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PURPOSE To evaluate the influence of anterior capsule rhexis shape, dimension and eccentricity on IntraOcular Lens (IOL) position. SETTING laboratory investigation. DESIGN Computational modelMethods: a finite element model of the human crystalline lens capsule and zonule was created and the anterior capsule opened to simulate centred and decentred circular and elliptic rhexis. The model calculated capsular bag stress, IOL rotation, tilt, decentration and vaulting, related to both capsular landmarks (absolute) and to a reference IOL position defined as that obtained with a 5 mm circular and centred rhexis. RESULTS Average Von Mises stress along IOL major axis Z was significantly higher than along the perpendicular X-axis in all cases (p

Purpose: To evaluate the accuracy and the inter and intra-observer reliability of the centration assessment of extended depth of focus (EDOF) contact lenses (CL) using corneal topography. Method: EDOF soft CLs (Mylo, Mark'Ennovy) were fitted on thirty-three myopic students (25 females), aged 19–28 years (22.7 ± 2.0 years). For any EDOF CL, a topography over the CL and a slit lamp (SL) digital picture were taken in random order. For the topographic images, the position of the EDOF CL centre, with respect to the pupil centre, was detected by two different practitioners (one newly graduated and one with more than 20 years of clinical experience respectively) and repeated after 15 days. This measurement was compared to the one taken through the SL, considered as the gold standard, and assessed using the instrument software. Results: EDOF CLs resulted decentred inferiorly and temporally ranging, in the case of slit lamp assessment, between −0.27 ± 0.19 and 0.22 ± 0.23 mm horizontally and between −0.12 ± 0.31 and −0.17 ± 0.34 mm vertically, for the right and left eye respectively. The accuracy of the topographic assessment in determining EDOF CL centration was found to be very good compared to the SL assessment. No differences were found for the left eye, whereas in the right eye, a less temporally decentred position of the CL was detected by the topographical method (p < 0.05). However, this difference appeared clinically negligible (0.14 ± 0.22 mm). Inter-observer reliability (the differences between the two practitioners in assessing the EDOF centre) resulted significant only for the vertical coordinates of the centre position (p < 0.05). Concerning intra-observer reliability, better coefficient of precision and reliability between measurements within the same session were achieved by the more experienced practitioner, as well as a better level of the intraclass correlation coefficient in test–retest. Conclusion: The centration of the EDOF CL investigated in this study can be accurately detected by a corneal topography performed over CLs. Inter-observer reliability resulted good whereas the intra-observer reliability resulted partially affected by the level of clinical experience of the practitioner.

Iris defects and distorted pupils are commonly managed with iris suturing techniques that aim to close the defect and/or reform the physiological pupil. The re-creation of an optimally sized and centered pupil is often challenging because of missing iris, asymmetrical iris damage, or variable tension around the pupil. Current options include removing or cutting iris tissue using microscissors or the vitreous cutter, instrument stretching, or postoperative laser photocoagulation. Iris microendodiathermy is a simple technique that is minimally traumatic, titratable, and controlled, avoids excessive tissue manipulation, and is able to create a round cosmetically pleasing pupil. A bipolar endodiathermy cautery is applied to the iris stroma to induce tissue contraction and to gently pull the pupil in the meridian to which probe is applied. Endothermal pupilloplasty (EDP) may be used to recenter or enlarge a small pupil, thereby avoiding additional trauma inflicted by a vitrector or microscissors that physically cuts the iris.

PURPOSE To define and compare the centration of the ablation effect in laser in situ keratomileusis (LASIK) with the corresponding effect in small-incision lenticule extraction (SMILE), in myopic laser vision correction to possibly explain the refractive performance differences noted between the two procedures in a contralateral eye study. SETTING Private ambulatory eye surgery unit. DESIGN Prospective randomized contralateral eye study. METHODS In 22 consecutive patients (44 eyes), 1 eye was prospectively randomized to undergo myopic topography-guided LASIK treatment and the contralateral eye to undergo SMILE; digital image analysis of the achieved centration to the aimed corneal vertex was assessed for both procedures on perioperative Scheimpflug tangential curvature maps, using a proprietary digitized methodology. RESULTS The radial displacement measured in micrometers in the above treated 44 eyes, between the attempted centration point on the corneal vertex vs the center of the measured effective anterior corneal curvature flattening was on average 130 ± 62 mm in the 22 eyes of LASIK group and 313 ± 144 mm in the 22 contralateral eyes of the SMILE group (P < .001). CONCLUSIONS In this contralateral eye study, topography-guided myopic LASIK was found to achieve significantly better effective centration compared with myopic SMILE, in regard to digitally measured decentration of the effective refractive change achieved in the anterior corneal curvature from the corneal vertex. This may explain the previously reported superior visual outcomes in the LASIK group eyes when compared with the contralateral SMILE group eyes.

Subluxation of the crystalline lens in childhood confronts the surgeon with a dilemma: to operate or to wait and see. Surgery is usually not performed when the subluxation is still limited. However, postponing the surgery increases the surgical difficulty as the capsular bag becomes more difficult to use as a means of support for the intraocular lens (IOL). A large number of children already present a pronounced subluxation at first presentation. In this paper, we describe a technique to optimise centration and fixation of the bag-in-the-lens (BIL) IOL in children younger than 7 years of age with congenital ectopia lentis.Between October 2019 and December 2020, we performed lens extraction using a combination of bean-shaped segments to support the BIL IOL and a 6 - 0 polypropylene loop fixated at the sclera, following the Yamane technique, for the purpose of centration. We used this technique for seven eyes of four patients. The patients were between 2 and 6 years old; 3 boys and 1 girl. A definite diagnosis of Marfan syndrome was made for two children; for the other two, there was no proven underlying pathology. The luxation was upwards in all cases. The degree of luxation was severe in all eyes. The preoperative refraction values showed high astigmatism values for all eyes, ranging from 6.5 to 11.25 dioptres. Three out of the four patients were myopic, ranging from - 1.5 to - 9 dioptres.The surgery could be performed without major complications in all eyes. Good centration was obtained, which remained stable in the postoperative period. Refraction improved with greatly diminished degrees of astigmatism (ranging from 0.25 to 3 dioptres) and myopia (spheres ranging from - 2 to + 1.75 dioptres).Our novel technique incorporated the BIL technique with the addition of bean-shaped segments and a polypropylene 6/0 suture fixated at the sclera. In this way, we were able to obtain good centration and stability of the implanted IOL, as well as a good refractive outcome in all cases.Die Subluxation der Augenlinse im Kindesalter stellt den Chirurgen vor ein Dilemma: operieren oder abwarten und sehen. Eine Operation wird normalerweise nicht durchgeführt, wenn die Subluxation noch begrenzt ist. Die Verschiebung der Operation erhöht jedoch die chirurgische Schwierigkeit, da die Verwendung des Kapselsacks als Mittel zur Unterstützung der IOL schwieriger wird. Eine große Anzahl von Kindern zeigt bereits bei ihrem ersten Besuch eine ausgeprägte Subluxation. Wir beschreiben eine Technik zur Optimierung der Zentrierung und Fixierung der Intraokularlinse (IOL) mit Bag in the Lens (BIL) bei Kindern unter 7 Jahren mit angeborener Ectopia lentis.Zwischen Oktober 2019 und Dezember 2020 führten wir eine Linsenextraktion durch, wobei wir eine Kombination aus bohnenförmigen Segmenten zur Unterstützung der BIL-IOL und einer 6 – 0-Polypropylenschlaufe benutzten, die zum Zweck der Zentrierung nach der Yamane-Technik an der Sklera fixiert wurde. Wir verwendeten diese Technik für 7 Augen von 4 Patienten. Die Patienten waren zwischen 2 und 6 Jahre alt; 3 Jungen und 1 Mädchen. Eine eindeutige Diagnose des Marfan-Syndroms wurde für 2 Kinder gestellt, für die anderen 2 gab es keine nachgewiesene zugrunde liegende Pathologie. Die Luxation war in allen Fällen nach oben gerichtet. Der Luxationsgrad war in allen Augen stark ausgeprägt. Die präoperativen Refraktionswerte zeigten für alle Augen hohe Astigmatismuswerte im Bereich von 6,5 bis 11,25 dpt. Drei der 4 Patienten waren kurzsichtig und reichten von − 1,5 bis − 9 dpt.Die Operation konnte in allen Augen ohne größere Komplikationen durchgeführt werden. Es wurde eine gute Zentrierung erreicht, die in der postoperativen Phase stabil blieb. Die Refraktion verbesserte sich mit stark verringertem Astigmatismus (im Bereich von 0,25 bis 3 dpt) und Myopie (Sphären im Bereich von − 2 bis + 1,75 dpt).Diese neuartige Technik unter Verwendung der BIL-Technik mit der Zugabe von bohnenförmigen Segmenten und einer an der Sklera befestigten Polypropylen-6/0-Naht ermöglichte es uns, in allen Fällen eine gute Zentrierung und Stabilität der implantierten IOL sowie eine gute Brechung zu erreichen.

The purpose of this study is to compare pupil versus corneal vertex-centered ablation for myopic laser refractive surgery. This study is a retrospective case series of right eyes of consecutive myopic patients undergoing either photorefractive keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK) with pupil or corneal vertex-centered ablation from January 2018 to April 2018. Overall 258 eyes of 258 patients were included. Of the 104 that underwent LASIK, 52 were treated centered on the corneal vertex (50%), and of the 154 that underwent PRK, 77 were treated centered on the corneal vertex (50%). There were no significant differences in baseline age, gender, spherical equivalence, sphere, cylinder, or angle kappa between both groups in either LASIK or PRK. There were no significant differences between the corneal vertex-centered and pupil-centered groups in terms of efficacy index (LASIK: 1.02 ± 0.14 vs 1.01 ± 0.13, p = 0.86; PRK: 1.00 ± 0.13 vs 0.99 ± 0.15, p = 0.61), safety index (LASIK: 1.02 ± 0.12 vs 1.01 ± 0.13, p = 0.70; PRK:1.02 ± 0.12 vs 1.02 ± 0.09, p = 0.97), and residual astigmatism (LASIK: 0.26 ± 0.25 vs 0.23 ± 0.28, p = 0.65; PRK:0.37 ± 0.41 vs 0.39 ± 0.31, p = 0.78). In mixed effect models, there were no significant differences between the corneal vertex-centered and pupil-centered groups when accounting for angle kappa (p > 0.05). Patients with large angle kappa (> 300 μm) eyes yielded similar results (p > 0.05). For conclusion, in myopic refractive surgery, performing ablation centered on the corneal vertex or on the pupil leads to similar outcomes regardless of the amount of angle kappa.

To evaluate surgical and refractive outcomes of a new sutured scleral fixation technique in the management of subluxated intraocular lenses (IOLs). Nineteen eyes treated with the new scleral fixation technique were included. The mean corrected distance visual acuity (CDVA), postoperative refraction error, mean endothelial cell count (ECC), and complications were recorded. All patients were evaluated immediately postoperatively, at 1 and 7 days, and then at 1, 3, and 6 months. The mean duration of follow-up of the patients was 10 months (range, 6–15 months). The mean CDVA was 0.41 ± 0.1 logMAR (logarithm of minimum angle of resolution) preoperatively and was 0.08 ± 0.07 logMAR postoperatively. The mean astigmatism was − 2.22 ± 1.86 D preoperative and was − 0.86 ± 0.58 D postoperative. The mean preoperative and postoperative ECC was 2455 ± 288 and 2352 ± 288, respectively. One patient (5.26%) experienced vitreous hemorrhage, and two (10.52%) experienced intraocular pressure elevation. IOL tilt and decentralization, conjunctival erosion, and cystoid macular edema were not observed in any eyes during follow-up. This new IOL repositioning technique can be applied in a short surgical time and provides a stable IOL centration on long-term follow-up.

Introduction: Since the introduction, femtosecond laser-assisted cataract surgery (FLACS) was believed to revolutionize cataract surgery. However, the judgment of clinical benefits was found to be far more complex than initially might have been thought. The aim of this review was to analyze the benefits and drawbacks of FLACS compared to traditional phacoemulsification cataract surgery. Results: The benefits of FLACS include lower cumulated phacoemulsification time and endothelial cell loss, perfect centration of the capsulotomy, and the possibility to perform precise femtosecond-assisted arcuate keratotomy incisions. The major disadvantages of FLACS are: high cost of the laser and the disposables for surgery, FLACS-specific intraoperative capsular complications, as well as the risk of intraoperative miosis and the learning curve. Conclusions: FLACS seems to be beneficial in some groups of patients i.e., with low baseline endothelial cell count, or those planning to receive multifocal intraocular lenses. Nevertheless, having considered that the advantages of FLACS might not be clear in every routine case, it cannot be considered as cost-effective.

Purpose To compare the lens tilt after apex-centered capsulotomy with standard pupil-centered capsulotomy. Setting Clinical practice. Design Prospective, randomized, investigator-masked trial. Methods This prospective, randomized, investigator masked study included 40 patients with age-related cataract scheduled for femtosecond laser-assisted cataract surgery (FLACS) in both eyes. The main outcome was the tilt of the intraocular lens (IOL), measured with the IOLMaster 700. Results The study enrolled 80 eyes of 40 patients. The mean distance from the center of the apex-centered capsulotomy to the pupil-centered capsulotomy was 175.8 ± 97.2 μm. The amount of IOL tilt was not significantly reduced with the new technique (P > .05). Tilt orientation was more stable in eyes treated with apex-centered capsulotomy. Conclusions Centration of the capsulotomy on the lens apex in FLACS does not influence the amount of IOL tilt but the orientation stability. The clinical importance of this finding has to be further elucidated.

The polarizing light microscope (PLM) is one of the most versatile tools in the laboratory, permitting the analyst to characterize and identify a very large variety of different materials in addition to determining crystalline polymorphs. Most research-grade PLMs allow various adjustments to align the microscope for centration of components to the optical axis. The Olympus BHSP PLM allows three of the four objective mounts in the rotating objective nosepiece to be centered by using two custom centering wrenches that are supplied with the microscope when purchased new. The same wrenches are additionally used to adjust centering of the stage. Over time, the wrenches can become lost or misplaced, and the wrenches are rarely provided with the sale of a used BHSP microscope. Replacement centering wrenches are often needed. Appropriately sized jeweler's screwdrivers can be used, but these do not remain in place and attached to the nosepiece or stage centering screws while focusing or manipulating other parts of the microscope during the centration procedure. This article provides steps in making suitable replacement centering wrenches.

Purpose to evaluate the effects of kappa angle and intraocular orientation on the theoretical performance of asymmetric multifocal intraocular lenses (MIOL). Methods For a total of 21 corneal aberrations, a computational analysis simulated the implantation of a computationally designed MIOL. An image quality parameter (IQ) (visually modulated transfer function metric) was calculated for a 5.0-mm pupil and for three conditions: distance, intermediate, and near vision. The procedure was repeated for each eye after a rotation of the MIOL with respect to the cornea from 0o to 360o in 5o steps. Kappa angles from 0 to 900 microns, in 150 microns steps, combined with two two variants of MIOL centration were tested: in the corneal apex or in the center of the entrance pupil. A p-value ≤ 0.05 was considered significant. Results There were statistically significant differences of the IQ depending of the intraocular orientation of the MIOL. If kappa angle was increased, there was a statistically significant decrease of the IQ. The IQ maintained stable when the optimal intraocular orientation was re-calculated for each kappa angle. In general, the inter-variability of the results between subjects was very high. There were no strong evidences supporting that there exists a preferable centration point. Conclusions Our results suggest that kappa angle theoretically affects significantly the performance of asymmetric MIOL implantation. However, its negative effect can be compensated if a customized intraocular orientation is calculated taking into account the presence of the kappa angle.

AIM: To compare the difference of capsulotomy produced by precision pulse capsulotomy (PPC), manual (M-CCC), and femtosecond laser assisted capsulotomy (FLAC) in relation to intraocular lens (IOL) centration, circularity and its effect on visual outcomes. METHODS: Prospective, non-randomized comparative study conducted at LV Prasad Eye Institute, Hyderabad, India. Sixty eyes of 52 patients were grouped into 3 (FLAC, PPC and M-CCC) based on capsulotomy techniques used. Twenty consecutive eyes with uneventful phacoemulsification and with no comorbidities affecting the capsulotomy or visual outcome were included in each group. The main outcome measure was IOL centration in relation to capsulotomy and pupil. Secondary outcome measures were post-operative visual acuity, manifest refraction and aberration profile between groups. RESULTS: At 5wk the visual, refractive outcomes and endothelial cell density were comparable between the 3 groups. The median circularity index of FLAC was statistically significantly different to M-CCC or PPC (1-10) groups (P

In this work, we demonstrate that microtubule asters are able to center in a variety of cell geometries and can do so over long distances, even when the activity of cytoplasmic dynein is inhibited. This observation, along with additional characterizations of aster movements, is consistent with a microtubule-based pushing mechanism.

To investigate the effect of lens centre thickness (and mass) upon short-term horizontal and vertical scleral lens decentration, and the association between both scleral topography and apical clearance, with lens decentration.Lens decentration was measured using over-topography data from 9 healthy young participants (25 ± 4 years) with normal corneae fitted with ICD 16.5 scleral lenses (hexafocon B material) with centre thicknesses of 150, 250, and 350 μm, while controlling for other lens parameters. Scleral toricity and elevation were determined from sagittal height data over a 15 mm chord obtained from a corneo-scleral topographer and central apical clearance was quantified using anterior segment optical coherence tomography.The mean lens decentration was 0.55 ± 0.19 mm temporally and 0.84 ± 0.35 mm inferiorly, which did not vary significantly with centre thickness (p 0.05). The mean nasal-temporal asymmetry in scleral elevation data was substantially greater (619 ± 67 μm) compared to the vertical meridian (369 ± 57 μm) (p 0.01), and this variation in scleral topography along the horizontal meridian was associated with the magnitude of horizontal lens decentration (r = 0.68, p = 0.04). Greater initial central apical clearance was associated with more inferior lens decentration (r = -0.78, p = 0.01).Lens centre thickness and mass did not significantly influence centration. Horizontal lens decentration was associated with the nasal-temporal asymmetry in scleral elevation, while vertical lens decentration correlated with initial central apical clearance. Factors affecting scleral lens centration may vary between the horizontal and vertical meridians.

Introduction Femtosecond laser-assisted cataract surgery (FLACS) has been considered a technological advance in modern cataract surgery. After years of experience, it has been observed that clinical outcomes had more complications than expected at the beginning. The aim of this study is to compare the benefits and disadvantages of the FLACS technique with conventional cataract surgery. Method The PubMed and Web of Science platforms were used to search for scientific literature. Results The femtosecond laser has currently improved the surgical technique in terms of the shorter ultrasound time used and the lower loss of endothelial cells. Likewise, the centration of capsulotomy and the correction of astigmatism with arcuate incisions have also been improved. As disadvantages, are the high cost of the laser, the intraoperative capsular complications, the induction of intraoperative myosis, and the learning curve of the technique. Conclusions The FLACS technique is considered beneficial for specific cases, such as patients with scheduled premium surgery, or with low endothelial cell count. However, it is believed that given the technological cost it is not a cost effective technique for most standard cases in our daily clinical practice.

PURPOSE: To describe the use of topography-guided custom ablation treatment with photorefractive keratectomy (T-CAT PRK) to correct irregular astigmatism and visual aberrations resulting from decentered small incision lenticule extraction (SMILE). METHODS: Case report and literature review. RESULTS: A 41-year-old woman experienced blurred uncorrected distance acuity (UDVA), reduced corrected distance acuity (CDVA), and monocular diplopia in one eye following SMILE due to treatment decentration. Retrospective review of the surgical video provided visual cues to the impending decentration at multiple points during the docking process and lenticule creation. Re-treatment was performed using T-CAT PRK with mitomycin C application with off-label use of the EX500 excimer laser (Alcon Laboratories, Inc). Treatment resulted in improvement in UDVA and CDVA to 20/12; reduced higher order aberrations, particularly vertical coma (−0.65 µm to 0.197 µm); topographic pattern centration; and subjective symptom resolution. CONCLUSION: Recognition of subtle visual cues at the time of SMILE docking can provide critical feedback to avoid treatment decentration. T-CAT PRK can be a useful treatment option when decentration occurs. [ J Refract Surg . 2020;36(11):766–771.]

Introduction To determine if intraoperative manual centration of the intraocular lens (IOL) during cataract surgery results in better early post-operative centration. It is common practice for cataract surgeons to align intraocular lens centration to the visual axis by manual intraoperative manipulation of the intraocular lens. We aim to compare post-operative intraocular lens centration between intraocular lenses that were allowed spontaneous positioning in the capsular bag and IOLs that were manually centred during implantation. Materials and Methods One hundred and twenty-five consecutive eyes that underwent either femtosecond laser-assisted cataract surgery (FLACS) or phacoemulsification and IOL (monofocal/toric/multifocal) implantation by a single surgeon were included. Post-operative IOL centration at 4 weeks was assessed and measured on a slit-lamp by a masked observer. Results A total of 17 (13.6%) IOLs were off-centered to some extent at 4 weeks post-operatively. All the decentered IOLs were graded as minimal or mild (

Purpose To evaluate overall patient satisfaction, spectacle independence, binocular visual acuity, rotational stability, prevalence of optical phenomena, and decentration and tilt after bilateral toric extended depth-of-focus intraocular lens (EDOF IOL) implantation targeted for micromonovision. Setting Department of Ophthalmology, Hanusch Hospital, Vienna, Austria. Design Prospective case series. Methods The study included 52 eyes of 26 patients with regular corneal astigmatism from 0.75 to 2.60 diopters (D) that were implanted bilaterally with a toric EDOF IOL targeted for micromonovision. Postoperative visual acuity, astigmatism reduction, rotation, tilt, decentration, spectacle independence, patient satisfaction, and photic phenomena were assessed. Results For the 52 eyes studied, binocular means expressed in logarithm of the minimum angle resolution for postoperative corrected distance, uncorrected distance, uncorrected intermediate, and uncorrected near visual acuities were -0.10 (±0.12), -0.01 (±0.13), 0.01 (±0.14), and 0.13 (±0.14), respectively. Mean refractive astigmatism reduction was 1.31 ± 0.67 D resulting in a mean refractive cylinder of 0.47 ± 0.46 D at the 3-month visit. Mean postoperative rotation was 3.5 ± 3.5 degrees, at the 3-month time point. Most prevalent dysphotopsia were halos, starburst, and glare affecting 6 (23%), 6 (23%), and 5 (19%) of 26 patients, respectively; 20 (77%) of 26 patients reported spectacle independence, with 19 (95%), 19 (95%), and 14 (70%) of 20 patients questioned being satisfied with distance, intermediate, and near vision, respectively. Conclusions Toric EDOF IOL implantation targeted for micromonovision resulted in reliable reduction of preoperative astigmatism with a high degree of postoperative rotational predictability and centration, enabling functional distance, intermediate, and near vision, which manifested itself in high patient satisfaction.

To compare the visual and refractive outcomes between centration on the corneal vertex and the pupil center in corneal refractive surgery. A comprehensive literature search was conducted using PubMed, MEDLINE, EMBASE, and the Cochrane Library to identify relevant studies. The primary outcomes were the postoperative spherical equivalent (SE), effectiveness [uncorrected distance visual acuity (UDVA) ≥ 20/20, eyes within ± 0.50 diopter (D) of target refraction], and safety [loss ≥ 2 lines of corrected distance visual acuity (CDVA)]. Higher-order aberrations were considered secondary outcomes. Seven studies describing a total of 1964 eyes were included in this meta-analysis. A statistical significance in postoperative SE was found between the two centration methods for the correction of myopia that favor the CV-centered method (p

PURPOSE To evaluate the safety, efficacy, and on-eye performance of new-generation hybrid contact lenses (HCLs) in visual rehabilitation of eyes with irregular astigmatism and rigid gas-permeable (RGP) contact lens intolerance or failure. METHODS The charts of patients who had been fit with new-generation HCLs were retrospectively reviewed. The reason for HCL fit and previous method of correction were noted. After the initial on-eye evaluation, visual and refractive outcomes, slit-lamp biomicroscopy, and lens comfort were evaluated at the last follow-up examination. RESULTS Forty-seven eyes of 33 patients could be fit successfully with EyeBrid silicone (LCS, Cane, France) or Airflex (SwissLens, Prilly, Switzerland) lenses. The mean number of trial lenses required for ideal fit was 1.4±0.6 (range; 1-3) lenses. The reason for fit was either centration problems with RGP lenses or RGP intolerance. Twenty-nine eyes of 20 patients (72.5%) continued wearing their lenses more than 10 hr a day and for more than 3 months. In these successful wearers, the visual acuity (VA) improved significantly compared with the baseline uncorrected and spectacle-corrected VA (P

Increasing demands in imaging quality of all assembled optical systems require the optimization of lateral and axial alignment of individual lenses. An economic possibility to improve mechanical alignment is the step-by-step centration testing of the topmost lens surface during the assembly process. Regardless of the material properties of the lens, measurement equipment that operates in the visible spectral range is suitable for this application. When the assembled lens does not meet the expected imaging performance, an in-depth analysis is needed. Focusing electronic autocollimators in combination with high-precision air bearing spindles are commonly used to analyze the centration of each optical surface and lens element. The well-established TRIOPTICS OptiCentric family allows to determine the centration of inner surfaces using their powerful MultiLens technique. The obtained measurement data are processed to provide the shift and tilt of individual lenses or groups of lenses with respect to each other or a freely selectable datum. For IR lenses a wavelength that can penetrate the lens material is required. Autocollimators for MWIR or LWIR are to be combined with a VIS measurement head for all measurements on lens surfaces that are directly accessible from the outside. A measurement accuracy of 0.1μm is reached. The development of the new OptiCentric® IR autocollimation head, was mainly driven by optimizing the spot size and hence its accuracy. A centration measurement precision of below 0.25 micrometer for MWIR and LWIR wavelengths was obtained. For measurement of air spacings and center thicknesses through all IR lens materials the instrument incorporates a low coherence interferometer with an accuracy down to 0.15µm. The contribution describes how an IR lens assembly consisting of several lenses can be fully opto-mechanically characterized in a non-contact and non-destructive fashion. Optimized processes to effectively streamline processes are taken into consideration same as prerequisites like operator skills.

Author(s): Bever, Gregory J; Liu, Yingna; Stewart, Jay M | Abstract: PurposeTo describe a modified technique of haptic externalization for trocar-based sutureless scleral fixation of intraocular lenses, in order to avoid working with forceps in the iris plane in a manner that may be unfamiliar to the vitreoretinal surgeon.MethodsThis prospective, interventional case series included four eyes of four patients with dislocated intraocular lens (IOL). The modified haptic externalization technique avoids the pitfalls of iris-plane maneuvers by intentionally dropping the IOL onto the retina and using the forceps to grasp the tips of the haptics prior to direct externalization from the same grab.ResultsFour patients underwent scleral fixation of IOL using modified haptic externalization technique. One patient was lost to follow up after postoperative day 1. At the last follow up, all eyes demonstrated stability and good centration of scleral fixated IOL. All three patients achieved a best corrected visual acuity same or better compared to before the operation. One patient developed vitreous hemorrhage which later spontaneously resolved.ConclusionsThe modified haptic externalization technique is a simple and quick modification using maneuvers familiar to vitreoretinal surgeons. It has demonstrated safety among a small pilot group of patients.

Posterior dislocation of the intraocular lens (IOL) is a rare but potentially dangerous complication encountered by a cataract surgeon. We describe a modified balanced two-string technique of internally fixing a posteriorly dislocated rigid IOL using the pars plana approach in eyes which lack adequate capsular support. Five eyes of five patients underwent the procedure. All eyes had successful IOL refixation. One eye had mild temporal decentration. BCVA improved in all patients. Our technique is an alternate method of scleral fixation of posteriorly dislocated IOL with advantages of minimal postoperative astigmatism, minimal anterior segment manipulation, and good IOL centration.

The authors present their experience with an innovative model of scleral-fixated intraocular lens (SFIOL): the CM-T Flex intraocular lens (IOL). By its unique design, the CM-T Flex IOL simplifies the process of SFIOL fixation by limiting the process to simply exteriorizing and releasing the haptic. This retrospective cohort study included nine eyes with surgical aphakia. The CM-T Flex IOL was used in these nine aphakic eyes that had completed a 3-month follow-up. Improvement in visual acuity (0.34 ± 0.25 logMAR [range: 0.2 to 1] to 0.22 ± 0.32 logMAR [range: 0 to 0.77]) was recorded with no major complications. IOL stability and centration was established. The authors concluded that the CM-T Flex IOL was effective for refractive rehabilitation in aphakic eyes. [ Ophthalmic Surg Lasers Imaging Retina. 2020;51:648–650.]

PURPOSE To describe a method to center a Descemet stripping automated endothelial keratoplasty lamellar graft and address interface folds. METHODS A novel technique to center a Descemet stripping automated endothelial keratoplasty graft without undue manipulation of endothelial surface using a STC-6 needle passed obliquely through the anterior corneal surface to engage and progress the lenticule along the posterior surface after injection of air. RESULT Centration of graft achieved and macroscopic folds resolved. CONCLUSIONS Here, we describe an atraumatic and reproducible method for graft centration.

We describe a surgical technique for fine-tuning the centration of a transscleral-sutured modified capsular tension ring (CTR)-intraocular lens-capsular bag complex using a partial-thickness scleral tethering suture placed posterior to the external episcleral portion of a transscleral suture loop. The technique can be used for adjusting the centration of any intraocular supporting or prosthetic device that is transsclerally sutured in a "hanging" technique, such as capsular tension segments, modified CTRs, capsular anchoring devices, or iris prostheses.

This article reviews the current techniques and emerging devices for the creation of an anterior capsulotomy. Manual continuous curvilinear capsulorhexis (CCC) remains the most widely used technique and physical tools have been introduced and adopted by surgeons as guides to improve the precision of the manual CCC. Femtosecond-assisted capsulotomy has had moderate adoption by surgeons due to lack of clear evidence demonstrating superior outcomes, cost, and compromised surgical efficiency. However, quick, precise, and reproducible capsulotomies continue to be sought after and several automated devices have and will be introduced. Manually creating the anterior capsulorhexis remains the gold standard because of efficiency and cost but consistent outcomes require significant experience and technical skill. New automated technologies aim to provide the desired consistency and precision with visual axis centration without compromising surgical workflow. These technologies show promise and may yield superior visual and refractive outcomes but research will be valuable for evaluating these devices.

The advent of “flapless” small-incision lenticule extraction (SMILE), employing all-in-one technology, has resulted in a revolutionary breakthrough in refractive surgeries. SMILE has been gaining popularity due to fewer potential complications, such as postoperative dry eyes and greater biomechanical stability, etc. However, attention must be given to 1) the centration on the corneal vertex, 2) the proper alignment of the astigmatic axis, and 3) the relationship between pupil size and treatment diameter, to achieve good SMILE results. There is no pupil-tracking system to ascertain the accuracy of centration during the SMILE surgery. To improve the centration accuracy, our center uses two corneal topographers (Pentacam and Sirius) to measure and determine corneal vertex. Proper predicted optical zone diameter is not clearly defined yet in SMILE. Some scholars insist that mesopic pupil size should be taken into consideration when setting the predicted optical zone. Meanwhile, the issue of “functional optical zone” still has many unresolved issues and warrants further studies.