Biomechanical changes following corneal crosslinking in keratoconus patients.

PURPOSE: To evaluate the biomechanical and tomographic outcomes of keratoconus patients up to four years after corneal crosslinking (CXL). METHODS: In this longitudinal retrospective-prospective single-center case series, the preoperative tomographic and biomechanical results from 200 keratoconus eyes of 161 patients undergoing CXL were compared to follow-up examinations at three-months, six-months, one-year, two-years, three-years, and four-years after CXL. Primary outcomes included the Corvis Biomechanical Factor (CBiF) and five biomechanical response parameters obtained from the Corvis ST. Tomographically, the Belin-Ambrósio deviation index (BAD-D) and the maximal keratometry (Kmax) measured by the Pentacam were analyzed. Additionally, Corvis E-staging, the thinnest corneal thickness (TCT), and the best-corrected visual acuity (BCVA) were obtained. Primary outcomes were compared using a paired t-test. RESULTS: The CBiF decreased significantly at the six-month (p < 0.001) and one-year (p < 0.001) follow-ups when compared to preoperative values. E-staging behaved accordingly to the CBiF. Within the two- to four-year follow-ups, the biomechanical outcomes showed no significant differences when compared to preoperative. Tomographically, the BAD-D increased significantly during the first year after CXL with a maximum at six-months (p < 0.001), while Kmax decreased significantly (p < 0.001) and continuously up to four years after CXL. The TCT was lower at all postoperative follow-up visits compared to preoperative, and the BCVA improved. CONCLUSION: In the first year after CXL, there was a temporary progression in both the biomechanical CBiF and E-staging, as well as in the tomographic analysis. CXL contributes to the stabilization of both the tomographic and biomechanical properties of the cornea up to four years postoperatively.

Endothelial Cell Loss in Patients with Phakic Intraocular Lenses. / Endothelzellverlust bei phaken Intraokularlinsen.

Although the safety of phakic intraocular lenses (pIOLs) has been continuously improved over 70-years of development, high endothelial cell losses can occur even with current pIOL models. Numerous studies have demonstrated that the distance of a pIOL to the corneal endothelium plays a crucial role in the extent of endothelial cell loss. For this reason alone, higher endothelial cell loss tends to be observed with anterior chamber lenses than with posterior chamber lenses. Adequate preoperative anterior chamber depth is essential, at least for iris-fixed pIOLs, in order to ensure a safe distance from the endothelium. However, the anterior chamber becomes shallower with age and therefore it may be useful to consider patient age in the safety criteria. Although endothelial cell loss is generally low with current pIOL models, regular monitoring of the endothelial cell density remains essential due to large interindividual differences in patients with pIOLs. If the endothelial cell loss is greater than expected and the follow-up visits confirm the trend, the pIOL should be explanted without delay. The endothelial reserve should be considered on an individual basis by taking into account patient age, physiological endothelial cell loss, and loss due to further surgery. With careful indication and long-term patient care, pIOLs remain a safe treatment option.

Cataract Classification Systems: A Review.

Cataract is among the leading causes of visual impairment worldwide. Innovations in treatment have drastically improved patient outcomes, but to be properly implemented, it is necessary to have the right diagnostic tools. This review explores the cataract grading systems developed by researchers in recent decades and provides insight into both merits and limitations. To this day, the gold standard for cataract classification is the Lens Opacity Classification System III. Different cataract features are graded according to standard photographs during slit lamp examination. Although widely used in research, its clinical application is rare, and it is limited by its subjective nature. Meanwhile, recent advancements in imaging technology, notably Scheimpflug imaging and optical coherence tomography, have opened the possibility of objective assessment of lens structure. With the use of automatic lens anatomy detection software, researchers demonstrated a good correlation to functional and surgical metrics such as visual acuity, phacoemulsification energy, and surgical time. The development of deep learning networks has further increased the capability of these grading systems by improving interpretability and increasing robustness when applied to norm-deviating cases. These classification systems, which can be used for both screening and preoperative diagnostics, are of value for targeted prospective studies, but still require implementation and validation in everyday clinical practice.

Refractive outcomes of small lenticule extraction (SMILE) Pro® with a 2 MHz femtosecond laser.

PURPOSE: To evaluate the initial visual outcomes of Small Incision Lenticule Extraction (SMILE) Pro® using a 2 MHz femtosecond laser (VisuMax 800, Carl Zeiss Meditec) and to assess the efficacy, safety, predictability, accuracy, and complication rate. METHODS: This retrospective analysis included eyes which underwent the SMILE Pro® procedure using VisuMax 800 femtosecond laser to correct myopia. All surgeries were performed by one surgeon (DB). Follow-up was conducted 3 months postoperatively to evaluate visual outcomes after neuroadaptation, corrected visual acuity (CDVA) and intra- and postoperative complications. RESULTS: One hundred and fifty-two eyes of 82 patients (mean age 31 ± 6 years) results at 3 months are presented. The mean spherical equivalent (SE) was - 4.44 ± 1.86 D preoperatively while -0.24 ± 0.32 D postoperatively. 99% of eyes achieved SE within ± 1.0 D of attempted correction and 91% were within ± 0.5 D. Efficacy index was 0.93 while the safety index was 1. No complications occurred intra- or postoperatively. No eyes lost more than 1 line of their preoperative CDVA. All highly myopic eyes (- 6.25 to - 10.00 D; n = 18) achieved 20/20 at 3 months postoperatively and were within 0.5 D from the attempted SE and no eyes lost more than 1 line of CDVA. CONCLUSION: The SMILE Pro® is a safe, efficient, and predictable procedure for the treatment of myopia and myopic astigmatism, with comparable results of conventional SMILE surgery. High myopic eyes achieve better results than low and moderate myopia. No complications were recorded in our patients.

Capsule Dynamics, Implantation, and Explantation of the Smaller Incision, New-Generation Implantable Miniature Telescope: a Miyake-Apple Study.

PURPOSE: The smaller incision, new-generation implantable miniature telescope is a novel implant to optimize vision in retinal patients with central vision loss. Using Miyake-Apple techniques we visualized the device implantation, repositioning, and explantation, while noting capsular bag dynamics. METHODS: Using the Miyake-Apple technique, we assessed capsular bag deformation after successful implantation of the device in human autopsy eyes. We assessed rescue strategies for converting a sulcus implantation to a capsular implantation and explantation strategies. We noted the occurrence of posterior capsule striae, zonular stress, and the haptics' arc of contact with the capsular bag after implantation. RESULTS: Acceptable zonular stress was observed during the successful implantation of the SING IMT. When it was implanted in the sulcus, one could reposition the haptics into the bag with two spatulas using counter-pressure in an effective strategy despite inducing tolerable, medium zonular stress. A similar technique, in reverse, allows safe explantation without damaging the rhexis or the bag, while inducing similar medium, tolerable zonular stress. In all eyes we examined, the implant considerably stretches the bag, inducing a capsular bag deformation and posterior capsule striae. CONCLUSION: The SING IMT can be safely implanted without significant zonular stress. In sulcus implantation and explantation, repositioning of the haptic is achievable without perturbing zonular stress using the presented approaches. It stretches average-sized capsular bags to support its weight. This is achieved by an increased arc of contact of the haptics with the capsular equator.

Nozzle tip damage in three generations of intraocular lens injector models: an experimental laboratory study.

PURPOSE: To assess the nozzle tip damage of IOL injectors in three generations from the same manufacturer using the self-developed system-the Heidelberg Score for IOL Injector Damage. SETTING: David J Apple Center for Vision Research, Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany DESIGN: Experimental laboratory study METHODS: The nozzle tip damage of three injector models (Emerald, iTec, and Simplicity) was determined using the Heidelberg score for IOL injector damage. Damage to the nozzle tip was examined under a microscope and graded as follows: no damage (score 0), slight scratches (1), deep scratches (2), extensions (3), cracks (4) and bursts (5). The total scores for each injector system were the sum of scores for all injectors in this model. Total scores of the three injector systems were evaluated and compared. The nozzle tip parameters (diameters, tip angles) were also measured in each group. RESULTS: The Emerald system achieved the highest total scores, while the other two systems achieved similar total scores. There was no statistically significant difference in the total scores between the study groups (P > 0.05). The outer cross-sectional diameters were 2.10 and 2.10 mm for Emerald, 1.80 and 1.78 mm for iTec, and 1.78 and 1.80 mm for Simplicity. The thickness of the nozzle tips was 0.13 mm (Emerald), 0.17 mm (iTec) and 0.17 mm (Simplicity). The tip angle for three injector models was 35° (Emerald), 45° (iTec), and 45° (Simplicity). CONCLUSIONS: Although different injector models exhibited varying degrees of damage to the nozzle tip, all injector models generally showed relatively good results. Newer generations of IOL injector models tend to perform better in terms of nozzle tip damage after IOL implantation.

Video analysis of optic-haptic-interaction during hydrophobic acrylic intraocular lens implantation using preloaded injectors.

OBJECTIVE: To compare the optic-haptic interaction of different hydrophobic acrylic IOLs after using six preloaded injectors. METHODS: We reviewed the video-recordings of procedures on a total of 388 eyes that underwent phacoemulsification and intraocular lens (IOL) implantation. For six preloaded injectors: multiSert (Hoya Surgical Optics) [System 1], TECNIS Simplicity (Johnson & Johnson Vision) [System 2], TECNIS iTec (Johnson & Johnson Vision) [System 3], AutonoMe (Alcon, Laboratories) [System 4], Bluesert (Carl Zeiss Meditec) [System 5], and Prosert (OphthalmoPro GmbH) [System 6], we noted in each case the time of IOL delivery and made a descriptive observation of IOL insertion and optic-haptic-interaction. RESULTS: We defined standard haptic behavior where the haptics emerged "folded" from the injector and quickly recovered their pre-implantation appearance. The incidence where the leading haptic emerged in a deformed way for System 1 was 20%, System 2: 19%, System 3: 14%, System 4: 56%, System 5: 24% and System 6: 5%. For trailing haptic deformed behavior, the incidence was 36%, 6%, 4%, 8%, 18% and 2%, respectively for Systems 1 to 6. Optic-haptic adhesion occurred in 2% of cases for System 1, 44% for System 2, 52% for System 3, 48% for System 4, and 11% for System 6 (P < 0.05). Adhesion was not found with System 5. CONCLUSIONS: We observed different deformed behavior for leading and trailing haptics in the six preloaded systems, some systems had as much as 52% optic-haptic adhesion.

Clinical outcomes of bilateral implantation of new generation monofocal IOL enhanced for intermediate distance and conventional monofocal IOL in a Korean population.

BACKGROUND: To compare the clinical outcomes of bilateral implantation of enhanced intermediate function intraocular lenses (IOLs) and standard monofocal IOLs. METHODS: In this prospective, randomized, comparative controlled study, we compared the visual outcomes of patients who underwent bilateral cataract surgery at the Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, with either enhanced monofocal IOLs (Tecnis Eyhance, ICB00, Johnson and Johnson Vision Care, Inc) (Group 1) or standard monofocal IOLs (Tecnis, ZCB00, Johnson and Johnson Vision Care, Inc) (Group 2). The assessment included monocular and binocular uncorrected distance visual acuity (UDVA), uncorrected intermediate (UIVA at 60 cm) and near (UNVA at 40 cm) visual acuity, uncorrected defocus curves, contrast sensitivity testing (CST), and reading speed test using Quality of vision was evaluated using the Visual Function Questionnaire (VFQ-25). RESULTS: At 3-months postoperatively, monocular and binocular outcomes of UIVA and UNVA were statistically significantly better in Group 1 (P < 0.05). The binocular uncorrected defocus curve of Group 1 showed statistically significantly better outcomes at vergence ranges of -1.5 to -4.0 D (P < 0.05). Significantly higher reading speed test was also observed in Group 1 in all ranges tested (1.0 to 0.1 LogMAR) (P < 0.05). There were no statistically significant differences in CST between groups. CONCLUSIONS: Bilateral implantation of enhanced monofocal IOLs provided better vision at intermediate and near distances compared to standard monofocal IOLs, while maintaining good distance vision and contrast sensitivity.

Evaluation of Nozzle Tip Damage in Intraocular Lens Injectors with V-Shaped Notch.

INTRODUCTION: Damage to the nozzle tips of intraocular lens (IOL) injectors has been associated with various adverse events and even IOL surface abnormalities after IOL implantation. In this study, nozzle tip damage of three different injector models with v-notched nozzle tips was systematically evaluated using our self-developed system - the Heidelberg Score for IOL injector damage. METHODS: Nozzle tip damage was categorized into 6 grades: no damage (grade 0), slight scratches (1), deep scratches (2), extensions (3), cracks (4), and bursts (5). Each grade was assigned to a score of 0-5. In each IOL injector group, all IOLs were divided into 2 subgroups based on IOL power: +15 to +21D group and +21 to +26D group. The total scores for each group were the sum of scores for all injectors in this group. Further analysis was performed on the nozzle tip configuration and parameters in each injector model. RESULTS: The median (Q1-Q3) for each injector group in group +15 to +21D was 1.5 (1-2) for Avansee, 4 (3-4) for iSert, and 4 (3-4) for multiSert. A statistically significant difference was found between Avansee and iSert (p < 0.001) as well as between Avansee and multiSert (p < 0.01) in terms of median scores. The median (Q1-Q3) for each injector group in group +21 to +26D was 1.5 (1-2) for Avansee, 4 (4-4) for iSert, and 3 (3-3.75) for multiSert. A statistically significant difference was found between Avansee and iSert in terms of median scores (p < 0.001). The outer cross-sectional diameters were 1.80 and 1.78 mm for Avansee, 1.70 and 1.69 mm for iSert, and 1.69 and 1.68 mm for multiSert. The radii of each notch-based circle were 0.21 mm (Avansee), 0.09 (iSert), and 0.06 (multiSert), respectively. The tip angles for three injector models were 48° (Avansee), 46° (iSert), and 37° (multiSert). CONCLUSIONS: Avansee showed the least nozzle tip damage of all three groups. Compared with our earlier study using preloaded injectors with intact endpieces, all the injector groups with v-notched nozzle tips had more damage to the nozzle tip. It was found that the closer the notch of the nozzle tip was to the letter "V," the more damaged the nozzle tip was after IOL implantation.

Aetiology and Management of IOL Dislocations. / Ursachen und Management von IOL-Dislokationen.

Early (< 3 months) intraocular lens (IOL) dislocation occurs due to insufficient fixation in the capsular bag, while late dislocation (≥ 3 months) is due to increasing insufficiency of the zonular apparatus. Iris-fixated IOL (IFIOL) and suture- or sutureless-fixated scleral IOL (SFIOL) are currently the most commonly used methods when IOL exchange is indicated. Different methods of scleral fixation with or without sutures have been described. The most important techniques are summarised in this paper. IFIOL and SFIOL allow comparable visual outcomes but differ in their risk profile. The decision of which method to use should be made case by case and in accordance with the surgeon's preference.

Fusarium Keratitis on the Rise - a Clinical Review. / Die Fusarien-Keratitis auf dem Vormarsch ­ eine aktuelle klinische Übersicht.

Fungal keratitis due to Fusarium species is a rare but serious ocular disease. Due to its rapid progression, often late diagnostic confirmation as well as limited topical treatment options, this is potentially sight threatening. Increasing contact lens use and global climate change have been suggested to be factors leading to an increase in cases of fusarium keratitis, even in regions with moderate climate. Early recognition and initiation of antimycotic treatment, as well as early surgical treatment by penetrating keratoplasty are decisive for the outcome.

Evaluating the Predictability of Postoperative Target Refraction Using the Prototype of a New Intraoperative Aberrometer. / Evaluation des Prototyps eines neuen intraoperativen Aberrometers für die Vorhersage der postoperativen Zielrefraktion.

Despite all the progress in cataract and refractive lens surgery, refractive surprise is common in clinical practice. A significant postoperative refractive error is particularly annoying - and contributes to the patient's dissatisfaction with the procedure and the surgeon - when a multifocal IOL, an EDOF-IOL or a toric IOL has been implanted. The relatively new technology of intraoperative aberrometry offers the surgeon the option to intraoperatively measure the eye and its refraction, either directly after lens extraction and/or following IOL implantation. Currently, three different systems are available. In a number of studies, the technology has shown a better refractive predictability than preoperative biometry. Besides giving an evaluation of the prototype of a new intraoperative aberrometer, the I-O-W-A system, we also present our results on the influence of the kind of anaesthesia chosen and of two different IOL designs on the predictability of intraoperative aberrometry.

Reversible Multifocality Achieved Through Polypseudophakia. / Reversible Multifokalität durch Polypseudophakie.

Simultaneous implantation of a monofocal or monofocal toric intraocular lens (IOL) into the capsular bag and a multifocal IOL into the ciliary sulcus, referred to as duet procedure, allows us to create multifocality that is more easily reversible than the implantation of a capsular bag-fixated multifocal IOL. The optical quality and results after the duet procedure are equivalent to those of a capsular bag-fixated multifocal IOL. Patients who cannot tolerate the side effects of multifocal optics or who develop an ocular condition leading to loss of function such as age-related macular degeneration (AMD) or glaucoma in the course of their lives may benefit from the reversibility of the procedure.

Opacification of Hydrophilic Acrylic Intraocular Lenses: Overview of Laboratory Methods for Histological Analysis and Replication of IOL Calcification. / Eintrübung hydrophiler Acrylintraokularlinsen: Überblick zu Labormethoden der histologischen Analyse und Replikation der Kalzifikation.

Opacification of intraocular lenses (IOLs) due to material changes is a serious complication that can compromise the good visual outcomes of uncomplicated cataract surgery. In hydrophobic acrylic IOLs, opacification can result from glistening formation, while in hydrophilic acrylic IOLs, there is a risk of calcification due to the formation of calcium phosphates within the polymer. Over time, various methods have been developed to investigate calcification in hydrophilic acrylic IOLs. The aim of this article is to provide an overview of standard histological staining and models used to simulate IOL calcification. Histological staining can be used to detect calcification and assess the extent of crystal formation. The development of in vivo and in vitro replication models has helped to identify the underlying pathomechanisms of calcification. In vivo models are suitable for assessing the biocompatibility of IOL materials. Bioreactors as an in vitro model can be used to investigate the kinetics of crystal formation within the polymer. The replication of IOL calcification under standardized conditions using electrophoresis allows for the comparison of different lens materials with respect to the risk of calcification. The combination of different analytical and replication methods can be used in the future to further investigate the pathomechanisms of calcium phosphate crystal formation and the influence of risk factors. This may help to prevent calcification of hydrophilic acrylic IOLs and associated explantation and complications.

Change in Subfoveal Choroidal Thickness following Cataract Surgery Imaged with Enhanced Depth Imaging Optical Coherence Tomography.

BACKGROUND: Due to its invasive nature, cataract surgery can lead to inflammatory processes in the posterior segment, which can result in prolonged recovery times, reduced functional outcomes, and late-onset complications. The aim of the current study was to identify wherever phacoemulsification parameters play a role in choroidal thickness change following cataract surgery. METHODS: This prospective single-center study enrolled 31 patients (31 eyes) scheduled to undergo routine cataract surgery. Patients with previous ocular surgeries, pathologies or general disorders affecting vision were excluded. Patients were examined preoperatively, as well as 1, 4, and 12 weeks after surgery. Corrected distance visual acuity (CDVA), intraocular pressure (IOP) as well as cumulative dissipated energy (CDE), ultrasound time (UT), and fluids used during surgery were recorded. Subfoveal choroidal thickness was measured manually by two masked independent experts using enhanced depth imaging (EDI) optical coherence tomography (OCT). Furthermore, cataract density was automatically calculated using a custom MATLAB script and an anterior segment OCT. RESULTS: Subfoveal choroidal thickness increased significantly (p < 0.001, Student's paired sample t-test) and continuously during the 12-week-long follow-up period. Both the nuclear lens density and the improvement in CDVA correlated significantly with this increase (r = 0.413, p = 0.021 and r = 0.421, p = 0.018, respectively). Neither the CDE (r = 0.334, p = 0.071), the UT (r = 0.102, p = 0.629), the amount of fluid used (r = 0.237, p = 0.27) nor the decrease in IOP (r = - 0.197, p = 0.288) showed any significant correlation with the choroidal swelling. CONCLUSION: Cataract surgery leads to an increase in subfoveal choroidal thickness. While no statistically significant correlation to the phacoemulsification parameters could be established, this might be because of a selection bias due to the technological constraints of the OCT. Nevertheless, the choroid might play a central role in early- and late-onset complications.

Biomechanical Analysis of Tomographically Regular Keratoconus Fellow Eyes Using Corvis ST. / Biomechanische Analyse von tomografisch unauffälligen Keratokonus-Partneraugen mit dem Corvis ST.

BACKGROUND: Keratoconus is a bilateral, yet asymmetric disease. In rare cases, the second eye may show no signs of tomographic changes. The purpose of this study was to analyze the biomechanical characteristics in tomographically regular keratoconus fellow eyes. MATERIALS AND METHODS: This retrospective, consecutive case series analyzed 916 eyes of 458 patients who presented to our keratoconus clinic between November 2020 and October 2022. Primary outcome measures included best-corrected visual acuity (BCVA), tomographic Scheimpflug analysis using Pentacam AXL (Oculus, Wetzlar, Germany), and biomechanical assessment using Corvis ST (Oculus, Wetzlar, Germany). Tomographic changes were assessed via analysis of the anterior and posterior curvature, K-max, thinnest corneal thickness (TCT), the Belin/Ambrosio Deviation Display (BAD-D), and the ABCD-Grading. Biomechanical changes were analyzed using Corvis Biomechanical Index (CBI) and Tomographic Biomechanical Index (TBI). RESULTS: Of 916 eyes, 34 tomographically regular fellow eyes (7.4%) were identified and included in the analysis. Overall, the mean BCVA was - 0.02 ± 0.13 logMAR. Tomographic analysis showed mean K-max of 43.87 ± 1.21 D, mean TCT of 532 ± 23 µm, and mean BAD-D of 1.02 ± 0.43. Biomechanical analysis demonstrated mean CBI of 0.28 ± 0.26 and mean TBI of 0.34 ± 0.30. While normal CBI-values were observed in 16 (47%) of 34 eyes, only 13 eyes (38%) showed a regular TBI and only 7 eyes (21%) showed regular TBI and CBI. The sensitivity of CBI and TBI to detect a tomographically normal keratoconus fellow eye was 53% and 62%, respectively. CONCLUSION: A highly asymmetric corneal ectasia with regular tomographic finding in a fellow eye is rare among keratoconus patients. In such cases, a biomechanical analysis may be useful in detecting early signs of corneal ectasia. In our analysis, the TBI showed high sensitivity for detecting a biomechanical abnormality in tomographically regular fellow eyes.

Differential Diagnosis of Changes in Intraocular Lenses. / Differenzialdiagnostik von Veränderungen in Intraokularlinsen.

Differentiating between various intraocular lens (IOL) changes can be a challenge. In particular, certain IOL models carry the risk of late postoperative calcification. A major cause of IOL exchange surgery could be avoided if appropriate modifications were made during the IOL manufacturing process. The use of a hydrophilic acrylate carries the risk of IOL calcification, especially when a secondary procedure, such as a pars plana vitrectomy or other procedures using gas or air, is performed. In secondary IOL calcification, there is a wide range of opacification patterns, which are usually located in the centre on the anterior surface of the IOL or sometimes elsewhere. Often, granular deposits accumulate just below or on the surface of the IOL, leading to significant deterioration in visual quality and eventually requiring IOL exchange surgery. Therefore, in the case of eyes requiring secondary surgical intraocular intervention in the future, the use of hydrophilic IOLs should be critically evaluated. With regard to hydrophobic IOL materials, there are clear differences in the susceptibility to the formation of glistenings. Over time, there has been a significant decrease in glistening formation over the past 30 years due to optimisation of the material. With hydrophobic IOLs, special care should also be taken to avoid mechanical damage. In general, the only treatment option for functionally-impairing IOL opacification is surgical lens exchange, which carries potential risks of complications. In cases with a low degree of functional impairment, and especially in eyes with additional ocular diseases, it may be difficult to weigh the risk of additional surgery against the potential benefit. In some cases, it may be more appropriate not to perform an IOL exchange despite the IOL opacification. Recent visualisation methods that allow high-resolution analysis of the opacities in vivo and in vitro may be used in the future to estimate the functional effects of various IOL material changes on the optical quality.

THE NOVEL USE OF HIGH-FLOW POLYIMIDE CANNULAS TO IMPROVE SILICONE OIL INJECTABILITY IN VITREORETINAL SURGERY.

PURPOSE: The injection of high-viscosity silicone oil lengthens injection time. New polyimide cannulas offer a greater inner diameter than conventional metal cannulas at the same gauge. We compared the injection time for polyimide and metal cannulas at 23 G for a variety of silicone oils including a 12,500-mPas prototype oil. METHODS: In this laboratory study, injection time was measured three times per cannula and per oil. Warming the oil before injection to up to 42°C was also evaluated. Finally, the feasibility of polyimide cannulas was tested in vitrectomized porcine eyes. RESULTS: The 23-G polyimide cannula mostly decreased injection times. The time to inject 5 mL of Siluron Xtra and Siluron 5000 decreased by 6:02 (76.9%) minutes (483 vs. 121 seconds) and 12:01 (74.7%) minutes (973 vs. 252 seconds), respectively. Although the 23-G metal cannula failed to inject 12,500 mPas oil, 5 mL was injected in 10:21 minutes using the polyimide cannula. Prewarming Siluron 5000 to 42°C lowered the injection time by 9.0% and by 12.1% when using the metal or polyimide cannula, respectively. CONCLUSION: Polyimide cannulas allow a clinically relevant decrease in injection time. They may not only shorten surgery time but could also ease the use of next-generation ultra-high-viscosity silicone oils. Prewarming silicone oil leads to decreased injection times.

THE LOSS OF INFRARED LIGHT SENSITIVITY OF PHOTORECEPTOR CELLS MEASURED WITH TWO-PHOTON EXCITATION AS AN INDICATOR OF DIABETIC RETINOPATHY: A Pilot Study.

PURPOSE: Human photoreceptors are sensitive to infrared light (IR). This sensitivity can be used as a novel indicator of retinal function. Diabetic retinopathy patients were assessed using in vivo two-photon excitation and compared their scotopic IR threshold with that of healthy patients. METHODS: Sixty-two participants, 28 healthy and 34 with diabetic retinopathy, underwent a comprehensive eye examination, where visual acuity and contrast sensitivity were assessed. Infrared thresholds were measured in the fovea and parafovea following 30-minute dark adaptation. A two-photon excitation device was used with integrated pulsed laser light (1,045 nm) for sensitivity testing and scanning laser ophthalmoscopy for fundus imaging. RESULTS: The mean Snellen visual acuity of diabetic patients (6/7.7) was worse than that of the healthy patients (6/5.5), which was significantly different (P < 0.001). Disease patients had decreased contrast sensitivity, especially at 6 and 18 cycles/degree. The mean retinal sensitivity to IR light in eyes with diabetic retinopathy (11.6 ± 2.0 dB) was significantly (P < 0.001) lower than that in normal eyes (15.5 ± 1.3 dB). CONCLUSION: Compared with healthy control subjects, the IR light sensitivity of diabetic patients was significantly impaired. Two-photon measurements can be used in the assessment of retinal disease, but further studies are needed to validate IR light stimulation in various stages of diabetic retinopathy.

Laboratory analysis and ray visualization of diffractive optics with enhanced intermediate vision.

BACKGROUND: To assess the optical behavior of a new diffractive intraocular lens (IOL) and compare its performance to that of an established extended-depth-of-focus (EDOF) IOL. METHODS: This study assessed the Proming EDOF Multifocal AM2UX [Eyebright Medical Technology (Beijing) Co., Ltd., China] and the AT LARA 829MP [Carl Zeiss Meditec, Germany]. An experimental set-up with 0.01% fluorescein solution and monochromatic light (532 nm) was used to visualize the IOLs' ray propagation. In addition, the optical quality of the IOLs was assessed by measuring the modulation transfer function (MTF) values at 50lp/mm and 3.0 and 4.5 mm apertures on the optical bench OptiSpheric® IOL PRO II [Trioptics GmbH, Germany]. RESULTS: The ray propagation of the two IOLs showed two distinct foci. Light intensity assessment revealed that both IOLs allocate more energy to primary than secondary focus. At 3.0 mm pupil, the MTF values at 50lp/mm for the primary focus were 0.39 and 0.37, and for the secondary focus, 0.29 and 0.26 for the AT LARA and Proming IOLs, respectively. At 4.5 mm pupil, the single-frequency MTF for the primary focus was 0.51 and 0.24 and for the secondary focus 0.21 and 0.15 for the AT LARA and Proming IOLs, respectively. CONCLUSIONS: When tested with an aberration-free model cornea under monochromatic conditions, the Proming behaved as a low-add bifocal lens; however, its properties did not differ much from the well-established AT LARA EDOF IOL. The AT LARA outperformed the Proming at low defocus (up to 2D), while the latter demonstrated better image quality in the 2-3D range.