The Effects of Glaucoma and Glaucoma Therapies on Corneal Endothelial Cell Density

Corneal endothelial cell density and associated factors among adults at a regional referral hospital in Uganda: a cross-sectional study

BACKGROUND

To assess the prevalence of low corneal endothelial cell density and correlates of corneal endothelial cell density among adults attending Mbarara University and Referral Hospital Eye Centre in Uganda.

METHODS

In this hospital-based cross-sectional study, participants 18 years and older, were enrolled. We obtained informed consent, and basic demographic data. We also conducted visual acuity, a detailed slit lamp examination, intra-ocular pressure, corneal diameter, tear-film break-up time, keratometry, A-scan, and pachymetry on all participants. A confocal microscope Heidelberg HRT3 was used to examine the central cornea and to obtain the mean cell density (cells/mm2). To calculate the proportion of low endothelial cell density, descriptive statistics were used, whereas correlates of endothelial cell density were assessed, using linear regression analyses.

RESULTS

We evaluated a total of 798 eyes of 404 participants aged between 18 and 90 years (males = 187, females = 217). The average endothelial cell density was 2763.6 cells/mm2, and there was a decrease in endothelial cell density with increasing age, irrespective of gender. There was no significant difference in endothelial cell density between males and females. Increasing age (adjusted coefficient - 10.1, p < 0.001), history of smoking (adjusted coefficient - 439.6, p = 0.004), history of ocular surgery (adjusted coefficient - 168.0, p = 0.023), having dry eye (adjusted coefficient - 136.0, p = 0.051), and having arcus senilis (adjusted coefficient - 132.0, p = 0.08), were correlated with lower endothelial cell density. However, increasing corneal diameter (adjusted coefficient 134.0, p = 0.006), increasing central corneal thickness (adjusted coefficient 1.2, p = 0.058), and increasing axial length (adjusted coefficient 65.8, p = 0.026), were correlated with higher endothelial cell density. We found five eyes (0.63%) from different participants with a low endothelial cell density (< 1000cells/mm2).

CONCLUSION

Our study established baseline normal ranges of ECD in a predominantly black African population, and found that low ECD is rare in our population. The elderly, smokers, and those with past ocular surgery are the most vulnerable. The low prevalence could be due to a lack of reference values for the black African population.

Analysis of cardiovascular risk factors for the viability of cornea donors: a case-control study

OBJECTIVE

The main objective of the study was to evaluate the influence of arterial hypertension, diabetes, dyslipidaemia, smoking, alcoholism and COPD (chronic obstructive pulmonary disease) on the viability of the extracted tissue as well as the donor.

DESIGN

Observational case-control study.

SETTING

Regional hospital in Northern Spain.

PARTICIPANTS

1517 corneas were registered.

INTERVENTIONS

Patients' medical history was reviewed after corneal donation and evaluation. Previous medical information (age, sex and cardiovascular risk factors (CVRFs)) and data related to the donor (type of donor), the corneal tissue and its evaluation, and the viability of the implant were collected.

RESULTS

A total of 1517 corneas were registered and 81.5% of the donors presented at least one CVRF. In relation to the viability of the donor, it was observed that having suffered from COPD reduced the viability of the donor (no COPD: 93.8% vs COPD: 88%; OR=0.49; 95% CI: 0.28 to 0.84) while alcohol consumption increased it (drinker or ex-drinker: 95.8% vs non-drinker: 92.5%; OR=1.84; 95% CI: 1.01 to 3.33). Regarding tissue viability, decreased viability was observed in the presence of COPD (no COPD: 72.5% vs COPD: 64; OR=0.67; 95% CI: 0.47 to 0.96) and diabetes mellitus (no diabetes: 72.9% vs diabetes: 67.2%; OR=0.76; 95% CI: 0.58 to 0.99). As regards the viability of the implant, a total of 1039 corneas (68.9%) were suitable, observing decreased viability when suffering from COPD (no COPD: 69.8% vs COPD: 60.7%; OR=0.67; 95% CI: 0.47 to 0.94) and increased when having an active smoking habit (no habit: 65.3% vs habit: 74.1%; OR=1.52; 95% CI: 1.21 to 1.91).

CONCLUSIONS

Through this study, it can be concluded that in the absence of absolute exclusion criteria for donors, the assessment of how CVRF, alcoholism and COPD may affect the donor provides details about the quality of the tissue to be obtained.

Preserflo MicroShunt: Efficacy and Endothelial Cell Density

PRCIS

A main safety concern associated with new glaucoma implants is corneal endothelial cell loss, which could even be observed in already established procedures.

PURPOSE

The purpose of this study was to evaluate the efficacy and corneal safety, especially corneal endothelial cell loss (ECL), after Preserflo MicroShunt implantation.

METHODS

A monocentric, prospective clinical observational study of patients with a follow-up of at least 12 months who underwent Preserflo MicroShunt implantation at the Department of Ophthalmology, University Hospital of Düsseldorf, Germany, between January 2020 and October 2021. Endothelial cell density (ECD), the distance between the tip of the implant and the corneal endothelium, and the success of the surgery were analyzed.

RESULTS

In total, 14 eyes of 12 patients were included. After a mean follow-up of 20±2.7 months intraocular pressure was significantly reduced by 8.2 mm Hg (P=0.0041); in 28.6% of patients, a revision surgery was necessary. Reduction of preoperative and follow-up ECD was not statistically significant (ECL of 45 cells/mm2, ECDpreoperative=2074±703.6 cells/mm2, ECDlast follow-up=2029±742.3 cells/mm2, P=0.42). A longer intracameral shunt tube length correlated significantly with a higher distance between the shunt tip and corneal endothelium (r=0.61, P=0.036).

CONCLUSIONS

Preserflo MicroShunt effectively lowered intraocular pressure without substantial ECL after a minimum follow-up period of 17 months.

Corneal characteristics and OCT-angiography findings in pediatric glaucoma and glaucoma suspects

PURPOSE

To analyze corneal biomechanics, specular microscopy, and optical coherence tomography-angiography findings in children with glaucoma.

METHODS

Pediatric patients (<18 years of age) with glaucoma (n = 38), increased cup:disk ratio and normal intraocular pressure (IOP) glaucoma suspects (n = 36), and controls (n = 67) were prospectively enrolled. Patients underwent testing with Ocular Response Analyzer, CellChek Specular Microscope, and Heidelberg OCT-A.

RESULTS

Average age of participants was 12.4 ± 3.5 years, with no difference between groups (P = 0.71). Glaucoma patients had undergone more intraocular surgeries (P < 0.0001) and showed worse logMAR visual acuity (P < 0.0001) than suspects or controls. Central corneal thickness (CCT) was greater in glaucoma patients (642.8 ± 85.9 μm [P < 0.0001]) and suspects (588 ± 43.7 μm [P = 0.003]) compared with controls (561 ± 39.9 μm). Corneal hysteresis (CH) was decreased in eyes with glaucoma (10.4 ± 3.0) compared with controls (11.7 ± 1.5 [P = 0.006]), but not suspects (11.3 ± 2.0 [P = 0.1]). Glaucoma patients had lower endothelial cell density (2028.4 ± 862.7 [P < 0.0001]) and greater average cell area (547.2 ± 332.4 [P < 0.0005]) compared with suspects (2919.3 ± 319.1, 347.5 ± 46.2) and controls (2913.7 ± 399.2, 350.8 ± 57.7), but there was no difference in polymegathism (P = 0.12) or pleomorphism (P = 0.85). No differences in vessel density or vessel skeletal density in the retinal vascular complex (P = 0.3077, P = 0.6471) or choroidal vascular complex (P = 0.3816, P = 0.7306) were detected.

CONCLUSIONS

Children with glaucoma showed thicker corneas with lower endothelial cell density and greater cell area, but no difference in retinal/choroidal vascular densities compared with suspects and controls.

Changes in corneal endothelial cell density after trabeculectomy

BACKGROUND

Glaucoma is a leading cause of blindness worldwide for which trabeculectomy is the most effective surgical intervention for advanced disease. However, trabeculectomy has been associated with alterations to corneal endothelium, including a decrease in corneal endothelial cell density (CECD). The purpose of this study was to investigate changes in CECD after trabeculectomy, and identify factors contributing to cell loss, such as pre-operative biometry and lens status.

METHODS

This retrospective study included 72 eyes of 60 patients who underwent trabeculectomy between January 2018 and June 2021 at two private hospitals. Demographic and clinical data were obtained at baseline. Corneal specular microscopy was performed pre-operatively and at 6 months after surgery. CECD was evaluated and compared between groups to quantify changes to corneal endothelium and identify significant factors affecting decreases in cell density.

RESULTS

Mean CECD was 2284.66 ± 375.59 pre-operatively and 2129.52 ± 401.96 after 6 months (p < 0.001). A greater decrease in CECD (p = 0.005) was observed in phakic eyes (235.45 ± 118.32) compared to pseudophakic eyes (137.82 ± 107.30). The amount of cell loss was negatively correlated with pre-operative central corneal thickness (p = 0.009) and anterior chamber (AC) depth (p = 0.033). There were no significant correlations between changes to CECD and patient age, gender, number of pre-operative glaucoma medications and number of post-operative antifibrotic agents.

CONCLUSIONS

Significant decreases in CECD occurred after trabeculectomy. Less corneal endothelial cell loss occurred in pseudophakic eyes. Hence, if patients need trabeculectomy and cataract surgery, it may be better to perform cataract surgery first. Longer term studies should derive more information.

Risk factors associated with corneal endothelial cell density in Posner-Schlossman syndrome

PURPOSE

To investigate the risk factors related to corneal endothelial cell density (ECD) in patients with Posner-Schlossman syndrome (PSS).

PATIENTS AND METHODS

It was an observational retrospective study. We reviewed the medical records of patients with PSS who attended the ophthalmology department at Wuhan University Zhongnan Hospital from January 2019 to December 2021. 42 eyes of 42 patients with PSS were included in the study. Demographic characteristics and clinical manifestations were recorded. The clinical characteristics of PSS patients with reduced ECD were compared with PSS patients with normal ECD. Simple and multiple linear regression analyses were carried out to identify the risk factors for ECD in PSS.

RESULTS

The ECD-lowered group had a longer disease duration (P = 0.000), higher rate of occurrence of corneal edema (P = 0.039), higher cytomegalovirus (CMV) deoxyribonucleic acid (DNA) copy number (P = 0.044), higher interleukin-10 (IL-10) level in the aqueous humor (P = 0.044), and thinner average retinal nerve fiber layer (RNFL) thickness (P = 0.016) than the control group. The results of multiple linear regression analysis indicated that disease duration (β =  - 0.287, P = 0.024) and level of IL-10 in the aqueous humor (β =  - 0.408, P = 0.001) were significantly negatively associated with ECD, while average RNFL thickness (β = 0.330, P =  0.007) was significantly positively related to ECD in PSS.

CONCLUSION

A longer disease duration, higher degree of glaucomatous damage and elevated level of IL-10 in the aqueous humor were associated with reduced ECD in PSS.

Corneal Endothelial Cell Loss in Patients After Minimally Invasive Glaucoma Surgery: Current Perspectives

Minimally invasive glaucoma surgery (MIGS) is a rapidly expanding category of surgical glaucoma treatment options that offer a superior safety profile compared with traditional approaches for reducing intraocular pressure. However, MIGS may cause corneal endothelial cell loss; therefore, it has been receiving increasing attention. This systematic review aimed to evaluate and compare the rate and degree of corneal endothelial loss after MIGS. First, this paper presents an overview of the theoretical effectiveness of MIGS, the fundamental aspects regarding the roles of endothelial cells, and the effect of cataract surgery on the quality and count of endothelial cells. Further, we detail the various surgical techniques involved in MIGS, the development of these techniques over the time, and clinical aspects to consider with respect to the endothelial cell count. We discuss in detail the COMPASS-XT study, which was based on data collected over 5 years, reported that withdrawal of the CyPass Micro-Stent (Alcon Laboratories) yielded increased corneal endothelial cell loss. Generally, MIGS procedures are considered safe, with the incidence of complications ranging from 1% to 20% depending on the surgery type; however, there is still need for studies with longer follow-up. Thus, an adequate count of endothelial cells in the central cornea portion is recommended as necessary for candidate patients for MIGS.

Interim Analysis of STREAMLINE® Surgical System Clinical Outcomes in Eyes with Glaucoma

Purpose

To characterize the clinical outcomes of a novel ab interno minimally invasive procedure with the STREAMLINE^® Surgical System for creation of incisional goniotomies and canal of Schlemm viscodilation in eyes with mild to severe primary open-angle glaucoma (POAG).

Methods

In a prospective, single-arm, first-in-human case series, 20 eyes of 20 subjects with mild to severe POAG underwent creation of incisional goniotomies and canal of Schlemm viscodilation following phacoemulsification cataract extraction after washout of all intraocular pressure (IOP)-lowering medications. The angle surgery portion was performed with a single-use handpiece tipped with a microcannula that creates precise goniotomies through the trabecular meshwork into the canal of Schlemm and delivers a small volume of ophthalmic viscosurgical device directly into the canal via precise catheterization. Outcomes in this interim analysis included mean reduction in IOP and medications through 6 months of follow-up, as well as the proportion of eyes achieving IOP reduction ≥20% from baseline.

Results

At month 6, mean IOP reduction of ≥20% from baseline was achieved in 89.5% of eyes (17/19). Mean (standard deviation) medicated IOP at screening was 16.3 (3.6) mmHg and unmedicated baseline IOP (after washout) was 23.5 (2.5) mmHg. Mean IOP was significantly reduced from baseline through 6 months of follow-up to 14.7 (2.4) mmHg (p<0.001), representing an IOP reduction of 8.8 mmHg (36.9%). Overall, 57.9% (11/19) of eyes decreased dependence on IOP-lowering medications by at least one medication, and 42.1% (8/19) were medication free. Mean medication use was reduced from 2.0 (0.8) at screening to 1.1 (1.1) at 6 months (p<0.001). Three eyes had transient IOP spikes treated with topical medications.

Conclusion

The creation of incisional goniotomies and canal of Schlemm viscodilation safely and effectively reduced IOP and the need for IOP-lowering medications by both clinically and statistically significant magnitudes in eyes with mild to severe POAG undergoing concomitant phacoemulsification cataract extraction through the first 6 months of follow-up.

Twenty-Four-Month Outcome of Gonioscopy-Assisted Transluminal Trabeculotomy (GATT) in Eyes With Prior Corneal Transplant Surgery

PURPOSE

Glaucoma is a well-known sequelae of corneal transplant surgery and is a leading cause of visual loss in this patient group. We evaluated the performance and safety of gonioscopy-assisted transluminal trabeculotomy (GATT) in this population.

DESIGN

Noncomparative retrospective case series.

PARTICIPANTS

Consecutive eyes of patients receiving the GATT procedure for uncontrolled intraocular pressure (IOP) following corneal transplant surgery from 2016 to 2019.

METHODS

Retrospective analysis of eyes with a history of prior corneal transplant undergoing GATT at Glaucoma Associates of Texas between 2016 and 2019 was performed. Data included IOP, patient demographics, preoperative and postoperative medications, preoperative and postoperative corneal procedures, complications, and need for reoperation for IOP control.

MAIN OUTCOME MEASURES

IOP reduction and medication use following the procedure.

RESULTS

Thirty-nine eyes of 32 patients with prior corneal transplant surgery underwent a GATT procedure. Prior corneal surgery included penetrating keratoplasty (59.0%), Descemet's stripping endothelial keratoplasty (35.9%), Descemet's membrane endothelial keratoplasty (2.6%), and deep anterior lamellar keratoplasty (2.6%). Patient age ranged from 24 to 94 years (mean 68.0 y) with 44% female and 81% Caucasian. The majority of patients had secondary open angle glaucoma (64.1%). There was a significant reduction in IOP and number of medications at all postoperative time points after censoring patients requiring reoperation to control IOP (P<0.001). At 24 months the pressure decreased from baseline of 30.9±11.5 to 13.9±4.7 mm Hg. Medications decreased from 4.2±1.0 medications at baseline to 0.6±1.0 at 24 months. Visual acuities decreased significantly over the first postsurgical month (all P<0.05), but these recovered at subsequent follow-up visits with 2-Snellen line improvements exceeding losses from month 3 to 36. Seven eyes required reoperation for uncontrolled glaucoma at a median of 8.5 months (range: 1.6 to 16.2 mo) after GATT. The cumulative proportion of eyes undergoing repeat cornea surgery was 2.6%, 2.6%, and 14.3% at 12, 24, and 36 months post-GATT, respectively.

CONCLUSIONS

This case series describes a group of glaucoma patients, with a history of prior corneal surgery, that were safely and successfully treated with GATT. While classically traditional glaucoma surgeries are considered the standard of care for eyes following corneal transplant surgery, GATT should be considered as a reasonable, safe and effective alternative for surgically lowering IOP.

The effects of acute angle closure crisis on corneal endothelial cells in patients with type 2 diabetes mellitus

OBJECTIVE

This study investigated the effects of acute angle closure crisis (AACC) on the corneal endothelial cells in patients with type 2 diabetes mellitus (DM) to identify the factors that cause corneal endothelial cell injury.

METHODS

We examined 154 patients who visited Qingdao Eye Hospital for AACC in one eye (154 eyes; 28 men and 126 women; mean age of 68 ± 8 years). We divided the participants into non-DM, DM well-control, and DM poor-control groups, with the unaffected eyes used as controls. Each participant was evaluated at the hospital while under AACC. We measured the relevant index and corneal parameters of the participants for statistical analysis.

RESULTS

There were significant statistical differences in corneal parameters among the three groups. The decreased levels of central endothelial cell density (CD) and the percentage of hexagonal cells (6A) were statistically relevant among the groups (P<0.05). The AACC duration was correlated with CD loss rate among the groups (P<0.05). The DM duration was correlated with CD loss rate in the DM well-control group. Compared with the non-DM group, the level of 6A decreased more significantly in the DM group after AACC (P<0.05). The AACC duration in the DM well-control group was significantly shorter than in the non-DM and DM poor-control groups (P<0.001). The DM poor-control group showed significantly worse visual acuity when compared with the other groups (P<0.05).

CONCLUSIONS

DM may impact the functional status of corneal endothelial cells. AACC can worsen the corneal endothelium damage in patients with DM. Blood glucose levels and the duration of intraocular hypertension are closely related to the severity of corneal endothelial injury.

Risk factors for fluctuations in corneal endothelial cell density (Review)

The cornea is a transparent, avascular and abundantly innervated tissue through which light rays are transmitted to the retina. The innermost layer of the cornea, also known as the endothelium, consists of a single layer of polygonal endothelial cells that serve an important role in preserving corneal transparency and hydration. The average corneal endothelial cell density (ECD) is the highest at birth (~3,000 cells/mm²), which then decrease to ~2,500 cells/mm² at adulthood. These endothelial cells have limited regenerative potential and the minimum (critical) ECD required to maintain the pumping function of the endothelium is 400-500 cells/mm². ECD < the critical value can result in decreased corneal transparency, development of corneal edema and reduced visual acuity. The condition of the corneal endothelium can be influenced by a number of factors, including systemic diseases, such as diabetes or atherosclerosis, eye diseases, such as uveitis or dry eye disease (DED) and therapeutic ophthalmological interventions. The aim of the present article is to review the impact of the most common systemic disorders (pseudoexfoliation syndrome, diabetes mellitus, cardiovascular disease), eye diseases (DED, uveitis, glaucoma, intraocular lens dislocation) and widely performed ophthalmic interventions (cataract surgery, intraocular pressure-lowering surgeries) on corneal ECD.

Corneal Endothelial Cell Loss After PRESERFLO™ MicroShunt Implantation in the Anterior Chamber: Anterior Segment OCT Tube Location as a Risk Factor

INTRODUCTION

To analyze the effects of PRESERFLO on corneal endothelial cell density (ECD).

METHODS

Forty-six eyes that underwent PRESERFLO implantation were followed up for 12 months. Specular microscopy was performed preoperatively and at 1, 3, 6, and 12 months postoperatively to measure central ECD and mean monthly reduction (MMR). Anterior segment optical coherence tomography (AS-OCT) was applied to measure the tube-endothelium (TE < 200 μm, 201-500 μm, > 500 μm) distance. The relationship between TE distance and ECD was analyzed with a linear mixed-effects model.

RESULTS

Central ECD decreased significantly at 1 year (7.4%, p = 0.04), with an MMR of -15 ± 25 cells/mm². Regarding TE distance groups, there was an 18% ECD reduction in the < 200 μm group vs. 1% in the > 500 μm group (p = 0.08). Endothelial cell loss was related to TE distance (mean 482.9 ± 238 μm), with a higher rate at 1 month in comparison to 12 months for the same tube position in the anterior chamber (-174.8 ± 65.2 cells/mm² at 1 month vs. 30.2 ± 11.3 cells/mm² at 12 months, p < 0.01). From month 6, tubes located > 600 μm from the endothelium showed EC loss close to zero.

CONCLUSIONS

The PRESERFLO implant is associated with a loss of EC from the immediate postoperative period that continues over time at lower rates. A shorter TE distance appears to cause more severe ECD loss.

Evaluation of the Effect of the First Generation iStent on Corneal Endothelial Cell Loss-A Match Case-Control Study

Glaucoma is the leading cause of irreversible blindness worldwide. The only proven factor in slowing the progression of glaucomatous neuropathy is lower intraocular pressure (IOP), which can be achieved with pharmacology, laser therapy, or surgery. However, these treatments are associated with various adverse effects, including corneal endothelial cell loss (CECL). In recent years, several novel surgeries for reducing the IOP, collectively referred to as minimally invasive glaucoma surgery (MIGS), have been developed, one of which is the iStent. However, the long-term effects of such surgeries remain unknown. We compared a group of patients with open-angle glaucoma and cataract who underwent phacoemulsification alone with a group of patients with similar demographic and clinical characteristics who underwent simultaneous phacoemulsification and iStent implantation. Overall, 26 eyes of 22 subjects who underwent a combined phacoemulsification-iStent procedure and 26 eyes of 24 subjects who underwent cataract surgery were included. Before surgery, endothelial cells accounted to 2228.65 ± 474.99 in iStent group and 2253.96 ± 404.76 in the control group (p = 0.836). After surgery, their number declined to 1389.77 ± 433.26 and 1475.31 ± 556.45, respectively (p = 0.509). There was no statistically significant difference in CECL between the two groups 18–24 months after surgery, despite increased manipulation in the anterior chamber and the presence of an implant in the trabecular meshwork in those with an iStent implant. Thus, iStent bypass implantation is a safe treatment in terms of CECL for mild-to-moderate open-angle glaucoma.