreted in keratoconus by clinician assessment.


METHODS
Two clinicians evaluated fluorescein patterns on 111 eyes of 60 patients with mild (<45 D, 14 eyes), moderate (45 D to 52 D, 61 eyes,) and severe (>52 D, 36 eyes) keratoconus. The masked clinicians were given six contact lenses in random order, the lens that just cleared the corneal apex (the first definite apical clearance lens), three lenses flatter (in 0.1 mm increments), and two lenses steeper (in 0.1 mm increments) than the first definite apical clearance lens. They ranked the lenses from flattest to steepest, based on the fluorescein patterns. The percentage of lenses correctly ranked was determined using (1) exact match with actual; (2) within 0.1 mm of actual; and (3) within 0.2 mm of actual. Accuracy was assessed as the sum of the squared differences between the actual base curve value and each clinician's ranking. Comparison of the mean percentage correctly ranked and accuracy for each keratoconus severity groups was performed using a mixed linear model.


RESULTS
Neither percentage correctly ranked (using any of the three protocols) nor accuracy was found to be related to severity of keratoconus (p > 0.15 for all comparisons).


CONCLUSIONS
Accuracy of ranking contact lenses in order of base curve radius based on fluorescein pattern assessment by clinicians does not seem to be related to severity of keratoconus. Many factors influence interpretation of fluorescein patterns including all components of the system, fluorescein, tears, cornea, contact lens, external forces, and technique.
Fink
Barbara
B
The Ohio State University College of Optometry, 320 West Tenth Avenue, Columbus, OH 43210-1240, USA. fink.4@osu.edu
Heard
Cynthia
C
Schafer
Jeff
J
Cline
Ame Richardson
AR
Mitchell
Lynn
L
Barr
Joseph T
JT
D000328:Adult; D000368:Aged; D003261:Contact Lenses; D003315:Cornea / Q000378:metabolism* / Q000473:pathology; D019781:Corneal Topography; D005260:Female; D019793:Fluorescein / Q000493:pharmacokinetics*; D005456:Fluorescent Dyes / Q000493:pharmacokinetics*; D006801:Humans; D007640:Keratoconus / Q000378:metabolism* / Q000473:pathology* / Q000534:rehabilitation; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D016037:Single-Blind Method
D005456:Fluorescent Dyes; D019793:Fluorescein