SF 6 COMPARED WITH C 2 F 6 FOR INFERIOR RHEGMATOGENOUS RETINAL REPAIR : The Manchester Pseudophakic Retinal Detachment Study

PURPOSE

To compare SF 6 relative with C 2 F 6 in the anatomical and functional outcomes following pars plana vitrectomy for uncomplicated primary pseudophakic rhegmatogenous retinal detachment with inferior causative breaks.

METHODS

This is a retrospective, comparative study on eyes with pseudophakic rhegmatogenous retinal detachment with inferior causative breaks that had small-gauge pars plana vitrectomy repair using SF 6 and C 2 F 6 tamponade between 2011 and 2020 at a tertiary centre in the United Kingdom. Primary outcome was single surgery anatomical success, and the secondary outcome was best-corrected visual acuity. Propensity score matching, using preoperative findings as covariates to account for relevant confounders, was performed.

RESULTS

From 162 pseudophakic rhegmatogenous retinal detachment eyes with inferior causative breaks, the median (interquartile range) follow-up was 82 (52-182) days. The single surgery anatomical success was 156 (96.3%) overall: 47 of 47 (100.0%) and 109 of 115 (94.8%) in the SF 6 and C 2 F 6 groups, respectively ( P = 0.182). Relative to the SF 6 group, the C 2 F 6 group had a higher mean number of tears (SF 6 : 3.1[2.0], C 2 F 6 : 4.5[2.7], P = 0.002) and greater retinal detachment extent (SF 6 : 5.3[2.9], C 2 F 6 : 6.2[2.6] clock hours, P = 0.025). Following propensity score matching analysis, 80 eyes were matched with 40 in each group to homogenize preoperative factors. No significant difference was found in single surgery anatomical success and best-corrected visual acuity between the groups following propensity score matching.

CONCLUSION

Primary pars plana vitrectomy with gas tamponade leads to a high single surgery anatomical success rate in uncomplicated pseudophakic rhegmatogenous retinal detachment with inferior causative breaks with no additional benefit associated with long-acting tamponade when comparing C 2 F 6 with SF 6 .

In vivo evaluation of a Nano-enabled therapeutic vitreous substitute for the precise delivery of triamcinolone to the posterior segment of the eye

This study focused on the design of a thermoresponsive, nano-enabled vitreous substitute for the treatment of retinal diseases. Synthesis of a hydrogel composed of hyaluronic acid and a poloxamer blend was undertaken. Poly(D,L-lactide-co-glycolide) acid nanoparticles encapsulating triamcinolone acetonide (TA) were synthesised with a spherical morphology and mean diameter of ~ 153 nm. Hydrogel fabrication and nanoparticle loading within the hydrogel was confirmed via physicochemical analysis. Gelation studies indicated that hydrogels formed in nine minutes and 10 min for the unloaded and nanoparticle-loaded hydrogels, respectively. The hydrogels displayed in situ gel formation properties, and rheometric viscoelastic studies indicated the unloaded and loaded hydrogels to have modulus values similar to those of the natural vitreous at 37 °C. Administration of the hydrogels was possible via 26G needles allowing for clinical application and drug release of triamcinolone acetonide from the nanoparticle-loaded hydrogel, which provided sustained in vitro drug release over nine weeks. The hydrogels displayed minimal swelling, reaching equilibrium swelling within 12 h for the unloaded hydrogel, and eight hours for the nanoparticle-loaded hydrogel. Biodegradation in simulated vitreous humour with lysozyme showed < 20% degradation within nine weeks. Biocompatibility of both unloaded and loaded hydrogels was shown with mouse fibroblast and human retinal pigment epithelium cell lines. Lastly, a pilot in vivo study in a New Zealand White rabbit model displayed minimal toxicity with precise, localised drug release behaviour, and ocular TA levels maintained within the therapeutic window for the 28-day investigation period, which supports the potential applicability of the unloaded and nanoparticle-loaded hydrogels as vitreous substitutes that function as drug delivery systems following vitrectomy surgery.

Impact of COVID-19 on ophthalmic surgical procedures in sub-Saharan Africa: a multicentre study

BACKGROUND

The COVID-19 pandemic had a profound impact on healthcare and ophthalmology services globally. Numerous studies amongst various medical and surgical specialties showed a reduction in patient attendance and surgical procedures performed. Prior published ophthalmic literature focused on specific types of procedures and were usually single centre. The current study attempts to quantify the impact on a larger scale, namely that of sub-Saharan Africa, and to include all ophthalmic subspecialties.

METHODS

This is a retrospective analysis of the surgical records from 17 ophthalmology centres in seven countries located in East, Central, West and Southern Africa. The date of declaration of the first lockdown was used as the beginning of the pandemic and the pivot point to compare theatre records one year prior to the pandemic and the first year of the pandemic. We examined the total number of surgical procedures over the two year period and categorized them according to ophthalmic subspecialty and type of procedure performed. We then compared the pre-pandemic and pandemic surgical numbers over the two year period.

RESULTS

There were 26,357 ophthalmic surgical procedures performed with a significant decrease in the first year of the pandemic (n = 8942) compared to the year prior to the pandemic (n = 17,415). The number of surgical procedures performed was lower in the first year of the pandemic compared to the year prior to the pandemic by 49% [Incidence rate ratio (IRR) 0.51, 95% CI 0.41-0.64), 27% (0.73, 0.55-0.99), 46% (0.54, 0.30-0.99), 40% (0.60, 0.39-0.92) and 59% (0.41, 0.29-0.57) in sub-Saharan Africa (4 regions combined), West, Central, East and Southern Africa, respectively]. The number of surgical procedures in the different sub-specialty categories in sub-Saharan Africa (4 regions combined) was significantly lower in the first year of the pandemic compared to the year prior to the pandemic, except for glaucoma (IRR 0.72, 95% CI 0.52-1.01), oncology (0.71, 0.48-1.05), trauma (0.90, 0.63-1.28) and vitreoretinal (0.67, 0.42-1.08) categories.

CONCLUSION

This study provides insight into the impact of the COVID-19 pandemic in multiple regions and countries on the African continent. The identification of which surgical subspecialty was most affected by the COVID-19 pandemic in each region allows for better planning and resource allocation to address these backlogs.

THE LONG-TERM RECOVERY OF VISION IN PSEUDOPHAKIC MACULA-OFF RHEGMATOGENOUS RETINAL DETACHMENTS

PURPOSE

To assess the long-term visual recovery in uncomplicated macula-off pseudophakic rhegmatogenous retinal detachment treated with pars plana vitrectomy and gas tamponade in the absence of other visual comorbidities.

METHODS

Single-center retrospective longitudinal study on eyes with macula-off pseudophakic rhegmatogenous retinal detachment successfully treated with pars plana vitrectomy between 2011 and 2020 and with at least 2 follow-ups (FU), first gas-free FU (first-FU) and a final-FU, were included. Patients with subsequent ocular surgery or comorbidities affecting best-corrected visual acuity were excluded. The duration between operation date and final-FU was calculated (total days FU) and split into total days quintiles-1: ≤57, 2: >57 and ≤77, 3: >77 and ≤152, 4: >152 and ≤508, and 5: >508 days. Multivariable regression was performed with logMAR gain between the first and the final-FU as the dependent variable.

RESULTS

In 209 eyes, the authors report association with increase of logMAR gain between the first and the final-FU, with reducing clock hours of pseudophakic rhegmatogenous retinal detachment ( P = 0.041) and relative to the total days Quintile 1. Mean (SD) logMAR gain between the first and the final-FU was 0.02 (0.07) in the first quintile, increasing to 0.14 (0.13) ( P < 0.001) by the fifth quintile on multivariable regression. For patients not achieving 0.30 logMAR at the first-FU, this was attained at the final-FU with a sensitivity of 51.9% and specificity of 95.5% at a cut off ≤0.58 logMAR at the first-FU (area under the curve 0.756 [95% confidence interval 0.664-0.848], P < 0.001).

CONCLUSION

The authors report a significant time-dependent visual improvement after uncomplicated pars plana vitrectomy with gas tamponade for macula-off pseudophakic rhegmatogenous retinal detachment without visual confounders and provide important quantitative data for counselling patients with macula-off repair.

Ocular manifestations of HIV infection at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa

BACKGROUND

The pattern of HIV-associated eye disease has changed with ongoing advancements in highly active antiretroviral therapy (HAART). HIV-infected individuals now live longer, enabling us to observe the long-term effects of HIV and HAART on the eye. There are few recent studies on HIV-related ocular disease in sub-Saharan Africa.

OBJECTIVES

To describe the ocular manifestations of HIV in patients attending the Nthabiseng HIV clinic at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa.

METHODS

A cross-sectional study was conducted in 2021 and 2022 using convenience sampling of patients at the HIV clinic. The participants' clinical history was taken, their files were reviewed, and they underwent ocular examination. Correlation between eyes was managed by taking disease in one eye as the presence of disease in the participant. Descriptive statistics were used to summarise participant characteristics. Univariate and multivariate logistic regression models were used to assess the odds ratio (OR) of developing HIV-associated ocular diseases, and a p-value of <0.05 was used to define statistical significance.

RESULTS

There were 182 participants (139 females and 43 males), with a mean (standard deviation) age of 48.9 (10.6) years. The most common anterior segment diagnoses were conjunctival microangiopathy (34.6%), pinguecula (31.3%) and cataracts (30.2%), while the most common posterior segment finding was peripheral retinal scarring with features in keeping of previous cytomegalovirus retinitis (24.2%). Notably, only 1.1% of patients had HIV retinopathy. A CD4 count <200 cells/μL showed an increased OR for cataracts (OR 4.24; p=0.003) and any anterior segment diagnoses (OR 10.05; p=0.029), while a CD4 count ≥200 cells/μL showed an increased risk of conjunctival microangiopathy (OR 2.14; p=0.017).

CONCLUSION

With the advent of HAART, ocular manifestations of HIV are changing and the incidence of severe ocular opportunistic infections and HIV retinopathy has decreased precipitously. Although this study has shown that patients with a CD4 count <200 cells/μL are at increased risk of developing anterior ocular manifestations of HIV, including cataracts, these diseases are relatively innocuous or easily treatable. Routine ocular screening of HIV patients seems to be substantially less important now than it was in the pre-HAART era.

The Role of Subretinal Injection in Ophthalmic Surgery: Therapeutic Agent Delivery and Other Indications

Subretinal injection is performed in vitreoretinal surgery with two main aims, namely, the subretinal delivery of therapeutic agents and subretinal injection of fluid to induce a controlled and localized macular detachment. The growing interest in this technique is mainly related to its suitability to deliver gene therapy in direct contact with target tissues. However, subretinal injection has been also used for the surgical management of submacular hemorrhage through the subretinal delivery of tissue plasminogen activator, and for the repair of full-thickness macular holes, in particular refractory ones. In the light of the increasing importance of this maneuver in vitreoretinal surgery as well as of the lack of a standardized surgical approach, we conducted a comprehensive overview on the current indications for subretinal injection, surgical technique with the available variations, and the potential complications.

Long-Term Safety and Efficacy of Pars Plana Vitrectomy for Uveitis: Experience of a Tertiary Referral Centre in the United Kingdom

AIM

To evaluate the effectiveness of pars plana vitrectomy (PPV) without macular intervention on uveitis eyes with persistent vitreous inflammation/opacities in terms of visual acuity (VA), intraocular inflammation and macular profile.

METHODS

We carried out a single-center retrospective study of patients with uveitic eyes that underwent PPV without intervention on the macula due to persistent vitreous inflammation/opacities. The primary outcome measures were best-corrected visual acuity (BCVA), intraocular inflammation and macular profile at 3, 12 and 24 months after surgery.

RESULTS

Twenty-seven eyes of twenty-six patients were analyzed. Overall, 77.8% had an improvement of VA (55% by 0.3 LogMAR or more); 62.5% of patients had no intraocular inflammation, and the number of patients on systemic steroids and second-line immunosuppressives was reduced by 26% at 12 months; 87.5% of patients had resolution of macular oedema at 12 months.

CONCLUSION

PPV for persistent vitreous inflammation/opacities is safe and effective, showing beneficial outcomes in terms of improvement of BCVA and the reduction in inflammation.

Advances in Polysaccharide- and Synthetic Polymer-Based Vitreous Substitutes

The vitreous humour is a gel-like structure that composes the majority of each eye. It functions to provide passage of light, be a viscoelastic dampener, and hold the retina in place. Vitreous liquefaction causes retinal detachment and retinal tears requiring pars plana vitrectomy for vitreous substitution. An ideal vitreous substitute should display similar mechanical, chemical, and rheological properties to the natural vitreous. Currently used vitreous substitutes such as silicone oil, perfluorocarbon liquids, and gases cannot be used long-term due to adverse effects such as poor retention time, cytotoxicity, and cataract formation. Long-term, experimental vitreous substitutes composed of natural, modified and synthetic polymers are currently being studied. This review discusses current long- and short-term vitreous substitutes and the disadvantages of these that have highlighted the need for an ideal vitreous substitute. The review subsequently focuses specifically on currently used polysaccharide- and synthetic polymer-based vitreous substitutes, which may be modified or functionalised, or employed as the derivative, and discusses experimental vitreous substitutes in these classes. The advantages and challenges associated with the use of polymeric substitutes are discussed. Innovative approaches to vitreous substitution, namely a novel foldable capsular vitreous body, are presented, as well as future perspectives related to the advancement of this field.

Optic neuritis: A South African hospital-based prospective study protocol

Background

Optic neuritis is a relatively common disease with an estimated lifetime risk of 0.6 per 1000; the estimated prevalence is 1–5 per 100 000/year. It occurs because of inflammation of the optic nerve from a variety of causes. The diagnosis of the disorder is established clinically and current literature is predominantly based on white patients from high-income countries. Optic neuritis presents differently in black patients compared to white patients. This study aims to assess the presentation and outcome of optic neuritis patients in a South African setting.

Methods

This is a prospective, hospital-based cohort study that will enrol patients with optic neuritis presenting to either the neurology department at Chris Hani Baragwanath Academic Hospital or the ophthalmology department at St John Eye Hospital, both in Johannesburg, South Africa. The specific aetiologies, clinical presentation and radiological findings will be studied, and the patient’s course over one year will be documented in three-monthly follow-up visits. A specific group of patients with Neuromyelitis Optica Spectrum Disorders (NMOSD) and Myelin Oligodendrocyte Glycoprotein Associated Disorders (MOGAD) optic neuritis will be followed up for 5 years at yearly intervals.

Discussion

This study represents one of the few cohort studies in Sub-Saharan Africa that seeks to investigate optic neuritis. Our hope is that it will lead to better insights regarding the presentation, course and outcome of this condition. We will also analyse the data with a view of developing a predictive model for good visual outcome.

Prevalence of complications in eyes with nanophthalmos or microphthalmos: protocol for a systematic review and meta-analysis

INTRODUCTION

Microphthalmos and nanophthalmos are uncommon ocular conditions, whereby affected eyes have smaller dimensions compared to the normal population. Microphthalmos and nanophthalmos present several challenges to ophthalmologists; they have spontaneous and post-operative sequelae such as high hyperopia, angle-closure glaucoma, uveal effusion syndrome, and retinal detachment. This systematic review and meta-analysis intends to assess the prevalence of both the spontaneous complications associated with nanophthalmos and microphthalmos, as well as the post-surgical complications associated with nanophthalmos or microphthalmos.

METHODS AND ANALYSIS

Articles will be searched for, on four online databases: PubMed, EMBASE, Scopus, and Web of Science. Two independent reviewers will identify the studies according to prespecified inclusion and exclusion criteria. All studies included with participants diagnosed with microphthalmos or nanophthalmos in one or both eyes, will be included if they have (i) more than 4 cases and (ii) defined microphthalmos/nanophthalmos as an axial length of < 21 mm or a high lens/eye volume ratio. Nanophthalmos may have an additional diagnostic criterion of posterior wall thickness greater than 1.7 mm. The prevalence of the following complications will be assessed: high hyperopia (spherical equivalent >3D), angle closure glaucoma, uveal effusion syndrome, retinal detachment, and chorioretinal folds. Studies that will be excluded are those that have not adequately defined the criteria for the diagnosis of nanophthalmos or microphthalmos, those studies that have less than five cases, studies with criteria not defined above, and deemed unsuitable, and studies in languages other than English with no published translation. Relevant data will be extracted and assessed for the risk of bias in each article using a modified Joanna Briggs Institute (JBI) assessment tool. The data will then be pooled to determine the prevalence of complications among patients with microphthalmos and nanophthalmos. If the data allows, subgroup analysis will be carried out according to axial length as well as subtype of microphthalmos/nanophthalmos (simple, complex, relative anterior, and posterior).

DISCUSSION

Although nanophthalmos is an uncommon condition that affects the eye, its management and complications can be sight-threatening. Thus, it is important to counsel patients and their families correctly (in the case of children) upon diagnosis and prior to any surgical intervention. This can only be done if the overall prevalence of complications is known.

REGISTRATION

PROSPERO CRD42021227847.

Treatment Outcome of Tubercular Uveitis in a High TB and HIV Setting: A Prospective Cohort Study

Purpose

To determine the time to resolution of inflammation in tubercular uveitis (TBU) cases on standard anti-tubercular treatment. Sub-analysis of time to resolution according to HIV status was also performed.

Patients and Methods

A prospective cohort study of presumed idiopathic uveitis cases >18 years underwent the tuberculin skin test, QuantiFERON-TB Gold test, and ocular tuberculosis (TB) polymerase chain reaction test. Adult TBU cases were treated with standard anti-tubercular therapy (and corticosteroids) for 9 months. Cases were followed-up for resolution of inflammation at 1.5, 3, 6, 9, 12 and 15 months post-diagnosis. Outcome measure was resolution of inflammation on ≤10 mg oral prednisone per day.

Results

Seventy-nine presumed idiopathic uveitis cases were enrolled in the study, 49 (62%) were diagnosed with TBU. The mean (SD) age of TBU cases at diagnosis was 41.8 (13.4) years. Using a multilevel mixed effects model, resolution was achieved at 6 months in the TBU cases (OR = 1.21; 95% CI, 1.03-1.41; P = 0.017). Using generalized estimating equations, resolution was also achieved at 6 months in the TBU cases (OR = 1.21; 95% CI, 1.05-1.39; P = 0.008). The HIV-positive cases (OR = 1.62; 95% CI, 1.13-2.31; P = 0.008) and the HIV-negative cases (OR = 1.25; 95% CI, 1.06-1.48; P = 0.009) achieved resolution at 9 months.

Conclusion

Resolution of inflammation in TBU cases on anti-tubercular treatment with corticosteroids was achieved at 6 months and maintained throughout the study. Our study suggests a minimum of 6 months treatment is required for significant resolution. Resolution of inflammation in HIV-positive and HIV-negative TBU cases needs to be further explored.

Tubercular Uveitis in Uveitis Cases in a High TB and HIV Setting: A Prospective Cohort Study

Purpose

The diagnosis of tubercular uveitis (TBU) is difficult. The lack of a diagnostic gold standard has contributed to challenges in determining the true prevalence and clinical predictors of TBU. We aimed to determine the proportion of TBU cases in adults with uveitis and to examine clinical features associated with TBU.

Methods

A prospective cohort study of adult uveitis cases after exclusion of other specific etiologies. The diagnosis of TBU was based on a composite reference of: any clinical signs of uveitis; exclusion of other causes of uveitis; and positive QuantiFERON-Gold test, tuberculin skin test, and/or ocular TB polymerase chain reaction.

Results

Of 79 cases analyzed, 49 (62%) had TBU. Female sex (P = 0.001) and chronic uveitis (P = 0.006) cases were more common in the TBU group than the non-TBU group whereas diffuse choroiditis (P = 0.010) and HIV-positive (P = 0.001) cases were less common. Choroidal granulomas (P = 0.176) and serpiginous-like choroiditis (P = 0.292) were more common in TBU group, albeit not significantly. On univariate analysis, female sex (odds ratio, 5.1; P = 0.002), negative HIV status (odds ratio, 0.2; P = 0.001), and chronic uveitis (odds ratio, 4.1; P = 0.008) were associated with TBU. A negative HIV test was associated with TBU on multivariate analysis (P = 0.049).

Conclusions

A high proportion of cases had TBU. Our study did not significantly confirm some of the clinical features associated with TBU reported in other studies.

Translational Relevance

Our study highlights the difficulties in determining the proportion and clinical predictors of TBU, especially in the absence of a gold standard diagnostic test.

Global prevalence and clinical outcomes of tubercular uveitis: a systematic review and meta-analysis

Tubercular uveitis (TBU) is an inflammation/infection of the eye secondary to Mycobacterium tuberculosis infection. The difficulty in making the diagnosis has resulted in variable prevalence and clinical response rates. We aimed to determine the global prevalence of TBU in uveitis patients stratified by TB high-burden countries (HBCs) and non-HBCs and by geographic regions and the clinical response of TBU to antitubercular treatment We performed a systematic review and meta-analysis of TBU studies published in PubMed, Scopus and EMBASE, up to June 30, 2020. A random effects model was used for all meta-analyses. Of 5,018 articles identified, 70 prevalence studies (65,607 uveitis and 3,166 TBU cases) and 18 clinical outcome studies (1,570 TBU cases; 1,304 responded to anti-tubercular therapy [ATT]) were analyzed. The overall weighted prevalence of TBU was 4.0% (95% CI, 3-5); in TB HBCs it was 7.0% (95% CI, 5-11), non-HBCs 3.0% (95% CI, 2-4), and sub-Saharan Africa 11.0% (95% CI, 8-15). The overall weighted clinical response was 82.0% (95% CI, 75-89). Despite the difficulty in diagnosing TBU, the prevalence is expectantly higher in HBCs, and sub-Saharan Africa and the clinical outcome is poor. Standardization of diagnostic criteria and ATT is warranted in future cohort studies.

Cost comparison between botulinum neurotoxin and surgery in the treatment of infantile esotropia in a tertiary public hospital

Objective

To compare the cost implications of botulinum neurotoxin (BNT) injection to surgery in infantile esotropia (IE) in a public/government funded hospital.

Methods and analysis

A simple costing comparison was undertaken for a randomised clinical trial in IE. Patients were randomised to receive either BNT or standard surgery. The participants in the BNT arm were further subdivided into subgroups based on their age in months and degree of esotropia in prism dioptres (PD) at presentation: G1 ≤60 PD/24 months, G2 ≤24 months/>60 PD, G3 >24 months/≤60 PD, G4 >24 months/>60 PD. The costs were calculated for each arm from primary treatment to eventual satisfactory outcome defined as orthophoria or microtropia (≤10 PD). A bottom-up costing analysis was done for single and multiple procedures for each arm. Comprehensive variable costs as well as fixed costs were calculated at each point of intervention and expressed in local currency ZAR (US$1=ZAR15.00). Costing was analysed for surgery and BNT subgroups (based on clinical success).

Results

There were 101 patients enrolled in the trial. 54 in the BNT arm and 47 in the surgery arm. Cost for single surgery and single BNT was ZAR 7743.04 and 1713.14, respectively. A favourable clinical outcome was achieved in 72% of surgery arm and 37% of BNT arm. The mean cost for eventual favourable outcome in BNT arm was ZAR9158.08 and in surgery arm ZAR9124.27 (p=0.26). Mean cost in G1 was ZAR6328.45, in G2 ZAR7197.45, in G3 ZAR11891.93 and G4 ZAR12882.44 (p=0.018).

Conclusion

BNT has a cost-benefit in IE and is a viable option in the primary treatment of IE in resource constrained regions. Clinical outcomes and economic benefit in smaller angle of esotropia and younger patients are comparable to surgery.

Nodular Posterior Scleritis Masquerading as a Subretinal Mass

This is the case report of a 50-year-old female with no systemic comorbidities who presented to the eye clinic with a 1-month history of right-sided eye pain and visual loss. Examination revealed no signs of inflammation in the right eye, with no proptosis or conjunctival injection. A relative afferent pupillary defect was present with no inflammatory cells in the vitreous. On fundoscopy, there was a swollen disc, a large superior creamy white subretinal mass associated with a shallow overlying retinal detachment. B-scan ultrasonography confirmed the presence of a subretinal mass. Hematological investigations revealed an elevated erythrocyte sedimentation rate. Infective and autoimmune markers were negative. A diagnosis was made of nodular posterior scleritis and the patient was treated with intravenous corticosteroids initially, and subsequently switched to oral corticosteroids. There was complete resolution of the mass with optic atrophy as a result. Posterior nodular scleritis is an extremely rare potentially vision-threatening ocular condition that requires multimodal investigations to diagnose and treat appropriately.

Botulinum neurotoxin injections in essential infantile esotropia-a comparative study with surgery in large-angle deviations

PURPOSE

To compare botulinum neurotoxin (BNT) injections to surgery as first-line therapy in large-angle essential infantile esotropia (IE).

PATIENTS AND METHODS

Children between the ages 6 months and 6 years with IE of ≥40 prism dioptres (PD) were randomised to either a maximum of three BNT injections or surgical intervention of bimedial rectus muscle recession for angles ≤60 PD and augmented with BNT injection in angles >60 PD. Time taken for each procedure was documented. Orthophoria or misalignment of ≤10 PD was regarded as a complete response (CR). Follow-up visits were done at 3, 6, 12 and 24 weeks.

RESULTS

Mean (SD) age and baseline angle of esotropia were 26.9 (14.5) months and 61.9 PD (12.8), respectively, for the overall cohort. The proportion of children who achieved CR was significantly higher in the surgery arm compared to the BNT injection arm (OR = 4.01, 95% CI 1.74-9.22) but the time taken was six times longer (p < 0.0001). In the BNT arm, 55.2% of children aged ≤24 months and 16% of children >24 months achieved CR. In children with esotropia ≤60 PD, CR was achieved in 50% while those with esotropia >60 PD CR was achieved in 25%.

CONCLUSION

Surgery remains the gold standard for treatment of esotropia but BNT injection is a safe and effective alternative in children ≤24 m and with smaller angles of esotropia ≤60 PD in resource-limited centres.

Hydrogel Biomaterials for Application in Ocular Drug Delivery

There are many challenges involved in ocular drug delivery. These are a result of the many tissue barriers and defense mechanisms that are present with the eye; such as the cornea, conjunctiva, the blinking reflex, and nasolacrimal drainage system. This leads to many of the conventional ophthalmic preparations, such as eye drops, having low bioavailability profiles, rapid removal from the administration site, and thus ineffective delivery of drugs. Hydrogels have been investigated as a delivery system which is able to overcome some of these challenges. These have been formulated as standalone systems or with the incorporation of other technologies such as nanoparticles. Hydrogels are able to be formulated in such a way that they are able to change from a liquid to gel as a response to a stimulus; known as "smart" or stimuli-responsive biotechnology platforms. Various different stimuli-responsive hydrogel systems are discussed in this article. Hydrogel drug delivery systems are able to be formulated from both synthetic and natural polymers, known as biopolymers. This review focuses on the formulations which incorporate biopolymers. These polymers have a number of benefits such as the fact that they are biodegradable, biocompatible, and non-cytotoxic. The biocompatibility of the polymers is essential for ocular drug delivery systems because the eye is an extremely sensitive organ which is known as an immune privileged site.

Retinal nerve fibre layer thickness in a normal black South African population

BACKGROUND

The measurement of retinal nerve fibre layer (RNFL) thickness on spectral domain OCT (SD-OCT) are compared with built-in age- and gender-matched European normative databases and this difference is used to assist with glaucoma diagnosis. However, there are differences in RNFL thickness between population groups. Therefore, using the built in European normative database as a comparison across all population groups could lead to erroneous results, due to the basic assumption that the normative values for non-European populations are the same as their European counterparts.

METHODS

Cross-sectional study of RNFL thickness in normal black South African patients.

RESULTS

One hundred and thirty-two eyes of 132 patients were enroled in this study. The mean (SD) age of patients in this study was 41.3 (12.5) years. Males comprised 40.9% (n = 54; p = 0.0367). All RNFL sectors except the temporal sector were significantly thicker than the reference database. The RNFL sectors measured as follows: global (108.7 µm, p < 0.001), superotemporal (152.4 µm, p < 0.001), superonasal (132.6 µm, p < 0.001), inferotemporal (150.1 µm, p < 0.001), inferonasal (129.2 µm, p < 0.001), nasal (77.7 µm, p < 0.001), temporal 74.8 µm, p = 0.9534).

CONCLUSION

The RNFL thickness of normal black South Africans is significantly thicker than that of the European database on the Spectralis SD-OCT. This needs to be taken into account when performing RNFL thickness measurements on black patients.

Advances in Biodegradable Nano-Sized Polymer-Based Ocular Drug Delivery

The effective delivery of drugs to the eye remains a challenge. The eye has a myriad of defense systems and physiological barriers that leaves ocular drug delivery systems with low bioavailability profiles. This is mainly due to poor permeability through the epithelia and rapid clearance from the eye following administration. However, recent advances in both polymeric drug delivery and biomedical nanotechnology have allowed for improvements to be made in the treatment of ocular conditions. The employment of biodegradable polymers in ocular formulations has led to improved retention time, greater bioavailability and controlled release through mucoadhesion to the epithelia in the eye, amongst other beneficial properties. Nanotechnology has been largely investigated for uses in the medical field, ranging from diagnosis of disease to treatment. The nanoscale of these developing drug delivery systems has helped to improve the penetration of drugs through the various ocular barriers, thus improving bioavailability. This review will highlight the physiological barriers encountered in the eye, current conventional treatment methods as well as how polymeric drug delivery and nanotechnology can be employed to optimize drug penetration to both the anterior and posterior segment of the eye.

Inhibition of vascular endothelial growth factor A expression in mouse granulosa cells by lentivector-mediated RNAi

Vascular endothelial growth factor (VEGF) has been found responsible for the induction of proliferation and differentiation in granulosa cells. We constructed four short hairpin RNA (shRNA) expression plasmids targeting the mouse VEGFA gene, and examined their effect on VEGF expression in mouse granulosa cells (MGC) in vitro. Four different shRNA oligonucleotides targeting the coding sequence of mouse VEGFA mRNA and one negative control (shNC) were designed and cloned into a pGPU6/GFP/Neo siRNA expression vector, and transiently transfected into MGC. At 48 h post-transfection, total RNA was extracted from the cells and subjected to qRT-PCR analysis. The most effective interference vector, shVEGF1487 was chosen for lentiviral construction. The recombinant plasmid was then transfected into 293FT cells via Lipofectamine(TM) 2000-mediated gene transfer, for the production of lentivirus, and then concentrated via ultracentrifugation. This lentiviral vector was then used for the transduction of MGC. VEGFA gene expression, apoptosis genes and VEGFA receptor genes were detected by qRT-PCR, the VEGFA protein level in culture media by ELISA assay and protein levels in MGC by Western blot analysis. The four VEGFA expression plasmids were successfully constructed and the most effective interference vector, shVEGF1487, was chosen for lentiviral production and MGC transduction. There was significant knockdown of the VEGFA gene, receptor genes and apoptosis genes for all the shVEGF constructs, compared with the shNC and Mock controls. The lentiviral vector also gave significant knockdown of the VEGFA gene. Protein levels were lower for most of the shVEGFs based on Western blot analysis with exception of VEGF1359; in this case, it was higher than shNC but lower than for the Mock group. Lentivector-transduced MGC also gave lower levels of protein. We conclude that shVEGF expression plasmids and lentivector carrying RNAi are promising tools for the inhibition of VEGF, the corresponding receptor genes, and apoptosis gene expression in MGC.

Doxycycline-regulated growth hormone gene expression system for swine

Although growth hormone gene transgenic animals are much larger than normal animals, they manifest differences that have adverse effects on survival due to overexpression of growth hormone. We developed a stable pig embryonic fibroblast cell line expressing pig growth hormone (pGH) using the Tet-On system, with which we can conditionally manipulate expression of pGH in vivo. Inducible expression of pGH was achieved by combining reserve Tet-controlled transcriptional activator and tetracycline-responsive element in a single plasmid. The mRNA expression of pGH was significantly increased compared to the non-induced group by about 10-fold. The controlled secretion of pGH induced by doxycycline was further tested in stably transfected cells. We conclude that inducible GH expression can be achieved in pig embryonic fibroblasts.

Expression of protease-activated receptor-2 by osteoblasts

Osteoblasts express protease-activated receptor-1 (PAR-1), which is activated by thrombin or by synthetic peptides corresponding to the new "tethered ligand" N-terminus of PAR-1 created by receptor cleavage. Both thrombin and human PAR-1-activating peptide stimulate an elevation of [Ca2+]i in the human SaOS-2 osteoblast-like cell line, but the peptide stimulates receptor-mediated Ca+ entry, whereas thrombin does not. Stimulation of proliferation in rat primary osteoblast-like cells is greater in response to rat PAR-1-activating peptide than to thrombin. Because the PAR-1-activating peptides are now known to activate PAR-2, the current study was undertaken to investigate whether osteoblasts express this receptor and, if so, whether this could account for the observed discrepancies between responses of osteoblasts to thrombin and to PAR-1-activating peptides. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemical studies demonstrated expression of PAR-2 by primary cultures of rat calvarial osteoblast-like cells. In immunohistochemical studies of embryonic mouse bones, osteoblasts showed positive staining for the presence of PAR-2. Activators of PAR-2 include trypsin, mast cell tryptase, gingipain-R, and synthetic peptides corresponding to the PAR-2 tethered ligand sequence. Treatment of primary rat osteoblast-like cells with rat PAR-2-activating peptide (SLIGRL), or SaOS-2 cells with human PAR-2-activating peptide (SLIGKV), caused a dose-dependent increase in [Ca2+]i. Trypsin or gingipain-R also induced an increase in intracellular calcium concentration, and caused reciprocal cross desensitization. Activators of PAR-2 caused a sharp peak in [Ca2+]i followed by a sustained plateau; [Ca2+]i returned to baseline levels upon treatment with ethylene-glycol tetraacetic acid (EGTA). Treatment of rat osteoblast-like cells in vitro with SLIGRL did not affect thymidine incorporation or endogenous alkaline phosphatase activity. The results presented here demonstrate that osteoblasts express PAR-2, and that such expression is able to account for the observed discrepancies between thrombin and PAR-1-activating peptides in their ability to evoke calcium entry, but not proliferative responses.