PURPOSE To investigate thickness profile changes of the corneal epithelium and Bowman's layer at the vertical and horizontal meridians with overnight myopia orthokeratology (OK) lenses. METHODS Twenty subjects (age range: 19-33 years) wore reverse-geometry rigid gas-permeable OK lenses in both eyes for 30 days. Before lens wear and after 1, 7, and 30 days of overnight lens wear, evaluation of...

PURPOSE To evaluate an interferometric method for measuring the thickness of the pre- (PLTF) and postlens tear film (POLTF) in subjects wearing hydrogel contact lenses. The precision and accuracy of measuring postlens tear thickness is compared with a previous method based on optical pachymetry and mechanical measurement of contact lens thickness. METHODS Reflectance spectra (562-1030 nm) fro...

PURPOSE To investigate topographical thickness changes of the epithelium and total cornea measured with optical coherence tomography (OCT) after overnight wear of rigid gas-permeable lenses. METHODS Reverse geometry design CRT (Dk=100) rigid (test) lenses (Paragon Vision Sciences, Mesa, AZ) were randomly fitted on one eye of each of 20 neophyte subjects (mean age, 24.6 +/- 2.7 years) and the ...

BACKGROUND Ocular biometric parameters can be influenced by race, ethnicity, and genetics; their differences across different populations can probably explain differences in refractive errors in these populations. The aim of this study is to determine the normal range of axial length, anterior chamber depth, lens thickness, and vitreous chamber depth in the population of Shahroud in the north o...

PURPOSE To study the 24-hour changes in axial length, lens thickness, and anterior chamber depth in rabbits and to examine the role of ocular sympathetic activity on these changes. METHODS Young adult rabbits were entrained to a daily 12-hour light-12-hour dark cycle. Axial length, lens thickness, and anterior chamber depth were measured using ultrasonic techniques. In the first group of 12 r...

BACKGROUND The aim was to evaluate the turbidity and thickness of the post-lens tear layer and its effect on visual quality in patients with keratoconus after the beginning of lens wear and before lens removal at the end of eight hours. METHODS Twenty-six patients with keratoconus (aged 36.95 ± 8.95 years) participated voluntarily in the study. The sample was divided into two groups: patients...

The mechanics governing the fit of a soft contact lens on the eye are examined through the development of a finite element analysis model. A linearly elastic lens is placed on a rigid eye with a lubricating viscoelastic tear layer. The mechanics of fit are described in terms of the pressure distribution through the tear layer, the contact pressure at the lens/tear interface, the tear film thick...

PURPOSE To evaluate the influence of biometric variables on refractive outcomes after cataract surgery in angle-closure glaucoma (ACG) patients. METHODS In this case-control study, 42 ACG patients, 40 open-angle glaucoma (OAG) patients, and 35 controls without glaucoma who had undergone conventional cataract surgery were enrolled consecutively. Electronic medical records, including preoperati...

PURPOSE To investigate biometrically the differences between plateau iris configuration (PIC) eyes and primary open angle glaucoma with narrow angle eyes. METHODS A comparative study involving a case series with 20 eyes of 11 plateau iris configuration patients and 45 eyes of 27 primary open angle glaucoma with narrow angle eyes patients was done. The following measurements were taken: cornea...

Purpose: To compare central corneal thickness (CCT), corneal endothelial cell density, and lens capsule thickness in normotensive patients with and without pseudoexfoliation syndrome (PXS) Methods: This was a prospective, comparative, descriptive study. Normotensive candidates for cataract surgery with (study group) and without (control group) PXS were enrolled in the study. CCT and corneal end...