Increased mast cell numbers in the conjunctiva of glaucoma patients: a possible indicator of preoperative glaucoma surgery inflammation

Implantation of XEN gel stent in a patient with ocular cicatricial pemphigoid

Purpose

Herein, we report a case of XEN gel stent implantation in a patient with ocular cicatricial pemphigoid that successfully reduced glaucoma topical medication at one year.

Observations

A 76-year-old male patient presented with severe ocular cicatricial pemphigoid and advanced glaucoma who required several topical medications to control intraocular pressure. Despite successful reduction of ocular inflammation with immunomodulatory therapy, his topical medication regimen prevented total remission of ocular inflammation. One year after XEN gel stent implantation, his intraocular pressures were controlled without any topical medication, and he had no ocular inflammation off any immunomodulatory therapy.

Conclusions and Importance

The XEN gel stent represents a useful intervention for glaucoma treatment even in the setting of severe ocular surface disease and can improve outcomes for concurrent inflammatory and glaucomatous pathology.

Promotion of conjunctival fibroblast-mediated collagen gel contraction by mast cells through up-regulation of matrix metalloproteinase release and activation

Mast cells and conjunctival fibroblasts contribute to conjunctival wound healing and allergic ocular inflammation. The number of mast cells in the conjunctiva is increased in individuals with cicatricial fibrosis-causing ocular surface diseases and after glaucoma filtering surgery, suggesting that these cells may contribute to the scarring observed after such surgery. We studied the potential mechanism of fibroblast-mast cell interaction in the healing of conjunctival wounds using a three-dimensional collagen gel culture system. We found that mast cells derived from the bone marrow of mice embedded in a collagen gel did not induce gel contraction. However, an increase in mast cells was associated with increased collagen gel contraction mediated by mouse conjunctival fibroblasts. The extent of collagen degradation was not affected by the co-culture of mast cells and conjunctival fibroblasts. Gelatin zymography disclosed that mast cells increased the amounts of both the pro form of matrix metalloproteinase (MMP)-9 and the active form of MMP-2 in supernatants of conjunctival fibroblast cultures. Furthermore, the potentiating effect of mast cells on contraction of the collagen gel through conjunctival fibroblasts was attenuated by the addition of a synthetic MMP inhibitor. Thus, current results suggest that mast cells accelerate the conjunctival fibroblast-dependent contraction of collagen gel by increasing the release as well as activation of MMPs. Therefore, the interaction between mast cells and conjunctival fibroblasts may contribute to conjunctival scar formation after glaucoma filtering surgery.

Looking into the future: Gene and cell therapies for glaucoma

Glaucoma is a complex group of optic neuropathies that affects both humans and animals. Intraocular pressure (IOP) elevation is a major risk factor that results in the loss of retinal ganglion cells (RGCs) and their axons. Currently, lowering IOP by medical and surgical methods is the only approved treatment for primary glaucoma, but there is no cure, and vision loss often progresses despite therapy. Recent technologic advances provide us with a better understanding of disease mechanisms and risk factors; this will permit earlier diagnosis of glaucoma and initiation of therapy sooner and more effectively. Gene and cell therapies are well suited to target these mechanisms specifically with the potential to achieve a lasting therapeutic effect. Much progress has been made in laboratory settings to develop these novel therapies for the eye. Gene and cell therapies have already been translated into clinical application for some inherited retinal dystrophies and age-related macular degeneration (AMD). Except for the intravitreal application of ciliary neurotrophic factor (CNTF) by encapsulated cell technology for RGC neuroprotection, there has been no other clinical translation of gene and cell therapies for glaucoma so far. Possible application of gene and cell therapies consists of long-term IOP control via increased aqueous humor drainage, including inhibition of fibrosis following filtration surgery, RGC neuroprotection and neuroregeneration, modification of ocular biomechanics for improved IOP tolerance, and inhibition of inflammation and neovascularization to prevent the development of some forms of secondary glaucoma.

[Preoperative management of subconjunctival/sub-Tenon's glaucoma surgery with special consideration of the gel implant (XEN®)]

BACKGROUND

When using subconjunctival/sub-Tenon's ab interno glaucoma surgical procedures, patient selection and preoperative management are essential to reduce postoperative scarring of the bleb.

OBJECTIVE

The aim of this study was to compile a list of risk factors that may have an unfavorable effect on the scarring process.

METHOD

A literature search was carried out in PubMed with respect to the scarring process of the gel implant XEN®.

RESULTS

Ophthalmological risk factors for conjunctivoscleral/Tenon's wound healing process include dry eye, allergies, use of eye drops containing preservatives and previous eye surgery.

CONCLUSION

The preoperative administration of artificial tear substitutes, corticosteroids and the fundamental change to preservative-free eye drops can support the normalization of a chronic inflammatory altered conjunctiva and thus positively influence the wound healing process after surgery.

Experimental models of glaucoma filtration surgery

Glaucoma filtration surgery plays an important role in achieving intraocular pressure (IOP) reduction in patients who have high IOP despite maximum medical therapy. Preclinical experimental models of glaucoma filtration surgery contribute a great deal to our knowledge of the wound healing processes that predispose to scarring and may lead to poor outcomes. However, this research needs to be interpreted in the light of the specific study design, animal model and methods used. We review the existing literature addressing various models of experimental glaucoma filtration surgery, discuss the considerations in assessing these models and describe future steps in evaluating potential therapeutics and bleb characteristics that could impact translational research in this field.

Absence of lymphatic vessels in non-functioning bleb capsules of glaucoma drainage devices

PURPOSE

To evaluate the presence and appearance of blood and lymphatic vessels in non-functioning bleb capsules of glaucoma drainage devices (GDD).

MATERIALS AND METHODS

Non-functioning (n=14) GDD-bleb capsules of 12 patients were analyzed by immunohistochemistry for blood vessels (CD31, vascular endothelium), lymphatic vessels (lymphatic vessel endothelial hyaluronan receptor-1 [LYVE-1] and podoplanin) and macrophages (CD68).

RESULTS

CD31+++ blood vessels and CD68+ macrophages were detected in the outer layer of all specimens. LYVE-1 immunoreactivity was registered in single non-endothelial cells in 8 out of 14 (57%) bleb capsule specimens. Podoplanin-immunoreactivity was detected in all cases, located in cells and profiles of the collagen tissue network of the outer and/or the inner capsule layer. However, a colocalization of LYVE-1 and podoplanin as evidence for lymphatic vessels was not detected.

CONCLUSIONS

We demonstrate the presence of blood-vessels but absence of lymphatic vessels in non-functioning bleb capsules after GDD-implantation. While the absence of lymphatic vessels might indicate a possible reason for drainage device failure, this needs to be confirmed in upcoming studies, including animal experiments.

Stab incision mitomycin C-assisted rapid trabeculectomy: A 'SMART' trabeculectomy alternative

The aim of the present study was to introduce a new modified trabeculectomy technique, stab incision mitomycin C (MMC)-assisted rapid trabeculectomy (SMART), which requires less surgical time and tissue manipulation. A total of 41 eyes with indication for trabeculectomy underwent glaucoma surgery with the SMART technique; superior subconjunctival injection of 0.005 mg MMC mixed with 0.1 ml lidocaine, followed by small, fornix base conjunctival opening. A stab incision was made to enter the anterior chamber 1.5 mm post-limbus using a 2.4 mm cataract knife. Double 0.75 mm punch and peripheral iridectomy were performed. A releasable suture was placed in the scleral opening, and matrix sutures to close conjunctiva. The preoperative mean intraocular pressure (IOP) was 23.8 mmHg, with a mean number of medications of 3.3. The mean follow-up duration was 27.6 months, with a range of 12-46 months. A year post-surgery, the mean IOP was 11 mmHg, with a mean number of medications of 0.7, corresponding to a reduction of 12.8 mmHg in IOP and 2.6 in the number of medications. During follow-up, additional 5-fluorouracil injections were administered when needed. In conclusion, SMART with wound modulation appears to be a safe and quick alternative to classic trabeculectomy. Few minor and no major complications were observed during the first 2.5 years of follow-up, with all eyes maintaining an IOP <15 mmHg.

Endogenous Annexin-A1 Negatively Regulates Mast Cell-Mediated Allergic Reactions

Mast cell stabilizers like cromoglycate and nedocromil are mainstream treatments for ocular allergy. Biochemical studies in vitro suggest that these drugs prevent mast cell degranulation through the release of Annexin-A1 (Anx-A1) protein. However, the direct effect of Anx-A1 gene deletion on mast cell function in vitro and in vivo is yet to be fully investigated. Hence, we aim to elucidate the role of Anx-A1 in mast cell function, both in vivo and in vitro, using a transgenic mouse model where the Anx-A1 gene has been deleted. Bone marrow-derived mast cells (BMDMCs) were cultured from wild-type animals and compared throughout their development to BMDMCs obtained from mice lacking the Anx-A1 gene. The mast cell differentiation, maturity, mediator, and cytokine release were explored using multiple biochemical techniques, such as Western blots, ELISA, and flow cytometry analysis. Electron microscopy was used to identify metachromatic granules content of cells. For in vivo studies, Balb/C wild-type and Anx-A1-deficient mice were divided into the following groups: group 1, a control receiving only saline, and group 2, which had been sensitized by prior exposure to short ragweed (SRW) pollen by topical contact with the conjunctival mucosae. Allergic conjunctivitis was evaluated blind after 24 h by trained observers scoring clinical signs. Electron micrographs of BMDMCs from Anx-A1-null mice revealed more vacuoles overall and more fused vacuoles than wild-type cells, suggesting enhanced secretory activity. Congruent with these observations, BMDMCs lacking the Anx-A1 gene released significantly increased amounts of histamine both spontaneously as well as in response to Ig-E-FcεRI cross-linking compared to those from wild-type mice. Interestingly, the spontaneous release of IL-5, IL-6, IL-9, and monocyte chemoattractant protein-1 (MCP-1) were also markedly increased with a greater production observed upon IgE cross-linking. This latter finding is congruent with augmented calcium mobilization in BMDMCs lacking the Anx-A1 gene. In vivo, when compared to wild-type animals, Anx-A1-deficient mice exposed to SRW pollen displayed exacerbated signs and symptoms of allergic conjunctivitis. Taken together, these results suggest Anx-A1 is an important non-redundant regulator of mast cell reactivity and particularly in allergen mediated allergic reactions.

Long-term Follow-up of Ahmed Glaucoma Valve Tube Position Changes

PURPOSE

To evaluate long-term (4.5 to 6 y) changes in the position of Ahmed glaucoma valve (AGV) tubes.

MATERIALS AND METHODS

Adult patients aged 18 years and above, 1 to 2 months post-AGV implantation were enrolled. Tube position was evaluated using anterior segment optical coherence tomography at baseline and final follow-up. The intracameral tube length (ICL), tube-cornea (TC) distance, and cornea-tube angle were measured. Wilcoxon-signed rank test was used to assess whether the changes in parameters from baseline were significant.

RESULTS

In total, 11 eyes of 9 patients were included in the analysis. Mean duration of follow-up was 5.2±0.8 years (4.4 to 6.1 y). The ICL increased from 1.58±0.40 to 1.74±0.62 mm (P=0.18). The TC decreased from 0.36±0.12 to 0.29±0.05 mm (P=0.04). The cornea-tube angle decreased from 27.76±5.57 to 24.82±5.69 degrees (P=0.08). Overall, 73% of the tubes moved toward the cornea (mean 0.11 mm, over 4.4 to 6.1 y). In total, 73% showed an increase in ICL; 45% showed an increase of >0.3 mm [mean 0.50 mm (33%) increase]. Two of 11 tubes (18%) showed no significant change in the parameters (ICL, 0.03 and 0.01 mm increase; TC, 0 and 0.01 mm increase); these tubes were noted to lie on the iris.

CONCLUSIONS

Tubes tend to move toward the cornea over time. To avoid corneal damage and involvement of the visual axis in the future, tubes should be reasonably short and inserted tangentially, preferably in the posterior one third of the anterior chamber.

Puerarin regulates neovascular glaucoma through pigment epithelium‑derived growth factor‑induced NF‑κB signaling pathway

Neovascular glaucoma is an ophthalmic disease and a potentially blinding secondary glaucoma caused by the formation of abnormal new blood vessels on the iris, which can prevent the normal drainage of water from the anterior segment of the eye. Evidence from China has suggested that puerarin benefits many diseases including myocardial infarction, stable angina, cerebral ischemia and glaucoma in a clinical setting. In the present study, the aim was to investigate the efficacies of puerarin on neovascular glaucoma in a mouse model. The molecular mechanism of puerarin‑mediated treatment for neovascular glaucoma was also investigated both in vitro and in vivo. Inflammatory responses in mice with neovascular glaucoma were analyzed by western blotting. Oxidative stress levels were investigated following treatment with puerarin in a mouse model of neovascular glaucoma. The results indicated that puerarin markedly improved growth of vascular endothelial cells. The present study reported that puerarin treatment markedly decreased interleukin (IL)‑1β, IL‑17A and tumor necrosis factor‑α expression levels in mice with neovascular glaucoma. It was found that puerarin significantly decreased oxidative stress levels by reducing reactive oxygen species, superoxide dismutase and malondialdehyde levels, as well as neuronal nitric oxide synthase (NOS) and inducible NOS expression levels. Results indicated that expression levels of pigment epithelium‑derived growth factor were significantly inhibited following treatment with puerarin. Mechanism analysis demonstrated that treatment with puerarin effectively inhibited nuclear factor (NF)‑κB activity and its target protein levels p65, inhibitor of NF‑κB kinase subunit β and inhibitor of NF‑κB kinase subunit α in vascular endothelial cells. Increasing endothelial‑derived growth factor (EDGF) expression levels could stimulate NF‑κB activity and abolish the inhibitory effects of puerarin. An animal study reported that puerarin treatment presented therapeutic effects for mice with neovascular glaucoma. Numbers of new vessels in iris were recovered to normal following puerarin treatment. In conclusion, these results indicated that puerarin treatment can inhibit inflammatory responses and oxidative stress, platelet‑derived growth factor (PDGF) expression and NF‑κB activity, suggesting puerarin may be a potential agent for the treatment of neovascular glaucoma through PDGF‑induced NF‑κB signaling pathway.

Oral Ultramicronized Palmitoylethanolamide: Plasma and Tissue Levels and Spinal Anti-hyperalgesic Effect

Palmitoylethanolamide (PEA) is a pleiotropic lipid mediator with established anti-inflammatory and anti-hyperalgesic activity. Ultramicronized PEA (PEA-um) has superior oral efficacy compared to naïve (non-micronized) PEA. The aim of the present study was two-fold: (1) to evaluate whether oral PEA-um has greater absorbability compared to naïve PEA, and its ability to reach peripheral and central tissues under healthy and local inflammatory conditions (carrageenan paw edema); (2) to better characterize the molecular pathways involved in PEA-um action, particularly at the spinal level. Rats were dosed with 30 mg/kg of [¹³C]₄-PEA-um or naïve [¹³C]₄-PEA by oral gavage, and [¹³C]₄-PEA levels quantified, as a function of time, by liquid chromatography/atmospheric pressure chemical ionization/mass spectrometry. Overall plasma levels were higher in both healthy and carrageenan-injected rats administered [¹³C]₄-PEA-um as compared to those receiving naïve [¹³C]₄-PEA, indicating the greater absorbability of PEA-um. Furthermore, carrageenan injection markedly favored an increase in levels of [¹³C]₄-PEA in plasma, paw and spinal cord. Oral treatment of carrageenan-injected rats with PEA-um (10 mg/kg) confirmed beneficial peripheral effects on paw inflammation, thermal hyperalgesia and tissue damage. Notably, PEA-um down-regulated distinct spinal inflammatory and oxidative pathways. These last findings instruct on spinal mechanisms involved in the anti-hyperalgesic effect of PEA-um in inflammatory pain.

Genotype-Phenotype Associations of IL6 and PRG4 With Conjunctival Fibrosis After Glaucoma Surgery

Importance

Postsurgical fibrosis is a critical determinant of the long-term success of glaucoma surgery, but no reliable biomarkers are currently available to stratify the risk of scarring.

Objective

To compare the clinical phenotype of patients with conjunctival fibrosis after glaucoma surgery with candidate gene expression tissue biomarkers of fibrosis.

Design, Setting, and Participants

In this cross-sectional study, 42 patients were recruited at the time of glaucoma surgery at the Moorfields Eye Hospital from September 1, 2014, to September 1, 2016. The participants were divided into those with fibrosis and those without fibrosis.

Main Outcomes and Measures

Genotype-phenotype correlations of the IL6 or PRG4 gene and detailed clinical phenotype. The IL6 and PRG4 protein expression in conjunctival tissues was also assessed using in situ immunohistochemical analysis. Central bleb area, maximal bleb area, and bleb height were graded on a scale of 1 to 5 (1 indicating 0%; 2, 25%; 3, 50%; 4, 75%; and 5, 100%). Bleb vascularity was graded on a scale of 1 to 5 (1 indicating avascularity; 2, normal; 3, mild; 4, moderate; and 5, severe hyperemia).

Results

A total of 42 patients were recruited during the study period; 28 participants (67%) had previously undergone glaucoma surgery (fibrotic group) (mean [SD] age, 43.8 [3.6 years]; 16 [57%] female; 22 [79%] white), and 14 participants (33%) had not previously undergone glaucoma surgery (nonfibrotic group) (mean [SD] age, 47.7 [6.9] years; 4 [29%] female; 9 [64%] white). The fibrotic group had marked bleb scarring and vascularization and worse logMAR visual acuity. The mean (SD) grades were 1.4 (0.1) for central bleb area, 1.4 (0.1) for bleb height, and 3.4 (0.2) for bleb vascularity. The IL6 gene was upregulated in fibrotic cell lines (mean, 0.040) compared with nonfibrotic cell lines (mean, 0.011) (difference, 0.029; 95% CI, 0.015-0.043; P = .003). The PRG4 gene was also downregulated in fibrotic cell lines (0.002) compared with nonfibrotic cell lines (mean, 0.109; difference, 0.107; 95% CI, 0.104-0.110; P = .03). The study found a strong correlation between the IL6 gene and the number of glaucoma operations (r = 0.94, P < .001) and logMAR visual acuity (r = 0.64, P = .03). A moderate correlation was found between the PRG4 gene and the number of glaucoma operations (r = -0.72, P = .005) and logMAR visual acuity (r = -0.62, P = .03).

Conclusions and Relevance

IL6 and PRG4 represent potential novel tissue biomarkers of disease severity and prognosis in conjunctival fibrosis after glaucoma surgery. Future longitudinal studies with multiple postoperative measures are needed to validate the effect of these potential biomarkers of fibrosis.

Personalized Medicine in Ocular Fibrosis: Myth or Future Biomarkers

Significance: Fibrosis-related events play a part in the pathogenesis or failure of treatment of virtually all the blinding diseases around the world, and also account for over 40% of all deaths. It is well established that the eye and other tissues of some group of patients, for example Afro-Caribbean people, scar worse than others. However, there is a current lack of reliable biomarkers to stratify the risk of scarring and postsurgical fibrosis in the eye.

Recent Advances: Recent studies using genomics, proteomics, metabolomics, clinical phenotyping, and high-resolution in vivo imaging techniques have revealed potential novel biomarkers to identify and stratify patients at risk of scarring in different fibrotic eye diseases.

Critical Issues: Most of the studies, to date, have been done in animals or small cohorts of patients and future research is needed to validate these results in large longitudinal human studies. Detailed clinical phenotyping and effective biobanking of patient tissues will also be critical for future biomarker research in ocular fibrosis.

Future Directions: The ability to predict the risk of scarring and to tailor the antifibrotic treatment regimen to each individual patient will be an extremely useful tool clinically to prevent undertreating, or exposing patients to unnecessary treatments with potential side effects. An exciting future prospect will be to use new advances in genotyping, namely next-generation whole genome sequencing like RNA-Seq, to develop a customized gene chip in ocular fibrosis. Successful translation of future biomarkers to benefit patient care will also ultimately require a strong collaboration between academics, pharmaceutical, and biotech companies.

Stab Incision Glaucoma Surgery: A Modified Guarded Filtration Procedure for Primary Open Angle Glaucoma

Purpose. To describe a modified guarded filtration surgery, stab incision glaucoma surgery (SIGS), for primary open angle glaucoma (POAG). Methods. This prospective, interventional case series included patients with POAG (IOP ≥21 mmHg with glaucomatous visual field defects). After sliding superior conjunctiva down over limbus, 2.8 mm bevel-up keratome was used to create conjunctival entry and superficial corneoscleral tunnel in a single step starting 1.5 mm behind limbus. Lamellar corneoscleral tunnel was carefully dissected 0.5–1 mm into cornea and anterior chamber (AC) was entered. Kelly Descemet's punch (1 mm) was slid along the tunnel into AC to punch internal lip of the tunnel, thereby compromising it. Patency of ostium was assessed by injecting fluid in AC and visualizing leakage from tunnel. Conjunctival incision alone was sutured. Results. Mean preoperative IOP was 27.41 ± 5.54 mmHg and mean postoperative IOP was 16.47 ± 4.81 mmHg (n = 17). Mean reduction in IOP was 38.81 ± 16.55%. There was significant reduction of IOP (p < 0.000). 64.7% had IOP at final follow-up of <18 mmHg without medication and 82.35% had IOP <18 mmHg with ≤2 medications. No sight threatening complications were encountered. Conclusion. Satisfactory IOP control was noted after SIGS in interim follow-up (14.18 ± 1.88 months).

The Conjunctiva in Normal Tension Glaucoma Patients is Thinner Than in Primary Open-Angle Glaucoma Patients: A Comparative Histologic Study

PURPOSE

To compare histologically the thickness of conjunctival specimens of normal tension glaucoma (NTG) patients with primary open-angle glaucoma (POAG) patients.

MATERIALS AND METHODS

In this prospective study, 54 patients scheduled for trabeculectomy were categorized into NTG and POAG based on their maximum untreated intraocular pressure at any time (IOPmax) as measured by Goldmann applanation tonometry. Sixteen patients with NTG (IOPmax≤21 mm Hg) and 36 patients with high tension POAG (IOPmax>21 mm Hg) were included in the study. Biopsies were taken from the superior bulbar conjunctiva during trabeculectomy. The specimens were fixed in formalin, embedded in methacrylate, histologically sectioned, stained with toluidine blue, and analyzed with a light microscope. The stromal conjunctival thickness (CT) was measured in a standardized way and compared between the 2 groups. Intergroup comparisons were performed using the Mann-Whitney U test for continuous variables and the Fisher exact test for categorical variables. The correlation between the central cornea thickness (CCT) and the CT was investigated by the Spearman test.

RESULTS

The stromal CT was significantly thinner in NTG compared with POAG (64±31 vs. 103±44 µm, respectively; P=0.002). Stromal CT of the whole group was positively correlated with IOPmax (r=0.41; P=0.002; 95% confidence interval, 0.15-0.62) but not with central cornea thickness (r=-0.005; P=0.97; 95% confidence interval, -0.28 to 0.27).

CONCLUSIONS

The conjunctiva in patients with NTG was thinner than in POAG patients. This finding is an additional feature in the pattern of thinner ocular structures in patients with NTG.

Serial intracameral visualization of the Ahmed glaucoma valve tube by anterior segment optical coherence tomography

PURPOSE

To investigate serial changes of the Ahmed glaucoma valve (AGV) implant tube in the anterior chamber by anterior segment optical coherence tomography (AS-OCT).

METHODS

Patients who had received AGV implantation without complications (n=48) were included in this study. Each patient received follow-up examinations including AS-OCT at days 1 and 2, week 1, and months 1, 3, 6, and 12. Tube parameters were defined to measure its length and position. The intracameral length of the tube was from the tip of the bevel-edged tube to the sclerolimbal junction. The distance between the extremity of the tube and the anterior iris surface (T-I distance), and the angle between the tube and the posterior endothelial surface of the cornea (T-C angle) were defined. Factors that were related to tube parameters were analysed by multiple regression analysis.

RESULTS

The mean change in tube length was -0.20 ± 0.17 mm, indicating that the tube length shortened from the initial inserted length. The mean T-I distance change was 0.11 ± 0.07 mm and the mean T-C angle change was -6.7 ± 5.6°. Uveitic glaucoma and glaucoma following penetrating keratoplasty showed the most changes in tube parameters. By multiple regression analysis, diagnosis of glaucoma including uveitic glaucoma (P=0.049) and glaucoma following penetrating keratoplasty (P=0.008) were related to the change of intracameral tube length.

CONCLUSIONS

These results suggest that the length and position of the AGV tube changes after surgery. The change was prominent in uveitic glaucoma and glaucoma following penetrating keratoplasty.

Outcomes of trabeculectomy after descemet stripping automated endothelial keratoplasty: a comparison with penetrating keratoplasty

PURPOSE

To compare the outcomes of trabeculectomy surgery after Descemet stripping automated endothelial keratoplasty (DSAEK) to penetrating keratoplasty (PK).

DESIGN

Retrospective case-control study.

METHODS

Patients within an institutional setting who underwent trabeculectomy with mitomycin C (MMC) for uncontrolled elevated intraocular pressure (IOP) after corneal graft surgery were included. Patients with pre-existing glaucoma were excluded. Twenty patients with trabeculectomy after DSAEK and 41 patients with trabeculectomy after PK were analyzed. The main outcome measure was IOP control at 12 months. Secondary outcome measures were postoperative interventions including reinstatement of IOP-lowering medications, bleb needling with 5-fluorouracil (5FU) or further glaucoma surgery, and the incidence of complications related to trabeculectomy and/or corneal graft surgery.

RESULTS

There was no difference in pre-trabeculectomy IOP between DSAEK vs PK group (35.5 ± 10.1 vs 32.9 ± 8.9, P = .31). At 12 months after trabeculectomy, mean IOP in the DSAEK group was lower compared to the PK controls (10.6 ± 3.2 vs 14.6 ± 8.5, P = .04). The proportion of patients who achieved an IOP less than 12 mm Hg was significantly higher in the DSAEK group (80.0% vs 48.6%, P = .03). The proportions of eyes that required intervention after trabeculectomy were comparable between the 2 groups (DSAEK vs PK, all interventions: 20.0% vs 39.5%, P = .15; IOP-lowering medications required: 15.0% vs 39.5%, P = .08; needling with 5FU: 20.0% vs 23.7%, P > .99; further glaucoma surgery: 0% vs 13.2%, P = .15). Corneal graft failure arising after trabeculectomy was seen in 10.0% of DSAEK cases and in 10.5% of PK controls (P = 1.0).

CONCLUSION

Compared to trabeculectomy after PK, trabeculectomy after DSAEK achieved lower mean IOP at 12 months, and a larger proportion of DSAEK patients achieved an IOP of less than 12 mm Hg. There was no difference in the need for intervention after trabeculectomy, or incidence of other complications. Trabeculectomy is an effective surgical procedure for the management of postgraft ocular hypertension in DSAEK patients, and DSAEK may have an advantage in terms of success of trabeculectomy surgery over PK.

The role of mast cells in wound healing

Mast cells are predominantly found in the vicinity of connective tissue vessels of skin and mucosa. The main immunological functions of mast cells are in IgE-mediated reactions and in helminth infestations. Mast cells respond to tissue injury by releasing inflammatory mediators and have been implicated in diseases of excessive fibrosis of the dermis such as scleroderma. Current evidence suggests that mast cells exert its role during inflammation and cellular proliferation. Animal models have shown that by stabilising mast cells at the early stages of wound healing, wound contraction is reduced. Mast cells are an ideal candidate to play a pivotal role in wound healing due to its location, substances released and clinical associations.