Correlations between corneal hysteresis, intraocular pressure, and corneal central pachymetry.
OBJECTIVE
To analyze the correlation between corneal hysteresis (CH) measured with the Ocular Response Analyzer (ORA, Reichert) and ultrasonic corneal central thickness (CCT US) and intraocular pressure measured with Goldmann applanation tonometry (IOP GA).


METHODS
Bordeaux 2 University, Ophthalmology Department, Bordeaux, France.


METHODS
This study comprised 498 eyes of 258 patients. Corneal hysteresis, corneal resistance factor (CRF), and IOP corneal-compensated (IOPcc) were provided by the ORA device; CCT US and IOP GA were also measured in each eye. The study population was divided into 5 groups: normal (n = 122), glaucoma (n = 159), keratoconus (n = 88), laser in situ keratomileusis (LASIK) (n = 78), and photorefractive keratectomy (n = 39). The Pearson correlation was used for statistical analysis.


RESULTS
Corneal hysteresis was not strongly correlated with IOP or CCT US. The mean CH in the LASIK (8.87 mm Hg) and keratoconus (8.34 mm Hg) groups was lower than in the glaucoma (9.48 mm Hg) and normal (10.26 mm Hg) groups. The lower the CH, the lower its correlation with IOPcc and IOP GA. A CH higher than the CRF was significantly associated with the keratoconus and post-LASIK groups.


CONCLUSIONS
Corneal hysteresis, a new corneal parameter, had a moderate dependence on IOP and CCT US. Weaker corneas could be screened with ORA parameters, and low CH could be considered a risk factor for underestimation of IOP. The CCT US should continue to be considered a useful parameter.
Touboul
David
D
Department of Ophthalmology, Bordeaux 2 University, CHU Pellegrin, Place Amélie Raba-Léon, Bordeaux, France. toubould@gmail.com
Roberts
Cynthia
C
Kérautret
Julien
J
Garra
Caroline
C
Maurice-Tison
Sylvie
S
Saubusse
Elodie
E
Colin
Joseph
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003315:Cornea / Q000503:physiopathology* / Q000601:surgery / Q000648:ultrastructure; D004547:Elastic Tissue / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004548:Elasticity; D005260:Female; D005901:Glaucoma / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D007640:Keratoconus / Q000503:physiopathology; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D018903:Photorefractive Keratectomy; D011446:Prospective Studies; D014065:Tonometry, Ocular