Relationship between contrast sensitivity and spherical aberration: Comparison of 7 contrast sensitivity tests with natural and artificial pupils in healthy eyes
Received 14 July 2008; received in revised form 16 September 2008; accepted 21 September 2008.
Purpose
To find a contrast sensitivity test that can be used clinically to evaluate interventions aimed at minimizing spherical aberration and determine the circumstances under which these tests should be performed.
Setting
Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands.
Methods
Contrast sensitivity tests were performed using 2 experimental designs. Design 1 was with a natural pupil under mesopic and photopic conditions. Design 2 was with a 5.0 mm artificial pupil after cycloplegia under photopic conditions only. Two computerized tests (vertical sine-modulated gratings [VSG] and Holladay circular sine-modulated patterns [HACSS]) and 5 chart tests (Pelli-Robson, acuity-measuring letter charts at low contrast [2.5% and 10%], VectorVision, and edge contrast sensitivity) were used. Spherical aberration was assessed with a Hartmann-Shack wavefront analyzer.
Results
Forty-nine healthy subjects aged 20 to 35 years (n = 24) and 55 to 70 years (n = 25) participated. Design 2 showed a significant relationship between contrast sensitivity and spherical aberration with the HACSS at 3 cycles per degree (cpd) (P = .03) and 6 cpd (P = .01) and with the VSG at 6 cpd (P = .01). Design 1 yielded no significant relationships.
Conclusions
Using an artificial pupil, a relationship between contrast sensitivity and spherical aberration was established with the VSG and HACSS tests but not with the chart tests. No test showed a relationship using natural pupils under either lighting condition. Chart tests are unsuitable for uncovering contrast sensitivity differences related to differences in spherical aberration, as typically found in healthy phakic eyes.
From the Laboratory of Experimental Ophthalmology (van Gaalen, Kooijman) and Department of Ophthalmology (Jansonius, Koopmans), University Medical Center Groningen, University of Groningen, and Advanced Medical Optics Groningen BV (Terwee), Groningen, the Netherlands
Corresponding author: K.W. van Gaalen, MSc, Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Postbus 30.001, 9700 RB, Groningen, The Netherlands.
Dr. Terwee is an employee of Advanced Medical Optics Groningen BV, The Netherlands. No other author has a financial or proprietary interest in any material or method mentioned.
Presented at the annual meeting of the Association for Research in Vision and Ophthalmology, Fort Lauderdale, Florida, USA, May 2007.
Supported by SenterNovem, The Hague, The Netherlands, and Dutch National Grant ISO43081.
ABSTRACT