title: Influence of eyelid position on wavefront aberrations.
abstract: OBJECTIVE
  To investigate the influence of eyelid position on wavefront aberrations.
  
  
  METHODS
  In study 1, the right eyes of 43 non-cyclopleged subjects were evaluated using the Complete Ophthalmic Analysis System (COAS) aberrometer. In study 2, the right eyes of the 23 cyclopleged subjects were evaluated using the Optical Pathway Difference Scan aberrometer. Measurements were made with wide-open and deliberately narrowed palpebral apertures in these subjects. In study 3, the influence of eyelashes on the COAS output was investigated in 20 subjects by placing artificial eyelashes in front of the eye, in close proximity to the natural eyelashes.
  
  
  RESULTS
  For study 1, the total root mean square (RMS) of the third- and fourth-order aberrations with the wide-open lids was significantly different from the narrowed lid position after the correction for multiple comparisons. There was a difference in the Zernike coefficient of the defocus (C4), 90/180 astigmatism (C5), vertical coma (C7) and spherical aberration terms (C12) between the narrowed and wide-open positions. For study 2, changes were observed with the narrowed lid position in the overall RMS of the third and fourth orders, and total coma aberrations, as well as the specific Zernike coefficients of the C5 and C7 terms. However, none of these changes were significant after the multiple comparison correction. The corneal topography also showed remarkable changes in the superior corneal zone. Placing artificial eyelashes in front of the eye significantly affected some Zernike terms and the RMS of the second and fourth orders, and total coma aberrations, for particular pupil sizes.
  
  
  CONCLUSIONS
  Deliberate narrowing of the palpebral aperture can influence the wavefront aberrations significantly. The corneal curvature distortion in response to eyelid pressure may account for some of the effect on aberration change. Eyelashes interfering with the light path within the pupil zone distort the output from the COAS, causing significant errors.
authors.affiliation: Department of Ophthalmology, The First Affiliated Hospital, Medical College, Zhejiang University, Hangzhou, China. hanweidr@hotmail.com
authors.forename: Wei
authors.initials: W
authors.lastname: Han
authors.forename: William
authors.initials: W
authors.lastname: Kwan
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Shea Ping
authors.initials: SP
authors.lastname: Yip
authors.forename: Maurice
authors.initials: M
authors.lastname: Yap
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology*; D016022:Case-Control Studies; D019781:Corneal Topography; D005140:Eyelashes; D005143:Eyelids / Q000502:physiology*; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000502:physiology; D008297:Male; D009184:Mydriatics / Q000008:administration & dosage; D011312:Pressure; D012029:Refraction, Ocular
chemical_list: D009184:Mydriatics