June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
Thinnest pachymetry and nasal-temporal asymmetry in myopia and emmetropia by Pentacam
Author Affiliations & Notes
  • Sven Jonuscheit
    Vision Sciences, Dept. of Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
    Institute for Applied Health Research, Glasgow Caledonian University, Glasgow, United Kingdom
  • Michael J Doughty
    Vision Sciences, Dept. of Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
  • Raul Martin
    Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, Valladolid, Spain
    Instituto Universitario de Oftalmobiología Aplicada (IOBA Eye Institute), Universidad de Valladolid, Valladolid, Spain
  • Ana Rio-Cristobal
    Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, Valladolid, Spain
    Instituto Universitario de Oftalmobiología Aplicada (IOBA Eye Institute), Universidad de Valladolid, Valladolid, Spain
  • Footnotes
    Commercial Relationships Sven Jonuscheit, None; Michael Doughty, None; Raul Martin, None; Ana Rio-Cristobal, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 1622. doi:
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      Sven Jonuscheit, Michael J Doughty, Raul Martin, Ana Rio-Cristobal; Thinnest pachymetry and nasal-temporal asymmetry in myopia and emmetropia by Pentacam. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1622.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To assess the association between thinnest point pachymetry and nasal-temporal asymmetry in healthy Caucasian individuals with myopia and emmetropia.

 
Methods
 

One hundred and four healthy prepresbyopic subjects (49 myopes, 55 emmetropes) were assessed using the Pentacam Scheimpflug system. One eye per subject and the mean of two measurements were used for analysis. Corneal thickness was extracted from topographic maps including the apex (CCT) and peripheral nasal and temporal points up to 5 mm away from the centre. Thinnest pachymetry (TP) was recorded and the apex-to-thinnest-pachymetry difference (ATD) and apex-to-thinnest ratio (ATR) generated. Absolute nasal-temporal pachymetry differences (NTD) were calculated by subtracting temporal from corresponding nasal values. The relative peripheral asymmetry was expressed as the nasal-temporal ratio (NTR) between corresponding locations. Simple linear regression was used to assess the relationship between ATR and nasal-temporal asymmetry for all as well as myopic and emmetropic eyes.

 
Results
 

The mean age of all subjects was 24±6 years. The mean spherical equivalent was -1.43±1.95 D for all subjects, and -3.05±1.75 D and 0.01±0.19 D for the myopic and emmetropic sub-groups respectively. CCT averaged 554±32 µm and TP 550±32 µm, with a mean ATD of 4.51±2.24 µm and an ATR of 1.008±0.004. Corneal thickness increased asymmetrically with increasing distance from the apex, with a mean NTD of 58±22 µm and a mean NTR of 1.087±0.034 (at 4 mm from apex). Thinnest pachymetry was related to apex thickness (r=0.998, p<0.001). ATR was associated with NTR (r=0.485, p<0.001) and ATD with NTD (r=0.466, p<0.001). These relationships were noted for both groups of myopic and emmetropic eyes (p<0.001).

 
Conclusions
 

In normal corneas without focal thinning the difference and the ratio between apex and thinnest pachymetry are related to the nasal-temporal asymmetry. Further studies on eyes with progressive central or peripheral thinning would be useful to investigate the theory whether peripheral asymmetry is a potential driver for corneal thinning disorders and whether relationships exist between anterior and posterior segment asymmetry.

 
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