Effect of latanoprost and timolol on the histopathology of the human conjunctiva

Outcome of combined trabeculectomy with cataract surgery in patients on prostaglandin analogs and aqueous suppressants

PURPOSE

To compare the effect of prostaglandin analogs (PGA) against other glaucoma medications (non-PGA) on the intraocular pressure (IOP) outcomes of combined trabeculectomy with phacoemulsification, and the conjunctival cell profile in persons with primary open-angle (POAG) and pseudoexfoliation glaucoma (PXFG).

METHODS

A prospective cohort study was conducted among 116 patients with POAG or PXFG on glaucoma medications for a minimum of 3 months undergoing glaucoma triple procedure. Patients were divided into two groups (PGA and non-PGA) based on preoperative exposure to PGA. IOP outcomes were assessed for up to 2 years. Conjunctival biopsy specimens were obtained at the time of surgery, and histopathological analysis was performed.

RESULTS

Forty-two patients were in the PGA group, 67 were in the non-PGA group, and seven were lost to follow-up. The non-PGA group had lesser mean postoperative IOP and needed fewer postoperative medications compared to the PGA group in all visits up to 2 years. The non-PGA group had better complete success rate (50.7% vs. 14.3%, P < 0.001). Kaplan-Meier survival estimates showed a significant difference in cumulative complete success rate between non-PGA (67%) and PGA (26%) by 24 months ( P < 0.001). The Cox proportional model showed the type of drug to be significantly associated with surgical failure. Histopathological analysis revealed that the PGA group had higher numbers for each type of inflammatory cell (except mast cells) compared to the non-PGA group.

CONCLUSION

Patients on PGA are likely to have a higher postoperative IOP and may need more medications for IOP control after a glaucoma triple procedure.

Ocular surface disease: a known yet overlooked side effect of topical glaucoma therapy

Ocular surface disease (OSD), a disorder affecting the lacrimal and meibomian glands and the corneal and conjunctival epithelium, is a well-known complication of topical glaucoma therapy. OSD can present as a new or pre-existing condition that virtually any anti-glaucoma formulation can exacerbate. As such, both glaucoma and OSD frequently coexist. Typical OSD symptoms include ocular discomfort, redness, burning, and dryness, whereas signs include periorbital and eyelid skin pigmentation, conjunctival scarring, and superficial punctate keratitis. Pressure-lowering eyedrops can cause toxic, allergic, and inflammatory reactions on the ocular surface. The latter can result from either preservatives or direct toxicity from the active molecule. Although usually mild, OSD can cause significant symptoms that lead to poor quality of life, decreased compliance to therapy, glaucoma progression, and worse visual outcomes. Given the chronic nature of glaucoma, lack of curative therapy, and subsequent lifelong treatment, addressing OSD is necessary. This manuscript aims to provide an up-to-date overview of OSD's signs, symptoms, and pathogenic mechanisms from glaucoma therapy toxicity.

Matrix Metalloproteinases and Glaucoma

Matrix metalloproteinases (MMPs) are enzymes that decompose extracellular matrix (ECM) proteins. MMPs are thought to play important roles in cellular processes, such as cell proliferation, differentiation, angiogenesis, migration, apoptosis, and host defense. MMPs are distributed in almost all intraocular tissues and are involved in physiological and pathological mechanisms of the eye. MMPs are also associated with glaucoma, a progressive neurodegenerative disease of the eyes. MMP activity affects intraocular pressure control and apoptosis of retinal ganglion cells, which are the pathological mechanisms of glaucoma. It also affects the risk of glaucoma development based on genetic pleomorphism. In addition, MMPs may affect the treatment outcomes of glaucoma, including the success rate of surgical treatment and side effects on the ocular surface due to glaucoma medications. This review discusses the various relationships between MMP and glaucoma.

Preparing the ocular surface for glaucoma filtration surgery: an unmet clinical need

The mutual relationship among medical therapy, ocular surface (OS) and filtration surgery (FS) represents one of the most crucial issues in glaucoma management. As the long-term use of intraocular pressure-lowering medications significantly affect the OS health, patients with an uncontrolled disease frequently undergo glaucoma surgery in less-than-ideal conditions. As we known, OS changes strongly affect the post-operative bleb filtration capability. Therefore, improving the OS conditions before proceeding with FS is needed. Currently, given the rapid diffusion of new surgical procedures, this need is even more perceived. Nevertheless, despite surgeons retain the OS preparation of primary importance, and recognize the OS disease (OSD) as the only modifiable risk factor for filtration failure, there is no agreement on which strategies should be preferred to prepare patients. This is largely due to the lack of validated guidelines, which forces clinicians to adopt personal approaches based on evidence derived from low-quality studies. In this review, we provided an overview of risk factors involved in the FS failure, with particular attention to those depending on OS changes, and how OSD negatively affects the aqueous humor resorption after surgery. Moreover, we reported the most exploited measures to mitigate the OSD before surgery, the possible reasons underlying the absence of shared approaches, and the upcoming area of intervention to preserve the OS health during glaucoma management. Finally, based on the current evidence, we proposed a pre-operative outline reporting the main risk factors that should be considered before surgery, and the therapeutical options available to improve the OS.

Comparison of the Efficacy and Safety of Trabeculectomy with Mitomycin C According to Concentration: A Prospective Randomized Clinical Trial

(1) Background: Mitomycin C (MMC) is commonly used during trabeculectomy. However, there is no consensus on which concentration should be used. We aimed to compare the efficacy and safety of 0.2 mg/mL and 0.4 mg/mL of MMC in eyes undergoing trabeculectomy. (2) Methods: Thirty-six eyes (36 glaucoma patients) were randomized to undergo a trabeculectomy with 0.2 mg/mL or 0.4 mg/mL of MMC. The success rate was evaluated according to three criteria: (A) intraocular pressure (IOP) ≤ 18 mmHg and IOP reduction ≥ 20%; (B) IOP ≤ 15 mmHg and IOP reduction ≥ 25%; (C) IOP ≤ 12 mmHg and IOP reduction ≥ 30%. Cox’s proportional hazard model was used to identify the predictive factors for failure. Immunohistochemical procedures for matrix metalloproteinase (MMP) were performed on Tenon’s tissue. Bleb morphology was evaluated. Safety was assessed based on the incidence of complications. (3) Results: Of the 36 eyes, 19 underwent trabeculectomy with 0.2 mg/mL of MMC and 17 with 0.4 mg/mL. The success rates were 75%, 67%, and 47% at 6 months for criteria A, B, and C, respectively. There were no significant differences between the two groups. High MMP-9 staining and low preoperative IOP were associated with failure (hazard ratio (HR), 5.556; p = 0.033, and HR, 0.936; p = 0.033). Complications included hypotony in two eyes (6%), hyphema in one eye (3%), and choroidal detachment in one eye (3%). (4) Conclusions: Trabeculectomy with 0.2 mg/mL and 0.4 mg/mL of MMC showed similar IOP-control effects to those recorded in previous studies, along with a low rate of complications. There was no significant difference in efficacy or safety between the 0.2 mg/mL and 0.4 mg/mL MMC groups.

Conjunctival thickness as a predictive imaging biomarker for the glaucoma filtration surgery outcome: An optical coherence tomography study

IMPORTANCE

To analyse the preoperative conjunctival thickness in glaucomatous patients undergoing filtration surgery (FS), using optical coherence tomography (OCT).

BACKGROUND

The conjunctival status represents one of the most critical determinants of the FS outcome.

DESIGN

Retrospective study.

PARTICIPANTS

Sixty-seven patients candidate to FS for uncontrolled glaucoma were enrolled.

METHODS

OCT was performed at the superior bulbar conjunctiva before FS, and at bleb site at the last follow-up (LF-up) after surgery.

MAIN OUTCOME MEASURES

Preoperative full, epithelial, and stromal conjunctival thickness (FCT, CET, CST) and reflectivity (CR), and LF-up bleb-wall thickness (BT), reflectivity (BR) and intraocular pressure (IOP), were the major outcomes. The relations between preoperative parameters and LF-up-IOP, BT and BR were calculated.

RESULTS

FS was completely successful in 23 patients (group 1), successful with medications in 22 (group 2), and failed in 22 (group 3). FCT, CET and CST were lower, whereas CR higher, in group 3 compared to groups 1 and 2 (P < .05); BT was lower (P < .001), whereas BR higher (P < .05) in group 3 compared to group 1. FCT and CST were predictors of FS outcome with lower thickness associated with increased odds of failure (odds ratio 0.922, P = .08; 0.941, P = .025). LF-up-IOP inversely correlated with FCT and CST (r = -0.447, P = .003; r = -0.408, P = .007), whereas positively correlated with CR (r = 0.789, P < .001).

CONCLUSIONS AND RELEVANCE

Preoperative conjunctival thickness and reflectivity show significant correlations with the FS outcome, both in terms of IOP and bleb-wall features. Therefore, they may be proposed as predictive imaging biomarkers to estimate the risk of filtration failure.

Conjunctival structure of glaucomatous eyes treated with anti-glaucoma eye drops: a cross-sectional study using anterior segment optical coherence tomography

BACKGROUND

To determine the effect of various factors to the preservation rate of the conjunctival layer borderlines of glaucomatous eyes treated with anti-glaucoma eye drops.

METHODS

Anterior segment optical coherence tomography (AS-OCT) images of the bulbar conjunctiva of 328 eyes were analyzed with and without anti-glaucoma eye drops to quantify the preservation rates of the conjunctival layer borderlines.

RESULTS

More anti-glaucoma eye drops and a longer duration of administration were associated with lower preservation rates of the borderlines between both the conjunctival stroma/Tenon's capsule (P < 0.001 and P < 0.001, respectively) and Tenon's capsule/sclera (P < 0.001 and P < 0.001, respectively). Prostaglandin analogs and fixed combinations of β-blockers/prostaglandin analogs were prognostic factors for lower preservation rates of the borderlines between both the conjunctival stroma/Tenon's capsule (P < 0.001 and P = 0.009, respectively) and Tenon's capsule/sclera (P < 0.001 and P = 0.008, respectively).

CONCLUSIONS

Numerous anti-glaucoma eye drops and their long-term administration are associated with the disruption of the bulbar conjunctival borderlines detected by AS-OCT.

Matrix Metalloproteinases and Glaucoma Treatment

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade extracellular matrix (ECM) components such as collagen and have important roles in multiple biological processes, including development and tissue remodeling, both in health and disease. The activity of MMPs is influenced by the expression of MMPs and tissue inhibitors of metalloproteinase (TIMPs). In the eye, MMP-mediated ECM turnover in the juxtacanalicular region of the trabecular meshwork (TM) reduces outflow resistance in the conventional outflow pathway and helps maintain intraocular pressure (IOP) homeostasis. An imbalance in the MMP/TIMP ratio may be involved in the elevated IOP often associated with glaucoma. The prostaglandin analog/prostamide (PGA) class of topical ocular hypotensive medications used in glaucoma treatment reduces IOP by increasing outflow through both conventional and unconventional (uveoscleral) outflow pathways. Evidence from in vivo and in vitro studies using animal models and anterior segment explant and cell cultures indicates that the mechanism of IOP lowering by PGAs involves increased MMP expression in the TM and ciliary body, leading to tissue remodeling that enhances conventional and unconventional outflow. PGA effects on MMP expression are dependent on the identity and concentration of the PGA. An intracameral sustained-release PGA implant (Bimatoprost SR) in development for glaucoma treatment can reduce IOP for many months after expected intraocular drug bioavailability. We hypothesize that the higher concentrations of bimatoprost achieved in ocular outflow tissues with the implant produce greater MMP upregulation and more extensive, sustained MMP-mediated target tissue remodeling, providing an extended duration of effect.

Ocular Surface Changes in Prostaglandin Analogue-Treated Patients

Glaucoma is the second leading cause of blindness globally. Reducing intraocular pressure (IOP) has been acknowledged to be the main therapy for glaucoma. Prostaglandin analogues (PGAs) have become the first-line therapy for patients with glaucoma due to their powerful efficacy for lowering (IOP). However, usage of PGAs can also cause several notable side effects, including the changes in ocular surface. The relationship between PGAs and ocular surface changes is complicated and still remains unclear. In the present review, we summarize the recent studies of the effects of PGAs on ocular changes as well as the possible mechanisms that might provide new considerations during clinical medication.

How many aqueous humor outflow pathways are there?

The aqueous humor (AH) outflow pathways definition is still matter of intense debate. To date, the differentiation between conventional (trabecular meshwork) and unconventional (uveoscleral) pathways is widely accepted, distinguishing the different impact of the intraocular pressure on the AH outflow rate. Although the conventional route is recognized to host the main sites for intraocular pressure regulation, the unconventional pathway, with its great potential for AH resorption, seems to act as a sort of relief valve, especially when the trabecular resistance rises. Recent evidence demonstrates the presence of lymphatic channels in the eye and proposes that they may participate in the overall AH drainage and intraocular pressure regulation, in a presumably adaptive fashion. For this reason, the uveolymphatic route is increasingly thought to play an important role in the ocular hydrodynamic system physiology. As a result of the unconventional pathway characteristics, hydrodynamic disorders do not develop until the adaptive routes cannot successfully counterbalance the increased AH outflow resistance. When their adaptive mechanisms fail, glaucoma occurs. Our review deals with the standard and newly discovered AH outflow routes, with particular attention to the importance they may have in opening new therapeutic strategies in the treatment of ocular hypertension and glaucoma.

Effects of aqueous suppressants and prostaglandin analogues on early wound healing after glaucoma implant surgery

A hypertensive phase frequently develops in the early postoperative period after glaucoma shunt operations. Anti-glaucoma eye drop use is essential when postoperative intraocular pressure (IOP) is not controlled. We investigated whether the use of early topical anti-glaucoma medication affects wound healing following glaucoma tube surgery. Eyes were randomly assigned to receive topical aqueous suppressant (timolol-dorzolamide fixed combination), prostaglandin (PG) analogue (travoprost), or normal saline (control group). First, we observed the effects of topical eye drops on Tenon’s tissue in non-operated eyes in rabbits. Second, we examined the effects of these eye drops on rabbit eyes that underwent Ahmed glaucoma drainage device implantation, including the effects on the histopathological appearance of their blebs. Interleukin-2 in the Tenon’s tissue was elevated in the PG group when compared to the control and aqueous suppressant groups (P = 0.006). In non-operated eyes, IOP was similar among the groups (P = 0.545). After glaucoma implant surgery, the average height of the inner collagenous layer and the average height of the α-SMA-positive blebs were the least in the aqueous suppressant group (P = 0.013, P = 0.001, respectively) at 4 weeks postoperatively. IOP was lower in the aqueous suppressant group than that in the control and PG groups (P = 0.001) following tube surgery. After Ahmed tube surgery, early treatment with aqueous suppressant decreased fibrosis in the bleb, but early treatment with the PG analogues did not.

Effect of long-term topical latanoprost medication on conjunctival thickness in patients with glaucoma

AIM

To investigate the effect of long-term use of topically administered latanoprost on conjunctival thickness (CT) and conjunctival epithelium thickness (CET) in the patients with glaucoma.

METHODS

A series of 106 glaucomatous patients were included. Of the 106 eyes, 55 eyes were treated with latanoprost eye drops once a day (latanoprost group), while 51 eyes were treated with carteolol hydrochloride eye drops (carteolol group). All the included patients completed a 2-year follow-up. CT and CET were measured with optical coherence tomography (OCT) in all patients at presentation and at 2-year visit, respectively. Statistical analysis was then performed to compare the change in CT and CET.

RESULTS

At presentation, there was no difference in CET (t=0.400, P=0.689) or CT (t=1.14, P=0.259) between the two groups. No significant difference was found in CET (61.65±5.35 µm at baseline, 60.36±6.36 µm at 2-year follow-up, respectively; t=1.977, P=0.0531), while there was a significant decrease in CT from 201.45±14.99 µm at baseline to 167.81±14.57 µm at 2-year visit (t=14.1407, P<0.001) in the latanoprost group. At 2-year follow-up, no statistically difference was found in CET (62.24±5.27 µm; t=1.086, P=0.282) or CT (201.23±12.45 µm; t=1.44, P=0.154) compared to it at baseline (CET: 61.23±5.42 µm; CT: 198.76±13.68 µm, respectively) in the carteolol group.

CONCLUSION

A significant decrease in conjunctival thickness is found in glaucoma patients treated with long-term topical latanoprost; its potential effect on the outcome of filtration surgery should be considered.

In Vivo Analysis of Prostaglandins-induced Ocular Surface and Periocular Adnexa Modifications in Patients with Glaucoma

BACKGROUND/AIM

Prostaglandin analogues (PGAs) are a first-line medical treatment for glaucoma because of their powerful intraocular pressure (IOP) lowering effect, few systemic side-effects (SEs), and the once daily administration. Despite the high systemic safety profile, the chronic use of PGAs may induce periocular and ocular surface (OS)-related side effects, which affect a significant proportion of glaucomatous patients. In this review, we summarize the current knowledge about SEs of PGAs on periocular structures and OS, and their implications in clinical practice.

MATERIALS AND METHODS

A comprehensive literature search on the PubMed platform was performed. Two hundred fifty articles fulfilling key words were identified, of which 180 were excluded since they did not concern the effects of PGAs on the periocular tissues and OS, or because of their limited relevance. The following key words were used and combined, to narrow-down the literature: "prostaglandin" and "ocular surface," which identified 184 unique publications, of which 68 were selected; "prostaglandin" and "periocular" which identified 46 unique publications, of which 11 were selected. An additional search was conducted using "prostaglandin" and "Meibomian glands (MGs)", which identified twenty unique publications, of which 8 were selected. Thus, a total of 70 articles were chosen based on their relevance and were included in this review.

RESULTS

Prostaglandin-associated peri-orbitopathy, skin pigmentation and hypertrichosis, eyelash growth, and MGs dysfunction are the most frequent modifications of periocular tissues. They are induced by the tissue accumulation of PGAs, and FP receptor stimulation. Without preservatives, PGAs act as stimulators of conjunctival goblet cells, which are the main source of ocular surface mucoproteins, and seem to increase conjunctival epithelium microcysts proposed as in vivo hallmark of the trans-scleral aqueous humour outflow. Additional PGA-induced modifications can be recognized in the cornea, corneo-scleral limbus, conjunctival stroma and, conjunctiva-associated lymphoid tissue, mainly appearing as inflammatory changes. OS epithelia desquamation, chemosis, apoptosis, dendritic cell activation, conjunctival or episcleral vasodilation, and sub-basal nerve plexus disruption were also described in patients receiving preserved PGAs.

CONCLUSION

PGAs induce several modifications of the OS structures and adnexa; nonetheless, none of them significantly reduces the local safety profile of this class of drugs. Moreover, the OS changes do not affect the IOP lowering efficacy of PGAs. On these bases, local SEs of PGAs should not discourage clinicians in using this class of medications because of their efficacy, the systemic safety profile, and the better adherence.

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.

Matrix metalloproteinases (MMP-1, MMP-2, MMP-3 and MMP-9, and TIMP-1, TIMP-2 and TIMP-3) and markers for vascularization in functioning and non-functioning bleb capsules of glaucoma drainage implants

PURPOSE

To investigate and compare functioning versus non-functioning glaucoma drainage implant (GDI) capsules for selective markers of extracellular matrix degradation and vascularity.

METHODS

In three samples of both functioning and non-functioning blebs, immunohistochemistry was used to determine the expression of MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, TIMP-3 and CD31. A non-functioning bleb was defined as IOP >21 mmHg or <20% reduction in IOP from baseline with maximal tolerated medication. The samples were classified into five grades based on immunostaining: no staining, no significant staining, mild, moderate or marked staining.

RESULTS

Expression of MMP-1, MMP-2 and MMP-3 was mostly low in both functioning and non-functioning blebs. However, immunostaining of MMP-9 was marked in samples taken from functioning GDIs and correlated with the presence of vascular profiles in the luminal bleb. CD31 immunoreactivity was more intense in the outer layers of the bleb than in the inner layers. In non-functioning blebs, immunoreactivity for TIMP-3 was significant through the whole bleb wall, but only mild in the inner zone of functioning blebs. TIMP-1 and TIMP-2 were barely detectable.

CONCLUSION

Staining of TIMP-3 was seen to be lower in the vicinity of the small blood vessels. In avascular bleb wall, increased expression of TIMP-3 suggests its potential role in the inhibition of angiogenesis as reported previously in vivo. The abundance of MMP-9 in bleb capsule wall of relatively old patients might lead to weakened bleb capsule wall architecture and increasing filtration of aqueous humour through the capsule, which are reflected in a lower IOP.

Effects of Long-Term Antiglaucoma Eye Drops on Conjunctival Structures: An In Vivo Confocal Microscopy Study

Purpose. The study was aimed at comparing the long-term effects of different antiglaucoma eye drops on conjunctival structures using laser scanning confocal microscopy. Methods. Eighty patients diagnosed with primary open-angle glaucoma and twenty healthy volunteers were included in this study. The participants were divided into 5 groups according to the different medications. The lachrymal film break-up time, Schirmer's I test, and Ocular Surface Disease Index Questionnaire were performed in all subjects. The confocal microscopy was used to observe the basal epithelial cell density (ECD), goblet cell density (GCD), dendritic cell density (DCD), and subepithelial collagen fiber diameter (SFD). Results. Statistically significant differences were found among the control group and the antiglaucoma therapy groups in the values of three clinical data (P < 0.05). The GCD, DCD, and SFD showed significant differences in all glaucoma groups when compared to the control (P < 0.001). Moreover, the prostaglandin group differed from the other antiglaucoma therapy groups in the GCD and SFD (P < 0.05). Conclusions. Our study confirmed the significant differences in the conjunctival structures based on the effects of antiglaucoma medications. Less pronounced changes were found in the patients treated with prostaglandin analogue than in the other kinds of antiglaucoma therapies.

Conjunctival matrix metalloproteinases and their inhibitors in glaucoma patients

PURPOSE

Chronic conjunctival inflammation, caused by various reasons, for example long-term use of topical drugs and/or their preservatives, affects the outcome of glaucoma surgery by interfering with wound healing. Matrix metalloproteinases (MMPs) remodel extracellular matrix (ECM) and are involved in the wound healing process. This study was designed to evaluate the conjunctival expression of MMPs and their tissue inhibitors (TIMPs) in the normal eye, primary open-angle glaucoma (POAG) and exfoliation glaucoma (ExG) and whether there is an association between staining intensities and deep sclerectomy outcome.

METHODS

Immunohistochemical procedures were performed on conjunctival samples which were obtained from POAG (n=11) and ExG (n=14) patients as well as normal (n=7) subjects. Antibodies against MMPs (MMP-1, -2, -3 and -9) and TIMPs (TIMP-1, -2 and -3) were used.

RESULTS

In conjunctival stroma, expression levels of MMP-2 (p=0.047), MMP-3 (p=0.009), MMP-9 (p<0.001), TIMP-1 (p=0.003), TIMP-2 (p<0.001) and TIMP-3 (p<0.001) in ExG and MMP-9 (p=0.008), TIMP-2 (p=0.02) and TIMP-3 (p=0.002) in POAG were significantly increased compared to control. We further found correlations between expression of MMP-1 and MMP-3 and the length of pilocarpine treatment.

CONCLUSION

The expression of MMPs and TIMPs is increased in the conjunctiva of POAG and ExG patients having a long history of topical antiglaucoma drops. Antiglaucoma agents and/or their preservatives alter the remodelling balance of ECM in conjunctiva of POAG and ExG eyes. The balance between MMPs and TIMPs may play a crucial role in the conjunctival wound healing process and the outcome of glaucoma surgery.

Trans-conjunctival aqueous humor outflow in glaucomatous patients treated with prostaglandin analogues: an in vivo confocal microscopy study

PURPOSE

To analyze, using in vivo laser scanning confocal microscopy (LSCM), the conjunctival features in glaucomatous patients receiving prostaglandin analogues (PGA).

METHODS

Eighty eyes of 80 consecutive glaucomatous patients naive for therapy were enrolled; 30 eyes of 30 healthy subjects served as a control. Patients were randomized to: preservative-free (PF) and preserved latanoprost (groups 1 and 2, respectively), PF and preserved timolol (groups 3 and 4), and controls to vehicle of latanoprost or physiological buffered saline solution (groups 5 and 6). All subjects underwent LSCM of bulbar conjunctiva at baseline and 3 months after initiating therapy. The main outcomes were: mean density (MMD: cysts/mm(2)) and mean area (MMA: cysts/mm(2)) of epithelial microcysts. The relations between MMA and MMD with intraocular pressure (IOP), age, and mean defect (MD), were analyzed.

RESULTS

At baseline, microcysts were found in all subjects. At month three, MMD did not change in all groups (p > 0.05). MMA significantly increased only in group 1 from 2,158.81 ± 524.09 to 3,877.77 ± 867.31, and in group 2 from 2,019.71 ± 541.03 to 5,560.39 ± 1,176.14, with values significantly higher in group 2 (p < 0.001). Significant relations were not found between MMD and MMA with IOP, MD, and age (p > 0.05).

CONCLUSIONS

PGA increased MMA in therapy-naive glaucomatous patients, indicating a possible enhancement of the trans-conjunctival aqueous humor outflow. Therefore, conjunctiva seems an additional target tissue to evaluate the hydrodynamic pathways in glaucoma and modifications induced by medical therapy.

[Modern filtration surgery. An update]

Preoperative treatment with steroids and nonsteroidal anti-inflammatory drugs increases the success of filtration surgery. Surgery with the patient under subconjunctival anesthesia is safe. Intraoperative application of mitomycin C is state of the art and enhances success rates. Perioperative use of bevacizumab seems to attenuate postoperative fibrosis. Postoperative hypotension is avoided by stable fixation of the scleral flap followed by stepwise controlled suturelysis or release. Transconjunctival flap suturing allows fast and simple treatment of overfiltration. The shorter the time lag between trabeculectomy and subsequent cataract surgery the higher the probability of bleb failure will be. The number of antiglaucomatous drugs and severity of glaucomatous damage before surgery correlate with the probability of failure and blindness.

Novel usage of intraocular pressure-lowering drugs as wound-healing inhibitors after trabeculectomy with cell culture and animal models

Inhibiting the healing of wounds to ensure that the aqueous humor can drain into the scleral space unimpeded and form a filtering bleb plays a crucial role in determining the success rate of glaucoma surgery. The aim of this study was to investigate the novel use, with cell culture and animal models, of some commercial intraocular pressure (IOP)-lowering drugs in inhibiting the healing of fibroblast wounds. The Tenon's fibroblasts of rabbits were cultured to evaluate 13 IOP-lowering drugs for cellular proliferation, collagen formation, and migration. These were measured using [(3)H]thymidine and [(3)H]proline uptake, and Transwell chambers. A preservative of benzalkonium chloride (BAK) was initially used, with 0.02% as a maximal original concentration. All of the drugs and the BAK were diluted from original commercial concentrations to 1/10, 1/100, and 1/1000. The more inhibitive drugs screened from the cell cultures were then selected for further short-term application during and after trabeculectomy surgeries had been performed on the rabbits. Expression of the proliferative cell nuclear antigen was immunohistochemically examined 3 and 7 days after surgery. The results revealed that the inhibitive effects of BAK in cellular [(3)H]thymidine and [(3)H]proline uptake, and cellular migration were only evident at 0.002% concentrations. Based on the results of the cell cultures, timolol, latanoprost, and unoprostone exhibited a greater inhibitory effect than the other drugs. Moreover, the animal studies showed that latanoprost and unoprostone significantly suppressed the positive expression of proliferative cell nuclear antigen around the operative excision area 7 days after the trabeculectomy surgeries. The results indicate that short-term use of some IOP-lowering drugs, such as latanoprost and unoprostone, may inhibit postoperative wound healing after glaucoma surgery.

Preservatives in eyedrops: the good, the bad and the ugly

There is a large body of evidence from experimental and clinical studies showing that the long-term use of topical drugs may induce ocular surface changes, causing ocular discomfort, tear film instability, conjunctival inflammation, subconjunctival fibrosis, epithelial apoptosis, corneal surface impairment, and the potential risk of failure for further glaucoma surgery. Subclinical inflammation has also been described in patients receiving antiglaucoma treatments for long periods of time. However, the mechanisms involved, i.e., allergic, toxic, or inflammatory, as well as the respective roles of the active compound and the preservative in inducing the toxic and/or proinflammatory effects of ophthalmic solutions, is still being debated. The most frequently used preservative, benzalkonium chloride (BAK), has consistently demonstrated its toxic effects in laboratory, experimental, and clinical studies. As a quaternary ammonium, this compound has been shown to cause tear film instability, loss of goblet cells, conjunctival squamous metaplasia and apoptosis, disruption of the corneal epithelium barrier, and damage to deeper ocular tissues. The mechanisms causing these effects have not been fully elucidated, although the involvement of immunoinflammatory reactions with the release of proinflammatory cytokines, apoptosis, oxidative stress, as well as direct interactions with the lipid components of the tear film and cell membranes have been well established. Preservative-induced adverse effects are therefore far from being restricted to only allergic reactions, and side effects are often very difficult to identify because they mostly occur in a delayed or poorly specific manner. Care should therefore be taken to avoid the long-term use of preservatives, otherwise a less toxic alternative to BAK should be developed, as this weakly allergenic but highly toxic compound exerts dose- and time-dependent effects. On the basis of all these experimental and clinical reports, it would be advisable to use benzalkonium-free solutions whenever possible, especially in patients with the greatest exposure to high doses or prolonged treatments, in those suffering from preexisting or concomitant ocular surface diseases, and those experiencing side effects related to the ocular surface. Indeed, mild symptoms should not be underestimated, neglected, or denied, because they may very well be the apparent manifestations of more severe, potentially threatening subclinical reactions that may later cause major concerns.