Doxycycline-a role in ocular surface repair

Low Rate of Postoperative Pterygium Recurrence in Patients under Treatment with Low-Dose Oral Doxycycline for Chronic Blepharitis: A First Report

PURPOSE

Low doses of systemic doxycycline (LD-SD) inhibit angiogenesis and the expression of matrix metalloproteases, which are determinants of pterygium progression. This study aimed to compare the recurrence rate and visual outcome of pterygium excision in patients undergoing chronic treatment with LD-SD for chronic refractory blepharitis and LD-SD-naive patients.

METHODS

A retrospective analysis of patients that underwent surgical excision and conjunctival graft apposition was conducted. Patients were divided in a TETRA group (under LD-SD treatment at the moment of surgery) and a control group. The main outcome was the rate of recurrence at 1 year postoperatively. Secondary outcomes were the comparisons of surface regularity, visual quality, and dry-eye symptoms at 6-week, 6-month, and 1-year follow-up in the two groups.

RESULTS

The TETRA group showed a significantly lower rate of 1-year recurrence both in primary (p = 0.034) and recurrent (p < 0.001) pterygia. The best corrected visual acuity (BCVA), astigmatic error, corneal total root mean square (RMS), and ocular surface disease index (OSDI) significantly reduced during the follow-up in both groups. The surface asymmetry index and high-order aberrations (HOAs) significantly reduced only in the TETRA group. The final BCVA was significantly higher, while the OSDI score and total RMS and HOAs were significantly lower in the TETRA group compared to the control.

CONCLUSIONS

Patients under treatment with LD-SD showed a lower rate of recurrence at 1-year follow-up compared to controls. These patients also experienced higher BCVA and surface regularity and less dry-eye symptoms.

The role of matrix metalloproteinases in infectious corneal ulcers

During infectious keratitis, the production of collagenolytic and inflammatory substances, along with increased corneal matrix metalloproteinase (MMP) activity, induces the degradation of corneal collagen and may cause postkeratitis complications, such as opacity, thinning, and corneal perforation. MMPs, especially MMP-2 and MMP-9, are overexpressed in infectious keratitis and sustained over time by inflammatory and nonmicrobial mechanisms. The high MMP levels are correlated with excessive corneal destruction in bacterial, herpetic, fungal, and acanthamoeba infections. Nonspecific treatments, such as tetracyclines, particularly doxycycline, or corticosteroids, are used as adjuvants to antimicrobials to alleviate the disproportionate degradation and inflammation of the corneal layers caused by corneal MMPs and decrease the recruitment and infiltration of inflammatory cells. Treatments showing inhibition of specific MMPs (Galardin, ZHAWOC7726), interfering with pro-MMP activation (EDTA, ascorbic acid), or showing anticytokine effect (epigallocatechin-2-gallate, TRAM-34) have been reported. Other treatments show a direct action over corneal collagen structure such as corneal cross-linking or have been associated with reduction of MMP levels such as amniotic membrane grafting. Although the use of these drugs has been shown in studies to be effective in controlling inflammation, especially in experimental ones, robust studies are still needed based on randomized and randomized clinical trials to demonstrate their potential effect as adjuvants in the management of infectious keratitis.

Oral doxycycline for early bleb leak after trabeculectomy: A case report and review of literature

We report the adjuvant role of oral doxycycline therapy for the management of early bleb leaks post mitomycin-augmented trabeculectomy. Two glaucoma patients, who underwent trabeculectomy with mitomycin C, presented with a low intraocular pressure (IOP) in the early postoperative period. Both patients had moderately elevated bleb with Seidel's positive test. Oral doxycycline 100 mg twice daily was given for 1 week in addition to routine postoperative management. Post doxycycline therapy at 1 week, healing of the wound was noted, with a negative Seidel's test. The IOP was maintained at 3 months postoperatively in both patients.

Can Serum Drops Containing Doxycycline Provide a Supplemental Anti-Bacterial Effect in the Treatment of Bacterial Keratitis?

PURPOSE

Systemic doxycycline has been prescribed to reduce inflammation and enhance corneal healing in bacterial keratitis. Topical autologous serum drops (ASD) containing doxycycline following oral supplementation may additionally confer an anti-bacterial effect. The potential of this supplementation was evaluated by determining the in vitro susceptibility of bacterial keratitis isolates to doxycycline.

METHODS

The minimum inhibitory concentrations (MICs) of doxycycline against 100 bacterial keratitis isolates were determined using Etests. Twenty-seven Staphylococcus aureus, ten coagulase-negative Staphylococci, six Streptococcus pneumoniae, seven viridans group streptococci, seven other Gram-positive bacteria, nineteen Pseudomonas aeruginosa, eight Serratia marcescens, four Moraxella spp., two Haemophilus spp., and ten other Gram-negative bacteria isolates were tested. MICs of doxycycline were compared to a serum standard concentration of doxycycline (SSCD) of 4 µg/mL and concentrations that would be found in 50% and 20% serum component clinical preparations of ASD, corresponding to 50% SSCD (2 µg/mL) and 20% SSCD (0.8 µg/mL), respectively. MICs equal to or less than these values were used to deem a bacterial isolate susceptible.

RESULTS

For Gram-positive bacteria, susceptibilities to SSCD, 50% SSCD, and 20% SSCD were 86%, 65%, and 60%, respectively. For Gram-negative bacteria, susceptibilities to SSCD, 50% SSCD, and 20% SSCD were 37.2%, 23.3%, and 11.6%, respectively. Chi-squared analyses comparing Gram-positive and Gram-negative susceptibilities showed significantly greater susceptibility of Gram-positive bacteria at all three tested MICs (<0.0001, <0.0001, <0.0001).

CONCLUSIONS

Our data suggest that autologous serum drops containing theoretic concentrations of doxycycline may provide an additional anti-bacterial effect in the treatment of bacterial keratitis, especially for Gram-positive bacterial keratitis compared to Gram-negative bacterial keratitis.

Superior limbic keratoconjunctivitis: Update on pathophysiology and management

Superior limbic keratoconjunctivitis (SLK) is an under-recognized condition characterized by a final common pathologic presentation of superior conjunctival and limbal inflammation and staining. Existing literature attributes both microtrauma and local inflammation, frequently in the setting of tear film insufficiency, as the underlying mechanisms that lead to a self-perpetuating pathologic process dependent in on inflammatory cells and signaling. Effective treatments act by targeting inflammation and by mitigating mechanical stressors. This critical review discusses the latest in our understanding of the pathophysiology of SLK and how it guides our treatment strategies.

Investigation of the Effect of pH on the Adsorption-Desorption of Doxycycline in Feed for Small Ruminants

Orally administered tetracycline antibiotics interact with feed, which may impact their bioavailability and efficacy. Therefore, the pH-dependent adsorption of doxycycline and its interaction with feed for ruminants was studied in vitro. Adsorption experiments on animal feed (135 and 270 mg) with initial doxycycline concentrations of 35, 75, and 150 µg/mL were performed. Desorption experiments were conducted by agitation of a predetermined mass of doxycycline-loaded animal feed in PBS, at pH = 3.0, 6.0, and 7.4, to simulate changes in the gastrointestinal tract. Antibiotic concentrations were determined by LC-MS/MS analysis. The adsorption/desorption of doxycycline was described by mathematical models. Chemisorption with strong intermolecular interactions between the active functional groups of doxycycline and the organic biomass was found. The experimental release curve comprised three sections: initial prolonged 27-30% release (pH = 6.0), followed by moderate 56-59% release (pH = 3.0), and final 63-74% release (pH = 7.4). The sigmoidal model showed a considerable role of diffusion with an initial prevalence of desorption and a decreased desorption rate thereafter. The Weibull equation revealed an initial release stage followed by a lag time section and sustained release. The study of doxycycline adsorption by the animal feed proved a maximum 80% encapsulation efficiency and revealed initial diffusion followed by chemisorption. The highest release efficiency of 74% suggests high bioavailability of doxycycline after oral administration in ruminants.

Challenges and concepts in the diagnosis and management of ocular graft-versus-host disease

Graft-versus-host disease (GVHD) is characterized by tissue inflammation in the host following an allogeneic hematopoietic cell transplantation (HCT). The pathophysiology is complex and only incompletely understood yet. Donor lymphocyte interaction with the histocompatibility antigens of the host plays a crucial role in the pathogenesis of the disease. Inflammation may affect multiple organs and tissues, e.g., the gastrointestinal tract, liver, lung, fasciae, vaginal mucosa, and the eye. Subsequently, alloreactive donor-derived T and B lymphocytes may lead to severe inflammation of the ocular surface (i.e., cornea and conjunctiva) and the eyelids. Furthermore, fibrosis of the lacrimal gland may lead to severe dry eye. This review focuses on ocular GVHD (oGVHD) and provides an overview of current challenges and concepts in the diagnosis and management of oGVHD. Ophthalmic manifestations, diagnostic procedures, grading of severity and recommendations for ophthalmic examination intervals are provided. Management of ocular surface disease with lubricants, autologous serum eye drops, topical anti-inflammatory agents and systemic treatment options are described based on the current evidence. Ocular surface scarring and corneal perforation are severe complications of oGVHD. Therefore, ophthalmic screening and interdisciplinary treatment approaches are highly relevant to improve the quality of life of patients and to prevent potentially irreversible visual loss.

Corneal complications of rheumatoid arthritis

PURPOSE OF REVIEW

Rheumatoid arthritis (RA) is an autoimmune disease that primarily affects the joints. Extra-articular manifestations (EAMs) are common and may affect up to 40.6% of patients. Ocular EAM can occur in 39% of the patients. The cornea is involved by different pathogenic mechanisms and corneal disease varies from mild symptoms to severe corneal ulceration and melting with visual loss. Severe corneal involvement is associated with increased mortality in RA patients. We aimed to review the prevalence, mechanisms, management and overall impact of corneal involvement in RA patients.

RECENT FINDINGS

Corneal involvement is frequent among RA patients. With the wider use of systemic immunosuppression, in particular the disease-modifying antirheumatic drugs (DMARDs), and with improvement of surgical techniques, spontaneous and surgery-related corneal ulceration and melting is becoming less common. However, RA patients are still at risk and should be carefully managed.

SUMMARY

RA-related corneal complications are associated with a decreased quality of life and poor ocular and systemic prognosis. Prompt recognition and a multidisciplinary approach involving topical ophthalmic management and systemic immunosuppression are the key factors to maintain ocular integrity and avoid a lethal outcome.

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.

Amniotic membrane transplantation for acute ocular burns

BACKGROUND

Ocular surface burns can be caused by chemicals (alkalis and acids) or direct heat. One effect of the burn is damage to the limbal epithelial stem cells of the ocular surface with delayed re-epithelialisation, stem cell failure, and conjunctivalisation of the cornea. Amniotic membrane transplantation (AMT) performed in the acute phase (day 0 to day 7) following an ocular surface burn is claimed to reduce pain and accelerate healing. The surgery involves securing a layer of amniotic membrane (AM) to the eyelid margins as a patch to cover the entire ocular surface. However, there is debate about the severity of an ocular burn that may benefit from AMT and uncertainty of whether AMT improves outcomes.

OBJECTIVES

To compare the effect of AMT with medical therapy in the first seven days after an ocular surface burn, compared to medical therapy alone.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2021, Issue 9); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the WHO ICTRP. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 29 September 2021.

SELECTION CRITERIA

We included randomised trials that compared an AMT applied in the first seven days following an ocular surface burn in addition to medical therapy with medical therapy alone. The outcome measures were failure of re-epithelialisation by day 21 post injury, visual acuity at final follow-up, corneal neovascularisation, symblepharon, time to re-epithelialisation and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results, assessed the included studies for risk of bias and extracted relevant data. We contacted trial investigators for missing information. We summarised data using risk ratios (RRs) and mean differences (MDs) as appropriate.

MAIN RESULTS

We analysed two RCTs, but excluded individual patients who had been treated outside the acute phase in one of the studies (data provided by study authors). In total, 36 moderate burns from one RCT and 92 severe burns from two RCTs were evaluated separately. For both categories, the certainty of the evidence was downgraded principally as a result of high risks of performance and detection biases, and because of imprecision indicated by very wide confidence intervals. In addition, follow-up was insufficiently frequent to calculate time-to-epithelialisation precisely. Moderate severity ocular burns (Roper-Hall classification II-III) The relative risk of AMT on failure of epithelialisation by day 21 was 0.18 (0.02 to 1.31), and LogMAR visual acuity was 0.32 lower (0.55 to 0.09 lower) in the treatment group (i.e. better), suggesting a possible benefit of AMT. The GRADE assessment for failure of epithelialisation by day 21 was downgraded to very low due to the risk of bias and imprecision (very wide confidence intervals including no effect). The GRADE assessment for visual acuity at final follow-up was downgraded to low due to the risk of bias and imprecision (optimal information size not met). The relative effects of AMT on corneal neovascularisation (RR 0.56; 0.21 to 1.48), symblepharon (RR 0.41; 0.02 to 9.48) and time-to-epithelialisation (13 days lower; 26.30 lower to 0.30 higher) suggest possible benefit of AMT, but the wide confidence intervals indicate that both harm and benefit are possible. GRADE assessments for these outcomes were once again downgraded to very low due to the risk of bias and imprecision. Since adverse effects are rare, the small sample would have fewer occurrences of rare but potentially important adverse effects. The GRADE assessment for adverse effects was therefore considered to be low.  Severe ocular burns (Roper-Hall classification IV) The relative risk of AMT on failure of epithelialisation by day 21 was 1.03 (0.94 to 1.12), and LogMAR visual acuity was 0.01 higher (0.29 lower to 0.31 higher) in the treatment group (i.e, worse), indicating no benefit of AMT. GRADE assessments for failure of epithelialisation by day 21 and final outcomes were downgraded to low. The relative effects of AMT on corneal neovascularisation (RR 0.84; 0.66 to 1.06), symblepharon (RR 0.89; 0.56 to 1.42) and time-to-epithelialisation (1.66 days lower; 11.09 lower to 7.77 higher) may include both benefit and harm. GRADE assessments for corneal neovascularisation, symblepharon and time-to-epithelialisation were downgraded to low due to risk of bias and imprecision. For adverse effects, the GRADE assessment was downgraded to low, reflecting the small sample sizes in the RCTs.

AUTHORS' CONCLUSIONS

There is uncertain evidence to support the treatment of moderate acute ocular surface burns with AMT in addition to standard medical therapy as a means of preventing failure of epithelialisation by day 21, improving visual outcome and reducing corneal neovascularisation, symblepharon formation and time-to-epithelialisation. For severe burns, the available evidence does not indicate any significant benefit of treatment with AMT.

Visual Outcomes of Patients With Peripheral Ulcerative Keratitis and the Effect of Immunosuppression-A 6-Year Experience in Queensland, Australia

OBJECTIVE

Peripheral ulcerative keratitis (PUK) can cause significant ocular morbidity and mortality. This study aimed to review the effects of systemic immunosuppression on visual outcomes.

METHODS

A state-wide, retrospective case series based in Queensland, Australia, was performed. A review of patients who presented with PUK to the major tertiary ophthalmology referral centers between January 2015 and January 2021 was undertaken. Parameters recorded included clinical features at presentation, investigations undertaken, treatment provided, visual outcomes, and mortality outcomes. The effect of immunomodulatory therapy on the change in vision from presentation to the most recent review was analyzed.

RESULTS

Twenty-two eyes of 26 patients with PUK (average age 69.81±14.54 years) were included and had a mean follow-up period of 577.73 days. Twelve patients (54.5%) had systemic autoimmune disease, one patient (4.5%) had positive syphilis serology, and nine patients (40.9%) had idiopathic PUK. Eighteen patients (81.8%) were treated with systemic steroids and 10 patients (45.5%) were treated with steroid-sparing immunomodulatory therapy. Average logarithm of the minimum angle of resolution best-corrected visual acuity (BCVA) at presentation and final follow-up were 0.63±0.65 and 0.64±0.82, respectively. Those who were treated with immunomodulatory therapy had a nonstatistically significant improvement in BCVA (-0.10±0.29 with vs. +0.10±0.35 without), and a similar trend was seen for doxycycline (-0.08±0.09 with vs. +0.22±0.49 without). Four of five perforations (80%) were surgically managed. Four patients (18.2%) were deceased.

CONCLUSIONS

Peripheral ulcerative keratitis poses significant clinical challenges and requires intensive medical treatment, frequently involving systemic immunomodulatory therapy. Surgical treatment is required in a significant minority of cases. Ocular management alongside the use of doxycycline and immunomodulatory therapy in consultation with specialist physicians can optimize visual and systemic outcomes.

Genipin Delays Corneal Stromal Enzymatic Digestion

Purpose

To evaluate the use of genipin in delaying enzymatic digestion of corneal stroma.

Methods

Human corneal stromal tissue was treated with genipin, a known chemical crosslinker, and then along with control tissue was subjected to enzymatic digestion with collagenase. The effects of genipin treatment in retarding stromal digestion were analyzed with phase contrast microscopy, a protein quantification assay, second harmonic generation imaging, and transmission electron microscopy.

Results

Genipin increased stromal resistance to enzymatic digestion when compared with untreated stroma. A morphologic analysis and protein quantification showed increased stromal resistance to enzymatic digestion once stromal tissue was treated with genipin. Second harmonic generation imaging revealed persistent fibrillar collagen signaling in genipin-treated tissue in contrast with untreated tissue suggesting that genipin retards collagenolysis.

Conclusions

Genipin increases stromal resistance to enzymatic digestion in controlled experiments as demonstrated by protein quantification studies and through morphologic imaging.

Translational Relevance

This study explores the novel use of genipin in delaying enzymatic stromal digestion. Delaying stromal melting in the setting of corneal infectious or autoimmune keratitis can potentially decrease clinical morbidity.

A Review of Ocular Graft-versus-Host Disease: Pathophysiology, Clinical Presentation and Management

Graft-versus-host disease is a common complication following allogeneic hematopoetic stem cell transplantation that can affect multiple organ systems, including the eyes. Ocular GVHD (oGVHD) is characterized by a T cell-mediated immune response that leads to immune cell infiltration and inflammation of ocular structures, including the lacrimal glands, eyelids, cornea and conjunctiva. oGVHD has a significant negative impact on visual function and quality of life and successful management requires a multi-disciplinary approach with frequent monitoring. Here, we review the pathophysiology and clinical presentation of oGVHD, along with current therapeutic strategies based on our clinical experience and the reported literature.

Stepwise candidate drug screening for myopia control by using zebrafish, mouse, and Golden Syrian Hamster myopia models

Background

We developed a preclinical protocol for the screening of candidate drugs able to control myopia and prevent its progression. The protocol uses zebrafish, C57BL/6 mice, and golden Syrian hamster models of myopia.

Methods

A morpholino (MO) targeting the zebrafish lumican gene (zlum) was injected into single-cell zebrafish embryos, causing excessive expansion of the sclera. A library of 640 compounds with 2 matrix metalloproteinase (MMP) inhibitors (marimastat and batimastat), which have the potential to modulate scleral remodelling, was screened to identify candidates for mitigating scleral diameter expansion in zlum-MO-injected embryos. The myopia-prevention ability of compounds discovered to have superior potency to inhibit scleral expansion was validated over 4 weeks in 4-week-old C57BL/6 mice and 3-week-old golden Syrian hamsters with form-deprivation myopia (FDM). Changes in the refractive error and axial length were investigated. Scleral thickness, morphology of collagen fibrils in the posterior sclera, messenger RNA (mRNA) expressions, and protein levels of transforming growth factor-β2 (TGF-β2), tissue inhibitor of metalloproteinase-2 (TIMP-2), MMP-2, MMP-7, MMP-9, and collagen, type I, alpha 1 (collagen Iα1) were investigated in C57BL/6 mice, and MMP-2, MMP-9, and MMP activity assays were conducted in these mice.

Findings

In the zebrafish experiment, atropine, marimastat, batimastat, doxycycline, and minocycline were the drugs that most effectively reduced expansion of scleral equatorial diameter. After 28-day treatment in diffuser-wearing mice and 21-day treatment in lid-sutured hamsters, myopic shift and axial elongation were significantly mitigated by eye drops containing 1% atropine, 50 µM marimastat, 5 µM batimastat, or 200 µM doxycycline. MMP-2 mRNA expression in mouse sclera was lower after treatment with atropine, marimastat, batimastat, or doxycycline. The protein levels and activity of MMP-2 and MMP-7 were significantly reduced after treatment with atropine, marimastat, batimastat, doxycycline, and minocycline. Furthermore, scleral thickness and collagen fibril diameter were not lower after treatment with atropine, marimastat, batimastat, or doxycycline than those of occluded eyes.

Interpretation

Stepwise drug screening in a range of models from zlum-MO-injected zebrafish to rodent FDM models identified effective compounds for preclinical myopia control or prevention. On the basis of the 640 compounds that were screened, MMP inhibitors may offer alternatives for clinical trials.

Funding

This research was supported by grants from Taiwan's Ministry of Science and Technology and Ministry of Health and Welfare.

Peripheral ulcerative keratitis

Peripheral ulcerative keratitis (PUK) is an inflammatory condition of the peripheral cornea with hallmark features of epithelial defects and stromal destruction as a result of a complex interplay of factors including host autoimmunity and the peculiar anatomic and physiologic features of the peripheral cornea and environmental factors. PUK may be the result of local or systemic causes and infectious or noninfectious causes. Arriving at a specific etiological diagnosis requires a meticulous clinical workup that may include a battery of laboratory and radiological investigations. Management by a team of internists or rheumatologists and ophthalmologists and judicious use of immunosuppressive agents may yield favorable results minimizing adverse effects. We review current clinical knowledge on the diagnosis and management of PUK.

Experience in managing glaucoma filtration surgery complications with oral doxycycline: A case series

PURPOSE

To report the clinical profile and effectiveness of oral doxycycline as a non-invasive treatment for glaucoma filtering surgery complications.

METHOD

Prospective case series.

RESULTS

Doxycycline is widely used in treating corneal melts, ocular surface diseases, meibomian gland disease, recurrent epithelial cell erosion, rosacea, and keratitis sicca. This prospective case series highlights the successful treatment of five patients with leaking blebs and conjunctiva erosion from glaucoma filtration surgery with the use of oral doxycycline. There was no adverse event reported in our cases.

CONCLUSIONS

This study suggests that oral doxycycline may be a feasible non-surgical treatment modality due to its ability to inhibit collagenolysis, restore the Meibomian gland function, thereby stopping breakdown and promote conjunctival tissue healing.

Case Report: A Polymicrobial Vision-Threatening Eye Infection Associated with Polysubstance Abuse

We report a patient with risk factors for both microbial keratitis and endophthalmitis, which were initially challenging to distinguish. Cultures of corneal scrapings yielded several organisms, including an uncultivable Gram-negative rod, eventually identified as Kingella negevensis. Kingella negevensis is so named because most strains have been isolated in the Negev, a desert region of southern Israel. The epidemiology of K. negevensis remains incompletely understood. We found no other reports in the literature of this organism causing microbial keratitis.

The Wound Healing Effect of Doxycycline after Corneal Alkali Burn in Rats

Purpose

To evaluate the wound healing effect of doxycycline and its underlying mechanisms in a rat model of corneal alkali burn.

Methods

Male SD rats were administered 1.0 N NaOH in the right cornea for 25 seconds and randomly divided into the doxycycline group and the control group, with 84 rats in each group. 1.0 g·L⁻¹ doxycycline eye drops (doxycycline group) or vehicle (control group) was topically instilled onto the rat cornea after chemical injury. Three days, 7 days, and 14 days after alkali burn, microscopy was used to observe corneal wound healing by fluorescein staining and the degree of corneal opacity. The expression of transforming growth factor-beta 1 (TGF-β1) and matrix metalloproteinase-9 (MMP-9) was detected by RT-PCR and ELISA, alpha-smooth muscle actin (a-SMA) levels were measured by immunofluorescent staining, and Western blot assays for TGF-β1, a-SMA, and nuclear factor-kappa B (NF-κB) were also performed.

Results

Corneal wound healing and corneal opacity scores were better in the doxycycline group than in the control group. Three, 7, and 14 days after corneal alkali burn, a significant increase in TGF-β1 was observed in corneas from the control group, compared with the corneas from the doxycycline group (P < 0.05). The corneal levels of MMP-9 in the doxycycline group were lower than those in the control group 3 days and 7 days after alkali burn (P < 0.05). In addition, doxycycline inhibited α-SMA expression and suppressed NF-κB expression.

Conclusion

Doxycycline treatment promoted corneal healing and reduced corneal opacity in SD rats. Doxycycline protected the cornea from alkali burn injury by reducing TGF-β1, MMP-9, NF-κB, and α-SMA expression.

Role of corneal nerves in ocular surface homeostasis and disease

Corneal nerves are key components of the physiological system that controls ocular surface homeostasis. The cornea is primarily innervated by the ophthalmic branch of the trigeminal nerves (cranial nerve V), which distend bilaterally from the pons. The nasociliary branch (afferent) of the ophthalmic nerve is sensory for cornea, eyelid and conjunctiva. These nerve fibres play a role in sensing temperature, chemical and mechanical stimuli, and pain, whereas, branches of the facial nerve (cranial nerve VII) contain motor nerves that control blinking and autonomic (sympathetic and a paucity of parasympathetic) fibres that stimulate tear production and secretion via feedback loops between the ocular surface, lacrimal glands and brain. Disruption of these nerves with interruption of neural feedback loops between the ocular surface and lacrimal glands can lead to corneal diseases such as dry eye disease (DED) and neurotrophic keratopathy (NK). Inversely, hypersensitivity of the nerve fibres and/or dysregulation of pain-controlling nervous centres may lead to neuropathic pain. Recently, medications that specifically target regeneration of corneal nerves have started to become available - and considering the high prevalence of diseases associated with corneal nerve dysfunction, these agents promise to fulfil a hitherto important unmet need. In this review, we explore the physiology of corneal nerves, the pathology of corneal nerve diseases and how these relate to neuropathic pain, NK and DED. We also discuss what novel treatments may be useful against diseases involving corneal nerves.

Oral doxycycline and azithromycin in the management of recurrent conjunctival dehiscence following glaucoma drainage implantation in a child

Aqueous drainage devices play an important role in the treatment of refractory glaucomas; however, they can be associated with early and late postoperative complications, including conjunctival dehiscence, which must be repaired surgically. Recurrent dehiscence despite surgical repair is uncommon and can be sight threatening. We discuss possible causes and management options of recurrent conjunctival dehiscence in a 2-year-old and the role of oral doxycycline and azithromycin in its management.

Corneal toxicity induced by vesicating agents and effective treatment options

The vesicating agents sulfur mustard (SM) and lewisite (LEW) are potent chemical warfare agents that primarily cause damage to the ocular, skin, and respiratory systems. However, ocular tissue is the most sensitive organ, and vesicant exposure results in a biphasic injury response, including photophobia, corneal lesions, corneal edema, ulceration, and neovascularization, and may cause loss of vision. There are several reports on ocular injury from exposure to SM, which has been frequently used in warfare. However, there are very few reports on ocular injury by LEW, which indicate that injury symptoms appear instantly after exposure and faster than SM. In spite of extensive research efforts, effective therapies for vesicant-induced ocular injuries, mainly to the most affected corneal tissue, are not available. Hence, we have established primary human corneal epithelial cells and rabbit corneal organ culture models with the SM analog nitrogen mustard, which have helped to test the efficacy of potential therapeutic agents. These agents will then be further evaluated against in vivo SM- and LEW-induced corneal injury models, which will assist in the development of potential broad-spectrum therapies against vesicant-induced ocular injuries.

[Ophthalmologic manifestation of granulomatosis with polyangiitis (Wegener's granulomatosis)]

Granulomatosis with polyangiitis (GPA), formerly earlier known as Wegener's granulomatosis, is primary system necrotizing vasculitis of small and medium-sized vessels, which is characterized by the formation of foci of granulomatous inflammation. One of the target organs in GPA is the organ of vision. Its affection may not only reduce quality of life, but also may lead to the severest complications even to fatal outcome. The affection varies in severity from slight inflammation of the ocular superficial structures to severe involvement of all orbital and ocular structures to develop complete blindness, including bilateral one. GPA can affect any portion of the organ of vision. The changes are low specific, which makes early diagnosis and timely adequate therapy difficult. Overall all ophthalmologic manifestations can be divide into 4 groups: 1) lesions of the orbit and appendages; 2) those of the conjunctiva and fibrous tunic of the eyeball: 3) those of the retina: 4) those of the optic nerve. Orbital affection is characterized by the development of granulomas, dacryoadenitis with marked inflammatory infiltration of the surrounding tissues, including oculomotor muscles, and destruction of orbital bony walls. Nonspecific conjunctivitis and episcleritis are commonly encountered. Affection of the fibrous tunic of the eyeball is characterized by the development of necrotizing scleritis, peripheral ulcerative or stromal keratitis. The retina is rarely involved and mainly described as sporadic cases in the literature. The optic nerve is most commonly damaged due to the compression of the orbit by inflamed tissue; the lesion is more infrequently ischemic.

Role of oral doxycycline and large diameter bandage contact lens in the management of early post-trabeculectomy bleb leak

A 27-year-old man with juvenile open angle glaucoma and medically uncontrolled intraocular pressure (IOP) underwent a trabeculectomy with mitomycin C in his right eye. One week postoperatively, he developed ischaemic necrosis of the conjunctiva with a bleb leak. This was managed conservatively with oral doxycycline 100 mg twice daily along with a topical low-dose steroid, antibiotic and cycloplegic and a large diameter bandage contact lens (BCL). There was dramatic improvement in the bleb appearance, the necrosis healed and the leak resolved. The patient had well-controlled IOP with a diffuse healthy bleb at 4 weeks, which was maintained at 2 years. This case illustrates the utility and importance of oral doxycycline in the management of early post-trabeculectomy conjunctival necrosis and the use of BCL in the management of a bleb leak. This safe and non-invasive method not only hastened the recovery but also helped in maintaining good bleb function.

Ocular surface disease exacerbated glaucoma: optimizing the ocular surface improves intraocular pressure control

PURPOSE

To describe a series of 4 patients with inadequately controlled primary open angle glaucoma and ocular surface disease (OSD) in whom a combination approach was used to manage the OSD resulting in improved intraocular pressure (IOP) control.

PATIENTS AND METHODS

A retrospective review of the clinical notes of 4 patients referred to a tertiary surgical glaucoma service was performed. At the initial visit, measures to control the OSD were employed in all patients; twice-daily lid hygiene measures, a 3-month course of 50 mg daily oral doxycycline, topical carmellose sodium (celluvisc) 0.5% 4 to 6 times daily, and preservative-free equivalents of topical antiglaucoma medications as deemed appropriate, depending on the perceived severity of the OSD.

RESULTS

Patients were reviewed for a maximum of 24 months after intervention. In all patients treatment resulted in a marked symptomatic and clinical improvement in the ocular surface with a reduction in hyperemia, meibomian gland dysfunction and superficial keratopathy. A reduction in the IOP also occurred in all patients, obviating the need for glaucoma drainage surgery during the study period.

CONCLUSIONS

Patients with severe OSD often have glaucoma that is refractive to medical therapy. Furthermore, the surgical success of glaucoma filtering surgery is compromised in patients with scarring and inflammation of the conjunctiva. The term we postulate is "OSD exacerbated glaucoma." This is the first study to suggest that the use of a combination approach comprising medical treatment to manage the OSD in patients with primary open angle glaucoma may lead to an improvement in the IOP control and the management of glaucoma.

The effect of topical doxycycline on corneal neovascularization

PURPOSE

To examine the effect of topical doxycycline on human corneal neovascularization (CONV).

MATERIALS AND METHODS

Six eyes of six patients with CONV received topical 1% doxycycline four times per day for three weeks and monitored for a total of one year. Ophthalmic evaluations included visual acuity, tonometry, slit-lamp examination, conjunctival swabs, quantification of CONV and photography.

RESULTS

CONV either disappeared or was attenuated, shortened and less dense in five of six patients. There were no adverse effects.

CONCLUSION

Topical doxycycline was effective in reducing CONV and healing of the ocular surface.

Molecular modeling-based inclusion mechanism and stability studies of doxycycline and hydroxypropyl-β-cyclodextrin complex for ophthalmic delivery

The aim of the present study was to prepare a stable complex of doxycycline (Doxy) and hydroxypropyl-β-cyclodextrin (HPβCD) for ophthalmic delivery and investigate the inclusion mechanism and the inclusion effects on the stability of Doxy. The Doxy/HPβCD complex was prepared by solution stirring and then characterized by scanning electron microscopy and ultraviolet spectroscopy. Based on results of nuclear magnetic resonance, molecular model of Doxy/HPβCD complex was established using computational simulation of PM3 method implemented in Gaussian 03. Stabilities of Doxy/HPβCD complex in both aqueous solution and solid state at 25°C were evaluated by HPLC. Finally, in vitro antibacterial activity of the Doxy/HPβCD complex was evaluated by disk diffusion test. It was found that the stabilities of Doxy/HPβCD complex in both aqueous solution and solid state were improved obviously as compared with Doxy alone. This stability enhancement is consistent with the inclusion mechanism between HPβCD and Doxy, which showed that the unstable site of Doxy molecule at 6-CH3 was protected in the hydrophobic cavity of HPβCD, additionally, the chelation of Mg2+ provided a synergetic protection of the other unstable site of Doxy at 4-N(CH3)2. The antibacterial activity results indicated that Doxy/HPβCD complex might have potential for clinical applications.

Amniotic membrane transplantation for acute ocular burns

BACKGROUND

Ocular surface burns can be caused by chemicals (alkalis and acids) or by direct heat. Amniotic membrane transplantation (AMT) performed in the acute phase (day 0 to day 7) of an ocular surface burn is reported to relieve pain, accelerate healing and reduce scarring and blood vessel formation. The surgery involves applying a patch of amniotic membrane (AM) over the entire ocular surface up to the eyelid margins.

OBJECTIVES

To assess the effects of AMT on the eyes of people having suffered acute ocular surface burns.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 6), MEDLINE (January 1946 to June 2012), EMBASE (January 1980 to June 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to June 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 11 June 2012.

SELECTION CRITERIA

We included randomised trials of medical therapy and AMT applied in the first seven days after an ocular surface burn compared to medical therapy alone.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias of included studies and extracted relevant data. We contacted trial investigators for missing information. We summarised data using risk ratios (RRs) and mean differences (MDs) as appropriate.

MAIN RESULTS

We included one RCT of 100 participants with ocular burns that were randomised to treatment with AMT and medical therapy or medical therapy alone. A subset of patients (n = 68) who were treated within the first seven days of the injury met the inclusion criteria and were included in the analysis. The remaining 32 eyes were excluded. The included subset consisted of 36 moderate (Dua classification II-III) and 32 severe (Dua classification IV-VI) ocular burns from alkali, acid and thermal injuries. In the moderate category, 13/20 control eyes and 14/16 treatment eyes had complete epithelialisation by 21 days. The RR of failure of epithelialisation by day 21 was 0.18 in the treatment group (95% confidence interval (CI) 0.02 to 1.31; P = 0.09). Mean LogMAR final visual acuities were 0.06 (standard deviation (SD) 0.10) in the treatment group and 0.38 (SD 0.52) in the control group, representing a MD of -0.32 (95% CI -0.05 to -0.59). In the severe category, 1/17 treatment and 1/15 control eyes were epithelialised by day 21. The RR of failure of epithelialisation in the treatment group was 1.01 (95% CI 0.84 to 1.21; P = 0.93). Final visual acuity was 1.77 (SD 1.31) in the treated eyes and 1.64 (SD 1.48) in the control group (MD 0.13; 95% CI -0.88 to 1.14). The risks of performance and detection biases were high, because treating personnel and outcome assessors could not be masked to treatment. There was also a high risk of bias in the visual outcomes of the moderate category, since mean visual acuity was significantly worse at presentation in the control eyes. This reduced confidence in the study findings.

AUTHORS' CONCLUSIONS

Conclusive evidence supporting the treatment of acute ocular surface burns with AMT is lacking. Heterogeneity of disease presentation, variations in treatment, undefined criteria for treatment success and failure, and non-uniform outcome measures are some of the factors complicating the search for clear evidence regarding this treatment.

Silibinin, dexamethasone, and doxycycline as potential therapeutic agents for treating vesicant-inflicted ocular injuries

There are no effective and approved therapies against devastating ocular injuries caused by vesicating chemical agents sulfur mustard (SM) and nitrogen mustard (NM). Herein, studies were carried out in rabbit corneal cultures to establish relevant ocular injury biomarkers with NM for screening potential efficacious agents in laboratory settings. NM (100nmol) exposure of the corneas for 2h (cultured for 24h), showed increases in epithelial thickness, ulceration, apoptotic cell death, epithelial detachment microbullae formation, and the levels of VEGF, cyclooxygenase-2 (COX-2) and matrix metalloproteinase-9 (MMP-9). Employing these biomarkers, efficacy studies were performed with agent treatments 2h and every 4h thereafter, for 24h following NM exposure. Three agents were evaluated, including prescription drugs dexamethasone (0.1%; anti-inflammatory steroid) and doxycycline (100nmol; antibiotic and MMP inhibitor) that have been studied earlier for treating vesicant-induced eye injuries. We also examined silibinin (100μg), a non-toxic natural flavanone found to be effective in treating SM analog-induced skin injuries in our earlier studies. Treatments of doxycycline+dexamethasone, and silibinin were more effective than doxycycline or dexamethasone alone in reversing NM-induced epithelial thickening, microbullae formation, apoptotic cell death, and MMP-9 elevation. However, dexamethasone and silibinin alone were more effective in reversing NM-induced VEGF levels. Doxycycline, dexamethasone and silibinin were all effective in reversing NM-induced COX-2 levels. Apart from therapeutic efficacy of doxycycline and dexamethasone, these results show strong multifunctional efficacy of silibinin in reversing NM-induced ocular injuries, which could help develop effective and safe therapeutics against ocular injuries by vesicants.

Effect of doxycycline on postoperative scarring after trabeculectomy in an experimental rabbit model

PURPOSE

To investigate effectiveness of doxycycline after trabeculectomy in rabbits by evaluating bleb appearance, intraocular pressure, and levels of matrix metalloproteinase-1, -2, -3, and -9 and tissue inhibitors of metalloproteinase (TIMP)-1 and -2 in the subconjunctival (sc) area.

METHODS

Twenty-nine New Zealand White rabbits were assigned into 1 of 6 groups as follows: topical doxycycline (0.1%), postoperative sc injection of doxycycline (100 mg/2 mL), and intraoperative mitomycin-C (MMC) (0.2 mg/mL) and their respective control groups.

RESULTS

There was significant difference between intraocular pressure in the case groups, but there was no significant difference in topical doxycycline and MMC groups during the follow up. In the topical doxycycline group, levels of TIMP-1 and perifericTIMP-1 were higher and levels of perifericMMP-2 and inflammation were lower than their controls. In the sc doxycycline group, peripheral inflammation was higher than in the corresponding control. Only peripheral inflammation was significantly different between case groups, with the highest level in sc and the lowest level in MMC groups. Further, topical doxycycline group showed no significant difference in bleb appearance or peripheral inflammation compared with MMC group. Conjunctival burn and corneal vascularization were detected only in the sc doxycycline group.

CONCLUSIONS

Topical doxycycline is more effective than sc doxycycline but is similar to MMC, and it can be an alternative to MMC in trabeculectomy in rabbits.

Ocular manifestations of ANCA-associated vasculitis

The antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides-Wegener's granulomatosis, microscopic polyangiitis, and Churg-Strauss syndrome-can present with various ophthalmic manifestations. In a subset of patients, these findings may be the earliest indicators of systemic disease. Orbital and anterior segment findings are most common, whereas posterior segment complications such as retinal vasculitis and optic neuropathy occur much less frequently. This article describes the distinguishing features of associated ophthalmic disease, focusing on the manifestations clinicians are most likely to encounter and those with the most significant ocular morbidity. Although the ANCA-associated vasculitides require systemic workup and treatment, this article discusses diagnostic and therapeutic modalities often used concurrently for ophthalmic disease.

The effect of doxycycline temperature-sensitive hydrogel on inhibiting the corneal neovascularization induced by BFGF in rats

BACKGROUND

To study the effect of doxycycline temperature-sensitive hydrogel (DTSH) on inhibiting the corneal neovascularization (NV) induced by the basic fibroblast growth factor (bFGF).

METHODS

Corneal NV was induced by slow-release polymer pellets containing bFGF, using a rat corneal pocket model. After being implanted with bFGF pellets, the female Sprague-Dawley rats were randomly divided into seven groups (12 rats/group). The grouped rats were given topically normal saline solution and neutralized DTSH at a concentration of 0%, 0.01%, 0.05%, 0.1%, 0.5%, and 1% respectively, and treated for 6 consecutive days. After 6 days of treatment, the cornea was perfused with India ink. The length and area of the corneal vessel were measured and analyzed by Image Pro-Plus 5.1.

RESULTS

Compared to the control group given saline solution, the study groups given DTSH at a concentration of 0.05%, 0.1%, 0.5%, and 1% showed significant reduction in the vessel length (respectively, 58%, 60%, 52%, and 37%) and the vessel area (respectively, 61%, 62%, 49%, and 39%) (p < 0.001). However, no such significant reduction was observed in the study group given 0.01% DTSH (p = 0.133 and 0.166 for vessel length and area respectively). Study groups given 0.05% and 0.1% DTSH showed better effects than groups given 0.01% and 1% DTSH with regard to reducing the vessel length and the vessel area (p < 0.05).

CONCLUSION

The study results showed that topical DTSH effectively inhibited corneal NV at the ideal concentration of 0.05% and 0.1%. Therefore, topical DTSH could be considered as an alternative treatment for the clinical management of corneal NV.

Pediatric ocular rosacea

A case of severe pediatric ocular rosacea was effectively treated after 2.5 years of misdiagnosis. A high index of suspicion should be maintained in children with ocular surface disease, with or without dermatologic rosacea, to correctly diagnose ocular rosacea and avoid morbidity and complications.

In vivo characterization of doxycycline effects on tear metalloproteinases in patients with chronic blepharitis

PURPOSE

Matrix metalloproteinases (MMPs) have a role in the pathogenesis of rosacea-associated chronic blepharitis. Doxycycline is largely used as a treatment for recalcitrant chronic blepharitis. It has been shown in vitro that doxycycline inhibits MMPs activation. The aim of this study was to investigate in vivo the effect of doxycycline in modulating MMPs in patients with chronic idiopathic blepharitis.

METHODS

Eight patients (6 male, 2 female; mean age 45.7+/-17.5 years) were included in the study. Doxycycline (100 mg) was administered orally, twice a day, for 2 weeks and once a day for an additional 2 weeks. Clinical signs and symptoms were evaluated and scored (0-3) at baseline and after 4 weeks. Total sign (TSS) and total symptom (TSyS) scores were calculated. Tear samples and conjunctival impression cytologies were collected at baseline and after 4 weeks of treatment to evaluate MMP-9 and TIMP-1 expression and activity.

RESULTS

An improvement in TSS (4.5+/-1.1 vs 2.7+/-1.5) and TSyS (6.6+/-1.3 vs. 3.1+/-1.9) was observed after 4 weeks, with significant amelioration of hyperemia, marginal blepharitis, and superficial punctuate keratopathy. Zymography revealed a decrease of MMP-9 activity after 4 weeks. MMP-9 mRNA and protein levels did not change, while an upregulation of TIMP-1 expression was observed.

CONCLUSIONS

This study suggests that 4-week treatment with doxycycline significantly improved symptoms and signs in patients with chronic blepharitis in association with a decrease in MMP-9 activity. Upregulation of TIMP-1 is proposed as a possible mechanism of MMP-9 inactivation.

Tear fluid concentration of mmp-8 is elevated in non-allergic eosinophilic conjunctivitis and correlates with conjunctival inflammatory cell infiltration

BACKGROUND

To investigate tear fluid concentration of matrix metalloproteinase 8 (MMP-8) and its relation to conjunctival inflammatory cell infiltration in persistent non-allergic eosinophilic conjunctivitis (NAEC).

METHODS

Two groups were included: 26 consecutive adult patients with NAEC (conjunctival eosinophils at least 1+ [1-10 eosinophils/slide], skin prick test [SPT] to common allergens negative), and 26 asymptomatic adult persons (no conjunctival eosinophils, SPT negative). MMP-8 tear fluid concentrations were determined by immunofluorometric assay, and conjunctival brush cytology samples from NAEC patients were used for MMP-8 immunocytochemistry. Gelatin zymography was used to illustrate proteolytic activity within the tear fluid samples.

RESULTS

The mean MMP-8 concentration was significantly higher among NAEC patients (214.3 +/- 327.7 microg/l) than among healthy persons (50.4 +/- 62.3 microg/l, P < 0.0001). In the NAEC patients, tear fluid MMP-8 correlated with the numbers of conjunctival neutrophils (r = 0.66, P = 0.0002) as well as with goblet cells and columnar epithelial cells (r = 0.54 for both, P = 0.045), but not with the lymphocyte numbers (r = -0.36, P = 0.0741). By immunocytology, MMP-8 protein could also be detected in vivo in the inflammatory cell population within the conjunctiva. Zymography revealed that proteolysis was significantly higher in the NAEC group, and activated enzymes were practically found only in the NAEC group.

CONCLUSIONS

The results showed that NAEC is an inflammatory condition characterized by increased tear fluid MMP-8 levels, probably derived from both inflammatory and structural conjunctival cells. The increased proteolytic activity in NAEC patients may indicate risk of conjunctival structural changes (remodeling).