Person:
López Gil, Norberto

Profile Picture
Name
López Gil, Norberto
publication.page.department
Universidad de Murcia. Departamento de Física
Repository logoRepository logoRepository logoRepository logoRepository logo

Filters

2008 - 20093
3
3
Reset filters

Settings

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Publication
    Restricted
    Effect of 3rd-order aberrations on human vision
    (Lippincott, Williams & Wilkins , 2008-08) Fernández Sánchez, Vicente; Ponce, Eugenia M.; Lara Lacárcel, Francisco; Montés Micó, Robert; Castejón Mochón, José Francisco; López Gil, Norberto; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica
    PURPOSE: To investigate the effect of 3rd-order aberrations on human vision. SETTING: Grupo de Ciencias de la Visio´n, University of Murcia, Murcia, Spain. METHODS: The 3rd-order aberrations coma and trefoil were induced with purpose-designed soft contact lenses, 3 inducing coma (low [0.05 mm], medium [0.13 mm], high [1.03 mm]) and 3 inducing trefoil (low [0.07 mm], medium [0.17 mm], high [0.96 mm]). Monocular high-contrast (HCVA) and low-contrast (LCVA) visual acuities and contrast sensitivity were measured in 11 subjects wearing contact lenses with a 5.0 mm artificial pupil. RESULTS: The reduction in HCVA and LCVA was statistically significant only for the highest coma and trefoil values (P<.0001). For coma, the mean change in HCVA was 0.193 logMARG0.100 (SD) and in LCVA, 0.386G0.136 logMAR. For trefoil, it was 0.204G0.128 logMAR and 0.395G0.141 logMAR, respectively. No differences were found for the lower degrees (P>.2). Contrast sensitivity was significantly reduced with the highest coma and trefoil values (P<.0001) (mean change 0.390 G 0.157 and 0.404 G 0.135, respectively). Lower degrees did not cause significant changes in contrast sensitivity (P>.1). The effect of induced coma and trefoil on HCVA, LCVA, and contrast sensitivity was similar at each level of induced aberration (P>.01). CONCLUSIONS: Large values of coma and trefoil (approximately 1 mm) significantly reduced visual performance. Only patients with high 3rd-order aberrations, such as those that occur in refractive surgery or in cases of distorted optics, would benefit from this correction.
  • Thumbnail Image
    Publication
    Open Access
    Accommodation-related changes in monochromatic aberrations of the human eye as a function of age
    (Association for Research in Vision and Ophthalmology (ARVO), 2008-04) López Gil, Norberto; Fernández Sánchez, Vicente; Legras, Richard; Montés Micó, Robert; Lara Lacárcel, Francisco; Nguyen Khoa, Jean Luc; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica
    PURPOSE. To investigate the relationship between accommodation and the optical aberrations of the whole human eye, as a function of age. METHODS. Sixty healthy subjects with spherical ametropia in the range 3 D, astigmatism less than 1 D, corrected visual acuity of 20/18 or better, and normal findings in an ophthalmic examination were enrolled. Subjects were divided into four groups, with age ranges of 19 to 29, 30 to 39, 40 to 49, and 50 to 60 years. Monochromatic optical aberrations and pupil size were measured with a Hartmann-Shack wavefront sensor under monocular viewing conditions, without pharmacological dilation or cyloplegia. Stimulus vergences were in the range of 0 to 5 D, with an increment of 0.5 D. The change in aberration during accommodation for different groups and different pupil conditions (natural and fixed 4-mm pupil) was compared. RESULTS. Fourth-order spherical aberration (SA) became more negative with accommodation, and the rate of this change was greater in older individuals. For natural pupil conditions, there were no significant differences between age groups in the changes of the higher-order aberrations, coma, and trefoil with accommodation. However, for a 4-mm pupil, the youngest and oldest group showed significant differences in higher order RMS (root mean square) and spherical aberration compared with the other groups. High-order RMS showed a lower increase during accommodation when the pupil accommodative miosis was taken into account (natural pupil condition) than when a fixed 4-mm pupil was used. CONCLUSIONS. Aberrations change with accommodation and with age. SA changes more with accommodation do than other higher-order aberrations. SA becomes more negative with accommodation, and this change is larger in older individuals. Accommodative miosis is useful for ameliorating the increase in higher-order aberrations with accommodation.
  • Thumbnail Image
    Publication
    Restricted
    Comparison of partial coherence interferometry and ultrasound for anterior segment biometry
    (Lippincott, Williams & Wilkins, 2009-02) Lara Lacárcel, Francisco; Fernández Sánchez, Vicente; López Gil, Norberto; Cerviño, Alejandro; MCOptom; Montés Micó, Robert; MPhil; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica
    PURPOSE: To assess the performance of a partial coherence interferometry (PCI)–based device for the determination of anterior segment biometry. SETTING: Clinica Centrofama, Cartagena, Murcia, Spain. METHODS: Central corneal thickness (CCT), anterior chamber depth (ACD), and lens thickness (LT) were measured with the ACMaster PCI anterior segment biometer and an Echoscan US-1800 ultrasound (US) biometer/pachymeter with and without cycloplegia. To determine the precision of the instruments, the same examiner took 30 consecutive CCT, ACD, and LT measurements in a single subject under the same conditions and with and without cycloplegia. The same measurements were performed in additional subjects. RESULTS: Twenty-one eyes (16 subjects) were evaluated. Repeated measurements of the single subject yielded a standard deviation of 4.0 mm for CCT, 106.0 mm for ACD, and 323.0 mm for LT; there were many peaks, mainly in the last 10 readings. There was a high correlation between CCT measurements with both systems with and without cycloplegia (r2>0.93), with the US system giving higher values. Differences were significant (P<.001), but not consistent, throughout the range of corneal thicknesses and were greater for thicker corneas. Differences in ACD and LT measurements were similar. Agreement between systems in ACD and LT measurements was considerably lower than for CCT measurements. CONCLUSIONS: The PCI biometer provided precise CCT measurements. The ACD and LT measurements had a higher variance. Differences in CCT measurements between the 2 systems were greater for thicker corneas, with higher values with the US system.
Ir a Estadísticas