Thinnest Corneal Research Articles

Differences of Corneal Biomechanics Among Thin Normal Cornea, Forme-Fruste Keratoconus, and Cornea After SMILE.

Background: To compare the corneal biomechanics of thin normal cornea (TNC) with thinnest corneal thickness (TCT) (≤500 µm), forme-fruste keratoconus (FFKC) and cornea after small incision lenticule extraction (Post-SMILE) had their central corneal thickness (CCT) matched by Corneal Visualization Scheimpflug Technology (Corvis ST). Methods: CCT were matched in 23 eyes with FFKC, 23 eyes by SMILE in 3 months post-operatively, and 23 TNC eyes. The differences in corneal biomechanics by Corvis ST among the three groups were compared. Results: There was no significant difference in CCT among the three groups, and the biomechanically corrected intraocular pressure (bIOP) did not differ significantly among the three groups (all p > 0.05). There were significant differences in most DCR parameters between pre- and post-operatively (all p < 0.05). Compared with TNC, the values of corneal deflection amplitude during the first applanation (A1DA), length at the first applanation (A1L), corneal deflection amplitude during the second applanation (A2DA), and maximum deformation amplitude (DA) decreased in 3 months after SMILE (all p < 0.05), these values increased in the FFKC (all p < 0.05). Conclusion: The majority of the DCR parameters were different among the three groups. The parameters A1DA, A1L, A2DA, and DA may be different between TNC and Post-SMILE, TNC and FFKC, and Post-SMILE and FFKC.

The utility of contact lens-assisted corneal cross-linking (CACXL) in progressive keratoconus patients with thin corneas.

To evaluate efficacy and safety of contact lens-assisted corneal cross-linking (CACXL) among progressive keratoconus patients with thin corneas. Private eye hospital. Cross-sectional study. Thirty-six eyes of 36 consecutive patients with progressive keratoconus and thinnest corneal thickness of 380-400 µm after epithelium removal were included. CACXL was performed based on use of a dextran-free isotonic (>0.1%) riboflavin solution with hydroxypropyl methylcellulose (HPMC, 1.1%) after epithelial removal and placement of a riboflavin-soaked contact lens without an ultraviolet filter on the cornea and ultraviolet irradiance. Data on best distance corrected (CDVA) and uncorrected (UDVA) visual acuity, manifest sphere (D), manifest cylinder (D), K1 (D), K2 (D), mean keratometry (D) and Kmax (D) values, endothelial cell count and mean depth of demarcation line were recorded preoperatively and at the postoperative 1-year. Post-operative 1-year data revealed significant increases in UDVA (0.23 ± 0.15 vs. 0.17 ± 0.13 D, p < 0.001) and CDVA (0.44 ± 0.18 vs. 0.36 ± 0.17 D, p < 0.001) values and a significant reduction in the mean Kmax (from 56 ± 3.3D to 55 ± 3.2 D, p < 0.001), K2 (from 49.7 ± 3.2 D to 49.52 ± 3.11 D, p = 0.049), manifest sphere (from -1.93 ± 2.21 D to -1.55 ± 2.02 D, p = 0.001) and manifest cylinder (from -2.83 ± 1.67 D to -2.39 ± 1.36 D, p < 0.001) values along with a similar endothelial cell count. The mean depth of demarcation line was mean 230 (SD17.05, range 200 to 262) at postoperative 1-month. Our findings indicate favourable 1-year postoperative outcome of CACXL in progressive keratoconus patients with thin cornea in terms of improved visual acuity and keratectasia status as well as endothelial safety.

Topography-guided corneal surface laser ablation combined with simultaneous accelerated corneal collagen cross-linking for treatment of keratoconus

Backgroundto study the outcomes of topography-guided customized excimer laser subepithelial ablation combined with accelerated CXL for progressive keratoconus.MethodsThirty-one eyes of 30 patients with progressive keratoconus were included in this prospective study. Topography-guided excimer laser ablation without refractive correction was performed. Simultaneous accelerated collagen cross-linking with ultraviolet light of 30 mW/cm2 for 4 min was followed. Uncorrected distance visual acuity (UCVA), manifest refraction, corrected distance visual acuity (CDVA), tomograghy were examined at postoperative 1, 6, and 12 months.ResultsUDVA improved slightly after surgery (P > 0.05). BSCDVA improved significantly from 0.32 ± 0.20 logMAR to 0.15 ± 0.14 logMAR at postoperative 12 months (P < 0.05). During 12-month follow-ups, there were no significant differences in manifest refraction and corneal keratometry except for maximal keratometry value of the anterior surface (Kapex), which decreased significantly from 57.23 ± 5.09D to 53.13 ± 4.47D (P < 0.05). Even though the thinnest corneal thickness decreased from 465 ± 24 μm to 414 ± 35 μm (P < 0.05), curvature asymmetry index front (SIf), keratoconus vertex front (KVf) and Baiocchi Calossi Versaci index front (BCVf) decreased significantly till postoperative 12 months (P < 0.05). Corneal higher-order aberrations and coma also decreased significantly till 12 months after surgery (P < 0.05).ConclusionsTopography-guided surface ablation without refractive correction combined with simultaneous accelerated collagen cross-linking provided good stability in refraction and corneal curvature, and also showed significant improvement in BSCDVA, corneal regularity and corneal optical quality.

A hospital-based study on clinical data, demographic data and visual function of keratoconus patients in Central China

China is a populous country but lacks epidemiological data on keratoconus (KC). The present study aimed to investigate the clinical data, demographic data, and visual function (VF) data of KC patients in Central China. A total of 524 KC eyes in 307 KC patients (217 bilateral and 90 unilateral) from Henan Eye Hospital were included in the current study. Demographic and VF data were assessed with questionnaires administered by well-trained staff during face-to-face interviews. Visual acuity value was examined by a qualified optometrist, and the clinical data were measured by professional clinicians. The distributions of sex, residence and education level of KC patients were compared by Chi-square tests, and the ratios of people wearing glasses and rigid gas permeable (RGP) lenses were compared by McNemar tests. General linear models/Chi-squared tests were used to compare the clinical and demographic data according to KC severity. Spearman’s correlation analysis was used to test the associations between the data and KC severity. The mean age at diagnosis was 20.98 ± 6.06 years, and males had a higher ratio of KC than females (P < 0.001). Patients in rural areas had a higher rate of KC than those in urban areas (P = 0.039), and the proportion of KC patients with a higher education level (above high school) was high (P < 0.001). A total of 68.40% of the patients reported eye rubbing and 3.52% had a positive family history. The percentage of people wearing glasses was higher than that of patients wearing RGP lenses (P < 0.001). The total VF score of KC patients was 69.35 ± 15.25. The thinnest corneal thickness (TCT) and stiffness parameter at the first applanation (SP-A1) values were inversely correlated with KC severity (P < 0.05). The mean, steep, and max keratometry (Km, Ks and Kmax) values, the RGP lens use and keratoplasty were positively correlated with KC severity (all P < 0.05). The total VF score of the eye with better VA decreased as the severity increased (r = − 0.21, P = 0.002). The present study comprehensively describes various associated features of KC patients from a tertiary hospital in Central China, providing a reference for understanding the characteristics of KC patients in China.

Investigation of corneal topographic and densitometric properties of Wilson's disease patients with or without a Kayser-Fleischer ring

BackgroundTo investigate the topographic measurements and densitometry of corneas in Wilson’s disease (WD) patients with or without a Kayser-Fleischer ring (KF-r) compared to healthy individuals.MethodsThis cross-sectional study included 20 WD patients without a KF-r (group I), 18 WD patients with a KF-r (group II), and 20 age-matched controls (group III). The Pentacam high resolution imaging system is used to determine corneal topographic measurements and densitometry.ResultsMean age for groups I, II and III was 25.40 ± 6.43 years (14–36 years), 25.38 ± 6.96 years (16–39 years), 23.60 ± 6.56 years (17–35 years), respectively (P = 0.623). There was no significant difference between the groups in terms of the anterior corneal densitometry values (P > 0.05), while the 6–10 mm and 10–12 mm mid stroma and the 2–6 mm, 6–10 mm, and 10–12 mm posterior corneal densitometry values in group II were significantly higher than those in groups I and III (for all values, P < 0.05). However, the 10–12 mm posterior corneal densitometry values in group I were also significantly higher than those in group III (P = 0.038). The central corneal thickness (CCT), thinnest corneal thickness (tCT), and corneal volume (CV) values in groups I and II were significantly lower than those in group III (for CCT values, P = 0.011 and P = 0.009; for tCT values, P = 0.010 and P = 0.005; for CV values, P = 0.043 and P = 0.029).ConclusionIn WD patients with a KF-r, corneal transparency decreased in the peripheral posterior and mid stromal corneal layers; for these patients, corneal transparency may be impaired not only in the peripheral cornea but also in the paracentral cornea.

Corneal Analysis with Swept Source Optical Coherence Tomography in Patients with Coexisting Cataract and Fuchs Endothelial Corneal Dystrophy

This study focused on defining the characteristic features of keratometry and pachymetry elevation maps based on swept source optical coherence tomography (SS OCT) in Fuchs endothelial corneal dystrophy (FECD) eyes with a coexisting cataract. 70 eyes of 35 patients diagnosed with FECD and a coexisting cataract and 70 control eyes were included in this prospective, controlled, observational, cross-sectional study. Features characteristic of intermediately affected eyes included an increased corneal thinnest thickness (CTT) (p = 0.01), 3 and 6 mm asymmetry (p < 0.0001), higher order Fourier indices (p < 0.05 and p ≤ 0.0001, respectively), chord µ, and a posterior Ectasia Screening Index (pESI) (p < 0.01). The lack of agreement between the anterior and posterior elevation map and a significant area of negative values in the posterior map were detected. In advanced FECD eyes, our study additionally revealed decreased posterior keratometry steep (Ks), keratometry flat (Kf), keratometry average (AvgK), eccentricity (Ecc), an increased corneal apex thickness (CAT), and decreased 3 and 6 mm posterior spherical indices (p < 0.0001 for all of the above). Characteristic features of subclinical FECD, independent of the corneal thickness, can be detected by SS OCT and should be considered during the preoperative assessment of patients with a coexisting cataract.

Detection and evaluation of Keratoconus (corneal topography) by using the image classifier techniques

In recent years, more patients were detected with corneal abnormalities. It is critical to perform diagnosis of clinical or subclinical Keratoconus accurately. The main diagnostic tool for Keratoconus is corneal topography; leading to more Laser refractive surgeries. In this paper, we recommend a novel approach which can detect Keratoconus more efficiently. The parameters derived for feature extraction are corneal volume, corneal thickness, thinnest corneal thickness, corneal area, corneal perimeter. Hybrid feed forward network along with Naive Bayes classifier is used for classification. This proposed method detects and classifies Keratoconus and the performance metrics are also evaluated using MATLAB-based simulations and finally the performance of proposed method is compared with some existing techniques.

Clinical research on corneal biomechanical changes after keratoconus collagen cross-linking

Objective To observe corneal biomechanical changes in patients with keratoconus after corneal collagen cross-linking. Methods Prospective self-control study. Twenty-three eyes of 17 patients with primary keratoconus from Jan. 2018 to Jun. 2018 in Zhengzhou Second Hospital were analyzed. The age of patients ranged from 13 to 28 years, with average of (16.4±2.8) years. All cases were treated with riboflavin/ultraviolet A (UVA)-induced rapid epithelium-off corneal collagen cross-linking. All cases were observed with Corvis ST visualized corneal biomechanical measurement instrument and followed up for 12 months. Results The best corrected visual acuity (LogMAR) after operation increased from 0.42±0.19 to 0.29±0.15 (t=-8.043, P=0.000). The equivalent spherical diopter and the maximum curvature of the anterior corneal surface were decreased (t=-4.183, -5.188, P=0.000, 0.000). The thinnest corneal thickness postoperative was decreased compared with that before operation(t=-3.984, P=0.001). The first flattening time postoperative increased (t=7.793, P=0.000). The second flattening time and the maximum indentation depth decreased (t=-9.075, P=0.000, t=-3.280, P=0.003). Conclusion The visual acuity, corneal morphology and biomechanical parameters after the rapid epithelium-off corneal collagen cross-linking in patients with primary keratoconus are ameliorated significantly. Key words: Keratoconus; Cross-linking, collagen, corneal; Biomechanics, cornea

Multiple phototherapeutic keratectomy treatments in a Chinese pedigree with corneal dystrophy and an R124L mutation: a 20-year observational study

BackgroundTo investigate the efficacy and safety of repeated phototherapeutic keratectomies (PTKs) during long-term treatment for corneal dystrophy (CD) in a Chinese pedigree carrying the R124L mutation in TGFBI.MethodsThis was a retrospective review of 20-year medical and genetic records involving five CD patients (10 eyes) from one pedigree. During this period, PTK was conducted for an eye when best-corrected distance visual acuity (BCDVA) reached > 1.0 (LogMAR), due to either primary or recurrent opacities in the cornea. All PTKs were performed by 193-nm excimer laser with or without creation of epithelial flaps. For each eye, routine measurements were conducted for the number of PTKs during follow-up, mean time to recurrence, and BCDVA pre- and post- every PTK (measurements within 3 months from each PTK). Corneal thicknesses measured after the last PTK and at the last visit were analyzed, and subjective satisfaction was assessed.ResultsGene testing revealed an R124L mutation in TGFBI. During 19.60 ± 1.78 years of follow-up, PTKs were conducted twice for three eyes, three times for six eyes, and four times for one eye. After each PTK, effective visual acuity was maintained for 3.60 ± 1.12 years before significant recurrence. BCDVA improved significantly postoperatively than preoperatively for the first PTK for each eye (p < 0.001), as well as the second (p < 0.001) and third one (p < 0.001). After the last PTK and at the final visit, the thinnest corneal thickness was 371.50 ± 56.47 μm and 358.40 ± 101.11 μm, respectively. The average subjective satisfaction score was 8.60 ± 0.89.ConclusionsMultiple repeated PTKs were effective and safe in a long-term study of CD patients with an R124L mutation in TGFBI.

Early changes in posterior corneal elevation and related factors after femtosecond laser assisted LASIK and SBK

Objective To compare the early change of posterior corneal elevation with femtosecond laser assisted laser in situ keratomileusis (FS-LASIK) and sub-Bowman keratomileusis (SBK) by Oculyzer and analyze the related factors after FS-LASIK. Methods A longitudinal observational study was designed.Ninety-one eyes of 46 patients with myopia or myopic astigmatism in the First Affiliated Hospital of Anhui Medical University from January to April in 2016 were divided into FS-LASIK group (53 eyes of 27 patients), SBK group (38 eyes of 19 patients) according to the patients' wishes and each part of corneal elevation change values were explored after FS-LASIK and SBK surgeries.The posterior corneal elevation was measured at twenty-seven measuring points along the central, paracentral, midperipheral and peripheral zone (vertex and 1, 2 and 3 mm radius) using Oculyzer preoperatively, l day, 7 days and 1 month postoperatively, respectively.Written informed consent was obtained from each patient before the surgery. Results In the FS-LASIK group, the posterior corneal elevation difference values in the central zone were (-0.924±1.859), (-1.151±1.586) and (-0.940±1.994)μm 1 day, 7 days and 1 month postoperatively, respectively.In the periphery zone, the elevation difference values were (1.046±1.667), (1.172±1.566) and (1.023±1.622)μm.In the paracentral and midperipheral zone, the cornea displayed slightly backward or forward shift.In SBK group, the posterior corneal elevation difference values of the vertex were (-0.684±1.454), (-1.053±1.723) and (-0.553±1.572)μm 1 day, 7 days and 1 month after operation, respectively.In the paracentral and midperipheral zone displayed the same trend with FS-LASIK group, and in the periphery, the values were (1.207±1.317), (1.327±1.529) and (1.208±1.415)μm.There were no statistically significant differences in posterior corneal elevation between the two surgery modes among the three time points (all at P>0.05). At 1 month postoperatively, only two independent variables, which were spherical equivalent (SE) and ablation depth (AD) entered the regression in the central and paracentral zones.Independent variables, such as central thinnest corneal thickness (TCT), SE, AD, residual bed thickness (RBT) and the ratio of AD and TCT (AD/TCT) did not enter the regression in other two areas. Conclusions The posterior corneal elevation in the central 6 mm area shows tiny change in the early stage and the variation is larger 7 days after operation in the two groups, but it does not result in keratectasia.With the increase of SE and AD, the posterior corneal elevation is more likely to be affected. Key words: Myopia; Femtosecond laser assisted laser in situ keratomileusis; Sub-Bowman keratomileusis; Posterior corneal elevation; Oculyzer

Two-year topographic and densitometric outcomes of accelerated (45\u2009mW/cm2) transepithelial corneal cross-linking for keratoconus: a case-control study

BackgroundConventional corneal cross-linking is effective for retarding the progression of keratoconus. However the long-term efficacy and safety of accelerated (45 mW/cm2) transepithelial corneal cross-linking (ATE-CXL) on progressive keratoconus (KC) treatment is not fully understood. The purpose of this study is to evaluate the 2-year changes in corneal topographic parameters and densitometry values after ATE-CXL for KC.MethodsTwenty-five progressive eyes of 25 KC patients (KC group) and 25 eyes of 25 myopes without KC (control group) were enrolled. Corneal topography and densitometry values were evaluated pre-operatively and at 6, 12 and 24 months post-operatively in the KC group.ResultsThe mean values of flat keratometry (K1), steep keratometry (K2), mean keratometry (Km), corneal astigmatism (CA), maximum keratometry (Kmax), central corneal thickness (CCT), thinnest corneal thickness (TCT), anterior corneal elevation (ACE) and posterior corneal elevation (PCE) all remained unchanged over time (all P values > 0.05). The densitometry values of the anterior, central, posterior and total layers over the annular diameters 0 mm to 2 mm (Φ0-2 mm) and Φ2–6 mm all decreased significantly (all P values < 0.05). At post-operative month 24, except for the densitometry value of the posterior layer (Φ0-2 mm), which was significantly lower than that of the control group (post hoc P = 0.010), all densitometry values obtained from the remaining locations of the KC eyes were equal to those of the control group (All post hoc P values > 0.05). Subgroups with Km ≥ 50.30D or ACE ≥35.3 μm progressed significantly when compared with those with Km < 50.30D (F = 8.167, P = 0.004) or ACE< 35.3 μm (F = 5.207, P = 0.022).ConclusionsK1, K2, Km, CA, Kmax, CCT, TCT, ACE, and PCE values may remain stable but severer KC patients tend to have poorer long-term outcomes. The densitometry values of the full corneal thickness (total layer over Φ0-2 mm and Φ2–6 mm) may decrease to normal levels at 2 years after ATE-CXL for KC.

Clinical Outcomes after Keraring Implantation for Keratoconus Management in Thin Corneas

The aim of our study was to evaluate the clinical outcomes after Keraring implantation for keratoconus in patients with thin corneas. Ten eyes from 10 patients with keratoconus, who underwent femtosecond laser-assisted Keraring implantation for keratoconus, were included in this retrospective study. Uncorrected visual acuity (UCVA), corrected visual acuity (CDVA), keratometric readings, central corneal thickness and thinnest corneal pachymetry have been evaluated preoperatively and 6 months after the Keraring implantation. UCVA, BCVA and keratometric readings improved at 6 months postoperatively. Our data showed significant keratometric amelioration and visual improvement after Keraring implantation for keratoconus in patients with thin corneas at 6 months postoperatively.

One-year follow-up of accelerated transepithelial corneal collagen cross-linking for progressive pediatric keratoconus

BackgroundKeratoconus typically presents in the teenage years and is more advanced in younger patients when compared with adults. In the present study, we aimed to assess the safety and efficacy of accelerated transepithelial corneal collagen cross-linking (ATE-CXL) in children with progressive keratoconus.MethodsIn this retrospective consecutive study, 18 eyes were enrolled from 17 pediatric patients (15 boys and 2 girls) with a mean age of 14.44 ± 1.98 years. Manifest refraction, best-corrected visual acuity (BCVA), steepest meridian keratometry (K1), flattest meridian keratometry (K2), maximum keratometry (Kmax), thinnest corneal thickness (TCT), posterior central elevation (PCE), and posterior mean elevation (PME) were measured before and after ATE-CXL. The patients were followed-up at 1, 6, and 12 months. Repeated measures analysis of variance was used for statistical analysis. P < 0.05 was considered statistically significant.ResultsThere were no complications in any case during or after ATE-CXL. BCVA improved from 0.64 ± 0.32 preoperatively to 0.69 ± 0.32 at 1-year postoperatively. The Kmax value was 56.67 ± 9.60 D before the treatment and 56.19 ± 8.55 D, 56.08 ± 8.85 D, and 55.94 ± 8.46 D at 1, 6, and 12 months postoperatively, respectively. No statistically significant differences were present in K1, K2, Kmax, PCE, and TCT before and after ATE-CXL during the 12-month follow-up (P > 0.05).ConclusionsATE-CXL is a safe and effective treatment in pediatric progressive keratoconus patients. The long-term effects need further observation.Trial registrationRetrospectively registered. Registration number: ChiCTR-OIC-16008181. Registered 29 March 2016.

Identifying more reliable parameters for the detection of change during the follow-up of mild to moderate keratoconus patients

BackgroundReaching a consensus on which parameters are most reliable at detecting progressive keratoconus patients with serial topography imaging is not evident. The aim of the study was to isolate the parameters best positioned to detect keratoconus progression using the Pentacam HR® measures based on the respective limits of repeatability and range of measurement.MethodUsing the Pentacam HR®, a tolerance index was calculated on anterior segment parameters in healthy and keratoconic eyes. The tolerance index provides a scale from least to most affected parameters in terms of measurement noise relative to that observed in healthy eyes. Then, based on the “number of increments” from no disease to advanced disease, a relative utility (RU) score was also calculated. RU values close to 1 indicate parameters best positioned to detect a change in keratoconic eyes.ResultsThe tolerance index values indicated that 36% of ocular parameters for keratoconic eyes had repeatability limits which were wider than normative limits (worse), but 28% of the ocular parameters were narrower than normative limits (better). Considering only those parameters with a RU greater than 0.95, a small number of parameters were within this range, such as corneal curvature and asphericity indices.ConclusionsThis study demonstrates that measurement error in keratoconic eyes is significantly greater than healthy eyes. Indices implemented here provide guidance on the levels of expected precision in keratoconic eyes relative to healthy eyes to aid clinicians in distinguishing real change from noise. Importantly maximal keratometry (Kmax), central corneal thickness (CCT) and thinnest corneal thickness (TCT) were highlighted as problematic indices for the follow-up of keratoconus in terms of repeatability.

Clinical results of transepithelial corneal collagen cross-linking for pediatric keratoconus

Background Keratoconus is a progressive corneal thinning and protrusion disease that develop in the age of puberty, resulting in a certain extent impairment of visual function.Corneal collagen cross-linking (CXL) increases the stiffness of the cornea through the photooxidation of ultraviolet A (UVA) and riboflavin, with the aim to postpone and prevent the progression of keratoectasia. Objective This study was to evaluate the safety and efficacy of transepithelial CXL in the treatment of pediatric keratoconus. Methods Ten eyes of 9 pediatric patients with keratoconus undergoing transepithelial CXL were enrolled from February 2010 to March 2013 in Affiliated Eye Hospital of Wenzhou Medical University, with the mean age was (15±1) years (range from 13 years to 17 years). After topical anesthesia (0.1% tetracaine) for 15 minutes, 0.5% riboflavin was applied until it was saturated in the anterior chamber, then UVA with the intensity of 3 mW/cm2 was performed on the cornea for 30 minutes.The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive error, topography, corneal thinnest thickness were measured 7 days, 1 month, 3 months, 6 months and 1 year after operation.Endothelium cell density (ECD) was measured 7 days after operative. Results The mean corneal reepithelization time was (1.4±0.8) days.The UDVA and CDVA were significantly improved from preoperative 1.02±0.16 and 0.34±0.20 to postoperative 0.77±0.18 and 0.25±0.15, respectively (t=4.251, 3.750; both at P 0.05). Stromal opacity was observed in 2 eyes 3 months and 6 months after operation, respectively. Conclusions Transepithelial CXL is safe and effective in prolonging or halting progression in adolescent keratoconus. Key words: Keratoconus; Transepithelial; Corneal collagen cross-linking; Adolescent; Ocular/Treatment outcome

Assessment of Corneal and Tear Film Parameters in Rheumatoid Arthritis Patients Using Anterior Segment Spectral Domain Optical Coherence Tomography

ABSTRACTPurpose: To study the corneal changes in rheumatoid arthritis (RA) patients in vivo, using spectral domain anterior segment optical coherence tomography (AS-OCT).Methods: A case–control study was done on 43 RA patients and 40 controls. The disease activity score (DAS28-ESR) was calculated and all participants had lower tear meniscus, corneal thickness, and epithelial thickness evaluation using AS-OCT.Results: The lower tear meniscus height (LTMH) and the lower tear meniscus area (LTMA) were significantly lower in the RA patients than in controls (p < 0.001). RA patients also had a significantly thinner central corneal thickness (p = 0.02) and their epithelium was found to be thinner in the superotemporal peripheral sector.Conclusions: The LTMH and LTMA are significantly reduced in RA patients, despite the absence of clinical diagnosis of dry eye. RA patients have thinner corneal thickness and epithelial thickness than controls, which did not correlate with either disease duration or activity.

Impact of the Femtosecond Laser in Line with the Femtosecond Laser-Assisted Cataract Surgery (FLACS) on the Anterior Chamber Characteristics in Comparison to the Manual Phacoemulsification

ABSTRACTPurpose: To assess the alterations of the anterior chamber conditions including laser flare photometry after femtosecond laser-assisted cataract surgery (FLACS) compared to the manual phacoemulsification. Methods: Data of n=70 FLACS (mean age 67.2 ± 8.9 years) and n=40 manual phacoemulsification (mean age 69.5 ± 9.6 years) were analyzed. The procedures were performed by LenSx Alcon, USA, and Alcon Infiniti Vision System, USA. The following parameters were recorded: laser flare photometry (Kowa FM 700, Japan), anterior chamber (AC) depth, AC volume, AC angle (Pentacam, Oculus Inc., Germany), lens density, pupil diameter, endothelial cell count and pachymetry. The analysis was performed preoperatively, immediately after femtosecond laser procedure and one day postoperatively. Results: Between FLACS and the phaco control group, there was a significant difference in the AC depth (p=0.023, 3.77 mm vs. 4.05 mm) one day postoperatively. The AC angle (p=0.016) showed a significant difference immediately after the femto laser treatment. The central and thinnest pachymetry and endothelial cell count did not show a significant difference between the two study cohorts (p=0.165, p=0.291, p=0.979). The phaco cohort (n=40) demonstrated a non-statistically significant difference in the flare photometry of 15.80 photons/ms one postoperative day compared to the FLACS group 26.62 photons/ms (p=0.322). Conclusion: In this study population, no evidence for an additive damage caused by the use of the femtosecond laser was demonstrated. Furthermore, no increase in the central and thinnest corneal thickness and no increased endothelial cell loss was demonstrated by the laser energy.

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.

Comparative study between oculus Wavelight Occulyzer II and Quantel Pocket II ultrasonic pachymeter in measuring central corneal thickness

Purpose The aim of this study was to compare the accuracy in measuring central corneal thickness using the oculus Wavelight Occulyzer II and Quantel Pocket II ultrasound pachymeter (UP). Patients and methods In this study, 42 eyes of 21 healthy individuals were assessed using oculus Wavelight Occulyzer II and Quantel Pocket II UP at El-Shorok Eye Hospital, Tanta, Egypt. Results In this study, the mean thinnest corneal thickness was 538.7 ± 29.35 μm with oculus Wavelight Occulyzer II and 527.6 ± 28.04 μm with Quantel Pocket II UP. Regression analysis showed that the readings of both devices are highly correlated ( r = 0.943, P = 0.001). Conclusion The readings from Wavelight Occulyzer II and UP are highly correlated. The Wavelight Occulyzer II and Quantel Pocket II UP measurements are in agreement with each other. Wavelight Occulyzer II can be used as a substitute for UP in measuring central corneal thickness.

Factors Affecting Corneal Hysteresis in Taiwanese Adults.

To investigate the correlation of various corneal hysteresis (CH) factors in Chinese adults. From January 2009 to November 2011, the healthy right eyes of a total of 292 adults were recruited into the study. Goldmann-correlated intraocular pressure (IOPG) and CH were measured using an ocular response analyzer (ORA). Central corneal thickness was measured using the ORA's integrated handheld ultrasonic pachymeter. The IOLMaster was used to obtain the ocular biometric measurements including axial length, anterior chamber depth, and keratometric values. The Pearson correlation coefficient was used to test correlations between CH and quantitative factors. The chi-square test was used to detect differences in categorical values. Longer axial length (P = 0.0001), lower IOPG (P = 0.03), older age (P = 0.003), and thinner central corneal thickness (P = 0.0001) were significantly associated with lower CH. The anterior chamber depth (P = 0.34), gender (P = 0.23), and corneal curvature (P = 0.18) had no relationship to CH. Various factors including axial length, intraocular pressure, age, and central corneal thickness can affect measurement of corneal biomechanical properties in Chinese adults. But the anterior chamber depth, gender, and corneal curvature were irrelevant to CH.