Microinvasive glaucoma surgery: a review and classification of implant-dependent procedures and techniques.

The aim of this article is to discuss how physiology and anatomical background affect the effectiveness of implant-dependent microinvasive glaucoma surgery (MIGS). First, we provide a micro view of aqueous outflow and tissue behaviour. Second, we review studies exploring the mechanisms of the pressure-lowering effect of MIGS, as well as tissue behaviour during aqueous flow and tissue motion. We also describe and classify microinvasive surgical procedures and the most important types of implants, as well as their mechanisms of action, implantation techniques and efficacy. Further, we summarize the indications and surgical results presented in recent studies, providing an evidence-based update on novel and emerging MIGS techniques for the treatment of open-angle glaucoma. These data can help surgeons to personalize the management of glaucoma and to choose the best MIGS option for individual glaucoma patients.

Schlemm's canal: the outflow 'vessel'.

In a healthy eye, the aqueous humour (AH) flows via the ciliary body and trabecular meshwork into the collector channels, which carry it to the episcleral veins. In glaucoma, a heterogeneous group of eye disorders affecting approximately 60 million individuals worldwide, the juxtacanalicular meshwork offers greater resistance to the outflow of the AH, leading to an increase in outflow resistance that gradually results in elevated intraocular pressure (IOP). The present review comprehensively covers the morphology of Schlemm's canal (SC) and AH pathways. The path of the AH from the anterior chamber through the trabeculum into suprascleral and conjunctival veins via collector channels is described, and the role of SC in the development of glaucoma and outflow resistance is discussed. Finally, channelography is presented as a precise method of assessing the conventional drainage pathway and facilitating localization of an uncollapsed collector and aqueous veins. Attention is also given to the relationship between aqueous and episcleral veins and heartbeat. Possible directions of future research are proposed.

XEN Glaucoma Implant for the Management of Glaucoma in Naïve Patients versus Patients with Previous Glaucoma Surgery.

This retrospective study analyzed the surgical and refractive outcomes of a XEN Gel Implant (Allergan, Abbvie Company, Irvine, CA, USA) in naïve patients versus those with previous glaucoma surgery. We evaluated the efficacy of XEN implantation in 86 glaucoma patients during a long-term follow-up period. Patients were divided into two groups: naïve patients (Group 1) and patients with previous glaucoma surgery (Group 2). Eyes that received a XEN Gel Stent placement from December 2014 to October 2019 were included. Intraocular pressure (IOP) change, corrected distance visual acuity (CDVA), change in glaucoma medications, frequency of slit lamp revision procedures, and frequency of secondary glaucoma surgeries were the primary outcomes. In Group 1, the mean IOP before surgery was decreased significantly from 25.00 ± 7.52 mmHg to 16.83 ± 5.12 mmHg by the end of the study. In Group 2, the mean IOP decreased significantly from 25.35 ± 7.81 mmHg to 17.54 ± 5.34 mmHg. The mean IOP decrease from baseline was 29% in Group 1 and 27% in Group 2 (p = 0.567). There were no significant differences between the groups in the IOP baseline level, the final level, or the change between preoperative and final levels. The qualified success rate for Group 2 was 68.7% versus 76.5% for Group 1 for the initial procedure and 15.4% vs. 20.2%, respectively, for complete success rate (p > 0.05). However, at the end of the follow-up, more patients achieved an IOP < 18 mmHg in Group 1 than in Group 2. Despite the need for more anti-glaucoma medications, repeat XEN Gel implantation appears to show promising results in patients with previously failed anti-glaucoma procedures, owing to its minimal invasiveness.

Quantitative Assessment of Choroidal Parameters in Patients with Various Types of Diabetic Macular Oedema: A Single-Centre Cross-Sectional Analysis.

Diabetic macular oedema (DME) is an outcome of multiple, complex and not fully understood mechanisms. The aim of this study was to define the role of choroidopathy in the pathogenesis of various DME types. The retrospective cross-sectional single-centre study included 140 eyes from 105 patients with DME and 76 eyes from 52 non-diabetic controls. The eyes were stratified according to the type of DME: cystoid, diffuse, and with subretinal fluid. Optical coherence tomography-based choroidal parameters: thickness, volume, choroidal vascularity index (CVI), luminal area (LA), stromal area (SA), and total choroidal area (TCA) were compared. Eyes with DME, regardless of the type thereof, had lower choroidal thickness, volume, and CVI values than the controls. Further, the eyes with some specific DME types differed significantly from the controls in terms of LA and SA. While the eyes with various DME types did not differ significantly in terms of their choroidal thickness, volume and CVI, some between-group differences were found in LA, SA and TCA. Diabetic choroidopathy seems to play a role in the development of DME but is less likely involved in the pathogenesis of specific types thereof.

Impact of Three Waves of the COVID-19 Pandemic on the Rate of Elective Cataract Surgeries at a Tertiary Referral Center: A Polish Perspective.

The aim of this study was to assess the effect of three waves of the COVID-19 pandemic on the number of elective cataract surgeries. A retrospective single-center consecutive case series study was performed. We included all 12,464 patients who received cataract surgery in the period between 1 January 2016 and 31 May 2021. Monthly numbers of cataract surgeries during the pandemic were compared with monthly numbers in the reference years 2016-2019. In the pandemic the number of cataract surgeries decreased by 53.4%. The monthly numbers during the first, second and third wave of the pandemic were 77.5%, 51.5% and 29.7% lower, respectively, compared with the reference level. No rebound effect was observed once the pandemic restrictions were eased. Simultaneous bilateral cataract surgeries (SBCS) constituted 6.5% of cataract procedures performed in April and May 2021 compared with 0.77% carried out between May 2019 and March 2021. While the pandemic-affected monthly numbers of cataract surgeries tend to increase recently, they are still below the prepandemic level. Patients should be encouraged to weigh the risks of COVID-19-related morbidity and mortality against the benefits of cataract surgery. Reorganization of the logistics of cataract services is advisable with consideration of SBCS as one of the options.

The Impact of Three Waves of the COVID-19 Pandemic on the Characteristics of Primary Rhegmatogenous Retinal Detachments at a Tertiary Referral Centre.

PURPOSE: This study assessed the effect of three waves of the COVID-19 pandemic primarily on the number and timing of referrals due to rhegmatogenous retinal detachment (RRD) and secondarily on the demographic or clinical characteristics of patients. PATIENTS AND METHODS: A retrospective single-centre analysis of medical records included 247 eyes from 247 patients who underwent primary RRD repair with (phaco) vitrectomy between January 1, 2019, and May 31, 2021. RESULTS: The percentage of referrals due to primary RRD during the first year of pandemic (March 2020-February 2021) was 16.5% (p=0.179) lower than a year earlier. The percentage of referrals during the first, second and third wave of the pandemic was 48.4%, 18.5% and 26.1% (p=0.029, 0.475, 0.343) lower than in the corresponding months of 2019. A rebound effect was observed only after the first wave. The numbers of referrals in April and May 2021 were similar as in the corresponding months of 2019. No significant differences were observed in the demographic and clinical characteristics of patients admitted before and during the COVID-19 pandemic, other than a tendency towards a higher representation of women, younger persons, longer duration of symptoms but better visual acuity in the latter group. Silicone oil tamponade was used more frequently during the pandemic than before. CONCLUSION: In this study, the COVID-19 pandemic affected the number and timing of referrals due to RRD and the clinical but not demographic characteristics of the patients. The effect lessened with the duration of the pandemic. Previously raised concerns regarding the delay in RRD referrals may no longer be valid during a potential fourth wave of the pandemic. The impact of the pandemic's waves should be analysed separately, as such an approach provides a better insight into the fluctuations in the number of referrals due to RRD than a year-to-year comparison.

XEN Glaucoma Implant for the Management of Operated Uncontrolled Glaucoma: Results and Complications during a Long-Term Follow-Up.

This study aimed to analyze the surgical and refractive outcomes of XEN glaucoma implant (Allergan, an Abbvie company, Irvine, CA, USA), a minimally invasive surgical device for the treatment of operated uncontrolled glaucoma. Eyes that received XEN Gel Stent placement from December 2014 to October 2019 were retrospectively investigated. Intraocular pressure (IOP) change, best-corrected visual acuity (BCVA), change in glaucoma medications, frequency of slit lamp revision procedures, and frequency of secondary glaucoma surgeries were the primary outcomes. Seventy-two eyes of 72 subjects were included in the study: 32 (44%) men and 40 (56%) women. The follow-up period ranged from 1 to 50 months (median, 26.13 months). The mean IOP before surgery was 24.82 ± 8.03 mmHg and decreased to 17.45 ± 5.84 mmHg at the end of the study (mean difference [MD] = -7.48, 95% confidence interval [CI]: -10.04, -4.93; p < 0.001). The mean decrease from baseline was 23%. BCVA before surgery was 0.38 ± 0.30, and that at the end of the follow-up period improved to 0.47 ± 0.37, MD = 0.09, 95% CI: 0.04, 0.13; p < 0.001. Additional procedures (fluorouracil injection and bleb needling) were performed in 11/72 patients (15%). Further glaucoma surgery was necessary for 23.9% of the patients. XEN Gel Stent implantation is both safe and reasonably effective for lowering IOP in operated uncontrolled glaucoma patients.

Foveal Avascular Zone Does Not Correspond to Choroidal Characteristics in Patients with Diabetic Retinopathy: A Single-Center Cross-Sectional Analysis.

PURPOSE: The aim of the study was to compare two non-overlapping blood supply systems of the retina to obtain a better insight into the relation between diabetic macular retinopathy and choroidopathy. Specifically, the study focused on the relationships between (1) retinal vascular changes around the fovea in fluorescein angiography (FA) and (2) choroidal thickness, volume and other parameters assessed by optical coherence tomography (OCT). PATIENTS AND METHODS: The retrospective cross-sectional single-center study included 210 eyes from 152 patients with diabetic retinopathy (mean age 60.7±12.4 years, 49.3% of women; foveal avascular zone [FAZ] outline: 44.3% grade ≤2, 55.7% grade ≥3). The outline of FAZ, a measure of capillary loss due to ischemic processes, was analyzed on FA according to the Early Treatment Diabetic Retinopathy Study Research Group (ETDRS) standards. The eyes were stratified according to the FAZ outline and size and the presence of clinically significant diabetic macular edema (CSME). Then, resultant groups were compared in terms of the spectral domain OCT parameters: choroidal thickness and volume (within ETDRS subfields), luminal, stromal and total choroidal areas and choroidal vascularity index (based on the foveal scan). Statistical analysis was based on univariate models with the choroidal parameters as independent variables, and age, sex, panretinal photocoagulation, the severity of diabetic retinopathy and CSME as covariates. RESULTS: No significant relationships were found between the FAZ outline and area and choroidal characteristics of patients with diabetic retinopathy. In patients without CSME, no correlation was observed between the FAZ area and choroidal characteristics. In patients with CSME, no correlation was found between the FAZ area and choroidal characteristics other than the choroidal vascularity index. CONCLUSION: In patients with diabetic retinopathy, damage to the macular retinal vasculature (FAZ) does not seem to be associated with changes in the choroidal vasculature, and these two processes appear to occur independently.

Metabolomics Reveals Differences in Aqueous Humor Composition in Patients With and Without Pseudoexfoliation Syndrome.

Pseudoexfoliation syndrome (XFS) is stress- or inflammation-induced elastosis accompanied by excessive production of microfibrils and their deposition in the anterior segment of the eye. Approximately 60-70 million people are affected by XFS worldwide. It is a component of a systemic disorder, considered a major risk factor for accelerated cataract formation, cataract surgery complications and development of glaucoma, which untreated or inadequately treated may lead to blindness. Moreover, XFS has been associated with cardiovascular and cerebrovascular morbidity, dementia, sensorineural hearing loss and pelvic organ prolapse. The pathogenesis of XFS has not been fully elucidated yet. Aqueous humor (AH) is a transparent fluid filling the anterior and posterior chambers of the eye. Determination of AH metabolites that are characteristic for XFS may provide valuable information about the molecular background of this ocular disorder. The aim of this study was to compare the composition of AH in XFS and non-XFS patients undergoing cataract surgery. The AH samples from 34 patients (15 with XFS and 19 without) were analyzed using liquid chromatography coupled to a Quadrupole Time-of-Flight mass spectrometer (LC-QTOF-MS). The obtained metabolic fingerprints were analyzed using multivariate statistics. Eleven statistically significant metabolites were identified. Compared with the non-XFS group, the AH of patients with XFS contained significantly lower levels of amino acids and their derivatives, for example, arginine (-31%, VIP = 2.38) and homo-arginine (-19%, VIP = 1.38). Also, a decrease in the levels of two acylcarnitines, hydroxybutyrylcarnitine (-29%, VIP = 1.24) and decatrienoylcarnitine (-46%, VIP = 1.89), was observed. However, the level of indoleacetaldehyde in XFS patients was significantly higher (+96%, VIP = 2.64). Other significant metabolites were two well-recognized antioxidants, ascorbic acid (-33%, VIP = 2.11) and hydroxyanthranilic acid (-33%, VIP = 2.25), as well as S-adenosylmethionine, a compound with anti-inflammatory properties (-29%, VIP = 1.93). Metabolic pathway analysis demonstrated that the identified metabolites belonged to eight metabolic pathways, with cysteine and methionine metabolism as well as arginine and proline metabolism being the most frequently represented. XFS can be associated with enhanced oxidative stress and inflammation, as well as with the disturbances of cellular respiration and mitochondrial energy production. Implementation of non-targeted metabolomics provided a better insight into the still not fully understood pathogenesis of XFS.

Comparison of auditory sensations in patients who underwent cataract phacoemulsification surgery in the first and second eye.

To compare subjective auditory sensations of patients during the first and second eye cataract surgeries. Consecutive patients who underwent phacoemulsification of the first eye (group I) and second eye (group II) completed questionnaires designed to evaluate their auditory sensations in the operating room including background music, sound of working equipment, staff conversations, and surgeon's voice. This study included 124 patients in group I and 76 patients in group II. Patients most often heard nursing staff's conversations (91.9% and 96%, respectively, p > 0.05), surgeon's voice (87.9% and 86.8%, respectively, p > 0.05), and music (70.9% and 75%, respectively, p > 0.05). Music was the most pleasant experience (78.2% and 78.9%, respectively, p > 0.05). The sound of the working phacoemulsifier was the most undesirable sound (20.2% and 15.8%, respectively, p > 0.05). Patients in group II more often indicated that none of the sounds required elimination (69.7% and 52.6%, respectively, p = 0.013) or that staff conversations should be eliminated (13.2% and 3.1%, respectively, p = 0.005). The most desirable sounds during phacoemulsification include music and the surgeon's voice regarding the procedure. The most unpleasant sound was that that of phacoemulsifier. The commonest sounds to be eliminated in groups I and II included those of equipment and staff conversations.