Central Corneal Thickness Values Research Articles

Laser peripheral iridotomy changes anterior chamber architecture.

The pressure gradient between anterior and posterior chamber in acute angle closure (AAC) and primary angle closure suspects is balanced by a sufficient laser peripheral iridotomy (LPI). The anterior chamber changes induced by LPI in patients with unilateral AAC were examined and compared to healthy eyes to define threshold values, which may help to discriminate between healthy and diseased eyes. Using Scheimpflug photography, anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and central corneal thickness (CCT) were measured before and after LPI in both eyes of unilateral AAC cases. These measurements were compared to a group of healthy control eyes to determine threshold values for ACD, ACV, and ACA. The ACD, ACV, and ACA increased significantly in the 25 AAC eyes after LPI. The ACD, ACV, ACA, and CCT values in the AAC eyes obtained before LPI were compared to a control group of 59 healthy eyes with wide open chamber angles. The cutoff values revealed by receiver operating characteristic analysis were 2.1 mm for ACD, 90.5 mm2 for ACV, and 27.25° for ACA. Our results confirm the significant changes of the anterior segments architecture induced by LPI in AAC eyes. The found threshold values for ACD, ACV, and ACA may help in daily clinical routine to discriminate between healthy eyes and those in need for a prophylactic LPI.

Central corneal thickness and corneal curvature in patients with rheumatoid arthritis.

The aims of this study were to determine the central corneal thickness (CCT) and corneal curvature (CC) in patients with rheumatoid arthritis (RA), and to evaluate the correlations between the CCT, CC, RA activity, and RA duration. Fifty-four RA patients (104 eyes; 35 with dry eye, 69 without dry eye) and 21 age- and gender-matched control patients (42 eyes) were enrolled in the study. The CCT and CC were measured by ultrasonic pachymeter and autorefractor-keratometer, respectively. RA activity was assessed using the disease activity score (DAS) 28. The independent samples' t test and Pearson correlation analysis were used in the statistical analyses. Mean CCTs were found to be 535.88±38.24, 530.46±32.88, 538.64±40.64, and 543.40±40.66μm in all RA eyes, RA with dry eyes, RA without dry eyes, and control eyes, respectively. Mean keratometry (K) readings were found to be 43.84±1.76, 43.73±1.23, 43.90±1.98, and 43.60±1.48D in all RA eyes, RA with dry eyes, RA without dry eyes, and control eyes, respectively. There were no significant differences in CCT values (p values, 0.293, 0.134, and 0.550, respectively) and K readings (p values, 0.435, 0.681, and 0.402, respectively) between the RA and control eyes. These findings led us to the conclusion that the CCT and K readings were not significantly associated with DAS (p values, 0.678 and 0.812, respectively) and RA duration (p values, 0.108 and 0.080, respectively). Our results show that CCTs and CCs were not significantly different between the RA eyes and control eyes. CCTs and CCs were also not associated with RA activity and RA duration.

Determination of normal values of intraocular pressure and central corneal thickness in healthy premature infants—a prospective longitudinal study

To evaluate the longitudinal change of intraocular pressure (IOP) and central corneal thickness (CCT) in healthy premature infants. Premature infants born at 28weeks' gestational age were included in this prospective, single-center longitudinal study. IOP was measured by handheld applanation tonometer (Tono-Pen Avia); CCT measurements were performed by ultrasonic pachymeter. Examinations were held at 32weeks' gestational age initially and at 2-week intervals thereafter for a total of 5 consecutive measurements by the same ophthalmologist. A total of 110 right eyes of 110 healthy premature infants were analyzed. The mean IOP at 32weeks' gestational age was 18.28±2.78mm Hg; mean CCT, 670.56±55.72μm. Mean IOP and CCT thereafter were 16.13±2.20mm Hg and 613.67±48.11μm in week 34, 14.67±2.04mm Hg and 579.24±43.73μm in week 36, 13.49±2.08mm Hg and 551.91±40.75μm in week 38, and 13.21±1.94mm Hg and 546.18±38.70μm in week 40. The longitudinal changes of mean IOP and CCT values between 5 consecutive measurements were statistically significant (P<0.001, for each). IOP and CCT values decrease longitudinally in healthy premature infants between 32 and 40weeks' gestational age. Elevated IOP values, which were identified in the early premature period, seem to be associated with higher CCT values.

Ectasia risk factors in refractive surgery

This review outlines risk factors of post-laser in situ keratomileusis (LASIK) ectasia that can be detected preoperatively and presents a new metric to be considered in the detection of ectasia risk. Relevant factors in refractive surgery screening include the analysis of intrinsic biomechanical properties (information obtained from corneal topography/tomography and patient’s age), as well as the analysis of alterable biomechanical properties (information obtained from the amount of tissue altered by surgery and the remaining load-bearing tissue). Corneal topography patterns of placido disk seem to play a pivotal role as a surrogate of corneal strength, and abnormal corneal topography remains to be the most important identifiable risk factor for ectasia. Information derived from tomography, such as pachymetric and epithelial maps as well as computational strategies, to help in the detection of keratoconus is additional and relevant. High percentage of tissue altered (PTA) is the most robust risk factor for ectasia after LASIK in patients with normal preoperative corneal topography. Compared to specific residual stromal bed (RSB) or central corneal thickness values, percentage of tissue altered likely provides a more individualized measure of biomechanical alteration because it considers the relationship between thickness, tissue altered through ablation and flap creation, and ultimate RSB thickness. Other recognized risk factors include low RSB, thin cornea, and high myopia. Age is also a very important risk factor and still remains as one of the most overlooked ones. A comprehensive screening approach with the Ectasia Risk Score System, which evaluates multiple risk factors simultaneously, is also a helpful tool in the screening strategy.

Accelerated (18 mW/cm(2)) Corneal Cross-Linking for Progressive Keratoconus: 18-Month Results.

The aim of this study is to report the results of 18 months of follow-up after treatment with accelerated (18 mW/cm(2)) corneal cross-linking in patients with progressive keratoconus. Forty-two eyes of 42 patients with progressive keratoconus were included in this retrospective study. All patients underwent accelerated corneal cross-linking at an irradiance of 18 mW/cm(2) for 5 min (total surface dose 5.4 J/cm(2)). Visual acuity, topographic findings (Kflat, Ksteep, Kaverage, and apical keratometry), and central corneal thickness were evaluated during the 18-month follow-up period. The mean ± standard deviation age of the 16 female and 26 male patients was 24.28 ± 6.32 years (range 14-36). Uncorrected distance visual acuity improved clinically significant from 0.52 ± 0.31 to 0.44 ± 0.25 logMAR (P = 0.031), and corrected distance visual acuity improved clinically significant from 0.34 ± 0.21 to 0.28 ± 0.19 logMAR (P = 0.018). At the last examination during the follow-up period, the flat keratometry (Kflat) decreased from a baseline of 45.65 ± 2.71 to 45.41 ± 2.72 diopters (D) (P = 0.001), the steep keratometry (Ksteep) decreased from 49.20 ± 3.54 to 48.96 ± 3.43 D (P = 0.023), and apical keratometry decreased from 56.62 ± 6.43 to 55.19 ± 5.69 D (P = 0.001), all of them were clinically significant at the 18-month visit. The preoperative values of central corneal thickness changed from 458.95 ± 38.79 to 461.85 ± 41.36 μm 18 months after the operation (P = 0.476). The accelerated corneal cross-linking was found to be effective for the stabilization of progressive keratoconus during the 18 months of follow-up visits.

Corneal biomechanics in asymmetrical normal-tension glaucoma.

PurposeWe aimed to assess corneal biomechanics using the ocular response analyzer in patients with normal-tension glaucoma (NTG), and to evaluate the relationship between corneal biomechanics and visual field loss.MethodsThis was a prospective observational case series including patients with bilateral asymmetric NTG. For all patients, corneal hysteresis (CH), corneal resistance factor (CRF), CH − CRF difference, and central corneal thickness values were matched against the mean deviation (MD) of the visual field and the cup/disc ratio. For paired-eye comparison in each patient, both eyes were categorized into a better-eyes group and a worse-eyes group according to lower and higher corneal-compensated intraocular pressure readings, respectively. Statistical analysis was carried out with the independent-samples Student’s t-test, and the level of statistical significance was set at 0.05. Correlation was assessed using Pearson’s correlation coefficient.ResultsThe study included 240 eyes of 120 patients. CH was inversely proportional to the MD in the visual field (P=0.01). CRF in both eyes was inversely proportional to the MD of the visual field (P=0.01). CH − CRF difference was directly proportional to the MD of the visual field (P=0.01). For paired-eye comparison, lower corneal-compensated intraocular pressure was associated with higher CH, higher CRF, smaller cup/disc ratio, and less deterioration of MD of visual field.ConclusionCH, CRF, and CH − CRF are more powerful predictors of NTG progression than central corneal thickness.

Effect of 2% fluorescein on Scheimpflug central corneal thickness measurements.

To assess central corneal thickness (CCT) changes measured with Scheimpflug device following instillation of 2% fluorescein in normal subjects. This was a prospective randomized study of 60 hospital volunteers. After baseline CCT measurements of both eyes of 40 subjects were obtained using Scheimpflug system, a drop of preservative-free 2% fluorescein, was instilled in one eye and in other eye, one drop of normal saline (control). Measurements were repeated after 1, 2, 5, 10, 20, 30, 40, 50 and 60min (continuous assessment group). Twenty subjects had baseline CCT taken, then fluorescein was instilled in one eye and measurements were taken at 1min. Ten eyes had saline rinse after 1min and 10 other eyes did not, measurements were repeated at 2min (eye rinse group). The mean baseline CCT for continuous assessment group was 546.2 ±32.1 µm (range, 489.0-606.0), control eyes was 546.6±30.7 µm (range, 489.0-602.0). At 1min after fluorescein instillation, CCT significantly increased by 37.0±34.0 µm (P<0.001), then decreased gradually, reaching baseline at 60min. CCT variations were not significant in control group (P>0.05). For eye rinse group, CCT mean differences between baseline and 2min were 18.2 µm (95 % CI: -54.7 to 18.3) with rinse and 26.5 µm (95% CI: -62.9 to 9.9) without rinse; paired sample tests were not significant (P>0.05). The presence of fluorescein increased CCT value to a clinically relevant level of 6.8%. Eye rinse did not significantly reduce the effect at 2min post fluorescein timepoint.

Intraoperative OCT Pachymetry in Patients Undergoing Dextran-Free Riboflavin UVA Accelerated Corneal Collagen Crosslinking

ABSTRACTPurpose: To assess intraoperative corneal pachymetry in patients undergoing accelerated corneal collagen crosslinking with a dextran-free riboflavin solution.Methods: Prospective, non-comparative, multicenter interventional study. Thirty patients with progressive keratoconus were enrolled in the study from the Siena Crosslinking Center™ in Siena, Italy and the Eye Center in Catanzaro, Italy. The mean age was 26.9 ± 6.5 years. Patients underwent pulsed light accelerated crosslinking (PL-ACXL) by KXL I UV-A source (Avedro Inc., Waltham, MS, USA) with 8 min (1 s on/1 s off) of UV-A exposure, 30 mW/cm2 and an energy dose of 7.2 J/cm2. Corneal stroma was soaked with a dextran-free 0.1% riboflavin solution plus hydroxyl-propyl methylcellulose (HPMC) (VibeX Rapid, Avedro). Intraoperative corneal thickness was preoperatively (PRE-OP) evaluated by corneal optical coherence tomography (iVUE Optovue Inc., Fremont, CA, USA) after epithelium removal (EPI-R), after 10 min of riboflavin soaking (RS) and after UV-A irradiation (IR). Statistical analysis was conducted using a Wilcoxon test and SPSS v16.0. A p-value of <0.05 was considered to be statistically significant.Results: Average PRE-OP central corneal thickness (CCT) and thinnest corneal thickness (TCT) were 437.3 ± 36.9 and 418.9 ± 28.8 μm, respectively. Average EPI-R CCT and TCT values were 388.5 ± 36.8 and 381.5 ± 36.61 μm, respectively. Average CCT and TCT values after 10 min RS were 385.2 ± 37.8 and 380.6 ± 36.7 μm, respectively. The final average CCT and TCT values after IR were 379.4 ± 37.2 and 378.1 ± 36.4 μm, respectively.Conclusions: The study demonstrated a non-statistically significant intraoperative corneal thickness reduction in patients undergoing PL-ACXL corneal collagen crosslinking by using dextran free HPMC 0.1% riboflavin solution.

Ocular surface findings in patients with rheumatoid arthritis under methotrexate or biological agent therapy

Purpose: To evaluate the ocular findings in patients with rheumatoid arthritis (RA) treated with disease-modifying antirheumatic drugs (DMARDs) such as methotrexate (MTX) or MTX with biological agents.Methods: One hundred and twelve eyes of 56 patients with RA and treated with MTX or MTX with biological agents were included in the study. Patients were divided into two groups using DMARDs only (group 1) and patients using DMARDs and biologic agents together (group 2). In both groups; Schirmer’s II test, tear film break-up time (tBUT), central corneal thickness (CCT), corneal volume (CV), intraocular pressure (IOP) measurement, and anterior segment and fundus examinations of the eye with slit lamp were carried out. Ocular surface disease index (OSDI) score questionnaire were performed.Results: Thirty-eight patients with a mean age of 53.00 ± 8.19 years were in group 1 and 18 patients with a mean age of 51.00 ± 9.54 years were in group 2. The mean duration of RA was 6.89 ± 7.96 years in group 1 and 5.70 ± 9.00 years in group 2. There was a statistically significant difference between two groups with tBUT, CCT, CV, IOP (p < 0.05) and there was no significant difference with age, sex, disease duration, disease activity, and Schirmer’s II test (p > 0.05). The disease duration showed a significant moderate negative correlation with CCT and CV in group 2 (p < 0.05).Conclusions: Although tBUT values were significantly higher in the combination treatment group, CCT and CV values were significantly lower. Due to the decrease in corneal thickness, IOP was determined to be significantly lower.

Comparison of intraocular pressure measurements with different contact tonometers in young healthy persons

To analyze the correlation of Goldmann applanation tonometer (GAT), I-Care tonometer and Tono-Pen tonometer results in young healthy persons, and to investigate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements recorded with these tonometers. We conducted a pilot clinical study in 78 eyes of 78 subjects aged 22-28 years old (44 women and 34 men; mean age 23.8±1.19y). IOP was measured using GAT, I-Care and Tono-Pen tonometers, followed by measurements of CCT. Statistical analysis was performed using SPSS 20.0. The mean IOPs and standard deviation (±SD) for GAT, I-Care and Tono-Pen were 15.62±2.281 mm Hg, 16.29±2.726 mm Hg and 16.32±2.393 mm Hg, respectively. The mean CCT was 555.15±29.648 µm. Clear positive correlations between GAT and I-Care, GAT and Tono-Pen, and I-Care and Tono-Pen tonometers were found (r=0.867, P<0.001; r=0.861, P<0.001; r=0.915, P<0.001, respectively). In comparison between devices, Bland-Altman analysis showed a significant mean difference (MD) in the measurements by GAT and I-Care of -0.679 mm Hg and by GAT and Tono-Pen of -0.705 mm Hg ( P<0.001), but there was no significant difference between I-Care and Tono-Pen ( P>0.05). Both non-gold standard tonometers were affected by CCT; that is, both I-Care and Tono-Pen tonometer values were significantly higher with higher CCT means (>555 µm; MD=-1.282, P<0.001; MD=-0.949, P<0.001, respectively) compared with GAT. Both I-Care and Tono-Pen tonometers overestimated IOP compared with the GAT values. Either the I-Care or Tono-Pen tonometer could be used instead of GAT because there was no significant difference between their results. Higher CCT values (>555 µm) were associated with overestimated IOP values.

Comment on: Intraocular pressure and anetrior segment anatomy after phacoemulsification surgery

Sir, We read the article, “The effect of phacoemulsification surgery on intraocular pressure and anterior segment anatomy of the patients with cataract and ocular hypertension.” by Cetinkaya et al. with a great interest.[1] The authors aimed to evaluate the effect of phacoemulsification surgery on intraocular pressure (IOP), anterior chamber depth (ACD), iridocorneal angle (ICA), and central corneal thickness (CCT) of the patients with cataract and ocular hypertension. They concluded that phacoemulsification surgery decreases IOP and increases ACD and ICA in the short-term, but in the long-term, it does not cause any significant changes. We congratulate the authors for their lightening study and would like to make some contributions and criticism about IOP, ICA, and CCT measurement methods and times of the measurements in the study. We know that CCT value is very important for the exact evaluation of many ophthalmologic diseases such as glaucoma, keratoconus, corneal dystrophy, and kerato-refractive surgery.[2,3,4] Ultrasound pachymetry (USP) is the most frequently used clinical technique and the gold standard of measuring CCT. However, placement of the probe on the corneal center is important and the perpendicularity of the probe in relation to the cornea is often difficult to ascertain. This is subjective and may cause operator-dependent errors due to off-center placement.[3] Usually, topical anesthesia is instilled before USP examination, and this could also induce bias. It is reported that topical anesthesia needed for USP may cause the cornea to swell and may give variations in CCT from −10 μm to +30 μm.[4] The results of the iridocorneal angle evaluation using Goldmann 3-mirror lens is also affected by examiner. We think that if measurements were performed by different examiners, this might be affected the results. The authors did not inform if all measurements were performed by the same examiner or not during 2 years study period. In addition, using the mean value of multiple USP measurements in a period for one person could reduce the risk of error. Another important factor which might be affected the results is a diurnal variation of the CCT and IOP. It is reported that there cornea swells during sleep upon eye opening and deswells about 2 h after eye opening. It is known that the mean circadian fluctuations of CCT are about 15 µm, and the circadian fluctuations may affect the IOP up to about 11 mmhg.[5] The authors also did not give any information about the time of the day during measurements. We think that if measurement were performed in different times of the day, this might be affected the results. We congratulate the authors and thanks for their understanding. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Comparison of Goldmann applanation tonometer, Tono-Pen and noncontact tonometer in children.

Background:To evaluate the agreement of Goldmann applanation tonometer (GAT) with Tono-Pen and noncontact tonometer (NCT) for measurement of intraocular pressure (IOP) in pediatric age group and to evaluate the correlation between central corneal thickness (CCT) and IOP measured with the tonometers used.Materials and Methods:IOP was measured in 200 eyes in a group of Indian children, aged between 8 and 18 years using three different tonometers: NCT, the Tono-Pen and GAT. All IOP readings were made in the office settings by the same examiner. Readings obtained were compared between the instruments and with the CCT for each tonometer. Tonometer inter-method agreement was assessed by the Bland–Altmann method. The relations of CCT with absolute IOP values and inter-tonometer differences were analyzed by linear regression.Results:The mean age was 13.37 ΁ 3.51 years. The mean IOP values recorded with NCT; Tono-Pen and GAT were 14.38, 15.63, and 12.44 mmHg, respectively. Both Tono-Pen and NCT recorded statistically higher IOP values than the GAT (P = 0.00) regardless of the CCT. The percentage increase of IOP measured over GAT was 15.66% for NCT and 25.70% for Tono-Pen which was also statistically significant. A correlation was found between CCT and IOP values obtained with all the three tonometers.Conclusion:IOP measurements on children vary significantly between instruments and correlations are affected by the corneal thickness. Further studies on children are needed to determine which instrument is most appropriate and to derive a normative IOP scale for the growing eye.

Dynamic changes in optic disc morphology, choroidal thickness, anterior chamber parameters, and intraocular pressure during Valsalva maneuver.

To investigate the effects of the Valsalva maneuver (VM) on optic disc morphology, choroidal thickness, and anterior chamber parameters. This prospective observational study included 60 eyes of 60 healthy subjects. The anterior chamber parameters, including central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber angle (ACA), anterior chamber volume (ACV), pupil diameter (PD), axial length (AL), subfoveal and peripapillary choroidal thickness, optic disc parameters, and intraocular pressure (IOP), were measured at rest and during VM. VM did not have any significant influence on AL, subfoveal and peripapillary choroidal thickness, optic disc area, rim area, cup area, cup-to-disc area ratio, vertical cup-to-disc ratio, rim volume, cup volume, and nerve head volume measurements (for all; p >0.05). IOP and PD significantly increased during VM (for both; p <0.001). VM significantly decreased CCT, ACD, ACA, and ACV values (for all; p <0.001). Moreover, the optic nerve cup volume decreased and the horizontal cup-to-disc ratio significantly increased during VM (for both; p <0.05). VM may cause transient changes in IOP, optic disc morphology, and anterior chamber parameters.

Differences in Central Corneal Thickness between Spectral Domain-Optical Coherence Tomography and Ultrasound Pachymetry in Patients with Dry Eye Disease.

Purpose. To compare central corneal thickness (CCT) values via Spectral Domain-Optical Coherence Tomography (SD-OCT) and ultrasonic pachymetry in patients with severe dry eye disease (DED) to determine the level of agreement between these 2 methods. Methods. The paired samples t-test was used to compare CCT values in severe DED patients. Matching analysis between methods was performed using intraclass correlation coefficient (ICC). Intrasession reliability of the measurement methods was calculated via the concordance correlation coefficient (CCC), variation equivalent, and Pearson's correlation coefficient. The Bland-Altman procedure was used to graphically represent the differences between CCT values. Results. The study included 56 eyes of 24 female and 4 male patients. Mean age of the patients was 50.9 ± 11.3 years. Mean CCT via Cirrus SD-OCT was 523.82 ± 30.98 μm versus 530.050 ± 31.85 μm via ultrasonic pachymetry (paired samples t-test, P < 0.001). The Bland-Altman plot showed good agreement between the examiners. The ICC for repeatability was 0.974. The CCC between the 2 methods' CCT values was 0.973. The variation equivalent was 0.976 and Pearson's correlation coefficient was 99.3%, which also indicated high correlation between the 2 methods' measurements. Conclusions. The present findings show that in patients with severe DED Cirrus SD-OCT provides reliable intraobserver CCT values.

Association Between Alzheimer's Disease and Glaucoma: A Study Based on Heidelberg Retinal Tomography and Frequency Doubling Technology Perimetry.

Aim: To assess the frequency of glaucoma-like alterations in Alzheimer's disease (AD) patients using Heidelberg Retinal Tomograph III (HRT-3) and Frequency Doubling Technology (FDT) perimetry.Methods: The study included 51 eyes of 51 AD subjects and 67 eyes of 67 age- and sex-matched controls. Subjects underwent an ophthalmological examination including measurements of intraocular pressure (IOP), Matrix FDT visual field testing, optic nerve head morphology and retinal nerve fiber layer thickness (RNFLt) assessment by slit-lamp biomicroscopy and HRT-3.Results: The frequency of alterations was significantly higher in the AD group (27.5 vs. 7.5%; p = 0.003; OR = 4.69). AD patients showed lower IOP (p = 0.000) despite not significantly different values of central corneal thickness (CCT) between the groups (p = 0.336). Of all the stereometric parameters measured by HRT-3, RNFLt was significantly lower in AD patients (p = 0.013). This group also had significantly worse results in terms of Moorfields Regression Analysis (p = 0.027). Matrix showed significantly worse Mean Deviation (MD) (p = 0.000) and Pattern Standard Deviation (PSD) (p = 0.000) values and more altered Glaucoma Hemifield Test (p = 0.006) in AD patients. Pearson's R correlation test showed that Mini Mental State Examination is directly correlated with MD (R = 0.349; p = 0.034) and inversely correlated with PSD (R = −0.357; p = 0.030).Conclusion: Patients with AD have a higher frequency of glaucoma-like alterations, as detected by the use of HRT-3. These alterations were not associated with elevated IOP or abnormal CCT values.

Long-term follow-up results of corneal collagen cross-linking in keratoconus

Objective: To evaluate the changes in corneal parameters (keratometry, corneal thickness, topography indices) after corneal collagen cross-linking in keratoconus. Methods: The medical records of 6 patients who underwent corneal collagen cross-linking treatment for keratoconus and have been followed-up for a minimum of 24 months were recruited. Best corrected visual acuity (BCVA), maximum keratometry (Kmax), central corneal thickness (CCT) values and corneal topography indices: index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), minimum radius of curvature (Rmin), index of height asymmetry (IHA), and index of height decentralisation (IHD) were recorded. Results: The mean preoperative Kmax value was 46.67±4.15 (43.30-57.10) D and the mean Kmax value at the final postoperative visit was 45.41±2.95 (43.00-53.20) D. Mean preoperative CCT was 494.70±33.69 (438-537) µm and final postoperative mean CCT was 495.60±34.99 (433-539) µm. The deterioration in corneal topography indices stopped during the follow-up period of each case. Conclusion: Stopping the deterioration of corneal parameters in keratoconus is the desired outcome after cross-linking treatment. Our results found an improvement or at least stabilization in all topography indices in keratoconus patients. J Clin Exp Invest 2015; 6 (4): 343-350 Key words: Keratoconus, corneal collagen cross-linking, corneal topography

Are There Any Changes in Corneal Biomechanics and Central Corneal Thickness in Fuchs’ Uveitis?

Purpose: To compare corneal biomechanics, intraocular pressure (IOP) and central corneal thickness (CCT) of 38 patients with unilateral Fuchs’ uveitis (FU) with 42 healthy controls.Methods: Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated and corneal-compensated IOP (IOPg and IOPcc, respectively) and CCT were measured.Results: The mean CH, CRF, and IOPg of the involved FU eyes were significantly lower (9.5 ± 1.6, 9.0 ± 1.9 and 13.1 ± 4.3 mmHg) than contralateral eyes (10.1 ± 1.7, 9.9 ± 1.7 and 14.6 ± 3.4 mmHg), and controls (10.5 ± 1.5, 10.3 ± 1.5 and 14.8 ± 2.5 mmHg), respectively. There was no significant difference for mean IOPcc between involved FU or contralateral eyes and controls (14.8 ± 4.1, 15.5 ± 3.4 and 15.0 ± 2.7 mmHg). The CCT values correlated with CH and CRF in the involved and contralateral eyes.Conclusions: Involved FU eyes had lower CH, CRF, and IOPg than contralateral eyes and controls, with no difference regarding IOPcc.

Anterior segment morphologic changes related to α-1 adrenergic receptor antagonists use.

To investigate possible changes in anterior segment parameters with the Pentacam in patients taking tamsulosin or doxazosin for benign prostatic hyperplasia. This prospective, cross-sectional study was conducted at Necip Fazil City Hospital, Kahramanmaras, Turkey. Patients included in the study were grouped as follows: 29 patients treated with tamsulosin (group 1), 27 patients treated with doxazosin (group 2), and 40 untreated controls (group 3). Right eyes of each patient were included in the study. All patients underwent examination with the Pentacam under standard dim light conditions and with undilated pupils. Anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA) width, central corneal thickness (CCT), corneal volume (CV), and pupil diameter (PD) were recorded. Mean duration of treatments was 2.7 ± 1.2 (1-5) and 2.4 ± 0.9 (1-5) years in groups 1 and 2 (p = 0.276). The ACD, ACV, ACA width, and PD were statistically significantly decreased in groups 1 and 2 when compared to group 3 (p&lt;0.05). There were no statistically significant differences among the groups in mean values of CCT and CV. In this study, decreased ACD, ACV, ACA width, and PD values were detected in tamsulosin and doxazosin groups when compared to controls. These findings should be considered during anterior segment examinations and surgeries.

Central corneal thickness and intraocular pressure in premature infants.

To evaluate the central corneal thickness (CCT) and intraocular pressure (IOP) of premature infants and to document correlation of them with gestational age, chronological age, and birth weight of infants. Using a hand-held applanation tonometer and a portable pachymeter, IOP and CCT of 170 premature infants were measured just before initial retinopathy of prematurity screening examination and re-measured 4 weeks after the first visit. The CCT and IOP were positively correlated during the first (r = 0.616, p < 0.001) and second (r = 0.564, p < 0.001) visits. The mean CCT at first and second visits were 568.1 ± 22.1 (527-628) and 561.6 ± 21.4 (520-619) µm, consecutively (p < 0.001). Gestational age, chronological age and birth weight of infants were found to be negatively correlated with CCT at first (r = -0.751, p < 0.001; r = -0.745, p < 0.001; r = -0.581, p < 0.001, consecutively) and second (r = -0.729, p < 0.001; r = -0.729, p < 0.001; r = -0.555, p < 0.001, consecutively) visits. The mean IOP at first and second visits were 14.1 ± 1.9 (11-19) and 13.7 ± 1.7 (11-18) mmHg, consecutively (p < 0.001). Gestational age, chronological age, and birth weight of infants were found to be negatively correlated with IOP at first (r = -0.724, p < 0.001; r = -0.715, p < 0.001; r = -0.558, p < 0.001, consecutively) and second (r = -0.704, p < 0.001; r = -0.703, p < 0.001; r = -0.518, p < 0.001, consecutively) visits. CCT and IOP of the premature infants with a smaller gestational age were found to be higher (p < 0.001 for both). Premature infants with smaller gestational age have higher CCT and IOP values when compared to older infants. These values tend to become lower 4 weeks after the first examination as infants become older. The CCT and IOP were positively correlated with each other and both were negatively correlated with gestational age, chronological age, and birth weight during first and second visits.

Changes in central corneal thickness and refractive error after thin-flap laser in situ keratomileusis in Chinese eyes.

BackgroundRefractive stability is influenced by alterations in corneal curvature and corneal thickness after laser in situ keratomileusis (LASIK). The aim of this study was to analyze the changes of central corneal thickness (CCT) and refractive error following thin-flap LASIK surgery in Chinese eyes.MethodsOne hundred and fifty-eight myopic patients (302 eyes) who underwent thin-flap LASIK surgery were prospectively evaluated. CCT was measured by non-contact specular microscopy before, and 1 day, 1 week, and 1, 3, and 6 months following surgery. Age, refractive error, and optic zone diameter were also recorded.ResultsPreoperatively, the mean CCT was 531.6 ± 24.3 μm. At 1 day, 1 week, and 1, 3, and 6 months after surgery, mean CCTs were 431.4 ± 38.4 μm, 422.6 ± 3 7.8 μm, 427.2 ± 38.0 μm, 434.4 ± 38.2 μm, and 435.6 ± 38.0 μm, respectively. Significant changes were detected in CCT values at each time point after thin-flap LASIK treatment (P < 0.05). The mean preoperative spherical equivalent (SE) was −5.73 ± 2.30 diopters (D). At 1 day, 1 week, and 1, 3, and 6 months after surgery, it was 0.26 ± 0.58 D, 0.54 ± 0.52 D, 0.49 ± 0.53 D, 0.45 ± 0.49 D, and 0.37 ± 0.42 D, respectively. The spherical equivalent refraction at 6 months postsurgery was close to the predicted value (0.34 ± 0.30 D). The changes in CCT within 6 months (4.06 ± 9.99 μm) were negatively correlated with age, preoperative refractive error, and optical zone diameter, respectively (r = −0.180, P < 0.05; r = −0.187, P < 0.001; r = −0.171, P < 0.05, respectively). No significant correlation was found between CCT changes and SE changes at different time points, postoperatively.ConclusionsCCTs decreased significantly at 1 day after surgery, and continued to decline at 1 week after surgery, then increased over time. From postoperative 1 week, SE over time continually shifted to the myopic side.