Ethnic differences in higher-order aberrations: Spherical aberration in the South East Asian Chinese eye.

Purpose: To determine the distribution of higher-order corneal and ocular aberrations in a healthy refractive surgery population.

Setting: Island Hospital, Penang, Malaysia.

Methods: In this prospective observational study, 1 eye of ethnic Chinese refractive surgery patients was evaluated with an Orbscan II corneal topographer and a Zywave Hartmann-Shack aberrometer with a 6.

A comparative analysis of intraocular lens power calculation methods after myopic excimer laser surgery.

Purpose: To compare the accuracy and predictability of different intraocular lens (IOL) power calculation methods in eyes after myopic excimer laser surgery.

Methods: Phacoemulsification and IOL implantation outcomes in 37 eyes of 37 patients with prior LASIK or photorefractive keratectomy were documented (amount of correction=-6.92+/-3.

Meridional analysis for calculating the expected spherocylindrical refraction in eyes with toric intraocular lenses.

Purpose: To present a method of calculating the expected spherocylindrical refraction after toric intraocular lens (IOL) implantation and to compare it with the actual outcomes in a small group of patients.

Setting: Eye Institute, Tan Tock Seng Hospital, Singapore.

Methods: The expected refractions of the 2 principal meridians of the cornea (maximum keratometry and minimum keratometry) were calculated separately using the Holladay 1 formula with a modification to the data used for the effective lens position.

Validity of the keratometric index: large population-based study.

Purpose: To determine the accuracy of the keratometric index of 1.3315 based on the Gullstrand model eye in predicting the power of the posterior cornea, Gullstrand's model was compared to a calculated keratometric index derived from actual measurements of the cornea.

Setting: Eye Institute, Tan Tock Seng Hospital, Singapore.

Relationship between the corneal surface and the anterior segment of the cornea: An Asian perspective.

Purpose: To determine the values for the anterior best-fit sphere (BFS) and posterior BFS in an Asian population using the Orbscan II (Bausch & Lomb) slit-scanning Placido disk corneal topographer.

Setting: Hospital-based refractive surgery center.

Methods: This prospective nonrandomized study comprised of 1 eye of 724 subjects.

Corneal elevation indices in normal and keratoconic eyes.

Purpose: To determine an index that distinguishes keratoconus and keratoconus-suspect eyes from normal eyes with Orbscan (Bausch & Lomb) corneal elevation maps.

Setting: Department of Ophthalmology, Tan Tock Seng Hospital, Singapore, and iLaser Centre, Island Hospital, Penang, Malaysia.

Methods: In this initial phase of this multicenter nonrandomized retrospective study, 1 eye of 166 normal subjects, 15 keratoconus patients, and 11 keratoconus suspects was examined at 1 clinic.

NeuroVision treatment for low myopia following LASIK regression.

Purpose: To evaluate a novel non-surgical method for improving vision in a refractive surgery patient.

Methods: A 45-year-old man who had undergone LASIK 5 years previously presented with blurred distance vision. Unaided vision in the right eye was 20/329-2) and 20/20 in the left eye.

Orbscan global pachymetry: analysis of repeated measures.

Purpose: The Orbscan II is a hybrid slit-scanning and Placido disc corneal topographer capable mapping global pachymetry over a 10-mm corneal diameter. In this study, the repeatability of the Orbscan global pachymetry was determined.

Methods: Five consecutive Orbscan examinations were performed on one eye of 20 healthy volunteers by one examiner in one session.

Post-LASIK myopic shift after a trek in the North Pole.

Bilateral laser in situ keratomileusis was performed in a 37-year-old male ethnic Chinese adventurer. Eight weeks postoperatively, the patient made an unassisted trek to the geographic North Pole. After 2 weeks in this environment, a myopic shift of more than -1.

Effect of higher-order wavefront aberrations on binocular summation.

Purpose: To determine the effect of individual Zernike wavefront aberrations on binocular summation and binocular visual acuity.

Methods: A 0.25-microm wavefront aberration of second, third and fourth order Zernike modes were introduced into a set of log minimum angle of resolution unit (logMAR) visual acuity charts convolved by CTView.