Acrylic Intraocular Lens Research Articles

Visual outcomes following high water-content hydrophobic acrylic trifocal intraocular lens implantation

BackgroundTo prospectively evaluate binocular visual outcomes after implantation of trifocal intraocular lenses (IOLs) with high-water-content hydrophobic acrylic material in Japanese patients.MethodsIn 59 patients (mean age 65.1 ± 7.9 years), Clareon PanOptix (CNWTT0: Alcon) with a high-water-content hydrophobic acrylic material was implanted bilaterally. Three months postoperatively, binocular uncorrected visual acuity (BUCVA) and distance-corrected visual acuity (BDCVA) at distances of 5 m, 80, 60, and 40 cm, binocular defocus curves, and binocular photopic contrast sensitivity were examined. Subjective symptoms (night vision disturbance, glare, halos, haze, or blurry vision) were also assessed.ResultsThe mean postoperative BUCVA/BDCVA at 5 m, 80 cm, 60 cm, and 40 cm were − 0.115/-0.163, -0.052/-0.047, -0.054/-0.075, and − 0.043/-0.067 logMAR, respectively. A smooth defocus curve, contrast sensitivity within the normal range, and acceptable subjective symptom rates were obtained.ConclusionsThe trifocal IOL, composed of a high-water-content hydrophobic acrylic material, provides good continuous binocular vision from distance to near.Trial registrationThis investigator-initiated study was registered in the Japan Registry for Clinical Trials (identifier: jRCTs032220042) on April 26, 2022.

Effect of Hydrophobic Acrylic Monomers with Different Alkyl Side Chain Lengths on Reducing the Glistening of Hydrophobic Acrylic Intraocular Lens Materials

AbstractGlistening is the condensation of water that forms within the intraocular lens (IOL) materials. In this study, a new approach was attempted to reduce the glistening of IOL materials by introducing hydrophobic acrylic monomers with different alkyl side chain lengths into the IOL materials. Various hydrophobic acrylic monomers such as butyl acrylate (BA), 2‐ethylhexyl acrylate (EHA), and dodecyl acrylate (DA) were copolymerized with a hydrophobic acrylic monomer, 2‐phenoxyethyl acrylate, respectively. In this process, we investigated the effect of the alkyl side chain lengths of hydrophobic acrylic monomers on the glistening of hydrophobic acrylic IOL materials. As the content of hydrophobic acrylic monomers (BA, EHA, and DA) increased, the glistening of IOL materials decreased significantly for all hydrophobic acrylic monomers. At the same content of hydrophobic acrylic monomers, the IOL material showed the least content of glistening when copolymerized with DA. However, the IOL material obtained using BA exhibited the largest content of glistening, indicating that the glistening reduction effect was large in the order of DA>EHA>BA. These findings show that the glistening of IOL materials decreases with increasing alkyl side chain lengths of hydrophobic acrylic monomers.

Late Subluxation of Intraocular Lens Due to Haptic-Optic Adhesion

This case report describes a rare instance of late subluxation of an Intraocular Lens (IOL) resulting from adhesion between the haptic and optic components. Intraocular lens subluxation is typically associated with zonular weakness, trauma or capsular bag contracture; however, this case underscores an uncommon etiology related to adhesion between the haptic tip and the optic in a one piece hydrophobic acrylic IOL. This report highlights the clinical presentation, surgical management and implications for patient care, contributing to the understanding of long-term complications in cataract surgery.

DIFFUSE PUNCTATE DEPOSITS ON THE SURFACE OF HYDROPHILIC ACRYLIC INTRAOCULAR LENSES EARLY POSTOPERATIVELY: CASE SERIES AND LABORATORIAL ANALYSES

Purpose: To describe cases of hydrophilic acrylic intraocular lenses (IOLs) (Eyecryl, Biotech) exhibiting surface punctate deposits early postoperatively, and provide laboratorial analyses of unused lenses of the same model. Setting: Altino Ventura Foundation (FAV), Recife, Brazil, and John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. Design: Observational, descriptive, clinical study with laboratorial analysis. Methods: A thorough review of records of patients undergoing phacoemulsification with Eyecryl implantation in December 2022 at FAV was performed, with data collection. Five Eyecryl IOLs (never implanted/unused) were removed from the original package and underwent gross examination, light microscopy, and ultrastructural analyses using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Results: Details on 5 clinical cases exhibiting surface IOL deposits on the first postoperative day after uneventful surgery, and followed for at least 6 months were included. The deposits disappeared by the 60th postoperative day. No inflammatory or toxic reactions were noted, visual outcomes were favorable, and IOL explantation was not necessary. Three of the 5 unused lenses undergoing laboratorial analyses revealed diffuse, star-like shaped deposits that could not be removed by thorough irrigation with distilled water. SEM/EDS revealed a composition of the deposits that primarily consisted of carbon and oxygen. Conclusion: Laboratorial findings suggest the etiology of the deposits might be related to the manufacturing/packaging process of lenses from specific lots. While the deposits did not appear to be associated with inflammatory or toxic reactions in the clinical cases, further investigations are necessary to elucidate their precise origin.

A study to compare the prevalence of posterior capsular opacity between patients implanted with hydrophobic acrylic intra ocular lens (IOL) versus hydrophilic acrylic intra ocular lens (IOL) in the diabetic and non-diabetic group following cataract surgery: A hospital based prospective study

: To study and compare the prevalence of posterior capsular opacity between patients implanted with hydrophobic acrylic IOL versus hydrophilic acrylic IOL in the diabetic and non diabetic group following cataract surgery. All patients with senile cataracts, whether they had diabetes or not, who visited a tertiary care hospital in Tamil Nadu between 2020 and 2022 were enrolled in this study after signing a written consent form. In this study, 200 patients underwent screening and were split into 4 equal groups.The PCO observation of patients in all 4 groups in the current study showed that Groups 3 and 4 with hydrophilic IOL found higher incidences of PCO than Groups 1 and 2 with hydrophobic IOL. In our study, more PCO was reported with hydrophilic IOL with known (Group 3) and unknown (Group 4) cases of diabetes. Regardless of the patient's level of diabetes during the course of a year-long follow-up, hydrophobic acrylic IOLs showed a greater decrease in PCO rates than hydrophilic acrylic IOLs.

SING IMT removal for unsatisfied patients: step-by-step surgery for a safe explant.

To report three cases of Smaller-Incision New-Generation Implantable Miniature Telescope (SING-IMG) explantation and three-piece acrylic intraocular lens (IOL) implantation in patients affected by late-stage dry AMD. This is a single-center cohort study. Three patients with stable dry AMD previously implanted with SING-IMT failed to adapt to the device requesting its explantation. Surgical procedures were performed under peribulbar anesthesia, with careful removal of the SING-IMT telescope through a sclero-corneal tunnel of 8 mm and implantation of a three-piece acrylic IOL. Patients underwent pre and postoperative assessments, including visual acuity measurements, endothelial cell count and intraocular pressure. Patients were followed postoperatively for at least 6 months, with particular attention to IOL stability and posterior capsule integrity. Postoperative assessments demonstrated positive outcomes, revealing no IOL dislocation or posterior capsular opacification after 6 months. Endothelial cell count diminished. Best-corrected visual acuity (BCVA) returned to values before SING-IMT implantation. In our small cohort, SING-IMT explantation appeared to be a safe option. Despite promising visual outcomes, some patients might not adapt to SING-IMT. Further studies are needed to evaluate criteria to predict telescope adaptation.

Examining Penetration and Residual Depth in Modern Acrylic Foldable Intraocular Lenses: A Laboratory Study Using Differential Interference Contrast Microscopy to Compare Hydrophilic and Hydrophobic Materials.

Introduction The material of modern intraocular lenses must meet the highest standards and fulfill various requirements. It is crucial that the material shows the best biocompatibility and should be flexible for an uncomplicated implantation process through small corneal incisions but also sufficiently rigid for good stability and centering in the capsular bag. In addition, the optic must remain clear for life and retain the best optical properties. Methods In this laboratory experiment, we performed scratch tests for the mechanical assessment of acrylic intraocular lenses. The aim was to determine differences in the behavior in regard to the manufacturing process and water content of hydrophilic and hydrophobic acrylic intraocular lenses. The scratch tests were performed using a Nano Scratch Tester. A conical indenter with a tip radius of 1 µm and a cone angle of 90° was selected to scratch the samples at three different constant loads of 5, 10, and 15 mN, respectively. The scratch length was set to 100 µm at a scratch speed of 200 µm/min. Hydrophilic and hydrophobic acrylic intraocular lenses (with different water content) were tested. Results The results showed that for sample A (hydrophilic acrylate), the penetration depth increases steadily with increasing force from 25-30 µm (5 mN) to 28-33 µm (10 mN) and 34-37 µm (15 mN). The penetration depths during the scratches seem to be load-dependent. In sample B (hydrophobic acrylate), the same forces lead to steadily increasing penetration depths: 25-30 µm (5 mN), 40-44 µm (10 mN), and 54-57 µm (15 mN). The evaluation of the residual depth showed much lower values for all samples. In the hydrophilic, softer samples (A), the residual depth was between 1 µm and 4 µm. In the hydrophobic, more solid, samples (B), the residual depth was more pronounced with values between 5 µm and 17 µm. The plastic influence and deformation zone seemed to be wider for the hydrophobic samples than for the hydrophilic samples. Conclusion The laboratory experiment confirms that modern, acrylic intraocular lenses are sensitive to scratches/touch, and penetration depths during scratching depend on the load. The remaining depths after the scratches are significantly lower and show a load dependence. The deforming zone was higher in the hydrophobic acrylates than in the hydrophilic acrylates. However, the results confirm that damage can occur with hydrophobic and hydrophilic acrylic materials, depending on the force applied. Therefore, careful handling during the preparation and implantation process is crucial to prevent permanent defects.

Comparison of Pacman cutting technique and trisection cutting technique for hydrophobic acrylic intraocular lens removal.

The objective of this retrospective cohort study is to compare the Pacman cutting technique with the trisection cutting technique for hydrophobic acrylic intraocular lens extraction. A total of 29 eyes of 29 patients requiring IOL removal were selected and enrolled in this study. The patients in group 1 (13 cases) underwent the conventional trisection cut technique from May 2022 to Dec. 2022. The patients in group 2 (16 cases) underwent the modified partial IOL cutting technique (Pacman cutting technique) from Jan. 2023 to June 2023. Corneal endothelial cells (CECs) count, slit-lamp examination, and intraocular pressure (IOP) measurement were conducted at all preoperative and postoperative visits. Surgical time, intraoperative and postoperative complications were recorded. The mean surgical time was 3.48 ± 1.54 minutes (range: 2 to 7 minutes) for the trisection cut technique group and 2.52 ± 1.18 minutes (range: 2 to 5 minutes) for the Pacman cut technique group. There was a statistically significant difference between the two groups in terms of surgical duration (P < .05). There was no difference in the mean preoperative CEC counts (group 1: 1924 ± 462, group 2: 1876 ± 516, P > 0.05). However, three months after the operation, the count of CECs decreased by 213 ± 72 (11%) in group 1 and 142 ± 57 (8%) in group 2. The decrease in CECs in group 1 was greater than that in group 2, and the difference was statistically significant (P < .05). There were no serious complications affecting vision in either group during the follow-up period. This study showed that the Pacman cutting technique is more effective and safer than the trisection cutting technique for hydrophobic acrylic IOL removal.

Image Contrast and Spectral Transmission of Presbyopia-Correcting Intraocular Lenses: Evaluating the Impact of Nd:YAG Laser Associated Defects

Purpose Neodymium yttrium aluminum garnet (Nd:YAG) laser capsulotomy is considered gold standard in the treatment of posterior capsule opacification (PCO). In this laboratory study, we measured spectral transmission to evaluate the image contrast and analyze the impact of Nd:YAG associated defects in presbyopia-correcting intraocular lenses (IOLs). Methods Two hydrophobic, acrylic IOLs as classic multifocal lenses with diffractive ring segments and different amount of near addition (A, B), one hydrophilic, trifocal IOL (C), one sector-shaped, plate haptic IOL (D) and one hydrophobic, enhanced depth of focus (EDOF) IOL (E) were studied. Measurements included surface topography characterization, United States Air Force resolution test chart (USAF) analysis, spectral transmittance measurements and through focus contrast measurement. Measurements were done with unaltered samples, damages (n = 7) were intentionally created in the central 3.5 mm zone using a photodisruption laser (2.0 mJ) and measurements were repeated. Results Significant differences were shown between unmodified samples and samples with YAG pits. The YAG-pits decreased the image contrast and spectral transmission and changed results of USAF test images. The imaging contrast decreased to 66%, 64%, 60%, 52% and 59% with the YAG shots in samples (A-E). The light transmission decreased to 88%, 87%, 92%, 79% and 91% (A-E) on average between 400 nm to 800 nm. In all IOLs a reduction of the relative intensity of transmitted light was observed. Conclusion The image performance of all tested presbyopia-correcting IOLs is significantly influenced and disturbed by YAG-pits. The intensity of transmitted light is reduced in the wavelength between 450–800 nm. USAF test targets show worse results compared to unmodified samples and contrast is significantly deteriorated. No ranking/rating among tested IOLs should be made as many other factors play a role in real world scenario. High care should be taken when performing Nd:YAG capsulotomy on premium IOLs to avoid any damages.

Posterior capsule opacification with two similar-design hydrophobic acrylic intraocular lenses: 3-year results of a randomized controlled trial.

To compare intraindividually the incidence and intensity of posterior capsule opacification (PCO) and Nd:YAG capsulotomy rates between two similar open-loop single-piece hydrophobic acrylic intraocular lenses (IOLs) differing slightly in their particular material, optic surface and sharp posterior edge design over a period of 3 years. Department of Opthalmology, Medical University Vienna. Randomized, prospective, patient- and examiner-masked clinical trial with intraindividual comparison. 100 patients randomly received a Vivinex XY1 IOL in one eye and a Clareon CNA0T0 IOL in the fellow eye. The amount of PCO (score: 0 - 10) was assessed subjectively and objectively with digital retroillumination picturs using automated image analysis software (AQUA). Best-corrected distance visual acuity (CDVA) as well as the presence of glistenings, subjective visual symptoms and Nd:YAG laser capsulotomy rate were noted. 67 of 100 patients were available for the 3-years follow-up examination. The objective PCO score of the Vivinex XY1 IOLs was 1.0 ± 1.0 compared to the PCO score of 1.5 ± 1.2 for the Clareon CNA0T0 IOLs (p < 0.001). 7.5% of patients had a neodymium:yttrium-aluminium-garnet (Nd:YAG) capsulotomy in the Vivinex XY1 eye, and 9.0% had a capsulotomy in the Clareon CNA0T0 eye (p = 1.0). Both hydrophobic acrylic IOLs showed low PCO and YAG rates with a small but significant favor of the Vivinex XY1 IOL compared to the Clareon CNA0T0 IOL. The interaction of various factors such as hydrophobic material, smooth optic surface and sharp posterior optic edge is the major key for PCO prevention.

A study of contrast sensitivity in eyes with hydrophobic and hydrophilic acrylic foldable posterior chamber intraocular lens

A study of contrast sensitivity in eyes with hydrophobic and hydrophilic acrylic foldable posterior chamber intraocular lens

A clinical study of the neodymium-doped yttrium–aluminium–garnet laser posterior capsulotomy: Visual outcome and early complications

Objectives: The objectives of this study were as follows: To study the efficacy of neodymium-doped yttrium–aluminium–garnet (Nd:YAG) laser capsulotomy in posterior capsular opacification (PCO) by analysing the visual outcome. To study any other early complications seen following Nd:YAG laser capsulotomy. Materials and Methods: A prospective interventional study was done in the Department of Ophthalmology of a tertiary care hospital in the Marathwada region of Maharashtra. A total of 55 eyes developing PCO after cataract surgery were included in the study from November 2022 to October 2023. Routine pre-laser evaluation using slit-lamp biomicroscopy, intraocular pressure (IOP) measurements and dilated fundus examination was done. Thirty-eight patients had undergone manual small incision cataract surgery with polymethyl methacrylate intraocular lens (IOL) implantation and 17 patients had undergone phacoemulsification surgery with acrylic foldable IOL implantation. The patient was then followed up on Days 2, 7, 30, and 3 months to look for any early post-laser complications. Results: A total of 55 eyes were included in the study. The age group of patients included in the study is from 50 to 75 years. Most of the patients 21 were in the age group of 56–60 years. Twenty (36%) were male and 35(63%) females; thus, female preponderance is seen. On retro-illumination of the slit lamp, 9 (16.3%) patients had severe PCO having vision ≤3/60, 24 (43.6%) patients had moderate PCO with vision 3/60–6/60 and 22 (40%) patients had mild PCO with vision 6/60–6/18. Forty-seven patients (85%) had visual acuity of more than 6/12 at the end of 3 months. In most patients, an appropriate central capsulotomy was achieved within the total energy of 60 mJ but in three cases more than 100 mJ energy was used due to the thick posterior capsule. About 6% of subjects showed increased IOP of more than 21 mm Hg but returned to normal level within 1 week. Mild uveal reaction in the form of anterior chamber flare and cells was seen in 2% of cases. IOL pitting was seen in 5 (8%) cases. One (2%) patient had a vision of 3/60 and a significant increase in macular thickness at day 7 post-laser which decreased at 1 month follow-up by appropriate treatment. No evidence of any retinal tears or retinal detachment seen. Conclusion: PCO is a common delayed complication seen after cataract surgery. This opacification decreases the vision of the patient to affect day-to-day activities. It can be easily managed on an outdoor basis by a non-invasive and effective Nd:YAG laser posterior capsulotomy procedure. This procedure has been shown to increase the visual outcome and has fewer complications which can be managed easily.

Rotational stability and refractive outcomes of a new hydrophobic acrylic toric intraocular lens

PurposeTo assess rotational stability and refractive outcomes of a new toric hydrophobic acrylic intraocular lens (IOL).DesignSingle-center, prospective, interventional clinical trial.MethodsA total of 130 eyes of 82 patients with age-related cataract and total corneal astigmatism of greater than 1.0 diopters (D) received a hydrophobic acrylic toric IOL Clareon CNW0T3-9. Baseline measurement for rotational stability evaluation was performed at the end of surgery (EOS), with the patient still supine on the operating table, using non-movable vessels as reference landmarks. Postoperative retroillumination pictures were taken at 1 h, 1 week, 1 month and 4–6 months postoperatively. Subjective manifest refraction was assessed at the 6 months follow-up visit.ResultsFinal results were obtained in 126 eyes of 80 patients. Mean absolute rotation from EOS to 6 months was 1.33 ± 2.00 [0.01, 19.80] degrees. Rotational stability values from EOS to 1 h, 1 h to 1 week, 1 week to 1 month and 1 month to 6 months were 0.86 ± 0.82 [0.00, 3.90], 1.06 ± 1.94 [0.00, 19.45], 0.47 ± 0.42 [0.00, 2.03] and 0.38 ± 0.40 [0.00, 2.56] degrees. Mean preoperative corneal astigmatism was 1.78 ± 0.83 [1.00, 4.76] D which changed to a mean postoperative refractive astigmatism of 0.33 ± 0.27 [0.00, 1.25] D at 6 months.ConclusionThe Clareon toric IOL presented very good rotational stability with a mean absolute rotation below 1.4° from EOS to 6 months. Only two IOLs rotated more than 5° with none of them requiring repositioning surgery. Refractive outcomes were satisfying with a mean residual refractive astigmatism below 0.50 D.Trial registrationRegistered at Clinicaltrials.gov NCT03803852; on May 17, 2022.

Visual axis reopacification after Nd:YAG laser posterior capsulotomy

Posterior capsular opacification (PCO) and anterior hyaloid face opacification are the two possible causes of visual axis opacification after cataract surgery, of which PCO is more common in adults. This is treated by neodymium-doped yttrium aluminum garnet (Nd:YAG) laser-assisted disruption of the opacified posterior capsule/membrane. Recurrence of visual axis opacification after a successful Nd:YAG laser posterior capsulotomy is infrequent. We report a case of visual axis reopacification after a successful Nd:YAG capsulotomy for PCO in an adult with no history of systemic or ocular disease who underwent phacoemulsification and an acrylic hydrophobic intraocular lens implantation. Patients should be explained about this possibility when undergoing Nd:YAG capsulotomy.

Modified "C" Haptic Intraocular Lens Orientation and Negative Dysphotopsia.

Phacoemulsification is the standard of care in cataract surgery in the developed world, with patients having high expectations regarding visual results. Postoperative dissatisfaction due to negative dysphotopsia (ND) ranges from rare to very frequent; its etiology is unclear, and it affects postoperative satisfaction. Since one of the most frequently used strategies to avoid ND is related to intraocular lens (IOL) haptic orientation, we conducted a prospective interventional study that enrolled 197 patients who underwent standard phacoemulsification. All patients had a one-piece hydrophobic acrylic IOL implanted; in one group, the haptics were placed in any meridional axis except inferotemporal (IT) meridians, and in the other group, the IOL was implanted with the haptics in an IT position. Our results showed no statistically significant differences between groups when analyzing the correlation between the position of IOL haptics and the presence of ND in week one and month one. Also, pupillary diameter showed no statistically significant differences between patients with or without ND. Despite some studies claiming that haptic orientation prevents ND, we found that haptic orientation does not correlate with ND incidence and that ND decreases from day 1 to month 1. Our results support previous findings on the decrease in ND over time and that haptic orientation should not be considered an intraoperative strategy to avoid this unwanted phenomenon.

Zwitterionic sulfobetaine methacrylate (SBMA) coating on hydrophobic acrylic intraocular lens material to prevent the adhesion of lens epithelial cells: Effect of SBMA concentration

Posterior capsular opacification (PCO), known as a prevalent complication of cataract surgery, occurs because of the attachment and abnormal proliferation of remaining lens epithelial cells (LECs) after cataract surgery. To reduce the PCO occurrence by improving cell adhesion resistance, we attempted zwitterionic sulfobetaine methacrylate (SBMA) coating through ultraviolet-induced graft polymerization on the surfaces of intraocular lens (IOL) materials. In this study, the effect of the concentration of SBMA monomers in the coating solutions adjusted from 10 wt% to 30 wt% was investigated on the chemical composition, morphology, and hydrophilicity of the IOL material surfaces modified with SBMA. Additionally, the effect of SBMA concentration on preventing adhesion to protein and LECs on the surfaces of SBMA-modified IOL materials was evaluated in vitro. Grafting of zwitterionic SBMA on the surfaces of hydrophobic acrylic IOL materials was confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and water contact angle (WCA). To evaluate the long-term hydrophilicity of coating films prepared with different concentrations of SBMA on the IOL material surfaces, the WCA of IOL materials stored in phosphate-buffered saline solution was measured as a function of time. The coating film prepared at a concentration of 20 wt% of SBMA showed the lowest WCA after 28 days, showing the best long-term hydrophilicity. Also, that prepared at a concentration of 20 wt% of SBMA exhibited the highest anti-adhesion effect on proteins and LECs.

A 3D in vitro model for assessing the influence of intraocular lens: Posterior lens capsule interactions on lens epithelial cell responses

Posterior Capsule Opacification (PCO), the most frequent complication of cataract surgery, is caused by the infiltration and proliferation of lens epithelial cells (LECs) at the interface between the intraocular lens (IOL) and posterior lens capsule (PLC). According to the “no space, no cells, no PCO” theory, high affinity (or adhesion force) between the IOL and PLC would decrease the IOL: PLC interface space, hinder LEC migration, and thus reduce PCO formation. To test this hypothesis, an in vitro hemisphere-shaped simulated PLC (sPLC) was made to mimic the human IOL: PLC physical interactions and to assess their influence on LEC responses. Three commercially available IOLs with different affinities/adhesion forces toward the sPLC, including Acrylic foldable IOL, Silicone IOL, and PMMA IOL, were used in this investigation. Using the system, the physical interactions between IOLs and sPLC were quantified by measuring the adhesion force and interface space using an adhesion force apparatus and Optical Coherence Tomography, respectively. Our data shows that high adhesion force and tight binding between IOL and sPLC contribute to a small interface space (or “no space”). By introducing LECs into the in vitro system, we found that, with small interface space, among all IOLs, acrylic foldable IOLs permitted the least extent of LEC infiltration, proliferation, and differentiation (or “no cells”). Further statistical analyses using clinical data revealed that weak LEC responses are associated with low clinical PCO incidence rates (or “no PCO”). The findings support that the in vitro system could simulate IOL: PLC interplays and predict IOLs’ PCO potential in support of the “no space, no cells, no PCO” hypothesis.

A Novel 3D High Resolution Imaging Method Using Correlative X-Ray and Electron Microscopy to Study Neodymium-Doped Yttrium Aluminum Garnet Laser-Induced Defects in Intraocular Lenses.

Cataract extraction is the most frequently performed ophthalmological procedure worldwide. Posterior capsule opacification remains the most common consequence after cataract surgery and can lead to deterioration of the visual performance with cloudy, blurred vision and halo, glare effects. Neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy is the gold standard treatment and a very effective, safe and fast procedure in removing the cloudy posterior capsule. Damaging the intraocular lens (IOL) during the treatment may occur due to wrong focus of the laser beam. These YAG-pits may lead to a permanent impairment of the visual quality. In an experimental study, we intentionally induced YAG pits in hydrophilic and hydrophobic acrylic IOLs using a photodisruption laser with 2.6 mJ. This experimental study established a novel 3D imaging method using correlative X-ray and scanning electron microscopy (SEM) to characterize these damages. By integrating the information obtained from both X-ray microscopy and SEM, a comprehensive picture of the materials structure and performance could be established. It could be revealed that although the exact same energies were used to all samples, the observed defects in the tested lenses showed severe differences in shape and depth. While YAG pits in hydrophilic samples range from 100 to 180 µm depth with a round shape tip, very sharp tipped defects up to 250 µm in depth were found in hydrophobic samples. In all samples, particles/fragments of the IOL material were found on the surface that were blasted out as a result of the laser shelling. Defects in hydrophilic and hydrophobic acrylic materials differ. Material particles can detach from the IOL and were found on the surface of the samples. The results of the laboratory study illustrate the importance of a precise and careful approach to Nd:YAG capsulotomy in order to avoid permanent damage to the IOL. The use of an appropriate contact glass and posterior offset setting to increase safety should be carried out routinely.

Glare prediction and mechanism of adaptation following implantation of hydrophilic and hydrophobic intraocular lenses.

Glare is a known side effect of intraocular lens (IOL) implantation, affected principally by IOL material and optics, although it is reported subjectively to decrease in impact with time. However, little objective data have been published on changes over time, how these relate to subjective reports, and whether those who will report greater glare symptoms can be predicted prior to IOL implantation. A total of 32 patients (aged 72.4 ± 8.0 years) with healthy eyes were implanted bilaterally with hydrophilic 600s (Rayner, Worthing, UK) or hydrophobic Acrysof (Alcon, Texas, USA) acrylic IOLs (n = 16 each, randomly assigned). Each patient reported their dysphotopsia symptoms subjectively using the validated forced choice photographic questionnaire for photic phenomena, and halo size resulting from a bright light in a dark environment was quantified objectively in eight orientations using the Aston Halometer. Assessment was performed binocularly pre-operatively and at 1, 2, 3, and 4 weeks after IOL implantation. The study was carried out at the National Health Service Ophthalmology Department, Queen Elizabeth Hospital, Birmingham, UK. Visual acuity (average 0.37 ± 0.26 logMAR) did not correlate with subjective glare (r = 0.184, p = 0.494) or objective glare (r = 0.294, p = 0.270) pre-surgery. Objective halo size (F = 112.781, p < 0.001) decreased with cataract removal and IOL implantation and continued to decreased over the month after surgery. Subjective dysphotopsia complaints (p < 0.001) were also greater pre-surgery, but did not change thereafter (p = 0.228). In neither case was there a difference with IOL material (p > 0.05). It was not possible to predict post-surgery dysphotopsia from symptoms or a ratio of symptoms to halo size pre-surgery (p > 0.05). Subjective dysphotopsia and objective halos caused by cataracts are greatly reduced by implantation of IOL after cataract removal causing few perceivable symptoms. However, objective measures are able to quantify a further reduction in light scatter over the first month post-IOL implantation, suggesting that any subjective effects over this period are due to the healing process and not due to neuroadaptation.

Sutured scleral fixation of existing subluxated/dislocated acrylic one-piece intraocular lenses.

To evaluate the visual and refractive outcomes in cases after sutured scleral fixation of existing subluxated or dislocated acrylic one-piece intraocular lenses (IOLs). This study retrospectively enrolled a consecutive series of patients who underwent a surgery of sutured existing subluxated or dislocated IOLs from October 2018 to June 2020. All patients underwent comprehensive preoperative and postoperative ophthalmologic examination, and data were collected including age, sex, surgical indications, best-corrected visual acuity, refractive error, intraocular pressure. Presence of intraoperative and postoperative surgical complications was documented. A total of 20 consecutive cases were enrolled for analysis with mean final follow-up period 9.8±5.3mo. Visual acuity improved from a mean of 0.35 (0.46±0.32 logMAR) preoperatively to 0.61 (0.21±0.18 logMAR) at the 3-month follow-up (P=0.002). The mean amount of preoperative keratometric astigmatism and total postoperative refractive astigmatism was -1.24±0.80 diopters (D) and -1.42±0.97 D, respectively. There was no statistically significant difference between preoperative and postoperative astigmatism (P=0.156). The mean IOL-induced astigmatism was -0.23±0.53 D. The mean spherical equivalent at the 3-month follow-up was -0.1±0.94 D. No major complications were noted during the follow-up period. Surgical techniques using sutured scleral fixation of existing subluxated or dislocated acrylic one-piece IOLs result in favorable visual and refractive outcomes without major complications.