Increase In Corneal Thickness Research Articles

Evaluation of Irradiated Corneas Using Scatterometry and Light and Electron Microscopy.

To determine if sterilization of donor corneas by irradiation alters optical, histologic, or ultrastructural tissue characteristics. Blinded assessment of 10 irradiated and 10 nonirradiated donor corneas by a scatterometer used to objectively measure backscattered corneal light. Light and electron microscopy were performed on samples from both groups. The mean scattering of the nonirradiated (control) corneas was significantly lower (0.0060 ± 0.0034, mean ± SD) than the scattering of the irradiated corneas (0.023 ± 0.0078; P = 0.0001). There was no statistical difference between ages, days in storage, or central corneal thickness of the 2 groups. Light microscopic evaluation revealed attenuation of the irradiated corneal epithelium with superficial stromal clefting. Transmission electron microscopy demonstrated similar fibril diameter in the nonirradiated and irradiated corneas. Although the mean interfibrillar distance was similar between the nonirradiated and irradiated groups, the interfibrillar distance in the superficial stroma was increased in the nonirradiated compared with the irradiated groups (15.4 ± 2.4 vs. 11.8 ± 0.98 nm; P ≤ 0.05). Our data quantitatively support increased light scatter after irradiation, which cannot be attributed to increased corneal thickness. Irradiation alters the histology of the epithelium and the ultrastructure of the superficial corneal stroma. Increased light scatter because of epithelial changes would not be expected to impact postoperative visual function. However, increased light scatter because of stromal changes may affect postoperative visual function if used for optical corneal rehabilitation. Further investigation is warranted to determine whether attenuated epithelium or superficial stromal changes are the cause of increased light scatter in the irradiated corneal tissue.

Effect of a proparacaine 0.50%–sodium fluorescein 0.25% mix and contact ultrasound pachymetry on central and midperipheral corneal thickness measured by noncontact optical pachymetry

To assess the effect of a combination of proparacaine 0.50%-sodium fluorescein 0.25% and ultrasound (US) pachymetry on central and midperipheral corneal thickness. School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom. Case series. Topographic measurements of corneal thickness in healthy right eyes were obtained using a scanning-slit device (Orbscan IIz) and a Scheimpflug device (Pentacam) before and after application of proparacaine 0.50%-sodium fluorescein 0.25% and US pachymetry. Changes in corneal thickness in the center and 2.5 mm from the center in the temporal, nasal, inferior, and superior locations were assessed. The study evaluated 35 eyes. The scanning-slit and Scheimpflug devices recorded a small but statistically significant increase in corneal thickness at all locations (mean 4.9 ± 14.3 [SD] to 9.1 ± 11.7 μm; P<.05, paired t test). The cornea swelled uniformly across its diameter (scanning slit, P=.934; Scheimpflug, P=.654; analysis of variance); there was no statistically significant difference in the amount of swelling between the 2 devices (P>.05, t test). The 95% limits of agreement were broad (-10 to +30 μm), suggesting a large degree of interindividual variability. Ultrasound pachymetry combined with proparacaine 0.50%-sodium fluorescein 0.25% caused a small (<10 μm) but significant amount of corneal swelling on average. Because the effect on corneal thickness may be greater than -10 to +30 μm in individual cases, clinicians should avoid contact procedures before obtaining topographic maps of corneal thickness using scanning-slit and Scheimpflug devices.

Intraocular pressure after Descemet’s stripping and non-Descemet’s stripping automated endothelial keratoplasty

To evaluate the effect on intraocular pressure (IOP) of increased corneal thickness after Descemet's stripping automated endothelial keratoplasty (DSAEK) and of non-Descemet's stripping automated endothelial keratoplasty (nDSAEK) as measured by four different techniques. Twenty-four eyes (22 patients; mean age, 74.0 years) with successful DSAEK (11 eyes) or nDSAEK (13 eyes) treatment at least 3 months prior to testing were enrolled. IOP was measured with Goldmann applanation tonometry (GAT), dynamic contour tonometry (DCT), pneumatonometry, and Tono-Pen XL (Tonopen). Central corneal thickness (CCT) was measured by ultrasonic pachymetry. These data were used for statistical analysis. Mean IOP measured by GAT, DCT, pneumatonometry, and Tonopen was 14.4, 13.9, 11.2, and 13.2 mmHg, respectively, in the DSAEK group; and 15.0, 14.4, 12.5, and 14.4 mmHg, respectively, in the nDSAEK group. Correlations between IOP and CCT were not statistically significant in either group. Pressure measured by pneumatonometry was significantly and consistently lower than that obtained by the other three methods. For both DSAEK and nDSAEK, IOP readings by the four tonometers seem to be unrelated to artificially thickened corneas.

In Vivo Analysis of Stromal Integration of Multilayer Amniotic Membrane Transplantation in Corneal Ulcers

To evaluate integration of amniotic membrane into the corneal stroma using laser scanning in vivo confocal microscopy and anterior segment optical coherence tomography (AS-OCT). Prospective noncomparative interventional case series. Twenty-two eyes of 22 consecutive patients (mean age 53.9 ± 9.2 years) presenting with noninfectious corneal ulcers and stromal thinning unresponsive to medical treatment were enrolled. Multiple layers of amniotic membrane were applied over the ulcer bed to fill the ulcer crater and held in place with an overlying amniotic membrane patch, which was anchored to the surrounding cornea with 10-0 nylon interrupted sutures. Outcome measures were healing of the corneal ulcers, corneal morphology and stromal thickness changes at the ulcer site as measured by AS-OCT and surface epithelialization, stromal repopulation, and structural modifications of the amniotic membrane grafts as evaluated by confocal microscopy. Follow-up extended to 12 months. Successful result was observed in 20 of 22 eyes (90.9%). AS-OCT showed that the mean residual stromal thickness at the ulcer bed was 222 ± 70 μm before surgery. The mean thickness of amniotic membrane layers at the same site was 394 ± 80 μm while the mean total corneal thickness was 623 ± 51 μm at day 1 post surgery. Thereafter a progressive reduction in thickness to 420 ± 61 μm at 6 months occurred, after which the thickness stabilized. Confocal microscopy showed that integration of the amniotic membrane tissues with corneal stroma was preceded by epithelialization over the amniotic membrane covering the ulcer. This occurred 15 ± 5 days post surgery in the successful cases. Confocal microscopy also showed that the amniotic membrane patch was degraded during the first few weeks after surgery, while the integrated amniotic tissues underwent progressive modifications characterized by early loss of amniotic epithelial cells, changes in fibrillar structure, and migration into the amniotic stroma by corneal stroma-derived cells. Multiple layers of amniotic membrane can integrate into the corneal stroma with resulting increase in corneal thickness. This appears to be related to re-epithelialization of the transplanted membrane. Integrated amnion within the stromal defect undergoes progressive changes including contraction of tissue and repopulation by corneal stroma-derived cells.

Microcoaxial Torsional Cataract Surgery 1.8 mm Versus 2.2 mm: Functional and Morphological Assessment

To compare functional and morphological outcomes of 1.8-mm versus 2.2-mm microincision coaxial cataract surgery (MCCS). Thirty eyes of 30 patients that underwent MCCS were randomized to two groups: 1.8-mm MCCS (group 1: 15 eyes) and 2.2-mm MCCS (group 2: 15 eyes). There were no significant between-group differences in uncorrected visual acuity, best-corrected visual acuity, keratometric astigmatism, and endothelial cell count. One day postoperatively, a greater increase of corneal thickness at the incision site was observed in group 1 compared to group 2 using anterior segment optical coherence tomography with no significant differences in tunnel morphometric features and confocal microscopy showed more tunnel edema in group 1 versus group 2 that resolved in both groups. Both 1.8- and 2.2-mm torsional MCCS were safe and efficient with easy surgical maneuvers and excellent functional and morphological results; 1.8-mm MCCS induced slightly greater tunnel edema shortly after surgery that resolved in the medium term.

Acquired Central Corneal Thickness Increase Following Removal of Childhood Cataracts

To evaluate central corneal thickness (CCT) in children with congenital/developmental cataracts before and after cataract removal, to correlate CCT with corneal diameters before cataract surgery in this same group, and to evaluate CCT over time in a separate group of children who were already aphakic or pseudophakic at study entry. Longitudinal study. Children with cataract (Group 1, with pre-cataract-removal CCT) and aphakia/pseudophakia (Group 2, presenting after cataract removal) were included. CCT measurements were performed using ultrasound pachymetry. Normal fellow eyes of unilaterally affected cases served as controls. In bilateral cases, right eyes were used for analyses. Group 1 comprised 66 children. Before cataract surgery, unilateral cases (n = 31) showed similar CCT and strong association between the affected and fellow eyes (552.0 ± 32.9 μm vs 550.9 ± 40.4 μm, respectively; r(2) = 0.71, P = .0001). After cataract surgery, affected eyes (n = 13) showed mean CCT increase of 29.7 ± 43.1 μm (P = .03) while fellow eyes remained unchanged. Similarly, before cataract surgery, bilateral cases (n = 35) showed similar CCT between the right and left eyes. After cataract surgery, mean CCT increase was 27.4 ± 39.4 μm for first operated eyes of bilateral cases (n = 17, P = .01). Group 2 comprised 50 aphakic/pseudophakic children lacking pre-cataract-removal CCT. CCT was higher in eyes with glaucoma vs those without, at both first and last measurements (ΔCCT 58.9 ± 27.0 μm at first examination, P = .034, and 56.4 ± 27.1 μm at last examination, P = .043, respectively). There was no statistically significant CCT change over the study interval (median 28 months) for either Group 2 eyes with or those without glaucoma. CCT in children with cataracts increases after cataract surgery while the fellow eye remains stable. This increase seems to occur early after surgery, likely remaining stable thereafter, though glaucoma can accentuate the increase.

The effect of C3F8 gas on corneal endothelial cells in rabbits

To evaluate the ocular effects of perfluoropropane gas (C(3)F(8)) in the anterior chamber of rabbit eyes in relation to the gas concentration. Twenty rabbit eyes were randomly divided into four groups (20%, 15%, and 10% C(3)F(8) gas groups, and an air control group). After injection of 0.3 ml of each gas concentration into the anterior chamber, endothelial damage was evaluated by specular microscopic analysis. The main outcome measurements were endothelial cell density, hexagonality, coefficient of variation, corneal thickness, and intraocular pressure (IOP) 1 day, 1 week, and 2 weeks after injection. Two weeks after injection, transmission electronic microscopy was performed to evaluate the structural integrity. The 20% group had a significant decrease in endothelial cell density (P = 0.023), hexagonality (P = 0.031), and increase in corneal thickness (P = 0.045) from baseline to 2 weeks after injection, whereas the other groups exhibited no significant differences. The 20% group had a significant increase in IOP 1 week after injection (P = 0.041). Transmission electron microscopy revealed that the 20% group had a severe flat cell configuration with a damaged intracellular organization. The risk of endothelial cell damage and elevation in IOP was greater in the 20% C(3)F(8) group than in the 15% or 10% C(3)F(8) groups. Therefore, an appropriate concentration of C(3)F(8) gas is needed for different surgical purposes.

Pathologic epithelial and anterior corneal nerve morphology in congenital aniridic keratopathy

Abstract Purpose To document corneal morphology in Swedish families with congenital aniridia. Methods Detailed ophthalmic examinations were conducted in a number of affected and unaffected members. Digital slit lamp photography, anterior segment optical coherence tomography (ASOCT) and in‐vivo confocal microscopy (IVCM) examinations were performed bilaterally to document corneal morphology. Results Affected family members presented with different stages of aniridic keratopathy, with a corneal appearance varying from totally transparent to opaque and highly vascularised. Increased corneal thickness in affected members, particularly those with severe keratopathy, was noted by ASOCT. By IVCM, opaque corneas were characterized by active vessels and dense inflammatory cell infiltration. In corneas with milder keratopathy, pathologic epithelial findings included epithelial pleomorphism, focal epithelial opacities, and an absence of limbal epithelial crypts and focal stromal projections at the limbus. Nerves of the anterior cornea exhibited several distinct features, including an unusually close association of subbasal nerves with epithelial cells, an unusually high subbasal nerve density with highly branched nerves, and a prominent whorl region. Additionally, abnormally dense and tortuous anterior stromal nerves, attached to stromal keratocytes, were noted in unaffected members. Conclusion Altered epithelial morphology and a vigorous innervation of the anterior cornea were the most pronounced corneal findings in family members with milder forms of aniridic keratopathy. Further findings confirmed the known increase in corneal thickness and limbal stem cell abnormality in aniridia.

Straylight and corneal edema

Abstract Purpose It is known that corneal edema is associated to increased light scatter. It was the purpose of this study to calculate the intensity and angular distribution of scattered light in a series of corneal samples at different hydration, using a sensitive optical technique. Methods Sixteen fresh porcine eyes were obtained from a local abattoir. To isolate the role of corneal stroma the the epithelium was carefully removed with a mechanical brush. The central 8 mm of each cornea was harvested using a Barron's PKP trephine. To establish corneal hydration, corneal buttons were immersed in Dextran (300kDa) solutions, with concentrations ranging from 5 to 20% w/w, for at least 3 hours. The intensity and angular distribution of scattered light was measured for all corneas by means of a purposely‐developed camera lens that incorporated excised corneas between its glass elements. This lens was used with a CCD camera to record images projected on a computer screen. Before scatter measurements the thichness of each corneal sample was measured by means of a mechanical pachymeter (Mitutoyo IDC 112T, Japan). Results The mean scatter coefficients for the corneas at normal hydration levels was 0.22 (SD=0.059). This value was effectively double (0.46 ; SD= 0.048) at a moderate increase of stromal thickness by 17% and reached a value of 0.56 (SD=0.079) at a relative increase of corneal thickness of 62%. The angular distribution did not significantly deppend on hydration. Conclusion Scattered light intensity increases with corneal edema. Even small changes in corneal hydration affect significantly the narrow angle light scattering properties of corneal stroma.

Corneainacromegalic patientsasapossible target of growth hormone action

GH exerts its effects on many organs and the eye also seems to be a target site, although few authors have investigated the corneal thickness in patients with acromegaly. To perform a detailed ophthalmological evaluation in acromegalic patients, in relation to disease activity. Twenty-eight acromegalic patients (11 males, 17 females) and 22 voluntary healthy subjects underwent complete metabolic and ophthalmological evaluation, including retinal thickness (RT), central corneal thickness (CCT), and intraocular pressure values (IOP). Significantly greater CCT values were found in all acromegalic patients in comparison with controls (567 vs 528.5 μm; p<0.001), without concomitant greater corrected IOP. No difference was found for RT. Analyzing these data according to disease activity, uncontrolled patients showed greater CCT values (573.5 vs 559 μm; p=0.002) and corrected IOP (17.4 vs 16 mmHg; p=0.001) than the controlled ones. CCT also correlated with basal and nadir GH after oral glucose load levels, IGF-I levels, and duration of active disease. Acromegaly is characterized by greater CCT values, supporting the hypothesis that GH excess may have stimulatory effects on the cornea as well as on other target organs. Higher GH levels, disease control status and duration of active disease seem to be the main causes of increased corneal thickness. We suggest a careful and detailed corneal evaluation in acromegalic patients to prevent the potential risk of increased IOP, in addition to the already-known complications.

Evaluation of anterior segment parameter changes using the Pentacam after uneventful phacoemulsification

This study set out to evaluate the influences of uneventful phacoemulsification on the anterior segment parameters obtained with the Pentacam rotating Scheimpflug camera and intraocular pressure (IOP). A total of 42 eyes of 34 patients (26 men, eight women) were evaluated preoperatively, and at 1, 3 and 6 months postoperatively with the Pentacam. Intraocular pressure was measured with the Goldmann applanation tonometer. The non-parametric paired t-test was used to compare preoperative and 1-, 3- and 6-month postoperative measurements of anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA) width, central corneal thickness (CCT), the central 3-, 5- and 7-mm corneal volume (CV), pupil size, and IOP. Pearson's correlation test was used to evaluate the relationships between IOP and ACD, ACV and ACA width. The differences between ACD, ACV, ACA and IOP values taken preoperatively and those taken postoperatively at 1, 3 and 6 months were statistically significant (p<0.05). The differences between CCT, central 3-, 5- and 7-mm CV, and pupil size measurements taken preoperatively and those taken postoperatively at 1, 3 and 6 months were not statistically significant (p>0.05). The decrease in IOP was not correlated with the changes in ACD, ACV and ACA (p>0.05). Uneventful phacoemulsification significantly reduced IOP, increased ACD and ACV, and widened the ACA. However, alterations in CV, CCT and pupil size values were not statistically significant. Alterations in ACD, ACV, ACA and IOP remain stable after the first month of surgery.

Comparison of Data From the Rostock Cornea Module of the Heidelberg Retina Tomograph, the Oculus Pentacam, and the Endothelial Cell Microscope

The aim of this study was to validate data arising from the Rostock Cornea Module (RCM) of the Heidelberg Retina Tomograph. Morphological parameters of the cornea were analyzed according to their dependency on patient's age. RCM measurements of 60 healthy eyes within 2 different age groups (group 1 <35 years, group 2 >50 years) were compared with the corneal thickness determined by the Oculus Pentacam and the endothelial cell density measured by the Tomey endothelial microscope, EM-2000. The mean corneal thickness measured with the Heidelberg Retina Tomograph/RCM was 517 +/- 31 microm and 542 +/- 30 microm with the Oculus Pentacam (correlation coefficient, R = 0.78). Group 1 showed a corneal thickness of 509 +/- 24 microm with the RCM and 531 +/- 27 microm with the Pentacam. In group 2, the corneal thickness was 525 +/- 34 microm and 553 +/- 29 microm, respectively. A significant increase in corneal thickness for older patients could be shown. The differences between the methods and the age groups were statistically significant (P < 0.0001). The average endothelial cell density measured with the RCM was 2779 +/- 472 cells per square millimeter. Between the age groups and the methods (RCM and endothelial microscope), no statistically significant differences could be found. Cell densities for the epithelial cell layers and keratocytes showed no significant correlation with age and sex of the patients. The RCM provides a reliable procedure for the evaluation of all corneal layers including morphological parameters. Endothelial cell densities either determined with the RCM or the EM-2000 are generally comparable to each other and showed no significant differences. It is suggested that lower corneal thickness measurements of the RCM can be caused by pressure during examination. An increased corneal thickness in the older group could be determined with the RCM and the Oculus Pentacam.

Acquired central corneal thickness increase over time after removal of childhood cataracts: A prospective, longitudinal study

Introduction: Central corneal thickness (CCT) is increased in aphakic/pseudophakic eyes compared with normals. Intraocular pressure (IOP) measurement in these eyes with glaucoma/glaucoma suspect status is critical to their evaluation/management, yet the nature and impact of abnormal CCT in these children remains controversial. Hypothesis: CCT becomes elevated in pediatric eyes after cataract removal, and this acquired tendency is accentuated in eyes with glaucoma.

Comparison of Torsional and Microburst Longitudinal Phacoemulsification: A Prospective, Randomized, Masked Clinical Trial

To compare intraoperative performance and postoperative outcome of three phacoemulsification technologies in patients undergoing microcoaxial phacoemulsification through 2.2-mm corneal incisions. The prospective, randomized, single-masked study included 360 eyes randomly assigned to torsional (Infiniti Vision System; Alcon Laboratories, Fort Worth, TX), microburst with longitudinal (Infiniti), or microburst with longitudinal (Legacy Everest, Alcon Laboratories) ultrasound. Assessments included surgical clock time, fluid volume, and intraoperative complications, central corneal thickness on day 1 and months 1 and 3 postoperatively, and endothelial cell density at 3 months postoperatively. Comparisons among groups were conducted. Torsional ultrasound required significantly less surgical clock time and fluid volume than the other groups. There were no intraoperative complications. Change in central corneal thickness and endothelial cell loss was significantly lower in the torsional ultrasound group at all postoperative visits (P < .001, Kruskal-Wallis test) compared to microburst longitudinal ultrasound modalities. Torsional ultrasound demonstrated quantitatively superior intraoperative performance and showed less increase in corneal thickness and less endothelial cell loss compared to microburst longitudinal ultrasound.

LASIK Flap Creation With the Ziemer Femtosecond Laser in 787 Consecutive Eyes

To present the flap characteristics and short-term efficacy and safety of 787 consecutive LASIK procedures with the FEMTO LDV femtosecond laser (Ziemer Ophthalmic Systems) for the treatment of refractive errors. Seven hundred eighty-seven consecutive eyes of 405 previously non-operated patients were treated with the FEMTO LDV. Intended flap thickness was 110 microm and intended flap diameter varied from 8.5 to 9.5 mm. Refractive treatment was performed with the WaveLight ALLEGRETTO WAVE Concerto 500 Hz excimer laser. All eyes were wavefront-optimized. The mean flap thickness, measured by ultrasound pachymetry, was 90.0+/-5.5 microm (range: 67 to 107 microm) in right eyes and 90.1+/-4.6 microm (range: 77 to 106 microm) in left eyes. Mean flap diameter was 9.1+/-0.2 mm (range: 8.4 to 9.9 mm) in right eyes and 9.1+/-0.2 mm (range: 8.0 to 10.0 mm) in left eyes. Increasing flap thickness was correlated with increasing corneal thickness in right eyes and flatter keratometric value K(1) in left eyes. The most common complication was minor bleeding during the procedure (12.7%). All other complications were rare (8.4%), and none prevented further laser ablation. The Ziemer FEMTO LDV laser created thinner LASIK flaps than intended but with a low standard deviation and minimal intraoperative complications.

Optic Disc Diameter Increases during Acute Elevations of Intraocular Pressure

To evaluate optic nerve diameter changes in glaucomatous and nonglaucomatous eyes during transient elevation of intraocular pressure (IOP). This prospective experimental study included 100 subjects: 38 with glaucoma and 62 without glaucoma. Elevation of IOP to an average of 64 mm Hg for less than 30 seconds was induced in one eye of all subjects by means of a modified LASIK suction ring. The optic nerve heads were imaged before and during the elevation. During IOP elevation, optic disc area and linear disc measurements increased by a small but significant amount (3.89%, P < 0.0001 and 0.96%, P = 0.01, respectively). Distances between retinal landmarks did not change significantly (P = 0.25). A smaller optic disc at baseline (P = 0.004) and increased central corneal thickness (CCT; P = 0.011) were associated with a greater increase in disc area relative to other fundus dimensions during IOP elevation. Disc area increased less in patients with glaucoma (P = 0.015). In a multivariate model including age, glaucoma status, CCT, and baseline disc area, there was a small but significant negative correlation between disc area enlargement and baseline optic disc diameter (P = 0.017). Transient elevation of IOP in adult eyes resulted in increases in disc area and linear disc dimensions, but not in retinal dimensions. The degree of enlargement appears to be less in patients with glaucoma than without and greater with increased corneal thickness. A multivariate model showed that the amount of disc area increase was inversely proportional to baseline disc area but was not related to glaucoma status or CCT. (ClinicalTrials.gov number, NCT00328835).

Central and peripheral oxygen transmissibility thresholds to avoid corneal swelling during open eye soft contact lens wear

This study was designed to derive central and peripheral oxygen transmissibility (Dk/t) thresholds for soft contact lenses to avoid hypoxia-induced corneal swelling (increased corneal thickness) during open eye wear. Central and peripheral corneal thicknesses were measured in a masked and randomized fashion for the left eye of each of seven subjects before and after 3 h of afternoon wear of five conventional hydrogel and silicone hydrogel contact lens types offering a range of Dk/t from 2.4 units to 115.3 units. Curve fitting for plots of change in corneal thickness versus central and peripheral Dk/t found threshold values of 19.8 and 32.6 units to avoid corneal swelling during open eye contact lens wear for a typical wearer. Although some conventional hydrogel soft lenses are able to achieve this criterion for either central or peripheral lens areas (depending on lens power), in general, no conventional hydrogel soft lenses meet both the central and peripheral thresholds. Silicone hydrogel contact lenses typically meet both the central and peripheral thresholds and use of these lenses therefore avoids swelling in all regions of the cornea.

Light and electron microscopic evaluation of canine corneal endothelium following CO2 photokeratotomy

To determine using light and scanning electron microscopy if treatment with CO2 photokeratotomy alters the corneal endothelium in healthy dogs. Eight surgery laboratory dogs were determined to be free of ocular abnormalities. Under general anesthesia, the left eye of each dog was treated in a quadrant from 12 to 3 o'clock with the CO(2) laser in a defocused mode. The right eye served as a control. There were four treatment groups, each with 2 dogs: group 1 (2 W, 0.1 J/s, 0.8 mm tip), group 2 (3 W, 0.3 J/s, 0.8 mm tip), group 3 (2 W, 0.04 J/s NovaScan), group 4 (3 W, 0.06 J/s, NovaScan). The 0.8 mm tip delivered a power density of 382 W/cm(2) or 573 W/cm(2), at 2 or 3 watts respectively. The NovaScan handpiece delivered a power density of 30 W/cm(2) or 40 W/cm(2), at 2 or 3 Watts respectively. Following euthanasia, right and left corneas including a 2-mm scleral rim were harvested and fixed in commercial grade Karnovsky's fixative. One piece of cornea was processed routinely, embedded in Embed 812 resin, sectioned at 1 um, stained with toluidine blue and evaluated with the light microscope. A separate piece of each cornea was routinely processed and examined with a JEOL 6400 scanning electron microscope (SEM) at 20 KV. No changes in endothelial cell morphology were detected by light microscopy in the sections examined. SEM indicated normal endothelial cell morphology in control eyes with presumed artifactual changes at the corneal free margin (4/8 eyes). Multiple punctate to linear regions of endothelial cell destruction were observed in 6/8 laser-treated corneas. A significant increase in corneal thickness ranging from 1.90 to 37.28% was observed in all laser treated corneas. This increase in thickness correlated linearly with the degree of endothelial damage. Ultrastructural findings also correlated with postoperative clinical findings. CO2 laser photokeratotomy alters corneal endothelial cell morphology and thickness.

Use of ultrasonic pachymetry for measurement of changes in corneal thickness in mouse corneal transplant rejection

Background/aimsDiagnosis of rejection in the mouse model of corneal transplantation is based on subjective judgement of loss of graft transparency. The aims of this study were to (1) evaluate a...

Contact Lens-Induced Keratitis Resembling Central Toxic Keratopathy Syndrome

To document a case of contact lens-induced keratitis resembling central toxic keratopathy syndrome. A 23-year-old female developed an acute, central, stromal haze subsequent to soft contact lens overwear. Slit lamp examination revealed corrugated stromal "mud cracks," as seen in stage IV diffuse lamellar keratitis (DLK). This was accompanied by relative corneal thinning and flattening with a hyperopic shift of approximately 6 diopters. Eight weeks after discontinuing contact lens wear and after a 2-week tapering regimen of topical steroids, she had partial resolution of the central haze, partial increase in corneal thickness, steepness, and decrease in hyperopic shift. The authors present a case with a history of soft contact lens overwear and a clinical presentation notably similar to the central toxic keratopathy syndrome, which has recently been reported after laser refractive surgery.