Wavefront aberrations and the depth of focus of the human eye

摘要: The depth of focus (DOF) can be defined as the variation in image distance a lens or an optical system which tolerated without incurring objectionable lack sharpness focus. DOF human eye serves mechanism blur tolerance. As long target remains within space, will still perceive being clear. A large is especially important for presbyopic patients with partial complete loss accommodation (presbyopia), since this helps them to obtain acceptable retinal when viewing moving through range near intermediate distances. aim research was investigate and its association natural wavefront aberrations, how higher order aberrations (HOAs) used expand DOF, particular by inducing spherical ( 0 4 Z 6 ). measured using variety subjective objective methods. Subjective measurements based on Badal have been widely adopted, size kept constant. In such measurements, subject.s tested normally cyclopleged. Objective methods need cycloplegia are also used, where eye.s accommodative response continuously monitored. Generally, slightly larger than those objectively. recent years, developed estimate from quality metrics (IQMs) derived ocular aberrations. methods, defocus error that degrades calculated IQMs certain level possible maximum value. study, effect different amounts HOAs theoretically evaluated modelling comparing subjects four clinical groups, including young emmetropes (20 subjects), myopes (19 presbyopes (32 subjects) keratoconics (35 subjects). novel IQM-based through-focus algorithm predict their HOAs. Additional primary aberration ) induced wavefronts simulate myopic refractive correction (e.g. LASIK) progressive power IOL) DOF. Larger were found lead greater values predicted introduction provide moderate increase while deteriorating at same time. affected threshold adopted. We then investigated influence chosen it relates subjectively group 17 normal subjects, we visual Strehl ratio transfer function (VSOTF) IQM results allowed comparison estimated determination estimation. Significant correlation between HOA RMS (Pearson.s r=0.88, p<0.001). linear each individual subject, subsequently leading method estimating individual.s single measurement subsequent study conducted keratoconic subjects. increases HOAs, aberration, coma trefoil, observed eyes. This population provides opportunity these It expected asymmetric (coma trefoil) could interact cause regional target. dual-Badal-channel star-pattern measure 10 eyes compared significantly However there not strong amount Among all terms, only helped studied Through first three studies, comprehensive understanding had achieved. An adaptive optics designed constructed. capable measuring altering resulting under combination Using AO system, concept extending optimized combinations . Systematic targeted both improve healthy use opposite signs further rather alone. optimal VSOTF. experiment, better balance expansion relatively smaller decreases VA. Therefore, more efficient PhD has shown positive More aberrated generally quantified, allows estimation directly aberration. Zernike Certain effective alone, useful design corrections multifocal contact lenses, intraocular lenses laser corneal surgeries.