Comparison of corneal measurements in keratoconus eyes with two swept-source-optical coherence tomography devices and a Scheimpflug device.

PURPOSE: To assess the feasibility and reliability of biometric measurements taken with the Eyestar 900 device in keratoconus eyes in comparison with those taken with the Pentacam HR and IOLMaster 700. METHODS: Seventy-five eyes of 75 patients with keratoconus were included. The central corneal thickness (CCT), thinnest point of corneal thickness (TCT), axial length (AL), flat (K1) and steep (K2) anterior and posterior (Kp1, Kp2) keratometry, maximal keratometry (KMax) and anterior chamber depth (ACD) were compared between the Eyestar 900, Pentacam HR and IOLMaster 700. Reliability parameters such as the coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were calculated. Pearson's r was determined to assess the correlation between devices. RESULTS: A high repeatability (CoV < 1%) and intraclass correlation (ICC > 0.9) was found for all devices, led by AL, TCT, K1 and K2 (CoV 0.01-0.36%; ICC 0.994-1.00). The largest correlation between devices was found for AL (Eyestar vs. IOLMaster, r = 1.0), K1 (Eyestar vs. IOLMaster, r = 0.997) and ACD (Eyestar vs. IOLMaster, r = 0.995; Pentacam vs. IOLMaster, r = 0.987; Eyestar vs. Pentacam, r = 0.983), but there were significant differences in measured values between devices (p < 0.001), whereas the correlation was only slightly lower (r = 0.947 to 0.994) for KMax, CCT, TCT, K2, Kp1 and Kp2. CONCLUSION: Keratometric and axial length measurements with the Eyestar 900 were feasible and revealed a high repeatability and a good correlation to the other devices in eyes with keratoconus.

The influence of hydration on different mechanical moduli of the cornea.

PURPOSE: To determine the interrelation of different elastic moduli of the cornea and to investigate their dependency on corneal hydration. METHODS: Rabbit eyes were divided into four groups. Corneas were excised and mounted into a Barron artificial anterior chamber. Various corneal hydration steady states were achieved with different dextran T-500 concentrations in the anterior chamber, as well as on the corneal anterior surface. The treatment-solutions of each group contained either 5, 10, 15, or 20% w/w dextran. Ultrasound pachymetry was used to measure central corneal thickness. Brillouin microscopy of the central cornea determined the longitudinal bulk modulus by means of Brillouin frequency shift. Subsequently, a 5-mm-wide central strip was taken for extensiometry to measure the tangential elastic modulus. RESULTS: The longitudinal bulk modulus was 1.2-times higher in corneas dehydrated with 20% dextran compared to those hydrated with 5% dextran. In contrast, the tangential elastic modulus increased by 4.4 times. The obtained longitudinal bulk moduli were two orders of magnitude bigger than the tangential elastic moduli. Regression analysis of longitudinal bulk modulus and tangential elastic modulus revealed a quadratic relation. The bulk modulus seemed to be independent of tension, whereas the elastic modulus was tension-dependent. Greater corneal hydration led to significantly thicker pachymetry. CONCLUSION: Corneal biomechanics are highly dependent on the level of corneal hydration. Surprisingly, tangential elastic moduli were more sensitive to hydration changes than longitudinal bulk moduli. A quadratic relation was found between both moduli.

Prospective study of foveal thickness alterations after cataract surgery assessed by optical coherence tomography.

BACKGROUND/AIMS: To evaluate the alterations of mean foveal thickness (MFT) and visual acuity (VA) outcomes after uncomplicated cataract surgery in different groups of patients. METHODS: This study included eyes of consecutive patients who underwent cataract surgery between November 2007 and June 2009. The patients included in the study were divided into 4 groups, as follows: history-free patients, patients with diabetes mellitus without macular involvement at baseline, patients with glaucoma, and patients with epiretinal membrane (ERM). Preoperatively and at 1, 3 and 6 months postoperatively, patients were evaluated for MFT by optical coherence tomography at the central 1-mm macular zone and for logarithm of the minimum angle of resolution best spectacle-corrected VA (BSCVA). RESULTS: A total of 202 eyes were included in the study. MFT values demonstrated a statistically significant increase (p < 0.01) after cataract surgery in all groups at the first and third postoperative month. The history-free (p = 0.09) and glaucoma (p = 0.19) groups did not demonstrate a statistically significant difference in MFT values between the preoperative and 6-month measurements. MFT values 6 months after cataract surgery in the diabetes and ERM groups remained significantly higher (p < 0.01). Despite these findings, VA increased significantly (p < 0.01) in all groups at all postoperative follow-ups. CONCLUSIONS: MFT values increased significantly in all groups at the first and third months after cataract surgery. At 6 months, MFT values returned to preoperative levels in the history-free and glaucoma patients, while they remained significantly higher in the diabetic and ERM patients. Despite these macular alterations, BSCVA improved significantly after cataract surgery in all groups at all postoperative follow-ups.

Impact of cerebral hypoperfusion-reperfusion on optic nerve integrity and visual function in the DBA/2J mouse model of glaucoma.

OBJECTIVE: One of the most important risk factors for developing a glaucomatous optic neuropathy is elevated intraocular pressure. Moreover, mechanisms such as altered perfusion have been postulated to injure the optical path. In a mouse model, we compare first negative effects of cerebral perfusion/reperfusion on the optic nerve structure versus alterations by elevated intraocular pressure. Second, we compare the alterations by isolated hypoperfusion-reperfusion and isolated intraocular pressure to the combination of both. METHODS AND ANALYSIS: Mice were divided in four groups: (1) controls; (2) perfusion altered mice that underwent transient bi-common carotid artery occlusion (BCCAO) for 40 min; (3) glaucoma group (DBA/2J mice); (4) combined glaucoma and altered perfusion (DBA/2J mice with transient BCCAO). Optic nerve sections were stereologically examined 10-12 weeks after intervention. RESULTS: All experimental groups showed a decreased total axon number per optic nerve compared with controls. In DBA/2J and combined DBA/2J & BCCAO mice the significant decrease was roughly 50%, while BCCAO leaded to a 23% reduction of axon number, however reaching significance only in the direct t-test. The difference in axon number between BCCAO and both DBA/2J mice was almost 30%, lacking statistical significance due to a remarkably high variation in both DBA/2J groups. CONCLUSION: Elevated intraocular pressure in the DBA/2J mouse model of glaucoma leads to a much more pronounced optic nerve atrophy compared with transient forebrain hypoperfusion and reperfusion by BCCAO. A supposed worsening effect of an altered perfusion added to the pressure-related damage could not be detected.

In vivo measurement of central corneal thickness in normal chicks (Gallus gallus domesticus) with the optical low-coherence reflectometer.

OBJECTIVE: To determine the practicability and accuracy of central corneal thickness (CCT) measurements in living chicks utilizing a noncontact, high-speed optical low-coherence reflectometer (OLCR) mounted on a slit lamp. ANIMALS STUDIED: Twelve male chicks (Gallus gallus domesticus). Procedures Measurements of CCT were obtained in triplicate in 24 eyes of twelve 1-day-old anaesthetized chicks using OLCR. Every single measurement taken by OLCR consisted of the average result of 20 scans obtained within seconds. Additionally, corneal thickness was determined histologically after immersion fixation in Karnovsky's solution alone (20 eyes) or with a previous injection of the fixative into the anterior chamber before enucleation (4 eyes). RESULTS: Central corneal thickness measurements using OLCR in 1-day-old living chicks provide a rapid and feasible examination technique. Mean CCT measured with OLCR (189.7 ± 3.34 µm) was significantly lower than histological measurements (242.1 ± 47.27 µm) in eyes with fixation in Karnovsky's solution (P = 0.0005). In eyes with additional injection of Karnovsky's fixative into the anterior chamber, mean histologically determined CCT was 195.2 ± 8.25 µm vs. 191.9 ± 8.90 µm with OLCR. A trend for a lower variance was found compared to the eyes that had only been immersion fixed. CONCLUSION: Optical low-coherence reflectometry is an accurate examination technique to measure in vivo CCT in the eye of newborn chicks. The knowledge of the thickness of the chick cornea and the ability to obtain noninvasive, noncontact measurements of CCT in the living animal may be of interest for research and development of eye diseases in chick models.

Oxygen Kinetics During Corneal Cross-linking With and Without Supplementary Oxygen.

PURPOSE: To measure and simulate oxygen kinetics during corneal cross-linking at different irradiances with and without supplementary oxygen. DESIGN: Experimental, laboratory study. METHODS: In de-epithelialized porcine eyes, a femtosecond-laser-generated tunnel was used to place a fiber probe in corneal depths of 100, 200, and 300 µm to measure the local oxygen concentration. After riboflavin imbibition, the corneas were irradiated at 3, 9, 18, and 30 mW/cm2 while the oxygen concentration was measured. All experiments were performed under normoxic (21%) and hyperoxic (>95%) conditions. The obtained data were used to identify parameters of a numerical model for oxygen consumption and diffusion. RESULTS: The equilibrium stromal oxygen concentration under atmospheric oxygen at 3 mW/cm2 was 2.3% in 100 µm decreasing to <1% in 300 µm. With 9, 18, and 30 mW/cm2, no oxygen was available in 200 µm, respectively, 100 µm or deeper. Using a hyperoxic environment, the concentration was 50% using 3 mW/cm2 in 100 µm, decreasing to 40% in 300 µm. At 9 mW/cm2, the concentrations were 5%, 3%, and 1% in 100, 200 and 300 µm, respectively. Using 18 and 30 mW/cm2, all oxygen was depleted at 100 µm; however, oxygen half-lives were longer at 18 mW/cm2 than at 30 mW/cm2. The oxygen model was able to reproduce the experiments and indicated an exponential decay with increasing distance to the anterior surface. CONCLUSION: Supplementary oxygen increases the oxygen availability during corneal cross-linking. At higher irradiances, supplementary oxygen is beneficial and eliminates the bottleneck of oxygen allowing a potentially more efficient cross-linking. The calibrated numerical model can quantify the spatial oxygen concentration related to different scenarios such as irradiance or environmental oxygen concentration.

Antifibrotic effects of tocotrienols on human Tenon's fibroblasts.

PURPOSE: To compare the antifibrotic effect of vitamin E isoforms alpha-, gamma-, and delta-tocotrienol on human Tenon's fibroblasts (hTf) to the antimetabolite mitomycin C. METHODS: Antifibrotic effects of alpha- (40, 60, 80, 100, and 120 microM), gamma- (10, 20, 30, and 40 microM) and delta-tocotrienol (10, 20, 30, and 40 microM) on hTf cultures were evaluated by performing proliferation, migration and collagen synthesis assays. Whereas for vitamin E the exposure time was set to 7 days to mimic subconjunctival application, cultures were exposed only 5 min to mitomycin C 100 microg/ml to mimic intraoperative administration. Cell morphology (phase contrast microscopy) as an assessment for cytotoxicity and cell density by measuring DNA content in a fluorometric assay to determine proliferation inhibition was performed on day 0, 4, and 7. Migration ability and collagen synthesis of fibroblasts were measured. RESULTS: All tested tocotrienol isoforms were able to significantly inhibit hTf proliferation in a dose-dependent manner (maximal inhibitory effect without relevant morphological changes at day 4 for alpha-tocotrienol 80 microM with 36.7% and at day 7 for alpha-tocotrienol 80 microM with 42.6% compared to control). Degenerative cell changes were observed in cultures with concentrations above 80 microM for alpha- and above 30 microM for gamma- and delta-tocotrienol. The highest collagen synthesis inhibition has been found with 80 microM alpha-tocotrienol (62.4%) and no significant inhibition for mitomycin C (2.5%). Migration ability was significantly reduced in cultures exposed to 80 microM alpha- and 30 microM gamma-tocotrienol (inhibition of 82.2% and 79.5%, respectively, compared to control) and also after mitomycin C treatment (60.0%). Complete growth inhibition without significant degenerative cell changes could only be achieved with mitomycin C. CONCLUSION: In vitro, all tested tocotrienol isoforms were able to inhibit proliferation, migration and collagen synthesis of human Tenon's fibroblasts and therefore may have the potential as an anti-scarring agent in filtrating glaucoma surgery.

Efficacy of Amniotic Membrane Transplantation for the Treatment of Corneal Ulcers.

PURPOSE: To evaluate the outcome of amniotic membrane transplantation (AMTX) as a treatment for corneal ulcers. METHODS: Patients treated with AMTX for refractory corneal ulcers between 2012 and 2017 were evaluated in a retrospective analysis. Primary outcome measure was complete reepithelialization. RESULTS: A total of 149 patients were included (mean age 68 ± 18 years). The mean duration between ulcer onset and AMTX was 42 ± 46 days. The longest time between ulcer diagnosis and AMTX was found in bacterial ulcers and the shortest time to AMTX in eyes with trauma/chemical burns (mean 65 ± 15 days and 14 ± 4 days, respectively). In 70% of the patients, a single AMTX procedure was sufficient to achieve epithelial closure (21% <1 month, 40% within 1 -3 months, and 9% within 3-6 months). Treatment failure was observed in 30% of all patients, and most of them underwent further interventions. Highest closure rates were found in bacterial ulcers, herpetic ulcers, and neurotrophic ulcers (80%, 85%, and 93%, respectively), whereas the lowest reepithelialization rates were found in ulcers after corneal surgery and ulcers associated with rheumatic disease (52% and 57%, respectively). CONCLUSIONS: AMTX is a valuable treatment option to achieve corneal epithelial wound healing in cases refractory to conventional treatment. Success rates differ depending on the etiology of ulcer.

Comparison and evaluation of ocular biometry using a new noncontact optical low-coherence reflectometer.

PURPOSE: To evaluate a new high-resolution noncontact biometer (Lenstar; Haag-Streit AG, Koeniz, Switzerland) using optical low-coherence reflectometry and to compare the clinical measurements with those obtained from the IOLMaster (Carl Zeiss, Jena, Germany) and the Pachmumeter (Haag-Streit AG). DESIGN: Exploratory evaluation of diagnostic technology and nonrandomized, prospective clinical trial. PARTICIPANTS: Eighty subjects (144 eyes) aged 20 to 90 years with cataractous, pseudophakic, aphakic, silicon oil-filled, or normal eyes. METHODS: Measurements of axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), corneal radius (R1 [flattest radius of corneal curvature] and R2 [steep radius, 90 degrees apart from R1]), and axis of the flattest radius (Ax1) obtained with the Lenstar were compared with those obtained with the IOLMaster or Pachmumeter. The results were evaluated using Bland-Altman analyses. The differences between both methods were assessed using the paired t test, and its correlation was evaluated by Pearson coefficient. MAIN OUTCOME MEASURES: Axial length, CCT, ACD, R1, R2, and Ax1. RESULTS: The overall mean AL measured with the Lenstar and the IOLMaster was 24.1 mm (r = 0.999). Anterior chamber depth was 3.19 mm (Lenstar) and 3.17 mm (IOLMaster; r = 0.875). Excellent correlations also were found for the corneal radius and the axis of flattest radius (R1, r = 0.927; R2, r = 0.929; and Ax1, r = 0.938). Mean CCT was 0.557 mm (r = 0.978) for both Lenstar and Pachmumeter. CONCLUSIONS: Measurements with the new Lenstar correlated well with those with the IOLMaster and Pachmumeter in cataractous, pseudophakic, aphakic, silicon oil-filled, and normal eyes. It is an accurate, fast instrument that provides additional information of interest to any cataract or refractive surgeon.

Dietary tocopherol supplementation after trabeculectomy and phacotrabeculectomy: double-blind randomized placebo-controlled trial.

PURPOSE: The vitamin E compound alpha-tocopherol inhibits fibroblast growth in vitro. To evaluate its potential benefit in preventing failure of glaucoma filtration surgery, we prospectively investigated the outcome of filtering surgery with postoperative dietary alpha-tocopherol supplementation. PATIENTS AND METHODS: Thirty-nine patients (39 eyes) with primary open-angle glaucoma or pseudoexfoliative glaucoma were randomly assigned to two post-(phaco)-trabeculectomy treatment groups. Daily oral intake of 300 mg alpha-tocopheryl-acetate (absorbed as alpha-tocopherol in the intestine) for 2 months was compared to a placebo preparation in a double-blind trial. The follow-up time was 1 year. Success was defined as intraocular pressure (IOP)

Riboflavin Concentrations at the Endothelium During Corneal Cross-Linking in Humans.

Purpose: To determine the riboflavin concentration in the posterior corneal stroma, Descemet's membrane, and endothelium prior to UV irradiation in corneal cross-linking (CXL) in humans. Methods: Five human deepithelialized cadaver corneas were mounted into artificial anterior chambers. After the establishment of stable physiological hydration, two-photon imaging with a certified multiphoton tomograph was used to determine fluorescence intensity and second harmonic generation signals from collagen throughout each cornea by optical sectioning, with a step size of 2.5 µm. Afterward, 0.1% riboflavin solution was applied to the anterior corneal surface, similar to the standard CXL protocol. To determine the absolute riboflavin concentration immediately before UV irradiation, corneas were measured by two-photon imaging just at the end of the riboflavin imbibition and after riboflavin saturation. Results: The topical application of 0.1% riboflavin results in a riboflavin concentration that decreases to 0.035% in the posterior stroma. Inside Descemet's membrane and endothelium, the concentration drops further to only approximately 0.015% at the endothelial level. Local riboflavin distribution indicates a predominantly paracellular passive diffusion of riboflavin into the anterior chamber. Conclusion: The experimentally determined riboflavin concentration of 0.015% at the endothelium shows a substantial discrepancy of a factor of 1.7 to the previously theoretically calculated 0.025%. A lower riboflavin concentration at the endothelium may enable higher radiant exposures and further improve the efficacy of CXL.

Dynamic contour tonometry in keratoconus and postkeratoplasty eyes.

PURPOSE: To compare the performance of dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in measuring intraocular pressure in eyes with irregular corneas. METHODS: GAT and DCT measures were taken in 30 keratoconus and 29 postkeratoplasty eyes of 35 patients after pachymetry and corneal topography. Regression and correlation analyses were performed between both tonometry methods and between tonometry methods and corneal parameters. Bland-Altman plots were constructed. RESULTS: DCT values were significantly higher than GAT values in both study groups: +4.1 +/- 2.3 mm Hg (mean +/- SD) in keratoconus and +3.1 +/- 2.5 mm Hg after keratoplasty. In contrast to DCT, GAT values were significantly higher in postkeratoplasty eyes than in keratoconus. The correlation between the 2 tonometry methods was moderate in keratoconus (Kendall correlation coefficient, tau = 0.34) as well in postkeratoplasty eyes (tau = 0.66). The +/-1.96 SD span of the DCT-GAT differences showed a considerable range: -0.42 to +8.70 mm Hg in keratoconus and -1.87 to +7.98 mm Hg in postkeratoplasty eyes. In the keratoconus group, neither DCT nor GAT correlated significantly with any of the corneal parameters. In the postkeratoplasty group, both DCT and GAT measures showed a moderate positive correlation with corneal steepness, but only DCT had a significant negative correlation with the central corneal thickness (tau = -0.33). CONCLUSIONS: DCT measured significantly higher intraocular pressures than GAT in keratoconus and postkeratoplasty eyes. DCT and GAT measures varied considerably, and DCT was not less dependent on biomechanical properties of irregular corneas than GAT.

Keratoconus Progression After Corneal Cross-Linking in Eyes With Preoperative Maximum Keratometry Values of 58 Diopters and Steeper.

PURPOSE: To evaluate the effectiveness of cross-linking (CXL) in treating keratoconus eyes with Kmax values ≥58.0 D. METHODS: Retrospective analysis of outcomes of standard Dresden epi-off CXL in progressive keratoconus with preoperative Kmax ≥58.0 Diopters (D). Inclusion criteria were Kmax ≥58.0 D and minimum follow-up of 1 year. Corneal topography and tomography were performed preoperatively and at 1 and 2 years. Sixty-one eyes of 56 patients with mean age of 24.9 ± 8.6 years (mean ± SD, range 12-57 years) had 1-year follow-up. Fifty of these eyes had 2-year follow-up. The definition of progression was an increase in Kmax of ≥1.0 D over 1 year. RESULTS: Mean Kmax was 63.9 ± 6.1 D (mean ± SD, range 58.2-87.0 D) preoperatively (n = 61) and 62.9 ± 5.9 D (range 54.6-82.5 D) after 1 year. This represented a significant decrease in steepness (P = 0.0029). Mean pachymetry decreased significantly from 433.7 ± 44.8 µm preoperatively to 423.0 ± 41.8 µm (P = 0.001) at 1 year. Progression occurred in 14 of the 61 eyes (23%) at 1 year, and 5 (8.2%) steepened more than 2.0 D. In the group with 2-year follow-up, mean Kmax was 63.0 ± 5.0 D (range 58.2-87 D) before CXL and decreased to 61.5 ± 4.8 D (range 53.6-78.3 D) at 2 years (P = 0.001). Nine of the 50 eyes (18%) showed an increase of Kmax of ≥ 1 D. CONCLUSIONS: The incidence of progression (23% at 1 and 18% at 2 years, respectively) is considerably higher than in previously reported results of CXL in eyes with mean Kmax ≥58.0 D. To the best of our knowledge, this study represents the largest number of such steep corneas analyzed with respect to long-term progression after CXL.

Cataract significantly influences quantitative measurements on swept-source optical coherence tomography angiography imaging.

PURPOSE: To analyze retinal blood flow before and after cataract surgery using swept-source optical coherence tomography angiography (SS-OCTA). METHODS: Prospective observational study. Consecutive patients were recruited and scanned using SS-OCTA before and after cataract surgery. Laser flare photometry were performed post-surgery. Perfusion and vessel density of superficial (SCP) and deep capillary plexuses (DCP) of the 3 × 3 mm images as well as foveal avascular zone (FAZ) measurements were assessed. Vessel continuity, vessel visibility and presence of artefacts were evaluated by two blinded graders using a predefined grading protocol. RESULTS: Thirteen eyes of 12 patients met the inclusion criteria. There was a significant increase of perfusion and vessel densities in both the SCP and the DCP after cataract surgery within the 3 × 3 mm images. Significantly better distinguishability of FAZ border was observed postoperatively in both SCP and DCP, however, FAZ area and perimeter measurements did not significantly change after cataract surgery. Mean number of motion artifacts in SCP and DCP numerically decreased by 37% (P = .089) and 42% (P = .080). CONCLUSIONS: Lens opacities have a significant influence on retinal blood flow measurements in SS-OCTA and should be considered in quantitative vessel analysis. Inflammation may also impact the assessment of density parameters. FAZ measurements seems to be the most robust parameters in terms of media opacity.

Distribution of amyloid precursor protein and amyloid-beta immunoreactivity in DBA/2J glaucomatous mouse retinas.

PURPOSE: Evidence suggests that altered metabolism of amyloid precursor protein (APP) may play a role in the pathophysiology of retinal ganglion cell (RGC) death in the etiology of glaucoma. The authors sought to determine the distribution of APP and amyloid-beta (Abeta) in DBA/2J glaucomatous mouse retinas. METHODS: The retinas of 3- and 15-month-old DBA/2J mice and C57/BL-6 mice (control group) were fixed with 4% paraformaldehyde and processed for immunohistochemistry. Antibodies used included a polyclonal antibody to the C terminus of Abeta 40 and a polyclonal antibody to the APP ectodomain. Immunohistochemically stained tissue was graded using light microscopy. Distribution and semiquantitative expression of APP and Abeta in young and old glaucomatous and normal retinas were determined and compared. RESULTS: Strong APP and Abeta immunoreactivity was found in the RGC layer, optic nerve, and pia/dura of old DBA/2J retinas, with considerably higher intensity found in the old compared with the young DBA/2J mice. In contrast to glaucomatous mice, the control group did not show any notable age-related difference. CONCLUSIONS: Disruption of the homeostatic properties of secreted APP with consecutive Abeta cytotoxicity might be a contributing factor of ganglion cell loss in glaucomatous mouse retinas.

Bilateral central crystalline corneal deposits four years after intacs for myopia.

PURPOSE: To report a case of bilateral central crystalline keratopathy in the anterior stroma occurring 4 years after Intacs implantation. METHODS: A 45-year-old woman underwent bilateral uncomplicated Intacs implantation for myopia. The postoperative course was uneventful. However, between 3 and 4 years after surgery, the patient developed central opacifications of the anterior stroma in both eyes, reducing best spectacle-corrected visual acuity. RESULTS: Intacs were explanted. Confocal microscopy, electron microscopy of the explanted ring segments, and microbiology studies were performed. Opacities were still detectable at the slit-lamp microscope up to 8 months after explantation. CONCLUSIONS: This is the first report on central corneal opacifications after Intacs implantation for myopia. The opacities could be the result of chronic metabolic stress or the beginning of lipid-like changes in another more central corneal localization.

Effect of oral donepezil on intraocular pressure in normotensive Alzheimer patients.

Donepezil, a selective acetylcholinesterase (AChE) inhibitor, has been shown to reduce intraocular pressure (IOP) in ocular normotensive rabbit eyes. The aim of this investigation was to evaluate the effect of oral donepezil on IOP and pupil diameter after mid-term oral treatment in normotensive persons. Thirty-two newly diagnosed Alzheimer patients with normal IOP and no further antiglaucomatous treatment were included in the study. IOP and pupil diameter were evaluated before and 4 weeks after daily intake of 5 mg donepezil. IOP and pupil diameter were significantly lower/smaller after 4 weeks of treatment. The mean IOP of all 63 eyes was 14.1 mmHg before and 12.8 mmHg after treatment (8.8% reduction). Mean pupil diameter constricted from 3.9 to 3.6 mm (-7.4%). These findings show that donepezil, and, possibly, other selective AChE inhibitors, can potentially be used to treat glaucoma. They are also known to have neuroprotective effects in Alzheimer's, and, therefore, might have an additional therapeutic benefit.

Analysis of pseudoprogression after corneal cross-linking in children with progressive keratoconus.

PURPOSE: To analyse the long-term efficacy of corneal cross-linking (CXL) in children with keratoconus and to describe criteria for the detection of pseudoprogression. METHODS: Evaluation of retrospectively collected corneal topography (Placido system) and tomography (Scheimpflug system) results after CXL in children (age 18 or younger). Twenty-five patients (33 eyes) were included. Follow-up was assessed after 1, 2, 3 and 4 years. Progression was defined as an increase in maximal keratometry (Kmax) of at least one dioptre (D) in 1 year. RESULTS: For the entire group, mean Kmax prior to CXL was 55.3 ± 7.3D and decreased significantly (p = 0.00001) after 1 year to 53.4 ± 7.4D. In 23 patients, the progression could be halted. Five cases of presumed progression were identified. One case showed marked steepening in Kmax 4 years after CXL, but the topographic parameters were unchanged. The tomography was repeated and showed that Kmax was stable. Two cases with limbal vernal keratoconjunctivitis (VKC) worsened both in corneal tomography and topography. After resolution of the limbal inflammation, the Kmax values returned to the values before the inflammation. We found two cases of true progression both of which had advanced keratoconus prior to CXL with a preoperative Kmax of 64.4, respectively, 75.1D. CONCLUSION: Our results confirm that CXL is effective in stabilizing keratoconus in children. True progression after CXL could only be verified in two of 33 eyes in a follow-up period of 37.5 months (SD ± 10 months). Two different measuring methods can help to detect diagnostic discrepancies and prevent false conclusions. Moreover, limbal vernal changes can cause transient pseudoprogression, reversible upon sufficient treatment.