Average Central Corneal Thickness Research Articles

Changes in corneal endothelial cells after scleral-sutured fixation of intraocular lens in children with congenital ectopia lentis: a 2-year follow-up.

To investigate the changing patterns of corneal endothelial cells and the associated factors in children with congenital ectopia lentis (CEL) after scleral-sutured fixation of intraocular lens (SSFIOL). Zhongshan ophthalmic center, Guangzhou, China. Retrospective study. Patients were divided into the surgery group and the control group. Central endothelial cell density (ECD), coefficient of variation in cell size (CV), the percentage of hexagonal cells (hexagonality, HEX), average cell size (AVG) and central corneal thickness (CCT) were analyzed for both group at baseline and each follow-up visit. Clinic characteristic, ocular parameters, IOL decentration and IOL tilt of patients in the surgery group were collected. Multiple linear regression was performed to assess the potential associated factors for the postoperative changes in corneal endothelial cells in the surgery group. After 2-year follow-up, the decline of ECD was 17.8% (95%CI: -21.8 to -13.9) in the surgery group and -3.1% (95%CI: -5.2 to -1.0) in the control group(P<0.001), while the increase of AVG was 24.3%(17.1to 31.6) in the surgery group and 2.7%(1.0 to 4.5) in the control group (P<0.001). Multivariate analysis showed that AL≥24mm and WTW<12.2mm were significantly associated with greater loss of ECD (β=-241.41, 95% CI: -457.91 to -24.91, P=0.030 and β=251.63, 95% CI: 42.10 to 461.17,P=0.020, respectively) and AL≥ 24mm was significantly positively associated with the increase of AVG (β=34.81, 95% CI: 0.90 to 68.71, P=0.044). SSFIOL has a significant impact on corneal endothelium in children with CEL. More attention should be paid to monitor postoperative corneal endothelium change during long-term follow-up in CEL children, especially for those with longer AL and smaller WTW.

Corneal Endothelial Cells and Central Corneal Thickness in Pseudoexfoliation Patients

Objective: Investigating the impact of pseudoexfoliation syndrome on changes occurring in corneal endothelial cells and central corneal thickness, while assessing the influence of the degree of pseudoexfoliation on endothelial cell changes. Methods: In this analytic case-control study (Cross Sectional), the research sample included 60 patients (120 eyes) from the ophthalmic clinic attendees at Tishreen University Hospital in Latakia during the period 2023-2024. Results: The average corneal endothelial cell count was lower in the pseudoexfoliation group (2218.91±311.5 cells/mm²) compared to the control group (2559.82±290.7 cells/mm²) with a (p-value of 0.0001). The average percentage of hexagonal cells was lower in the pseudoexfoliation group (48.55±14.9 %) compared to the control group (62.32±9.7%) with a (p-value of 0.0001). No statistically significant differences were observed between the research groups in terms of average cell volume change coefficient with a (p-value of 0.9). The average cell area was higher in the pseudoexfoliation group (487.92±71.3 µm²) compared to the control group (419.94±72.2 µm²) with a (p-value of 0.003). The average central corneal thickness was lower in the pseudoexfoliation group (515.93±41.9 µm) compared to the control group (544.22±26.6 µm) with a (p-value of 0.04). We observed increased changes in corneal endothelial cells and central corneal thickness with an increase in the degree of pseudoexfoliation. Conclusion: Corneal endothelial cells and central corneal thickness are affected in patients with pseudoexfoliation syndrome, and these changes increase with severity of pseudoexfoliation.

Corneal parameters in diabetics versus non-diabetics and correlation with various blood sugar parameters.

Aim: To compare corneal parameters in diabetics versus age-group-matched non-diabetics; also, to correlate these parameters with the duration of diabetes, glycated haemoglobin (HbA1c) levels, and severity levels of diabetic retinopathy (DR). Materials and methods: A comparative study was conducted at a tertiary eye-care center from January 2020 to December 2020. Two-hundred patients (400 eyes) with type-2 diabetes (100) and age-sex-matched non-diabetics (100) were included. Corneal morphological parameters like central corneal thickness (CCT), endothelial cell density (ECD), coefficient of variance (CoV), hexagonality (6A), and average cell area were recorded by specular microscopy. These parameters were correlated with the duration of diabetes, severity of disease based upon fasting blood glucose levels, HbA1c, and grade of DR. Mean and standard deviation were calculated, and regular distribution of continuous data was tested using independent sample t-test and ANOVA. Results: Mean ECD (2447.32 ± 269.89/mm2), 6A (45.03 ± 6.71%), and IOP (15.47 ± 2.02 mmHg) changed in diabetic cases and were significantly low in diabetics, whereas, mean average cell area (413 ± 50.19 mm2), standard deviation (167.05 ± 77.91), CCT (525.81 ± 36.69) and CoV (39.84 ± 15.59%), were significantly high in diabetics. Mean CCT had insignificant variation. Subgroup analysis within diabetics showed a statistically significant reduction of ECD, cell count, and 6A with increased duration of diabetes, poor glycaemic control, and raised HbA1c. Discussion: The corneal endothelial analysis is vital in daily clinical practice and provides valuable evidence concerning the viability of corneal endothelium in various intraocular surgeries. Uncontrolled DM harms the cornea with 70% of diabetics resulting in complications like keratopathy. The study highlighted that the increased duration of diabetes raised HbA1c, and poor glycemic control negatively affected corneal morphology. Our study showed a definite reduction in ECD and 6A in diabetics compared to non-diabetics. Conclusion: A definite reduction in the corneal endothelial counts, cell density, and hexagonality was found in type-2 diabetics compared to non-diabetics. Abbreviations: DM = Diabetes Mellitus, CCT = central corneal thickness, ECC = endothelial cell counts, ECD = endothelial cell density, CoV = coefficient of variance, 6A = hexagonality, DR = Diabetic retinopathy, SD = Standard of deviation, IOP = Intraocular pressure.

Clinical Outcomes of Descemet Membrane Endothelial Keratoplasty Using a Preloaded Imported Graft.

Although the popularity of Descemet membrane endothelial keratoplasty (DMEK) is increased, there is still few clinical studies in Korea. In this study, we aimed to report the initial clinical outcomes of DMEK in patients followed up for more than 6 months. A total of 96 eyes that underwent DMEK by a single surgeon for Fuchs endothelial corneal dystrophy, pseudophakic bullous keratopathy, or other indications were evaluated for best-corrected visual acuity (BCVA), endothelial cell density (ECD), central corneal thickness (CCT), postoperative complications, and graft survival. The postoperative BCVA significantly increased compared to the preoperative BCVA by 59.4% (1.00 ± 0.77 logarithm of the minimum angle of resolution vs. 0.67 ± 0.76 logarithm of the minimum angle of resolution, p &lt; 0.001). The average preoperative ECD was 754 ± 382 cells/mm2, increasing to 1,333 ± 562 cells/mm2 at 3 months (76.8%, p &lt; 0.001), 1,334 ± 632 cells/mm2 at 6 months (76.9%, p &lt; 0.001), 1,121 ± 474 cells/mm2 at 12 months (48.7%, p = 0.024), and 972 ± 458 cells/mm2 at 24 months postoperatively (28.9%, p = 0.445). Compared to 3 months, the ECD declined by 15.9% at 12 months (p = 0.009) and 27.1% at 24 months postoperatively (p = 0.158). The average CCT was 675 ± 113 μm preoperatively, decreasing to 581 ± 102, 574 ± 101, and 594 ± 94 μm at 6, 12, and 24 months after DMEK, respectively (p &lt; 0.001 between all follow-up time points). Allograft rejection was detected in three (3.1%) and 14 eyes (14.6%) underwent retransplantation at an average of 10.1 ± 8.4 months after DMEK. DMEK is promising for maintaining corneal clarity, low postoperative complication rates, and stable graft longevity.

Evaluation of Keratoconus Disease with Tear Cytokine and Chemokine Levels Before and After Corneal Cross-Linking Treatment

ABSTRACT Objectives To compare tear cytokine and chemokine levels of keratoconus (KC) patients with controls to perceive etiology distinctly and to clarify the molecular changes after cross-linking (CXL). Methods Tear samples were gathered from 34 participants in this prospective study. Participants underwent anterior and posterior segment examinations with slit-lamp biomicroscopy. Patients were assessed by corneal topography before and 3 months after CXL. Flat (K1), steep (K2), and average keratometry (Kmean), cylinder (CYL), and central corneal thickness (CCT) values were evaluated. After 3 months from CXL, samples were re-collected, and comparisons were made with preoperative values. Results Levels of IFN-gamma, IL-8, IL-12, IL-17, TNF-α, IL-4 and IL-13 were detected higher in KC patients (p= 0.008, p= 0.047, p= 0.001, p= 0.001, p= 0.001, p= 0.001, p= 0.027, respectively). After CXL IL-4, IL-5, IL-6, IL-7, IL-8, TNF-α levels showed significant decrease (p= 0.005, p= 0.045, p= 0.010, p= 0.022, p= 0.001, p=0.002, respectively). As for the topographic measurements, postoperative CCT values were increased whereas Kmean reduced after CXL (p < 0.001, p = 0.015, respectively). (p= 0.001, p= 0.027, respectively). Conclusion Our findings imply that inflammation plays a key role in the development of KC and that this link is influenced by CXL therapy.

Central corneal thickness distribution among patients diagnosed with systemic hypertension and diabetes mellitus: The Colombian glaucoma study

Objective: To establish the Central Corneal Thickness (CCT) distribution among patients diagnosed with systemic hypertension (SH) and diabetes mellitus (DM) in six cities of Colombia. Methods: A cross-sectional study was conducted in Colombia among hypertensive and diabetic patients. This study included 2,067 subjects older than 50 diagnosed with SH and DM. Participants underwent a complete ophthalmic examination, including intraocular pressure (IOP) measurement by Goldmann tonometry, Central Corneal Thickness (CCT). The glaucoma diagnosis was confirmed by structural and functional evidence. Results: The average central corneal thickness was 538.91 microns (μm). The mean CCT of males was significantly thicker (542.43 μm) when compared with females (536.96 um) (p &lt;0.001). Glaucoma patients had thinner corneas (533.15 μm) than glaucoma suspects (535.99 μm) and non-glaucoma patients (539.15 μm) (p&lt;0.044). A decrease of approximately 2-3 um was observed for each decade of life, 50 - 60 years ( 540.50 μm ), 60 - 70 years ( 539.97 μm ), 70 - 80 years ( 537.41 μm ), older than 80 years ( 532.14 μm ) almost reaching a statistically significant value( p&lt;0.056). Mestizo subjects had thicker corneas than white (caucasian) and African - descendants; 538.29 μm, 539.29 um, 531.05 μm, respectively (p &lt;0.012). Patients with Intraocular Pressure (IOP) lower than 15 mmHg had thinner corneas than patients with IOP between 15 - 21 mmHg and higher than 21 mmHg; 536.92 μm, 543.41 μm, 559.50 μm, respectively (p: 0000). Conclusions: CCT is thicker in males compared to females. Glaucoma patients had thinner corneas than glaucoma suspects and non-glaucoma patients. Older patients (&gt;80 years) had thinner corneas than younger patients. Mestizo subjects had thicker corneas than white (caucasian) and African - descendants. Patients with lower Intraocular Pressure (IOP) had thinner corneas than patients with higher IOP mmHg.

Prospective In Vitro Comparison of Kerasave and Optisol-GS Corneal Storage Solutions.

The aim of this study was to compare the performance of Kerasave and Optisol-GS for hypothermic corneal storage for 14 days. This study was a prospective laboratory investigation. Mate corneas were recovered into Kerasave or Optisol-GS (27 pairs) and stored at 2°C to 8°C for 14 days. Corneas were evaluated by trained eye bank technicians, and study parameters were compared between the initial and final evaluations. Endothelial cell density (ECD), hexagonality (HEX), and coefficient of variation (CV) were evaluated by specular microscopy, and central corneal thickness (CCT) was examined by optical coherence tomography after 1, 3, 7, and 14 days of storage. Corneal transparency was scored using slit lamp examination at days 1 and 14. Average ECD, HEX, and CV for the Kerasave (2653 ± 303 cells/mm 2 , 57 ± 4%, and 36 ± 3%) and Optisol-GS (2623 ± 306 cells/mm 2 , 57 ± 5%, and 36 ± 4%) groups were not significantly different at day 1. There was also no difference at any other study time points (all P > 0.05). ECD did not significantly change from day 1 to day 14 in either group ( P > 0.05), but a statistically significant change in HEX and CV was observed between day 1 and day 14 in both groups ( P < 0.01). Average CCT measured at day 1 for corneas stored in Kerasave was 622 ± 49 μm and those stored in Optisol-GS was 580 ± 35 μm ( P < 0.01). The difference in CCT measurements was not significantly different at day 14 (Kerasave: 674 ± 46 μm vs. Optisol-GS: 647 ± 58 μm, P > 0.05). Corneal transparency was not significantly different between the 2 groups at day 1 or day 14. The corneal quality and clinically relevant parameters including ECD, endothelial morphometry, and corneal transparency were not different in corneas stored in Kerasave or Optisol-GS for 14 days. The initial difference in CCT between the 2 groups decreased at day 14. These results demonstrated that Kerasave corneal storage solution preserves the corneal endothelium similarly to Optisol-GS.

Pseudo‐double anterior chamber following deep anterior lamellar keratoplasty (DALK) with type 2 bubble formation

AbstractPurpose: To describe the clinical features and natural history of pseudo‐double anterior chamber (DAC) after Deep Anterior Lamellar Keratoplasty (DALK) in cases with Type 2 bubbles.Methods: An observational case series of three patients with Type 2 bubbles. All patients had advanced keratoconus and underwent DALK with a ‘big bubble’ technique. A cohesive ophthalmic viscosurgical device (OVD) was used to maintain separation between the posterior stroma and Descemet's Membrane (DM). A small optical window (5 mm) was created in the centre of the posterior stroma to reduce the risk of perforation. No perforations were observed intraoperatively. Patients were followed up for 1 year with serial anterior segment optical coherence tomography (AS‐OCT).Results: A characteristic pattern of DM detachment was observed postoperatively on AS‐OCT. Separation was maximal in the periphery and minimal in the centre under the optical window, creating a ‘W' sign. Despite separation between the posterior stroma and DM, stromal deturgescence continued at a normal rate with a return to normal central corneal thickness in 1 month. Complete reattachment of the DM, with resolution of the ‘W' sign, was seen by 6 months in all cases.Conclusions: Pseudo‐DAC following DALK appears to result from retained OVD in the interface between the DM and stroma. This phenomenon is distinctly different from a classical DAC, which results from a perforation in DM. The pseudo‐DAC does not result in corneal oedema and stromal thickening and restoration of corneal clarity occurs without apposition of the DM. Use of a small optical window and OVD cushion in cases of type 2 bubble is a useful technique to prevent intraoperative perforation. Small amounts of retained OVD will spontaneously resorb. We believe excessive irrigation and aspiration in the space between the DM and the posterior stroma, in an effort to remove all OVD, may risk perforation of DM and this case series suggests it is unnecessary.

Comparison of Central Corneal Thickness and Lamina Cribrosa Thickness in Ethnic Indians and Ethnic Malays as Predictors of Glaucomatous Optic Neuropathy

Background: Glaucoma poses a public health problem because it is the second leading cause of blindness after cataracts. A thinner central corneal thickness (CCT) is also a contributor to the development of primary open-angle glaucoma (POAG). Lamina cribrosa (LC) is a structure of the optic nerve head (ONH). LC structural changes such as thinning, posterior displacement, and connective tissue deficiency are associated with the mechanism of retinal nerve fiber layer (RNFL) thickness damage, leading to glaucomatous optic neuropathy.&#x0D; Methods: Cross-sectional analytic observational study. A total of 36 eyes from 36 research subjects participated in this study. Data analysis was carried out using SPSS version 25. Then, univariate and bivariate analyzes were carried out to see the difference in CCT and LC thicknesses.&#x0D; Results: The average CCT in ethnic Indians is 514.33 ± 14,142 μm and in ethnic Malays, 542.06 ± 17,234 μm. In this study, there were differences in the average CCT in Indian ethnicity and Malay ethnicity, which was statistically meaningful with a p-value = 0.000.&#x0D; Conclusion: There are differences in the average central corneal thickness and lamina cribrosa thickness in ethnic Indians compared to ethnic Malays, where the central corneal thickness and lamina cribrosa thickness in ethnic Indians are thinner than ethnic Malays.

Prospective analysis of Artisan aphakia intraocular lens implantation for nontraumatic ectopia lentis in children

To report long-term outcomes of iris claw aphakia intraocular lens (IOL) implantation for nontraumatic ectopia lentis (EL) in children. In this prospective study, children who underwent Artisan Aphakia IOL placement were included if they have a minimum of 1-year follow-up after implantation. Main outcome measures were: best-corrected distance visual acuity, reoperations, change in central corneal thickness (CCT), and corneal endothelial cell counts (ECC). The Artisan Aphakia IOL was implanted in a total of 76 eyes of 43 patients (68 eyes of 34 patients with EL). 56 eyes of 28 patients have been followed long enough to meet the inclusion criteria for this report. The average age at Artisan Aphakia IOL implantation was 11.1 years (range of 2-20 years). Average follow-up was 3.59 years, and 23% of patients have >5 years' follow-up. Mean best-corrected visual acuity improved from 0.36 (20/46) to logMAR 0.18 (20/30) after implantation (P = 0.02). Five reoperations were needed in 4 patients, 3 (7%) related to post-implantation trauma. Average preoperative CCT was 580 μm; estimated mean increase in CCT at the 5-year postoperative visit was 11.9 μm higher (P = 0.047). Average preoperative ECC was 3178 cells/mm2; estimated mean loss of ECC at the 5-year postoperative visit was not significantly different from zero (187.7 cells/mm2 [P = 0.102]). The Artisan Aphakia IOL, used in the absence of capsular support, had an acceptable safety profile in our patients.

Axial Elongation During Short-Term Accommodation in Myopic and Nonmyopic Children.

PurposeAxial length increases during accommodation in adults and children; however, refractive error group differences are conflicting and have not been explored in pediatric populations. This study aimed to evaluate differences in accommodation-induced axial elongation between myopic and nonmyopic children.MethodsA range of ocular biometric measurements were captured during brief accommodation tasks (0, 3, 6, and 9 D) using a Badal optometer mounted to a noncontact optical biometer (Zeiss IOLMaster 700). Reliable measurements were captured for 15 myopic and 15 age- and sex-matched nonmyopic children. The average central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), anterior segment length (ASL), vitreous chamber depth (VCD), and axial length (AL) were determined for each accommodation stimulus. Raw measurements of AL and VCD were corrected for the estimated error associated with LT increases during accommodation.ResultsAll biometric parameters, except CCT, changed significantly during accommodation (all P < 0.001). Myopic children exhibited significantly greater accommodation-induced axial elongation than nonmyopic children (P = 0.002) at the 3, 6, and 9 D accommodation stimuli, with a mean difference of 7, 10, and 16 µm, respectively (all pairwise comparisons, P ≤ 0.03). The changes in all other biometric parameters were not different between the refractive error groups (P ≥ 0.23).ConclusionsAccommodation-induced axial elongation was greater in myopic than nonmyopic children. This finding could support a potential mechanism linking near work, axial elongation, and myopia development in children or may reflect greater susceptibility to accommodation-induced axial elongation in children with established myopia.

Random Forest Algorithm-Based Ultrasonic Image in the Diagnosis of Patients with Dry Eye Syndrome and Its Relationship with Tear Osmotic Pressure.

The study was to investigate the diagnostic value of ultrasound based on the random forest segmentation algorithm for dry eye disease and the relationship between dry eye degree and tear osmotic pressure. Specifically, 100 patients with dry eye syndrome were selected as the research subjects, and they were divided into group A (conventional ultrasonic detection) and group B (ultrasonic detection based on the random forest segmentation algorithm), with 50 patients in each group. An ultrasonic measurement was used as the gold standard to evaluate the effect of ultrasonic diagnosis. The degree of dry eye was determined by Ocular Surface Disease Index (OSDI) Questionnaire and DR-1 tear film lipid layer (TFLL) test. The tear osmotic pressure was measured, and the relationship between the degree of dry eye disease and the tear osmotic pressure was analyzed. The results showed that the ultrasonic imaging effect and each index based on random forest algorithm were better than the traditional graph cut algorithm. The average central corneal thickness (CCT) values of group A and group B were (27.8 ± 30.6) μm and (29.1 ± 30.9) μm, respectively. 95% confidence interval was 22.7-34.2 μm. In patients with moderate dry eye, the average CCT measured in group A was (−6.31 ± 2.82) μm, and that in group B was (−6.45 ± 3.06) μm. The 95% confidence interval of the difference between the two is −7.66~−5.43 μm. In patients with severe dry eye, the average CCT was (−3.78 ± 1.13) μm in group A and (−7.09 ± 2.05) μm in group B (P < 0.05). The 95% confidence interval of the difference between the two is −7.05~ −5.11 μm. In spearman correlation analysis, tear osmotic pressure increased with dry eye severity. There was a statistically significant difference between the moderate and the severe (P < 0.05). Tear osmotic pressure can be a rapid diagnostic index of dry eye severity. Ultrasound based on the random forest segmentation algorithm has high clinical application value in the diagnosis of dry eye syndrome.

Corneal biomechanics in a pediatric population

AbstractPurposeThe purpose of the study is to explore the relationship between biomechanical corneal parameters and axial length in a pediatric population.MethodsWe conducted a prospective study that included 82 eyes from 41 pediatric patients. All patients were submitted to a complete ophthalmologic examination that included autorefractometry (before and after pharmacological cycloplegia), slit lamp and fundus examination, ocular tonometry. Additionally, the patients underwent examination with Ocular Response Analyzer (Reichert Ophthalmic Instruments Inc., Depew, NY) to determine corneal hysteresis (CH), corneal resistance factor (CRF) and with Aladdin biometer (Topcon, Tokyo, Japan) to determine axial length (AL) and central corneal thickness (CCT). Statistical analysis was performed using IBMSPSS Statistics 26.ResultsOur study included 82 eyes, from 41 patients (63.41% female, 36.59% male). The average age was 13.29 years old (12.92 in females, 13.93 in males). Average CH, CRF, and spherical power, respectively, were similar between sexes: 12.30 mmHg, 12.47 mmHg, −0.70 D respectively in females, 12.89 mmHg, 13.31 mmHg and −1.27 D respectively in males. Mean AL and CCT are larger in males than in females, in a statistically significantmanner. Average AL is 23.69 mm in females, 24.52 mm in males (p = 0.007) and average CCT is 0.558 mm in females and 0.583 mm in males (p = 0.003). We also found a statistically significant moderate negative correlation between CH and AL in the pediatric population (Pearson’s r of −0.350, p = 0.001), and also in both sexes (Pearson’s r of −0.419, p = 0.002 in females and −0.437, p = 0.016 in males).ConclusionsOur study reveals that in the pediatric population, at similar age, males have a thicker central cornea and longer axial length. Furthermore, in these patients, a high axial length is correlated to a low corneal hysteresis. Further studies are needed to explore these data and to confirm these findings in adults.

A cross sectional study on evaluating the corneal endothelial cell density and central corneal thickness in eyes with primary glaucoma.

This study aims at evaluating glaucoma-induced damage to the corneal endothelium and the effect of central corneal thickness (CCT) on the intra-ocular pressure (IOP) measurement in patients newly diagnosed with primary glaucoma. It is a hospital-based cross-sectional study involving 60 newly diagnosed primary glaucoma patients >18 years. They underwent fundus examination, four-mirror gonioscopy, and perimetry for confirming the diagnosis. Evaluation and analysis of corneal endothelial cell density and CCT were performed. Chi square test was performed to find out the association between glaucoma, corneal endothelial cell density, and CCT. Evaluation of 60 patients revealed that by age distribution, the corneal endothelial cell density was lower in the 51-65 year age group and an age-related decrease in corneal endothelial cell density and CCT was found in newly diagnosed primary glaucoma patients. The mean CCT was 525 micrometers in patients with IOP between 20 to 40 mm Hg and 528 micrometers in patients with IOP between 41 to 60 mm Hg. The mean corneal endothelial cell density was 2361 cells/mm2 in primary open-angle glaucoma (POAG) and 2284 cells/mm2 in primary angle-closure glaucoma (PACG). The mean CCT was 525 micrometers in POAG and 528 micrometers in PACG. The corneal endothelial cell density was lower in patients with PACG when compared with POAG, and the average CCT showed no significant difference in POAG and PACG patients. However, CCT was increased in patients with a higher intra-ocular pressure. The corneal endothelial cell density was lower in patients with a high intra-ocular pressure.

7-Year Results of SMILE for High Myopia: Visual and Refractive Outcomes and Aberrations.

To evaluate the 7-year visual, refractive, and optical outcomes following small incision lenticule extraction (SMILE) for high myopia and myopic astigmatism. Sixty-nine eyes (69 patients) undergoing SMILE between March 2011 and January 2012 at Aarhus University Hospital were included. Preoperative, 3-month, 3-year, and 7-year evaluation included: manifest refraction and uncorrected (UDVA) and corrected (CDVA) distance visual acuities, total corneal refractive power (TCRP), average keratometry (Km), aberrations, and central corneal thickness (CCT). Preoperative spherical equivalent averaged -7.53 ± 1.18 diopters (D). Twenty-seven eyes were targeted emmetropia. In the emmetropic eyes, the postoperative logMAR UDVA remained stable (P = .11). When including all eyes, UDVA became worse from 3 to 7 years (3 months: 0.050 ± 0.16 logMAR; 3 years: 0.044 ± 0.21 logMAR; 7 years: 0.131 ± 0.29 logMAR; P < .027), whereas CDVA remained stable (3 months: -0.07 ± 0.09 logMAR; 3 years: -0.09 ± 0.08 logMAR; 7 years: -0.09 ± 0.08 logMAR, P > .99). At 7 years, 59.4% and 81.2% were within ±0.50 and ±1.00 D of target refraction, respectively. Average refractive regression was significant from 3 months to 7 years (-0.34 ± 0.69 D) and from 3 to 7 years (-0.25 ± 0.41 D, P < .05). After exclusion of three outliers with high myopic correction (< 9.63 D) and considerable regression (<-1.50 D), the average regression over 7 years was -0.25 ± 0.49 D (P = .004) with no significant change from 3 to 7 years (P = .069). Average CCT, TCRP, and anterior Km significantly increased (P < .001), whereas the posterior Km and total corneal aberrations remained stable (P > .092). The long-term visual outcome remained stable after SMILE, but with an average regression of -0.34 D over 7 years. A minor group with high myopic correction exhibited considerable refractive regression years after SMILE. [J Refract Surg. 2021;37(10):654-661.].

Comparison of Central Corneal Thickness Measured by Tono-pachymetry and Ultrasound Pachymetry

Purpose: We compared the accuracy of central corneal thickness (CCT) measurements according to CCT measured by noncontact Tono-pachymetry and ultrasound pachymetry (USP). Methods: CCT was measured in 90 eyes of 90 subjects by two optometrists. The CCT measurements were compared and the correlations between the measurements were analyzed. To evaluate whether the measurements varied depending on CCT, the subjects were classified into three groups according to CCT (group 1: thin thickness group; group 2: medium thickness group; and group 3: thick thickness group). The differences in CCT obtained by the two devices (△CCT = Tono-pachymetry-USP) were compared and analyzed among the three groups. Results: The average CCT measurements by Tono-pachymetry and USP were 523.26 ± 32.93 μm and 527.08 ± 37.33 μm, respectively. CCT by Tono-pachymetry was significantly thinner than by USP (△CCT= -3.82 ± 15.34, p = 0.020). The two measurements were strongly correlated (r = 0.912, p &lt; 0.001). The △CCT values were 5.40 ± 12.13 μm in group 1, -6.37 ± 15.07 μm in group 2, and -10.50 ± 14.39 μm in group 3 (p &lt; 0.001). Conclusions: CCT measured by tono-pachymetry was thinner on average compared to the value measured by USP and the differences in measurements between the two devices were different according to CCT. The thinner the CCT, the thicker the measurement, and the thicker the CCT, the thinner the measurement. Therefore, this trend should be considered when interpreting tono- pachymetry results in clinical practice.

Association between visual field damage and corneal structural parameters

The main goal of this study is to identify the association between corneal shape, elevation, and thickness parameters and visual field damage using machine learning. A total of 676 eyes from 568 patients from the Jichi Medical University in Japan were included in this study. Corneal topography, pachymetry, and elevation images were obtained using anterior segment optical coherence tomography (OCT) and visual field tests were collected using standard automated perimetry with 24-2 Swedish Interactive Threshold Algorithm. The association between corneal structural parameters and visual field damage was investigated using machine learning and evaluated through tenfold cross-validation of the area under the receiver operating characteristic curves (AUC). The average mean deviation was − 8.0 dB and the average central corneal thickness (CCT) was 513.1 µm. Using ensemble machine learning bagged trees classifiers, we detected visual field abnormality from corneal parameters with an AUC of 0.83. Using a tree-based machine learning classifier, we detected four visual field severity levels from corneal parameters with an AUC of 0.74. Although CCT and corneal hysteresis have long been accepted as predictors of glaucoma development and future visual field loss, corneal shape and elevation parameters may also predict glaucoma-induced visual functional loss.

Changes in corneal thickness after vitrectomy-Implications for glaucoma practice.

To evaluate changes in central corneal thickness (CCT) following vitrectomy. All consecutive old and new patients referred to glaucoma services for possible secondary glaucoma after vitrectomy and who had undergone corneal pachymetry between July 2013 to June 2020, were included. The eye that developed elevated intraocular pressure (IOP) and was diagnosed clinically as glaucoma after vitrectomy, was labelled as the "affected" eye. The contralateral eye of the patient with normal IOP and no history of vitrectomy was labelled as the "control" eye. The difference in CCT in the affected eye and the contralateral control eye (ΔCCT) and CCT were compared between different age groups. Correlation of CCT in the affected eye with age, diagnosis, type of surgery done, lens status and pre-existing glaucoma was done using multivariate regression analysis. Of 127 eyes of 120 patients (M:F = 85:35), the average CCT in the affected eye was significantly higher than the unaffected contralateral control eye (p<0.0001). The ΔCCT in eyes presenting at an age <25 years was higher (median 582, 497-840) than those that presented later (median 518, 384-755), p <0.0001, with maximum ΔCCT seen in eyes that had undergone vitrectomy at age<12 years. The CCT in the affected eye was significantly higher in aphakic eyes (588±81.6 microns) than in pseudophakic eyes (552±79.03 microns), p = 0.03. On multivariate analysis, age<25 years remained as a significant influencer of CCT in the affected eye (β = -1.7, p<0.001, R2 = 28.3%). Young age group<25 years are more prone to corneal remodelling and CCT changes after vitrectomy.

Relationship Between Central Corneal Thickness and Ganglionic-Inner Plexiform Cell Layer and Retinal Nerve Fibre Layer Thickness in Normal Subjects.

PurposeTo determine the relationship between central corneal thickness (CCT), ganglionic cell-inner plexiform layer thickness and macular nerve fibre layer (RNFL) thickness as measured by optical coherence tomography in a cohort of healthy subjects.MethodsSixty healthy eyes from 60 subjects were included in this study. All subjects had a standard slit-lamp examination and optical coherence tomography. Central corneal thickness was measured using the Optopol spectral domain optical coherence tomography (SD OCT) machine (version 7.2.0). A linear mixed effects model was used to assess the relationship between central corneal thickness (CCT) and ganglionic cell-inner plexiform layer thickness and macular retinal nerve fibre layer thickness (RNFL).ResultsSixty healthy eyes from 60 subjects were included in this study. The average age was 41.8 years (±20.6 years). There were 22 males (37%) and 38 females (63%). The average central corneal thickness was 525.2 ± 35.1 µm (451–601) µm. The average macular retinal nerve fiber layer thickness was 28.9 ± 2.5 µm (23–38µm), and the average ganglionic cell-inner plexiform layer thickness was 88.6 ± 6.3 µm (75–110 µm). We found no statistically significant relationship between central corneal thickness and ganglionic cell-inner plexiform layer thickness (p=0.983) nor with macular RNFL (p =0.285).ConclusionIn this cohort of healthy subjects, there was no statistically significant relationship between central corneal thickness and ganglionic cell-inner plexiform layer thickness or with macular retinal nerve fibre layer thickness.

The pattern of central corneal thickness in patients attending a Tertiary Hospital in Dar-Es-Salaam

Background: Central Corneal Thickness (CCT) is an indicator of corneal health status as well as being an essential tool in assessment and management of corneal diseases. It is an important factor in the diagnosis and management of glaucoma as it affects the measurement of intraocular pressure. However, the pattern of central corneal thickness in our population is not known. Our study aimed to describe the CCT measurements and their variation with age and sex among patients attending the eye clinic at Muhimbili National Hospital (MNH), in Dar es Salaam, Tanzania. Methodology: A hospital-based descriptive, cross-sectional study used convenient sampling to recruit adult patients aged 18 years and above, presenting to the MNH between August 2016 and January 2017.Visual acuity assessment, Goldman applanation tonometry and CCT assessment using an ultrasound pachymeter were performed. Patients with previous intraocular surgery were excluded. Results: A total of 398 patients (208 males and 190 females) were recruited. The mean CCT was 526.64±38.30 µm; being 523.99±38.20 µm for males and 529.7±38.3 µm for females. 226 (56.85%) had CCT of less than 520 µm.There was no statistically significant difference in CCT between gender. The proportion of patients with thinner CCT increased with increasing age from 25.8% in those &lt; 30 years to 75% in those aged 71years and above. The mean CCT decreased with increasing age with P-value&lt;0.001. Conclusion: The average CCT in patients attending Muhimbili National Hospital is 526.64 µm (SD 38.30) which is generally thin, inversely proportion to age and similar that of other Africans and African-Americans. This finding has implications for the management of glaucoma in this population.