Predicted Visual Impact of a Small Aperture Intraocular Lens in Reducing Higher Order Aberrations in Post-Radial Keratotomy Patients.

The purpose of this study is to evaluate the potential impact of small aperture optics on corneal aberrations in post-RK patients. Preoperative data was evaluated from 32 eyes of 23 post-RK patients. Scheimpflug tomography was used to obtain measurements of corneal HOAs at 6-mm, 4-mm, and 2-mm corneal plane aperture diameters.

Prediction of the small aperture intraocular lens on visual acuity in patients with keratoconus.

Purpose: To investigate the impact of corneal higher-order aberrations (HOAs) on predicted corrected distance visual acuity (CDVA) in patients with keratoconus at varying simulated pupil apertures.

Setting: Ophthalmology Clinics, Medical University of South Carolina, Charleston, South Carolina.

Design: Retrospective chart review study.

12. Endothelial pump and barrier function.

The mammalian cornea maintains its thickness and transparency primarily by the activity of a fluid pump located in the endothelial cell layer. The accepted concept, the "pump-leak" theory, holds that the active transport of solute from the stroma to the aqueous humor leads to a steady state osmotic pressure gradient across the endothelium that balances the imbibition pressure created by the hydrophilic proteoglycans in the stromal ground substance. The details of this process are controversial and some of the classical in vitro studies aimed to explore the fluid pump using low temperature to challenge the regulatory behavior cannot be duplicated in vivo.

Long-term Chronological Changes in Very Asymmetric Keratoconus.

Purpose: To investigate chronological changes in patients with very asymmetric keratoconus (KC) by Scheimpflug-based corneal tomographic evaluation.

Methods: We retrospectively reviewed the clinical records of 382 patients with KC attending a university hospital. Patients who were diagnosed with KC in one eye and forme fruste keratoconus in the other eye at the last visit and followed up with Scheimpflug-based tomographic corneal imaging were included.

Fourier Analysis of Corneal Irregular Astigmatism Due to the Anterior Corneal Surface in Dry Eye.

Objectives: To evaluate corneal irregular astigmatism due to the anterior corneal surface using Fourier harmonic analysis with a Placido ring-based corneal topographer (Placido-based topographer) and three-dimensional anterior segment optical coherence tomography (OCT) in dry eyes.

Methods: Forty-four eyes of 44 subjects with dry eye and 20 eyes of 20 normal control subjects were enrolled. Corneal topographic data were obtained using a Placido-based topographer and OCT.

Screening Patients With Cataract for Premium IOL Candidacy Using Microperimetry.

Purpose: To explore the use of microperimetry in the evaluation of macular dysfunction in patients with cataract, to aid in proper intraocular lens selection (multifocal vs monofocal), and to set expectations for postoperative visual function.

Methods: One randomly chosen eye of 10 patients diagnosed as having mild (1+) to moderate (3+) cataract was evaluated before and 1 week after cataract surgery with the MAIA microperimeter (Centervue S.p.

Comparison of objective and subjective refractive surgery screening parameters between regular and high-resolution Scheimpflug imaging devices.

Purpose: To compare objective and subjective metrics from regular and high-resolution Scheimpflug devices (Pentacam) to determine their equivalence and interchangeability for refractive surgery screening.

Setting: Emory Vision at Emory University, Atlanta, Georgia, USA.

Design: Retrospective comparative case series.

Variability of subjective classifications of corneal topography maps from LASIK candidates.

Purpose: To evaluate the variability of subjective corneal topography map classification between different experienced examiners and the impact of changing from an absolute to a normative scale on the classifications.

Methods: Preoperative axial curvature maps using Scheimpflug imaging obtained with the Pentacam HR (Oculus Optikgeräte, Wetzlar, Germany) and clinical parameters were sent to 11 corneal topography specialists for subjective classification according to the Ectasia Risk Scoring System. The study population included two groups: 11 eyes that developed ectasia after LASIK and 14 eyes that had successful and stable LASIK outcomes.

Absolute color scale for improved diagnostics with wavefront error mapping.

Purpose: Wavefront data are expressed in micrometers and referenced to the pupil plane, but current methods to map wavefront error lack standardization. Many use normalized or floating scales that may confuse the user by generating ambiguous, noisy, or varying information. An absolute scale that combines consistent clinical information with statistical relevance is needed for wavefront error mapping.

Functional optical zone of the cornea.

Purpose: When keratorefractive surgery is used to treat a central corneal diameter smaller than the resting pupil, visual symptoms of polyopia, ghosting, blur, haloes, and glare can be experienced. Progress has been made to enlarge the area of surgical treatment to extend beyond the photopic pupil; however, geometric limitations can pose restrictions to extend the treatment beyond the mesopic pupil diameter and can lead to impediments in night vision. The size of the treated area that has achieved good optical performance has been defined as the functional optical zone (FOZ).

Goodness-of-prediction of Zernike polynomial fitting to corneal surfaces.

Purpose: To determine the goodness-of-prediction of the fitting routine by measuring the difference between topographic corneal surfaces and their Zernike reconstructions as a function of polynomial order and optical zone size for various corneal conditions.

Setting: Corneal research laboratory in a university eye center.

Methods: Corneal topography maps (N = 253) were obtained from the Louisiana State University Eye Center.

Screening patients with the corneal navigator.

Purpose: To present a corneal topography screening device for the detection of corneal ectasias and various refractive procedures based on corneal topography patterns.

Methods: A database of corneal topography patterns were analyzed and used to "train" a neural network on nine different corneal topography patterns using nineteen corneal topography indices of corneal shape and power.

Results: Sample normal and corneal topographies were recognized correctly.

Advantages and disadvantages of the Zernike expansion for representing wave aberration of the normal and aberrated eye.

Purpose: Zernike expansion has been selected for use in describing wavefront aberrations in the human eye. The advantages and limitations of this approach are assessed for eyes with varying degrees of aberration.

Methods: Corneal topography examinations were taken with the Nidek OPD-Scan topographer/aberrometer.

Evaluation of the tear film stability after laser in situ keratomileusis using the tear film stability analysis system.

Purpose: To evaluate the tear film stability of patients before and after laser in situ keratomileusis (LASIK) using the tear film stability analysis system (TSAS).

Design: Prospective observational case series.

Methods: New videokeratography software for a topographic modeling system (TMS-2N) was developed that can automatically capture consecutive corneal surface images every second for 10 seconds.

Zernike polynomial fitting fails to represent all visually significant corneal aberrations.

Purpose: It is assumed that wavefront error data arising from aberrometry are adequately described by a Zernike polynomial function, although this assumption has not been extensively tested. Inaccuracies in wavefront error may compromise clinical testing and refractive correction procedures. The current retrospective study correlates visual acuity with corneal wavefront error and with the residual surface elevation error after fitting with the Zernike method.

Effect of inhibition of inflammatory mediators on trauma-induced stromal edema.

Purpose: To determine the specific biochemical pathways involved in the initial-phase inflammatory response that causes stromal edema after epithelial debridement of the rabbit cornea.

Methods: Adult New Zealand White rabbit corneas were treated with 2 mM synthetic inhibitor of metalloproteinase (SIMP)-1, 1 mM DFU (a specific cyclooxygenase [COX]-2 inhibitor) in 50/50 dimethyl sulfoxide (DMSO)/Ringer's solution, 300 KIU aprotinin (a serine protease inhibitor), 0.05% or 0.