Central Corneal Area Research Articles

Guttae Morphology After Cultured Corneal Endothelial Cell Transplant in Fuchs Endothelial Corneal Dystrophy

Whether guttae in Fuchs endothelial corneal dystrophy (FECD) can be removed by polishing without Descemet stripping and whether postoperative maintenance of reduced guttae can be achieved through cultured corneal endothelial cell (CEC) transplant therapy are critical issues to be addressed. To investigate the decrease of guttae through polishing degenerated CECs and abnormal extracellular matrix (ECM) without Descemet stripping and to observe the behavior of guttae following cultured CEC transplant. This case series prospective observational study was conducted in a hospital outpatient clinic setting. Between December 2013 and January 2019, 22 eyes with corneal endothelial failure caused by FECD received cultured CEC transplant therapy at Kyoto Prefectural University Hospital. Of these, 15 eyes were consistently monitored at the same central corneal area during the preoperative phase, as well as in the early (within 1 year) and late (after 3 years) postoperative phases. The images from these phases were categorized into 3 groups: typical guttae, atypical guttae, and no guttae. Cultured CEC transplant therapy. Proportion of guttae in the observable area was measured, comparing the early and late postoperative phases for each group. The mean age of the patients at the time of surgery was 69 years (range, 49-79 years). All 15 eyes exhibited the presence of confluent guttae preoperatively (100%). Among these, 3 of 15 eyes belonged to male patients. The early postoperative phase of guttae morphologies was classified into 3 groups: 5 eyes with typical guttae, 7 with atypical guttae, and 3 with no guttae. The decrease in the number of these guttae was achieved by surgical procedures. The median percentage of guttae in the typical guttae, atypical guttae, and no guttae groups was 41.8%, 44.4%, and 16.2%, respectively, in the early phase, and 42.2%, 38.2%, and 18.8%, respectively, in the late phase. The findings demonstrate that in some cases of FECD, guttae can be removed by scraping and polishing abnormal ECM and degenerated CECs, while preserving the Descemet membrane. Furthermore, cultured CEC transplant resulted in no increase in guttae for up to 3 years, providing insights into surgically eliminating guttae.

Visual rehabilitation with mini scleral contact lenses in scarred corneas

Purpose: To present a case series of patients with corneal scars who were successfully fitted with mini scleral contact lenses (mSCL).Methods: Case series study.Results: Six eyes of six patients with corneal scars were fitted with mSCLs. All scars were situated in the visual axis within the scotopic pupillary zone. The sizes of the scars varied, with the smallest being confined to a central corneal area (case 5) and the largest covering the entire visual axis (case 2). In addition to compromising corneal transparency, these scars also induced significant corneal irregularities, especially in cases 1, 3, and 4. The average corrected distance visual acuity (CDVA) with spectacles was 20/80, with a range of 20/200 to 20/40. With the use of mSCLs, CDVA improved to an average of 20/25, ranging from 20/40 to 20/16. The mean visual acuity improvement observed was five optotype lines, with a range of 3 to 7 lines.Conclusion: Corneas with scars often exhibit increased higher-order aberrations (HOA), and affected patients not only experience reduced vision but also suffer from seriously reduced optical quality and optical phenomena such as photophobia. Utilizing mSCLs in such individuals can significantly enhance visual acuity and improve optical side effects resulting from corneal opacity and irregularity.

Deep anterior lamellar keratoplasty following thermokeratoplasty assisted epikeratophkia: A novel two-stage one-graft method to treat acute corneal hydrops.

To evaluate the clinical effects of deep anterior lamellar keratoplasty (DALK) using a single graft after thermokeratoplasty assisted epikeratophakia for the treatment of acute corneal hydrops. This novel surgical procedure was performed on seven eyes of seven patients between 2019 and 2020. The procedure combines a first-stage surgery of thermokeratoplasty assisted epikeratophkia with intracameral sterile air injection and a second-stage surgery of DALK using the same corneal graft for both procedures. Main outcome measures included pre- and postoperative corrected distance visual acuity (CDVA) and anterior segment optical coherence tomography (AS-OCT) parameters. Corneal transparency, epithelization, and the presence of neovascularization, were evaluated at the 1-year follow-up visit. Corneal edema resolved rapidly in six of the seven cases. The mean central corneal thickness was significantly reduced from baseline to 1 day, 1 week, 1 month, and 2 months after the first-stage surgery (P < 0.0001). At a mean of 2.1 ± 0.7 months after the first-stage surgery, DALK was successfully performed in all cases. Six months later, the mean central corneal thickness was 611 ± 31 μm and the mean thickness of the recipient's residual stroma bed was 20 ± 6 μm at the central corneal area. Mean LogMAR CDVA improved from 1.74 ± 0.34 at baseline to 0.20 ± 0.11 after DALK (P < 0.0001). No postoperative complications appeared in our case series during the 1-year observation period. Very good visual results were obtained with a novel technique (thermokeratoplasty assisted epikeratophakia followed by DALK using the same corneal graft) in the treatment of acute corneal hydrops.

Specular microscopy of the corneal endothelial cells of bovines: an ex vivo study.

The endothelium is the most posterior layer of the cornea and is essential for maintaining corneal transparency. Due to variations in corneal endothelial parameters among different species, knowledge of the normal parameters for each species is crucial. To evaluate the corneal endothelium of bovines using contact specular microscopy. Twenty eyeballs from 10 male Brangus (Bos taurus) aged 24 months were evaluated. Contact specular microscopy was performed on the central corneal area. The analyzed parameters were endothelial cell density (ECD) and endothelial cell morphology. The ECD in the central area was 1,277 cells/mm2. Regarding the morphology, mainly cells with six (74.3%), five (14.7%) and seven sides (10%) were found. There were no significant differences in ECD and morphology between left and right eyes. Contact specular microscopy facilitated the analysis and measurement of corneal endothelial parameters in bovines. The data obtained will serve as a reference for the analysis of bovine corneal endothelium.

Agreement Between Predicted and Actual Measured Ablation Depth After FS-LASIK Using Different Rotating Scheimpflug Cameras and OCT.

PurposeTo compare the predicted ablation depth (AD) with the postoperatively measured corneal ablation depth (postop-AD) at central, paracentral, and midperipheral locations using two rotating Scheimpflug analyzers and a Fourier-domain optical coherence tomographer in eyes that underwent femtosecond laser-assisted LASIK (FS-LASIK).MethodsThe values of corneal thickness were measured preoperatively and postoperatively at one and three months. The difference between preoperative and postoperative was defined as postop-AD. Measurements were performed at the corneal vertex and mid-peripheral area. The mid-peripheral corneal thickness was measured at the superior, inferior, nasal, and temporal locations at a distance of 1.0 or 2.5 mm from the corneal vertex. The predicted AD was calculated by ORK-CAM software (Schwind eye tech-solutions GmbH, Kleinostheim, Germany), and the difference between the predicted AD and postop-AD was defined as Δ-AD. Paired t-test analysis was employed to evaluate the differences, agreement was assessed by the Bland-Altman method.ResultsForty-two eyes of 42 patients were investigated. At one month, the predicted AD in the central and paracentral areas was underestimated by the Pentacam HR (Oculus, Wetzlar, Germany), Sirius (Costruzione Strumenti Oftalmici, Florence, Italy) and RTVue OCT (Optovue Inc., Freemont, CA, United States), whereas Δ-AD was negative as established by all devices and predominantly statistically significant. The Δ-AD values approximated zero at three months. The mean difference of Δ-AD at three months at the corneal vertex was 0.67 ± 9.39 mm, −7.92 ± 9.05 mm and −1.36 ± 8.31 mm, respectively. The mid-peripheral measurements had positive values at one month and even more highly positive at three months (with statistically significant differences in most of the cases). The agreement between the predicted and postop-AD was moderate with all devices, but slightly better with RTVue.ConclusionThe predicted AD seems to be underestimated in the central and paracentral corneal area and overestimated in the mid-periphery.Translational RelevanceThe study could help to partly explain and prevent the refractive errors after FS-LASIK.

Utilization rate and usage patterns of phakic and pseudophakic donor corneas recovered by the Singapore Eye Bank.

PurposeTo compare the utilization rate and usage patterns of pseudophakic and phakic donor corneas recovered by the Singapore Eye Bank.MethodsRecords of local donor corneas recovered by the Singapore Eye Bank from 2012 to 2017 were examined. Corneas that were deemed suitable for clinical use were stratified into phakic and pseudophakic groups. We examined the basic demographic pattern of both groups and the initial type of surgery/ies that the corneas were suitable for based on tissue parameters such as time from harvesting, stromal clarity, the clear central corneal area, the presence of Descemet’s membrane tears or defects, and endothelial cell density and quality. We also identified the types of corneal grafts that the corneas were eventually used for; Penetrating Keratoplasty (PK), Anterior Lamellar Keratoplasty (ALK), Endothelial Keratoplasty (EK). Finally, the overall utilization rates for each group were determined.ResultsA total of 986 corneas deemed suitable for transplant were analyzed, 908 (92%) were phakic and 78 were pseudophakic (8%). The average age of pseudophakic donor corneas was (65 ± 8 yrs. old) and there was a slight male preponderance for both groups (55%). Age adjusted analysis of pseudophakic corneas showed the endothelial cell density (ECD) (mean: 2327 ± 47.1 cells/mm2) and clear area (mean: 7.0 ± 0.7 mm) were lesser than phakic corneas. The percentage of pseudophakic corneas that were of EK standard (ECD >2500 cells/mm2) were lower compared to phakic corneas (37% and 77% respectively, p < 0.001). There was significant correlation between previous cataract surgery and the endothelial cell count of the donor corneas (p < 0.001), and regression analysis also showed a strong association of ECD with cataract surgery in reference to non-cataract surgery (-478.8 (95% CI-576.9 to -380.7). The overall utilization rate for pseudophakic corneas was 58% compared to that of phakic corneas at 83%. The most common reason for pseudophakic corneas not to be utilized was due to the presence of Descemet’s membrane (DM) tears or defects under the main or side port incision created during phacoemulsification (30%). Phakic corneas were used primarily for optical grafts 84% (mainly EK) while pseudophakic corneas were used mostly for therapeutic/tectonic grafts 47% (mainly ALK or patch grafts).ConclusionCompared to phakic donor corneas, pseudophakic corneas generally have lower overall tissue quality leading to lower uptake by surgeons and lower utilization rates. Eye banks must continuously refine their donor acceptance criteria and engage surgeons to optimize utilization of each recovered tissue.

The Biomechanical Response of the Cornea in Orthokeratology.

Orthokeratology has been widely used to control myopia, but the mechanism is still unknown. To further investigate the underlying mechanism of corneal reshaping using orthokeratology lenses via the finite element method, numerical models with different corneal curvatures, corneal thicknesses, and myopia reduction degrees had been developed and validated to simulate the corneal response and quantify the changes in maximum stress in the central and peripheral corneal areas during orthokeratology. The influence of the factors on corneal response had been analyzed by using median quantile regression. A partial eta squared value in analysis of variance models was established to compare the effect size of these factors. The results showed central and peripheral corneal stress responses changed significantly with increased myopia reduction, corneal curvature, and corneal thickness. The target myopia reduction had the greatest effect on the central corneal stress value (partial eta square = 0.9382), followed by corneal curvature (partial eta square = 0.5650) and corneal thickness (partial eta square = 0.1975). The corneal curvature had the greatest effect on the peripheral corneal stress value (partial eta square = 0.5220), followed by myopia reduction (partial eta square = 0.2375) and corneal thickness (partial eta square = 0.1972). In summary, the biomechanical response of the cornea varies significantly with the change in corneal conditions and lens designs. Therefore, the orthokeratology lens design and the lens fitting process should be taken into consideration in clinical practice, especially for patients with high myopia and steep corneas.

Effects of topical application of 0.4% oxybuprocaine hydrochloride ophthalmic solution and 1% ropivacaine hydrochloride on corneal sensitivity in rats

The aim of the present study was to determine and compare the degree and duration of corneal anesthesia following topical application of 0.4% oxybuprocaine hydrochloride ophthalmic solution and 1% ropivacaine hydrochloride treatment in healthy rats. A randomized, blinded, crossover study was conducted on 20 healthy adult Wistar rats, following complete physical and ophthalmological examination. Baseline corneal touch threshold (CTT) was determined in the central corneal area of both eyes with a Cochet–Bonnet aesthesiometer, in mm filament length. Oxybuprocaine was randomly applied to one eye and 0.9% sterile sodium chloride solution was instilled into the contralateral eye. Subsequent CTT measurements were performed in both eyes 5 minutes after topical application and at 5-minute intervals thereafter for 75-minutes in the anesthetized eye. Following a 2-week washout period, this protocol was repeated with ropivacaine. Quantitative data were summarized as mean ± standard deviation, median and inter-quartile range (Q1–Q3). Repeated measures data were analyzed over time and between treatments using Friedman test and Wilcoxon signed-rank test with Bonferroni adjustment (p < 0.05). Baseline CTT values were 60 mm in all eyes. With oxybuprocaine, CTT values decreased significantly for 65 minutes (0–55 mm; p = 0.002) when compared with baseline; the maximal anesthetic effect (no blink response at 5 mm filament length) was maintained for up to 15 minutes (p < 0.0001). With ropivacaine, CTT values were significantly lower than baseline for 30 minutes (0–55 mm; p = 0.002), with a maximal anesthetic effect recorded at 5 minutes in 18 eyes (p < 0.0001). Oxybuprocaine induced a significantly lower CTT than ropivacaine (p = 0.002) from 10 to 65 minutes following topical application. Both anesthetic agents induced significant corneal anesthesia; however, oxybuprocaine provided a greater and longer anesthetic effect, making it more suitable for potentially painful ophthalmologic procedures.

Morphology of Endothelial Cells from Different Regions of the Swine Cornea

Background: The corneal endothelium is a monolayer of polygonal cells which constitute the last layer of the cornea. The integrity of this layer is critical to cornea transparency. The characterization of normal corneal endothelial morphology is important not only to clinical evaluation but also to selection of areas of the cornea with better quality to be employed as donor tissue. The aim of the present study was to evaluate the morphology of endothelial cells from different regions of the swine cornea after alizarin red staining using optical microscopy.Materials, Methods &amp; Results: Twenty-four healthy eyes from 12 swine Large White breed, with 14-month-old, males or females obtained from a licensed Brazilian commercial slaughterhouse were studied. Immediately after humane slaughter, the eyes were enucleated and submitted to ophthalmic examination. Eyes with signs of diseases of the anterior segment were excluded. The cornea, with 3 mm of the sclera, was removed and placed on a glass microscope slide with the endothelial side up. Four radial incisions were made in the periphery of the cornea to better accommodate the cornea on the microscope slide. Alizarin red was diluted in isotonic solution (0.2 g/100 mL) and the pH was adjusted to 4.2 with hydrochloric acid. Three drops of alizarin red were placed on the corneal endothelium. After 90 s, the dye was removed from the cornea with balanced saline solution. The corneal endothelium was examined and photographed using an optical microscope. All evaluations were performed by the same investigator. Photomicrographs were taken of central, superior, inferior, nasal and temporal corneal areas. Parameter studied included endothelial cell morphology. For the statistical analysis, was employed the ANOVA variance test (repeated measures). Differences were considered statistically significant at P &lt; 0.05. Normal endothelium cells were mainly hexagonal (83.7%), pentagonal (7.45%) and heptagonal (8.8%), with a minimal number of cells of other shapes present. There were no significant statistical differences in the proportion of the morphology and the different regions of the cornea (P = 0.31).Discussion: Different techniques are available for the analysis of corneal endothelium, including mainly scanning electron microscopy, specular microscopy and optical microscopy. The analysis of the morphology of corneal endothelium with an optic microscope after staining with alizarin red has been described as an effective, rapid and cost-efficient method, since this dye blends the borated cells, allowing identification. In the present study, using optical microscopy and coloration with alizarin red it was possible to explore and to obtain images of the swine endothelium of all regions of the cornea. The analysis of the cellular morphology or the percentage of hexagonal cells are among the main parameters used to evaluate the health of the corneal endothelium. In this study, the endothelium had the predominance of the hexagonal shape in all regions studied. In swine, there are no studies evaluating the shape of the endothelial cells in the five different regions of the cornea. This study has demonstrated that the parameters evaluated in swine did not differ significantly between the various places of the cornea.

Limbal rebound tonometry: clinical comparisons and applications

The accuracy of contact tonometry may be compromised in cases with disorders affecting central corneal bio-mechanical properties. This study examined the reliability of rebound tonometry (RT) on the area of corneo-scleral limbus, instead of the conventional central corneal area, and the correlation of findings with ocular biometric parameters. This is a prospective cross-sectional study performed at the Department of Ophthalmology of the University Hospital of Heraklion, in Crete, Greece. Consecutive cataract surgery candidates without concomitant ocular pathology, apart from cataract, were included. RT was performed on the central cornea (central RT, CRT) as well as on the limbus and scleral spur area (limbal RT, LRT). Findings were correlated with Goldmann applanation tonometry (GAT) as well as axial length (AL), central corneal thickness (CCT), and corneal curvature (CC) measurements. LRT readings were significantly correlated with central CRT as well as with GAT readings, whereas respective correlations with other parameters examined were not statistically significant. LRT may be used as an alternative tool in clinical practice to determine intraocular pressure when conventional devices and techniques might be inadequate or unreliable.

Three-Dimensional Construction of a Rabbit Anterior Corneal Replacement for Lamellar Keratoplasty.

The aim of this study was to construct a rabbit anterior corneal replacement for transplantation using acellular porcine corneal matrix (APCM) and rabbit epithelial or stromal cells. APCM was prepared from fresh porcine cornea treated with 0.5% (wt./vol.) sodium dodecyl sulfate (SDS) solution. The expanded stromal cells were first injected into APCM parallel to its surface and were cultured in a shaking culture system for 7 days to obtain the stromal construct. Next, corneal epithelial cells were cultured on the stromal construct surface for another 7 days to obtain rabbit anterior corneal lamella. The construct had a phenotype similar to that of normal cornea, with high expression of cytokeratin 3 in the epithelial cell layer and vimentin in the stromal cells. More importantly, the construct integrated well with the implanted host corneal tissue, and the implant cornea maintained transparency in the 6-month follow-up, although there was a slight haze in the central corneal area. The endothelium in the surgery cornea had a similar cell density and mosaic pattern with normal cornea as shown by confocal laser corneal microscopy, and the regenerated corneal epithelial cells on the implant surface showed a similar morphology to that of natural epithelial cells. These results demonstrate that the constructed anterior corneal replacement exhibits an excellent biological property for lamellar keratoplasty and might be a possible alternative to human corneal tissue in the future.

Deep anterior lamellar keratoplasty using the same graft after epikeratophakia for the treatment of acute corneal hydrops in keratoconus

Objective To evaluate the clinical effects of deep anterior lamellar keratoplasty (DALK) using the same graft after epikeratophakia for the treatment of acute corneal hydrops in keratoconus. Methods A consecutive 7 cases (7 eyes) with acute corneal hydrops in keratoconus in our department were retrospectively analyzed. Same corneal graft was used to perform the first stage epikeratophakia combined with C3F8 anterior chamber injection. About 6 months after the first surgery, the secondary stage deep anterior lamellar keratoplasty combined with air anterior chamber injection was performed. The best corrected visual acuity, healing status of the anterior and posterior corneal surface, anterior segment optical coherence tomography parameters, and corneal endothelial cells density were recorded. Results The central corneal thickness was (1764±256) μm before the treatment, and it was (778±147) μm, (604±23) μm, (579±20) μm and (525±19) μm at the time points of 1 d, 7 d, 1 and 6 months after the first stage surgery respectively. An average (6.1±1.3) months after the first stage surgery, the second stage DALK was performed. The descemet's membrane at the central area could be fully exposed in 3 eyes. Slow liquid exudations in the deep corneal stroma near the descemet's membrane were found in the other 4 eyes during stroma dissection. DALKs were successfully performed in all the 7 cases. Double anterior chambers were found in 2 eyes 1d after DALK. The whole corneal thicknesses were (781±57) μm, (581±49) μm and (521±19) μm at 7 d, 1 and 3 months after DALK respectively. Three months later, the thickness of the receptors' residual stroma bed was (21±11) μm at the central corneal area. At the end of the follow-up, the BCVA(LogMAR)was 0.11±0.03. Conclusion Novel curative effect was found in the treatment of acute corneal hydrops in keratoconus by deep anterior lamellar keratoplasty using the same graft after epikeratophakia. Key words: Acute corneal hydrops, keratoconus; Epikeratophakia; Keratoplasty, deep anterior lamellar; Anterior segment optical coherence tomography; Descemet's membrane

Age, Maximum Cup Depth, Central Corneal Thickness, Disc Area and Mean Defect in Patients with Open Angle Glaucoma and Ocular Hypertension

Purpose: The main objective was to analyze the relationship between maximum cup depth (MCD), mean defect (MD), central corneal thickness (CCT), age and disc area, in patients with ocular hypertension (OHT) and primary open angle glaucoma (POAG). Methods: Cross-sectional study of patients diagnosed with OHT and POAG. Visual fields were obtained using an Octopus 300 analyzer, TOP strategy. MCD and disc area were obtained using a Heidelberg Retina Tomograph. Results: The study sample comprised 234 eyes of 143 patients, 91 women and 52 men, mean age 63.55 years (SD 10.49). Mean values were: MCD 0.52 mm (SD 0.27), MD 2.78 dB (SD 5.02), CCT 543.5 μm (SD 36.63), IOP 16.73 mmHg (SD 2.93), and disc area 2.01 mm2 (SD 0.39). A significant correlation was observed between MCD and age in patients under 60 years, between MCD and disc area, and between MD and disc area. Conclusions: Our study showed a correlation between MCD and age which was significant in patients under 60 years of age, between MCD and disc area and between MD and disc area, suggesting that the larger the disc area, the greater the MCD and the MD in patients with OHT and POAG.

Intravital imaging of the cellular dynamics of LysM-positive cells in a murine corneal suture model

BackgroundCorneal suturing is a surgical procedure used in patients with corneal trauma or transplants. It was reported that endogenous neutrophils are brightly labelled in gene-targeted mice expressing enhanced green fluorescent...

Local Variability of Parameters for Characterization of the Corneal Subbasal Nerve Plexus

Purpose: The corneal subbasal nerve plexus (SNP) offers high potential for early diagnosis of diabetic peripheral neuropathy. Changes in subbasal nerve fibers can be assessed in vivo by confocal laser scanning microscopy (CLSM) and quantified using specific parameters. While current study results agree regarding parameter tendency, there are considerable differences in terms of absolute values. The present study set out to identify factors that might account for this high parameter variability.Materials and methods: In three healthy subjects, we used a novel method of software-based large-scale reconstruction that provided SNP images of the central cornea, decomposed the image areas into all possible image sections corresponding to the size of a single conventional CLSM image (0.16 mm2), and calculated a set of parameters for each image section. In order to carry out a large number of virtual examinations within the reconstructed image areas, an extensive simulation procedure (10,000 runs per image) was implemented.Results: The three analyzed images ranged in size from 3.75 mm2 to 4.27 mm2. The spatial configuration of the subbasal nerve fiber networks varied greatly across the cornea and thus caused heavily location-dependent results as well as wide value ranges for the parameters assessed. Distributions of SNP parameter values varied greatly between the three images and showed significant differences between all images for every parameter calculated (p < 0.001 in each case).Conclusions: The relatively small size of the conventionally evaluated SNP area is a contributory factor in high SNP parameter variability. Averaging of parameter values based on multiple CLSM frames does not necessarily result in good approximations of the respective reference values of the whole image area. This illustrates the potential for examiner bias when selecting SNP images in the central corneal area.

Corneal Involvement in Uneventful Cataract Surgery: An in vivo Confocal Microscopy Study

Purpose: To evaluate corneal subbasal layer changes after uneventful cataract surgery by means of in vivo confocal microscopy. Methods: This prospective study included 30 patients. Before surgery, and 1, 3, 6, 8 and 10 months after cataract surgery, all patients underwent a complete ophthalmological and confocal microscopy examination in the central and temporal corneal areas. Number of fibers, beading, tortuosity and reflectivity were analyzed. Results: Important changes were shown in the central cornea up to 3 months after surgery: a reduction in nerve fiber number (baseline: 4.4 ± 1.7; month 1: 1.2 ± 0.5, p < 0.0001; month 3: 2.5 ± 1.2, p < 0.005) and reflectivity (baseline: 3.6 ± 0.5; month 1: 1.4 ± 0.6, p < 0.0001; month 3: 1.9 ± 0.9, p < 0. 0001), and an increase in beading (baseline: 0.3 ± 0.5 beads/100 µm²; month 1: 2.7 ± 0.6 beads/100 µm², p < 0.0001; month 3: 2.6 ± 0.5 beads/100 µm², p < 0. 0001). The confocal parameters completely progressively recovered thereafter (60% at 6 months, 87% at 8 and 10 months). The temporal plexus was absent at 1 month and fully recovered in all patients at month 8. Conclusion: Uneventful cataract surgery induces relevant corneal modifications when inspected by means of confocal microscopy.

Effect of ethanol-treated mid-peripheral epithelium on corneal wound healing in rabbits

BackgroundTo determine the effect of an ethanol-treated mid-peripheral epithelium on wound healing of the corneal epithelium.MethodsEpithelial removal was performed on 18 rabbit eyes, which were divided into three groups of six eyes each as follows: group 1, an 8.0-mm diameter treated with balanced salt solution (BSS) and an 8.0-mm removal; group 2, an 8.0-mm diameter treated with 20% ethanol for 30 seconds and an 8.0-mm removal; and group 3, a 9.0-mm diameter treated with ethanol and an 8.0-mm removal (barrier zone setting group). The corneal defect area was analyzed post-operatively. The concentrations of vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) in tears were determined pre-operatively and post-operatively. Healed corneal tissues were examined with light and electron microscopy. Immunohistochemical analysis was also performed to estimate the expression of EGF receptors in healed corneal tissue.ResultsThe epithelial healing rate in group 3 was faster than that in the two other groups (p < 0.05). The expression of VEGF and EGF in group 3 was higher than that in the other two groups (p < 0.05). Light microscopy revealed clear healing of the corneal epithelium in all groups except for some cases in group 1. Electron microscopy revealed a relatively intact microstructure of the healed corneal tissues, especially in group 2 and 3 when compared with group 1. Meanwhile, in the immunohistochemistry, group 3 showed significantly higher expression of EGFR when compared with the other groups. Furthermore, EGFR expression had a tendency to be stronger in the mid-peripheral corneal area than in the central corneal area.ConclusionsThe preserved mid-peripheral epithelial layer treated with ethanol (barrier zone) promoted corneal epithelial healing. It appeared to be correlated with elevated tear VEGF and EGF levels in the post-operative period.

Corneal displacement during tonometry with a noncontact tonometer

To measure the extent of corneal displacement during the early phase of tonometry using a noncontact tonometer and to determine the factors that affect the extent of the displacement. The cornea was photographed in profile by use of a high-speed camera during tonometry with a noncontact tonometer. The frame rate of the camera was 5,000 frames/s. The extent of the displacement of the central corneal area at 13.2 ms after application of the air puff was measured in 115 healthy volunteers. The factors that affected the extent of the corneal displacement were determined by stepwise multiple linear regression analysis. The subjects' age, sex, intraocular pressure (IOP), central corneal thickness, anterior chamber depth, and axial length were selected by the stepwise method. The results of the multiple linear regression analysis showed that subjects with low IOP, of older age, and of male sex had significantly greater displacement of the central cornea. High-speed photography can be used to evaluate the degree of corneal displacement during tonometry with a noncontact tonometer. The amount of corneal displacement is affected by the individual's IOP, age, and sex.

Spherical Aberrations of Human Astigmatic Corneas

To evaluate whether the average spherical aberration of human astigmatic corneas is statistically equivalent to human nonastigmatic corneas. Spherical aberrations of 445 astigmatic corneas prior to laser vision correction were retrospectively investigated to determine Zernike coefficients for central corneal areas 6 mm in diameter using CTView (Sarver and Associates). Data were divided into groups according to cylinder power (0.01 to 0.25 diopters [D], 0.26 to 0.75 D, 0.76 to 1.06 D, 1.07 to 1.53 D, 1.54 to 2.00 D, and >2.00 D) and according to age by decade. Spherical aberrations were correlated with age and astigmatic power among groups and the entire population. Statistical analyses were conducted, and P<.05 was considered statistically significant. Mean patient age was 42.6±11 years. Astigmatic corneas had an average astigmatic power of 0.78±0.58 D and mean spherical aberration was 0.25±0.13 μm for the entire population and approximately the same (0.27 μm) for individual groups, ranging from 0.23 to 0.29 μm (P>.05 for all tested groups). Mean spherical aberration of astigmatic corneas was not correlated significantly with cylinder power or age (P>.05). Spherical aberrations are similar to those of nonastigmatic corneas, permitting the use of these additional data in the design of aspheric toric intra-ocular lenses.

A Case of Candida Parapsilosis Keratitis With Atypical Presentation

Purpose: To report a case of Candida parapsilosis keratitis with atypical presentation demonstrated by subepithelial white dot deposits without peripheral inflammatory reaction. Case summary: A 45-year-old woman with Stevens-Johnson syndrome had used topical corticosteroid and bandage contact lens due to recurrent epithelial defect and keratitis. Multiple subepithelial white dot deposits were revealed on the central corneal area without surrounding inflammation. The corneal lesion was improved after epithelial debridement with topical antibiotics and steroid eyedrops. A few months later, however, the corneal lesion recurred. Smear cytology was performed, and yeast-formed fungi and pseudohyphae were found. C. parapsilosis was identified in the culture study. Therefore, the topical steroid was withdrawn and 0.15% topical Amphotericin was applied. The corneal lesion improved and corneal opacity did not progress. Conclusions: The case reported in this study is C. parapsilosis keratitis with multiple subepithelial white dot deposits without typical presentations of fungal kertitis. Although no typical infectious indication was evident, infection should be suspected in patients who show abnormal corneal lesion under immunosuppressive treatment.