Terms Of Central Corneal Thickness Research Articles

Effect of antiglaucomatous eye drops on corneal endothelium

First choice therapy for reducing the intraocular pressure in context of glaucoma remains the applications of eye drops. Longterm exposure to topical therapy can clearly have an impact on the ocular surface, but as the medications penetrate through the cornea and are present in humour aqueous, also on all other layers of cornea, including corneal endothelium. In general, none of the medications from the standard pharmacological groups influences significantly an otherwise healthy corneal endothelium in an eye with glaucoma or ocular hypertension – be it in terms of central corneal thickness, be it in terms of endothelial cell density and morphology, be it for beta blockers, carbonic anhydrase inhibitors, pilocarpine, alpha2 agonists or prostaglandin analogues. The situation changes in diseased corneas, such as in Fuchs endothelial dystrophy, where topically applied carbonic anhydrase inhibitors can lead to increase in corneal thickness. Benzalkonium chloride has been proven toxic for corneal endothelial cells in vitro. However, in the daily practice and under real life circumstances, it is from the specific point of view on the corneal endothelium still not clear whether using non‐preserved topical glaucoma medications is an absolute imperative. One separate topic here is also a group of Rho‐kinase inhibiting topical medications. Apart from new mechanisms of action for reducing the intraocular pressure, this group of medications has also a direct influence on the corneal structures – from cornea verticillata on the epithelium corneal level, to mobilizing peripheral endothelial corneal cells as a possible therapeutic path for Fuchs endothelial dystrophy. One part of the lecture will address also these issues.

Üveitik Hastalarda Korneal Değişikliklerin Non-Kontakt Speküler Mikroskopi ile Değerlendirilmesi: Retrospektif Çalışma

Objective: To demonstrate the changes in specular microscopy between uveitic eyes and healthy eyes. Material and Methods: A retrospective study included 66 patients followed in the Uvea clinic of Selcuk University between 2015-2018. The right eyes of all patients were evaluated. The right eye data of 37 healthy individuals were used as the control group. The patients were divided into subgroups anterior, intermediate, and posterior uveitis. Specular microscopy measurements were made with Confo Scan 4. Comparisons were made between the groups in terms of endothelial cell density (ECD), pleomorphism (%), polymegatism (%), central corneal thickness (CCT), and intraocular pressure (IOP). A p-value less than 0.05 was considered significant. Results: The mean age was 33.71±15.29 in the uveitis and 37.78±13.17 in the control group (p=0.432). There was a significant difference between the groups in terms of ECD, pleomorphism and polymegatism (all groups; p<0.01). No significant difference was found in terms of CCT and IOP (respectively; p=0.812, p=0.381). In the subgroup analysis, a significant difference was found between anterior, intermediate and posterior uveitis groups in terms of ECD (respectively; p=0.020, p=0.018). However, no significant difference in other groups (p=0.999). In comparison with healthy eyes of patients with monocular uveitis were significant differences in all parameters (all groups; p<0.01). Conclusion: It is seen that ECD decreases, pleomorphism and polymegatism increase in patients with uveitis. This result showed the importance of preventing sequelae with early treatment in patients with uveitis. Speccular or confocal microscopy scanning is important in uveitic patients scheduled for intraocular surgery.

The effect of hyperbaric oxygen therapy on corneal endothelial structure and anterior segment parameters

Purpose To assess the effect of hyperbaric oxygen therapy (HBOT) on corneal endothelial structure and anterior segment parameters in healthy eyes. Methods 17 eyes of 17 patients who were scheduled to receive HBOT for other than ophthalmologic indications were investigated in this prospective study. Central corneal thickness (CCT) and corneal endothelial properties were evaluated using a specular microscope. Endothelial cell density (ECD), average cell area (AVG), coefficient of variation in cell size (CV), percentage of hexagonal cells (HEX), CCT, intraocular pressure (IOP), spherical equivalent (SE), axial length (AL) and anterior chamber depth (ACD) values were measured before the HBOT, after the 1st session, and after the 20th session of therapy. Results 47% of the patients (n = 8) received HBOT because of avascular necrosis, 35% (n = 6) due to sudden hearing loss, 12% (n = 2) for diabetic foot, and 6% (n = 1) for wound infection. The mean IOP was 14,80 mmHg before HBOT, 14,20 mmHg after the 1st session, and 13,73 mmHg after the 20th session. The mean ACD was 3,38 mm before HBOT, 3,34 mm after the 1st session, and 3,16 mm after the 20th session. Although the mean IOP and ACD decreased after HBOT sessions, it was not statistically significant (p > 0.05). A significant reduction was observed in SE values after 20 sessions of HBOT compared to the values measured before HBOT (p = 0,009). The mean ECD was 2572,53 ± 261,51 cells/mm2 before HBOT, 2554,47 ± 236,13 after the 1st session, and 2563,13 ± 226,92 after the 20th session. When the corneal properties measured before and after HBOT sessions were compared, no significant difference was found in terms of CCT, ECD, AVG, CV, and HEX (p > 0.05). Conclusion We observed no significant change in CCT, corneal endothelial layer properties, and anterior segment morphology after the 1st session, and after the 20th session of HBOT. Although HBOT reduced IOP and ACD, it was not statistically significant. HBOT may lead to a significant decrease in SE values after the 20th session.

Manual DSEK in patients with Pseudophakic Bullous Keratopathy: Viable option in resource limited settings

Evaluation of success rate of manual DSEK in terms of central corneal thickness and BSCVA in patients of PBK. : Prospective, non-comparative, interventional study of 18 patients of PBK, who underwent manual DSEK between June 2021 to May 2022 with minimum six months to maximum 15 months post-operative follow up. DSEK lenticule was prepared by manual dissection. Push in technique with 26 G needle was used for graft insertion. Preoperative and post-operative CCT and BSCVA were measured and compared. : Preoperative central pachymetry in patients (n=18) was (832±162) μm which significantly reduced in the post operative period. The mean thickness of lenticule on day 1 post op was 203±93.5μm which became 156±76 μm (p =.0436) at 6 months and remained almost same till last follow up. Pre operative BSCVA ranged from HM to 2/60 in these 18 patients which was improved in 16/18 eyes post DSEK. Eighty eight percent (15/17) patients had regained BSCVA of 6/60 to 6/12. In early post operative period, complications noted were, partial detachment of lenticule and pupillary block glaucoma which were managed accordingly.: Manual DSEK is feasible, low-cost widely accessible alternative to DSAEK/DMEK for patients of PBK with good visual outcome in resource limited settings.: Manual DSEK has short learning curve and it’s training should be imparted to corneal surgeons for better outcome in PBK and other causes of endothelial decompensation.

Dumansız Tütünün Ön Segment Parametreleri Üzerindeki Akut ve Kronik Etkisinin Değerlendirilmesi

Aim: To evaluate the acute and chronic effects of smokeless tobacco (ST) on the anterior segment parameters using optical biometry. Material and Method: The comparative study included 53 right eyes of 53 subjects (study group), who used ST and 54 right eyes of 54 healthy subjects without ST (control group). Following a full ophthalmological examination, baseline measurements were taken with optical biometry and these measurements were repeated at 5, 30 and 60 mins after using ST. Central corneal thickness (CCT) (µm), anterior chamber depth (ACD) (mm), lens thickness (LT) (mm), pupillary diameter (PD) (mm), and axial length (AL) (mm) were measured. Result: No statistical difference between the control group and study group in terms of CCT, AL, ACL and LT (p=0.771, p=0.706, p=0.546, p=0.984, respectively) however, PD values were statistically significantly different (p=0.040) in baseline measurements. In the study group, similary, no statistically significant difference was determined between the measurements taken before and after ST use in respect of CCT, AL, ACD, and LT (p=0.660, p=0.058, p=0.344, p=0.059, respectively). The changes in the PD value with the use of ST were determined to be statistically significant (p<0.01). Thus, the difference in PD value was found to be statistically significant between 5 and 30 mins, between 5 and 60 mins, and between 30 and 60 mins after ST use (p<0.01, p<0.01, p<0.01 respectively). Conclusion: ST use did not show any acute and chronic effect on CCT, AL, ACD and LT. However, there was seen to be a significant effect on PD.

Evaluation of anterior segment parameters with Pentacam in children with poorly-controlled type 1 Diabetes Mellitus without diabetic retinopathy.

To determine the effect of abnormal glucose metabolism on the cornea, lens, anterior chamber volume (ACV), and anterior chamber depth (ACD) in children with poorly-controlled type 1 diabetes mellitus (DM) without diabetic retinopathy (DR). After the complete ophthalmologic examination of children with poorly-controlled (glycosylated hemoglobin [HbA1c] >7.0 %) type 1 DM without DR and age-matched healthy subjects (control group), the central corneal thickness (CCT), keratometry (K) values (Kmean front and back, and Kmax), radius (R) values (Rmin front and back), corneal volume (CV), ACD, ACV, pupil diameter, mean lens density (MLD), lens density standard deviation (LD SD), and maximum lens density (LD max) were measured using Pentacam High Resolution. Endothelial cell density was measured using a specular microscope. The results were assessed and compared between the two groups. There were 60 patients (38 boys and 22 girls) in the DM group and 30 (14 boys, 16 girls) in the control group. There were considerable differences between the groups in terms of CCT, CV, ACD, MLD, LD SD and LD max, and Kmean back. Further, there was a positive correlation between HbA1c and MLD, LD SD, CV, and CCT in patients with DM. The results of our study demonstrate that poorly-controlled type 1 DM without DR affects the cornea, ACD, and LD based on anterior segment measurements taken with a Scheimpflug camera. CCT, CV, LD SD, and MLD values may be parameters that can be used to follow-up patients with type 1 DM.

The effect of long-term hydroxychloroquine use on the corneal endothelium in patients with systemic lupus erythematosus.

To evaluate the effect of long-term effects of hydroxychloroquine (HCQ) use on the corneal endothelium in patients with systemic lupus erythematosus (SLE). The study included 30 eyes of 15 patients who used HCQ for at least five years and were followed up in the rheumatology clinic for SLE and 29 eyes of 15 patients newly diagnosed with SLE who had not taken any medication. All patients underwent complete ophthalmologic examinations, central corneal thickness measurements, endothelial cell counts and endothelial morphological examinations by specular microscopy. The mean age was 41.25 ± 6.89years in group 1 and 41.81 ± 5.78years in group 2 (p = 0.737). The mean corneal endothelial cell density was 2662 ± 184cells/mm2 in group 1 and 2649 ± 315cells/mm2 in group 2 (p = 0.843). The percentage of cell hexagonality was 46.6 ± 11.8% in group 1 and 48.7 ± 13.8% in group 2 (p = 0.625). A difference was noted in endothelial cell variation in both groups, at 36.7 ± 6.9% in group 1 and 39.9 ± 6.2% in group 2 (p = 0.057) but not statistically significant. No difference was observed between the two groups in terms of central corneal thickness. The duration of HCQ use was negatively correlated with hexagonality (r = -0.564, p = 0.001) CONCLUSION: Long-term use of HCQ in SLE patients had no negative effect on endothelial cell density and cell variation, but a negative correlation existed between the duration of HCQ usage and hexagonality.

The acute effects of single cup of coffee on ocular biometric parameters in healthy subjects

PurposeTo evaluate ocular biometric changes in healthy subjects after caffeine consumption from a cup of coffee. MethodsA total of 36 subjects were included in this prospective observational study. Axial length (AL) and anterior segment parameters including aqueous depth (AD), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT) were measured with optic biometry, Lenstar LS 900 (Haag-Streit, Inc., Koeniz, Switzerland) before and 1 and 4 h after ingesting a cup of coffee (60 mg caffeine/100 mL). ResultsMean age of the participants was 30.05 ± 7.43 years (range, 19–45). At baseline, 1st, and 4th hour, AL values were 23.9 ± 1.04 mm, 23.91 ± 1.04 mm, and 23.89 ± 1.04 mm, respectively, and no significant difference was observed (P>0.05). At baseline, 1st, and 4th hour, AD values were 3.06 ± 0.3 mm, 3.11 ± 0.3 mm, and 3.09 ± 0.3 mm, and ACD values were 3.6 ± 0.32, 3.66 ± 0.31, and 3.64 ± 0.31, respectively. AD and ACD values were significantly greater than baseline at 1st and 4th hours following coffee ingestion. Coffee intake caused a significant reduction in LT, compared with baseline and at the 1st and 4th hours which were 3.76 ± 0.28 mm, 3.69 ± 0.32 mm, and 3.72 ± 0.27 mm, respectively. No statistically significant difference was determined in between the 3 measurements in terms of CCT (P>0.05). ConclusionCaffeine causes a significant increase in AD and ACD and a significant decrease in LT following oral intake, for at least 4 h.

Lentiviral Vector-Mediated Expression of Exoenzyme C3 Transferase Lowers Intraocular Pressure in Monkeys.

Primary open-angle glaucoma (POAG) is considered a lifelong disease characterized by optic nerve deterioration and visual field damage. Although the disease progression can usually be controlled by lowering the intraocular pressure (IOP), therapeutic effects of current approaches do not last long. Gene therapy could be a promising method for persistent treatment of the disease. Our previous study demonstrated that gene transfer of exoenzyme C3 transferase (C3) to the trabecular meshwork (TM) to inhibit Rho GTPase (Rho), the upstream signal molecule of Rho-associated kinase (ROCK), resulted in lowered IOP in normal rodent eyes. In the present study, we show that the lentiviral vector (LV)-mediated C3 expression inactivates RhoA in human TM cells by ADP ribosylation, resulting indisruption of the actin cytoskeleton and altered cell morphology. In addition, intracameral delivery of the C3 vector to monkey eyes leads to persistently lowered IOP without obvious signs of inflammation. This is the first report of using a vector to transduce the TM of an alive non-human primate with a gene that alters cellular machinery and physiology. Our results in non-human primates support that LV-mediated C3 expression in the TM may have therapeutic potential forglaucoma, the leading cause of irreversible blindness in humans.

Effect of the Rigid Gas-Permeable Contact Lens Use on the Endothelial Cells in Patients With Keratoconus.

To compare the changes in the corneal endothelial cells of both the patients with keratoconus who use rigid gas-permeable (RGP) contact lens and who do not use any contact lens with healthy population. Thirty-three patients with keratoconus who use RGP contact lenses (group 1), 20 patients with keratoconus who do not use any contact lens (group 2), and 40 healthy controls were included in the study. Changes in the corneal endothelial cells of all patients were evaluated using a noncontact specular microscope. Endothelial cell density (ECD), coefficient of variability (CV), hexagonal cell percentage (%HEX), and central corneal thickness (CCT) of the patients were evaluated in the study. In the groups 1, 2, and 3, the mean ECD was 2,420.8±247, 2,579.5±240, and 2,589.5±271 cells/mm, the mean CV was 357±9, 34±7, and 34±6, the mean %HEX was 54.3±13, 59.1±14, and 57.4±10, and the mean CCT was 508±33, 504±43, and 561±34 μm, respectively. There was no significant difference between the groups in terms of ECD, CV, and %HEX. Although significant differences between the groups 1 to 3 and groups 2 to 3 in terms of CCT were detected (P=0.001 and P=0.004, respectively), no significant difference was observed between the groups 1 and 2. Although significant difference was found between the groups 1 to 2 and normal population in terms of CCT, no difference was detected between all the groups in terms of the other parameters. In this study, we report that long-term use of RGP contact lens in patients with keratoconus had no effect on the corneal endothelial cells.

Novel application of In Vivo Micro-Optical Coherence Tomography to assess Cornea scarring in an Animal Model

This pilot study uses a micro-optical coherence tomography (micro-OCT) system with ~1 μm axial resolution specifically to image the cornea and corneal scars in vivo. We used an established murine corneal scar model by irregular phototherapeutic keratectomy in ten C57BL/6 mice, with serial imaging using the micro-OCT and compared to anterior segment (AS-OCT) (RTvue, Optovue, Fremont, CA) before and after scar induction. Main outcome was agreement between the AS-OCT and micro-OCT using Bland-Altman plots (95% limits of agreement, LoA).We analysed 10 control eyes and 10 eyes with corneal scars and found that there was good agreement between AS-OCT and micro-OCT (P > 0.05) LOA: lower limit −14 µm (95% CI: −19 to −8.8 µm) upper limit 23 µm (95% CI: 18 to 28.5 µm) in terms of central corneal thickness. There was also good agreement between AS-OCT and micro-OCT in terms of corneal scar measurements (P > 0.5; correlation coefficient >0.99) LOA lower limit −2.1 µm (95% CI: −2.8 to −1.5 µm); upper limit 1.8 µm (95% CI: 1.1 to 2.4 µm). Our pilot study suggests that this novel in vivo micro-OCT imaging technique was able to measure central corneal thickness and scar thickness in agreement with current AS-OCT techniques.

Corneal endothelial alterations in alcohol dependence syndrome

Background/aimsTo evaluate the corneal endothelial changes in patients with alcohol dependence syndrome (ADS).MethodsA total of 322 corneas of 322 subjects were studied, and two groups were formed. The first, the...

Comparison of central corneal thickness and endothelial cell measurements by Scheimpflug camera system and two noncontact specular microscopes.

To investigate the correlation of Scheimpflug camera system and two noncontact specular microscopes in terms of central corneal thickness (CCT) and corneal endothelial cell morphology measurements. One hundred eyes of 50 healthy subjects were examined by Pentacam Scheimpflug Analyzer, CEM-530 (Nidek Co, Ltd, Gamagori, Japan) and CellChek XL (Konan Medical, California, USA) via fully automated image analysis with no corrections made. Measurement differences and agreement between instruments were determined by intraclass correlation analysis. The mean age of the subjects was 36.74±8.59 (range 22-57). CCTs were well correlated among all devices, with having CEM-530 the thinnest and CellChek XL the thickest measurements (intraclass correlation coefficient (ICC)=0.83; p<0.001 and ICC=0.78; p<0.001, respectively). Mean endothelial cell density (ECD) given by CEM-530 was lower than CellChek XL (2613.17±228.62 and 2862.72±170.42 cells/mm2, respectively; ICC=0.43; p<0.001). Mean value for coefficient of variation (CV) was 28.57±3.61 in CEM-530 and 30.30±3.53 in CellChek XL. Cell hexagonality (HEX) with CEM-530 was higher than with CellChek XL (68.70±4.16% and 45.19±6.58%, respectively). ECDs with CellChek XL and CEM-530 have good correlation, but the values obtained by CellChek XL are higher than CEM-530. Measurements for HEX and CV differ significantly and show weak correlation. Thus, we do not recommend interchangeable use of CellChek XL and CEM-530. In terms of CCTs, Pentacam, CEM-530 and CellChek XL specular microscopy instruments are reliable devices.

The evaluation of central corneal thickness and intraocular pressure in conjunction with tear IGF-1 levels in patients with acromegaly.

To compare the central corneal thickness (CCT), intraocular pressure (IOP), and tear insulin-like growth factor 1 (IGF-1) levels between patients with acromegaly and a control group and to evaluate the possible effect of tear IGF-1 and duration of the disease on CCT and IOP. We included 31 patients with acromegaly (study group) and 40 age- and sex-matched controls in the study. Patients with acromegaly were divided into 2 subgroups based on disease status (active/inactive). All participants underwent complete ophthalmologic evaluation including CCT and IOP values. Basal tear samples were collected from both groups and tear IGF-1 levels were measured. The CCT, IOP, and tear IGF-1 levels were compared between groups and subgroups and the association between tear IGF-I levels and ocular parameters (CCT, IOP) and disease duration were also evaluated. Central corneal thickness, IOP, and tear IGF-1 levels did not show a significant difference between study and control groups. We also did not find a significant difference in terms of CCT, IOP, or tear IGF-1 levels between subgroups of patients. Correlation analysis did not show an association between the duration of disease and tear IGF-1 levels with CCT or IOP. There was no significant difference in tear IGF-1 levels between patients with acromegaly and controls. Additionally, there was no correlation between disease duration and tear IGF-1 levels with CCT or IOP levels. This lack of association may suggest that tear IGF-1 levels might not have an effect on CCT or IOP findings in patients with acromegaly.

Effects of Smoking on Central Corneal Thickness and the Corneal Endothelial Cell Layer in Otherwise Healthy Subjects.

The effects of smoking on central corneal thickness (CCT), corneal endothelial cell density (ECD), and morphology were evaluated in otherwise healthy subjects. The study included 103 current smokers and 106 healthy nonsmoking subjects without any eye disease apart from refractive errors. Endothelial cell density, percentage of hexagonality, and coefficient of variation (CV) in cell size were measured using noncontact specular microscopy. Central corneal thickness was measured by ultrasound pachymetry. The mean age of participants in the nonsmoker group was 31.4 ± 5.1 years (18-60) and 33.0±9.1 years (18-58) in the current smoker group. The mean CCT value was 523.7±34 μm in the nonsmoker group and 518.5±37 μm in the smoker group. The mean ECD, CV, and percentage of hexagonality values were 2,881±293.7 cells per square millimeter, 32.5±6%, and 56.6±11% in the nonsmoker group, and 2,681±323.9 cells per square millimeter, 33.4±5%, and 55.5±10% in the smoker group, respectively. Although there was no difference between the groups in terms of CCT, CV, and percentage of hexagonality values, a significant difference was determined in the case of ECD values[ZERO WIDTH SPACE][ZERO WIDTH SPACE] (P<0.001). The smoker group comprised 67 light smokers (65.0%) and 36 (35.0%) heavy smokers. Between these groups, there was no statistically significant difference in the mean values of CCT, ECD, CV, and the percentage of hexagonality. Although cigarette smoking has no effect on cell polymorphism and polymegethism, the results suggest that smoking reduces endothelial cell count.

Central Corneal Thickness in Children With Diabetes

To evaluate the central corneal thickness in children with diabetes and to determine the association between diabetes mellitus-related variables and central corneal thickness. Fifty-nine patients (mean age: 13.2 years) with diabetes mellitus and 38 controls (mean age: 10.3 years) were compared in terms of central corneal thickness assessed by ultrasound pachymetry. The effects of age, gender, the duration of diabetes mellitus, the mean and current hemoglobin A1C (HbA1C) level, and fasting blood sugar level on central corneal thickness were investigated. Analysis of covariance and multivariate regression analysis were used for statistical analysis. The analysis of covariance with age as the covariant indicated that the diabetes mellitus group had significantly increased central corneal thickness (mean: 576.9+/-41.8 microm) compared with the control group (mean: 521+/-16.6 microm) (P<.0001). A multivariate regression model evaluating the effects of age, gender, duration of diabetes mellitus, fasting blood glucose, and the mean and current HbA1C levels on central corneal thickness was statistically significant (F(4,54)=3.33, P=.016). The results indicated that the current HbA1c value was the only significant predictor for central corneal thickness (B=0.29, t=2.13, P=.038) (B=9.7 microm per 1% HbA1C and B=13.3 microm per 1% HbA1C for right and left eyes, respectively). Diabetic patients have a significantly increased (approximately 55 microm) central corneal thickness compared with healthy controls. Current HbA1C value, which is the marker of metabolic control of the disease, is the only disease-related variable that predicts a higher central corneal thickness.

Newer Hard Contact Lens Materials

Despite the tidal wave of hydrophilic lenses onto the market over the past nine years, hard lenses refuse to die or fade away. In fact, in Australia, it appears that hard lenses now account for about 30 per cent of lenses made. Over the past three years some new non-hydrophilic (i.e.<5 per cent water) materials have become available in reasonable quantities, each claiming improved physiological performance on the eye. On paper and in vitro these claims appear to be substantiated but the acid test is in vivo. This paper is the outline of such an investigation. Three non-hydrophilic materials, PMMA, modified PMMA (BP Flex), and a CAB material were used, and the corneal response in terms of central corneal thickness and oxygen uptake on removal noted. Each subject was fitted with an optimum fitting lens, a slightly tight lens, and a very tight lens.