Relationship between corneal biomechanical properties, central corneal thickness, and intraocular pressure across the spectrum of glaucoma.
OBJECTIVE
To evaluate corneal biomechanical properties across the glaucoma spectrum and study the relationship between these measurements and intraocular pressure measured by Goldmann applanation tonometry (GAT-IOP) and central corneal thickness (CCT).


METHODS
Prospective cross-sectional study.


METHODS



METHODS
Tertiary-care teaching institute.


METHODS
A total of 323 eyes of 323 participants (71 normal, 101 glaucoma suspect [GS], 38 ocular hypertension [OHT], 59 primary angle-closure disease [PACD], 36 primary open-angle glaucoma [POAG], and 18 normal-tension glaucoma [NTG]) who had received no ophthalmic treatment.


METHODS
Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) measured by the Ocular Response Analyzer (ORA). GAT-IOP and CCT recorded in all subjects.


METHODS
Regression analysis used to determine the relationship between GAT-IOP, CCT, age, CRF, and CH. Bland-Altman plots used to assess agreement between IOP measured by GAT and the ORA (IOPg).


RESULTS
CH measurements were significantly less in POAG and NTG compared to normal subjects (P = .034 and P = .030 respectively), regardless of the IOP. The CRF was significantly less in NTG and maximum in POAG and OHT. Regression analysis with CH as dependant variable showed significant association with GAT-IOP and CRF (P < .001) but not CCT, persisting on multivariate analysis (adjusted R(2) = 0.483). GAT-IOP correlated strongly with Goldmann-correlated IOP on the ORA (IOPg) (r = 0.82; P < .001), but limits of agreement between the measurements were poor.


CONCLUSIONS
CH and CRF may constitute a pressure-independent risk factor for glaucoma. CRF appears to influence GAT-IOP measurements more than simple geometric thickness measured by CCT. However, IOP measurements from the ORA are not interchangeable with, and are unlikely to replace, Goldmann applanation tonometry at the present time.
Advanced Eye Centre, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Sushmita
S
Kaushik
Surinder Singh
SS
Pandav
Anupam
A
Banger
Kanika
K
Aggarwal
Amod
A
Gupta
D001696:Biomechanical Phenomena; D003315:Cornea / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D004548:Elasticity / Q000502:physiology; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000503:physiopathology*; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000503:physiopathology; D011446:Prospective Studies; D012307:Risk Factors; D014065:Tonometry, Ocular; D014794:Visual Fields