Pentacam Scheimpflug tomography findings in topographically normal patients and subclinical keratoconus cases.
OBJECTIVE
To evaluate Pentacam ectasia detection indices in topographically normal patients and in subclinical keratoconus cases.


METHODS
Prospective, observational case series.


METHODS
setting: Institutional. patients: Group 1 comprised 1 eye from 189 patients with unremarkable topography and Groups 2 and 3 included the better and worse eyes, respectively, of 55 keratoconic patients. Group 2 eyes with normal topography (n = 37) were considered subclinical keratoconus cases. observation procedure: Pentacam Scheimpflug tomography. main outcome measures: Eleven Pentacam ectasia detection indices.


RESULTS
All Pentacam ectasia indices significantly differed between Groups 1 and 2 and were correlated with keratoconus grade. Only 99 eyes (52%) in Group 1 had normal values for every index, whereas 7 subclinical keratoconus eyes (19%) showed 2 or fewer abnormal indices. Standardized relational thickness and overall deviation indices had 73% and 89% sensitivity for subclinical keratoconus, respectively. Both average and maximum pachymetric progression indices offered 84% sensitivity while maximum relational thickness index showed 78% sensitivity for subclinical keratoconus. Optimized cutoff values for subclinical keratoconus increased the sensitivity of the standardized and maximum relational thickness indices.


CONCLUSIONS
Pentacam Scheimpflug tomography can detect most subclinical keratoconus cases with unremarkable topography, but performance is not as good as reported and varies considerably for each index. The overall deviation, average and maximum pachymetric progression, and maximum relational thickness indices offer the highest sensitivity, which can be improved by using optimized cutoff values. Specificity constitutes an issue for some indices and up to 10% of subclinical keratoconus cases may go undetected by this technology.
ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina; Ophthalmology Division, Hospital de Clínicas José de San Martín, University of Buenos Aires, Buenos Aires, Argentina.
Pablo R
PR
Ruiseñor Vázquez
ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina; Ophthalmology Division, Hospital de Clínicas José de San Martín, University of Buenos Aires, Buenos Aires, Argentina.
Jonatán David
JD
Galletti
ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina; Ophthalmology Division, Hospital de Clínicas José de San Martín, University of Buenos Aires, Buenos Aires, Argentina.
Natalia
N
Minguez
ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina.
Marianella
M
Delrivo
ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina.
Fernando
F
Fuentes Bonthoux
ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina.
Tomás
T
Pförtner
ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina; Institute of Experimental Medicine, National Academy of Medicine/CONICET, Buenos Aires, Argentina. Electronic address: jeremiasg@gmx.net.
Jeremías Gastón
JG
Galletti
D000293:Adolescent; D000328:Adult; D000368:Aged; D003315:Cornea / Q000473:pathology*; D063171:Corneal Pachymetry; D019781:Corneal Topography / Q000295:instrumentation / Q000379:methods*; D004108:Dilatation, Pathologic / Q000175:diagnosis; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000145:classification / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000379:methods; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity; D014054:Tomography; D055815:Young Adult