Evaluation of anterior segment parameters in keratoconic eyes measured with the Pentacam system
ABSTRACT To evaluate the alteration in anterior chamber parameters with the progression of keratoconus using a rotating Scheimpflug camera.
Inonu University, Turgut Ozal Medical Center, Ophthalmology Department, Malatya, Turkey.
Two hundred sixteen eyes of 123 patients diagnosed with keratoconus and 224 eyes of 112 normal subjects were evaluated with a Pentacam Scheimpflug camera (Oculus Inc.). Keratoconic eyes were divided into 3 groups according to mean keratometer (K) readings: mild (K = less than 47.0 diopters [D]), moderate (K = 47.0 to 52.0 D), and severe (K = 52.0 D or higher). The following parameters were obtained: thinnest corneal thickness (TCT), anterior chamber depth (ACD), corneal volume (CV), anterior chamber angle (ACA), and anterior chamber volume (ACV).
One hundred twenty-nine eyes had mild keratoconus, 59 had moderate keratoconus, and 35 had severe keratoconus. There were no statistically significant differences between the keratoconus group and control group in age, sex, or eye distribution (P>.05). With the progression of the disease, TCT and ACD were statistically different between all groups (P<.05). There were statistically significant differences in ACA and CV measurements between the mild keratoconus and severe keratoconus groups (P<.05). Also, CV readings were significantly different between the control group and all keratoconus groups (P<.05), although there was no significant difference in ACA measurements (P>.05). Despite a progressive increase in the ACV with disease progression, the differences between groups were not statistically significant (P>.05) except between the severe keratoconus group and the control group (P<.05).
Anterior segment parameters of the eye showed significant alterations with the progression of keratoconus.
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ABSTRACT: Measurements of central corneal thickness (CCT) and intra-ocular pressure (IOP) are important for both diagnostic and therapeutic purposes. The aim of this study was to investigate the short-term variation and intra-subject repeatability of CCT and IOP measurements made with the Tono-Pachyme-ter NT530P (Tonopachy™). Fifty one consecutive automatic measurements of CCT and IOP were tak-en for the right eyes of 15 subjects (11 females and 4 males) aged 20 to 57 years (mean = 32.3 ± 13.5 years). The measured values (CCT and IOP) were compared against each other to establish the intra-subject repeatability and bias of each individual measurement with respect to the means, standard deviations and variances. Three different statistical tests of normality: Kolmogorov-Smirnov (K-S), Lilliefors and Shapiro-Wilks (SW) tests suggested that most of the data was normally distributed, with a few exceptions. The inter-subject or overall mean values and standard deviations for the CCT and IOP samples were 528.2 ± 27.4 μm and 14.4 ± 4.3 mmHg respectively. Although possible outli-ers increased the variability of the measurements of both parameters (CCT and IOP), the data generally showed good repeatability. The results of this study suggest that over short periods of time, the Tonopachy™ gives precise and repeatable measures of CCT and IOP. (S Afr Optom 2012 71(1) 12-21)
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ABSTRACT: To assess the correlation between keratoconus severity and intereye asymmetry of pachymetric data and posterior elevation values and to evaluate their combined accuracy in discriminating normal corneas from those with keratoconus.PLoS ONE 10/2014; 9(10):e108882. DOI:10.1371/journal.pone.0108882 · 3.53 Impact Factor
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ABSTRACT: To evaluate the effect of the keratoconus (KC) cone location on the change in refractive outcomes, corneal aberrations and biomechanics after combined topography-guided photorefractive keratectomy (PRK) and collagen crosslinking (CXL). Prospective, comparative case series METHODS: Topography guided PRK was performed followed by accelerated CXL using riboflavin A and enhanced intensity (30mW/cm(2)) ultraviolet light. Outcome parameters including uncorrected distance visual acuity (UDVA) and best corrected distance visual acuity (BDVA), corneal tomography and biomechanics (corneal hysteresis [CH] and corneal resistance factor [CRF]), and corneal wavefront aberrations were assessed before and a year after the procedure. Eyes were subdivided into two groups preoperatively: group 1 - cone located within the central 2 mm zone and group 2 - cone located outside the central 2 mm zone for statistical analysis. UDVA, BDVA, sphere, cylinder and simulated keratometry improved after treatment in both groups (p<0.05). However, BDVA improved more in group 1 than in 2 (p=0.04) and the other variables were not affected by cone location. A few corneal wavefront Zernike aberrations changed after treatment (p<0.05) but none were affected by cone location (p>0.05). CH and CRF increased after treatment in both groups (p>0.05). Interestingly, the increases in CH and CRF were greater in group 2 than in 1 (p>0.05). Cone location appeared to impact only visual acuity and biomechanics after the combined procedure. The greater increase in CH and CRF in group 2 may indicate differences in the ablation profile and variability in CXL outcomes and requires further study. Copyright © 2014 Elsevier Inc. All rights reserved.American Journal of Ophthalmology 11/2014; 159(3). DOI:10.1016/j.ajo.2014.11.020 · 4.02 Impact Factor