Corneal Biomechanical Metrics in Eyes With Refraction of –19.00 to +9.00 D in Healthy Brazilian Patients

Abstract

<h4>PURPOSE</h4><p>To evaluate corneal biomechanical metrics with tomographic parameters (given by the Oculus Pentacam) and refractive data in a population of healthy Brazilian patients.</p> <h4>METHODS</h4><p>Observational, cross-sectional study of 150 consecutive patients (53 men and 97 women; 260 eyes). Age, gender, central keratometric readings (central K), central corneal thickness (CCT), anterior chamber depth (ACD), spherical equivalent refraction, corneal hysteresis, and corneal resistance factor (CRF) were assessed and analyzed. </p> <h4>RESULTS</h4><p>Mean patient age was 46.5±21.04 years, average central K was 43.59±1.54 diopters (D), CCT was 545.05±35.41 µm, ACD was 2.96±0.52 mm, spherical equivalent refraction was –1.16±3.48 D, corneal hysteresis was 10.17±1.82, and CRF was 10.14±1.8 (range: 5.45 to 15.1). Mean CRF and corneal hysteresis were distinct among gender: CRF 10.326 in women and 9.810 in men (<i>P</i>=.0266); corneal hysteresis 10.421 in women and 9.727 in men (<i>P</i>=.0031). A negative correlation was found between both CRF and corneal hysteresis with age (r=–0.1255, <i>P</i>=.0434; and r=–0.2445, <i>P</i>=.0001, respectively). No association was found between CRF and average central K (r=0.0633, <i>P</i>=.3086), ACD (r=–0.0474, <i>P</i>=.4498), or spherical equivalent refraction (r=0.1028, <i>P</i>=.1061). Corneal hysteresis was not associated with age and average central K (r=0.0572, <i>P</i>=.3573), ACD (r=0.0060, <i>P</i>=.9236), or spherical equivalent refraction (r=0.0975, <i>P</i>=.1253). Corneal resistance factor and corneal hysteresis were positively associated with CCT (r=0.5760, <i>P</i>=0; and r=0.4655, <i>P</i>=0, respectively).</p> <h4>CONCLUSIONS</h4><p>Corneal biomechanical metrics of healthy Brazilian patients were associated with CCT, gender, and age. Corneal steepness, ACD, and spherical equivalent refraction did not affect corneal hysteresis and CRF values in the studied population. [<cite>J Refract Surg</cite>. 2008;24:941-945.]</p> <h4>AUTHORS</h4> <p>From Federal University of Sao Paulo (Fontes, Nosé); Fluminense Federal University, Rio de Janeiro (Ambrósio, Alonso, Velarde); and Renato Ambrósio Eye Institute, Rio de Janeiro (Ambrósio, Alonso, Jardim), Brazil.</p> <p>The authors have no proprietary interest in the materials presented herein. Dr Ambrósio is a consultant for Oculus and Reichert.</p> <p>Correspondence: Bruno M. Fontes, MD, Av das Acacias 150 bl 2 apto 1001, Barra da Tijuca, Rio de Janeiro – RJ, 22776-000, Brazil. Tel/Fax: 21 3151 3599; E-mail: <a href="mailto:brunomfontes@terra.com.br">brunomfontes@terra.com.br</a></p> <p>Received: March 15, 2007</p> <p>Accepted: September 19, 2007</p> <p><b>Posted online: April 30, 2008</b></p>

The Relationship between Corvis ST Tonometry and Ocular Response Analyzer Measurements in Eyes with Glaucoma

“…[13,42,43] In the current study, age was not significantly correlated with CH or CRF, however, the age range of our study population was narrower than in previous research (mean ± SD = 63.7 ± 10.1 years old, compared to 57.7 ± 15.1[13], 46.5 ± 21.0[42], and 46.7 ± 19.4[43] years old). This may also explain why fewer CST parameters were related to age (mean±SD = 63.7±10.1 years) in the present study, compared to our previous report (52.1±23.4 years).…”

Evaluation of Corneal Deformation Analyzed with Scheimpflug Based Device in Healthy Eyes and Diseased Ones

“…Corneal biomechanical properties measured with ORA have been widely studied in healthy subjects and in patients affected by different kinds of ocular diseases [2–16], so they have today a role in the diagnosis, follow-up, and management of many of them [7, 9, 11]. Different papers, however, showed that CH and CRF are somehow affected by corneal morphological parameters [2, 10, 13, 14, 17, 18], that is, why new kinds of technologies, like optical coherence tomography, are lately utilized in corneal biomechanical evaluation [19–21]. It would be very important to have an accurate evaluation of corneal biomechanics because it would help us in better managing alterations due to a disease (i.e., keratoconus) or to iatrogenic causes (i.e., refractive surgery); moreover, it would help in better measuring the intraocular pressure (IOP), especially in eyes affected by corneal diseases, since the current gold standard, Goldmann applanation tonometry (GAT), has been largely proven to be affected by corneal properties [6, 9, 12, 22].…”

Corneal Biomechanical Properties of Keratoconic Eyes Following Penetrating Keratoplasty

“…38,39,40,41 Most studies in the literature have reported a strong positive correlation between CH and CRF values and CCT in normal eyes. 38,42,43,44,45,46,47 Unlike these studies, Broman et al 48 observed different CH values in eyes with the same CCT value, which they attributed to the possible influence of other unidentified factors on corneal biomechanical properties.…”

“…20,21 It is conceivable that sex differences in corneal biomechanical properties may vary between different ethnicities, explaining these conflicting results. Our evaluation of sex-based differences in the corneal biomechanical properties of unoperated keratoconus eyes in this study showed that CH and CRF values were higher in women, but that the difference was not statistically significant.…”