Lens Instability Research Articles

Difficulties of Cataract Surgery in Lens-Induced Glaucoma Due to Subluxated Cataract

Introduction: Cataract is a disease of the eye in which the normal clear lens has opacified and obscured the passage of light. A mature cataract occurs when the lens is opacified. Lens subluxation is a condition when the crystalline lens is not in its anatomical position that can result in decreased anterior chamber depth. It is a potentially high risk of developing pupillary block, leading to lens-induced glaucoma (secondary angle closure glaucoma). In this case, the definitive therapy is lens extraction, which is challenging for cataract surgeons. This case report aims to expose the difficulties of cataract surgery in lens-induced glaucoma due to subluxated cataract. Case Presentation: A 56-year-old male presented with unable to see in his right eye, followed by foggy vision, glare when seeing the light, and a history of an acute glaucoma attack. His right best corrected visual acuity (BCVA) was 1/300, and the intraocular pressure (IOP) was 5 mmHg on therapy with glaucoma medications. Slit lamp examination of the right eye showed a shallow anterior chamber, irradiated iris, mid-dilated pupil, completely cloudy lens, and a capsular instability around 12 to 6 clock hours (180°/2 quadrant). This patient was diagnosed with mature cataract and lens-induced glaucoma due to subluxated mature cataract and was given glaucoma medications also underwent phacoemulsification (PE) along with Intraocular lens (IOL) and capsular tension ring implantation due to the lens instability and excessive lens movement. Conclusions: Cataract surgery for subluxated mature cataract and lens-induced glaucoma is challenging because of the shallow anterior chamber, capsular instability, and excessive lens movement. A thorough diagnosis, preoperative evaluation, postoperative monitoring, and evaluation are essential for safe cataract surgery, reducing the risk of complications and achieving a good result.

Результаты смешанной цилиокапсулярной фиксации трехчастной ИОЛ при факоэмульсификации у пациентов с несостоятельностью связочного аппарата хрусталика

Purpose. To evaluate clinical results of mixed ciliary-capsular fixation of a three-piece IOL in combination with the intracapsular ring's implantation during phacoemulsification in patients' zonular weakness caused by pseudoexfoliative (PEX) syndrome. Material and methods. This study included 78 patients (86 eyes) with complicated cataract and PEX syndrome associated with zonular weakness and natural lens instability. The average age of the patients was 74.3±9.3 years. Phacoemulsification was performed in a standard technique and followed by ciliary-capsular fixation of a three- piece IOL in all cases. Preoperative and postoperative follow up period lasted from 1st day until 10 months postop. It included biomicroscopy, visual acuity measurement, keratometry, tonometry, ultrasonic biomicroscopy, optical coherence tomography of the posterior segment of the eye. Results. At the 2nd day postop (86 cases) UCVA and BCVA were 0.46±0.29 and 0.58±0.27 respectively, IOP was 16.48±2.81 mm Hg; at 10 months postop (38 cases) UCVA and BCVA – 0.54±0.31 and 0.79±0.28, IOP – 15.34±3.71 mm Hg. The average deviation of the predicted refraction at the 2 days after surgery was –0.29±0.77 D with no significant change after 10 months. Efficiency ratio at 10 months postop was 193, the safety factor was 285. This type of IOL fixation didn't lead to an increase in IOP, development of chronic inflammation such as iridocyclitis or any other comorbidity. All IOLs were stable position regardless of the status of the zonular fibers. Conclusion. As a result of a preliminary study, it was found that mixed ciliary-capsular fixation of a three-piece IOL provides its stable position, high clinical and functional results in the early and late postoperative period after phacoemulsification in patients with pseudoexfoliative syndrome and failure of the lenticular ligamentous-capsular system. Key words: pseudoexfoliative syndrome, zonular weakness, intraocular lens, ciliary-capsular fixation, lens subluxation, myopic shift

Sulcus intraocular lens implantation in 17 dogs using a modified ab externo technique.

To describe a modified ab externo method of sulcus intraocular lens (IOL) fixation and report outcomes of eyes treated with this approach. Records of patients with lens instability or luxation that underwent a lensectomy and sulcus IOL implantation from January 2004 to December 2020 were reviewed. Nineteen eyes of 17 dogs had a sulcus IOL placed via a modified ab externo approach. The median follow-up time was 546 days (range 29-3387 days). Eight eyes (42.1%) developed POH. A total of six eyes (31.6%) developed glaucoma and required medical management long term to control IOP. The IOL position was satisfactory in most cases. Nine eyes developed superficial corneal ulcers within 4 weeks following surgery, all of which healed without complication. At the time of the last follow-up, 17 eyes were visual (89.5%). The technique described represents a potentially less technically challenging option for sulcus IOL implantation. The success rate and complications are similar to previously described approaches.

Comparative effects of latanoprost and latanoprostene bunod on intraocular pressure and pupil size in ophthalmologically normal Beagle dogs.

To compare effects of latanoprost, a topical prostaglandin analogue (PGA) commonly used to treat glaucoma and lens instability in dogs, and latanoprostene bunod, a novel PGA with a nitric oxide-donating moiety, on intraocular pressure (IOP) and pupil diameter (PD). Ten ophthalmologically normal Beagle dogs. Dogs were treated twice a day for 5days in a randomly selected eye with either latanoprost or latanoprostene bunod. After a 6-week washout period, dogs were treated with the opposite drug. IOP and PD were measured at treatment times, at midday on days 1 and 5, and for 6days post-treatment. Both drugs significantly decreased IOP and PD. At midday on day 5 of treatment, mean IOP in eyes treated with latanoprost was 4.5mmHg lower than the fellow eye and 3.0mmHg lower than the same eye at baseline, while mean IOP in eyes treated with latanoprostene bunod was 5.5mmHg lower than the fellow eye and 3.6mmHg lower than baseline. Mean PD was 0.94mm in eyes treated with latanoprost and 0.76mmHg in eyes treated with latanoprostene bunod. There was no significant difference between the two drugs for either parameter at that time point (p=.372 and .619, respectively, for IOP relative to control and to baseline; p=.076 for PD) or when analyzed longitudinally. Significant diurnal variation in PD was noted and may have implications for treatment of lens' instability. Latanoprost and latanoprostene bunod produce similar IOP reduction and miosis in normal canine eyes.

Comparison of intraocular pressures estimated by rebound and applanation tonometry in dogs with lens instability: 66 cases (2012-2018).

To compare intraocular pressures (IOPs) estimated by rebound and applanation tonometry for dogs with lens instability. 66 dogs. Medical records of dogs examined between September 2012 and July 2018 were reviewed for diagnoses of anterior (ALL) or posterior (PLL) lens luxation or lens subluxation. Estimates of IOP obtained with rebound and applanation tonometry significantly differed from each other for all types of lens instability considered collectively (mean ± SE difference between tonometric readings, 8.1 ± 1.3 mm Hg) and specific types of lens instability considered individually (mean ± SE difference between tonometric readings: ALL, 12.8 ± 2.5 mm Hg; PLL, 5.9 ± 1.7 mm Hg; subluxation, 2.8 ± 0.8 mm Hg). Median (range) differences between rebound and applanation tonometer readings for dogs with ALL was 5 mm Hg (-9 to 76 mm Hg), with PLL was 3 mm Hg (-1 to 19 mm Hg), and with lens subluxation was 3 mm Hg (-9 to 18 mm Hg). In eyes with ALL, rebound tonometer readings exceeded applanation tonometer readings on 44 of 60 (73%) occasions. Rebound tonometry yielded higher estimates of IOP than did applanation tonometry in eyes with ALL and with all types of lens luxation considered collectively. Estimates of IOP in eyes with lens instability should ideally be obtained with both rebound and applanation tonometers. Veterinarians with only one type of tonometer should interpret results for dogs with lens instability concurrent with physical examination findings.

Гидродинамическая коррекция выполнения факоэмульсификации при нестабильности связочного аппарата хрусталика

Гидродинамическая коррекция выполнения факоэмульсификации при нестабильности связочного аппарата хрусталика

Characteristics of Patients with Pseudoexfoliation Syndrome at a Tertiary Eye Care Center in Jordan: A Retrospective Chart Review.

PurposeTo present the clinical profile of patients with pseudoexfoliation (PXF) and describe its association with pseudoexfoliation glaucoma and cataract surgery complications at a university hospital in Jordan.MethodsElectronic chart search was performed among patients aged ≥ 50 years who attended the Jordan University Hospital between January 2015 and March 2018, to identify patients with pseudoexfoliation. Data derived from history and ophthalmic examination regarding laterality of pseudoexfoliation, presence of glaucoma, glaucoma surgery, cataract, cataract surgery, lens instability, and complications of cataract surgery were collected and analyzed.ResultsOf 19,753 patient records searched, 962 (477 male and 485 female) had PXF (4.9%). The mean (SD) age was 71.8 (8.1) years. Pseudoexfoliation was unilateral in 539 patients (56.0%). The mean age of patients with clinically bilateral PXF was significantly higher than those with clinically unilateral PXF (p = 0.001). Pseudoexfoliation glaucoma was present in 237 of 962 (25.4%) patients with PXF and was significantly associated with clinically bilateral PXF (p < 0.001) and male gender (p = 0.001). In 454 (48.9%) patients (638 eyes) who underwent cataract surgery, there was no statistically significant difference in the rate of intraoperative complications between PXF eyes and the fellow eyes of clinically unilateral PXF eyes (p = 0.37), or between patients with clinically unilateral and clinically bilateral PXF (p = 0.78).ConclusionIn this large hospital-based study, the frequency of PXF was 4.9%. Glaucoma was present in one fourth of patients and was significantly associated with clinically bilateral PXF and male gender. Cataract surgery complication rates were not statistically different between PXF and the fellow eyes of clinically unilateral PXF eyes. Surgeons need to be aware of the potential increased risk of intraoperative complications in both groups.

Fenestrated Scleral Lenses: Back to the Origins? Review of Their Benefits and Fitting Techniques.

This review illustrates the history of fenestrated scleral lenses, reporting personal communication from one of the present authors; describes their peculiarities and disadvantages; explains the fitting methods so far used; and recommends future fitting methods.Indications and benefits of scleral lenses are widely described in the literature. The introduction of more advanced gas-permeable materials allowed scleral lenses to spread and be available to patients worldwide. Despite the improvement of the gas-permeable scleral lens' clinical performance, complications associated with corneal hypoxia persist, especially in patients with corneal endothelial abnormalities. Fenestrated scleral lenses may solve different complications caused by hypoxia. Also, fenestrated scleral lenses may be beneficial for several issues such as handling difficulties, midday fogging, lens suction, lens instability, conjunctival compression, and alteration of IOP. There is a need and a benefit to directly comparing fenestrated scleral lenses to sealed gas-permeable scleral lenses. This topical review allows practitioners to understand the fenestration philosophy in scleral lenses, practice better, and obtain information on their indications and fitting process. Industry and patients will benefit from future advances in scleral lens designs.

Open-angle glaucoma in the Petit Basset Griffon Vendeen.

To report the prevalence and clinical characteristics of an open-angle glaucoma in Petit Basset Griffon Vendeen (PBGV) dogs in the United Kingdom (UK). At breed society clinics extending over a 6-year period, 366 dogs of varying ages and both sexes were clinically examined for signs of glaucoma using slit-lamp biomicroscopy, indirect and direct ophthalmoscopy, tonometry, and gonioscopy. The prevalence of glaucoma was 10.4% (38 dogs). Clinical signs of the disease presented from 3 years of age onwards, the commonest initial feature being the elevation of intraocular pressure (IOP) in 15 dogs (39.4%). In addition to elevated IOP, another 13 dogs (34.2%) presented with other features of glaucoma, some with lens subluxation and globe enlargement and all with possible or known vision defects. In the remaining 10 dogs (26.3%), phacodonesis or lens subluxation was observed before subsequent elevation of IOP. High prevalence and similarity to the primary open-angle glaucoma (POAG) seen in the Beagle and Elkhound breeds indicate that an open-angle glaucoma is present in the PBGV in the UK and that this disease may be genetically determined in this breed. Although increased IOP is the commonest early diagnostic feature, lens instability prior to an increase in IOP may be part of the clinical picture.

Post-Marketing Survey of Adverse Events Following Ocriplasmin.

To study the post-marketing safety profile of ocriplasmin (Jetrea; ThromboGenics, Iselin, NJ) as experienced by retinal physicians in the United States. Two thousand four hundred sixty-five retinal physicians were surveyed regarding their frequency of use of ocriplasmin and reports of ocular adverse events. There were 270 respondents (11%) who reported treating 1,056 eyes with ocriplasmin. The reports of adverse events (AE) were as follows: acute decline in visual acuity (16.95%), development of submacular fluid or serous retinal detachment (10.23%), dyschromatopsia (9.09%), progression of vitreomacular traction to macular hole (8.71%), development of retinal detachment (2.65%), development of retinal tear (1.99%), development of afferent pupillary defect (1.80%), electroretinography abnormalities (0.57%), crystalline lens instability (0.38%), and vasculitis (0.28%). Although the frequency of some ocular AEs reported in this study are comparable to those reported in the phase 3 registration trials, additional phase 4 safety studies are warranted to better understand the pathophysiology and clinical relevance of ocular AEs of ocriplasmin.

Zoom lens calibration with zoom- and focus-related intrinsic parameters applied to bundle adjustment

A zoom lens is more flexible for photogrammetric measurements under diverse environments than a fixed lens. However, challenges in calibration of zoom-lens cameras preclude the wide use of zoom lenses in the field of close-range photogrammetry. Thus, a novel zoom lens calibration method is proposed in this study. In this method, instead of conducting modeling after monofocal calibrations, we summarize the empirical zoom/focus models of intrinsic parameters first and then incorporate these parameters into traditional collinearity equations to construct the fundamental mathematical model, i.e., collinearity equations with zoom- and focus-related intrinsic parameters. Similar to monofocal calibration, images taken at several combinations of zoom and focus settings are processed in a single self-calibration bundle adjustment. In the self-calibration bundle adjustment, three types of unknowns, namely, exterior orientation parameters, unknown space point coordinates, and model coefficients of the intrinsic parameters, are solved simultaneously. Experiments on three different digital cameras with zoom lenses support the feasibility of the proposed method, and their relative accuracies range from 1:4000 to 1:15,100. Furthermore, the nominal focal length written in the exchangeable image file header is found to lack reliability in experiments. Thereafter, the joint influence of zoom lens instability and zoom recording errors is further analyzed quantitatively. The analysis result is consistent with the experimental result and explains the reason why zoom lens calibration can never have the same accuracy as monofocal self-calibration.

Trans‐corneal reduction of anterior lens luxation in dogs with lens instability: a retrospective study of 19 dogs (2010–2013)

To evaluate the success rate and outcome of trans-corneal reduction of anterior lens luxation (TR-ALL) in dogs with lens instability. Nineteen dogs with anterior lens luxation. Medical records of dogs with anterior lens luxation (ALL) were reviewed: dogs were included if TR-ALL was performed followed by medical therapy in the form of topical 0.005% latanoprost ophthalmic solution. The duration of ALL, vision status, ophthalmic examination abnormalities, reason for performing TR-ALL and details of TR-ALL were recorded. Success rate for TR-ALL as well as postprocedure complications were also assessed. Twenty eyes from 19 dogs met the inclusion criteria. Median age was 6.5 years (0.3-15 years) and 47% were terriers (9/19). Successful TR-ALL was achieved in 85% of eyes (17/20); failure was attributed to posterior synechia or vitreous expansion. Short-term complications included corneal ulceration (2/20) and anterior uveitis (3/20); recurrence of anterior luxation occurred in only one dog. Median follow-up for visual eyes (11) following successful TR-ALL was 353 days (range of 1 to 1182 days). Vision was retained in 54.5% (6/11) of eyes with a median time to vision loss of 12 months as a result of glaucoma or presumed retinal detachment. Trans-corneal reduction of ALL provides a non-surgical alternative to intracapsular lens extraction (visual eyes) or enucleation (nonvisual eyes) in dogs. Long-term visual outcome of TR-ALL is comparable to intracapsular lens extraction for ALL.

Histopathologic evaluation of the anterior segment of eyes enucleated due to glaucoma secondary to primary lens displacement in 13 canine globes

PURPOSE To describe histologic anterior segment changes in eyes affected with primary lens displacement (PLD) and secondary glaucoma. METHODS Histologic sections stained with H&E from canine eyes enucleated because of PLD and secondary glaucoma were examined. RESULTS Thirteen eyes from 12 patients were evaluated. Four dogs were castrated males and eight spayed females. Median age was 8 years of age (range 3-13). Breeds included seven terriers and five other breeds. All eyes examined demonstrated varying degrees of inflammation involving the iris and cleft. Mononuclear and melanophagic infiltration of the cleft was found in all specimens. Four globes also showed polymorphonuclear infiltrate. Pre-iridal fibrovascular membranes were clearly identified in 10 of 13 eyes. Total inflammatory score was significantly greater in all globes examined compared with an age-matched group of normal dogs. The posterior pigmented iris epithelium demonstrated a consistent pattern of hyperplasia and/or hypertrophy and cystic degeneration, more prominent in the more central regions. In some cases, hyperplasia was of greatest severity in the mid-iris and associated with thinning or flattening of the pupillary region. CONCLUSIONS These results suggest that lens instability may be associated with chronic inflammation and secondary glaucoma. Mechanical irritation from an unstable lens may result in hypertrophy and/or hyperplasia of the posterior pigmented iris epithelium and subsequent cellular exfoliation and release of melanin. An inflammatory reaction directly or indirectly related to melanin release may obstruct the outflow pathways ultimately leading to glaucoma and loss of vision. Use of topical steroids may be warranted in dogs with PLD.

Optical low-coherence reflectometry enables preoperative detection of zonular weakness in pseudoexfoliation syndrome

To evaluate optical ocular components in patients with pseudoexfoliation syndrome using optical low-coherence reflectometry. A prospective cohort study of 224 eyes of patients planned for cataract surgery was conducted in the period from January 2009 until July 2009. Patients were divided in two groups: the first group of 47 eyes with cataract complicated with pseudoexfoliation syndrome and the control group of 177 eyes with uncomplicated cataract. Each group was further divided into two subgroups based on its refractive state: emmetropes and hypermetropes. The optical low-coherence reflectometry biometer LENSTAR LS 900 was used to define ocular optical components. A statistically significant difference of ocular optical components was established between the two groups of patients and its matching subgroups: AL (t = 2.25; p < 0.05) and ACD (t = 2.24; p < 0.05) were significantly higher in the control group, PD was significantly higher in the control group hypermetropes than the PEX group hypermetropes (t = 2.21; p < 0.05) while LT (t = 3.01; p < 0.001), AST (t = 2.13; p < 0.05) and IOL (t = 3.06; p < 0.001) were higher in the PEX group of patients than in the control group. The optical low-coherence reflectometry enabled preoperative detection of zonular weakness and subsequent lens instability documented as a significantly shallower anterior chamber, thicker lens, and smaller pupillary diameter in the pseudoexfoliation syndrome group in the studied population.

Primary lens instability in ten related cats: clinical and genetic considerations

To describe bilateral lens instability in 10 related domestic shorthair cats over three generations. Complete ophthalmic examinations were performed. Lentectomies were carried out. Sections of affected lenses focused on the equatorial area were examined by transmission electron microscopy. The potential involvement of several candidate genes (ADAMTS17, ADAMTSL4, ADAMTS10 and FBN1) known to be associated with lens luxation in other species was investigated. The group of animals included 10 related cats, nine of them being affected by lens instability over three generations. Transmission electron microscopy showed the presence of zonular material at the lens equator. Signs of lens instability were not associated with other ocular disease. Analysis of the pedigree suggests a dominantly inherited condition. A mutation in ADAMTS17 was excluded, but a possible association between the condition and a microsatellite flanking FBN1 indicates this gene should be considered a strong candidate responsible for primary lens luxation in this pedigree. These observations suggest an inherent zonular defect unrelated to extraneous factors. The family relationship is compatible with a possible genetic basis, and the pedigree suggests that the condition could be dominant. Data also suggest the mutation in the FBN1 gene could be responsible for primary lens luxation in this pedigree of cats.

Saccadic lens instability increases with accommodative stimulus in presbyopes.

An SRI dual Purkinje image (dPi) eye tracker was used to measure lens wobble following saccades with increasing accommodative effort as an indirect measure of ciliary muscle function in presbyopes. Ten presbyopic subjects executed 32 four-degree saccades at 1-s intervals between targets arranged in a cross on illuminated cards at each of 9 viewing distances ranging from 0.5- to 8-D accommodative demands. Post-saccadic lens wobble artifacts were extracted by subtraction of P1 (H(1)/V(1)) position signals from P4 signals (Theta(H)/Theta(V)), both of which were sampled by the eye tracker at 100 Hz. A ray tracing eye model was also employed to model the fourth Purkinje image shifts for a range of lens translations and tilts. Combining all saccades from all subjects showed a significant positive relationship between lens wobble artifact amplitude and accommodative demand. Eye model simulations indicated that artifacts of the amplitude measured could arise from either lens tilts (in the range of 2-4 degrees) or lens translations (in the range of 0.1 to 0.2 mm). Saccadic lens wobble artifacts increase with accommodative effort in presbyopes, indicating preserved ciliary muscle function and greater relaxation of zonular tension with accommodative effort. Variation across subjects may reflect differences in accommodative effort, ciliary muscle function for a given effort, and/or in intraocular anatomy.

Medical Management of Primary Lens Instability in Dogs

Medical Management of Primary Lens Instability in Dogs

A modifiedab externoapproach for suture fixation of an intraocular lens implant in the dog

The goals of canine cataract and lens instability surgery should be to ensure a small incision, minimal tissue trauma, shortened surgical time, maintenance of the anterior chamber, and restoration of emmetropia through the use of a stable intraocular lens specifically designed for the canine eye. While this is usually the case with routine phacoemulsification and in-the-bag intraocular lens implantation, it is often not the case with lens instability, lens luxation or large posterior capsular ruptures. In such cases the incisions are often larger, surgical time and tissue trauma are excessive, and the patient is often left aphakic. The goal of this paper is to present a modified ab externo technique designed to allow removal of the lens and placement of a ciliary sulcus sutured IOL through a small incision, with minimal trauma and shortened surgical time. Use of this technique may allow more canine patients to be emmetropic postoperatively. In addition, the ease of this procedure may encourage earlier removal of an unstable lens and decrease the risk of secondary glaucoma and retinal detachment that occur in association with lens luxation.

Outcomes of nonsurgical management and efficacy of demecarium bromide treatment for primary lens instability in dogs: 34 cases (1990–2004)

To determine outcome of initial conservative management for primary lens luxation and evaluate topically administered demecarium bromide miotic treatment for prevention of anterior lens luxation, glaucoma, and vision loss in dogs. Retrospective case series. 34 dogs with primary lens luxation. Medical records of affected dogs were reviewed for times to anterior luxation, luxation of the lens in the opposite eye, development of glaucoma, and vision loss. At 4 to 6 weeks and at 3 months after diagnosis of lens instability (subluxation or posterior luxation), 100% (34/34 and 29/29, respectively) of conservatively managed eyes retained vision. At 1 year after diagnosis of lens instability, 80% (16/20) of conservatively managed eyes retained vision, and at 2 years after diagnosis of lens instability, 11 of 19 conservatively treated eyes retained vision. The only significant effect of miotic treatment was to delay anterior lens luxation in eyes with lens instability. Miotic treatment did not significantly affect the time from anterior lens luxation in 1 eye to anterior luxation in the other eye, time to onset of glaucoma, or time to loss of vision in eyes with an unstable lens. Prophylactic topically administered miotic treatment may be effective at delaying anterior luxation of an unstable lens in eyes affected by primary lens instability. Conservative medical management of dogs with primary lens instability is a reasonable alternative to surgical removal of a subluxated or posteriorly luxated lens via intracapsular lens extraction.

Postmortem microscopic evaluation and clinical correlation of a pseudophakic eye with pseudoexfoliation and loss of zonular support

We describe a pseudophakic patient with pseudoexfoliation who developed late intraocular lens (IOL) instability manifested by pseudophakodonesis, a change in refraction, and loss of glaucoma control. The patient subsequently required glaucoma surgery that was complicated by vitreous loss. Preoperative ultrasound biomicroscopy (UBM) failed to provide useful information regarding the zonular status. The patient died as a result of a malignancy, and the eye was donated for research. Anatomical evaluation confirmed the clinical impression of IOL placement in the bag and zonular laxity. Postmortem UBM helped explain some of the technical difficulties in examining zonules in the pseudophakic state.