Long-term changes in endothelial cell counts after early phacoemulsification versus laser peripheral iridotomy using sequential argon:YAG laser technique in acute primary angle closure

Cell therapy in the cornea: The emerging role of microenvironment

The cornea is an ideal testing field for cell therapies. Its highly ordered structure, where specific cell populations are sequestered in different layers, together with its accessibility, has allowed the development of the first stem cell-based therapy approved by the European Medicine Agency. Today, different techniques have been proposed for autologous and allogeneic limbal and non-limbal cell transplantation. Cell replacement has also been attempted in cases of endothelial cell decompensation as it occurs in Fuchs dystrophy: injection of cultivated allogeneic endothelial cells is now in advanced phases of clinical development. Recently, stromal substitutes have been developed with excellent integration capability and transparency. Finally, cell-derived products, such as exosomes obtained from different sources, have been investigated for the treatment of severe corneal diseases with encouraging results. Optimization of the success rate of cell therapies obviously requires high-quality cultured cells/products, but the role of the surrounding microenvironment is equally important to allow engraftment of transplanted cells, to preserve their functions and, ultimately, lead to restoration of tissue integrity and transparency of the cornea.

Efficacy and safety of primary customized phacoemulsification combined with goniosynechialysis for refractory acute primary angle closure

PURPOSE

To assess the safety, efficacy, and long-term clinical outcomes of primary customized phacoemulsification (phaco) combined with goniosynechialysis (GSL; phaco-GSL) in refractory acute primary angle closure (APAC) eyes with uncontrolled high intraocular pressure (IOP).

METHODS

This retrospective case series comprised 51 eyes of 42 consecutive patients with refractory APAC and high IOP who were treated using primary customized phaco-GSL at 3 hospitals in China, from 2014 to 2021. Preoperative and postoperative IOP, corrected distant visual acuity (CDVA), corneal endothelial cell density (CECD), intraoperative and postoperative complications were recorded. The safety, efficacy and subsequent long-term clinical outcomes were analyzed.

RESULTS

The mean CDVA (LogMAR) was improved from 1.67 ± 0.94 preoperatively to 0.23 ± 0.26 postoperatively (P < 0.001). Preoperative CECD was 2309.39 ± 541.03 cells/mm2 in 33 eyes and inaccessible in 18 eyes due to severe corneal edema; at the final follow-up, the mean CECD of all patients was 1823.50 ± 533.40 cells/mm2 (P < 0.001). The mean IOP decreased from 48.51 ± 6.25 mmHg preoperatively to 15.66 ± 2.27 mmHg at the final follow-up (P < 0.001). Among 51 eyes, additional customized procedures performed were corneal indentation in 42 eyes, epithelial debridement in 9 eyes, giant epithelial bullae view in 4 eyes, pars-plana fluid aspiration in 3 eyes, and secondary intraocular lens implantation in 7 eyes. The IOP of all eyes was well controlled eventually and 47 eyes (92.16%) were successfully treated by phaco-GSL alone. No significant intraoperative or postoperative complications were observed.

CONCLUSIONS

Primary customized phaco-GSL is a safe and effective surgical management strategy for patients with refractory APAC and high IOP.

Lens extraction versus laser peripheral iridotomy for acute primary angle closure

BACKGROUND

Acute primary angle closure (APAC) is a potentially blinding condition. It is one of the few ophthalmic emergencies and carries high rates of visual morbidity in the absence of timely intervention. Laser peripheral iridotomy (LPI) has been the standard of care thus far. However, LPI does not eliminate the long-term risk of chronic angle closure glaucoma and other associated sequelae. There has been increasing interest in lens extraction as the primary treatment for the spectrum of primary angle closure disease, and it is as yet unclear whether these results can be extrapolated to APAC, and whether lens extraction provides better long-term outcomes. We therefore sought to evaluate the effectiveness of lens extraction in APAC to help inform the decision-making process.  OBJECTIVES: To assess the effect of lens extraction compared to LPI in the treatment of APAC.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2022, Issue 1), Ovid MEDLINE, Ovid MEDLINE E-pub Ahead of Print, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily (January 1946 to 10 January 2022), Embase (January 1947 to 10 January 2022), PubMed (1946 to 10 January 2022), Latin American and Caribbean Health Sciences Literature Database (LILACS) (1982 to 10 January 2022), ClinicalTrials.gov, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not use any date or language restrictions in the electronic search. We last searched the electronic databases on 10 January 2022.

SELECTION CRITERIA

We included randomized controlled clinical trials comparing lens extraction against LPI in adult participants ( ≥ 35 years) with APAC in one or both eyes.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology and assessed the certainty of the body of evidence for prespecified outcomes using the GRADE approach.

MAIN RESULTS

We included two studies conducted in Hong Kong and Singapore, comprising 99 eyes (99 participants) of predominantly Chinese origin. The two studies compared LPI with phacoemulsification performed by experienced surgeons. We assessed that both studies were at high risk of bias. There were no studies evaluating other types of lens extraction procedures.  Phacoemulsification may result in an increased proportion of participants with intraocular pressure (IOP) control compared with LPI at 18 to 24 months (risk ratio (RR) 1.66, 95% confidence interval (CI) 1.28 to 2.15; 2 studies, n = 97; low certainty evidence) and may reduce the need for further IOP-lowering surgery within 24 months (RR 0.07, 96% CI 0.01 to 0.51; 2 studies, n = 99; very low certainty evidence). Phacoemulsification may result in a lower mean IOP at 12 months compared to LPI (mean difference (MD) -3.20, 95% CI -4.79 to -1.61; 1 study, n = 62; low certainty evidence) and a slightly lower mean number of IOP-lowering medications at 18 months (MD -0.87, 95% CI -1.28 to -0.46; 1 study, n = 60; low certainty evidence), but this may not be clinically significant. Phacoemulsification may have little to no effect on the proportion of participants with one or more recurrent APAC episodes in the same eye (RR 0.32, 95% CI 0.01 to 7.30; 1 study, n = 37; very low certainty evidence). Phacoemulsification may result in a wider iridocorneal angle assessed by Shaffer grading at six months (MD 1.15, 95% CI 0.83 to 1.47; 1 study, n = 62; very low certainty evidence). Phacoemulsification may have little to no effect on logMAR best-corrected visual acuity (BCVA) at six months (MD -0.09, 95% CI -0.20 to 0.02; 2 studies, n = 94; very low certainty evidence). There was no evidence of a difference in the extent of peripheral anterior synechiae (PAS) (clock hours) between intervention arms at 6 months (MD -1.86, 95% CI -7.03 to 3.32; 2 studies, n = 94; very low certainty evidence), although the phacoemulsification group may have less PAS (degrees) at 12 months (MD -94.20, 95% CI -140.37 to -48.03; 1 study, n = 62) and 18 months (MD -127.30, 95% CI -168.91 to -85.69; 1 study, n = 60).  In one study, there were 26 adverse events in the phacoemulsification group: intraoperative corneal edema (n = 12), posterior capsular rupture (n = 1), intraoperative bleeding from iris root (n = 1), postoperative fibrinous anterior chamber reaction (n = 7), and visually significant posterior capsular opacification (n = 5), and no cases of suprachoroidal hemorrhage or endophthalmitis. There were four adverse events in the LPI group: closed iridotomy (n = 1) and small iridotomies that required supplementary laser (n = 3). In the other study, there was one adverse event in the phacoemulsification group (IOP > 30 mmHg on day 1 postoperatively (n = 1)), and no intraoperative complications. There were five adverse events in the LPI group: transient hemorrhage (n = 1), corneal burn (n = 1), and repeated LPI because of non-patency (n = 3).  Neither study reported health- or vision-related quality of life measures.

AUTHORS' CONCLUSIONS

Low certainty evidence suggests that early lens extraction may produce more favorable outcomes compared to initial LPI in terms of IOP control. Evidence for other outcomes is less clear. Future high-quality and longer-term studies evaluating the effects of either intervention on the development of glaucomatous damage and visual field changes as well as health-related quality of life measures would be helpful.

Clinical implication of recent randomized control trial in primary angle-closure disease management

Blindness due to primary angle-closure glaucoma (PACG) can be reduced significantly if the ongoing angle-closure process is arrested at an early stage. Various treatments such as laser peripheral iridotomy (LPI), iridoplasty, and clear lens extraction (CLE) have been advocated as first-line therapy for primary angle-closure (PAC), PACG, and high-risk cases of primary angle-closure suspect (PACS). EAGLE study, propagated the effectiveness of CLE over LPI for the management of primary angle closure and have sparked controversy regarding the role of LPI as a first line procedure. Randomized controlled trials (RCT), systematic reviews, and meta-analyses of RCTs done on the same question provide us with a solid base for creating guidelines/modules for our day-to-day clinical practice. A systematic review was conducted, searching several databases, including PubMed, Cochrane Library, EMBASE, and ClinicalTrials.gov, for the last 16 years (January 2005–December 2021) for RCTs with data published related to primary angle-closure disease (PACD). The search strategy included the following terms: “Primary Angle Closure disease,” “Primary Angle Closure Glaucoma,” “Primary Angle Closure,” “Primary Angle Closure Suspect,” “clear lens extraction,” “laser iridotomy,” “laser peripheral iridotomy,” “argon laser peripheral iridoplasty,” “selective laser trabeculoplasty,” “trabeculectomy,” “randomized control trial,” and “meta-analysis of randomized control trial.” In this review, we will discuss recently published RCTs (within the last 16 years) for the management of PACD and their clinical implications in day-to-day practice.

Comparison of Laser Iridotomy and Lensectomy Outcomes for Acute Primary Angle Closure

Purpose

To compare the clinical outcomes of the different treatments for acute primary angle closure (APAC).

Methods

We retrospectively reviewed the clinical charts of 87 eyes of 87 patients undergoing treatment for APAC. We investigated the best spectacle-corrected visual acuity (BSCVA), intraocular pressure (IOP), corneal endothelial cell density (ECD), and secondary interventions after each treatment.

Results

The pretreated IOP was 56.4 ± 9.0 mmHg. As the first treatment for APAC, all eyes underwent topical 2% pilocarpine and systemic mannitol administration. Subsequent laser iridotomy (LI) and lensectomy were necessary in 29 eyes (33%) and 35 eyes (40%), respectively. Bullous keratopathy developed in 1 eye (1%), and following glaucoma surgery was required in 7 eyes (8%). The BSCVA at the final follow-up was 0.16 ± 0.53 and 0.01 ± 0.20 logMAR (Mann–Whitney U test, p=0.149), the IOP was 12.8 ± 2.6, and 12.6 ± 2.9 mmHg (p=0.860), and the ECD was 2295.9 ± 658.2 and 2244.1 ± 622.0 cells/mm² (p=0.735) in the LI and lensectomy groups, respectively.

Conclusions

Approximately 26% of eyes with APAC were resolved after the initial medical treatment, and subsequent surgical treatments, such as LI and lensectomy, were required in 33% and 40% of eyes, respectively. We found no significant differences in the BSCVA, the IOP, or the ECD among LI and lensectomy treatment groups.

Association Between Anterior Chamber Angle and Corneal Endothelial Cell Density in Chronic Angle Closure

Purpose

To study the association between corneal endothelial cell density (ECD) and degree of anterior chamber angle (ACA) opening in eyes with chronic angle closure glaucoma.

Methods

The study was conducted at JEC Eye Hospitals in Indonesia. Treatment-naïve patients aged ≥40 years with IOP >21 mmHg and peripheral anterior chamber depth (ACD) grade 2 or less by Van Herick's technique were recruited. Trabecular iris angle (TIA; degree) was measured using anterior segment optical coherence tomography (AS-OCT) and classified as: grade 1 ≤10°, grade 2 11-20°, and grade 3 >20°. Noncontact specular microscopy was performed, and the following corneal parameters were obtained:ECD (cells/mm²), coefficient of variation (CV; μm²/cell), percentage of hexagonal cells, and central corneal thickness (CCT; μm).

Results

A total of 52 eyes from 52 subjects were recruited (16 grade 1 TIA, 24 grade 2 TIA, and 12 grade 3 TIA). Presenting IOP was not significantly different between groups. The median central corneal ECD was 2684.5 (1433-2934), 2587.0 (1902-3103), and 2441.0 (1659-3005) cells/mm² in grade 1, 2, and 3 TIA, respectively, with no significant differences across the groups (P = 0.67). The CV was lowest in grade 3 TIA (36.4 ± 7.2 μm2/cell), and highest in grade 1 TIA (38.3 ± 9.6 μm2/cell), but the differences were not significant (P = 0.74). Likewise, the percentage of hexagonality and CCT was not significantly different. TIA was not correlated with IOP but was modestly correlated with age.

Conclusion

The corneal ECD and morphological characteristics such as CV and hexagonality were not significantly different across various TIA grading in chronic angle closure. This may reflect the lack of chronic and gradual IOP insult on corneal endothelial parameters as TIA did not show direct effect towards IOP.

Factors affecting the corneal endothelium after selective laser trabeculoplasty in primary open angle and angle closure glaucoma

Purpose

To study the factors affecting the corneal endothelium after selective laser trabeculoplasty (SLT) in primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG).

Method

This prospective interventional study included 56 patients (56 eyes) with POAG and 55 patients (55 eyes) with PACG. All participants received a standard SLT session. Patients with PACG were pretreated with laser peripheral iridotomy for at least 2 months before SLT. Corneal endothelium cell count (ECC), pleomorphism and polymegathism were measured before SLT, as well as at the increments of 1 hour, 1 day, 1 week, 1 month, 3 months and 6 months following SLT using confocal microscopy. A multiple regression analysis was applied to detect the factors affecting the ECC in the long-term post-SLT period.

Results

In both groups, the mean ECC significantly decreased from the baseline after SLT. While in POAG, corneal endothelium recovered within 1 month, in PACG, its damage persisted throughout the whole follow-up period.

According to the multiple analysis, baseline ECC (β=0.891, p=0.000 in POAG and β=0.706, p=0.000 in PACG) and age (β=−0.227, p=0.000 in POAG and β=−0.196, p=0.000 in PACG) were the common risk factors affecting ECC in both glaucoma forms, while the initial anterior chamber depth (β=0.254, p=0.000), only in PACG. The duration of glaucoma treatment (β=−0.317, p=0.043 in POAG and β=−0.302, p=0.047 in PACG) and pigmented deposits on the corneal endothelium in PACG (β=−0.326, p=0.019) were the risk factors determined in the univariate analysis.

Conclusion

Age and the baseline ECC are the risk factors for corneal endothelium damage after SLT in POAG and PACG. Shallow anterior chamber may affect corneal endothelium in PACG. These data should be considered when choosing an algorithm for glaucoma treatment.

Iridocorneal contact as a potential cause of corneal decompensation following laser peripheral iridotomy

PURPOSE

This study aimed to investigate the relationship between corneal decompensation following laser peripheral iridotomy (LPI) and iridocorneal endothelial contact.

STUDY DESIGN

Retrospective observational case series.

METHODS

Specular microscopy images of LPI recipients with narrow angles were taken at the central cornea and the 8 midperipheral corneal regions at approximately 3 mm from the center. Eleven eyes of 11 patients had a minimum of  ≤ 1600 cells/mm² among 8 midperipheral corneal endothelial cell densities (ECDs). Radial scans of the angles in the 8 directions were taken with ultrasound biomicroscopy (UBM) in the supine and face-down positions. The minimum and maximum angle opening distance at 750 μm from the scleral spur of the 8 directions were defined as the narrowest and widest angles, respectively. The ECD of the narrowest angle direction was compared with the ECD of the widest angle direction.

RESULTS

When UBM was performed with the subject in the supine position, the iris and cornea at the narrowest angle were in contact in only 4 of 11 eyes, while in the face-down position, the iris and the cornea at the narrowest angle were in contact in 10 of the 11 eyes. In the face-down UBM, the midperipheral ECD of the narrowest angle direction was significantly smaller than the midperipheral ECD of the widest angle direction (P = 0.006).

CONCLUSION

The ECD of the narrow angle direction can decrease after LPI. This suggests that corneal endothelial cell damage following LPI may be due to mechanical damage from iridocorneal endothelial contact.

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

A healthy corneal endothelium is required for corneal clarity. Both the glaucoma disease state and its various forms of treatment can have adverse effects on the corneal endothelium. Both the presence of glaucoma and the magnitude of intraocular pressure elevation are related to endothelial cell loss (ECL). Topical medical therapy, laser procedures, and both traditional surgeries-trabeculectomy and tube-shunts-and newer minimally invasive glaucoma surgeries have variable effects on ECL. This review will summarize the reported effects of glaucoma and its treatment on ECL. Concerns for corneal endothelial cell health should be part of the decision-making process when planning glaucoma therapy for lowering intraocular pressure, with added caution in case of planned device implantation in eyes with preexisting ECL and low endothelial cell density at high risk for corneal endothelial decompensation.

Corneal endothelial dysfunction: Evolving understanding and treatment options

The cornea is exquisitely designed to protect the eye while transmitting and focusing incoming light. Precise control of corneal hydration by the endothelial cell layer that lines the inner surface of the cornea is required for optimal transparency, and endothelial dysfunction or damage can result in corneal edema and visual impairment. Advances in corneal transplantation now allow selective replacement of dysfunctional corneal endothelium, providing rapid visual rehabilitation. A series of technique improvements have minimized complications and various adaptations allow use even in eyes with complicated anatomy. While selective endothelial keratoplasty sets a very high standard for safety and efficacy, a shortage of donor corneas in many parts of the world restricts access, prompting a search for alternatives. Clinical trials are underway to evaluate the potential for self-recovery after removal of dysfunctional central endothelium in patients with healthy peripheral endothelium. Various approaches to using cultured human corneal endothelial cells are also in clinical trials; these aim to multiply cells from a single donor cornea for use in potentially hundreds of patients. Pre-clinical studies are underway with induced pluripotent stem cells, endothelial stem cell regeneration, gene therapy, anti-sense oligonucleotides, and various biologic/pharmacologic approaches designed to treat, prevent, or retard corneal endothelial dysfunction. The availability of more therapeutic options will hopefully expand access around the world while also allowing treatment to be more precisely tailored to each individual patient.

Predictors of Endothelial Cell Loss after Phacoemulsification for the Treatment of Primary Angle Closure

Purpose

To investigate demographic and anatomical factors associated with a reduction in endothelial cell density (ECD) after phacoemulsification (PE) for the treatment of primary angle closure (PAC).

Methods

In this prospective case series, ECD was evaluated by noncontact specular microscopy and biometric parameters by both noncontact optical biometry and anterior segment optical coherence tomography, preoperatively and at 12 months after surgery. Anterior segment biomicroscopy and gonioscopy were also performed. The change in ECD and its relation to clinical characteristics and biometric parameters were evaluated by linear regression analysis.

Results

44 patients with PAC were included in the study. The mean (SD) patient age was 71.6 (10.2) years; thirty-one (70.5%) of them were women. Coexistence of exfoliation syndrome (XS) was observed in 4 cases (9.1%). The mean (SD) ECD (cells/mm²) changed from 2275 (463) preoperatively to 1964 (613) postoperatively with a mean reduction of −310 (95% CI −445 to −176; p < 0.001). In the multivariate regression model, after correction for age and lens status, XS was the only parameter associated with ECD percentage change (B = −36.00; p=0.001).

Conclusion

PE in angle closure causes a significant ECD reduction. In our population of PAC patients, XS is significantly associated with ECD change. In this group of patients, a careful preoperative endothelial evaluation should be performed.

Long-Term Evaluation of Specular Microscopic Changes Following Nd: YAG Iridotomy in Chronic Primary Angle-Closure Glaucoma Eyes

AIM

The aim of this study was to evaluate specular microscopy of chronic primary angle-closure glaucoma (CPACG) eyes at least 1 year after Nd:YAG iridotomy, and compare them with CPACG eyes without an iridotomy and age-matched, normal eyes.

PATIENTS AND METHOD

Consecutive patients of CPACG at the Glaucoma service were screened. All patients underwent slit-lamp biomicroscopy, +90 D examination, and applanation tonometry. A total of 100 eyes of 100 consecutive patients of CPACG with an Nd:YAG iridotomy performed ≥1 year before, who met all inclusion/exclusion criteria, 60 consecutive CPACG eyes without an iridotomy, and 60 age and refraction-matched control eyes were enrolled. A specular microscopy was performed in one eye of each patient by an observer masked to diagnosis.

RESULTS

CPACG patients had a mean age of 62±8 years, a mean intraocular pressure of 18±5.3 mm Hg, a mean specular count of 2536±224 cells/mm, and mean duration after iridotomy of 3.2±2 years. There was a significant correlation of specular endothelial counts with age (r=-0.39; P<0.001) and interval after iridotomy (r=-0.25; P=0.01). CPACG eyes without an iridotomy had a mean age of 62±5 years and a mean specular count of 2469±199 cells/mm. Normal control eyes with a mean age of 61±6 years had a mean specular count of 2729±299 cells/mm. There was no significant difference in specular count between CPACG eyes with or without an iridotomy (P=0.19); however, both CPACG groups had a specular count significantly lower than controls (P=0.01 and 0.02, respectively). There was no statistically significant difference seen in polymegathism (coefficient of variation) and pleomorphism (% of hexagonal cells) in endothelial cells among the 3 groups.

CONCLUSIONS

An Nd:YAG iridotomy in CPACG eyes did not lead to any significant changes in central corneal specular microscopy in the long term as compared with patients who did not undergo iridotomy. Eyes with CPACG, without and after an iridotomy, had a lower specular count compared with age-matched controls.

Comparison of laser iridotomy using short duration 532-nm Nd: YAG laser (PASCAL) vs conventional laser in dark irides

AIM

To evaluate the outcome of laser iridotomy using 532-nm Nd: YAG laser (PASCAL) with short pulse duration and Nd: YAG laser compared to conventional combined laser iridotomy.

METHODS

Retrospective, nonrandomized, comparative case series. Forty-five eyes of 34 patients underwent laser iridotomy. Twenty-two eyes underwent iridotomy using short duration PASCAL and Nd: YAG laser, and 23 eyes underwent iridotomy using conventional combined laser method. The average settings of PASCAL were 60 µm and 700-900 mW with a short duration of 0.01s to reduce the total applied energy. The conventional laser was 50 µm and 700-900 mW for 0.1s. After photocoagulation with these laser, the Nd: YAG laser was added in each group. Endothelial cell counts of pre-iridotomy and 2mo after iridotomy were measured and compared.

RESULTS

All eyes completed iridotomy successfully. The total energy used in the PASCAL group was 1.85±1.17 J. Compared to conventional laser 13.25±1.67 J, the energy used was very small due to the short exposure time of PASCAL. Endothelial cell counts were reduced by 0.88% in the PASCAL group and 6.72% in the conventional laser group (P=0.044). The change in corneal endothelial cell counts before and after iridotomy was significant in conventional combined laser iridotomy group (P=0.004).

CONCLUSION

Combined PASCAL and Nd:YAG laser iridotomy is an effective and safe technique in the dark brown irides of Asians. Furthermore, the short duration of exposure in PASCAL offers the advantages of reducing the total energy used and minimizing the corneal damage.

Evaluation of the toric implantable collamer lens for simultaneous treatment of myopia and astigmatism

Myopic astigmatism is a prevalent condition that can be treated with spectacles, contact lenses, or laser refractive surgery. However, these treatment options have functional limitations at higher levels of refractive error. The toric implantable collamer lens is designed to treat a broad range of refractive error, generally up to -18 diopters with +1 to +6 diopters of astigmatism. Approval for a more limited treatment range of up to 15 diopters of myopia with +1 to +4 diopters of astigmatism is being sought in the US, where this device has not yet received marketing approval. Surgical correction of high-myopic astigmatism can be life-altering and allow people to participate in activities that were not previously feasible because of visual limitations. The toric implantable collamer lens is implanted behind the iris and in front of the natural crystalline lens. With earlier lens designs, it was necessary to create an iridectomy or iridotomy to prevent pupillary block. The newest toric implantable collamer lens model has a small central hole that is not visually noticeable. This eliminates the need to create a hole in the iris, thereby enhancing the safety of the procedure.

Laser iridotomy and the corneal endothelium: a systemic review

This study aims to systemically review the effect of laser iridotomy on the corneal endothelium. Searches were performed for studies that either compared corneal endothelial cell density/count, corneal thickness and morphology pre- and postiridotomy, or evaluated the postiridotomy development of corneal decompensation. There were 26 eligible studies. Our review shows that the effect of laser iridotomy on the corneal endothelium has been investigated with varying results. Although it has been demonstrated to be a relatively safe procedure, there is still the potential long-term risk of corneal decompensation, for which a corneal transplantation may be indicated eventually. The longest interval between laser iridotomy and corneal decompensation reported was 8 years. Mechanisms proposed for endothelial damage include direct focal injury, thermal damage, mechanical shock waves, iris pigment dispersion, transient rise in intraocular pressure, inflammation, turbulent aqueous flow, time-dependent shear stress on endothelium, chronic breakdown of blood-aqueous barrier and damage from bubbles that settled onto the endothelium. Inherent risk factors identified were iridotrabecular contact, current or prior acute angle closure, pigmented irides, small iris-to-endothelium distance, pre-existing endothelial disease and diabetes. Intervention-related risk factors include laser type, delivery and quantity. The significance of the risk factors and their direct association with the development of corneal decompensation remain to be determined. Understanding these risk factors may allow physicians to counsel their patients better. They may offer opportunities for preventive strategies, allowing us to ensure that a procedure performed to prevent disease progression and visual loss does not cause further morbidity.