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McWhae and Reimer believe that the iris plays a role in accommodation. A prior UBM study undertaken by McWhae, Crichton and Reimer1McWhae J.A. Crichton A.C.S. Reimer J. A dynamic study of accommodation using ultrasound biomicroscopy.in: Cennamo G. Ultrasonography in Ophthalmology XV Proceedings of the 15th SIDUO Congress, Cortina, Italy, 1994. Kluwer, Dortrecht1997: 233-240Crossref Google Scholar demonstrated a posterior bowing of the human iris with accommodation, possibly suggesting a role for the iris in primate accommodation. McWhae and Reimer refer to a reference in Glasser and Kaufman2Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (264) Google Scholar which shows that accommodative amplitude is reduced after iris removal in primates and from this they infer that Glasser and Kaufman2Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (264) Google Scholar suggest that the iris may play a role in primate accommodation. Crawford, Kaufman and Bito3Crawford K.S. Kaufman P.L. Bito L.Z. The role of the iris in accommodation of rhesus monkeys.Invest Ophthalmol Vis Sci. 1990; 31: 2185-2190PubMed Google Scholar found that maximum pharmacologically induced accommodative amplitude was 40% lower in iridectomized rhesus monkeys than in uniridectomized controls. However, they also found that neither submaximal accommodative amplitude achieved through intramuscular pilocarpine injection nor maximal accommodation induced by central brain stimulation differed in iridectomized versus uniridectomized controls. The implications of this study are that when supramaximal doses of pharmacological cholinergic agonists are delivered to the eye, an unnaturally high accommodative response occurs. Since the iris is extremely responsive to cholinergic stimulation, the supramaximal accommodative response was attributed to the unusually strong pupillary constriction serving to pull the ciliary muscle centripetally to a greater extent than would normally occur with accommodation. More physiologically realistic accommodative amplitudes, such as achieved through stimulation of the central accommodative pathways, are not diminished in iridectomized eyes. The findings of Glasser and Kaufman2Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (264) Google Scholar that similar accommodative responses were observed in iridectomized and noniridectomized monkeys indicates, as stated, that the fundamental accommodative mechanism is unlikely to be altered by the removal of the iris. We have no evidence to suggest that any aspect of the normal accommodative function is altered with removal of the iris. With regard to the posterior bowing of the iris1McWhae J.A. Crichton A.C.S. Reimer J. A dynamic study of accommodation using ultrasound biomicroscopy.in: Cennamo G. Ultrasonography in Ophthalmology XV Proceedings of the 15th SIDUO Congress, Cortina, Italy, 1994. Kluwer, Dortrecht1997: 233-240Crossref Google Scholar that is evident in Glasser and Kaufman2Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (264) Google Scholar figure 4, this is as likely to be a secondary consequence of accommodation as it is to be an active component of it. Forward bulging of the anterior lens surface into the anterior chamber centrally would force aqueous humor to the periphery, bowing the iris backward. Such fluid pressure and backward bowing of the iris would seem unlikely to provide active support for the peripheral lens in maintaining an accommodated state, since the lens has a natural tendency to take on an accommodated form when zonular tension is released due to the elastic forces of the capsule.4Glasser A. Campbell M.C. Presbyopia and the optical changes in the human crystalline lens with age.Vision Res. 1998; 38: 209-229Crossref PubMed Scopus (460) Google Scholar, 5Glasser A. Campbell M.C. Biometric, optical and physical changes in the isolated human crystalline lens with age in relation to presbyopia.Vision Res. 1999; 39: 1991-2015Crossref PubMed Scopus (314) Google Scholar We thank the authors for their commendation of our work, their observation of the posterior bowing of the iris,1McWhae J.A. Crichton A.C.S. Reimer J. A dynamic study of accommodation using ultrasound biomicroscopy.in: Cennamo G. Ultrasonography in Ophthalmology XV Proceedings of the 15th SIDUO Congress, Cortina, Italy, 1994. Kluwer, Dortrecht1997: 233-240Crossref Google Scholar and the opportunity to comment on their prior findings. We concur with their statement of the importance in fully understanding the accommodative mechanism in light of the development of surgical procedures designed to restore accommodation. We add that it should be the responsibility of those undertaking or advocating these surgical procedures to understand the accommodative mechanism and the overall ocular impact of these invasive surgical procedures before undertaking them. Detail of a Lithograph Print from Vanity Fair Magazine, 1870. “The Statesman/A Promising Apprentice.” Characterization wearing a monocle. Courtesy of the Museum of Ophthalmology, Foundation of the American Academy of Ophthalmology, San Francisco.