EXTENDED REPORT

The effect of human in vivo accommodation on crystalline lens stability

Ronald A Schachar¹, Carlos Davila², Barbara K Pierscionek³, Wickham Chen² and Warren W Ward⁴

¹ Department of Physics, University of Arlington, Arlington, Texas, USA
² Department of Electrical Engineering, Southern Methodist University, Dallas, Texas, USA
³ Department of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
⁴ Fourward Technologies, Buena Vista, Virginia, USA

Correspondence to:
Correspondence to:
Professor R A Schachar
University of Texas at Arlington, PO Box 601149, Dallas, TX 75229, USA; ron{at}2ras.com

Aim: To determine the effect of human in vivo accommodation on the stability of the crystalline lens.

Methods: Using a dual Purkinje image (DPI) eyetracker, the phase–time difference and amplitudes of Purkinje images I (P_I) and IV (P_1V) were measured in 37 normal emmetropic subjects (34 women and 3 men; mean age 19.8, range 18–22 years) when they changed focus from 70 to 15 cm and simultaneously rotated their heads horizontally from side to side or made horizontal saccades between two targets 6.8° apart.

Results: When the subjects changed focus from 70 to 15 cm and rotated their heads or made eye saccades, the phase–time difference between P_I and P_IV decreased. During saccades, the amplitude of both P_I and P_IV overshoots significantly increased with focus at 15 cm; however, their ratio (P_IV overshoot amplitude/P_I overshoot amplitude) significantly declined.

Conclusions: The lens is stable during accommodation. The implications of these findings on the mechanism of accommodation are discussed.

Abbreviations: DPI, dual Purkinje image; P_I, Purkinje image I; P_IV, Purkinje image IV; UBM, ultrasound biomicroscopy

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

• Schachar, R A, Koivula, A (2008). The stress on the anterior lens surface during human in vivo accommodation. Br. J. Ophthalmol. 92: 348-350 [Abstract] [Full Text]