J Korean Ophthalmol Soc.  2009 Nov;50(11):1605-1610.

Factors Affecting the Ocular Response Analyzer Parameters in Normal Korean

• Kim SW
• Seo SG
• Her J
• Park SJ

Abstract

PURPOSE
To identify the normal range of factors which can be measured with Ocular Response Analyzer (ORA, Reichert Inc., Depew, NY, USA) in normal Korean, and to analyze factors affecting ORA by measuring intraocular pressure (IOP) of noncontact tonometer (NCT) and central corneal thickness (CCT).
METHODS
Three hundred and one normal Korean subjects who did not have specific ophthalmological diseases and surgeries in the past were recruited for this study. Corneal hysteresis (CH), corneal response factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann correlated IOP (IOPg) were measured using ORA. In addition, IOP of NCT and CCT were measured and the results and factors analyzed.
RESULTS
The mean CH measured among normal Korean subjects in this study was 10.70 mmHg. The mean CRF was 10.40 mmHg. CH and CRF were significantly higher in the juvenile group. IOPcc and IOPg as measures of IOP using the ORA had significant correlation with IOP of NCT. In particular, IOPcc appeared to be independent of CCT.
CONCLUSIONS
CH and CRF were different according to age, indicating a difference in biomechanical properties of the cornea. In particular, IOPcc is more important as it is independent of corneal thickness and should be compensated in general measurements of IOP reflecting biomechanical properties.

Keyword

Central corneal thickness; Corneal hysteresis; Intraocular pressure; Non contact tonometer; Ocular response analyzer (ORA)

MeSH Terms

Cornea
Intraocular Pressure
Reference Values

Figure

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  Figure 1. The difference between the “inward” applanation and the “outward” applanation is called corneal hysteresis (CH).

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  Figure 2. Demographic data of characterization group.

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  Figure 3. Histogram of corneal compensated IOP measured by Ocular Response Analyzer (IOPcc) and non contact tonometer (NCT) for normal eyes.

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  Figure 4. Statistical correlations between parameters (Pearson correlation test). The yellow squares indicate significance with a high level of correlation, r≥±0.7. The blue squares indicate significance with a moderate correlation, r≥±0.4. The gray squares indicate statically not significance with correlation, p>0.05.(CH=corneal hysteresis; CRF=corneal resistance factor; IOPcc=corneal compensated IOP; IOPg=Goldmann-correlated IOP; CCT=central corneal thickness; NCT=non contact tonometer)

Reference

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