Background. To investigate the correlation between corneal biomechanics and the surgically induced corneal high-order aberrations (HOAs) after small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK). Methods. A total of 150 right myopic eyes that underwent SMILE or FS-LASIK surgery were included in this retrospective study, 75 eyes in each group. The ...

PURPOSE To determine the 1-year changes of mesopic higher order aberrations (HOAs) and contrast sensitivity (CS) after accelerated corneal cross linking (CXL) in progressive keratoconus. METHODS In this prospective case series, 70 eyes of 62 keratoconic patients underwent accelerated CXL (18 mW/cm2, 5 min). HOAs and CS were measured using the OPD Scan III and CSV-1000 CS test charts under mes...

Changes in corneal optics have been measured after downward gaze. However, ocular aberrations during downward gaze have not been previously measured. A commercial Shack-Hartmann aberrometer (COAS-HD) was modified by adding a relay lens system and a rotatable beam splitter to allow on-axis aberration measurements in primary gaze and downward gaze with binocular fixation. Measurements with the mo...

From the literature the analytical calculation of local power and astigmatism of a wavefront after refraction and propagation is well known; it is, e.g., performed by the Coddington equation for refraction and the classical vertex correction formula for propagation. Recently the authors succeeded in extending the Coddington equation to higher order aberrations (HOA). However, equivalent analyti...

The third-order aberrations of a diffractive optical element with paraxial zone spacings are derived as a function of aperture stop position. It is shown that by placing the stop in the front focal plane, coma and astigmatism are identically zero, assuming an infinitely distant object. In addition, since the element is diffractive, the Petzval sum is also zero. Modulation transfer function comp...

AIMS A blind, randomised, prospective, bilateral study to investigate the efficacy of riboflavin/ultraviolet A corneal collagen cross-linkage to halt the progression of keratoconus. METHODS 24 patients with early/moderate bilateral keratoconus with recent progression were recruited. One eye was randomly assigned to undergo collagen cross-linkage following epithelial removal with riboflavin 0....

PURPOSE To determine patient satisfaction after Artisan phakic intraocular lens (PIOL) implantation to correct myopia. DESIGN Non-comparative prospective case series. METHODS One hundred twenty eyes of 60 patients who had undergone Artisan PIOL implantation to correct myopia were analyzed. A validated questionnaire that consisted of 66 satisfaction items were self-administered by patients 1...

PURPOSE To evaluate the repeatability of wavefront measurements using the NIDEK OPD-Scan. METHODS A total of 179 eyes from 90 healthy volunteers (57 women and 33 men) with no corneal or lenticular pathology and normal visual acuity were enrolled in this study. Mean patient age was 39 years (range: 17 to 85 years). All patients underwent four consecutive measurements by one examiner with the N...

PURPOSE To report the effect of wavefront-guided photorefractive keratectomy and corneal collagen cross-linking (CXL) on visual problems after Ferrara ring segment placement. MATERIALS AND METHODS A 32-year-old male patient was treated with a Ferrara ring segment for keratoconus. One year later, the ring was removed due to severe glare complaints. After 6 months, wavefront-guided photorefract...

OBJECTIVE To compare the mean root mean square (RMS) of total higher order aberrations (HOAs), coma and spherical aberrations in individuals with myopia, hypermetropia and myopic astigmatism. METHODS This prospective analytical study was conducted at Armed Forces Institute of Ophthalmology, Rawalpindi, Pakistan from Jan 2014 to Dec 2014. Two hundred eyes of 121 patients with age ranging from ...