Evolution in the Risk of Cataract Surgical Complications among Patients Exposed to Tamsulosin

The Selective α1 Antagonist Tamsulosin Alters ECM Distributions and Cellular Metabolic Functions of ARPE 19 Cells in a Concentration-Dependent Manner

The purpose of the present study was to examine the effect of the selective α1 antagonist tamsulosin (TAM) on human retinal pigment epithelium cells, ARPE 19. Two-dimension (2D) and three-dimension (3D) cultured ARPE 19 cells were used in the following characterizations: (1) ultrastructure by scanning electron microscopy (SEM) (2D); (2) barrier functions by transepithelial electrical resistance (TEER) measurements, and FITC-dextran permeability (2D); (3) real time cellular metabolisms by Seahorse Bioanalyzer (2D); (4) physical properties, size and stiffness measurements (3D); and (5) expression of extracellular matrix (ECM) proteins, including collagen1 (COL1), COL4, COL6 and fibronectin (FN) by qPCR and immunohistochemistry (2D and 3D). TAM induced significant effects including: (1) alteration of the localization of the ECM deposits; (2) increase and decrease of the TEER values and FITC-dextran permeability, respectively; (3) energy shift from glycolysis into mitochondrial oxidative phosphorylation (OXPHOS); (4) large and stiffened 3D spheroids; and (5) down-regulations of the mRNA expressions and immune labeling of most ECM proteins in a concentration-dependent manner. However, in some ECM proteins, COL1 and COL6, their immunolabeling intensities were increased at the lowest concentration (1 μM) of TAM. Such a discrepancy between the gene expressions and immunolabeling of ECM proteins may support alterations of ECM localizations as observed by SEM. The findings reported herein indicate that the selective α1 antagonist, TAM, significantly influenced ECM production and distribution as well as cellular metabolism levels in a concentration-dependent manner.

[Intraoperative floppy iris syndrom (IFIS) associated with tamsulosin]

BACKGROUND

Tamsulosin is one of the most commonly prescribed alpha-1A antagonists for the treatment of benign prostatic syndrome (BPS). Patients treated with tamsulosin often develop intraoperative floppy iris syndrome (IFIS) during cataract surgery. This leads to increasing miosis and an undulating iris, which increases the risk of complications significantly and can cause permanent damage.

AIM OF THE WORK

The aim is to raise awareness for the effects of tamsulosin intake before cataract surgery.

MATERIAL AND METHODS

We conducted a critical review of publications on the association of IFIS in cataract surgery with alpha-receptor blockers.

RESULTS AND DISCUSSION

Tamsulosin has a risk of complications of up to 80 %, whereas doxazosin and alfuzosin only have a 15-20 % chance of complications. Tamsulosin therefore represents a significant risk factor for permanent secondary damage after cataract surgery. Even after discontinuing tamsulosin, IFIS was still observed after up to 3 years. Nevertheless, pausing of tamsulosin intake is recommended. An alternative preparation should therefore be preferred in patients who have not yet had cataract surgery. If patients are already pseudophakic, tamsulosin can be given without concern.

Relationship Between Tamsulosin Use and Surgical Complications of Cataract Surgery in Elderly Patients: Population-Based Cohort Study

Purpose

Although several previous studies have investigated the relationship between tamsulosin use and surgical complications of cataract surgery, no population-based cohort study has been conducted for the Asian population. We aimed to investigate the relationship between tamsulosin use and surgical complications of cataract surgery in the Korean elderly population.

Methods

This nationwide population-based retrospective cohort study included elderly patients (≥60 years) who had undergone cataract surgery in the period from 2003 to 2015. Baseline characteristics were age, sex, income, residence, and systemic, and ocular comorbidities (glaucoma, myopia, eye trauma, diabetes mellitus with ophthalmic manifestations, severe cataract, age-related macular degeneration). The exposure of interest was tamsulosin use within 1 year before cataract surgery. Logistic regression model was used to evaluate the relationship of tamsulosin use with surgical complications of cataract surgery.

Results

The rate of surgical complications of cataract surgery was 0.88% (375/42,539) in the non-tamsulosin group and 0.83% (71/8,510) in the tamsulosin group. The groups showed no significant difference in the risk of surgical complications of cataract surgery in the unadjusted model [odds ratio (OR) = 0.946; 95% confidence interval (CI):0.733–1.220; P = 0.669]. Additionally, tamsulosin use was not significantly associated with surgical complications of cataract surgery in the fully adjusted model accounting for age, income, residence, and systemic and ocular comorbidities (OR = 0.997; 95% CI: 0.749–1.325; P = 0.981).

Conclusions

The rate or risk of surgical complications of cataract surgery does not change with tamsulosin use. We suggest that better surgical techniques and surgeons' cognizance of the patient's tamsulosin use could improve surgical outcomes, without increasing surgical complications.

Dealing with floppy iris syndrome

PURPOSE OF REVIEW

The aim of this study was to review and summarize recent findings and advancements regarding intraoperative floppy iris syndrome (IFIS). Although many improvements have been made for the management of IFIS, it remains a challenging condition for surgeons. An understanding of the syndrome as well as the multitude of tools to mitigate risk of complication is important for surgeons operating on high-risk patients.

RECENT FINDINGS

A variety of management approaches have been modified and improved or further supported with new data, such as intracameral compounds, intraoperative devices and surgical techniques.

SUMMARY

An understanding of risk factors is important for the identification of at-risk patients. A variety of approaches can greatly reduce incidence of IFIS complications. Multiple management strategies should be utilized to further reduce risk during these difficult surgeries.

Adiposity by Differing Measures and the Risk of Cataract in the UK Biobank: The Importance of Diabetes

Purpose

To examine the association between adiposity by differing measures and incident cataract and identify important factors contributing to the association.

Methods

Our analysis included 153,139 adults from the UK Biobank, aged 40 to 70 years at baseline (2006-2010). Cataract was ascertained using hospital inpatient, and self-reported data until the early of 2021. Anthropometric measures, body fat percentage, and glycosylated hemoglobin (HbA1c) were measured at baseline.

Results

During a median follow-up of 10.9 years, 15,255 cases of incident cataract were documented. HbA1c was an important contributor to the association between obesity and incident cataract. Obesity; defined by body mass index was associated with an increased risk of cataract (hazard ratio [HR], 1.21 95% confidence interval [CI], 1.16-1.26), and this association was attenuated but remained significant after additional adjustment for HbA1c (HR, 1.05; 95% CI, 1.00-1.10). Similar results were observed for obesity defined by waist circumference or waist-to-hip ratio. Obesity defined by fat percentage was associated with an increased risk of cataract before but not after adjustment for covariates. The association between obesity defined by body mass index and incident cataract was positively significant in individuals with normal HbA1c (HR, 1.07; 95% CI, 1.02-1.13), but inversely significant in those with prediabetes (HR, 0.80; 95% CI, 0.67-0.96) or diabetes (HR, 0.74; 95% CI, 0.61-0.89).

Conclusions

Anthropometric measurements are more predictive of cataract than bioelectrical impedance measures. Diabetes plays an important role in the association between obesity and incident cataract.

Heat treatment of soluble proteins isolated from human cataract lens leads to the formation of non-fibrillar amyloid-like protein aggregates

The loss of crystallins solubility with aging and the formation of amyloid-like aggregates is considered the hallmark characteristic of cataract pathology. The present study was carried out to assess the effect of temperature on the soluble lens protein and the formation of protein aggregates with typical amyloid characteristics. The soluble fraction of lens proteins was subjected for heat treatment in the range of 40-60 °C, and the nature of protein aggregates was assessed by using Congo red (CR), thioflavin T (ThT), and 8-anilinonaphthalene-1-sulfonic acid (ANS) binding assays, circular dichroism (CD), Fourier-transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM). The heat-treated protein samples displayed a substantial bathochromic shift (≈15 nm) in the CR's absorption maximum (λ_max) and increased ThT and ANS binding. The heat treatment of lens soluble proteins results in the formation of nontoxic, β-sheet rich, non-fibrillar, protein aggregates similar to the structures evident in the insoluble fraction of proteins isolated from the cataractous lens. The data obtained from the present study suggest that the exposure of soluble lens proteins to elevated temperature leads to the formation of non-fibrillar aggregates, establishing the role of amyloid in the heat-induced augmentation of cataracts pathology.

Intraoperative floppy iris syndrome: an updated review of literature

Intraoperative Floppy iris syndrome(IFIS) remains a challenge for surgeons during phacoemulsification. Initially, it was related to the use of tamsulosin, an alpha adrenergic receptor blocker used in benign prostatic hyperplasia. Subsequently, other alpha adrenergic receptor such as alfuzosin, terazosin and doxazosin alongwith different other class of medications and systemic risk factors were identified. Other class of medications includes 5-alpha reductase inhibitor, angiotensin receptor antagonist, benzodiazepines, antipsychotics and antidepressants. Other risk factors include increasing age, male gender, diabetes, hypertension and decreased preoperative pupil diameter. It is very important for surgeons to identify these risk factors preoperatively and take appropriate preoperative and intraoperative measures to tackle the dreaded complications of IFIS. Sometimes, it is important for an ophthalmologist to work in cooperation with physician and urologist to minimize the complications. In conclusion, awareness of the risk factors associated with IFIS, their detailed preoperative assessment and intraoperative measures and surgical intervention is crucial in addressing IFIS. Lack of awareness can turn a routine, uneventful surgery into one with significant visual morbidity.

Distribution and Predictors of Initial Glaucoma Care Among Ophthalmologists and Optometrists: A Population-based Study

PURPOSE

To evaluate evolution in the distribution of new glaucoma patients between ophthalmologists and optometrists, and to examine factors predicting provider type, in the context of expansion in the scope of optometry practice.

PATIENTS AND METHODS

A population-based study was undertaken using validated datasets in Ontario, Canada from 2007 to 2018, encompassing time before and after optometry practice scope expansion in 2011. All patients aged 66 and older receiving a glaucoma suspect diagnosis or first-line therapy for glaucoma from ophthalmologists or optometrists were enrolled. Predictors of provider type were evaluated using logistic regression.

RESULTS

From 2007 to 2018, 401,560 patients received initial glaucoma care, including 303,440 by ophthalmologists and 98,120 by optometrists. Population rates of glaucoma suspect diagnosis increased for both providers over the study period. The rate of therapy initiation increased annually among optometrists after 2011, while the rate remained stable over that period among ophthalmologists. By 2018, 88% of patients initiating therapy and 59% of patients first diagnosed as a glaucoma suspect received that care from ophthalmologists. In the final study year, therapy initiations per provider were lower among optometrists (median: 2/provider; interquartile range: 1 to 3) than among ophthalmologists (median: 26.5/provider, interquartile range: 10 to 53). Patients were more likely to receive care from an ophthalmologist than an optometrist if they were older, had higher ocular or systemic comorbidity, or lived in urban settings.

CONCLUSIONS

Optometrists have a large and growing role in diagnosing glaucoma suspects; however, despite scope expansion, optometrists play a much smaller role in initiating glaucoma therapy.

Trehalose Inhibits the Heat-Induced Formation of the Amyloid-Like Structure of Soluble Proteins Isolated from Human Cataract Lens

The age-dependent loss of solubility and aggregation of crystallins constitute the pathological hallmarks of cataract. Several biochemical and biophysical factors are responsible for the reduction of crystallins' solubility and formation of irreversible protein aggregates, which display amyloid-like characteristics. The present study reports the heat-induced aggregation of soluble proteins isolated from human cataract lenses and the formation of amyloid-like structures. Exposure of protein at 55 °C for 4 h resulted in extensive (≈ 60%) protein aggregation. The heat-induced protein aggregates displayed substantial (≈ 20 nm) redshift in the wavelength of maximum absorption (λ_max) of Congo red (CR) and increase in Thioflavin T (ThT) fluorescence emission intensity, indicating the presence of amyloid-like structures in the heat-induced protein aggregates. Subsequently, the addition of trehalose resulted in substantial inhibition of heat-induced aggregation and the formation of amyloid-like structure. The ability of trehalose to inhibit the heat-induced aggregation was found to be linearly dependent upon its concentration used. The optimum effect was observed in the presence of 30-40% (w/v) trehalose where the aggregated was found to be reduced from 60 to 30%. The present study demonstrated the ability to trehalose to inhibit the protein aggregation and interfere with the formation of amyloid-like structures.

Intraoperative Floppy Iris Syndrome: Updated Perspectives

Almost fifteen years since its initial description, intraoperative floppy iris syndrome (IFIS) during phacoemulsification surgery remains a challenge for cataract surgeons in all its key aspects that include the stratification of the preoperative risk, preoperative prophylaxis treatment, surgery design and intraoperative management. Since its original association with tamsulosin intake, IFIS has been positively correlated with a plethora of risk factors which include: gender, age, hypertension, other a1-adrenergic receptor antagonists, finasteride, angiotensin II receptor inhibitors, benzodiazepines, antipsychotics, hypertension drugs and decreased dilated pupil diameter. The assessment and stratification of the preoperative risk is pivotal in screening patients prone to develop IFIS. For these patients, it is essential that preoperative prophylaxis, employment of necessary measures and surgical technique modifications are considered. A multidisciplinary approach of IFIS is a mandate, thus ophthalmologists, urologists and sometimes other specialties should cooperate to “educate” each other about the risks of their respective fields. They both must be aware of the joint statement on IFIS by the American Academy of Ophthalmology and the American Society of Cataract and Refractive Surgery which suggests either the initiation of tamsulosin after phacoemulsification or the use of a non-selective a1-ARA for benign prostatic hyperplasia treatment. In conclusion, awareness of the risk factors associated with IFIS and their detailed preoperative documentation is crucial in addressing IFIS. The lack of such an awareness can turn a routine, uneventful surgery into one with significant visual morbidity.