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

Research progress on the impact of cataract surgery on corneal endothelial cells

Background

Cataracts are a common eye disease and a major cause of blindness in China and worldwide. In China, the incidence of cataracts among people over 60 years old is as high as 80%. Surgery is the primary treatment for various types of cataracts, but such invasive procedures can affect corneal endothelial cells to some extent.

Content

Cataract surgery can damage corneal endothelial cells, leading to complications such as corneal edema in mild cases. Severe damage can result in endothelial decompensation, necessitating secondary corneal endothelial transplantation. Preoperative thorough assessment of endothelial status, intraoperative endothelial protection measures, and postoperative active use of medications to prevent further damage to endothelial cells can reduce endothelial cell loss. Factors influencing endothelial cell status include whether the patient has related systemic diseases or ocular conditions, the hardness of the nucleus, the choice of surgical incision, the method of nuclear fragmentation, the type of viscoelastic agent used, the orientation of the phacoemulsification needle bevel, the duration and energy of ultrasound use, the choice of fluid control system, the use of protective auxiliary instruments, the application of intraocular lens scaffold technology, femtosecond laser assistance, and the use of certain medications.

Conclusions

Actively regulating the factors affecting corneal endothelial cells to reduce damage related to cataract surgery is crucial. This paper reviews the existing literature on various factors affecting corneal endothelial cells during cataract surgery and explores future developments and research directions.

PRESERFLO MicroShunt in Severe Myopia: A Case Report and Review of the Literature

The PRESERFLO™ MicroShunt (MP; Santen Inc., Osaka, Japan) is a minimally invasive bleb surgery (MIBS) manufactured to treat primary open-angle glaucoma (POAG), with lower postoperative adverse effects than with conventional filtering surgeries. We describe here the case study of a 58-year-old woman who presented with bilateral severe myopia with bilateral advanced POAG and unreached target pressure under quadritherapy, who was successfully managed by PM surgery. A review of the literature completes our observation. At presentation, the patient had a spherical equivalent of - 7.50 RE and - 7.75 LE with an IOP of 22 mmHg right and left eye (RLE) under quadritherapy, and with severe bilateral visual field loss, including scotomas within the central 5°. The patient presented with systemic hypertension treated with an antihypertensive drug. Two selective laser trabeculoplasties (SLT), performed 3 months apart, were first tried on the LE, without any change in IOP at 2 months. After considering the high risk of postoperative complications, a PM operation was proposed, with a targeted IOP in the mid-fifteens RLE. The patient's eyes underwent PM surgery with mitomycin C (MMC) MMC0.2 mg/mL for 3 minutes without any complications. The LE required 2 consecutive needlings with 1 mL MMC0.2 mg/mL. At 24 months after surgery, the two eyes gave successful results without the need for any additional medical therapy, and with well-functioning conjunctival blebs. The PM was an effective alternative to the gold standard trabeculectomy in our severely myopic patient. A comparative study between conventional filtering operations and this MIBS in highly myopic patients would confirm our observation.

Potential applications of artificial intelligence in image analysis in cornea diseases: a review

Artificial intelligence (AI) is an emerging field which could make an intelligent healthcare model a reality and has been garnering traction in the field of medicine, with promising results. There have been recent developments in machine learning and/or deep learning algorithms for applications in ophthalmology-primarily for diabetic retinopathy, and age-related macular degeneration. However, AI research in the field of cornea diseases is relatively new. Algorithms have been described to assist clinicians in diagnosis or detection of cornea conditions such as keratoconus, infectious keratitis and dry eye disease. AI may also be used for segmentation and analysis of cornea imaging or tomography as an adjunctive tool. Despite the potential advantages that these new technologies offer, there are challenges that need to be addressed before they can be integrated into clinical practice. In this review, we aim to summarize current literature and provide an update regarding recent advances in AI technologies pertaining to corneal diseases, and its potential future application, in particular pertaining to image analysis.

The effect of irrigation and aspiration on the corneal endothelial cell density in patients undergoing Implantable Collamer Lens with a central hole implantation for myopia correction

PURPOSE

In the conventional technique, viscoelastic agents are typically rinsed away with balanced salt solution (BSS), but it may lead to a series of complications such as viscoelastic residue, anterior chamber instability and intraoperative TICL rotation. The utilization of irrigation and aspiration (I/A) has been shown to be effective in maintaining anterior chamber stability, reducing the incidence of postoperative high intraocular pressure, and minimizing postoperative fundus complications. However, there is a lack of previous studies investigating the impact of I/A on corneal endothelial cells during ICL implantation. The objective of this study was to examine the effect of I/A on corneal endothelial cells in patients undergoing myopia correction through implantation of Implantable Collamer Lens with a central hole (V4c ICL).

METHODS

A retrospective selection was made of 344 eyes from 172 patients who underwent V4c ICL implantation and I/A to remove viscoelastic agent from the anterior chamber between 2021 and 2022. The intraocular pressure (IOP) was measured at 1 h, 2 h and 3 h after surgery. Corneal endothelial cell density (ECD), coefficient of variation in cell size (CV), standard deviation of cell area (SD), and percentage of hexagonal cells (HEX) were evaluated at 1 week postoperatively to assess corneal endothelial cells. The first two represent polymegethism or morphological variation, while the third parameter represents the degree of polymorphism of the corneal endothelial cells. Electronic medical records were utilized for data collection purpose.

RESULTS

All surgeries proceeded without complications. The IOP was 16.50 ± 3.42 mmHg (range: 11.5-22.3 mmHg) prior to surgery and increased to 21.25 ± 5.61 mmHg (range: 9.5-34.8 mmHg), 19.85 ± 5.18 mmHg (range: 11.4-36.2 mmHg) and finally settled at an average of 18.81 ± 4.57 mmHg (range: 10.1-38.8 mmHg) at the respective time points of 1 h, 2 h and 3 h after surgery. The preoperative ECD was recorded as being approximately 3004 ± 295 cell/mm2, which exhibited a marginal decreased of 1.17% postoperatively, resulting in an average ECD value of 2969 ± 303 cell/mm2 one week after surgery (P = 0.12). Similarly, the preoperative CV was determined as 31.10 ± 3.78%, and it experienced a slight reduction with an average CV value of 30.74 ± 3.77% at week after surgery (P = 0.21). And, the preoperative SD was reported as 104.76 ± 17.26, and it remained virtually unchanged with an average SD value of 104.85 ± 18.75 at one week after surgery (P = 0.95). The preoperative HEX was calculated as 55.38 ± 8.94%, and it remained its stability with an average HEX value of 55.45 ± 8.73% one week after surgery (P = 0.92).

CONCLUSION

The utilization of I/A led to a slight decrease in postoperative ECD when compared to conventional surgical techniques. Nevertheless, the reduction in ECD remained within acceptable limits, taking into accout the avervantaged it offered, such as stabilization of the anterior chamber and decreased occurrence of viscoelastic residue after surgery. It is challenging to anticipate the long-term safety of corneal endothelial cells based on current short-term studies. However, this study provides a valuable reference indicating that neither anterior chamber irrigation nor I/A aspiration have an adverse impact on the safety of corneal endothelial cells in the short term. Further research is imperative to enhance our understanding of their effects over an extended period.

A computational fluid dynamics investigation of endothelial cell damage from glaucoma drainage devices

Glaucoma drainage devices (GDDs) are prosthetic-treatment devices for treating primary open-angle glaucoma. Despite their effectiveness in reducing intraocular pressures (IOP), endothelial cell damage (ECD) is a commonly known side-effect. There have been different hypotheses regarding the reasons for ECD with one being an induced increase in shear on the corneal wall. A computational fluid dynamics (CFD) model was used to investigate this hypothesis in silico. The Ahmed Glaucoma Valve (AGV) was selected as the subject of this study using an idealised 3D model of the anterior chamber with insertion angles and positions that are commonly used in clinical practice. It was found that a tube-cornea distance of 1.27 mm or greater does not result in a wall shear stress (WSS) above the limit where ECD could occur. Similarly, a tube-cornea angle of 45° or more was shown to be preferable. It was also found that the ECD region has an irregular shape, and the aqueous humour flow fluctuates at certain insertion angles and positions. This study shows that pathological amounts of WSS may occur as a result of certain GDD placements. Hence, it is imperative to consider the associated fluid force interactions when performing the GDD insertion procedure.

Unexpected findings: loss of corneal endothelial cells in Uygur patients with exfoliation syndrome

PURPOSE

This study aimed to investigate anterior segment parameters in patients with exfoliation syndrome (XFS) and exfoliation glaucoma (XFG).

METHODS

The study adopted a retrospective case series design, involving a total of 56 patients (112 eyes) with unrelated XFS/XFG (XFS: 26 patients/60 eyes; XFG: 30 patients/44 eyes) and 100 age-related cataract cases as the control group (200 eyes). The participants were evaluated at the ophthalmology department of the First Affiliated Hospital of Xinjiang Medical University. Clinical data, including eye axial length, anterior chamber depth, white-to-white distance, central corneal thickness, and corneal endothelial cell density (ECD), were collected for statistical analysis.

RESULTS

ECD exhibited a significant difference between the XFS/XFG and age-related cataract groups (P < 0.001), while the remaining indexes did not show statistical differences (P > 0.05). Ocular parameters in patients with XFS and XFG were distinct from those in age-related cataract cases, with consistent results. Notably, there were no statistically significant differences between XFS and XFG patients.

CONCLUSIONS

ECD is reduced in XFS/XFG patients compared with age-related cataract subjects. It is crucial to remain vigilant to enhance surgical safety in XFS/XFG patients and prevent complications proactively.

EZH2 Promotes Corneal Endothelial Cell Apoptosis by Mediating H3K27me3 and Inhibiting HO-1 Transcription

PURPOSE

This paper aims to explore the molecular mechanism of Enhancer of Zeste Homolog 2 (EZH2)-mediated H3K27me3 in human corneal endothelial cells (HCEC) apoptosis by inhibiting Heme oxygenase-1 (HO-1) transcription to provide a potential target for the treatment of corneal apoptosis.

METHODS

HCECs were cultured in vitro and transfected with si-EZH2, pcDNA3.1-EZH2, pcDNA3.1-HO-1, GSK-J4 (an effective H3K27me3 demethylase inhibitor), and corresponding controls. Western Blot assay was used to detect the levels of EZH2, HO-1, H3K27me3, and apoptosis-related proteins (Bcl-2, Bax, and Cleaved-caspase-3) in HCECs; CCK-8 assay was conducted to detect cell viability and flow cytometry to analyze the apoptosis. HO-1 mRNA levels were detected by RT-qPCR and changes in H3K27me3 levels on the HO-1 promoter were detected by chromatin immunoprecipitation.

RESULTS

HCECs transfected with si-EZH2 showed significantly lower EZH2 mRNA and protein levels, higher HCEC viability, lower apoptosis rates, higher antiapoptotic protein Bcl-2 expression, lower proapoptotic protein (Bax and Cleaved-caspase-3) levels, and significantly higher HO-1 expression. HCECs transfected with pcDNA3.1-EZH2 showed the opposite results. EZH2 repressed HO-1 transcription by mediating H3K27me3. H3K27me27 was enriched in the HO-1 promoter and overexpression of EZH2 increased H3K27me27 levels. Promotion of H3K27me3 partially reversed the mitigating effect of si-EZH2 on HCEC apoptosis. Overexpression of HO-1 partially reversed the apoptosis-promoting effects of EZH2 and H3K27me3 on HCECs.

CONCLUSIONS

EZH2 promotes HCE cell apoptosis by mediating H3K27me3 to inhibit HO-1 transcription.

Single Administration of Bimatoprost Implant: Effects on 24-Hour Intraocular Pressure and 1-Year Outcomes

PURPOSE

To evaluate the effects of a single bimatoprost implant administration on 24-hour intraocular pressure (IOP) lowering at 8 weeks, and 1-year IOP-lowering efficacy and safety outcomes.

DESIGN

Multicenter, open-label, 12-month, phase 3b study (NCT04285580).

PARTICIPANTS

Adults with open-angle glaucoma or ocular hypertension.

METHODS

Participants (n = 31) received 10-μg bimatoprost implant in the study eye on day 1; IOP (sitting and/or supine) was measured with pneumatonometry every 2 hours throughout a 24-hour period at baseline and week 8. IOP was measured by Goldmann applanation tonometry (GAT) at hour 0 (8 am ± 1 hour) at baseline, weeks 8 and 16, and months 6, 9, and 12.

MAIN OUTCOME MEASURES

The primary endpoint was the week-8 hour-matched change from baseline in habitual position IOP over 24 hours assessed with pneumatonometry. Hour 0 IOP change from baseline measured with GAT in study eyes that received no additional (rescue) IOP-lowering treatment, treatment-emergent adverse events (TEAEs), and central corneal endothelial cell density (CECD) were evaluated through 12 months.

RESULTS

The mean (standard deviation [SD]) baseline IOP at hour 0 was 24.2 (2.70) mmHg and 25.3 (7.15) mmHg by GAT and pneumatonometry, respectively. Pneumatonometer measurements of IOP taken over 24 hours at week 8 with the participant in habitual position (sitting from 8 am to 10 pm, supine from 12 am to 6 am) showed consistent IOP lowering through the day and night and reduced fluctuation in IOP. The range in IOP measurements over 24 hours was reduced from baseline by a mean (SD) of -1.6 (2.98) mmHg. All 31 bimatoprost implant-treated participants completed the 12-month study; 23 (74%) required no rescue IOP-lowering treatment. The mean (SD) IOP reduction from baseline at month 12 in nonrescued eyes was -4.3 (3.35) mmHg. The most common TEAE was conjunctival hyperemia (incidence 35.5%, 11/31). No implant-treated eye had a ≥ 15% loss in CECD from baseline.

CONCLUSIONS

A single intracameral administration of the bimatoprost implant lowered IOP in the habitual position consistently throughout the day and night at week 8. The majority of participants continued to have reduced IOP for 1 year without additional therapy. The 1-year safety profile was favorable.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Particular Anatomy of the Hyperopic Eye and Potential Clinical Implications

Background and Objectives: Hyperopia is a refractive error which affects cognitive and social development if uncorrected and raises the risk of primary angle-closure glaucoma (PACG). Materials and Methods: The study included only the right eye-40 hyperopic eyes in the study group (spherical equivalent (SE) under pharmacological cycloplegia over 0.50 D), 34 emmetropic eyes in the control group (SE between -0.50 D and +0.50 D). A complete ophthalmological evaluation was performed, including autorefractometry to measure SE, and additionally we performed Ocular Response Analyser: Corneal Hysteresis (CH), Corneal Resistance Factor (CRF); specular microscopy: Endothelial cell density (CD), Cell variability (CV), Hexagonality (Hex), Aladdin biometry: Anterior Chamber Depth (ACD), Axial Length (AL), Central Corneal Thickness (CCT). IBM SPSS 26 was used for statistical analysis. Results: The mean age of the entire cohort was 22.93 years (SD ± 12.069), 66.22% being female and 33.78% male. The hyperopic eyes had significantly lower AL, ACD, higher SE, CH, CRF. In the hyperopia group, there are significant, negative correlations between CH and AL (r -0.335), CRF and AL (r -0.334), SE-AL (r -0.593), ACD and CV (r -0.528), CV and CRF (r -0.438), CH (r -0.379), and positive correlations between CCT and CH (r 0.393) or CRF (r 0.435), CD and ACD (r 0.509) or CH (0.384). Age is significantly, negatively correlated with ACD (r -0.447), CH (r -0.544), CRF (r -0.539), CD (r -0.546) and positively with CV (r 0.470). Conclusions: Our study suggests a particular biomechanical behavior of the cornea in hyperopia, in relation with morphological and endothelial parameters. Moreover, the negative correlation between age and ACD suggests a shallower anterior chamber as patients age, increasing the risk for PACG.

Clinical Differences between Posner-Schlossman Syndrome Patients with Intermittent Intraocular Pressure Elevation and Glaucomatous Damage

INTRODUCTION

Although there is abundant evidence that Posner-Schlossman syndrome (PSS) can lead to secondary glaucoma, data on the clinical differences between PSS patients with secondary glaucoma and those with intermittent intraocular pressure (IOP) elevation are sparse.

METHODS

This retrospective observational study included 52 patients (52 eyes) diagnosed with PSS and admitted to Zhongnan Hospital of Wuhan University between January 2019 and February 2022. Demographic characteristics and clinical features were gathered from admission records. Patients were divided into two groups: 27 cases with intermittent IOP elevation (group A) and 25 cases with secondary glaucoma (group B and C). Of the secondary glaucoma cases, 18 were further divided into the topical IOP-lowering medications group (group B) and 7 into the glaucoma surgery group (group C). Clinical characteristics of different groups were compared.

RESULTS

Compared to the intermittent IOP elevation group, PSS patients with secondary glaucoma had a longer course of disease, a higher incidence of iris depigmentation, lower best corrected visual acuity, lower endothelial cell density, and higher interferon-γ (IFN-γ) concentration and cytomegalovirus (CMV) deoxyribonucleic acid (DNA) copy number in the aqueous humor (all p < 0.05). Group C presented a higher CMV DNA copy number in the aqueous humor than groups A and B (p < 0.05). Compound trabeculectomy proved effective in group C, with a functional filter bleb and well-controlled IOP without disease progression after 1 year of follow-up.

CONCLUSION

Distinctive characteristics existed between PSS patients with secondary glaucoma and those with intermittent IOP elevation. Compound trabeculectomy appears to be an effective treatment option when IOP cannot be controlled through topical medications.

Comparison of corneal endothelial cell loss during manual small-incision cataract surgery using viscoelastic-assisted nucleus removal versus continuous balanced salt solution plus technique - Randomized controlled trial

Purpose

The purpose of this study was to compare and analyze the endothelial cell loss during manual small-incision cataract surgery (MSICS) using the viscoelastic-assisted nucleus removal versus basal salt solution plus technique.

Methods

This was a prospective randomized trial of 204 patients who underwent MSICS using viscoelastic-assisted nucleus removal (Group 1- OVD) versus basal salt solution plus technique (Group 2- BSS) at a tertiary eye care hospital in North India from January 2018 to 2021. Of these 204 patients, 103 (50.5%) and 101 (49.5%) were allocated to Group 1 and 2, respectively. The parameters assessed were detailed history, demographics, and anterior and posterior segment details. Visual acuity, intraocular pressure (IOP), keratometry, pachymetry, and endothelial cell density were evaluated preoperatively and postoperatively on day 1 and 30.

Results

The mean age of the patients was 64.5 ± 8.2 years (range 48-82 years). There were 129 (63.2%) males and 75 (36.8%) females. The mean LogMAR visual acuity for both groups on day 1 (Group 1- 0.3 ± 0.1, Group 2- 0.5 ± 0.2) and day 30 (Group 1- 0.1 ± 0.2, Group 2- 0.1 ± 0.1) was statistically significant (P &lt; 0.001), and the mean IOP value showed a statistically significant value (P &lt; 0.009) on day 1 in Group 2 (15.0 ± 2.4 mmHg) and on day 30 (P &lt; 0.001) in both the groups (Group 1- 13.6 ± 1.8 mmHg, Group 2- 13.5 ± 2 mmHg). The horizontal and vertical k values also showed a statistically significant difference on day 1 and day 30 (P &lt; 0.001). The mean percentage change of central corneal thickness (CCT) in Group 1 was 17.7% and in Group 2 was 17.4% on day 1, and it was 1.1% on day 30 in both the groups, which was statistically significant (P &lt; 0.001) compared to preoperative values. The percentage change in endothelial cell density on day 1 was 9% in Group 1 and 4.6% in Group 2, which was statistically significant (P &lt; 0.001). On day 30, it was 9.7% and 4.8%, respectively, which was statistically significant (P &lt; 0.001).

Conclusion

Our study highlights statistically significant endothelial cell loss with viscoelastic-assisted nuclear delivery compared to BSS-assisted nuclear delivery during MSICS in a short follow-up of 1 month. The CCT values showed a slight increase, and the keratometry and IOP were unaffected compared to the preoperative parameters in both the groups.

Phakic intraocular lenses: an update and review for the treatment of myopia and myopic astigmatism in the United States

PURPOSE OF REVIEW

To review all phakic intraocular lenses (pIOLs) available in the United States for the correction of myopia or myopic astigmatism and offer a clinical approach to their proper use, postoperative follow-up, and analysis of visual and adverse outcomes.

RECENT FINDINGS

In March 2022, the FDA approved the EVO/EVO+ Visian ICL for widespread use, adding this lens to the two others available (Verisyse, Visian ICL). Cataract formation, endothelial cell loss (ECL) and surgical reintervention remain the most common adverse events. There are discrepancies between studies on ECL following implantation with pIOLs, although trends can be deduced with meta-analysis. Posterior Chamber-pIOLs (PC-pIOLs), especially the EVO/EVO+, have an overall lower mean adverse effect and subjective patient symptom profile when compared to Iris Fixated-pIOLS (IF-pIOLs). Advancements in PC-pIOL sizing have provided a noticeable difference in visual and safety outcomes.

SUMMARY

All pIOLs available in the United States provide high-quality visual correction of moderate to high myopia and/or myopia with astigmatism. Proper follow-up for ECL and cataract formation is warranted.

Clinical Outcomes in Maximum Tolerated Medical Therapy in Penetrating Keratoplasty for Bullous Keratopathy

Purpose

To compare the clinical outcomes of maximum tolerated medical therapy (MTMT) in patients with penetrating keratoplasty (PKP) with those of Ahmed glaucoma valve (AGV) implantation.

Methods

The medical records were retrospectively reviewed in patients who had undergone PKP for bullous keratopathy and were treated with MTMT or AGV implantation for the management of glaucoma. A total of 18 bullous keratopathic patients were investigated between January 2010 and February 2017: 9 patients treated with MTMT and 9 patients treated with AGV implantation. Non-corrected visual acuity (NCVA), intraocular pressure (IOP), endothelial cell density (ECD), hexagonality, coefficient of variation (CV), central corneal thickness (CCT), median survival time of the graft, and the presence of epithelial keratopathy were compared between the groups at each time point or between baseline and after treatment of glaucoma in each group.

Results

There were no significant differences in the visual acuity and corneal thickness between the two groups or within each group over time. Both groups showed a significant reduction in IOP compared with the baseline IOP, and IOP reductions were greater in the AGV group than in the MTMT group (p = 0.040). Significant ECD reductions were found in each group between the baseline and 6 months (p = 0.008 in the MTMT group, p = 0.015 in the AGV group); however, no differences were found between the two groups until 12 months. The significant hexagonality reduction was found in the AGV group between the baseline and 12 months (p = 0.018). The median survival time showed no significant difference in the survival analysis.

Conclusions

Maximum tolerated medical therapy in penetrating keratoplasty for bullous keratopathy seems to similarly affect the endothelial cell density or graft survival when compared with at least 12 month-followed Ahmed glaucoma valve implantation.