The Effects of Age and Diabetes on Corneal Hysteresis and Corneal

Resistance Factor

Irene C. Kuo, MDAssociate Professor of Ophthalmology

Wilmer Eye Institute

The authors have no financial interest in the subject matter of this poster

Kuo, Boston 2010

Co-authors

• Jonathan Tzu, MD

• Alisa Kim, MD

• Aimee T. Broman, MA

Introduction

• As viscoelastic tissue, cornea can be described by static resistance component and dynamic resistance component

• Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, NY) measures intraocular pressure and corneal hysteresis, presumably measure of dynamic component.

Kuo, Boston 2010

Introduction

• Aldehydes can induce enzymatic cross-linking

• Moreover, our group has found a negative association between diabetes (DM) and keratoconus (Kuo et al, Ophthalmology 2006)

• Other groups have reported that diabetic patients have higher corneal hysteresis (Hager et al, Graefes Arch Clin Exp Ophthalmol 2009; Goldich et al, J Cataract Refract Surg 2009)

Kuo, Boston 2010

Purpose

• Does diabetes have an effect on corneal hysteresis measurements (CH) and corneal resistance factor (CRF) in patients seen in a glaucoma clinic, where measurements using the ORA were obtained as part of a previous study?

Kuo, Boston 2010

Patients and Methods

• consecutive patients seen in Glaucoma Clinic between 12/2/03 and 8/25/04– Hysteresis measurements were obtained on

pts aged 18 and over who had not had surgery in prior 90 days

• Hypothesis: CH is predicted by age, gender, race, central corneal thickness (CCT), edema, DM

Kuo , Boston 2010

Statistical Methods

• Each eye was measured twice by ORA, and average was recorded

• CH was modeled in multiple regression model with age, gender, age, DM status, CCT, and edema. – Measurements for each eye were entered in the regression

– Generalized Estimating Equations were used to account for correlation between eyes

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Results

• 452 eyes of 228 pts• 56% were female• 34 (15%) patients were diabetic• No difference between diabetic and

nondiabetic patients in age or sex • CH was 0.69 mm Hg and CRF was 0.94 mm

Hg in diabetic pts than in non-diabetic pts (p=0.02 and p=0.01, respectively), adjusting for age, gender, CCT, and edema

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Table 1Predictors of corneal hysteresis measurements, using multiple regression with

repeated measures; correlation between eyes was 0.37.

Estimate SE P-value

Age (per year) −0.02 0.009 0.02Gender Female −0.008 0.22 0.97Race Caucasian (reference) 0.0 - -

Africa -n American −0.30 0.32 0.35Other −0.25 0.35 0.47

Diabetes presence 0.69 0.27 0.01Cornea l Thickness (per 10 μ )m 1.50 0.32 <0.0001

Kuo, Boston 2010

Table 2Predictors of corneal resistance factor measurements, using

multiple regression with repeated measures.

Estimate SE P-value

Age (per year) -0.05 0.01 <0.0001

Gender Female 0.11 0.31 0.71

Race Caucasian (reference) 0.0 - -

African-American -0.98 0.41 0.02

Other -0.64 0.52 0.21

Diabetes Presence 0.94 0.39 0.02

Corneal thickness (per 10 μ )m 0.029 0.0067 <0.0001

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Conclusions

• Diabetic pts in a glaucoma clinic had higher CH and CRF than did non-diabetic pts, adjusting for age, race, gender, CCT, and corneal edema

• Results may reflect changes in corneal structure and biomechanics as a result of collagen cross-linking induced by hyperglycemia

• There was no association between DM and CCT• Age was associated with decreased CH

Kuo, Boston 2010

Conclusions

• Age and DM induce changes in corneal biomechanical properties, but had opposite effects on CH.

• What is the most appropriate parameter by which to measure mechanical properties of viscoelastic structure like the cornea?– CH?– Ocular rigidity?– Other?

Kuo , Boston 2010