Intravitreal Ziv-Aflibercept in Patients With Diabetic Macular Edema Refractory to Intravitreal Bevacizumab

BACKGROUND AND OBJECTIVE

To evaluate the efficacy of intravitreal ziv-aflibercept (IVZ) in patients with diabetic macular edema (DME) resistant to intravitreal bevacizumab (IVB).

PATIENTS AND METHODS

This prospective study was conducted in patients with persistent DME. Patients were switched to IVZ no longer than 6 weeks after the last three consecutive monthly IVB treatments and monitored over a course of 12 weeks. Changes in best-corrected visual acuity (BCVA), central macular thickness (CMT), and macular volume on optical coherence tomography were compared.

RESULTS

A total of 59 eyes (38 patients) were included. Mean BCVA improved from 0.84 to 0.71 logMAR (P = .001) after first IVZ treatment and remained significant. In a subgroup analysis, this significance was observed only in the group with baseline visual acuity of less than 20/50. Mean CMT decreased from 479 μm to 364 μm (P = .004) after the first IVZ injections and remained significant.

CONCLUSION

IVZ may be best reserved for patients with persistent DME after initial failure with bevacizumab, with less likelihood for anatomic or functional improvement in those with mild persistent DME. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:145-151.].

Erratum: Retinal image mosaicking using scale-invariant feature transformation feature descriptors and Voronoi diagram (Erratum)

[This corrects the article DOI: 10.1117/1.JMI.7.4.044001.].

Retinal image mosaicking using scale-invariant feature transformation feature descriptors and Voronoi diagram

Purpose: Peripheral retinal lesions substantially increase the risk of diabetic retinopathy and retinopathy of prematurity. The peripheral changes can be visualized in wide field imaging, which is obtained by combining multiple images with an overlapping field of view using mosaicking methods. However, a robust and accurate registration of mosaicking techniques for normal angle fundus cameras is still a challenge due to the random selection of matching points and execution time. We propose a method of retinal image mosaicking based on scale-invariant feature transformation (SIFT) feature descriptor and Voronoi diagram. Approach: In our method, the SIFT algorithm is used to describe local features in the input images. Then the input images are subdivided into regions based on the Voronoi method. Each pair of Voronoi regions is matched by the method zero mean normalized cross correlation. After matching, the retinal images are mapped into the same coordinate system to form a mosaic image. The success rate and the mean registration error (RE) of our method were compared with those of other state-of-the-art methods for the P category of the fundus image registration database. Results: Experimental results show that the proposed method accurately registered 42% of retinal image pairs with a mean RE of 3.040 pixels, while a lower success rate was observed in the other four state-of-the-art retinal image registration methods GDB-ICP (33%), Harris-PIIFD (0%), HM-2016 (0%), and HM-2017 (2%). Conclusions: The proposed method outperforms state-of-the-art methods in terms of quality and running time and reduces the computational complexity.

Intravitreal Injection of Anti-vascular Endothelial Growth Factor Agents for Ocular Vascular Diseases: Clinical Practice Guideline

PURPOSE

To provide the clinical recommendations for the administration of intravitreal anti-vascular endothelial growth factor (VEGF) drugs especially bavacizumab for ocular vascular diseases including diabetic macular edema, neovascular age-related macular degeneration, myopic choroidal neovascularization, retinal vein occlusion and central serous chorioretinopathy.

METHODS

Twenty clinical questions were developed by the guideline technical committee. Relevant websites and databases were searched to find out the pertinent clinical practice guidelines to answer the questions. The technical committee provided possible answers (scenarios) according to the available evidences for each question. All scenarios along with their levels of evidence and the supported articles were sent to the experts for external review. If the experts did not agree on any of the scenarios for one particular clinical question, the technical committee reviewed all scenarios and their pertinent evidences and made the necessary decision. After that, the experts were asked to score them again. All confirmed scenarios were gathered as the final recommendations.

RESULTS

All the experts agreed on at least one of the scenarios. The technical committee extracted the agreed scenario for each clinical question as the final recommendation. Finally, 56 recommendations were developed for the procedure of intravitreal anti-VEGF injection and their applications in the management of ocular vascular diseases.

CONCLUSION

The implementation of this guideline can standardize the management of the common ocular vascular diseases by intravitreal injection of anti-VEGF agents. It can lead to better policy-making and evidence-based clinical decision by ophthalmologists and optimal evidence based eye care for patients.

Comparison of Intravitreal Bevacizumab and Laser Photocoagulation in the Treatment of Retinopathy of Prematurity

PURPOSE

To compare the outcomes of patients with type I retinopathy of prematurity (ROP) treated with either intravitreal bevacizumab (IVB) or retinal laser photocoagulation (RLP).

DESIGN

Retrospective case series.

PARTICIPANTS

Infants treated for type I ROP with IVB or RLP.

METHODS

Patients who were born between January 2011 and December 2014 and were treated in Farabi Eye Hospital were included. The outcomes were stratified and analyzed, based on the treatment type and ROP zone.

MAIN OUTCOME MEASURES

Need for retreatment, time to regression, refractive errors, retinal adverse anatomic outcomes, and rate of complications.

RESULTS

Five hundred twenty-three patients were treated for type 1 ROP, of whom 493 (986 eyes) met inclusion criteria. Seven hundred twenty-four eyes (73.4%) received IVB, and 262 eyes (26.5%) received RLP. Re-treatment (because of recurrent or persistent retinopathy) occurred in 14.4% (106/724) of eyes initially treated with IVB and in 8.8% (23/262) eyes initially treated with RLP (P = 0.065). Re-treatment was not significantly different between the 2 groups for patients with zone I disease (P = 0.978). Re-treatment rate was considerably higher in patients with zone II disease treated with IVB (69/558 [12.3%]) compared with those treated with RLP (20/251 [7.9%]; P = 0.017). In the IVB group, 82.8% and 53.4% of eyes showed an avascular area in zone III (despite ROP regression) at 1 and 2 years after treatment, respectively. The spherical power and the spherical equivalent were significantly higher in eyes treated with RLP (-1.31±2.83 diopters [D] and -2.84±2.77 D, respectively) than eyes treated with IVB (0.19±3.21 D and -1.26±3.19 D, respectively; P = 0.016 and P = 0.007, respectively). Differences in astigmatic power were not significant.

CONCLUSIONS

Both IVB and RLP are effective treatments for type 1 ROP. Longer follow-up time is necessary for infants treated with IVB. More patients with zone II disease treated with RLP achieved disease regression after a single treatment than those who received IVB, although outcomes after re-treatment were comparable except for a greater refractive error in patients treated with RLP.

Single-Session Photodynamic Therapy Combined with Intravitreal Bevacizumab for Neovascular Age-Related Macular Degeneration

Purpose

To evaluate the efficacy of combined single-session photodynamic therapy (PDT) and intravitreal bevacizumab (IVB) for treatment of neovascular age-related macular degeneration (AMD).

Methods

In a prospective interventional case series, patients with subfoveal choroidal neovascularization (CNV) underwent PDT followed by 1.25 mg IVB injection. Best-corrected visual acuity (BCVA) and optical coherence tomography (OCT) measurements were repeated at 6-week intervals and fluorescein angiography was performed after 12 weeks and when considered necessary thereafter. Repeat injections of IVB were performed based on fluorescein angiographic evidence of CNV leakage.

Results

Fourteen eyes were included in this study. Mean follow-up was 52.4±15.2 weeks (range: 26–74 weeks). Initially, mean BCVA was 0.80±0.42 logMAR and mean central macular thickness (CMT) was 308±88 μm. At week 12, BCVA improved to 0.62±0.47 logMAR (p=0.006) and CMT reduced to 186±53 μm (p=0.003). Corresponding results were 0.53±0.52 logMAR (p=0.02) and 193±78 μm (p=0.002) after 24 weeks. A second IVB injection was performed in 13 eyes with a mean interval of 16.3±5.9 weeks.

Conclusions

Combination therapy with single-session PDT and IVB can improve vision and reduce CMT in neovascular AMD. Repeat IVB injections may maintain the visual gain from the initial combination therapy.

Efficacy of Intravitreal Bevacizumab for the Treatment of Zone I Type 1 Retinopathy of Prematurity

Purpose

To describe the efficacy of intravitreal bevacizumab for the treatment of type 1 retinopathy of prematurity (ROP) in zone I.

Methods

Preterm infants with type 1 ROP in zone I (zone I ROP, any stage with plus disease or zone I ROP, stage 3 without plus disease) were enrolled in this prospective study. Intravitreal bevacizumab (0.625 mg/0.025 ml) was injected under topical anesthesia. Patients were followed weekly for 4 weeks and then biweekly till 90 weeks gestational age.

Results

Seventy eyes of 35 patients with type 1 ROP in zone I were enrolled. At a gestational age of 90 weeks, ROP regressed with complete or near-complete peripheral retinal vascularization, in 82.9% of eyes after a single injection and in 92.9% of eyes after up to two injections. In five eyes (7.1%), ROP progressed to stage 4B or 5, so surgical management was required. There were no major complications such as endophthalmitis, cataract, or vitreous hemorrhage after injection.

Conclusion

Intravitreal bevacizumab injection is an effective method for the management of patients with Zone I ROP requiring treatment; however, some cases may progress to more advanced stages and require surgical management. Close monitoring for recurrence or progression is necessary. Eyes with persistent zone I ROP may progress to advanced stages when treated with intravitreal bevacizumab injection and re-treatment may be needed.

The Role of Mitochondria in AMD: Current Knowledge and Future Applications

Mitochondria are organelles which comprise the main respiratory machinery in the eukaryotic cells. In addition to their crucial role in energy production, they have profound effects on apoptosis and retrograde signaling to nucleus. Mitochondria have their own DNA, which codes for different proteins mostly involved in oxidative phosphorylation. Significant changes in the mitochondria of retinal pigment epithelium have been reported in age-related macular degeneration (AMD), which is correlated with the severity of the disease. Cybrid cell lines that have identical nuclei but mitochondria from different individuals can provide a unique means for studying the relationship between mitochondria and AMD. Different approaches for protection of mitochondria have been introduced which can be considered as potential future treatments for AMD and other age- related disorders.

Effects of Benzo(e)pyrene on Reactive Oxygen/Nitrogen Species and Inflammatory Cytokines Induction in Human RPE Cells and Attenuation by Mitochondrial-involved Mechanism

Purpose:

To identify inhibitors that could effectively lower reactive oxygen/nitrogen species (ROS/RNS), complement and inflammatory cytokine levels induced by Benzo(e)pyrene [B(e)p], an element of cigarette smoke, in human retinal pigment epithelial cells (ARPE-19) in vitro.

Methods:

ARPE-19 cells were treated for 24 hours with 200 μM, 100 μM, and 50 μM B(e)p or DMSO (dimethyl sulfoxide)-equivalent concentrations. Some cultures were pre-treated with ROS/RNS inhibitors (NG nitro-L-arginine, inhibits nitric oxide synthase; Apocynin, inhibits NADPH oxidase; Rotenone, inhibits mitochondrial complex I; Antimycin A, inhibits mitochondria complex III) and ROS/RNS levels were measured with a fluorescent H₂ DCFDA assay. Multiplex bead arrays were used to measure levels of Interleukin-6 (IL-6), Interleukin-8 (IL-8), Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF), Transforming Growth Factor alpha (TGF-α) and Vascular Endothelial Growth Factor (VEGF). IL-6 levels were also measured by an enzyme-linked immunosorbent assay. Real-time qPCR analyses were performed with primers for C3 (component 3), CFH (inhibits complement activation), CD59 (inhibitor of the complement membrane attack complex (MAC)) and CD55/DAF (accelerates decay of target complement target proteins).

Results:

The ARPE-19 cultures treated with B(e)p showed significantly increased ROS/RNS levels (P < 0.001), which were then partially reversed by 6 μM Antimycin A (19%, P = 0.03), but not affected by the other ROS/RNS inhibitors. The B(e)p treated cultures demonstrated increased levels of IL-6 (33%; P = 0.016) and GM-CSF (29%; P = 0.0001) compared to DMSO-equivalent controls, while the expression levels for components of the complement pathway (C3, CFH, CD59 and CD55/DAF) were not changed.

Conclusion:

The cytotoxic effects of B(e)p include elevated ROS/RNS levels along with pro-inflammatory IL-6 and GM-CSF proteins. Blocking the Qi site of cytochrome c reductase (complex III) with Antimycin A led to partial reduction in B(e)p induced ROS production. Our findings suggest that inhibitors for multiple pathways would be necessary to protect the retinal cells from B(e)p induced toxicity.

Predictive Value of Pupillary Response to Mydriatic Agents for Diagnosis of Retinopathy of Prematurity

Purpose:

To evaluate the feasibility of screening for retinopathy of prematurity (ROP) by assessing the pupillary response to mydriatics.

Methods:

This observational case series included 134 eyes of 67 premature infants with birth weight less than 2,000 grams and gestational age less than 33 weeks. A composite eye drop composed of phenylephrine 1%, tetracaine and tropicamide 0.5% was applied 3 times within 5-minute intervals and pupil diameters were measured. The eyes were examined by experienced ROP specialists using an indirect ophthalmoscope. Zone and stage of ROP, presence of plus disease and need for treatment were recorded. The relationship between the pupillary response to mydriatics, and presence and severity of ROP was evaluated. Logistic regression was used for statistical analysis.

Results:

According to receiver operating characteristic (ROC) curve analysis, final pupil diameter after mydriatic administration was found the most accurate factor among other factors to recognize ROP zone I from zones II and III (Area under ROC: 0.92 [95%CI: 0.85-0.98]). The best cutoff value for final pupil diameter was 5.6 mm, because it could differentiate involvement of zone I from zones II and III with sensitivity of 80% and specificity of 100%.

Conclusion:

Response of the pupil to mydriatic eye drops may be useful as a less invasive method for rough estimation of ROP in high risk babies who need emergent attention; however, it cannot be considered as a screening test due to its low sensitivity.

Macular Surgery Using Intraoperative Spectral Domain Optical Coherence Tomography

PURPOSE

To report the use of intraoperative spectral domain optical coherence tomography (SD-OCT) for detecting anatomical changes during macular surgery.

METHODS

In a consecutive case series, 32 eyes of 32 patients undergoing concurrent pars plana vitrectomy and intraoperative SD-OCT for macular hole (MH), epiretinal membrane (ERM) and vitreomacular traction (VMT) were enrolled. Intraoperative changes in retinal thickness and dimensions of the macular hole were measured in patients with ERM and VMT following surgical manipulation using a hand-held SD-OCT device (iVue, Optovue Inc., Fremont, CA, USA).

RESULTS

SD-OCT images of sixteen eyes with macular hole were subjected to quantitative and qualitative analysis. All MH dimensions remained stable during consecutive stages of surgery except for MH apex diameter, which showed a significant decrease after internal limiting membrane (ILM) peeling (P=0.025). Quantitative analysis of ten patients with ERM showed a significant decrease in retinal thickness after membrane removal (P=0.018) which did not remain significant until the end of the procedure (P=0.8). In three cases, subretinal fluid was formed after ILM peeling. Quantitative analysis of five patients with VMT showed a decrease in retinal thickness during consecutive steps of the surgery, although these changes were not significant. In two cases, subretinal fluid was formed after ILM peeling.

CONCLUSION

Intraoperative SD-OCT is a useful imaging technique which provides vitreoretinal surgeons with rapid awareness of changes in macular anatomy during surgery and may therefore result in better anatomical and visual outcomes.

Diabetic Retinopathy Clinical Practice Guidelines: Customized for Iranian Population

Purpose:

To customize clinical practice guidelines (CPGs) for management of diabetic retinopathy (DR) in the Iranian population.

Methods:

Three DR CPGs (The Royal College of Ophthalmologists 2013, American Academy of Ophthalmology [Preferred Practice Pattern 2012], and Australian Diabetes Society 2008) were selected from the literature using the AGREE tool. Clinical questions were designed and summarized into four tables by the customization team. The components of the clinical questions along with pertinent recommendations extracted from the above-mentioned CPGs; details of the supporting articles and their levels of evidence; clinical recommendations considering clinical benefits, cost and side effects; and revised recommendations based on customization capability (applicability, acceptability, external validity) were recorded in 4 tables, respectively. Customized recommendations were sent to the faculty members of all universities across the country to score the recommendations from 1 to 9.

Results:

Agreed recommendations were accepted as the final recommendations while the non-agreed ones were approved after revision. Eventually, 29 customized recommendations under three major categories consisting of screening, diagnosis and treatment of DR were developed along with their sources and levels of evidence.

Conclusion:

This customized CPGs for management of DR can be used to standardize the referral pathway, diagnosis and treatment of patients with diabetic retinopathy.

Multifocal Electroretinogram in Diabetic Macular Edema; Correlation with Visual Acuity and Optical Coherence Tomography

Purpose:

To evaluate multifocal electroretinogram (mfERG) changes in eyes with diabetic macular edema (DME) and investigate any possible correlation with optical coherence tomography (OCT) features and visual acuity (VA).

Methods:

Twenty-nine right eyes of 29 subjects with DME due to non-proliferative diabetic retinopathy and 30 eyes of 30 normal subjects were evaluated. All patients underwent a complete ophthalmic examination. Sixty-one scaled hexagon mfERG responses were recorded. Components of the first order kernel of N1, N2, and P1 in five concentric rings centered on the fovea, were measured in both groups. Correlation and regression analyses were performed among VA, central macular thickness (CMT) based on OCT, mfERG amplitude, and latency of the N1, N2 and P1 waves.

Results:

Significant differences were observed in all mfERG parameters in five-ring regions of the retina between eyes with DME versus controls (P < 0.05). There were significant correlations among VA with N2 (P = 0,001, b = 0.73) and P1 amplitudes (P = 0.001, b = −0.84) in the central macular area, and there was a borderline association between VA and CMT (P = 0.042, b = 0.392).

Conclusion:

Amplitudes of mfERG components (N1, P1, and N2) are significantly reduced and their latencies are delayed in eyes with DME indicating functional impairment in the outer retina. The mfERG total amplitude was significantly correlated with VA even more than CMT, therefore the combined use of OCT and mfERG for macular evaluation may better evaluate visual status in DME patients.

Thermoanalytical characterization of clindamycin-loaded intravitreal implants prepared by hot melt extrusion

BACKGROUND

The aim of the present study was to evaluate a non-destructive fabrication method in for the development of sustained-release poly (L, D-lactic acid)-based biodegradable clindamycin phosphate implants for the treatment of ocular toxoplasmosis.

MATERIALS AND METHODS

The rod-shaped intravitreal implants with an average length of 5 mm and a diameter of 0.4 mm were evaluated for their physicochemical parameters. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR), and nuclear magnetic resonance (1H NMR) studies were employed in order to study the characteristics of these formulations.

RESULTS

Drug content uniformity test confirmed the uniformity in different implant batches. Furthermore, the DSC, FTIR, and 1H NMR studies proved that the fabrication process did not have any destructive effects either on the drug or on the polymer structures.

CONCLUSION

These studies showed that the developed sustained-release implants could be of interest for long-term sustained intraocular delivery of clindamycin, which can provide better patient compliance and also have good potential in terms of industrial feasibility.

Albuminated PLGA nanoparticles containing bevacizumab intended for ocular neovascularization treatment

Bevacizumab, an anti-VEGF antibody, has demonstrated trustworthy effects in treatment of retinal and choroidal neovascularization that both are crucial sight threatening conditions. However, the weak point is the short half-life of the drug in vitreous which necessitates frequent intravitreal injections. Accordingly employing controlled-release drug delivery systems such as polymeric nanoparticles (NPs) has been suggested. In this study albuminated-PLGA-NPs containing bevacizumab were prepared and studied intended for reducing the number of injections. NPs were formulated by double-emulsion method and a single dose of NPs was intravitreally injected to rabbits. The drug concentrations in vitreous and aqueous humor were assayed in different time intervals using ELISA and intraocular pharmacokinetic parameters were calculated. Moreover, coumarin-6 loaded albuminated-PLGA-NPs were employed to evaluate the distribution and persistence of the NPs in the posterior segment. Results revealed that the bevacizumab vitreous concentration maintained above 500 ng mL(-1) for about 8 weeks and 3.3 times elevation was observed in the drug vitreous MRT compared with the control. According to coumarin-6 NP tests, fluorescence emissions in posterior tissues were observed for 56 days which confirmed the nanoparticles persistence in ocular tissues during the test span. Therefore our prepared formulation may offer improvements in treatment of eye posterior segment neovascularization.

Photodynamic Therapy and Intravitreal Bevacizumab with Versus without Triamcinolone for Neovascular Age-related Macular Degeneration; a Randomized Clinical Trial

PURPOSE

To compare the outcomes of photodynamic therapy (PDT) combined with intravitreal bevacizumab (IVB) with versus without intravitreal triamcinolone (IVT) in neovascular age-related macular degeneration (AMD).

METHODS

Eighty-four eyes with active CNV secondary to AMD with no prior treatment were enrolled and followed for 1-year. Eligible eyes were randomly assigned to either PDT/IVB or PDT/IVB/IVT. The main outcome measure was change in best-corrected visual acuity (BCVA).

RESULTS

Mean patient age was 71 ± 9 years. BCVA changes from baseline were statistically significant in both study arms at all follow-up intervals, however no significant difference was observed between the two groups regarding BCVA changes at week 12 (95% CI:-0.11-0.12 LogMAR) and other time points (all P > 0.6). Mixed model analysis revealed a significant effect from age (P < 0.001), pigment epithelial detachment (P = 0.009) and baseline BCVA (P < 0.001) on visual improvement. Significant central macular thickness (CMT) reduction occurred at all-time points as compared to baseline in both groups which was comparable between the study arms. There was no significant difference between the study arms in terms of retreatment rate (P = 0.1) and survival to the first repeat IVB injection (P = 0.065).

CONCLUSION

Additional low-dose IVT to a PDT/IVB regimen for neovascular AMD provided no beneficial effects in terms BCVA or CMT, yet demonstrated a trend toward extending the injection-free period.

Visual prostheses: the enabling technology to give sight to the blind

Millions of patients are either slowly losing their vision or are already blind due to retinal degenerative diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD) or because of accidents or injuries. Employment of artificial means to treat extreme vision impairment has come closer to reality during the past few decades. Currently, many research groups work towards effective solutions to restore a rudimentary sense of vision to the blind. Aside from the efforts being put on replacing damaged parts of the retina by engineered living tissues or microfabricated photoreceptor arrays, implantable electronic microsystems, referred to as visual prostheses, are also sought as promising solutions to restore vision. From a functional point of view, visual prostheses receive image information from the outside world and deliver them to the natural visual system, enabling the subject to receive a meaningful perception of the image. This paper provides an overview of technical design aspects and clinical test results of visual prostheses, highlights past and recent progress in realizing chronic high-resolution visual implants as well as some technical challenges confronted when trying to enhance the functional quality of such devices.

Design and development of intraocular polymeric implant systems for long-term controlled-release of clindamycin phosphate for toxoplasmic retinochoroiditis

BACKGROUND

The release of the anti-toxoplasmosis drug, clindamycin phosphate, from intraocular implants of the biodegradable polymers poly (D, L-lactic acid) (PLA) and poly (D, L-lactide-co-glycolide) (PLGA) has been studied in vitro.

MATERIALS AND METHODS

The preparation of the implants was performed by a melt-extrusion method. The developed extrudates were characterized and compared in in-vitro release profiles for elucidating the drug release mechanism. The formulations containing up to 40% w/w of drug were prepared. Release data in phosphate buffer (pH 7.4) were analyzed by high performance liquid chromatography. The release kinetics were fitted to the zero-order, Higuchi's square-root, first order and the Korsmeyer-Peppas empirical equations for the estimation of various parameters of the drug release curves. Degradation of implants was also investigated morphologically with time (Scanning Electron Microscopy).

RESULTS

It was observed that, the release profiles for the formulations exhibit a typical biphasic profile for bulk-eroding systems, characterized by a first phase of burst release (in first 24 hrs), followed by a phase of slower release. The duration of the secondary phase was found to be proportional to the molecular weight and monomer ratio of copolymers and also polymer-to-drug ratios. It was confirmed that Higuchi and first-order kinetics were the predominant release mechanisms than zero order kinetic. The Korsmeyer-Peppas exponent (n) ranged between 0.10 and 0.96. This value, confirmed fickian as the dominant mechanism for PLA formulations (n ≤ 0.45) and the anomalous mechanism, for PLGAs (0.45 < n < 0.90).

CONCLUSION

The implant of PLA (I.V. 0.2) containing 20% w/w of clindamycin, was identified as the optimum formulation in providing continuous efficient in-vitro release of clindamycin for about 5 weeks.

Development, characterizations and biocompatibility evaluations of intravitreal lipid implants

Background:

The treatment of posterior eye diseases is always challenging mainly due to inaccessibility of the region. Many drugs are currently delivered by repeated intraocular injections.

Objectives:

The purpose of this study was to investigate the potential applications of natural triglycerides as alternative carriers to synthetic polymers in terms of drug release profile and also biocompatibility for intraocular use.

Materials and Methods:

In vitro/in vivo evaluations of intravitreal implants fabricated from the physiological lipid, glyceride tripalmitate containing clindamycin phosphate as a model drug was performed. The micro-implants with average diameter of 0.4 mm were fabricated via a hot melt extrusion method. The extrudates were analyzed using scanning electron microscopy, differential scanning calorimetry, and in vitro drug dissolution studies. For biocompatibility, the implants were implanted into rabbit eyes. Clinical investigations including fundus observations, electroretinography as well as histological evaluations were performed.

Results:

In vitro tests guaranteed usefulness of the production method for preparing the homogenous mixture of the drug and lipid without affecting thermal and crystalinity characteristics of the components. In vitro releases indicated a bi-phasic pattern for lower lipid ratios, which were completed by the end of day three. With higher lipid ratios, more controlled release profiles were achieved until about ten days for a lipid ratio of 95%. Clinical observations did not show any abnormalities up to two months after implantation into the rabbit eye.

Conclusions:

These results suggest that although the implant could not adequately retard release of the present drug model yet, due to good physical characteristics and in vivo biocompatibility, it can represent a suitable device for loading wide ranges of therapeutics in treatment of many kinds of retinochoroidal disorders.

Optical coherence tomographic findings in highly myopic eyes

Optical coherence tomography (OCT) has enhanced our understanding of changes in different ocular layers when axial myopia progresses and the globe is stretched. These findings consist of dehiscence of retinal layers known as retinoschisis, paravascular inner retinal cleavage, cysts and lamellar holes, peripapillary intrachoroidal cavitation, tractional internal limiting membrane detachment, macular holes (lamellar and full thickness), posterior retinal detachment, and choroidal neovascular membranes. In this review, recent observations regarding retinal changes in highly myopic eyes explored by OCT are described to highlight structural findings that cannot be diagnosed by simple ophthalmoscopy.

Surgical management in advanced stages of retinopathy of prematurity; our experience

Retinopathy of prematurity is a potentially blinding condition. In this article we describe the surgical management for advanced stages of the disease (stages 4 and 5) Indications, options and alternative techniques are described through a review of articles and our personal experience.

Incidence and risk factors of retinopathy of prematurity in a tertiary eye hospital in Tehran

AIM

To determine the incidence and risk factors of retinopathy of prematurity (ROP) in premature infants referred to a tertiary eye hospital during 2003-7 to provide preliminary evidence about ROP in Iran.

METHODS

In a cross-sectional study, data for premature infants screened for ROP in Farabi Eye Hospital including possible risk factors and eye exams' results were recorded and analysed using chi(2), univariate and multiple regressions. Severe ROP was defined as ROP needing treatment or stage 4 or 5 of ROP.

RESULTS

Among 953 premature infants, there were 329 (34.5%) different stages of ROP. Severe ROP was seen in 22.6% (215/953) of infants (16.5%: treatable, 6.1%: advanced untreatable). The mean gestational age (GA) and birth weight (BW) of infants with severe ROP were 28.8 (SD 2.4) weeks and 1256 (389) g respectively. Univariate analysis showed a significant relation between GA, BW, oxygen therapy, blood transfusion and ROP (p<0.001), while multiple-regression methods showed GA, BW and oxygen therapy as independent predictors of ROP (p<0.001, 0.019 and 0.033, respectively).

CONCLUSION

The authors observed a relatively high incidence of ROP in this series, especially its severe form affecting relatively more mature infants, which merits further investigation. GA, BW and oxygen therapy were independent ROP determinants.

Intravitreal Bevacizumab versus Combined Bevacizumab and Triamcinolone Acetonide for Neovascular Age-Related Macular Degeneration

PURPOSE

To compare the short-term outcomes of intravitreal bevacizumab (IVB) with the combination of IVB and intravitreal triamcinolone acetonide (IVB/IVT) for treatment of neovascular age-related macular degeneration (AMD).

METHODS

This randomized clinical trial was performed on 92 eyes of 90 patients with subfoveal and juxtafoveal choroidal neovascularization (CNV) secondary to AMD. The eyes were randomly assigned to receive IVB 1.25 mg alone (53 eyes) or in combination with IVT 2 mg (39 eyes). Best-corrected visual acuity (BCVA) and fundus autofluorescence were assessed, and fluorescein angiography (FA) and optical coherence tomography (OCT) were performed at baseline and repeated 6 weeks after treatment.

RESULTS

Mean age was 70.6±8.7 (range 50-89) years and 57.7% of the patients were male. BCVA improved from 1.03±0.40 to 0.93±0.38 logMAR (P=0.001) in the IVB group and from 1.08±0.33 to 0.91±0.38 logMAR (P=0.008) in the IVB/IVT group. There was a trend toward greater visual improvement with combined therapy (P=0.06). BCVA improvement was greater in eyes with +1 versus those with +2 (P=0.049) and +3 (P<0.001) fundus autofluorescence at baseline. Mean decrease in central macular thickness was 113±115 μm (P<0.001) in the IVB group versus 53.96±125 μm (P=0.008) in the IVB/IVT group with no intergroup difference (P=0.38). FA showed decreased leakage in 57.4%, increased leakage in 12.8% and no change in 29.8% of patients in the IVB group. Corresponding figures were 60.0%, 5.7% and 34.3% in the IVB/IVT group (P=0.556).

CONCLUSION

Addition of triamcinolone acetonide to bevacizumab for treatment of neovascular AMD does not seem to significantly increase its short-term efficacy. More severe fundus autofluorescence appears to be predictive of poorer response to treatment.

Retinopathy of Prematurity: Single versus Multiple-Birth Pregnancies

PURPOSE

To compare the frequency and severity of retinopathy of prematurity (ROP) among singleton and multiple-birth neonates referred to Farabi Eye Hospital, Tehran- Iran.

METHODS

In this retrospective study, records of 99 consecutive neonates from multiplegestation pregnancies including 68 twins, 26 triplets and 5 quadruplets who were screened for ROP from 2002 to 2004 were reviewed. The frequency, severity and risk factors for ROP were determined and compared to a group of singletons who were matched in terms of gender, birth weight (BW), gestational age (GA), oxygen therapy, respiratory distress syndrome, blood transfusion, sepsis and phototherapy.

RESULTS

ROP was present in 12.1% of multiple-birth neonates as compared to 15.1% of singletons (P=0.53). Threshold ROP was present in 6.1% of multiple-birth neonates versus 7.1% of singletons (P=0.62). ROP was detected in 60% of quadruplets versus 9.6% of twins and triplets; threshold disease was observed in 40% of quadruplets as compared to 4.2% of twins and triplets (P<0.03). However, considering the effect of BW and GA, logistic regression analysis revealed no statistically significant difference in the frequency and severity of ROP among subgroups of multiple-gestation pregnancies.

CONCLUSION

There was no significant difference between multiple-birth neonates and matched singletons in terms of frequency and severity of ROP. Any apparent higher rate may be due to independent risk factors such as low birth weight and gestational age rather than multiple pregnancies per se. Screening for ROP in multiple gestation births may be conducted according to standard protocols applied for singletons.

LONG-TERM SURGICAL OUTCOME OF POSTERIOR CHOROIDAL MELANOMA TREATED BY ENDORESECTION

PURPOSE

To report the visual acuity, enucleation rates, and initial mortality after transvitreal endoresection of posterior uveal melanoma.

METHODS

Twenty consecutive patients with medium-sized posterior choroidal melanomas were treated. Vitrectomy was performed, followed by posterior hyaloid dissection, retinotomy, melanoma removal with a vitrectomy probe, retinal reattachment with perfluorocarbon liquid, and silicone oil or gas exchange.

RESULTS

Twenty patients (13 men [65%] and 7 women [35%]) were included in the study. The mean patient age +/- SD was 47.1 +/- 16 years (range, 22-70 years). Tumor thickness and tumor diameter ranged from 5.5 mm to 11 mm and 8.0 mm to 15.7 mm, respectively. Preoperative visual acuity ranged from hand motion to 20/40, and postoperative visual acuity ranged from no light perception to 20/30. Two eyes (10%) were enucleated during tumor resection due to severe bleeding. Enucleation was performed on 3 eyes (15%) during follow-up due to tumor recurrence at the edge of surgical coloboma in 1 patient, new focus of tumor in another sector distant from surgical coloboma in 1 patient, and painful blind eye in 1 patient. Fifteen eyes (75%) were saved. One patient (5%) died of metastasis to the liver. The mean follow-up period +/- SD was 89.55 +/- 38.4 months (range, 24-132 months.

CONCLUSION

These data suggest that transvitreal endoresection of posterior uveal melanoma is an acceptable management option to conserve the globe and functional vision in selected patients. Distant metastasis is an infrequent event in this modality of treatment.

Pars plana Ahmed valve implant and vitrectomy in the management of neovascular glaucoma

BACKGROUND AND OBJECTIVE

To evaluate the efficacy and safety of the pars plana Ahmed glaucoma valve (New World Medical, Inc., Rancho Cucamonga, CA) implant combined with pars plana vitrectomy and panretinal photocoagulation for the management of neovascular glaucoma in patients with vitreous hemorrhage.

PATIENTS AND METHODS

The records of 18 eyes of 17 consecutive patients with neovascular glaucoma who had undergone pars plana vitrectomy and pars plana Ahmed valve implant were evaluated. The patients were observed for a mean time of 14.2 months (range, 6 to 28 months).

RESULTS

Mean preoperative intraocular pressure with oral and two or three topical antiglaucoma medications was 53.3 +/- 10 mm Hg, and mean postoperative intraocular pressure without oral antiglaucoma medications was 16.3 +/- 7.1 mm Hg (P < .0001) at the final visit. Overall success rate was 72.2%, defined as an intraocular pressure of 5 to 21 mm Hg with or without antiglaucoma medication. A postoperative hypertensive phase occurred in 7 patients (38.8%), of which all but one responded to medical therapy. Visual acuity was stabilized or improved in 77.7% of the eyes. There was one case of each of the following adverse events: mild vitreous cavity hemorrhage, hypotony, choroidal effusion, epiretinal membrane, corneal edema, and corneal ulcer. Two cases developed phthisis bulbi and lost light perception.

CONCLUSIONS

Pars plana vitrectomy and Ahmed valve implantation seems to be a viable surgical modality in the management of neovascular glaucoma and coexisting posterior segment pathology with a relatively low rate of serious permanent postoperative complications.

Single-session photodynamic therapy combined with intravitreal bevacizumab and triamcinolone for neovascular age-related macular degeneration

Background

To evaluate the efficacy of triple therapy consisting of single-session photodynamic therapy (PDT), intravitreal bevacizumab (IVB) and intravitreal triamcinolone (IVT) as initial pulse therapy followed by repeat intravitreal bevacizumab injections for maintenance treatment in neovascular age-related macular degeneration (AMD).

Methods

In a prospective interventional case series, patients with subfoveal choroidal neovascularization (CNV) secondary to AMD underwent pulse therapy with single-session PDT according to the standard protocol followed by 1.25 mg IVB and 2 mg IVT 48 hours later. Best corrected visual acuity (BCVA) was assessed and optical coherence tomography (OCT) and fluorescein angiography (FA) were performed prior to treatment. BCVA and OCT measurements were repeated at 6 week intervals and FA was obtained after 12 weeks and when necessary thereafter. Repeat injections of IVB were performed based on fluorescein angiographic evidence of CNV leakage.

Results

This series included 17 eyes of 17 patients with mean age of 67.6 ± 7.2 years. Mean follow up duration was 50.4 ± 15.5 weeks. Mean BCVA prior to treatment was 0.74 ± 0.33 logMAR which improved to 0.52 ± 0.36 logMAR after 12 weeks (P = 0.012) and 0.41 ± 0.38 logMAR after 24 weeks (P = 0.001). Mean pretreatment central macular thickness (CMT) was 395 ± 181μ which was significantly reduced to 217 ± 69μ (P = 0.005), 231 ± 79μ (P = 0.028) and 221 ± 87μ (P = 0.05) six, twelve and twenty-four weeks after initial treatment respectively. Visual acuity improvement and CMT reduction was maintained during the follow-up period. IVB injections were repeated once, twice and three times in 10, 7 and 2 eyes at a mean interval of 20.2 ± 10.1, 19 ± 13.7 and 15 ± 1.4 weeks after initial therapy, respectively.

Conclusion

Initial pulse triple therapy consisting of single-session PDT combined with IVB and IVT improves vision and reduces CMT in neovascular AMD. Repeat IVB injections maintain the visual gain from the initial combination therapy.

Prevention of Corneal Neovascularization

PURPOSE

To evaluate the effect of topically administered agents doxycycline, triamcinolone, low molecular weight heparin (LMWH), and flurbiprofen on experimental corneal neovascularization in rats.

METHODS

Chemical cauterization of cornea was performed in 36 eyes of 36 rats by using silver nitrate/potassium nitrate sticks. Topical instillation of doxycycline, triamcinolone, LMWH, flurbiprofen, and normal saline solution was continued for 7 days. Percent areas of cornea covered by neovascularization and covered by scar in each group were calculated by use of computer software on digital photographs. Groups were compared for any significant (P < 0.05) differences among them.

RESULTS

The means of percent area of corneal neovascularization in triamcinolone, doxycycline, flurbiprofen, LMWH, and control groups were 13.3%, 35.5%, 50.6%, 66.7%, and 74.9%, respectively. The triamcinolone and doxycycline groups were different from control group (P < 0.05). There was no significant difference in the percent area of neovascularization between the LMWH and flurbiprofen groups compared with the controls. Although the effects of LMWH and flurbiprofen were not significant, there seemed to be a trend, and the lack of significance may be related to small sample size. Because the mechanisms of action of these agents are not identical to each other, performing other studies using combinations of them seems to be reasonable. There were no significant differences in percent area of corneal scar among groups.

CONCLUSION

Topical instillation of commercially available triamcinolone and doxycycline seems to diminish corneal neovascularization caused by chemical cauterization of cornea in rats.

The Effect of Combinations of Flurbiprofen, Low Molecular Weight Heparin, and Doxycycline on the Inhibition of Corneal Neovascularization

PURPOSE

To determine the efficacy of various combinations of flurbiprofen, low molecular weight heparin (LMWH), and doxycycline on the inhibition of corneal neovascularization in rats.

METHODS

Chemical cauterization of the cornea in 32 eyes of 32 rats was performed using silver nitrate/potassium nitrate sticks. The animals were divided into 4 groups. Topical instillation of 0.015% flurbiprofen with 5 mg/mL LMWH (group 1); flurbiprofen with 10 mg/mL doxycycline (group 2); doxycycline with LMWH (group 3), and saline (group 4; control) was performed twice a day for 7 days. Slit-lamp photography was used to determine the percent areas of cornea covered by neovascularization and also by scar in each group. The means were compared to find any significant (P < 0.05) difference between groups. The animals were euthanized and the eyes enucleated for histological evaluation.

RESULTS

The mean of percent area of corneal neovascularization 5 in group 1 was 48.5 +/- 13.1; group 2, 6.6 +/- 5.5; group 3, 22.0 +/- 27.6 and group 4, 64.6 +/- 9. The means of percent area of neovascularization in groups 2 and 3 were significantly lower compared with control and group 1. There was no significant difference in the percent corneal neovascularization between groups 2 and 3 or between group 1 and the control group. Histological findings were consistent with slit-lamp evaluations.

CONCLUSIONS

Topical instillation of combinations of doxycycline with either flurbiprofen or LMWH can effectively inhibit corneal neovascularization made by chemical cauterization of the cornea in rats.

Intravitreal Toxicity of Levofloxacin and Gatifloxacin

BACKGROUND AND OBJECTIVE

To assess the retinal toxicity of varying concentrations of intravitreally injected gatifloxacin and levofloxacin.

MATERIALS AND METHODS

In this experimental, controlled study, levofloxacin (initial concentration = 25 mg/mL) and gatifloxacin (initial concentration = 2 mg/mL) were titrated using 5% dextrose solution to concentrations of 2,500 to 156 microg/0.1 mL and 400 to 50 microg/0.1 mL, respectively. Each concentration was injected intravitreally into two rabbit eyes (one eye per animal); two control eyes were injected with 0.1 mL of 5% dextrose solution. All animals were examined and electroretinography was performed before and 14 days after injection. The animals were killed at 14 days; the eyes were enucleated and prepared for light microscopy.

RESULTS

The levofloxacin group exhibited significant decreases in electroretinography in the eyes injected with 1,250 and 2,500 microg. No signs of retinal toxicity were observed on slit-lamp examination, indirect ophthalmoscopy, or light microscopy in all eyes injected intravitreally with 625 microg or less of levofloxacin or in any eyes given gatifloxacin.

CONCLUSION

Intravitreally injected concentrations of 625 microg or less of levofloxacin and 400 microg or less of gatifloxacin appeared nontoxic.