Publications by authors named "Clara Llorens Quintana"
The agreement between fluorescein breakup time (FBUT) estimates and noninvasive breakup time (NIBUT) estimates automatically acquired using two videokeratoscopes was assessed. Small-cone (E300, Medmont) and large-bowl (K5M, OCULUS) Placido-ring-based videokeratoscopes were utilized for automated NIBUT estimation and fluorescein strip method was used for FBUT estimation. 33 subjects completed the study.
View Article and Find Full Text PDFPurpose: To present a new method for 3-dimensional external limbal demarcation on corneoscleral topography derived from optical coherence tomography (OCT). Limbal shape is investigated and compared to other landmarks.
Methods: Images from the anterior segment were obtained with a ultrawide-field (20 mm) OCT.
This study evaluates the effectiveness of objective techniques in assessing dry eye disease (DED) treatment compared with the subjective assessment commonly used in clinical practice. Thirty subjects were recruited for two visits separated by 28(± 3) days of treatment with artificial tears. A buttery of common subjective assessment methods were accompanied by a set of objective techniques including measurement of noninvasive tear film break-up time (NIBUT), lipid layer thickness (LLT), and quantitative evaluation of tear film surface quality and dynamics (TFD).
View Article and Find Full Text PDFPurpose: To measure net corneal astigmatism using optical coherence tomography (OCT) (Avanti) in individuals with keratoconus and compare the repeatability and accuracy with those obtained using Scheimpflug imaging (Pentacam HR).
Setting: Casey Eye Institute, Portland, Oregon.
Design: Prospective cross-sectional observational study.
Purpose: To assess the repeatability and accuracy of corneal astigmatism measurement with a spectral-domain optical coherence tomography (OCT) system (Avanti, Optovue) and compare them with Scheimpflug imaging (Pentacam HR, Oculus) and swept-source optical biometry (IOLMaster 700, Carl Zeiss Meditec AG).
Setting: Casey Eye Institute, Oregon Health & Science University, Portland, Oregon.
Design: Prospective cross-sectional observational study.
Significance: While evaluating the tear-film breakup time, a careful set of precise instructions should be given to the subjects regarding the blink type because it substantially impacts the assessment of tear-film surface quality.
Purpose: The purpose of this study was to determine to what extent the type of blink affects the tear-film breakup time and its assessment using two types of videokeratoscopes and the fluorescein test.
Methods: Thirty-three volunteers were assessed considering two different types of blinks: natural (short) and forced (unnaturally prolonged).
Purpose: To assess the impact of daily disposable soft contact lenses on meibomian gland morphology over a period of 12 months.
Methods: Forty-one subjects (33 experienced and 8 neophytes) were fitted with either silicone-hydrogel or hydrogel daily contact lenses. The study protocol included four visits: baseline, day-2 for contact lens fit and follow-up measurements, as well as after 6 and 12 months of lens wear.
Purpose: To objectively and quantitatively characterize meibomian gland morphology and to investigate the influence of morphological variations on gland function and ocular surface and tear film parameters.
Methods: One hundred fifty subjects were enrolled. The examinations included tear osmolarity, tear meniscus height, bulbar conjunctival hyperemia, noninvasive tear film breakup time, lid margin thickness, foam secretion, meibomian gland expressibility, count of functioning glands, corneal and conjunctival staining, fluorescein breakup time, lid wiper epitheliopathy, and Schirmer test.
Purpose: We present and validate a new methodology for analyzing, in an automated and objective fashion, infrared images of the meibomian glands (MG).
Methods: The developed algorithm consists of three main steps: selection of the region of interest, detection of MG, and analysis of MG morphometric parameters and dropout area (DOA). Additionally, a new approach to quantify the irregularity of MG is introduced.
Unified approach to tear film surface analysis with high-speed videokeratoscopy.
J Opt Soc Am A Opt Image Sci Vis
April 2019
Placido disk videokeratoscopy, when used in a dynamic acquisition mode, can be utilized for noninvasive assessment of tear film quality. The different commercially available videokeratoscopes that incorporate an automatic option to evaluate tear film do not provide consistent measurements due to differences in their designs as well as differences in the algorithms used to analyze the images. Here, a standardized algorithm that can be applied to different instruments is developed.
View Article and Find Full Text PDFPurpose: To assess the relationship between the meibomian gland loss (MGL) and relevant ocular surface clinical parameters as well as the influence of age in this relationship.
Methods: A total of 161 participants (mean age; 42±17 years) were enrolled in this study. Infrared meibography was performed using Keratograph 5M (K5M; Oculus GmbH, Wetzlar).
Significance: Noninvasive high-speed videokeratoscopy equipped with specific software has shown potential for assessing the homeostasis of tear film, providing clinicians with a fast and consistent tool for supporting dry eye diagnosis and management.
Purpose: The purpose of this study was to evaluate the efficacy of a recently proposed method for characterizing tear film dynamics using noninvasive high-speed videokeratoscopy in assessing the loss of homeostasis of tear film.
Methods: Thirty subjects from a retrospective study, of which 11 were classified as dry eye and 19 as healthy, were included.
Purpose: The aim of the current study is to assess, using new technologies, the interaction of four monthly silicone hydrogel contact lenses on the ocular surface and the comfort over 15 days of use.
Methods: Prospective cross-over, randomized and double-masked study including four materials (lotrafilcon-B, samfilcon-A , comfilcon-A and filcom-V3). Clinical examination was performed in the following order: tear meniscus height, first break-up of the tear film, the average time of all tear film breakup incidents, bulbar redness, limbal redness (Keratograph 5M ,Oculus, Germany); central corneal thickness (Pentacam, Oculus, Germany), thermography values (FLIR A325; FLIR Systems Inc.
Purpose: To characterize the mean topographical shape of the human sclera of a normal eye.
Methods: Forty-five participants aged from 19 to 45 years and with no previous ocular surgeries were included in this study. Four three-dimensional (3D) corneo-scleral maps from both eyes were acquired using a corneo-scleral topographer (Eye Surface Profiler).
Significance: The proposed automated approach for estimating the quality of the tear film closes the gap between the manual and automated assessment, translating the high-speed videokeratoscopy technology from scientific laboratories to a clinical practice.
Purpose: To develop and test a new method for characterizing Tear Film Surface Quality with high-speed videokeratoscopy utilizing a fractal dimension approach.
Methods: The regularity of the reflected pattern in high-speed videokeratoscopy (E300; Medmont) depends on tear film stability.
Non-invasive pre-lens tear film assessment with high-speed videokeratoscopy.
Cont Lens Anterior Eye
February 2018
Purpose: To evaluate the effect of two types of daily contact lenses (delefilcon A and omafilcon A) on the tear film and establish whether it is dependent on pre-corneal tear film characteristics using a new method to analyse high-speed videokeratoscopy recordings, as well as to determine the sensitivity of the method in differentiating between contact lens materials on eye.
Methods: High-speed videokeratoscopy recordings were analysed using a custom made automated algorithm based on a fractal dimension approach that provides a set of parameters directly related to tear film stability. Fifty-four subjects participated in the study.
Purpose: To characterize the mean topographic shape of the limbus of a normal human eye and determine whether it depends on age or refractive power.
Setting: University of Manchester, Manchester, United Kingdom.
Design: Prospective case series.