RETINAL TOXICITY OF INTRAVITREAL KENALOG IN ALBINO RABBITS

The prophylactic value of TNF-α inhibitors against retinal cell apoptosis and optic nerve axon loss after corneal surgery or trauma

BACKGROUND AND PURPOSE

Late secondary glaucoma is an often-severe complication after acute events like anterior segment surgery, trauma and infection. TNF-α is a major mediator that is rapidly upregulated, diffusing also to the retina and causes apoptosis of the ganglion cells and degeneration of their optic nerve axons (mediating steps to glaucomatous damage). Anti-TNF-α antibodies are in animals very effective in protecting the retinal cells and the optic nerve-and might therefore be useful prophylactically against secondary glaucoma in future such patients. Here we evaluate (1) toxicity and (2) efficacy of two TNF-α inhibitors (adalimumab and infliximab), in rabbits by subconjunctival administration.

METHODS

For drug toxicity, animals with normal, unburned corneas were injected with adalimumab (0.4, 4, or 40 mg), or infliximab (1, 10, or 100 mg). For drug efficacy, other animals were subjected to alkali burn before such injection, or steroids (for control). The rabbits were evaluated clinically with slit lamp and photography, electroretinography, optical coherence tomography, and intraocular pressure manometry. A sub-set of eyes were stained ex vivo after 3 days for retinal cell apoptosis (TUNEL). In other experiments the optic nerves were evaluated by paraphenylenediamine staining after 50 or 90 days. Loss of retinal cells and optic nerve degeneration were quantified.

RESULTS

Subconjunctival administration of 0.4 mg or 4.0 mg adalimumab were well tolerated, whereas 40.0 mg was toxic to the retina. 1, 10, or 100 mg infliximab were also well tolerated. Analysis of the optic nerve axons after 50 days confirmed the safety of 4.0 mg adalimumab and of 100 mg infliximab. For efficacy, 4.0 mg adalimumab subconjunctivally in 0.08 mL provided practically full protection against retinal cell apoptosis 3 days following alkali burn, and infliximab 100 mg only slightly less. At 90 days following burn injury, control optic nerves showed about 50% axon loss as compared to 8% in the adalimumab treatment group.

CONCLUSIONS

Subconjunctival injection of 4.0 mg adalimumab in rabbits shows no eye toxicity and provides excellent neuroprotection, both short (3 days) and long-term (90 days). Our total. accumulated data from several of our studies, combined with the present paper, suggest that corneal injuries, including surgery, might benefit from routine administration of anti-TNF-α biologics to reduce inflammation and future secondary glaucoma.

The Evolution of Triamcinolone Acetonide Therapeutic Use in Retinal Diseases: From Off-Label Intravitreal Injection to Advanced Nano-Drug Delivery Systems

Ophthalmic drug delivery to the posterior segment of the eye has been challenging due to the complex ocular anatomy. Intravitreal injection of drugs was introduced to deliver therapeutic doses in the posterior segment. Different posterior segment diseases including age-related macular degeneration, diabetic macular edema, retinal vein occlusions, uveitis, and cystoid macular edema, among others, have been historically treated with intravitreal corticosteroids injections, and more recently with intravitreal corticosteroids drug implants. Triamcinolone acetonide (TA) is the most frequently used intraocular synthetic corticosteroid. Using nanoparticle-based TA delivery systems has been proposed as an alternative to intravitreal injections in the treatment of posterior segment diseases. From these novel delivery systems, topical liposomes have been the most promising strategy. This review is oriented to exhibit triamcinolone acetonide drug evolution and its results in treating posterior segment diseases using diverse delivery platforms.

Repurposing of parenterally administered active substances used to treat pain both systemically and locally

Pain is a constant in our lives. The efficacy of drug therapy administered by the parenteral route is often limited either by the physicochemical characteristics of the drug itself or its adsorption-distribution-metabolism-excretion (ADME) mechanisms. One promising alternative is the design of innovative drug delivery systems that can improve the pharmacokinetics |(PK) and/or reduce the toxicity of traditionally used drugs. In this review, we discuss several products that have been approved by the main regulatory agencies (i.e., nano- and microsystems, implants, and oil-based solutions), highlighting the newest technologies that govern both locally and systemically the delivery of drugs. Finally, we also discuss the risk assessment of the scale-up process required, given the impact that this approach could have on drug manufacturing. Teaser: The management of pain by way of the parenteral route can be improved using complex drug delivery systems (e.g., micro- and nanosystems) which require high-level assessment and shorten the regulatory pathway.

Treatment of Macular Edema in Vascular Retinal Diseases: A 2021 Update

Macular edema (ME) is associated with various conditions; however, the main causes of ME are retinal vein occlusion (RVO) and diabetes. Laser photocoagulation, formerly the gold standard for the treatment of ME, has been replaced by anti-vascular endothelial growth factor (anti-VEGF) intravitreal injections. Despite its efficiency, this treatment requires frequent injections to preserve the outcomes of anti-VEGF therapy, and as many patients do not sufficiently respond to the treatment, ME is typically a chronic condition that can lead to permanent visual impairment. Generalized recommendations for the treatment of ME are lacking, which highlights the importance of reviewing treatment approaches, including recent anti-VEGFs, intravitreal steroid implants, and subthreshold micropulse lasers. We reviewed relevant studies, emphasizing the articles published between 2019 and 2021 and using the following keywords: macular edema, diabetic macular edema, retinal vein occlusion, laser photocoagulation, anti-VEGF, and intravitreal injections. Our results revealed that a combination of different treatment methods may be beneficial in resistant cases. Additionally, artificial intelligence (AI) is likely to help select the best treatment option for patients in the near future.

Clinically established biodegradable long acting injectables: An industry perspective

Long acting injectable formulations have been developed to sustain the action of drugs in the body over desired periods of time. These delivery platforms have been utilized for both systemic and local drug delivery applications. This review gives an overview of long acting injectable systems that are currently in clinical use. These products are categorized in three different groups: biodegradable polymeric systems, including microparticles and implants; micro and nanocrystal suspensions and oil-based formulations. Furthermore, the applications of these drug delivery platforms for the management of various chronic diseases are summarized. Finally, this review addresses industrial challenges regarding the development of long acting injectable formulations.

Intravitreal steroids versus observation for macular edema secondary to central retinal vein occlusion

BACKGROUND

Central retinal vein occlusion (CRVO) is a common retinal vascular abnormality associated with conditions such as hypertension, diabetes, glaucoma, and a wide variety of hematologic disorders. Macular edema (ME) represents an important vision-threatening complication of CRVO. Intravitreal steroids (IVS), such as triamcinolone acetonide, have been utilized to treat macular edema stemming from a variety of etiologies and may be a treatment option for CRVO-ME.

OBJECTIVES

To explore the effectiveness and safety of intravitreal steroids in the treatment of CRVO-ME.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014 Issue 10), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to November 2014), EMBASE (January 1980 to November 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (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 13 November 2014. For all included primary studies, we used The Science Citation Index (3 December 2014) and manually reviewed reference lists to identify other possible relevant trials.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared intravitreal steroids, of any dosage and duration of treatment of at least six months, with observation for the treatment of CRVO-ME.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts identified from the electronic searches and assessed full-text articles from potentially eligible trials. Two review authors independently assessed trial characteristics, risk of bias, and extracted data from included trials. We contacted investigators of included trials for desired data not provided in the trial reports.

MAIN RESULTS

We included two RCTs that enrolled a total of 708 participants with CRVO-ME. SCORE compared triamcinolone acetonide intravitreal injections (n = 165) with observation (n = 72); GENEVA compared dexamethasone intravitreal implants (n = 290) with sham injections (n = 147). We observed characteristics indicative of high risk of bias due to incomplete outcome data in SCORE and selective outcome reporting in GENEVA. Loss to follow-up was high with 10% in the steroid groups and almost twice as much (17%) in the observation group. GENEVA enrolled participants with both branch and central retinal vein occlusion, but did not present subgroup data for the CRVO-ME population. A qualitative assessment of the results from GENEVA indicated that the dexamethasone implant was not associated with improvement in visual acuity after six months among participants with CRVO-ME. Although the SCORE investigators reported that participants treated with 1 mg (n = 82) or 4 mg (n = 83) triamcinolone intravitreal injections were five times more likely to have gained 15 letters or more in visual acuity compared with participants in the observation group (1 mg; risk ratio (RR): 5.27; 95% confidence interval (CI) 1.62 to 17.15; 4 mg RR 4.92; 95% CI 1.50 to 16.10) by the eighth-month follow-up examination, the average visual acuity decreased in all three groups. However, eyes treated with triamcinolone lost fewer letters than participants in the observation group at 8 months (1 mg mean difference (MD): 8.70 letters, 95% CI 1.86 to 15.54; 4 mg MD: 9.80 letters, 95% CI 3.32 to 16.28). A higher incidence of adverse events was noted with IVS therapy when compared with observation alone. As many as 20% to 35% of participants experienced an adverse event in the IVS groups compared with 8% of participants in the observation group of the SCORE study. The GENEVA investigators reported 63% in the treatment arm versus 43% in the observation arm experienced an adverse event. The most commonly encountered adverse events were elevated intraocular pressure, progression of cataracts, and retinal neovascularization. We graded the quality of evidence as low due to study limitations, imprecision of treatment estimates, and selective outcome reporting.

AUTHORS' CONCLUSIONS

The two RCTs reviewed herein provide insufficient evidence to determine the benefits of IVS for individuals with CRVO-ME. The improvement in visual acuity noted in the SCORE trial should be interpreted with caution as outcome data were missing for a large proportion of the observation group. Adverse events were observed more often with IVS treatment compared with observation/no treatment.

Preclinical safety evaluation of a recombinant AAV8 vector for X-linked retinoschisis after intravitreal administration in rabbits

X-linked retinoschisis (XLRS) is a retinal disease caused by mutations in the gene encoding the protein retinoschisin (RS1) and one of the most common causes of macular degeneration in young men. Currently, no FDA-approved treatments are available for XLRS and a replacement gene therapy could provide a promising strategy. We have developed a novel gene therapy approach for XLRS, based on the administration of AAV8-scRS/IRBPhRS, an adeno-associated viral vector coding the human RS1 protein, via the intravitreal route. On the basis of our prior study in an Rs1-KO mouse, this construct transduces efficiently all the retinal layers, resulting in an RS1 expression similar to that observed in the wild-type and improving retinal structure and function. In support of a clinical trial, we carried out a study to evaluate the ocular safety of intravitreal administration of AAV8-scRS/IRBPhRS into 39 New Zealand White rabbits. Two dose levels of vector, 2e(10) and 2e(11) vector genomes per eye (vg/eye), were tested and ocular inflammation was monitored over a 12-week period by serial ophthalmological and histopathological analysis. A mild ocular inflammatory reaction, consisting mainly of vitreous infiltrates, was observed within 4 weeks from injection, in both 2e(10) and 2e(11) vg/eye groups and was likely driven by the AAV8 capsid. At 12-week follow-up, ophthalmological examination revealed no clinical signs of vitreitis in either of the dose groups. However, while vitreous inflammatory infiltrate was significantly reduced in the 2e(10) vg/eye group at 12 weeks, some rabbits in the higher dose group still showed persistence of inflammatory cells, histologically. In conclusion, intravitreal administration of AAV8-scRS/IRBPhRS into the rabbit eye produces a mild and transient intraocular inflammation that resolves, at a 2e(10) vg/eye dose, within 3 months, and does not cause irreversible tissue damages. These data support the initiation of a clinical trial of intravitreal administration of AAV8-scRS/IRBPhRS in XLRS patients.

Acute retinal necrosis after intraocular triamcinolone acetonide injection

PURPOSE

The purpose of this study was to report a case of acute retinal necrosis after combined cataract surgery and intracameral triamcinolone acetonide injection in a healthy elderly patient.

METHODS

Testing used was a clinical examination including fundus photographs, fluo-rescein angiography, and serologic testing.

RESULTS

A 75-year-old healthy white woman undergoing cataract extraction received an injection of intracameral triamcinolone acetonide as a substitute for postoperative topical steroids. Two weeks later, the patient developed acute retinal necrosis, which responded well to systemic antiviral therapy.

CONCLUSION

Acute retinal necrosis is a rare, but potentially devastating, complication that may be associated with intraocular triamcinolone acetonide injection.

Intravitreal steroids for the treatment of retinal diseases

Diabetic macular edema (DME), pseudophakic cystoid macular edema (CME), age-related macular degeneration (AMD), retinal vascular occlusion (RVO), and uveitis are ocular conditions related to severe visual impairment worldwide. Corticosteroids have been widely used in the treatment of these retinal diseases, due to their well-known antiangiogenic, antiedematous, and anti-inflammatory properties. Intravitreal steroids have emerged as novel and essential tools in the ophthalmologist's armamentarium, allowing for maximization of drug efficacy and limited risk of systemic side effects. Recent advances in ocular drug delivery methods led to the development of intraocular implants, which help to provide prolonged treatment with controlled drug release. Moreover, they may add some potential advantages over traditional intraocular injections by delivering certain rates of drug directly to the site of action, amplifying the drug's half-life, contributing in the minimization of peak plasma levels of the drug, and avoiding the side effects associated with repeated intravitreal injections. The purpose of this review is to provide an update on the use of intravitreal steroids as a treatment option for a variety of retinal diseases and to review the current literature considering their properties, safety, and adverse events.

Intravitreal injection of triamcinolone acetonide into healthy rabbit eyes alters retinal function and morphology

AIM

To study the effects of intravitreally injected triamcinolone acetonide (TA) and/or its preservative benzyl alcohol (BA) in healthy rabbit retina.

METHODS

Forty-eight rabbits (aged 4 months, body weight ≈3 kg) were randomized into four groups (n = 12). They were examined with electroretinography (ERG) prior to drug exposure, and then injected intravitreally with a combination of TA and BA, TA without BA, BA alone or a balanced saline solution (BSS). The electroretinograms were assessed 1 week and 7 weeks post-injection. The rabbits were euthanized and the sectioned retinas were studied. Immunohistochemical analysis was performed on rods, cones, rod bipolar cells, horizontal cells, amacrine cells and Müller cells.

RESULTS

Rabbits injected with BA showed a significantly lower rod-mediated b-wave amplitude than the controls 1 week after injection. TA-injected rabbits demonstrated significantly higher a- and b-wave amplitudes in the total retinal response than the controls 1 week post-injection. The rabbits injected with TA + BA demonstrated a significantly higher b-wave amplitude in the total retinal response than the controls 1 week after injection. The significantly higher a-wave amplitude in the total retinal response remained in the TA-injected rabbits 7 weeks after injection. Immunohistochemistry revealed that protein kinase C alpha (PKC α) was down-regulated in both the perikarya and the axons of bipolar cells in histological sections from rabbit retina injected with TA + BA, BA and TA.

CONCLUSIONS

Intravitreal injection of the preservative BA reduces the isolated rod-mediated retinal response in the rabbit, transiently and selectively. Intravitreal injection of TA increases the total retinal response in the rabbit up to seven weeks after injection. The effects observed are not only limited to retinal function, but also include changes in the expression of PKC α in rod bipolar cells, indicating drug-related interference with normal retinal physiology in the healthy rabbit eye.

Hypothalamic-pituitary-adrenal axis function following intravitreal triamcinolone acetonide injection

To evaluate the pituitary-adrenal axis function by means of the adrenocorticotropic hormone (ACTH) stimulation test following a single intravitreal injection of triamcinolone acetonide (IVTA). Prospective comparative clinical interventional study. Twenty-eight patients (28 eyes) received a single IVTA (4 mg in 0.1 ml) for macular edema. The basal cortisol level and the response to 1 μg adrenocorticotropic hormone stimulation were determined on the morning before IVTA injection and at 1 day and 1, 2, and 4 weeks after IVTA injection. Results were compared with those obtained from a control group of 50 healthy subjects. All patients in the study had normal basal cortisol and normal response to ACTH challenge before receiving IVTA. 1 day following IVTA, basal cortisol was suppressed in one patient in the study group. Fasting serum cortisol levels at 1, 2, and 4 weeks after IVTA injection were normal in all patients in the study group. 1 day following IVTA, the peak response to ACTH at 30 min was blunted in four patients (14.3 % of the study group, p = 0.05) and the cortisol response at 60 min was suppressed (p = 0.009). 1 week following IVTA, the response to ACTH challenge was blunted in only one patient. A single IVTA injection may be associated with impaired hypothalamic-pituitary-adrenal function in some patients during the first 24 h following IVTA.

Drug safety evaluation of intravitreal triamcinolone acetonide

INTRODUCTION

Triamcinolone acetonide (TA) is a steroidal drug that has been widely administered intravitreally for retinal and choroidal conditions. Safety of steroidal products for intraocular use is essential because of their risk of ocular adverse events. This review comprehensively discusses the safety of intravitreal administration of TA.

AREAS COVERED

This paper analyzes the mechanisms of action and key pharmacokinetic attributes and provides a discussion of the main clinical trials investigating clinical applications of intravitreal TA. The safety of intravitreal TA is evaluated through a search of the Medline database from 1980 to 2011. The most relevant literature on the safety of intravitreal TA is also discussed.

EXPERT OPINION

The complications of intravitreal TA therapy include secondary ocular hypertension in about 20 - 40% of eyes, steroid-induced cataract in about 15 - 20% of cases and postinjection infectious endophthalmitis and pseudoendophthalmitis in less than 1%. TA is an effective drug for various retinal and choroidal diseases when delivered intravitreally. It may imply an off-label use and it may be associated with ocular adverse events. Intravitreal TA is not associated with significant systemic safety risks.

Functional and structural effect of intravitreal indocyanine green, triamcinolone acetonide, trypan blue, and brilliant blue g on rat retina

PURPOSE

The purpose of this study was to evaluate the functional and structural damage of the retina after intravitreal injections of four different dyes in the rat.

METHODS

Rats were injected intravitreally with indocyanine green (ICG), trypan blue, triamcinolone acetonide, or brilliant blue G in the right eye. The other eye was injected with saline and served as a control. Simultaneous bilateral electroretinograms were recorded before injection and 7 and 28 days after injection. Histology and immunohistochemistry analyses with antibodies recognizing glial fibrillary acidic protein and protein kinase C were performed 28 days after the initial injection on both eyes.

RESULTS

Seven days after dye injection, the electroretinogram response of the treated eyes was altered in each group. At 1 month, eyes injected with triamcinolone acetonide, trypan blue, or brilliant blue G fully recovered, whereas eyes treated with ICG had A-wave and B-wave reduction of 65% and 63%, respectively. The inner nuclear layer thickness was statistically decreased in the ICG group (P = 0.003) but not with other dyes. Protein kinase C staining was decreased in the ICG group only, but no abnormal qualitative staining was found with either glial fibrillary acidic protein or protein kinase C antibodies with any dye.

CONCLUSION

Among the four tested dyes, only ICG led to functional and structural retinal damage.

Photodynamic therapy with or without intravitreal triamcinolone acetonide for symptomatic polypoidal choroidal vasculopathy

PURPOSE

To evaluate the outcome of verteporfin photodynamic therapy (PDT) with or without intravitreal triamcinolone acetonide (IVTA) for the treatment of symptomatic polypoidal choroidal vasculopathy (PCV).

METHODS

Retrospective analysis of PCV patients who underwent PDT with or without IVTA with follow-up of 2 or more years. Changes in best-corrected visual acuity (BCVA), proportion of eyes with moderate visual loss (3 or more lines), and complications were compared between patients with or without IVTA.

RESULTS

Twenty-seven eyes of 27 patients were analyzed, with 12 eyes treated by PDT monotherapy and 15 eyes treated by combined PDT with IVTA. The baseline characteristics of both groups were similar. At 1 year, the mean logMAR BCVA for the PDT monotherapy group improved from 0.74 to 0.58 (P = 0.011), whereas the combined PDT and IVTA group improved from 0.84 to 0.74 (P = 0.17). At 2 years, the mean logMAR BCVA for the monotherapy and combined treatment groups were 0.62 and 0.84, respectively, and the changes compared with baseline were not statistically significant. No significant difference was found in the mean logMAR BCVA, the mean line of visual changes, and the mean number of PDT treatments between the 2 groups at 1 and 2 years. One (8.3%) and 4 (26.7%) eyes in the monotherapy and the combined groups lost 3 or more lines at 2 years, respectively. Patients who had combined PDT with IVTA were more likely to develop cataract requiring surgery and ocular hypertension (P = 0.043 and 0.046, respectively).

CONCLUSIONS

PDT reduced the risks of visual loss in patients with symptomatic PCV in the short term but the effect might not be sustained after 1 year. The adjunctive use of IVTA during PDT did not appear to result in additional benefit for treating PCV.

Complications of intravitreal injections

PURPOSE OF REVIEW

Over the past few years, the results of many studies have highlighted the risks and benefits of intravitreal injection of a number of medications, the most common being triamcinolone, antivascular endothelial growth factor (VEGF) agents, antibiotics, antivirals, antifungals, and methotrexate. The purpose of this review is to highlight the complications associated with these injections.

RECENT FINDINGS

Elevated intraocular pressure and glaucoma are the most common complications of intraocular triamcinolone. There is also an increased incidence of cataract formation/progression over time. The immunosuppressive effect of triamcinolone does not appear to increase the risk of endophthalmitis. Recent reports suggest that intravitreal anti-VEGF injections have a low complication rate. Similarly, antimicrobials also have low rates of injection-associated complications.

SUMMARY

Intravitreal injections play a critical role in daily ophthalmic practice. The overall risk of endophthalmitis and retinal detachment appears to be low and most of the commonly used drugs are well tolerated, even with repeat injection. Further long-term studies need to be performed to elucidate ways of increasing the safety of these procedures and medications.

[Effectiveness of interferon alpha in the treatment of uveitis macular edema refractory to corticosteroid and/or immunosuppressive treatment]

INTRODUCTION

Macular edema is always a major complication in intermediate and/or posterior uveitis. Some of these macular edemas are refractory to steroid and/or immunosuppressive drugs. Interferon, a validated treatment for Behçet disease, has antiproliferative and immunoregulative properties that may be very valuable in uveitic edema refractory to steroid and/or immunosuppressive agents. Recent studies have brought out the value of interferon-alpha by demonstrating its low blood rate in affected patients.

OBSERVATIONS

We describe a series of six consecutive uveitic macular edema, secondary to two birdshot retinochoroidopathy, and four cases of idiopathic uveitis treated with interferon-alpha. Our small case series showed a 189.7+/-67 mum decrease in mapping and an improvement in visual acuity of 0.35+/-0.21 LogMAR.

DISCUSSION

Other publications have shown a remarkable efficacy on macular edema and visual acuity in less than 1 month of treatment. Our small case series found the same results as the other studies, despite a less aggressive therapeutic regimen. However, we also observed some well-known side effects, in particular depression.

CONCLUSION

In our series of six consecutive cases of uveitic macular edema refractory to steroid or immunosuppressive drugs, alpha-interferon provided highly advantageous anatomical and functional results. The treatment modality must be specified, but it seems that a shorter duration and lower posologies might be as effective and lead to a lower rate of complications than the regimen currently proposed in the literature.

Blood-assisted internal limiting membrane peeling for macular hole repair

PURPOSE

To evaluate the efficacy of autologous heparinized whole blood in assisting internal limiting membrane (ILM) peeling by coating the ILM for macular hole (MH) repair.

DESIGN

Prospective, interventional case series.

PARTICIPANTS

Twenty-nine patients (32 eyes) who underwent blood-assisted ILM peeling for MH repair.

METHODS

Patients in whom stage 2-4 idiopathic MHs had developed and who desired surgery were enrolled in this study. After core vitrectomy, autologous heparinized whole blood was applied to cover the macula and to coat the surface of the macular area in the fluid-filled vitreous cavity. The redundant blood was removed and only a very thin film of blood was left on the macular area. The blood-coated ILM was removed by forceps in a circular fashion. To confirm the removed membrane was the ILM, the first 10 specimens were examined by electron microscopy (EM).

MAIN OUTCOME MEASURES

The MH closure rate, the interval mean visual acuity (before and after surgery), retinal changes, and the EM results of the ILM specimens.

RESULTS

All 32 eyes in 29 patients completed 12 months of follow-up. The ILM were coated by autologous heparinized whole blood, removed without difficulty, and confirmed by EM. The whole blood highlighted the contrast of the coated and noncoated areas during the ILM peeling procedure. The MHs were closed in all surgical eyes with a single surgery (100%). Compared with study entry, the mean logMAR best-corrected visual acuity 12 months after surgery improved significantly (1.02 and 0.53, respectively; P<0.001). At 12 months of follow-up, 31 eyes (96.9%) had stable or improved vision. No toxic fundus changes were observed during follow-up.

CONCLUSIONS

Autologous heparinized whole blood coated the ILM and facilitated visibility during ILM peeling. Autologous heparinized whole blood is a cost-effective and useful tool for assisting MH surgery.

Intravitreal steroids versus observation for macular edema secondary to central retinal vein occlusion

BACKGROUND

Central retinal vein occlusion (CRVO) is a common retinal vascular abnormality associated with conditions such as hypertension, diabetes, glaucoma, and a wide variety of hematologic disorders. Macular edema (ME) represents an important vision-threatening complication of CRVO. There is no proven treatment; laser photocoagulation is not effective in treating cystoid macular edema secondary to CRVO. Intravitreal steroids, such as triamcinolone acetonide, have been utilized to treat macular edema stemming from a variety of etiologies and may represent a treatment option for CRVO-ME.

OBJECTIVES

The objective of this review was to explore the effectiveness and safety of intravitreal steroids in the treatment of CRVO-ME.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 4, 2008), MEDLINE (January 1950 to November 2008) and EMBASE (January 1980 to November 2008). There were no language or date restrictions in the search for trials. The electronic databases were last searched on 5 November 2008. For all included primary studies, we used The Science Citation Index and manually reviewed reference lists to identify other possible relevant trials. We contacted researchers in the field, currently working on a randomized controlled trial (RCT) on this topic (The Standard Care versus Corticosteroid for Retinal Vein Occlusion - SCORE study), for information on additional current, past, or unpublished trials.

SELECTION CRITERIA

We considered RCTs that compared intravitreal steroids of any dosage/duration to observation in the treatment of CRVO-ME for inclusion in this review. We focused on studies that included individuals of any age or gender with unilateral or bilateral disease, with a minimum of six months follow up. Secondarily we considered non-randomized studies with the same criteria for description of evidence, however we did not conduct a separate electronic search for finding all non-randomized studies.

DATA COLLECTION AND ANALYSIS

We found no RCTs that met the inclusion criteria after independent and duplicate review of the search results.

MAIN RESULTS

We found no relevant RCTs and therefore performed no meta-analysis. Evidence from non-randomized studies is reported in this review.

AUTHORS' CONCLUSIONS

There is inadequate evidence for the use of intravitreal steroids for CRVO-ME due to a paucity of RCTs and well-designed observational studies on the topic; therefore, it is still an experimental procedure.

Testing retinal toxicity of drugs in animal models using electrophysiological and morphological techniques

Drugs are frequently tested for retinal toxicity in animal models in order to address applied and basic research questions. When a retinal toxicity study is designed, the researcher needs to consider several factors depending on his/her research questions. Among the factors that need to be addressed before a toxicity study is conducted are: the animal species to be used, choice of experimental (functional and/or morphological) techniques, procedure of testing, period of follow-up, and modes of data analysis. This review is a summary of 20 years' experience of studying retinal toxicity of different drugs in rabbits and rats. The use of the electroretinogram and the visual evoked potential for assessment of outer and inner retinal function, respectively, is described as well as the use of morphological techniques (histology, histochemistry, and immunocytochemistry). The advantages and limitations of functional and morphological techniques are discussed with specific examples from my experience. Recommendations for future drug toxicity studies are summarized.

Intravitreal triamcinolone for diabetic macular edema: comparison of 1, 2, and 4 mg

PURPOSE

To compare the efficacy and safety of different doses of intravitreal triamcinolone (IVTA) in treating eyes with refractory diffuse diabetic macular edema (DME) with cystic changes.

METHODS

Forty-five eyes of 45 patients with diffuse DME were randomized to receive 1, 2, or 4 mg IVTA. Patients were observed for 6 months and changes in best-corrected visual acuity (VA) in Early Treatment Diabetic Retinopathy Study (ETDRS) scores, retinal thickness analyzer (RTA) central macular thickness (CMT), intraocular pressure, and cataract progression were compared among the three groups.

RESULTS

Forty-two patients completed 6 months of follow-up and were included in the analysis. Following IVTA injection, the ETDRS score improved similarly, eight to nine letters, in all three groups at 4 weeks. The standardized CMT improved in all three groups at 4 weeks. This improvement was maintained through 12 and 24 weeks in the 1 and 2 mg groups, but not in the 4 mg group, which was significantly worse than the 1 and 2 mg groups at 12 and 24 weeks (P = 0.01, 0.03, 0.01, and 0.05).

CONCLUSIONS

Regarding eyes with refractory diffuse DME with cystic changes, 4 mg IVTA does not appear to be more effective than 1 or 2 mg IVTA.