Significant Difference In Corneal Thickness Research Articles

Enhancing Rose Bengal penetration in ex vivo human corneas using iontophoresis.

Aim: Rose Bengal photodynamic antimicrobial therapy (RB-PDAT) has poor corneal penetration, limiting its efficacy against acanthamoeba keratitis (AK). Iontophoresis enhances corneal permeation of charged molecules, piquing interest in its effects on RB in ex vivo human corneas.Methods: Five donor whole globes each underwent iontophoresis with RB, soaking in RB, or were soaked in normal saline (controls). RB penetration and corneal thickness was assessed using confocal microscopy.Results: Iontophoresis increased RB penetration compared with soaking (177±9.5μm vs. 100±5.7μm, p<0.001), with no significant differences in corneal thickness between groups (460±87μm vs. 407±69μm, p=0.432).Conclusion: Iontophoresis significantly improves RB penetration and its use in PDAT could offer a novel therapy for acanthamoeba keratitis. Further studies are needed to validate clinical efficacy.

Development and characterization of a chronic high intraocular pressure model in New Zealand white rabbits for glaucoma research

Glaucoma is a neurodegenerative disease characterized by visual field loss associated with optic nerve damage and ocular hypertension. The biological basis for the elevated intraocular pressure (IOP) is largely unknown, such that lowering the IOP is currently the only established treatment. Several animal models have been developed to elucidate the mechanism underlying the increased IOP and for use in drug discovery research, but their utility is often limited by the occurrence of severe intraocular inflammation and by technical challenges. In this study, we developed a rabbit glaucoma model that does not require experimental disease induction. Rabbits were chosen as the model because their eyeballs are similar in size to those of humans, and they are easy to breed.By crossing rabbit strains with inherited glaucoma, as indicated by obvious buphthalmos, we produced a strain that exhibits ocular hypertension. The IOP of the Ocular Hypertension (OH) rabbits was significantly higher than that of the wild type (WT; normal New Zealand white rabbits) from the age of 3 weeks to at least 22 weeks. The significantly larger corneal diameter of the OH rabbits indicated ocular enlargement, whereas there was no significant difference in corneal thickness compared with WT rabbits. Anterior segment ocular coherence tomography and gonioscopic observations revealed an open angle in the OH rabbits. Hematoxylin and eosin (HE) staining together with Masson's trichrome staining showed abnormal collagen accumulation in the angle of the OH rabbit's eyes. Furthermore, aqueous humor (AH) outflow imaging following an intravitreal injection of a fluorescent probe into the anterior chamber for tissue-section analysis revealed retention of the probe in the area of collagen deposition in the OH eyes. The OH rabbits also had a time-dependent increase in the cup/disc ratio.In conclusion, investigations using our newly developed rabbit model of open-angle ocular hypertension showed that abnormal accumulation of extracellular matrix at the angle increased AH outflow resistance in the conventional outflow pathway, leading to a high IOP. Furthermore, the OH rabbits exhibited glaucomatous optic disc cupping over time. These findings suggest the utility of the OH rabbits as a model for open-angle glaucoma (OAG).

Ocular Surface Characteristics in Pugs with Pigmentary Keratitis in the Canary Islands, Spain.

This study investigated the prevalence of pigmentary keratitis (PK) in Pug-breed dogs and described the ocular surface characteristics associated with this disease. A total of 219 eyes from 110 dogs were examined, with 94.5% of them affected by PK. Age, previous ocular diseases, corneal vascularization, and corneal sensitivity were significantly associated with the presence of PF and the severity of corneal pigmentation. The study also found that low tear production and blinks incomplete with tear signs, as well as reduced corneal sensitivity, were linked to more severe forms of corneal pigmentation. The Tear Ferning Test (TFT) was identified as a valuable tool for evaluating tear quality in dogs, with worse test results indicating a higher risk of severe PK. A lower mean Tear Break-Up Time (TBUT) test was observed in dogs with PK. Additionally, the study observed a statistically significant difference in corneal thickness between the nasal and temporal zones, with the nasal zone being thicker. It was also suggested that sex and fertility status may influence the incidence of PK and the severity of corneal pigmentation. Overall, these findings provide insight into the underlying causes of PK in Pugs and can inform future treatment strategies for this breed.

Comparative study of the central corneal thickness in healthy individuals and diabetic patients with and without retinopathy using anterior segment optical coherence tomography

Abstract Background Chronic hyperglycemia in diabetes mellitus causes different morphologic and functional corneal changes. Aim of the Work to assess the central corneal thickness in diabetic patients with and without diabetic retinopathy using anterior segment optical coherence tomography. Patients and Methods This comparative study was conducted at Ain Shams University hospitals . It included 45 eyes divided into three groups: Group A: 15 eyes of diabetic patients without diabetic retinopathy , Group B: 15 eyes of diabetic patients with diabetic retinopathy and Group C: 15 eyes of non-diabetic individuals. Results : The mean CCT in diabetic patients without diabetic retinopathy was 551.13µ ± 37.93 with range 475-622. Diabetics with retinopathy was 558.93µ ± 39.32 with range 508-618 and non diabetics 534.73µ ± 33.67 with range 475-588. There was no significant difference in corneal thickness between the three groups (p = 0.201) Conclusion : Diabetic corneas tended to be thicker though this was not statistically significant in our work.

Evaluation of changes in corneal endothelial morphology during the progression of pterygium by specular microscopy

Background/Aim: Corneal endothelial morphology may be corrupted due to pterygium progression. To the best of our knowledge, no study in the literature investigates this. We aimed to evaluate corneal endothelial morphology using specular microscopy (SM) in patients with pterygium. Methods: In this case-control study, we included thirty-three Type 1 pterygium, thirty-one Type 2 pterygium, thirty Type 3 pterygium patients, and thirty healthy controls. The corneal endothelia of all patients were evaluated by SM, and cell density (CD), hexagonal cell ratio (HEX), corneal thickness (CT), and coefficient of variation (CV) were noted. Results: While there was no significant difference in corneal thickness (P=0.480) and coefficient of variation (P=0.068) between the groups in SM images, both corneal endothelial cell count (P=0.003) and hexagonal cell ratio (P=0.002) were significantly lower in Type 2 and Type 3 pterygium patients compared to Type 1 and control groups. Discussion: Corneal endothelial morphology was severely affected in type 2 and 3 pterygium. We think that type 2 and type 3 pterygium patients should be operated on as soon as they are diagnosed to prevent deterioration in corneal endothelial parameters.

Inducible Slc4a11 Knockout Triggers Corneal Edema Through Perturbation of Corneal Endothelial Pump.

PurposeThe conventional Slc4a11 knockout (KO) shows significant corneal edema at eye opening, a fact that complicates the study of the initial events leading to edema. An inducible KO would provide opportunities to examine early events following loss of Slc4a11 activity.Methods Slc4a11 Flox (SF) mice were crossed with mice expressing the estrogen receptor Cre Recombinase fusion protein and fed tamoxifen (Tm) for two weeks. Corneal thickness (CT) was measured by OCT. At eight weeks endpoint, oxidative damage, tight junction integrity, stromal lactate concentration, endothelial permeability, differentially expressed transporters, and junction proteins were determined. Separately, a keratocyte only inducible Slc4a11 KO was also examined.ResultsAt four weeks post-Tm induction Slc4a11 transcript levels were 2% of control. Corneal thickness increased gradually and was 50% greater than Wild Type (WT) after eight weeks with significantly altered endothelial morphology, increased nitrotyrosine staining, significantly higher stromal lactate, decreased expression of lactate transporters and Na-K ATPase activity, higher ATP, altered expression of tight and adherens junctions, and increased fluorescein permeability. No significant differences in CT were found between WT and keratocyte only Slc4a11 KO.ConclusionsThe Slc4a11 inducible KO shows development of a similar phenotype as the conventional KO, thereby validating the model and providing a tool for further use in examining the sequence of cellular events by use of noninvasive in vivo physiological probes.

Effect of treatment with silver(I) complex of metronidazole on ocular rosacea: Design and formulation of new silver drug with potent antimicrobial activity

BackgroundMetronidazole with well-soluble silver nitrate forms a complex with potent activity (synergism) against bacterial strains and fungi with simultaneous lower side effect than in the case of the two agents administered separately.This study aimed to establish effectiveness in the treatment of ocular rosacea with new formulation of drops and ointment with silver(I) complex of metronidazole. MethodsThree patients suffering from serious ophthalmic complications of acne rosacea were treated with drops and ointments applied 3 times a day for 3 months. The uncorrected visual acuity testing (UCVA), pachymetry as well as subjective and objective tear film assessment were evaluated. ResultsIn all patients, we have improved UCVA as well as objective and subjective evaluation of the tear film parameters. No significant differences in corneal thickness were observed. ConclusionWell soluble silver(I) complex of metronidazole might be an alternative method in ophthalmic complications of acne rosacea treatment.

Assessment of Corneal Endothelium among Diabetic Patients in a Multispecialty Hospital in Tamil Nadu

Introduction: Corneal damage is the common issue affecting 70% of diabetic patients. Diabetic cornea has functional abnormalities such as decreased corneal Endothelial Cell Density (ECD), thicker corneas with increased endothelial permeability, lesser corneal sensitivity, and elevated corneal auto-fluorescence. Aim: To study the corneal endothelial characteristics among diabetic patients and to identify the factors associated with endothelial damage and compare the corneal changes based on the duration of diabetes mellitus and glycaemic control. Materials and Methods: The hospital based cross-sectional study was conducted in 155 patients (100 diabetic and 55 control) from 24th September 2016 to 29th March 2018. The corneal endothelial morphological features were evaluated using a non-contact EM-3000 specular microscope. The morphological characteristics of endothelial cell like the ECD, Coefficient of Variation (CV), Central Corneal Thickness (CCT), and percentage of hexagonal cells were compared between diabetic patients and the control population. Age, gender, blood pressure, duration of diabetes, fasting and Postprandial Blood Sugar (PPBS) HbA1c value, blood urea, and serum creatinine, Intra Ocular Pressure (IOP) were also recorded, and the endothelial cell characteristics were compared between the diabetic groups according to the duration (&lt; or ≥ 3 years) and HbA1c% (&lt; or ≥ 7%). An independent t-test was performed to compare the means of endothelial characteristics between study subjects and the control group and also between duration of diabetes and HbA1C levels. A p-value of less than 0.05 was considered statistically significant. The data were analysed using a SPSS statistical program. Results: Baseline characteristics like Fasting Blood Sugar (FBS), PPBS, HbA1c, Systolic and Diastolic Blood Pressure (SBP and DBP) were significantly higher in diabetic group than control. A significant difference in corneal thickness (p=0.01) and hexagonality (p&lt;0.001) were also observed between both the groups. The diabetic group showed a reduction in cell density and a higher coefficient variation of cell size however the differences were not statistically significant, There was no significant difference in the ECD, CCT, CV, and hexagonality irrespective to HbA1c level and duration of diabetes. Conclusion: Patients with diabetes had a significant increase in corneal thickness, and a higher frequency of pleomorphism compared to control subjects. In terms of ECD and co-efficient variation, no difference was observed between groups.

Changes in corneal thickness in patients with high-altitude pulmonary edema after systemic oxygen therapy.

Purpose:High-altitude pulmonary edema (HAPO) is an acute medical emergency occurring typically in lowlanders, who ascend rapidly to heights of 3000 m or more. It presents with marked dyspnea on exertion, fatigue with minimal-to-moderate effort, prolonged recovery time, and dry cough with manifestations of cyanosis, tachycardia, tachypnea, and temperature which generally does not increase beyond 38.5°C. The condition may be fatal if not treated in time with supplemental oxygen or hyperbaric oxygen or rapid descent to lower altitude. There is paucity in literature on changes in corneal thickness in HAPO. The effect of continued oxygen therapy on corneal thickness has also not been studied in detail. Hence, this study was conducted at high altitude among physician-confirmed HAPO cases.Methods:A case–control study was conducted at an altitude of 11,400 feet. Cases were patients suffering from HAPO and controls were patients admitted in hospital for low back pain, fractures, and minor surgical procedures. Central corneal thickness (CCT) was measured with an ultrasound pachymeter on day 1 of hospitalization and every day of hospital stay. Systemic oxygen concentration was also measured daily.Results:There was no statistically significant difference in corneal thickness between two groups at the onset of illness, but a significant decrease in CCT was found in both right and left eyes in HAPO cases when oxygen levels were increased by giving supplemental oxygen. Hierarchical modeling showed a decrease in 1.3 μm in CCT with one unit increase in oxygen mmHg in cases.Conclusion:The findings of statistically insignificant difference in CCT between HAPO cases and controls and a decrease in CCT in HAPO cases on being treated with systemic oxygenation are points to ponder about.

Ocular dimensions, corneal thickness, and corneal curvature in quarter horses with hereditary equine regional dermal asthenia.

The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses. Five HERDA-affected quarter horses and five healthy control quarter horses were used. Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound scanning was performed on both eyes of each horse to determine the dimensions of the ocular structures and to calculate the corneal curvature. Each corneal region examined in this study was thinner in the affected group compared with the healthy control group. However, significant differences in corneal thickness were only observed for the central and dorsal regions. HERDA-affected horses exhibited significant increases in corneal curvature and corneal diameter compared with unaffected animals. The ophthalmologic examinations revealed mild corneal opacity in one eye of one affected horse and in both eyes of three affected horses. No significant between-group differences were observed for Schirmer's tear test, intraocular pressure, or ocular dimensions. Hereditary equine regional dermal asthenia-affected horses exhibit decreased corneal thickness in several regions of the cornea, increased corneal curvature, increased corneal diameter, and mild corneal opacity. Additional research is required to determine whether the increased corneal curvature significantly impacts the visual accuracy of horses with HERDA.

Fourier-domain optical coherence tomography evaluation of clear corneal incision structure according to blade material

To use Fourier-domain optical coherence tomography (OCT) to evaluate the wound characteristics of clear corneal incisions (CCIs) created with a metal or diamond blade in cataract surgery. Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea. Prospective comparative observational study. Patients who had cataract surgery were randomized into 2 groups based on whether a metal blade (Group 1, 37 eyes) or diamond blade (Group 2, 33 eyes) was used to create a 2.8 mm temporal CCI. One day, 1 week, and 1 month postoperatively, structural characteristics of the CCI were analyzed using RTVue-100 Fourier-domain OCT. Parameters included incision angle, corneal thickness, epithelial or endothelial gaps, and Descemet membrane detachment. Visual acuity, surgically induced astigmatism (SIA), and ocular aberrations were evaluated. There was a significant difference in corneal thickness at the 1.0 mm temporal side from midpoint. The mean uncorrected distance visual acuity in Group 2 (33 eyes) improved significantly over time. In both groups, corneal thickness at the midpoint, 1.0 mm temporal side, and 1.0 mm nasal side from the midpoint of the incision significantly decreased over time. At all timepoints, temporal and nasal thickness in Group 2 was significantly greater than in Group 1 (37 eyes), with the exception of temporal thickness at 1 month. In both groups, wound healing was reliable over time. There were no significant between-group differences in SIA or changes in aberrations. Corneal thickness at the incision site showed a significant difference between the 2 groups. Both groups achieved structural stabilization. No author has a financial or proprietary interest in any material or method mentioned.

Phacopower Modulation and the Risk for Postoperative Corneal Decompensation

In compromised corneas, eg, patients with Fuchs endothelial dystrophy (FED), it is of utmost importance to use a phacotechnique that is the least traumatic to the corneal endothelium. Furthermore, preoperative patient selection is crucial, because unexpected corneal decompensation leads to dissatisfied patients. To compare corneal thickness and corneal volume changes using torsional and longitudinal phacoemulsification in patients with Fuchs endothelial dystrophy (FED) and determine risk factors of postoperative corneal decompensation. Prospective randomized clinical trial of all patients diagnosed with FED and planning to undergo cataract surgery for visually significant cataract at a university medical center from November 2008 to May 2010. Fifty-two eyes with FED and visually significant cataract underwent torsional (n = 26) or longitudinal (n = 26) phacoemulsification. Patients were evaluated preoperatively and 1 day, 1 week, 1 month, 3 months, and 6 months postoperatively. Visits included best spectacle-corrected visual acuity, anterior segment optical coherence tomography evaluating central corneal thickness (CCT) and peripheral corneal thickness (PCT), and Scheimpflug imaging calculating corneal volume (CV). Randomization took place according to stage of FED, nucleus density grade, and age. Intraoperatively, ultrasonography time and cumulative dissipated energy were recorded. Central corneal thickness, PCT, and CV. Ultrasonography time and cumulative dissipated energy were significantly lower in the torsional group for harder nucleus density grades compared with the longitudinal group (P = .009 and P = .002, respectively). Peripheral corneal thickness at the 6-o'clock position, CCT, and CV were significantly smaller in the torsional group 1 day postoperatively (P = .002; P = .03; and P = .004, respectively). Changes in PCT at the 12-o'clock position and best spectacle-corrected visual acuity were not significantly different between the 2 groups (P > .05). Preoperative CCT was the only significant predictor of corneal decompensation postoperatively (P < .001). Preoperative CCT of 620 µm corresponded to an odds ratio of 1, meaning no increased risk of developing corneal decompensation. For each 10-µm increase in preoperative CCT, the odds of developing corneal decompensation increased 1.7 times. Torsional phacoemulsification effectively reduces ultrasonography time and cumulative dissipated energy compared with longitudinal phacoemulsification in patients with FED. However, there were only significant differences in corneal thickness and CV changes at 1 day postoperatively in favor of the torsional group. Central corneal thickness more than 620 µm, measured by noncontact pachymetry, leads to an increased risk for corneal decompensation after phacoemulsification in patients with FED. clinicaltrials.gov Identifier: NCT00781027.

Comment on ‘Corneal hysteresis in patients with dry eye’

Sir, We read with interest Firat and Doganay's1 recent report on effects of dry eye on corneal biomechanics. We propose the authors missed the opportunity to review an interesting hypothesis because of inadequate study design and methodology. Whereas the report aimed to determine effects of dry eye, the disease classification and study enrolment criteria were poorly defined. We would like to bring to the authors attention the International Dry Eye Workshop report (2006) that provides a standardized classification for diagnosis and grading severity of dry eye.2 Including patients with significant ocular surface disorders may have allowed accurate conclusions. The absence of significant difference in corneal thickness probably reflects milder disease in the study group.3 Goldman applanation tonometry (GAT) is based on assumptions of the tear film and known to be affected by the central corneal thickness. The Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Buffalo, NY, USA) is a non contact tonometer that measures the biphasic corneal response to generate a cornea compensated intraocular pressure (IOPcc). The more interventional contact GAT measurements were surprisingly recorded earlier in the sequence of measurements. Data for analysis and comparison of IOP between the two instruments or even the Goldmann-correlated IOP measurement, IOPG (average of the biphasic pressure readings generated by the ORA) vs IOPCC, are not provided. The results are duplicated in text and bar chart format, as opposed to use of a scatter plot with range of measurements and do not contribute to the discussion. The authors' hypothesis on effect of dry eye in IOP measurements (traditional and newer cornea compensated values) and corneal biomechanics can have important clinical implications. However, the lack of definition and severity grading of dry eye makes it difficult to draw accurate conclusions.

Wound Architecture of Clear Corneal Incision With or Without Stromal Hydration Observed With 3-Dimensional Optical Coherence Tomography

To evaluate wound architectures of a clear corneal incision and the duration of stromal edema caused by intentional hydration in cataract surgery using 3-dimensional (3-D) cornea and anterior segment optical coherence tomography (OCT). Prospective, randomized study. On 30 eyes of 23 patients, cataract surgery was performed through a clear corneal incision created with a 2.4-mm blade. After confirming the water tightness of the clear corneal incision at the end of surgery, 15 randomly selected eyes received stromal hydration, and the remaining 15 eyes did not. Using the 3-D cornea and anterior segment optical coherence tomography, wound architecture was assessed 1 day, 1 week, and 2 weeks after surgery. There was a statistically significant difference in corneal thickness at the clear corneal incision between eyes with and without stromal hydration 1 day and 1 week after surgery (P < .001 and P < .05, Mann-Whitney U test), but not at 2 weeks after surgery. On day 1, gaping at the epithelial side was seen in 6.7% (2 eyes), gaping at the endothelial side in 30% (9 eyes), misalignment of the roof and floor of incision in 40% (12 eyes), and local detachment of Descemet membrane in 36.7% (11 eyes). These imperfections improved with time. Using the 3-D cornea and anterior segment optical coherence tomography, detailed architectures of the clear corneal incision were investigated. It was found that the effect of stromal hydration lasted for at least 1 week after surgery.

Knockdown of NBCe1 In Vivo Compromises the Corneal Endothelial Pump

To evaluate the role of the sodium bicarbonate cotransporter (NBCe1) as a component of the corneal endothelial pump in the in vivo rabbit eye. Lentiviruses with NBCe1 shRNA and GFP expression cassettes were injected intracamerally. Knockdown efficacy was determined 1 week to 4 weeks later by immunofluorescence, Western blot analysis, and PCR. Functional effects were monitored by corneal thickness (CT) and brinzolamide sensitivity. Within 24 hours there was a modest anterior chamber inflammation that resolved within 48 hours. At 4 × 10(6) IFU, more than 95% of the corneal endothelial surface showed GFP fluorescence above background within 7 days. At 14 to 21 days, signs of anterior chamber inflammation reemerged, and endothelial cell GFP fluorescence disappeared within 40 days after injection. The second phase of inflammation could be avoided by using GFP-less viruses. There was no significant difference in CT between scrambled sequence and NBCe1 shRNA-injected eyes over 3 weeks. Two drops of 1% brinzolamide produced 7.85% ± 3.3% corneal swelling within 5 hours of topical instillation. However, in corneas showing more than 25% NBCe1 knockdown (30 of 42 rabbits; 59% ± 15% knockdown), corneal swelling was significantly higher (10.1% ± 2.9%) relative to control eyes. FIV-based lentiviral vectors can transfect CE with shRNA in rabbits. The response to GFP is consistent, with previous studies showing the production of anti-GFP antibodies. Partial knockdown of NBCe1 did not affect baseline CT, which is consistent with the corneal endothelium having a substantial functional reserve. Provocative testing using, brinzolamide, however, revealed an underlying deficiency, confirming the importance of NBCe1 bicarbonate transport and demonstrating the concerted action between NBCe1 and carbonic anhydrases.

Central Corneal Thickness in Tilted Disc Syndrome

: Earlier literature reports that abnormal optic disc shape or size seem to be closely associated with the shape or size of the cornea. Here we search for an association between the presence of tilted disc syndrome and the central corneal thickness. : Sixty-one eyes of 61 patients with tilted disc syndrome were included in the study. Sixty-one eyes of 61 subjects were chosen as controls. Corneal thickness was evaluated with ultrasound pachymetry from the central region after instillation of topical proparacaine hydrochloride and before the ophthalmologic examination. : The mean central corneal thickness in the tilted disc syndrome group was found to be 547.5 +/- 36.16 mum (median 546, range 467 to 638). The mean central corneal thickness in the control group was measured as 541.09 +/- 29.52 mum (median 540, range 500 to 627). There was no statistically significant difference in corneal thickness between the tilted disc syndrome group and control group (p = 0.218). : There seems to be no correlation between the central corneal thickness and the presence of tilted disc syndrome.

Necessary Prone Position Time for Human Corneal Endothelial Precursor Transplantation in a Rabbit Endothelial Deficiency Model

Purpose: We previously performed human corneal endothelial precursor cell transplantation into the anterior chamber and maintenance of the prone position for 24 hours in a bullous keratopathy model. This time, we investigated the necessary postoperative time in the prone position for clinical application of precursor cell transplantation. Methods: The sphere-forming assay was used to obtain precursors from cultured human corneal endothelial cells. Chloromethyl benzamidodialkylcarbocyanine (CM-DiI)-labeled precursor cells were injected into the anterior chamber of the eye in rabbits with corneal endothelial defects, and the prone position was maintained for 0, 1, 6, or 24 hours to allow attachment to Descemet's membrane. Rabbits maintained in the prone position for 24 hours without precursor cell transplantation were the controls. Each group was observed for 28 days after surgery, followed by histological examination and fluorescence microscopy. Results: The mean corneal thickness of the rabbits kept in the prone position for 1, 6, or 24 hours after precursor cell transplantation was significantly less than that of the rabbits without adoption of the prone position after transplantation or the untransplanted rabbits at 14 days (p < 0.005), 21 days (p < 0.0001), and 28 days (p < 0.0001) after surgery. And there was no significant differences in corneal thickness between the two groups kept in the prone position for 6 hours and 24 hours throughout the observation DiI-positive human corneal endothelial-like hexagonal cells were detected on Descemet's membrane in the rabbits kept in the prone position for 1, 6, or 24 hours, but not in the control groups. Three of the six corneas in the 1-hour group showed focal edema and incomplete coverage of the endothelial defects. Conclusions: Our findings demonstrated that transplantation of human corneal endothelial precursors into the anterior chamber with adoption of the prone position for 6 hours treated bullous keratopathy in rabbits with similar efficacy to maintenance of the prone position for 24 hours after surgery.

Changes in the shape of the anterior and posterior corneal surfaces caused by mydriasis and miosis: Detailed analysis

Purpose: To evaluate changes in the anterior and posterior corneal shape, corneal thickness, and anterior chamber depth (ACD) caused by mydriasis or miosis using scanning-slit corneal topography. Setting: Department of Ophthalmology, Iwate Medical University School of Medicine, Iwate, Morioka, Japan. Methods: Twenty-eight eyes of 28 healthy volunteers with refractive errors of −6.00 to +0.25 diopters were studied. One eye of each subject had instillation of tropicamide–phenylephrine hydrochloride (Mydrin P®) to obtain mydriasis and of pilocarpine hydrochloride 2% (Sanpilo®) to obtain miosis. To assess the corneal shape, the best-fit sphere (BFS), axial power, and tangential power were measured for the anterior and posterior corneal surfaces before and after mydriasis and before and after miosis using scanning-slit corneal topography (Orbscan version 3.0, Orbtek, Inc.). The pupil size, corneal thickness, and ACD were also examined before and after mydriasis and before and after miosis. Results: The mean age of the patients was 31.1 years ± 5.6 (SD) (range 20 to 46 years). The anterior BFS changed from a mean of 8.04 ± 0.3 mm at the time of mydriasis to a mean of 8.00 ± 0.3 mm at the time of miosis. The posterior BFS changed from 6.53 ± 0.3 mm to 6.46 ± 0.3 mm, respectively. Thus, the anterior and posterior cornea became significantly steeper after miosis ( P<.01). The ACD was significantly more shallow after miosis than after mydriasis. However, there was no significant difference in corneal thickness after mydriasis or miosis. Conclusions: The anterior and posterior corneal shapes changed as a result of mydriasis and miosis, and the refractive power of the cornea significantly increased after miosis. To date, changes in refractive power from changes in pupil size have been attributed to a change in the refractive power of the crystalline lens; however, it is now thought that changes in corneal refractive power also occur.

Corneal thickness at different reference points from Orbscan II system

Background: To locate the thinnest region of the cornea and ascertain whether there is a mismatch between the corneal apex and the thinnest part of the cornea, both as defined by the Orbscan I1 system. Methods: Ninety‐two eyes of 46 normal subjects were investigated with three reference points identified: the fixation point, the corneal apex and the thinnest region of the cornea. These three points were predetermined by the topographic software system and categorised into different quadrants. Results: The thinnest region of the cornea was found to be located in the inferior temporal quadrant for the right eye and inferior for the left eye. There was no significant difference in corneal thickness between the thinnest region of the cornea and the corneal apex. There was a significant difference found in the location of the reference points (p < 0.01). Conclusions: Differences in the location of the reference points may be of clinical significance, however, our study showed that the corneal thickness at these reference points is not significantly different. Users of the Orbscan II system are free to use any reference points at the central region without reaching any significant difference in corneal thickness.

Randomized clinical comparison of Healon GV and Viscoat

Purpose To compare the ability of Healon GV® (sodium hyaluronate 1.4%) and Viscoat® (sodium chondroitin sulfate 4.0%–sodium hyaluronate 3.0%) to protect the corneal endothelium during endocapsular phacoemulsification and foldable intraocular lens (IOL) implantation. Setting A small ophthalmology group practice. Methods One hundred forty patients were randomized, 70 per group, in a prospective, partially masked study of cataract surgery using Healon GV or Viscoat. One ophthalmologist performed all surgery. Primary outcome variables were the 2 week postoperative changes in corneal thickness, endothelial cell density, mean endothelial cell size, and endothelial cell hexagonality. Several secondary variables were measured, and an analysis of the statistical power of the study was performed. Results There were no statistically significant differences between groups in terms of age ( P = .856), cataract density ( P = .117), preoperative best corrected visual acuity (BCVA) ( P = .892), postoperative BCVA ( P = .969), amount of viscoelastic material used during surgery ( P = .444), amount of irrigating solution used ( P = .125), or phacoemulsification time ( P = .088). It took longer to remove the Viscoat than the Healon GV ( P < .001), and total operating time for the Viscoat group was longer ( P < .001). Two weeks after surgery, there were no significant differences between groups in corneal thickness ( P = .362), endothelial cell density ( P = .351), or mean endothelial cell size ( P = .610). However, Viscoat preserved the hexagonal shape of endothelial cells slightly better than Healon GV ( P = .043). The study had sufficient power to detect clinically significant differences in corneal thickness, endothelial cell density, and endothelial cell size. Conclusions Healon GV and Viscoat were comparable in their ability to protect the corneal endothelium during endocapsular phacoemulsification and foldable IOL implantation. Results may vary, however, if phacoemulsification is performed anterior to the iris plane.