Isaak Fischinger

Uniaxial tensile testing and atomic force microscopy (AFM) nanoindentation experiments are two valuable methods used to quantify changes in stiffness after corneal crosslinking (CXL). Here, we apply these methods by characterizing corneal stiffness ex vivo before and after CXL. Sixty-two fresh porcine corneas were divided into three groups: an untreated control group, a CXL3 group treated with the Dresden protocol, and a CXL9 group treated with the accelerated protocol. Biomechanical testing was then performed using either uniaxial tensile testing or AFM nanoindentation. Uniaxial tensile testing revealed a significant increase in corneal stiffness for the CXL3 group compared to the control group (p < 0.05). At 10% strain, the CXL3 and CXL9 groups exhibited increases in stiffness of 96% and 48%, respectively, compared to the control group. In contrast, AFM analysis revealed no significant differences in stiffness, showing 28% and 16% increases in the CXL3 and CXL9 groups, respectively, compared to the control group. The results suggest that uniaxial tensile testing provides a robust, sample-averaged measure of global stiffening. Interestingly, AFM nanoindentation enables mapping of localized biomechanical changes with high spatial resolution but is less sensitive to overall biomechanical changes induced by CXL.

Introduction Ocular sticks are used to absorb fluids during ophthalmic surgeries. Hence, this prospective study was conducted to evaluate the clinical performance, safety, and usability of Pro-optha^® Ocular Sticks in comparison to an alternative device under the conditions of routine ophthalmic surgeries. Methods Patients requiring eye surgery were randomly allocated into two equal groups, with the investigational device, Pro-ophta^® Ocular Sticks, as the intervention group (IG) and the alternative stick as the comparator group (CG). Two types of surgery were performed. The study is also registered on the German Clinical Trials Register with ID DRKS00025690. Results 106 patients were included in the analyses. In both treatment groups, the investigator’s/surgeon’s general user satisfaction was rated as either “good” or “very good.” The non-inferiority hypothesis that the Pro-ophta^® Ocular Stick is not rated worse in satisfaction than the alternative device was confirmed with statistical significance (p = 0.0005). At least 98.12% were rated as “good” and “very good” in both treatment groups for the additional endpoints. Pro-ophta^® Ocular Stick was rated better for almost all the additional endpoints and within the surgery subgroups. The mean number of sticks and surgery duration were 3.5 ± 2.74 and 11.5 (± 8.88) min, respectively, with a positive correlation (r = 0.580) for the Pro-ophta^® Ocular Stick and 3.9 ± 2.45 and 9.5 (± 5.90) min, respectively, with a positive correlation (r = 0.025) for the alternative device. No device-related adverse events occurred. Conclusions Effective ocular sticks play an instrumental role in the outcome of ophthalmic surgeries. The investigational device demonstrated efficiency, yielding good surgical results, usability, and an exceptionally good safety profile.

Purpose: To determine (1) if measurements of surgically induced astigmatism (SIA) as measured by keratometry (K) and total keratometry (TK) differ (2) if SIA affects the magnitude and/or meridian of keratometric astigmatism (3) if SIA evolves over time. Setting: Tertiary care center. Design: Retrospective data analysis. Methods: A swept-source optical coherence tomography biometry dataset (IOLMaster700) consisting of 498 eyes (327 patients) from a tertiary care center was analyzed. For all eyes preoperative and postoperative biometric measurements at 1-month, 3-month, and 6-months postoperative visits were considered for vector analysis of SIA_K and SIA_TK. Results: Centroids in right and left eyes were 0.26 diopters (D) @5 degrees/0.31 D @1 degree for SIA_K and 0.27 D @4 degrees/0.34 D @1 degree for SIA_TK. Centroids for difference vectors K-TK in right and left eyes were 0.02 D @ 176 degrees/0.03 D @6 degrees. The mean SIA magnitudes in right and left eyes were 0.48 ± 0.41 D and 0.50 ± 0.37 D for SIA_K and 0.53 ± 0.42 D and 0.54 ± 0.40 D for SIA_TK. In eyes with ATR astigmatism, an increase in postoperative astigmatism magnitude was more common than a decrease. More than 30% of eyes showed changes in the meridian of more than 15 degrees. Conclusions: Overall, we observed differences in K- and TK-derived SIA, and changes in SIA magnitude over time. For postsurgical interventions, postoperative astigmatism meridian values should be measured to base treatments. Astigmatism magnitude showed a tendency to decrease for steep-meridian incisions and to increase in flat-meridian incisions.

To evaluate corneal stiffening of porcine corneas induced by corneal crosslinking (CXL) with constant irradiance as a function of total fluence.Ninety corneas from freshly enucleated porcine eyes w...

Corneal Crosslinking (CXL) strengthens the keratoconus cornea and prevents further disease progression. Modified crosslinking protocols and different riboflavin solutions have been proposed to opti...

Purpose: The purpose of the study was to evaluate the potential accuracy of different second eye refinement methods in a patient cohort with short axial eye length to assess the performance of intraocular lens (IOL) power calculation schemes in high hyperopes. Methodology: The study design was a single-center, single-surgeon retrospective consecutive case series. The setting of the study was in Augen- und Laserklinik, Castrop-Rauxel, Germany. Patients were assessed after uneventful bilateral cataract surgery implanting either spherical (SA60AT) or aspheric (ZCB00) IOLs. Inclusion criteria were an axial eye length of ≤21.5 mm and/or emmetropizing IOL power of >28.5 dpt. Outcome measures were the mean absolute prediction error (MAE), median absolute prediction error, mean prediction error with standard deviation, median prediction error, and the percentage of eyes with a MAE within 0.25 dpt, 0.5 dpt, 0.75 dpt, or 1.0 dpt. Second eye refinement was performed using the first eye prediction error, either with a correction coefficient of 0.50 (SER1), or an individual coefficient optimized for MAE. Results: A total of 55 patients were assessed. A statistically significant reduction in the absPE after the application of SER1 was observed in 9 of 13 formulae. The SER1 refined Hoffer Q, refined Holladay I, refined Holladay II, refined Kane, refined Okulix, and refined PEARL-DGS provided a smaller absolute prediction error (absPE) than other methods. Conclusion: In this patient cohort with a short axial eye length, the second eye refinement led to a lower MAE in almost all formulae. The use of refinement in Kane, Okulix, PEARL-DGS, and Castrop formulae exhibited the lowest MAE.

Purpose To evaluate the accuracy of intraocular lens (IOL) power calculation in a patient cohort with short axial eye length to assess the performance of IOL power calculation schemes in strong hyperopes. Methodology The study was a single centre, single surgeon retrospective consecutive case series at the Augen- und Laserklinik, Castrop-Rauxel, Germany. Inclusion of patients after uneventful cataract surgery implanting either spherical (SA60AT) or aspheric (ZCB00) IOLs. Inclusion criteria were axial eye length 28.5 D. Lens constants were optimised on a separate patient cohort considering the full bandwidth of axial eye length. Data of one single eye per patient were randomly included. The outcome measures were: mean absolute prediction error (MAE), median absolute prediction error, mean prediction error with SD and median prediction error and the percentage of eyes with an MAE within 0.25 D, 0.5 D, 0.75 D and 1.0 D. Results A total of 150 eyes from 150 patients were assessed. Okulix, PEARL-DGS, Kane and Castrop provided a statistically significantly smaller MAE compared with the Hoffer Q and SRK/T formulae. Conclusion In our patient cohort with short axial eye length, the use of PEARL-DGS, Okulix, Kane or Castrop formulae showed the lowest MAE. The Castrop formula has not been published before, but will be disclosed with a ready-to-use Excel sheet as an addendum to this paper.

Purpose: To evaluate the influence of the type of the keratectasia and preoperative keratometry readings on the efficacy of implantation of iris-fixated phakic anterior chamber intraocular lenses (pIOL) in patients with keratoconus. Methods: In this retrospective study, iris-fixated pIOLs (Artisan/Artiflex (Ophtec®), Verisyse/Veriflex (AMO®)) were implanted in 38 eyes of 22 patients with stable keratoconus. Thirty-six eyes underwent corneal crosslinking (CXL) prior to the lens implantation. The refractive outcome was evaluated 6 weeks postoperatively and the influence of preoperative refraction and topo- and tomographical factors were analyzed. Results: The mean postoperative uncorrected distance visual acuity (UDVA_post) was 0.25 ± 0.15 logMAR and was not statistically different from the mean preoperative corrected distance visual acuity (CDVA_pre), which was 0.24 ± 0.13 logMAR. Twenty-seven eyes (71%) reached UDVA_post/CDVA_pre ≥ 1 (efficacy index), whereas patients with PMD-like ectasia (n = 14) showed significantly (p = 0.003) higher efficacy index (100%) than patients diagnosed with keratoconus (n = 24) (54%). Higher eccentricity of the maximum posterior elevation showed a significant beneficial influence on the efficacy index (p = 0.021). Furthermore, a higher Amsler-Krumeich stage and preoperative MAE were correlated with a worse UDVA_post. The mean absolute spherical equivalent was significantly decreased from 5.71 ± 4.96 D to 1.25 ± 1.20 D (p < 0.001). No significant difference was found in endothelial cell count. Conclusion: The results indicate that the implantation of phakic iris-fixated anterior chamber IOLs is a reasonable refractive option for patients with keratoconus. Keratoconus patients with a pellucidal marginal degeneration (PMD)-like appearance ectasia seem to benefit most from such procedures.

A 46-year-old patient presented with a flip-folded partially dislocated flap after trauma caused by a sheet of paper, four years after a reportedly uneventful laser in situ keratomileusis procedure using microkeratome. Flap re-lift, mechanical debridement, and flap stretching were performed in a first interventional approach. Due to epithelial ingrowth two month after the first intervention, a flap re-lift and mechanical removal of epithelial cells from the stroma bed and flap were performed. In addition, triamcinolone was applied subconjunctivally. Thereafter, best corrected visual acuity of 20/20 was regained and no more epithelial ingrowth was observed. Only few cases of flap dislocation with epithelial ingrowth have been described in the literature following trauma, though none of a permanently inward folded flap. The use of subconjunctival triamcinolone is a new approach to prevent recurrent epithelial ingrowth.