title: Saccadic lens instability increases with accommodative stimulus in presbyopes.
abstract: An SRI dual Purkinje image (dPi) eye tracker was used to measure lens wobble following saccades with increasing accommodative effort as an indirect measure of ciliary muscle function in presbyopes. Ten presbyopic subjects executed 32 four-degree saccades at 1-s intervals between targets arranged in a cross on illuminated cards at each of 9 viewing distances ranging from 0.5- to 8-D accommodative demands. Post-saccadic lens wobble artifacts were extracted by subtraction of P1 (H(1)/V(1)) position signals from P4 signals (Theta(H)/Theta(V)), both of which were sampled by the eye tracker at 100 Hz. A ray tracing eye model was also employed to model the fourth Purkinje image shifts for a range of lens translations and tilts. Combining all saccades from all subjects showed a significant positive relationship between lens wobble artifact amplitude and accommodative demand. Eye model simulations indicated that artifacts of the amplitude measured could arise from either lens tilts (in the range of 2-4 degrees) or lens translations (in the range of 0.1 to 0.2 mm). Saccadic lens wobble artifacts increase with accommodative effort in presbyopes, indicating preserved ciliary muscle function and greater relaxation of zonular tension with accommodative effort. Variation across subjects may reflect differences in accommodative effort, ciliary muscle function for a given effort, and/or in intraocular anatomy.
authors.affiliation: College of Optometry, University of Houston, 4901 Calhoun Road, Houston, TX 77204, USA. lhe.2011@alumni.opt.uh.edu
authors.forename: Lin
authors.initials: L
authors.lastname: He
authors.forename: William J
authors.initials: WJ
authors.lastname: Donnelly
authors.forename: Scott B
authors.initials: SB
authors.lastname: Stevenson
authors.forename: Adrian
authors.initials: A
authors.lastname: Glasser
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000368:Aged; D000375:Aging / Q000502:physiology; D016477:Artifacts; D002386:Cataract / Q000503:physiopathology*; D003290:Convergence, Ocular / Q000502:physiology; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009184:Mydriatics; D010775:Photic Stimulation; D011305:Presbyopia / Q000503:physiopathology*; D011680:Pupil / Q000502:physiology; D012438:Saccades / Q000502:physiology*; D014741:Video Recording
chemical_list: D009184:Mydriatics
references.citation: Invest Ophthalmol Vis Sci. 1999 May;40(6):1162-9
references.pmid: 10235549
references.citation: J Refract Surg. 2000 Sep-Oct;16(5):S659-60
references.pmid: 11019895
references.citation: J Physiol. 1977 Apr;266(2):471-98
references.pmid: 857007
references.citation: Graefes Arch Clin Exp Ophthalmol. 2007 Sep;245(9):1357-66
references.pmid: 17285335
references.citation: Exp Eye Res. 2005 Mar;80(3):425-34
references.pmid: 15721624
references.citation: Mol Vis. 2007 Feb 23;13:252-7
references.pmid: 17356512
references.citation: J Cataract Refract Surg. 2006 Nov;32(11):1792-8
references.pmid: 17081859
references.citation: Exp Eye Res. 2008 May;86(5):746-52
references.pmid: 18342856
references.citation: Exp Brain Res. 1982;45(1-2):45-58
references.pmid: 7056337
references.citation: Exp Neurol. 1975 Jul;48(1):107-22
references.pmid: 1132465
references.citation: Exp Brain Res. 1986;61(2):386-94
references.pmid: 3948945
references.citation: Comput Programs Biomed. 1975 Aug;4(4):230-6
references.pmid: 1175371
references.citation: J Physiol. 1988 Oct;404:183-97
references.pmid: 3253430
references.citation: Mech Ageing Dev. 1992 Feb;62(2):209-21
references.pmid: 1569790
references.citation: Ophthalmology. 1999 May;106(5):863-72
references.pmid: 10328382
references.citation: J Opt Soc Am. 1973 Aug;63(8):921-8
references.pmid: 4722578
references.citation: Vision Res. 1995 Feb;35(4):529-38
references.pmid: 7900293
references.citation: Vision Res. 1998 Jan;38(2):209-29
references.pmid: 9536350
references.citation: Optom Vis Sci. 2009 Jun;86(6):677-84
references.pmid: 19417700
references.citation: Vision Res. 1999 Jun;39(11):1991-2015
references.pmid: 10343784
references.citation: Trans Am Ophthalmol Soc. 1922;20:132-57
references.pmid: 16692582
references.citation: Optom Vis Sci. 2001 Jun;78(6):417-24
references.pmid: 11444631
references.citation: J Physiol. 1955 Apr 28;128(1):99-112
references.pmid: 14368577
references.citation: Ophthalmic Physiol Opt. 1987;7(2):149-52
references.pmid: 3658438
references.citation: Br J Ophthalmol. 2007 Jun;91(6):790-3
references.pmid: 17215266
references.citation: J Refract Surg. 2008 Nov;24(9):976-83
references.pmid: 19044244
references.citation: J Physiol. 1988 Oct;404:157-82
references.pmid: 3253429
references.citation: Appl Opt. 1978 Mar 1;17(5):691-705
references.pmid: 20197858
references.citation: Graefes Arch Clin Exp Ophthalmol. 2002 Nov;240(11):906-12
references.pmid: 12486512
references.citation: IEEE Trans Biomed Eng. 1963 Oct;10:137-45
references.pmid: 14121113
references.citation: Mol Vis. 2004 Dec 16;10:956-63
references.pmid: 15616482
references.citation: Am J Optom Physiol Opt. 1984 Feb;61(2):133-8
references.pmid: 6703009
references.citation: Acta Ophthalmol. 2008 Sep;86(6):642-7
references.pmid: 18752516
references.citation: Appl Opt. 1985 Feb 15;24(4):527
references.pmid: 18216982