Retinal toxicity of triamcinolone’s vehicle (benzyl alcohol): an electrophysiologic and electron microscopic study

Purpose To assess retinal toxicity of the vehicle of triamcinolone, benzyl alcohol (BA), when injected into the vitreous cavity of rabbits. Methods This prospective comparative experimental study included 24 pigmented rabbits assigned into two groups: group 1 (experimental, n = 12) received intravitreal 0.1 ml of BA, and group 2 (control, n = 12) received intravitreal 0.1 ml of balanced salt solution (BSS); all injections were done in the right eyes. Clinical examinations [slit lamp biomicroscopy, indirect ophthalmoloscopy, and three intraocular pressure (IOP) measurements] were done on both eyes before injection, at 1 and 3 h post injection, together with electroretinograms (ERGs) at 3 days, 1, 2, 4, and 6 weeks following injections. Three rabbits from each group were euthanased at 1, 2, 4, or 6 weeks and eyes were sent for light and electron microscopic examination for quantitative morphometric measurements. Results The mean amplitudes of the a and b waves of the BA-injected eyes were 6.42 ± 9.02 μv and 11.18 ± 15.18 μv at 3 days, respectively, which were significantly reduced compared with the BSS-injected eyes (30.87 ± 8.22 μv and 57.90 ± 13.38 μv, respectively; P < 0.01 t-test) and the non-injected contralateral eyes (36.20 ± 7.85 μv and 64.10 ± 9.36 μv, respectively; P < 0.01 t-test). These ERG responses continued to be significantly reduced in the BA-injected eyes (P < 0.01 t-test) throughout the study period. The mean ganglion cell count was significantly reduced (P < 0.005 t-test) in the BA-injected eyes (8.42 ± 2.4) compared with the BSS- and non-injected eyes (16.42 ± 3.9 and 16.5 ± 4.2, respectively). The mean thicknesses of the inner nuclear layer (INL) and outer nuclear layer (ONL) were significantly reduced (P < 0.005 t-test) in the BA-injected eyes (3.78 ± 0.96 μm and 11.77 ± 1.29 μm, respectively) compared with the BSS- (6.1 ± 0.92 μm and 21.82 ± 0.95 μm, respectively) and non-injected eyes (7.05 ± 1.9 μm and 22.49 ± 1.01 μm, respectively). Electron microscopy showed moderate to severe intracellular changes in the ganglion cell layer, INL, ONL, and photoreceptor layer at 6 weeks in BA-injected eyes, with no significant changes in BSS-injected eye. There was no significant rise in the IOP or clinical evidence of increased lens density during the study period in any of the eyes. Conclusions Triamcinolone acetonide’s vehicle, BA, produced severe ERG and structural damage to the retina when injected intravitreally.     

Mesenchymal stem cell transplantation in a rabbit corneal alkali burn model: engraftment and involvement in wound healing

PURPOSE: To investigate whether systemically transplanted mesenchymal stem cells (MSCs) can home and engraft in tissue to promote cornea wound healing after alkali burn, as a new source for treatment. METHODS: Corneal alkali burn was created in four group rabbits: Group I, normal bone marrow function, without MSCs transplantation; Group II, normal bone marrow function, with MSCs transplantation; Group III, bone marrow suppressed by cyclophosphamide, without MSCs; Group IV, bone marrow suppressed by cyclophosphamide, with MSCs. Clinical outcome was evaluated by cornea re-epithelization, cornea opacity, and neovascularization. Cell engraftment into bone marrow, circulation, and cornea was monitored. Immunohistochemistry, using proliferating cell nuclear antigen (PCNA), P63, vimentin, and alpha-smooth muscle actin (alpha-SMA) was carried out to assess the cell proliferative and differentiative ability. RESULTS: At the time of 1-month follow-up, Group II rabbits showed the best clinical results with a clearer healed cornea compared with other groups. Well-formed neovascularization appeared on day 14 after alkali burn in Group II, that coincided with the maximum engraftment of MSCs. PCNA, P63, vimentin were more strongly expressed in Group II at multiple time points. DiI-labelled MSCs were differentiated into myofibroblast by the expression of alpha-SMA. Delayed and insufficient cell engraftment, with malformed neovascularization and retarded corneal wound healing was found in Groups III and IV. CONCLUSIONS: Systemically transplanted MSCs can engraft to injured cornea to promote wound healing, by differentiation, proliferation, and synergizing with haemotopoietic stem cells.     

Tear fluid concentration of mmp–8 is elevated in non—allergic eosinophilic conjunctivitis and correlates with conjunctival inflammatory cell infiltration

Background  To investigate tear fluid concentration of matrix metalloproteinase 8 (MMP–8) and its relation to conjunctival inflammatory cell infiltration in persistent non—allergic eosinophilic conjunctivitis (NAEC). Methods  Two groups were included: 26 consecutive adult patients with NAEC (conjunctival eosinophils at least 1+ [1-10 eosinophils/slide], skin prick test [SPT] to common allergens negative), and 26 asymptomatic adult persons (no conjunctival eosinophils, SPT negative). MMP–8 tear fluid concentrations were determined by immunofluorometric assay, and conjunctival brush cytology samples from NAEC patients were used for MMP–8 immunocytochemistry. Gelatin zymography was used to illustrate proteolytic activity within the tear fluid samples. Results  The mean MMP–8 concentration was significantly higher among NAEC patients (214.3 ± 327.7 μg/l) than among healthy persons (50.4 ± 62.3 μg/l, P < 0.0001). In the NAEC patients, tear fluid MMP–8 correlated with the numbers of conjunctival neutrophils (r = 0.66, P = 0.0002) as well as with goblet cells and columnar epithelial cells (r = 0.54 for both, P = 0.045), but not with the lymphocyte numbers (r = -0.36, P = 0.0741). By immunocytology, MMP–8 protein could also be detected in vivo in the inflammatory cell population within the conjunctiva. Zymography revealed that proteolysis was significantly higher in the NAEC group, and activated enzymes were practically found only in the NAEC group. Conclusions  The results showed that NAEC is an inflammatory condition characterized by increased tear fluid MMP–8 levels, probably derived from both inflammatory and structural conjunctival cells. The increased proteolytic activity in NAEC patients may indicate risk of conjunctival structural changes (remodeling).     

Central corneal thickness and Diaton transpalpebral tonometry

Background To examine the effects of central corneal thickness on the measures obtained from transpalpebral tonometry (Diaton), and to identify correlations between intraocular pressure (IOP) measurements with Diaton and the Goldmann applanation tonometer (GAT). Methods In this cross-sectional study, 162 eyes of 81 participants were included. Intraocular pressure measurements were obtained in all patients using Diaton and GAT. Central corneal thickness was determined by ultrasound pachymetry. The participants were stratified by corneal thickness: group I <530 μm (n = 56), group II 530–560 μm (n = 65), and group III >560 μm (n = 41). Results There were moderate correlations between IOP readings obtained using the Diaton and corrected GAT (C-GAT) (r = 0.303; P < 0.0001), and between corrected Diaton (C-Diaton), and C-GAT (r = 0.399; P < 0.0001). The mean Diaton tonometer readings were lower than C-GAT measurements (Diaton-corrected GAT mean difference, 0.9 ± 3.8 mmHg; c-Diaton-corrected GAT mean difference, 0.7 ± 3.5 mmHg). Differences were detected between the groups of patients for the GAT values [2.4 ± 3.6 mmHg for those with the thinnest corneas (<530 μm), 0.7 ± 3.6 mmHg for those with moderate corneas (between 531 μm and 560 μm), and −0.6 ± 3.6 mmHg for those with the thickest (>560 μm) corneas], whereas a significantly lower difference (0.9 ± 3.8 mmHg) was noted for the Diaton values of all individuals. Conclusions The Diaton measurements show moderate correlation with those provided by applanation tonometry. The Diaton tonometer seems to be more affected by the corneal thickness, especially in the thinnest corneas. No author has a financial interest in any product mentioned in the article. No author has a conflict of interest in any product mentioned in the article.     

Central corneal thickness in adult Chinese. Association with ocular and general parameters. The Beijing Eye Study

Background To evaluate the distribution of central corneal thickness and its associations in the adult Chinese population. Methods The Beijing Eye Study 2006 is a population-based study including 3,251 (73.3%) subjects (aged 45+ years) out of 4,439 subjects who participated in the survey in 2001 and who returned for re-examination. Central corneal thickness (CCT) measurements were performed by slit lamp-based optical coherence tomography. Results Central corneal thickness measurement data were available for 3,100 (95.4%) subjects. Mean CCT was 556.2±33.1 μm (median: 553 μm; range: 429–688 μm). In multiple regression analysis, CCT was significantly associated with optic disc area (P = 0.043), urban region (P < 0.001; odds ratio (OR): 4.77; 95% confidence interval (CI): 2.37, 7.17), male gender (P < 0.001; OR: 5.64; 95%CI: 2.57, 8.71), and intraocular pressure measurements (P < 0.001). It was not significantly associated with body weight (P = 0.54) and body height (P = 0.66), age (P = 0.17), and refractive error (P = 0.43). Intraocular pressure (measured by pneumotonometry) increased for each μm central corneal thickness increase by 0.03 mmHg. Conclusions In the adult Chinese population, CCT was significantly associated optic disc area, urban region, and male gender. Intraocular pneumotonometric pressure measurements increased for each μm increase in central corneal thickness by 0.03 mmHg. CCT was not associated with age and refractive error. Supported by Beijing Natural Science Foundation No 7071003, Beijing, China.     

Comparison of ultrasonic pachymetry with orbscan in corneal haze

Background To compare the results of ultrasonic and Orbscan pachymetry in corneal haze not related to surgery. Methods An institutionally based, prospective, controlled clinical trial included 40 eyes of 40 consecutive patients with corneal haze not related to surgery. Fifty normal eyes were used as a control group to calculate the customized acoustic factor. Corneal haze was graded with slit-lamp by a single examiner. Ultrasonic and Orbscan II pachymetry measurements were obtained. Paired t- and Kruskal-Wallis tests were used to evaluate the difference between ultrasonic and Orbscan pachymetry measurements. Correlation of the two methods and haze grade were determined with Kendall’s tau-b correlation analysis. Results Eighty-five percent of patients had moderate haze. With the customized acoustic factor, Orbscan values were significantly smaller than ultrasonic pachymetry measurements (p = 0.001, paired samplet-test). Increased haze grade resulted in smaller Orbscan pachymetry measurements however, this difference was insignificant (p = 0.444, Kruskal-Wallis test). A positive correlation was found between two methods, though insignificant (p = 0.064, Kendall’s tau-b correlation). When grouped in respect of diagnoses, differences in pachymetry measurements as well as the correlation were not significant (p > 0.05). Conclusion An insignificant positive correlation was found between the two methods in the presence of corneal haze. Orbscan measurements were inversely related to haze grading, and were significantly lower than ultrasonic pachymetry. According to our results, we recommend that clinicians should not count on Orbscan topography alone in the presence of corneal haze. Financial support was obtained from Baskent University, Ankara, Turkey [project # KA05/207] This study is registered at ClinicalTrials.gov with the registration ID# NCT00439114. None of the authors has any proprietary or financial interest in any product or device used in this study.     

Slowing the degenerative process, long lasting effect of hyperbaric oxygen therapy in retinitis pigmentosa

Background Retinitis pigmentosa (RP) therapy is still an unsolved challenge. Recent reports have underlined that hyperbaric oxygen (HBO) therapy could play a role in slowing the retinal degenerative process. The aim of this study was to assess the efficacy of HBO therapy on visual function in RP patients. Methods We performed a single-center, comparative, longitudinal case-controlled randomized clinical trial, which lasted 10 years. We randomly divided RP patients into two groups. Group 1, the control group, consisted of 44 RP patients (21 males and 23 females; mean age 35.5) who took Vitamin A. Group 2, with 44 RP patients (21 males and 23 females; mean age 35,02), underwent HBO therapy. No statistically significant difference was found at the beginning of the study between the two groups. We compared the results concerning visual acuity, Goldmann perimetry, static perimetry Humphrey field analyzer (HFA), and electroretinogram (ERG) obtained in the two groups at 5 and 10 years follow-up. Statistical analysis was performed with Kaplan-Meier life-table with the evaluation of log-rank coefficient. Results At 5 year follow-up, 87.5% of group 2 patients preserved 80% of the initial visual acuity, while the same result was achieved in only 70.4% of group 1 patients (X² = 8.2; p < 0.01); at 10 year follow-up, 63.33% of group 2 patients preserved 80% of the initial visual acuity, while the same percentage of residual visual acuity was maintained in 40% of group 1 patients (X² = 3.22; p = 0.05). At 10 year follow-up, Goldmann perimetry (target I4e) did not change in 31.6% of group 2 and in 10.5% of group 1; evaluation of mean defect (MD) with static perimetry HFA showed that 53% of HBO patients had 80% of residual mean sensitivity compared to 23.5% of the control group patients (X² = 4.72; p = 0.035). ERG b-wave mean values at the end of the protocol were significantly higher in the HBO treated group (X² = 4.53; p = 0.013). Conclusion Our study underlines that HBO therapy can be a safe alternative approach to RP patients, contributing to the stabilization of their visual function concerning visual acuity, visual field, and ERG responses while waiting for a definite cure.     

Effect of intravitreal plasmin on vitreous removal through a 25-gauge cutting system in the rabbit in vivo

Purpose  Intravitreal plasmin creates a posterior vitreous detachment, but may also liquefy the vitreous. This study measures the rate of vitreous removal from rabbit eyes after plasmin injection in vivo. Methods  Intravitreal injections of 150 IU hyaluronidase (n = 5), 0.5 activity units (AU, n = 6) or 0.9 AU of streptokinase-activated human plasmin (n = four groups of 6) in 0.1 ml were performed in rabbits, the fellow eyes received 0.1 ml BSS. After 30 min (hyaluronidase), 30 min, 4 h, 12 h or 24 h (0.9 AU plasmin) or 24 h (0.5 AU plasmin), 1 ml of vitreous was removed from each eye without infusion, using a 25-gauge cutter and a standardized protocol. Animals were sacrificed after surgery. Results  Compared to fellow eyes, the average rate of vitreous removal was increased by hyaluronidase by 68.9 ± 6.3% (p < 0.05) and by 0.5 AU plasmin (24 h) by 26.8 ± 3.3% (p < 0.05). 0.9 AU of plasmin increased removal rates by 0.8 ± 10% (n.s.), 15.4 ± 6.3% (p < 0.05), 40.3 ± 3.1% (p < 0.05), and 71.9 ± 32.4% (p < 0.05) after 30 min, 4 h, 12 h and 24 h incubation respectively. The ratios of removal rates of treated/control eyes in the 0.9 AU groups showed a linear correlation with incubation time (r = 0.783, p < 0.0001). Conclusion  Intravitreal plasmin increases the rate of vitreous removal in rabbits. This work was presented in part at the 76th Annual Meeting of the Association for Research in Vision and Ophthalmology, 2004. Supported in part by grants from the University of Aachen, Germany and the Deutsche Forschungsgemeinschaft (HE 3503/1-1) to M. Hermel, and by NuVue Technologies, Keene, New Hampshire, USA. W. Dailey and M. Hartzer have a proprietary interest in plasmin.     

Optic nerve head topography in nonglaucomatous, normotensive patients with unilateral exfoliation syndrome

Background  Optic nerve head damage may result from high intraocular pressure (IOP) associated with the exfoliation syndrome (EXS). At equal IOP levels, eyes with EXS may suffer damage more easily than eyes without EXS. Opinion differs as to whether EXS alone, without the contributory effect of a raised IOP, is a risk factor for optic nerve head damage. Methods  36 nonglaucomatous, normotensive patients (mean age 68.4 ± 7.1 years) with unilateral EXS were examined for optic disc topography with confocal scanning laser ophthalmoscopy (the Heidelberg Retina Tomograph). The only patients included were those with an IOP difference of ≤3 mmHg between fellow eyes and with IOP fluctuation ≤5 mmHg in diurnal curves. Results  Mean IOP was higher in the EXS than in the fellow non-EXS eyes (15.0 ± 2.8 vs 14.1 ± 2.7 mmHg, P < 0.001). According to the multivariate analysis of variance, no differences existed in the global parameters between EXS and non-EXS eyes (P = 0.778). Nor did differences appear in sectoral parameters between fellow eyes in the temporal (P = 0.634), temporal superior (P = 0.236), temporal inferior (P = 0.330), nasal (P = 0.711), nasal superior (P = 0.307), and nasal inferior (P = 0.434) sectors. Conclusion  EXS may not in itself be a risk factor for optic disc damage when IOP is not elevated from its base level, and when its variation is normal. The authors have no proprietary or financial relationship with any instrument, method, or organization mentioned herein. The authors have full control of all primary data and agree to allow Graefe’s Archive for Clinical and Experimental Ophthalmology to review the data upon request.     

Selective thrombophilia screening of patients with nonarteritic anterior ischemic optic neuropathy

Background  To date, the question whether there is a relationship between thrombophilic disorders and the development of nonarteritic ischemic optic neuropathy (NAION) remains controversial. We sought to investigate the prevalence of various coagulation defects among NAION patients <65 years of age, and to provide clinical guidelines for a selective thrombophilia screening. Methods  A cohort of 35 patients <65 years of age with NAION and 70 controls matched for age and sex were prospectively screened for thrombophilic risk factors. Results  Overall, thrombophilic defects were found to be present in 18 of 35 patients (51.4%) and in 12 of 70 (17.1%) controls (P = 0.0005). The most frequent coagulation disorders were increased levels of factor VIII (P = 0.015) and lipoprotein (a) (P = 0.005). Patients without cardiovascular risk factors had a statistically significant higher frequency of coagulation disorders than patients with these risk factors (P = 0.0059). There was a strong association of coagulation disorders and a personal or family history of thromboembolism (P = 0.028). Moreover, we determined the age of ≤55 years at the time of the first thromboembolic event or NAION as a strong predictor of underlying thrombophilia (P = 0.0002). Conclusions  Our results indicate that thrombophilic disorders are associated with the development of NAION in specific subgroups of patients. Selective screening of young patients, subjects with a personal or family history of thromboembolism, and patients without cardiovascular risk factors may be helpful in identifying NAION patients with thrombophilic defects. None of the authors has a proprietary or financial interest in any product mentioned. The corresponding author has full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.     

Long axial length as risk factor for normal tension glaucoma

Background  The high prevalence of normal tension glaucoma (NTG) in the Japanese requires special screening tests other than measurements of only the intraocular pressure (IOP). This study was carried out to determine whether there is a significant association between the axial length of the eye and the presence of NTG. Methods  We reviewed the medical records of all patients who were scheduled to undergo cataract surgery alone or combined with glaucoma surgery at the same time. There were 87 patients with NTG, 137 with POAG, and 978 non-glaucomatous control cases. The axial length, IOP, curvature of the anterior corneal surface, age, and gender were determined at the time of the operation. If both eyes had surgery, data from only the right eyes were analyzed. An association of these parameters with NTG and POAG was analyzed by logistic regression analysis. The three groups were analyzed for differences in the axial length using the Kruskal-Wallis test followed by the Mann-Whitney U test. Results  The axial length was significantly associated with NTG (odds = 1.24, P = 0.002) and POAG (odds = 1.28, P = 0.001). The incidence of either POAG or NTG was significantly higher in patients with axial lengths ≥25.0 mm (odds = 2.29, P < 0.001, Fisher’s exact test). The age at the time of cataract surgery was weakly but significantly correlated negatively with the axial length (r = −0.24, P < 0.001, Pearson’s correlation coefficient test). Men had significantly longer axial lengths than women. Conclusions  Long axial lengths can be considered a risk factor for NTG and POAG, and patients with long axial lengths need to be carefully examined for glaucoma.     

Comparison of central corneal thickness and anterior chamber depth measurements using three imaging technologies in normal eyes and after phakic intraocular lens implantation

Background  The repeatability and interchangeability of imaging devices measuring central corneal thickness (CCT) and anterior chamber depth (ACD) are important in the assessment of patients considering refractive surgery. The purpose of this study was to investigate the agreement of CCT and ACD measurements using three imaging technologies in healthy eyes and in eyes after phakic intraocular lens implantation (pIOL). Methods  In this comparative study, CCT and ACD were measured using anterior segment optical coherence tomography (AS-OCT), Orbscan II, and Pentacam in 33 healthy volunteers (66 eyes) and 22 patients (42 eyes) after pIOL implantation. Intraobserver repeatability was evaluated for all three devices in the healthy volunteer group. Results  Pairwise comparison of CCT measurements showed significant differences between all devices (P < 0.001), except for the AS-OCT and Orbscan II in the healthy volunteer group (P = 0.422) and the Orbscan II and Pentacam in the pIOL group (P = 0.214). ACD measurements demonstrated significant differences between all pairwise comparisons in both groups (P ≤ 0.001). Intraobserver reliability was high for CCT and ACD measurements in the healthy volunteer group, with coefficients of variation ranging from 0.6% to 1.2% and 0.4% to 0.5% respectively. Conclusions  CCT and ACD measurements using AS-OCT, Orbscan II, and Pentacam demonstrated high intraobserver reliability. However, these devices should not be used interchangeably for measurements of CCT and ACD in healthy subject and patients after pIOL implantation. Financial support  None The authors have no financial or proprietary interest in any aspect of this study and have full control of all primary data, and agree to allow Graefe’s Archive for Clinical and Experimental Ophthalmology to review our data if requested.     

Anti-inflammatory effect of angiotensin type 1 receptor antagonist on endotoxin-induced uveitis in rats

Background Angiotensin II type 1 (AT1) receptor-antagonists are widely used for treatment of hypertension. Recent studies have demonstrated a protective effect of renin angiotensin system (RAS) antagonism against immune-mediated inflammatory diseases such as myocarditis, chronic allograft rejection, antiglomerular basement membrane nephritis, colitis, and arthritis. However, only a few reports have demonstrated the effect of RAS in ocular inflammatory conditions. The purpose of this study was to investigate the anti-inflammatory effect of a selective AT1 receptor antagonist, losartan, on endotoxin-induced uveitis (EIU) and compare the effect on experimental autoimmune uveoretinitis (EAU). Methods To induce EIU, 7-week-old Lewis rats were injected subcutaneously with 200 μg lipopolysaccharide (LPS). Losartan was administered intravenously at the same time. The aqueous humor was collected from eyes 24 h after LPS injection. The number of infiltrating cells, protein concentration, and levels of tumor necrosis factor (TNF)-α and monocyte chemoattractant protein-1 (MCP-1) in the aqueous humor were determined. The collected eyes were immunohistochemically stained with monoclonal antibody for activated nuclear factor (NF)-κB. To induce EAU, C57BL/6 mice (6–8 weeks old) were immunized with human interphotoreceptor retinoid binding protein (hIRBP)-derived peptide emulsified in complete Freund’s adjuvant (CFA) and concomitantly injected with purified Bordetella pertussis toxin (PTX). Clinical severity of EAU and T cell proliferative response were analyzed. Results Losartan significantly suppressed the development of EIU. Numbers of aqueous cells of control EIU rats, those from EIU rats treated with 1 or 10 mg/kg of losratan were 75.3 ± 45.6 × 10⁵, 27.9 ± 8.1 × 10⁵, or 41.3 ± 30.9 × 10⁵ cells/ml respectively (p < 0.01 vs control). Aqueous protein, TNF-α, and MCP-1 levels were also significantly decreased in a manner dependent on the amount of losartan administered (p < 0.01). Treatment of EIU rats with losartan suppressed activation of NF-κB at the iris ciliary body. Thus, the suppressive effect of losartan on ocular inflammation in EIU appeared to result from down-regulation of NF-κB activation and reduction of inflammatory cytokine production. On the other hand, in the EAU model, neither the clinical score nor the antigen-specific T cell proliferative response was significantly influenced by the treatment with losartan. Conclusions The present findings indicate that RAS may be involved in the acute inflammation of the eye, but not in T cell-dependent ocular autoimmunity. Antagonism of the RAS may be a potential prophylactic strategy for treatment of the human acute ocular inflammation.     

Online optical coherence pachymetry to evaluate intraoperative ablation parameters in LASIK

Purpose The ablation of corneal tissue with the excimer laser can be variable and can lead to miscorrections. The purpose of this study was to evaluate intraoperative ablation parameters during laser-assisted in-situ keratomileusis (LASIK) with online optical coherence pachymetry (OCP). Methods In a prospective, nonrandomized, comparative clinical study, the ablation parameters were continuously assessed intraoperatively with online OCP (Heidelberg Engineering, Lübeck, Germany) in 45 myopic and 10 hyperopic LASIK treatments. The central intraoperative ablation values were compared with the calculated values of the excimer laser (ESIRIS, Schwind, Germany) and the postoperative refraction. The ablation process and the ablation rate in μm per layer, time, and dioptric correction were evaluated in myopic corrections. Results In myopic LASIK treatments, a linear ablation process was measured with a mean correlation coefficient of −0.968 ± 0.04. The intraoperative ablation rate was, on average, 0.59 ± 0.17 μm per layer, 1.45 ± 0.48 μm per second, and 24.63 ± 7.81 μm per corrected diopter. These values were 28.7% to 29.6% higher (P < 0.001) than the calculated values. There was a significant correlation (P < 0.001) for the ablation rate per layer (r = 0.823), per second (r = 0.869), and corrected diopter (r = 0.892), but no correlation (r = 0.21, P = 0.239) between the measured linear ablation process and the postoperative refraction. During hyperopic LASIK treatments, without ablation of the corneal center, there was a significant decrease (P = 0.005) of the stromal thickness by 18.34 ± 14.13 μm, which corresponded to a mean corneal dehydration rate of 0.27 μm per second. Conclusions Online OCP allowed a clinical evaluation of intraoperative ablation parameters in LASIK. Further studies are needed to assess a possible active control of the excimer laser ablation from these continuous values, which could possibly improve current ablation nomograms. Presented at the annual meeting of the Deutsche Ophthalmologische Gesellschaft in Berlin, Germany, September 2005. The authors have no commercial, proprietary, or financial interest in any research or devices described in the presented study.     

The consequences of delayed intervention when treating chemical eye burns

Background Immediate rescue intervention for chemical and thermal eye burns can save the victim’s sight. We studied the anterior chamber pH changes immediately after ex vivo eye burn to investigate the effects of immediate and delayed intervention. Methods Twenty three enucleated pigs eyes were burnt with 500 μl 2 mol NaOH for 20 s using a cylinder with a diameter of 10 mm. The corneas were rinsed in groups with 1015 ml ordinary tap water at a flow rate of 1.125 ml/s for 15 minutes immediately after burning (n = 6), and after a delay of 20, 40, and 60 s (n = 5, 3 and 4 respectively). One group of eyes was not rinsed (n = 5). The intraocular pH was defined at the start as ‘min pH’ and the end as ‘max pH’(ΔpH = max pH-min pH). Results The intraocular pH increased sharply in the untreated eyes from a min pH of 6.76 ± 0.55 to a max pH of 11.85 ± 0.24, yielding a ΔpH of 5.08. The difference between the timepoint at which the pH began to increase and the speed of change was significantly different between the unrinsed and rinsed eyes, and there was an inverse correlation between this and the time at which rinsing started (p < 0.001). The best results were achieved in eyes rinsed immediately after burning (p < 0.001). The pH in the eyes not rinsed immediately increased rapidly, and in all groups in which rinsing was delayed the max pH was markedly higher (p = 0.093). Conclusions Immediate emergency rinsing is essential in eye burn victims. Appropriate rinsing solutions and treatment facilities in the form of rinsing stations where chemical burns may occur must be available at the workplace. Tap water is also effective as a rinsing solution. Presentation The results were the subject of a short oral presentation at the 104th DOG Annual Meeting 2006 in Berlin.     

The Effect of Octreotide Against Oxidative Damage in Photosensitized Conjunctiva and Cornea of Rabbits

The purpose of this study was to determine the protective effect of octreotide against oxidative damage in rabbit conjunctiva and cornea exposed to ultraviolet radiation. Twenty rabbits weighing 2500–3000 g were used and we divided them into 4 groups with randomly selected 5 rabbits. Rabbits were exposed to 2 J/cm²/h of ultraviolet A radiation (UVA) in the range 320–405 nm for 12 h per day for 90 days. Group 1 did not receive any treatment or UVA exposure (control group). Group 2 was only exposed to UVA radiation (UVA group). Group 3 received 8-methoxypsoralen and UVA (PUVA group). Group 4 was treated with 8-methoxypsoralen + UVA + octreotide (octreotide group). At the end of 90 days the rabbits were killed by decapitation and then eyes were enucleated. Both eyes of each rabbit were used for histopathologic evaluation. Histopathologic analysis of each group indicated that UVA group and PUVA group showed increasing edema (p<0.01), inflammation (p<0.05), fibroblast proliferation (p<0.05), dysplasia (p<0.05), hyperchromasia (p<0.01) in the conjunctiva. Octreotide group had significant protective effect in comparison with the UVA group and PUVA group. The UVA group and PUVA group showed increasing proliferation (p<0.01), dysplasia (p<0.01), hyperchromasia (p<0.01), pyknosis (p<0.001) and parakeratosis (p<0.01) in the corneal epithelium. Octreotide group showed similar results with control group. We conclude that octreotide which is considered as free radical scavenger protects the eye from the damaging effect of UV exposure.     

Retinopathy and mortality. The Beijing Eye Study

Background To assess the association between a retinopathy as defined by the Early Treatment of Diabetic Retinopathy Study (ETDRS) criteria, and mortality in a population-based setting. Methods At baseline in 2001, the Beijing Eye Study examined 4,391 subjects for retinopathy lesions, with a detected frequency of 285/4391 (6.5%) subjects. Using fundus photographs, the retinopathy was graded according to the Early Treatment of Diabetic Retinopathy Study (ETDRS) criteria. The mean age was 56.05 ± 10.51 years (range, 40–101 years). In 2006, all study participants were re-invited for a follow-up examination. Results Out of the 4,391 subjects, 3,224 subjects (73.4%) returned for follow-up examination, while 140 subjects (3.2%) were dead and 1,027 subjects (23.4%) did not agree to be re-examined or had moved away. Mortality rate was significantly higher (P = 0.002; odds ratio [OR]: 2.20; 95% confidence intervals [CI]: 1.32, 3.67) in the 285 subjects with retinopathy (18/285 or 6.3 ± 1.4%; 95%CI: 3.6%, 9.0%) than in the 4,106 participants without retinopathy (122/4,106 or 3.0 ± 0.3% 95%CI: 2.4%, 3.6%). In binary logistic regression analysis, mortality was significantly associated with age (P < 0.001; OR: 1.10; 95%CI: 1.08, 1.12), gender (P = 0.006; OR: 0.61; 95%CI: 0.43, 0.86), rural versus urban region (P < 0.001; OR: 5.65; 95%CI: 3.81, 8.40), and presence of retinopathy (P = 0.005; OR: 2.13; 95%CI: 1.25, 3.62). Conclusions In addition to higher age, male gender, and living in a rural region, a retinopathy as defined by ETDRS criteria is a risk factor for an increased mortality in adult Chinese.     

Cataract and mortality. The Beijing eye study

Background To assess an association between cataract and mortality in a population-based setting. Methods At baseline in 2001, the Beijing Eye Study examined 4255 subjects for cataract using standardized lens photographs which were examined according to the Age-Related Eye Disease Study scheme. In 2006, all study participants were re-invited for a follow-up examination. Results Out of the 4255 subjects, 3142 subjects (73.8%) returned for follow-up examination, while 135 subjects (3.2%) were dead and 978 subjects (23.0%) did not agree to be re-examined or had moved away. In multivariate analysis, the amount subcapsular cataract was significantly associated with increased mortality (P = 0.029; OR: 2.14; 95%CI: 1.08, 4.25), particularly for the subjects with an age of 65+ years and 70+ years (P = 0.016 and P = 0.003 respectively). Correspondingly, product of age times amount of subcapsular cataract was significantly associated with mortality (P = 0.001). Degree of nuclear cataract and amount of cortical cataract were not associated with mortality in multivariate analysis (P = 0.910 and P = 0.938 respectively). Conclusions As also found in previous epidemiological studies on Western populations, cataract, namely subcapsular cataract in elderly subjects, is associated with an increased mortality risk.     

Comparative evaluation of vitrectomy and dye-enhanced ILM peel with grid laser in diffuse diabetic macular edema

Background The purpose of this study is to compare the effectiveness of pars plana vitrectomy (PPV) and dye-enhanced peeling of the internal limiting membrane (ILM) with modified grid laser photocoagulation in patients with diffuse diabetic macular edema and to determine if any correlation exists between improvement in visual acuity (functional improvement) and reduction in foveal thickness and macular volume (anatomical improvement). Design This is a randomized, prospective, comparative, interventional study. Method In this study 24 eyes of 24 patients with metabolically stable diabetes and with diffuse diabetic macular edema were evaluated. The patients were randomized to either pars plana vitrectomy with removal of ILM which was done in 12 eyes (ILM group) and modified grid laser photocoagulation carried out in the remaining 12 eyes (laser group). Main outcome measures were (1) the postoperative visual acuity in the form of ETDRS log MAR values, (2) foveal thickness and (3) macular volume as measured by optical coherence tomography. The correlation between improvement in visual acuity and the reduction of foveal thickness and macular volume in both the groups were also evaluated. The results were all subjected to statistical analysis. Results The ETDRS log MAR visual acuity difference between the two groups at the end of 6 months was not clinically significant (P = 0.525). However, foveal thickness and macular volume decreased significantly more in the ILM group compared to the laser group (P = 0.001, P < 0.001, Mann Whitney U test). There was no correlation between the improvement in visual acuity and the reduction of foveal thickness (r = −0.158, P = 0.6) (ILM group), r = −0.155, P = 0.7) (laser group) in both groups. Conclusions PPV with ILM peeling was shown to be beneficial by inducing a statistically significant reduction of macular thickness and macular volume. Visual acuity also demonstrated a trend towards improvement in both the ILM peel group and the grid laser group; however, the comparative VA outcome analysis between the two groups was not significantly different. Besides, there was also no correlation between the reductions of foveal thickness and macular volume with the improvement in visual acuity in either of the groups.     

白内障超声乳化术对泪膜功能的影响

目的：观察白内障超声乳化吸除联合人工晶状体植入手术对于患者术后泪膜的影响,探讨其临床意义。
　　方法：随机选取接受超声乳化白内障吸除术治疗的患者106例140眼,观察患者术前;术后1 d;1,2,3 wk;1 mo这六个时间节点的主观干燥异物感,通过角膜荧光素试验(FSC)、基础泪液分泌试验(SⅠt)和泪膜破裂时间(BUT)这三个指标测定患者的泪膜功能变化,并分析泪膜稳定性和角膜知觉之间的相关性。
　　结果：患眼术后1d;1,2wk干眼症状累计得分高于术前( t=8.53, P=0.000;t=6.27, P=0.000;t=9.02, P=0.000),患眼术后3 wk和1 mo干眼症状累计得分与术前相比无差异(t=1.91,P=0.824;t=1.27,P=0.069)。患眼术后1d;1,2wk角膜上皮荧光素染色点与术前相比增多(t=11.64, P=0.000;t=9.61,P=0.000;t=8.87,P=0.001),患眼术后3 wk和1 mo角膜上皮荧光素染色点与术前相比无差异(t=2.52, P=0.746;t=1.16,P=0.094)。患眼术后1d;1,2wk角膜知觉检测数值明显大于术前( t=9.61,P=0.000;t=9.27,P=0.000;t=11.39,P=0.024),术后3wk和1mo角膜知觉检测结果数值与术前相比无差异( t=1.19, P=0.562;t=2.17,P=0.501)。
　　结论：白内障超声乳化吸除联合人工晶状体植入术会在短期内降低术眼泪膜的稳定性,但是在长期休养之后会得到一定程度上的改善。