[Recanalisation by Probing with a Bicanalicular Silicone Tube (Oggel Silicone Intubation) in Patients with Acquired Lacrimal Stenosis]. / Rekanalisierung durch Sondierung mit Oggel-Sonden-Implantation bei erworbener Tränenwegsstenose.

OBJECTIVES: Recanalisation and bicanalicular splinting with silicone tube is one therapeutic option for acquired lacrimal duct stenosis, and restenosis is frequently achieved. The aim was to determine the therapeutic success of Oggel silicone intubation after lacrimal syringing and probing. We also analysed other characteristics of the complaint and compared the therapeutic success with published results. METHODS: Therapeutic success was defined as subjective absence of complaints. Other complaint features - directly after explantation of the Oggel tube, one month after explantation and one year after explantation - were retrospectively collected by a patient questionnaire, and a questionnaire for the attending ophthalmologist. These were completed with information from the patient's file. We included 82 procedures performed at the Dept. of Ophthalmology, University of Ulm, between 2006 and 2015. Statistical testing of the impact of risk factors on therapeutic success was performed, using logistic regression analysis and the Mann-Whitney U test. Subgroups were compared using Pearson-Chi-square and Fisher's exact tests and a Kaplan-Meier analysis was also performed. RESULTS: Therapeutic success could be documented in 80.8% of patients after explantation of the Oggel tube, in 61.6% of patients after one month and in 42.5% of patients at one year (n = 82). There were no significant differences between the subgroups of stenosis localisation, or the patients' age or sex. There was also no significant influence of the patient's age, the preoperative duration of complaints or risk factors predisposing for lacrimal duct stenosis. For the observation period of one year, the Kaplan-Meier analysis gave a probability of complaint-freeness of 52.2% for the patient group, as well as a mean duration of the complaint-free period of 34.2 weeks. CONCLUSION: The results allow a prognostic assessment of the therapeutic success in the absence of significant differences in the subgroups. The therapeutic success of bicanalicular silicone intubation with the Oggel tube was in the lower third of comparable studies. The results conform to the observation that there is a progressive decline of therapeutic success. The comparison of the literature turned out to be methodically more difficult due to differences in study characteristics. Standardisation would make sense for future studies.

Experimental protocols for ex vivo lens stretching tests to investigate the biomechanics of the human accommodation apparatus.

PURPOSE: To explore alternative experimental protocols to investigate the biomechanical behavior of the crystalline lens and zonules using ex vivo stretching. METHODS: Radial stretching tests were conducted on the anterior segment (consisting of lens, zonules, ciliary body, and sclera) of four pairs of presbyopic human donor eyes. A simple mechanical model is used to describe the behavior of the anterior segment when tested in this way. Each pair of samples was initially stretched with the ciliary body intact. One sample was retested after cutting the ciliary body radially, and the other sample was retested after removing the lens. RESULTS: The external forces needed to stretch the sample with the ciliary body intact were significantly greater than for the tests in which the ciliary body had been cut. The forces measured with the ciliary body intact and lens in situ were comparable to the sum of the forces measured in the tests in which the ciliary body had been cut (lens in situ) and the forces measured in the tests on the intact ciliary body with the lens removed. CONCLUSIONS: When stretching tests are conducted on the anterior segment, significant circumferential tensions develop in the ciliary body. This means that the forces applied to the lens and zonules cannot be related directly to the forces applied by the external loading system. If radial cuts are introduced in the ciliary body prior to testing, however, then this difficulty does not arise.

Elastic properties of human lens zonules as a function of age in presbyopes.

PURPOSE: To investigate the elastic properties of human lens zonules as a function of age in presbyopes. METHODS: We studied 16 presbyopic human donor eyes (ages 47-97). Anterior eye sections with crystalline lens, zonules, ciliary body, and sclera were stretched radially. The stretching device consisted of a chamber filled with balanced salt solution and eight radial hooks to hold the anterior eye section. Radial stretching was created with a stepper motor connected to a digital outside micrometer for linear displacement and digital balance for force measurement. Three eye globes were used to test our methodology. For 13 eye globes, the spring constant, elastic modulus of the zonular system, and Young's modulus of the zonules were calculated. RESULTS: We found linear dependence for force-elongation and force-strain relationships at all ages. In young presbyopic eyes (ages 47-60), the Young's modulus of the zonules was 340 mN/mm(2), whereas in older eyes (ages 83-97) it was significantly lower at 270 mN/mm(2). However, the correlation coefficient between Young's modulus and age (47-97 years) was not significant with P = 0.063. CONCLUSIONS: The zonular system in presbyopic eyes was linear elastic, and the Young's modulus of the zonules decreased 20% from presbyopic age to late presbyopic age. However, there was no significant correlation between Young's modulus and age in presbyopes.

Air-pulse corneal applanation signal curve parameters for the characterisation of keratoconus.

AIMS: To test the use of parameters obtained from the ocular response analyser (ORA) to distinguish between normal and keratoconic eyes, to determine the severity of keratoconus (KC), and to evaluate changes after treatment with cross-linking (CXL) and intrastromal corneal ring (ICR) implantation. METHODS: In total, 42 parameters were derived from the ORA's applanation response curve. Data on 119 subjects were included in the study. We determined the power of discrimination between control subjects (n=48) and KC patients (stages I and II, n=54) using receiver operating characteristic (ROC) curves. We then tested the correlation between all KC stages (n=71) and the ORA parameters. Finally, we evaluated the changes at 4 months after CXL (n=22) and ICR (n=39). RESULTS: The ROC curves for 12 parameters showed excellent results; 24 parameters generated moderate results and six parameters generated poor results. The correlations between the KC stages and 14 parameters were significant, with good to moderate results. The corneal resistance factor and the area under the second peak of the signal curve produced the best results in distinguishing between normal and KC eyes. Two parameters after CXL (p2area and time1) and six parameters after ICR implantation (aplhf, uslope11, w11, path11, time1 and deltatime) showed significant differences with respect to the preoperative conditions. CONCLUSION: Most of the new waveform parameters demonstrated good ability to distinguish between KC and normal eyes. The changes in the parameter values after CXL and ICR treatments were smaller than expected.