Comparison of the ocular wavefront aberration between pharmacologically-induced and stimulus-driven accommodation.
OBJECTIVE
To compare the ocular wavefront aberration between pharmacologically- and stimulus-driven accommodation in phakic eyes of young subjects.


METHODS
The aberration structure of the tested eye when accommodating was measured using the Complete Ophthalmic Analysis System (COAS; AMO WaveFront Sciences, Albuquerque, NM, USA). It was used in conjunction with a purposely-modified Badal optometer to allow blur-driven accommodation to be stimulated by a high contrast letter E with a vergence range between +0.84 D and -8.00 D. Pharmacological accommodation was induced with one drop of pilocarpine 4%. Data from six subjects (age range: 23-36 years) with dark irides were collected.


RESULTS
No correlation was found between the maximal levels of accommodative response achieved with an 8 D blur-driven stimulus and pharmacological stimulation. Pharmacological accommodation varied considerably among subjects: maximum accommodation, achieved within 38-85 min following application of pilocarpine, ranged from 2.7 D to 10.0 D. Furthermore, although the changes of spherical aberration and coma as a function of accommodation were indistinguishable between the two methods for low levels of response, a characteristic break in the pattern of aberration occurred at higher levels of pilocarpine-induced accommodation. This probably resulted from differences in the time course of biometric changes occurring with the two methods.


CONCLUSIONS
Measuring the pilocarpine-induced accommodative response at only one time point after its application may lead to misleading results. The considerable inter-individual differences in the time course of drug-induced accommodative response and its magnitude may lead to overestimation or underestimation of the corresponding amplitude of normal, blur-driven accommodation. Stimulating accommodation by topical application of pilocarpine is inappropriate for evaluating the efficacy of 'accommodating' IOLs.
Institute of Vision and Optics, School of Health Sciences, University of Crete, Heraklion, Crete 71003, Greece. plainis@med.uoc.gr
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Plainis
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Plevridi
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Pallikaris
D000065:Accommodation, Ocular / Q000187:drug effects* / Q000502:physiology; D000328:Adult; D003290:Convergence, Ocular / Q000187:drug effects* / Q000502:physiology; D005123:Eye / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008916:Miotics / Q000494:pharmacology*; D010829:Physiological Phenomena / Q000187:drug effects; D010862:Pilocarpine / Q000494:pharmacology; D012029:Refraction, Ocular / Q000187:drug effects*; D014792:Visual Acuity / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult
D008916:Miotics; D010862:Pilocarpine