Enhancement of Corneal Visibility in Optical Coherence Tomography Images Using Corneal Adaptive Compensation

PURPOSE

To improve the contrast of optical coherence tomography (OCT) images of the cornea (post processing).

METHODS

We have recently developed standard compensation (SC) algorithms to remove light attenuation artifacts. A more recent approach, namely adaptive compensation (AC), further limited noise overamplification within deep tissue regions. AC was shown to work efficiently when all A-scan signals were fully attenuated at high depth. But in many imaging applications (e.g., OCT imaging of the cornea), such an assumption is not satisfied, which can result in strong noise overamplification. A corneal adaptive compensation (CAC) algorithm was therefore developed to overcome such limitation. CAC benefited from local A-scan processing (rather than global as in AC) and its performance was compared with that of SC and AC using Fourier-domain OCT images of four human corneas.

RESULTS

CAC provided considerably superior image contrast improvement than SC or AC did, with excellent visibility of the corneal stroma, low noise overamplification, homogeneous signal amplification, and high contrast. Specifically, CAC provided mean interlayer contrasts (a measure of high stromal visibility and low noise) greater than 0.97, while SC and AC provided lower values ranging from 0.38 to 1.00.

CONCLUSION

CAC provided considerable improvement compared with SC and AC by eliminating noise overamplification, while maintaining all benefits of compensation, thus making the corneal endothelium and corneal thickness easily identifiable.

TRANSLATIONAL RELEVANCE

CAC may find wide applicability in clinical practice and could contribute to improved morphometric and biomechanical understanding of the cornea.

Development of Selective Lamellar Keratoplasty within an Asian Corneal Transplant Program: The Singapore Corneal Transplant Study (An American Ophthalmological Society Thesis)

PURPOSE

To evaluate outcomes of anterior lamellar keratoplasty (ALK) and endothelial keratoplasty (EK) within the Singapore Corneal Transplant Study (SCTS), with the hypothesis that both ALK and EK are able to provide equivalent or improved clinical outcomes, compared to penetrating keratoplasty (PK), and to determine changing trends globally with other international databases.

METHODS

Clinical data on all transplants performed was derived from our SCTS database, a prospective national keratoplasty registry, and clinical outcomes (graft survival, endothelial cell loss, complications, visual acuity) were compared between PK, ALK, and EK. Global trends on indications and forms of keratoplasty performed in 2011/2012 were obtained from national keratoplasty or eye banking registries, corneal/ophthalmological societies, national eye banks, and national ophthalmic institutions.

RESULTS

Global rates of EK surgery vary widely, from 52% (Sweden) to 0% (South Africa), with higher adoption by industrialized countries. ALK adoption rates similarly vary from 28.7% (China) to 1.0% (Philippines). SCTS data show high adoption rates in Singapore: EK 44% and ALK 28%. Our surgical modifications to big-bubble deep anterior lamellar keratoplasty (DALK) surgery resulted in visual outcomes matching PK, and a low conversion to PK of 2.1%, whereas our evolving approaches to donor insertion in Descemet's stripping automated endothelial keratoplasty (DSAEK) show significant reduction in 1-year postoperative endothelial cell loss rates from 60% (folding), to 22% to 30% (Sheets Glide), to 15% (EndoGlide inserter).

CONCLUSION

Improvements in various forms of ALK and EK surgery can lead to better visual outcomes, longer graft survival, and reduced complications, as compared to PK. Global trends suggest adoption of these procedures at different rates.

Endothelial keratoplasty after failed penetrating keratoplasty: an alternative to repeat penetrating keratoplasty

PURPOSE

To analyze graft survival of endothelial keratoplasty (EK) under a previous failed penetrating keratoplasty (PK) compared to repeat PK.

DESIGN

Retrospective, comparative case series.

METHODS

Analysis involved consecutive patients who underwent either a repeat PK or EK under PK, after failed PK, whose primary surgical indication was pseudophakic bullous keratopathy at a single tertiary center. Clinical data and donor and recipient characteristics were recorded from our prospective cohort from the Singapore Corneal Transplant Study. Main outcome measure was graft survival up to 5 years follow-up.

RESULTS

We included a total of 113 eyes that underwent a repeat PK (n = 81) or EK under a failed PK (n = 32). Cumulative graft survival probabilities comparing repeat PK with EK under PK were at 91.9% vs 96.2% (1 year), 82.6% vs 91.6% (2 years), 66.8% vs 86.4% (3 years), and 51.3% vs 86.4% up to 5 years follow-up, respectively (log-rank P value = .013). Multivariate Cox regression analysis was performed, which adjusted for: age, sex, risk factors for graft failure (corneal neovascularization, ocular surface disease, glaucoma, active corneal inflammation, anterior synechiae), donor endothelial cell count, and repeat donor size. Repeat PK was a significant risk factor for graft failure compared to performing an EK under PK (hazard ratio: 10.17; 95% CI 1.10-93.63; P = .041).

CONCLUSION

In our study of eyes with bullous keratopathy, endothelial keratoplasty under a previously failed PK provided better graft survival outcomes than repeat PK, adjusting for potential confounders and risk factors for graft failure.

Manual small incision cataract surgery (MSICS) with posterior chamber intraocular lens versus extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens for age-related cataract

BACKGROUND

Age-related cataract is the opacification of the lens, which occurs as a result of denaturation of lens proteins. Age-related cataract remains the leading cause of blindness globally, except in the most developed countries. A key question is what is the best way of removing the lens, especially in lower income settings.

OBJECTIVES

To compare two different techniques of lens removal in cataract surgery: manual small incision surgery (MSICS) and extracapsular cataract extraction (ECCE).

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 8), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to September 2014), EMBASE (January 1980 to September 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to September 2014), Web of Science Conference Proceedings Citation Index- Science (CPCI-S), (January 1990 to September 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 23 September 2014.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) only. Participants in the trials were people with age-related cataract. We included trials where MSICS with a posterior chamber intraocular lens (IOL) implant was compared to ECCE with a posterior chamber IOL implant.

DATA COLLECTION AND ANALYSIS

Data were collected independently by two authors. We aimed to collect data on presenting visual acuity 6/12 or better and best-corrected visual acuity of less than 6/60 at three months and one year after surgery. Other outcomes included intraoperative complications, long-term complications (one year or more after surgery), quality of life, and cost-effectiveness. There were not enough data available from the included trials to perform a meta-analysis.

MAIN RESULTS

Three trials randomly allocating people with age-related cataract to MSICS or ECCE were included in this review (n = 953 participants). Two trials were conducted in India and one in Nepal. Trial methods, such as random allocation and allocation concealment, were not clearly described; in only one trial was an effort made to mask outcome assessors. The three studies reported follow-up six to eight weeks after surgery. In two studies, more participants in the MSICS groups achieved unaided visual acuity of 6/12 or 6/18 or better compared to the ECCE group, but overall not more than 50% of people achieved good functional vision in the two studies. 10/806 (1.2%) of people enrolled in two trials had a poor outcome after surgery (best-corrected vision less than 6/60) with no evidence of difference in risk between the two techniques (risk ratio (RR) 1.58, 95% confidence interval (CI) 0.45 to 5.55). Surgically induced astigmatism was more common with the ECCE procedure than MSICS in the two trials that reported this outcome. In one study there were more intra- and postoperative complications in the MSICS group. One study reported that the costs of the two procedures were similar.

AUTHORS' CONCLUSIONS

There are no other studies from other countries other than India and Nepal and there are insufficient data on cost-effectiveness of each procedure. Better evidence is needed before any change may be implemented. Future studies need to have longer-term follow-up and be conducted to minimize biases revealed in this review with a larger sample size to allow examination of adverse events.

Determinants of posterior corneal biometric measurements in a multi-ethnic Asian population

PURPOSE

To describe the corneal and anterior segment determinants of posterior corneal arc length (PCAL) and posterior corneal curvature (PCC).

METHODS

Cross-sectional, population-based study of 1069 subjects (1069 eyes) aged 40-80 years, from three major Asian ethnic groups. All underwent anterior segment optical coherence tomography imaging and analysis with Zhongshan Angle Assessment Program. Our main outcome measures were determinants of PCAL and PCC using adjusted, multivariate linear regression analysis, adjusted for confounders to obtain the estimated marginal means (EMM) with standard error (SE).

RESULTS

The overall mean (± SD) of PCC was: 6.51±0.39 mm; and PCAL was: 12.52±0.59 mm. Malays had a relatively longer PCAL (EMM = 12.74 mm, SE = 0.04 mm) than Chinese (EMM = 12.48 mm, SE = 0.03 mm, P<0.001), and Indians (EMM = 12.42 mm, SE = 0.03 mm, P<0.001). Anterior segment parameters had weak-moderate correlations with PCAL, which included: anterior chamber depth (ACD) (r = 0.55, P<0.001), PCC (r = 0.27, P<0.001), anterior corneal curvature (ACC) (r = 0.14, P<0.001) and central corneal thickness (CCT) (r = -0.07, P = 0.023). In multivariate analysis, anterior segment parameters explained only 37.6% of the variance of PCAL, with ACD being the most important determinant (partial R2  = 0.300; P<0.001). The determinants of PCC included ACC, PCAL and CCT (explaining 72.1% variation of PCC), with ACC being the most important determinant (partial R2  = 0.683; P<0.001).

CONCLUSION

There was moderate correlation of PCAL with ACD, but anterior segment parameters accounted for only a small proportion of the variation in PCAL. The significant differences in PCAL and PCC amongst different Asian ethnic groups suggests that there is a need to consider this factor when planning for anterior segment surgeries such as endothelial keratoplasty.

Comparison of a donor insertion device to sheets glide in Descemet stripping endothelial keratoplasty: 3-year outcomes

PURPOSE

To compare 3-year endothelial cell loss and graft survival following Descemet stripping automated endothelial keratoplasty (DSAEK) using the EndoGlide (AngioTech, Reading, Pennsylvania, USA/Network Medical Products, North Yorkshire, UK) donor insertion device compared to donor insertion using the Sheets glide technique.

DESIGN

Retrospective comparative case series.

METHODS

Study involved consecutive patients who underwent DSAEK with Fuchs endothelial dystrophy or pseudophakic bullous keratopathy at a single tertiary center. Clinical data with outcomes and donor and recipient characteristics were obtained from our ongoing prospective cohort from the Singapore Corneal Transplant Study. Main outcome measures were percent endothelial cell loss and graft survival up to 3 years.

RESULTS

Overall percent endothelial cell loss was significantly lower in the EndoGlide group (100 eyes) compared to the Sheets glide group (119 eyes) at 1 year (16.3% ± 16.6% vs 29.5% ± 22.2%, P < .001), 2 years (23.8% ± 17.8% vs 35.7% ± 22.9%, P = .001), and 3 years (29.7% ± 20.9% vs 38.5% ± 24.1%, P = .015) postoperatively. Overall graft survival was greater in the EndoGlide compared to Sheets glide group up to 3 years postoperatively (97.9% vs 86.5%, log-rank P value = .005). In eyes with Fuchs endothelial dystrophy, endothelial cell loss was significantly lower in the EndoGlide group (3-year: 28.2% ± 17.9% vs 43.4% ± 27.1%, P = .032). In eyes with pseudophakic bullous keratopathy, the EndoGlide group had a superior graft survival compared to Sheets glide (log-rank P = .031).

CONCLUSION

Endothelial cell loss was lower using a donor insertion device during DSAEK, compared to using the Sheets glide technique for DSAEK, in Asian eyes with Fuchs endothelial dystrophy, and resulted in better graft survival in eyes with pseudophakic bullous keratopathy.

Health burden associated with visual impairment in Singapore: the Singapore epidemiology of eye disease study

OBJECTIVE

To assess the impact of visual impairment (VI) on health-related quality of life and to compare the health burden of VI and other health conditions in Singapore.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

We studied the 10 009 adults (3353 Chinese, 3397 Indians, and 3259 Malays) who underwent a comprehensive eye assessment and completed the European Quality of Life-5 Dimensions (EQ-5D) questionnaire in the Singapore Epidemiology of Eye Disease Study.

METHODS

We estimated the effects of VI, obesity, hypertension, diabetes, and hyperlipidemia on the EQ-5D index score using linear regression models and the association between VI and self-reported EQ-5D health problems using logistic regression models. We compared prevalence-based quality-adjusted life-year (QALY) loss associated with VI and other health conditions. For each condition, QALY loss was calculated for 100 000 persons in 1 year using associated reduction in EQ-5D index score estimated in regression analysis as disutility.

MAIN OUTCOME MEASURES

The EQ-5D index score and annual QALY loss.

RESULTS

The EQ-5D index score decreased with increasing VI severity in all 3 ethnicities. For example, after adjusting for sociodemographic characteristics, the difference in EQ-5D index score between adults with bilateral severe VI and those without VI was -0.044 (95% confidence interval [CI], -0.089 to 0.001) in Chinese, -0.127 (95% CI, -0.237 to -0.017) in Indians, and -0.085 (95% CI, -0.148 to -0.022) in Malays. In all 3 ethnicities, VI was associated with reporting of problems in mobility (e.g., odds ratio [OR], 3.69 for Chinese with bilateral severe VI; 95% CI, 1.21-12.13) and usual activities (e.g., OR, 6.51 for Chinese with bilateral severe VI; 95% CI, 1.59-26.58). In Indians, VI was also associated with anxiety or depression (e.g., OR, 2.68 for bilateral severe VI; 95% CI, 1.11-6.50). The annual QALY loss associated with VI was 511.8 in Chinese, 608.8 in Indians, and 706.7 in Malays, greater than that associated with other health conditions examined in this study.

CONCLUSIONS

Visual impairment is associated with substantial health burden among Asians in Singapore. The relatively high burden of VI highlights the importance of VI prevention. The ethnic difference exhibited in this burden warrants further study.

Descemet's stripping automated endothelial keratoplasty with anterior chamber intraocular lenses: complications and 3-year outcomes

PURPOSE

To describe outcomes and complications following Descemet's stripping automated endothelial keratoplasty (DSAEK) in eyes with pseudophakic bullous keratopathy (BK) while retaining the anterior chamber intraocular lenses (ACIOL).

METHODS

We included consecutive patients who underwent DSAEK for BK at a single tertiary centre from 1 January 2008 to 1 April 2010, from our prospective cohort (Singapore Corneal Transplant Study). We compared eyes with BK, which underwent DSAEK while retaining ACIOL (n=18), to those with DSAEK alone with the posterior chamber intraocular lenses left in place as a comparison group (n=114). Main outcome measures were endothelial cell (EC) loss and graft survival.

RESULTS

The percentage EC loss at 1 year was 31.9±21.3% in the DSAEK with ACIOL group compared to 24.5±21.2% in the DSAEK group (p=0.516); however, this figure was significantly greater in the DSAEK with ACIOL group at 3 years compared to the DSAEK group (55.3±29.2% vs 33.3±20.8%; p=0.01 respectively). Graft survival was also significantly poorer in the DSAEK ACIOL group compared to the DSAEK group over 3 years (log rank p=0.002).

CONCLUSIONS

We found that although eyes with BK and ACIOL that underwent DSAEK while retaining the ACIOL suffered EC loss which was not significantly greater at 1 year, EC loss and graft survival were significantly poorer compared to DSAEK controls at 3 years postoperatively.

Ethnic variation in central corneal refractive power and steep cornea in Asians

PURPOSE

To describe ethnic differences in the distribution of central corneal refractive power and steep cornea in a multiethnic Asian population.

METHODS

A total of 2968 Chinese, 2957 Indian and 2928 Malay participants aged over 40 years were included in this study. Each subject underwent standardized systematic and ocular examinations, interviewer-administered questionnaires, and blood investigations for risk factor assessment. Central corneal refractive power was measured using an autorefractor. Steep cornea was defined as central corneal refractive power exceeding 48 diopters (D) measured by keratometry.

RESULTS

Mean keratometry readings were 43.9 ± 1.5 D in Malays, 44.2 ± 1.5 D in Indians and 43.9 ± 1.5 D in Chinese. The prevalence of steep cornea was 0.6% (95% confidence interval, CI, 0.3-0.9%) in Malays, 1.0% (95% CI 0.7-1.4%) in Indians and 0.5% (95% CI 0.3-0.8%) in Chinese. In multivariate analysis, increasing central corneal refractive power was associated with Indian race, shorter body height, non-smokers, absence of pterygium, shorter axial length, thinner corneas and greater anterior chamber depth, while the presence of steep cornea was significantly associated with Indian race, shorter axial length and thinner corneas.

CONCLUSIONS

Indian participants had the steepest corneas among the three major ethnic groups in Singapore. Central corneal refractive power was related to several ocular parameters including anterior chamber depth, axial length and central corneal thickness. These data have important clinical implications for understanding the risk of keratoconus.

A new design and application of bioelastomers for better control of intraocular pressure in a glaucoma drainage device

Glaucoma drainage device (GDD) implantation is an effective method of lowering the intraocular pressure (IOP). Commonly used GDDs can be classified into nonvalved and valved. Although a stable IOP is critical, currently available devices often cause extreme IOP fluctuations: nonvalved GDDs suffer from a risk of hypotony (IOP<5 mmHg), whereas valved GDDs have a higher risk ocular hypertensive (IOP>22 mmHg). It is hypothesized that a GDD with a valve designed to open around the time of onset of the hypertensive phase, would minimize IOP fluctuation. Accordingly, a valve fabricated from a biodegradable polymer poly(L-lactide-co-ϵ-caprolactone) (PLC 70/30) is evaluated in vitro and in vivo. The pressure response is compared with its non-degradable counterpart in in vitro studies of IOP. It is also established that in vitro, the biodegradability of the valve is programmed to occur over 12 weeks. In vivo, a steady and low IOP is achieved with the biodegradable valve and the hypertensive phase is significantly attenuated compared with the commercial device. Fibrotic encapsulation of the device is also minimized with the biodegradable valve in vivo.

Intraoperative anterior segment optical coherence tomography: a novel assessment tool during deep anterior lamellar keratoplasty

PURPOSE

To describe the use of high-resolution anterior segment optical coherence tomography (AS-OCT) during deep anterior lamellar keratoplasty (DALK).

DESIGN

Prospective case series.

METHODS

At the Singapore National Eye Centre we performed sequential intraoperative AS-OCT scans using iVue 100-2 (Optovue, Fremont, CA, USA) during various DALK techniques.

RESULTS

In case 1 (corneal scarring) the OCT images helped to guide manual dissection, showed the depth of the needle track before air injection, and identified the location of a small bubble when the big bubble failed. In cases 2 (macular dystrophy) and 3 (lattice), viscodissection was undertaken, but in case 2 the OCT showed the viscoelastic trapped intrastromally, compared to case 3, in which the viscobubble dissection was successful. In case 4 (irregular corneal thinning and scarring), AS-OCT enabled accurate decision on initial trephination and guided dissection. In case 5 (keratoconus), the OCT showed the achieved big-bubble and detached Descemet membrane. Case 6 was a repeat DALK; the OCT guided the manual dissection of the residual stroma underlying the failed graft. In case 7, the OCT showed an intrastromal retention of fluid that was not detectable by the operating microscope due to diffuse scarring following alkaline injury. The OCT helped to assess the location of the Descemet membrane and guided the manual dissection.

CONCLUSIONS

Intraoperative high-definition AS-OCT obtained good-quality images of the cornea during DALK and proved useful in various cases of DALK to help the surgeon decide on a number of surgical steps.

Sustained drug release in nanomedicine: a long-acting nanocarrier-based formulation for glaucoma

Therapeutic nanomedicine has concentrated mostly on anticancer therapy by making use of the nanosize for targeted therapy. Such nanocarriers are not expected to have sustained release of the bioactive molecule beyond a few days. There are other conditions where patients can benefit from sustained duration of action following a single instillation, but achieving this has been difficult in nanosized carriers. An important prerequisite for sustained delivery over several months is to have sufficiently high drug loading, without disruption or changes to the shape of the nanocarriers. Here we report on successful development of a drug-encapsulated nanocarrier for reducing intraocular pressure in a diseased nonhuman primate model and explain why it has been possible to achieve sustained action in vivo. The drug is a prostaglandin derivative, latanoprost, while the carrier is a nanosized unilamellar vesicle. The mechanistic details of this unique drug-nanocarrier combination were elucidated by isothermal titration calorimetry. We show, using Cryo-TEM and dynamic light scattering, that the spherical shape of the liposomes is conserved even at the highest loading of latanoprost and that specific molecular interactions between the drug and the lipid are the reasons behind improved stability and sustained release. The in vivo results clearly attest to sustained efficacy of lowering the intraocular pressure for 120 days, making this an excellent candidate to be the first truly sustained-release nanomedicine product. The mechanistic details we have uncovered should enable development of similar systems for other conditions where sustained release from nanocarriers is desired.

A cluster randomised controlled trial evaluating an incentive-based outdoor physical activity programme to increase outdoor time and prevent myopia in children

PURPOSE

To evaluate an incentive-based intervention to increase time spent outdoors among children in a 9-month cluster randomised controlled trial.

METHODS

Two hundred and eighty-five children aged 6-12 years of age were randomised to the intervention (n = 147) or control arm (n = 138) in the Family incentive trial (FIT). The FIT intervention comprised of targeted education on myopia and good eye care habits, structured weekend outdoor activities and incentives for children to increase their daily steps via pedometers. The main outcome measure was outdoor time, measured by the WHO questionnaire and a 1-week diary.

RESULTS

Interim analysis at 6 months showed a significant increase in mean outdoor time per week in the intervention arm (14.75 h week(-1) ) compared to the control arm (12.40 h week(-1) ) as measured by the questionnaire (p = 0.04). However, greater outdoor time was not statistically significant at the end of the trial (15.95 h week(-1) vs 14.34 h in the control group (p = 0.29).

CONCLUSIONS

There was an increase in outdoor time for children in the incentive-based physical activity outdoor program after 6 months but not at the end of the trial. Further larger school trials with better compliance with the intervention and longer duration could be conducted to evaluate clinical outcomes such as myopic shifts.

IgE-mediated food allergy--diagnosis and management in New Zealand children

AIM

To summarise the diagnosis and management of IgE-mediated food allergy (FA) in New Zealand children.

METHOD

A review of the scientific literature and subsequent consensus development.

RESULTS

FA is a common problem in New Zealand children with management necessitating accurate diagnosis, appropriate risk management, and reassessment over time.

CONCLUSION

This paper highlights the importance of a structured approach to diagnosis and management of FA in New Zealand children, guided by appropriately skilled health professionals.

Outcomes of corneal transplantation for irreversible corneal decompensation secondary to corneal endotheliitis in Asian eyes

PURPOSE

To describe outcomes of corneal transplantation for irreversible corneal decompensation from corneal endotheliitis in Asian eyes.

DESIGN

Retrospective, observational case series.

METHODS

We reviewed consecutive patients with corneal endotheliitis (32 eyes of 31 subjects) who underwent keratoplasty (January 1, 2008-December 1, 2009). All eyes had preoperative aqueous polymerase chain reaction (PCR) analysis for viruses, including cytomegalovirus (CMV). CMV-positive patients were treated preoperatively with topical corticosteroids and anti-CMV treatment (oral valganciclovir 900 mg twice daily, topical ganciclovir 0.15% 5 applications per day, for 6 weeks) with complete resolution of ocular inflammation, and quiescence for at least 6 months before corneal transplantation. Our main outcome measure was recurrence of endotheliitis within 1 year after corneal transplantation.

RESULTS

Five eyes were CMV positive; the remaining 27 eyes were negative for all viruses on PCR analysis. CMV-positive patients had a higher rate of recurrence of endotheliitis within 1 year after corneal transplantation, compared with CMV-negative eyes (60% vs 7.4%, P = .01). The CMV-positive eyes had recurrent endotheliitis at a median of 10 months (range 3-11 months) after corneal transplantation. After successful anti-CMV treatment, all 5 CMV-positive eyes then continued to have clear grafts for a median duration of 21 months (range 13-44 months).

CONCLUSION

Our study suggests that Asian patients with corneal endotheliitis may benefit from preoperative aqueous PCR analysis before corneal transplantation. Such patients were more likely to have a recurrence of endothelial inflammation if they were CMV positive preoperatively, despite successful anti-CMV treatment before surgery.

Comparison of anterior segment optical tomography parameters measured using a semi-automatic software to standard clinical instruments

Objective

To compare anterior segment parameters measured using a semi-automatic software (Zhongshan Angle Assessment Program, ZAP) applied to anterior segment optical coherence tomography (AS-OCT) images, with commonly used instruments.

Methods

Cross-sectional study of a total of 1069 subjects (1069 eyes) from three population-based studies of adults aged 40–80 years. All subjects underwent AS-OCT imaging and ZAP software was applied to determine anterior chamber depth (ACD), central corneal thickness (CCT), anterior and keratometry (K) – readings. These were compared to auto-refraction, keratometry and ocular biometry measured using an IOLMaster, ultrasound pachymeter and auto-refractor respectively. Agreements between AS-OCT (ZAP) and clinical instrument modalities were described using Bland-Altman, 95% limits of agreement (LOA).

Results

The mean age of our subjects was 56.9±9.5 years and 50.9% were male. The mean AS-OCT (ZAP) parameters of our study cohort were: ACD 3.29±0.35 mm, CCT 560.75±35.07 µm; K-reading 46.79±2.72 D. There was good agreement between the measurements from ZAP analysis and each instrument and no violations in the assumptions of the LOA; albeit with a systematic bias for each comparison: AS-OCT consistently measured a deeper ACD compared to IOLMaster (95% LOA −0.24, 0.55); and a thicker CCT for the AS-OCT compared to ultrasound pachymetry (16.8±0.53 µm 95% LOA −17.3, 50.8). AS-OCT had good agreement with auto-refractor with at least 95% of the measurements within the prediction interval (P value <0.001).

Conclusion

This study demonstrates that there is good agreement between the measurements from the AS-OCT (ZAP) and conventional tools. However, small systematic biases remain that suggest that these measurement tools may not be interchanged.

Aqueous cytokine changes associated with Posner-Schlossman syndrome with and without human cytomegalovirus

AIM

To study the differences in aqueous cytokines in Posner-Schlossman Syndrome (PSS) patients with and without human cytomegalovirus (CMV) DNA in the aqueous humor.

METHODS

This is a prospective study. Fifty-three uveitis patients with clinical signs of PSS were enrolled and aqueous humor samples were collected. Fourteen PSS patients were positive of CMV DNA in the aqueous by polymerase chain reaction (PCR) analysis. These eyes were negative of common ocular pathogens such as herpes simplex virus, varicella-zoster virus, rubella virus and toxoplasma. Twenty-five otherwise healthy cataract patients were enrolled as controls. Cytokine concentration was measured by a magnetic color-bead-based multiplex assay and analyzed using statistical and classification approaches.

RESULTS

The average age of 53 PSS patients was 48.74±13.43 years (yrs) (mean ± standard deviation) and 66.3±15.0 yrs for the controls. The median CMV viral DNA copy number was 26000/mL aqueous (range 1400 to 85000 copies/mL) in 14 CMV positive patients as determined by quantitative PCR. PSS aqueous had significantly higher Interleukin (IL)-8 (CXCL8), monocyte chemotactic protein-1 (CCL2), macrophage inhibitory protein 1-β (CCL4), granulocyte colony-stimulating factor (GCSF) and transforming growth factor-β (TGF-β) levels than controls after adjusted by age and gender. IL-2, IL-12, tumor necrosis factor-α (TNF-α) and interferon-α (IFN-α) levels were significantly lower in PSS aqueous than controls. No difference between CMV positive PSS and CMV negative PSS aqueous was observed. Over 97% of PSS samples were distinguished from controls by elevated CXCL10 (>500 ng/mL), CXCL8 (>30 ng/mL) and CCL2 (>60 ng/mL) levels.

CONCLUSION

PSS eyes were characterized by elevated aqueous chemokine concentration. The presence of CMV viral DNA was not associated with significant change of the type of cytokine expression in PSS patients.

Multifocal photodynamic therapy for diffuse choroidal hemangioma

BACKGROUND

A choroidal hemangioma is an uncommon benign vascular tumor of the choroid that can be either circumscribed or diffuse. In our experience, diffuse choroidal hemangiomas in Asian patients often require multiple photodynamic therapy (PDT) treatment sessions.

METHODS

We here provide a case report of a 7-year-old boy with Sturge-Weber syndrome who presented with diffuse choroidal hemangioma in the left eye. Five sessions of PDT treatment were required over a period of 1 year and a final optical coherence tomogram 3 months later revealed resolution of subretinal fluid and the choroidal hemangioma.

RESULTS

Final visual acuity was 20/100 in the left eye with resolution of subretinal fluid. This case report illustrates that a single application of PDT using standard published parameters was insufficient to achieve the destruction of the enlarged vessels. This experience is similar to previous Chinese reports on circumscribed choroidal hemangiomas. The decision for repeat treatment was based on subretinal fluid recurrence, rather than complete tumor regression.

CONCLUSION

Our case report supports previous suggestions that larger dilated vessels in the vascular network of a choroidal hemangioma might affect the efficacy and selectivity of PDT in treating the eyes of Asian patients - which may explain the need for multiple treatments.

Steroid-induced ocular hypertension in Asian children with severe vernal keratoconjunctivitis

Background

We describe clinical characteristics and risk factors for corticosteroid response in children with severe vernal keratoconjunctivitis (VKC).

Design

Retrospective, noncontrolled, comparative case series.

Participants

Patients from three tertiary centers in Singapore.

Methods

We reviewed patients with severe VKC (clinical grade > 2) who were on topical steroid therapy, with a minimum follow-up period of 1 year post-presentation. Logistic regression was used to determine risk factors for corticosteroid response.

Main outcome measure

Corticosteroid response was defined as intraocular pressure (IOP) >21 mmHg (three consecutive readings), or a rise of more than 16 mmHg from baseline, after commencement of steroid therapy in the absence of other possible causes of raised IOP.

Results

Forty-one of 145 (28.3%) patients developed a corticosteroid response, of which eight (5.5%) progressed to glaucoma. The overall mean age of onset of VKC was 9.9 ± 4.4 years. Longer duration of corticosteroid use (OR, 5.06; 95% CI: 1.04–25.56; P = 0.45) and topical dexamethasone 0.01% (OR, 2.25; 95% CI: 1.99–5.08; P = 0.40) were associated with corticosteroid response. Mixed type of VKC (OR, 9.76; 95% CI: 3.55–26.77; P < 0.001), the presence of limbal neovascularization of ≥ three quadrants (OR, 6.33; 95% CI: 2.36–16.97; P < 0.001), and corneal involvement (OR, 3.51; 95% CI: 1.31–9.41; P = 0.012) were significant clinical risk factors after adjusting for potential confounders such as age, sex, ethnicity, duration, and type of corticosteroid used.

Conclusion

Children on long-term oral corticosteroids with severe, mixed-type VKC and corneal involvement are more likely to develop corticosteroid response, and may require early treatment to prevent progression to glaucoma.

Small incision lenticule extraction (SMILE) versus laser in-situ keratomileusis (LASIK): study protocol for a randomized, non-inferiority trial

Background

Small incision lenticule extraction or SMILE is a novel form of ‘flapless’ corneal refractive surgery that was adapted from refractive lenticule extraction (ReLEx). SMILE uses only one femtosecond laser to complete the refractive surgery, potentially reducing surgical time, side effects, and cost. If successful, SMILE could potentially replace the current, widely practiced laser in-situ keratomileusis or LASIK. The aim of this study is to evaluate whether SMILE is non-inferior to LASIK in terms of refractive outcomes at 3 months post-operatively.

Methods/Design

Single tertiary center, parallel group, single-masked, paired-eye design, non-inferiority, randomized controlled trial. Participants who are eligible for LASIK will be enrolled for study after informed consent. Each participant will be randomized to receive SMILE and LASIK in each eye. Our primary hypothesis (stated as null) in this non-inferiority trial would be that SMILE differs from LASIK in adults (>21 years old) with myopia (> −3.00 diopter (D)) at a tertiary eye center in terms of refractive predictability at 3 months post-operatively. Our secondary hypothesis (stated as null) in this non-inferiority trial would be that SMILE differs from LASIK in adults (>21 years old) with myopia (> −3.00 D) at a tertiary eye center in terms of other refractive outcomes (efficacy, safety, higher-order aberrations) at 3 months post-operatively. Our primary outcome is refractive predictability, which is one of several standard refractive outcomes, defined as the proportion of eyes achieving a postoperative spherical equivalent (SE) within ±0.50 D of the intended target. Randomization will be performed using random allocation sequence generated by a computer with no blocks or restrictions, and implemented by concealing the number-coded surgery within sealed envelopes until just before the procedure. In this single-masked trial, subjects and their caregivers will be masked to the assigned treatment in each eye.

Discussion

This novel trial will provide information on whether SMILE has comparable, if not superior, refractive outcomes compared to the established LASIK for myopia, thus providing evidence for translation into clinical practice.

Trial registration

Clinicaltrials.gov NCT01216475.

Vacuolating cytotoxin and variants in Atg16L1 that disrupt autophagy promote Helicobacter pylori infection in humans

BACKGROUND & AIMS

The Helicobacter pylori toxin vacuolating cytotoxin (VacA) promotes gastric colonization, and its presence (VacA(+)) is associated with more-severe disease. The exact mechanisms by which VacA contributes to infection are unclear. We previously found that limited exposure to VacA induces autophagy of gastric cells, which eliminates the toxin; we investigated whether autophagy serves as a defense mechanism against H pylori infection.

METHODS

We investigated the effect of VacA on autophagy in human gastric epithelial cells and primary gastric cells from mice. Expression of p62, a marker of autophagy, was also assessed in gastric tissues from patients infected with toxigenic (VacA(+)) or nontoxigenic strains. We analyzed the effect of VacA on autophagy in peripheral blood monocytes obtained from subjects with different genotypes of ATG16L1, which regulates autophagy. We performed genotyping for ATG16L1 in 2 cohorts of infected and uninfected subjects.

RESULTS

Prolonged exposure of human gastric epithelial cells and mouse gastric cells to VacA disrupted induction of autophagy in response to the toxin, because the cells lacked cathepsin D in autophagosomes. Loss of autophagy resulted in the accumulation of p62 and reactive oxygen species. Gastric biopsy samples from patients infected with VacA(+), but not nontoxigenic strains of H pylori, had increased levels of p62. Peripheral blood monocytes isolated from individuals with polymorphisms in ATG16L1 that increase susceptibility to Crohn's disease had reduced induction of autophagy in response to VacA(+) compared to cells from individuals that did not have these polymorphisms. The presence of the ATG16L1 Crohn's disease risk variant increased susceptibility to H pylori infection in 2 separate cohorts.

CONCLUSIONS

Autophagy protects against infection with H pylori; the toxin VacA disrupts autophagy to promote infection, which could contribute to inflammation and eventual carcinogenesis.

Manual small incision cataract surgery (MSICS) with posterior chamber intraocular lens versus extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens for age-related cataract

BACKGROUND

Age-related cataract is the opacification of the lens, which occurs as a result of denaturation of lens proteins. Age-related cataract remains the leading cause of blindness globally, except in the most developed countries. A key question is what is the best way of removing the lens, especially in lower income settings.

OBJECTIVES

To compare two different techniques of lens removal in cataract surgery: manual small incision surgery (MSICS) and extracapsular cataract extraction (ECCE).

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 1), MEDLINE (January 1950 to February 2012), EMBASE (January 1980 to February 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2012), Web of Science Conference Proceedings Citation Index- Science (CPCI-S), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 14 February 2012.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) only. Participants in the trials were people with age-related cataract. We included trials where MSICS with a posterior chamber intraocular lens (IOL) implant was compared to ECCE with a posterior chamber IOL implant.

DATA COLLECTION AND ANALYSIS

Data were collected independently by two authors. We aimed to collect data on presenting visual acuity 6/12 or better and best-corrected visual acuity of less than 6/60 at three months and one year after surgery. Other outcomes included intraoperative complications, long-term complications (one year or more after surgery), quality of life, and cost-effectiveness. There were not enough data available from the included trials to perform a meta-analysis.

MAIN RESULTS

Three trials randomly allocating people with age-related cataract to MSICS or ECCE were included in this review (n = 953 participants). Two trials were conducted in India and one in Nepal. Trial methods, such as random allocation and allocation concealment, were not clearly described; in only one trial was an effort made to mask outcome assessors. The three studies reported follow-up six to eight weeks after surgery. In two studies, more participants in the MSICS groups achieved unaided visual acuity of 6/12 or 6/18 or better compared to the ECCE group, but overall not more than 50% of people achieved good functional vision in the two studies. 10/806 (1.2%) of people enrolled in two trials had a poor outcome after surgery (best-corrected vision less than 6/60) with no evidence of difference in risk between the two techniques (risk ratio (RR) 1.58, 95% confidence interval (CI) 0.45 to 5.55). Surgically induced astigmatism was more common with the ECCE procedure than MSICS in the two trials that reported this outcome. In one study there were more intra- and postoperative complications in the MSICS group. One study reported that the costs of the two procedures were similar.

AUTHORS' CONCLUSIONS

There are no other studies from other countries other than India and Nepal and there are insufficient data on cost-effectiveness of each procedure. Better evidence is needed before any change may be implemented. Future studies need to have longer-term follow-up and be conducted to minimize biases revealed in this review with a larger sample size to allow examination of adverse events.

Prevalence of and racial differences in pterygium: a multiethnic population study in Asians

PURPOSE

To describe the prevalence and risk factors of pterygium in a multiethnic Asian population and to examine racial differences.

DESIGN

Population-based study in Singapore, located 1° north of the equator.

PARTICIPANTS

Data were analyzed from 8906 participants from 3 population-based studies of Malays, Indians, and Chinese persons 40 years of age and older conducted between 2004 and 2011.

METHODS

Standardized slit-lamp examinations were performed by trained study ophthalmologists to examine the anterior segment for evidence of pterygium. Every subject underwent standardized systemic and ocular examinations, interviewer-administered questionnaires, and blood investigations for risk factor assessment. Regression and principle component analysis models were constructed to study the relationship of race and other factors to pterygium.

MAIN OUTCOME MEASURES

Any pterygium and severe (grade 3 or opaque) pterygium.

RESULTS

The overall prevalence of any pterygium was 10.1% (n = 900), of which severe pterygium was seen in 1.6% (n = 142). The prevalence of any pterygium was more common in Malays (15.5%) than Chinese (7.0%; P<0.001) or Indians (7.0%; P<0.001). Multivariate analysis revealed increasing age (P<0.001), male gender (P<0.001), Malay race (P<0.001), and having a poorer education level (P<0.001) as significant factors for any pterygium. Race contributed significantly to presence of any pterygium (41%; P<0.001) or presence in both eyes (33%; P<0.001) compared with other risk factors. Severe pterygium was associated with outdoor occupation (P = 0.02), but race was not a significant risk factor in multivariate analysis.

CONCLUSIONS

This population-based study in Asian persons of different races living in the same geographical location at the equator indicated that race is a significant risk factor for pterygium, with Malays having higher prevalence than Indians and Chinese, while controlling for other risk factors.

Comparison of aqueous humor cytokine and chemokine levels in diabetic patients with and without retinopathy

PURPOSE

To compare the aqueous humor levels of proinflammatory and angiogenic factors of diabetic patients with and without retinopathy.

METHODS

Aqueous humor was collected at the start of cataract surgery from diabetic subjects and non-diabetic controls. The presence and severity of diabetic retinopathy were graded with fundus examination. Levels of 22 different inflammatory and angiogenic cytokines and chemokines were compared.

RESULTS

Aqueous humor samples from 47 diabetic patients (20 without retinopathy, 27 with retinopathy) and 24 non-diabetic controls were included. Interleukin (IL)-2, IL-10, IL-12, interferon-alpha (IFN-α), and tumor necrosis factor (TNF)-α were measurable in significantly fewer diabetic samples, and where measurable, were at lower levels than in non-diabetic controls. IL-6 was measurable in significantly more diabetic samples, and the median levels were significantly higher in the eyes with retinopathy than the eyes without retinopathy and the non-diabetic eyes. The vascular endothelial growth factor (VEGF) level was significantly higher in the diabetic eyes with and without retinopathy compared to the non-diabetic controls. The IL-6 level positively correlated with the monocyte chemotactic protein-1 (CCL2) and interleukin-8 (CXCL8) levels and negatively with the TNF-α level. The VEGF level negatively correlated with the IL-12 and TNF-α levels.

CONCLUSIONS

The aqueous humor cytokine profile of diabetic patients without retinopathy was similar to that of patients with diabetic retinopathy. These cytokines may be useful biomarkers for early detection and prognosis of diabetic retinopathy. Compared to diabetic patients without retinopathy, only the IL-6 and VEGF levels were significantly higher in diabetic patients with retinopathy.

Comparison of aqueous humor cytokine and chemokine levels in diabetic patients with and without retinopathy

Background

Major-histocompatibility-complex class I-related chain A (MICA) antigens are the ligands of NKG2D, which is an activating or coactivating receptor expressed on human NK cells and CD8⁺T cells. We sought to determine whether MICA expression in human corneal epithelium (HCE) could affect the cytotoxicity mediated by NK cells or CD8⁺T cells.

Methods

Cell cultures of HCE were harvested from human donor eyes. Flow cytometric analysis and ELISA was performed to determine the levels of MICA expression on HCE. Then, HCE was transfected with a lentivirus vector expressing MICA and GFP. Flow cytometric analysis, RT-PCR, western blot and ELISA were performed to check the levels of MICA expression. For cytotoxicity testing, allogeneic NK cells and CD8⁺T cells were isolated from peripheral blood mononuclear cells of healthy volunteers by magnetic cell sorting. The cytolytic activity of NK cells and CD8⁺T cells was assessed against MICA-transfected HCE (NK cells: E:T ratio = 3:1; CD8⁺T cells: E:T ratio = 10:1) using the nonradioactive cytotoxicity detection kit lactate deshydrogenase.

Results

Surface expression of MICA on corneal epithelium was identified at a low level. A cell line of stable human MICA-transfected corneal epithelium was successfully established. Heightened expression of MICA on HCE was found to promote the cytotoxicity mediated by NK cells or CD8⁺T cells, which could be blocked by an anti-MICA antibody.

Conclusion

MICA molecules may contribute to cytotoxic responses mediated by activated immune effector cells in corneal epithelium immunity.

Endothelial cell counts after Descemet's stripping automated endothelial keratoplasty versus penetrating keratoplasty in Asian eyes

Background

The purpose of this study was to compare endothelial cell counts after Descemet’s stripping automated endothelial keratoplasty (DSAEK) and penetrating keratoplasty in Asian eyes.

Methods

This was a retrospective study of patients from our prospective Singapore Corneal Transplant Study cohort who received corneal transplantation in 2006–2008. We compared eyes that underwent DSAEK or penetrating keratoplasty for Fuchs’ endothelial dystrophy or pseudophakic and aphakic bullous keratopathy. Clinical data, and donor and recipient characteristics were recorded. Of 241 patients who met our inclusion criteria, 68 underwent DSAEK and 173 underwent penetrating keratoplasty. The main outcome measure was endothelial cell loss at 1 year. Secondary outcome measures were graft survival and visual outcomes at 1-year follow-up.

Results

There were no significant differences in baseline characteristics of patients between the treatment groups. Percent endothelial cell loss at 1-year follow-up was greater in penetrating keratoplasty eyes (40.9% ± 2.9%) compared with DSAEK eyes (22.4% ± 2.3%; P < 0.001). DSAEK-treated eyes had significantly superior uncorrected visual acuity (mean difference = 0.42 ± 0.0059; P < 0.001) and best spectacle-corrected visual acuity (mean difference = 0.14 ± 0.032; P < 0.001) as compared with penetrating keratoplasty-treated eyes. Penetrating keratoplasty-treated eyes had worse astigmatism as compared with DSAEK-treated eyes (−3.0 ± 2.1 versus −1.7 ± 0.8; P < 0.001). Graft survival at 1 year was comparable in both groups, ie, 66/68 (97.0%) DSAEK-treated eyes versus 158/173 (92.0%) of penetrating keratoplasty-treated eyes had clear grafts (P = 0.479).

Conclusion

We report lower percent endothelial cell loss comparing DSAEK and penetrating keratoplasty at 1-year follow-up in Asian eyes, with comparable graft survival rates in both groups.

Clinical signs of uveitis associated with latent tuberculosis

BACKGROUND

  To identify the clinical ocular signs of uveitis associated with latent tuberculosis.

DESIGN

  Retrospective case-control study.

PARTICIPANTS

  Consecutive patients from Singapore National Eye Centre Uveitis over 9 years. Sixty-two patients with uveitis associated with latent tuberculosis were compared with 72 matched controls diagnosed with other known uveitides.

METHODS

  Patients were categorized as: (A) predominantly anterior segment inflammation (anterior uveitides) and (B) predominantly posterior segment inflammation (intermediate, posterior or pan-uveitides). The diagnostic performance of combining these clinical signs with investigations such as interferon-gamma release assay positivity and chest X-ray results suggestive of pulmonary tuberculosis was done using area under the receiver operator characteristic curve.

MAIN OUTCOME MEASURES

  Sensitivity, specificity and likelihood of association with tuberculosis of various clinical signs.

RESULTS

  Extensive posterior synechiae and concomitant anterior scleritis in Group A; low-grade anterior chamber activity, retinal phlebitis and severe vitritis in Group B were significantly associated with latent tuberculosis. Combining these clinical signs with a positive interferon-gamma release assay and tuberculin skin test improved the diagnostic performance in both groups (area under the receiver operator characteristic curve for Group A = 0.779; Group B = 0.789).

CONCLUSION

  Patients with a combination of suggestive clinical signs with positive interferon-gamma release assay and tuberculin skin test are more likely to be accurately diagnosed with uveitis associated with latent tuberculosis, which responds to anti-tuberculosis therapy.

Aqueous cytokine and chemokine analysis in uveitis associated with tuberculosis

PURPOSE

The aim of this study was to study the aqueous cytokine and chemokine composition in patients with uveitis associated with tuberculosis (TAU).

METHODS

We present a prospective case series of consecutive new patients with active uveitis presenting at a single tertiary center (January 1, 2008-January 1, 2010). Patients with no ocular pathology other than cataracts were enrolled as non-inflammatory controls. Aqueous samples were taken from all study subjects and analyzed using a magnetic color-bead-based multiplex assay for cytokine and chemokine concentrations.

RESULTS

Twenty-five eyes of 25 patients with active uveitis with suspected tuberculosis (TB) and 23 non-inflammatory controls were enrolled. Ten patients tested positive on a tuberculin skin test and interferon-gamma release assay; all ten patients responded to anti-TB treatment with no recurrences (TAU). The remaining 15 eyes were negative for the above tests and had no other underlying causes for uveitis found on clinical evaluation and investigations; therefore, they were classified as "idiopathic uveitis" (IU). The TAU group showed significantly higher levels of interleukin-6 (IL-6; p=0.047), interleukin-8 (CXCL8; p=0.001), monokine induced by interferon-gamma (CXCL9; p=0.001), and interferon-gamma-induced protein 10 (IP-10 or CXCL10; p=0.002), compared to the controls. The IU group showed significantly higher levels of IL-6 (p=0.008), monocyte chemotactic protein-1 (CCL2; p=0.036), CXCL8 (p=0.001), and IL-9 (p=0.045), and significantly lower levels of IL-2 (p=0.011), IL-12 (p=0.001), and tumor necrosis factor (TNF)-α (p=0.001), compared to the controls. Heat map analysis revealed significant differences in aqueous cytokine and chemokine concentrations among the TAU patients, the IU patients, and the controls.

CONCLUSIONS

In our study population, aqueous cytokine and chemokine analyses suggest that subjects with uveitis associated with TB who respond to anti-TB therapy do not have an active ocular tuberculous infection, but rather an autoimmune-related ocular inflammation that may be triggered by TB.

Expression profile of inflammatory cytokines in aqueous from glaucomatous eyes

PURPOSE

To determine the proinflammatory cytokine profile of aqueous humor from glaucomatous eyes.

METHODS

Aqueous humor samples were prospectively collected from 38 eyes (26 primary open angle glaucoma [POAG] and 12 primary angle closure glaucoma [PACG] eyes) of 37 medically treated glaucoma patients and 23 cataract subjects recruited in an institutional setting in this case-controlled study. The main outcome measure was to quantify the levels of 29 inflammatory cytokines in the aqueous of glaucoma and cataract subjects using a multiplexed cytokine analysis. Data on patient demographics, duration of glaucoma, preoperative intraocular pressure (IOP) as well as duration of anti-glaucoma therapy were also collected for correlation analysis.

RESULTS

Mean duration of glaucoma was 53.8 months (range 1-360 months). Aqueous obtained from the glaucoma patients showed increased concentration of interleukin (IL)-9 (p=0.032), IL-12 (p=0.003), interferon (IFN)-α (p=0.034), IFN-γ (p=0.002), monokine induced by interferon-gamma (MIG or CXCL9) (p=0.006), and IL-10 (p=0.050), compared to the cataract group. The POAG group had higher IL-12 (p=0.011), IFN-γ (p=0.005), and CXCL9 (p=0.047) levels than controls, while the PACG group had higher interleukin-8 (CXCL8) (p=0.015) and CXCL9 (p=0.023) levels than the controls. No significant correlation was observed between aqueous cytokine level and preoperative IOP and duration of glaucoma. Duration of topical Timolol and Alphagan therapy correlated negatively with CXCL8 (r=-0.588, p=0.035), respectively.

CONCLUSIONS

Primary glaucoma is associated with an aqueous inflammatory response and this is different between POAG and PACG groups. Duration of glaucoma treatment may have an effect on cytokine profile in the aqueous.

Interferon-gamma release assay as a diagnostic test for tuberculosis-associated uveitis

BACKGROUND

To study the use of interferon-gamma release assay (IFN-γ) (IGRAs) as a diagnostic test for tuberculosis (TB)-associated uveitis (TAU).

DESIGN

Prospective cohort study.

PARTICIPANTS

Consecutive new patients (n=162) with clinical ocular signs suggestive of TAU, seen >1 year period at a single tertiary center.

METHODS

All subjects underwent investigations to rule out underlying disease, including T-SPOT.TB and tuberculin skin test (TST). Twenty-one subjects with underlying disease and three with interdeterminate T-SPOT.TB results were excluded. Those with T-SPOT.TB- or TST-positive results were referred to infectious diseases physician for evaluation. Anti-TB therapy (ATT) was prescribed if required. Patients' treatment response and recurrence were monitored for six months after completion of ATT, if given; or 1 year if no ATT was given.

MAIN OUTCOME MEASURE

Diagnosis of TAU.

RESULTS

Mean age of study cohort (n=138) was 46.8 ± 15.3 years. Majority were Chinese (n=80, 58.0%) and female (n=75, 54.3%). TST was more sensitive than T-SPOT.TB (72.0% vs 36.0%); but T-SPOT.TB was more specific (75.0% vs 51.1%) for diagnosing TAU. Patients with either a T-SPOT.TB (1.44; 95% confidence intervals (CI), 0.86-2.42) or TST (1.47; 95% CI, 1.12-1.94)-positive result are more likely to have TAU. The accuracy of diagnosing TAU increases when both tests are used in combination (area under the receiver operator curve=0.665; 95% CI, 0.533-0.795). Patients with both tests positive are 2.16 (95% CI, 1.23-3.80) times more likely to have TAU. Negative T-SPOT.TB or TST results do not exclude TAU (negative likelihood ratios <1.0).

CONCLUSIONS

We recommend using a combination of clinical signs, IGRA, and TST to diagnose TAU.

Anterior segment optical coherence tomography study of the cornea and anterior segment in adult ethnic South Asian Indian eyes

PURPOSE

To report normative results of anterior segment and corneal biometric parameters and their associations in ethnic South Asian Indian adults.

METHODS

The Singapore Indian Eye Study is a cross-sectional, population-based study of ethnic South Asian Indians ranging in age from 40 to 80 years. Subjects underwent ophthalmic and systemic examination, including imaging with anterior segment optical coherence tomography. Parameters were derived using the Zhongshan Assessment Program: anterior chamber depth (ACD), central corneal thickness (CCT), and anterior and posterior corneal curvatures (ACC and PCC). Posterior corneal arc length (PCAL) is a novel parameter defined as the arc distance between scleral spurs on the posterior border of the cornea. The authors studied correlations between PCAL with various anterior segment parameters and systemic parameters using univariate and multivariate analyses.

RESULTS

The authors studied 438 subjects whose mean age was 58.5 ± 9.9 years and of whom 50.7% were male. Parameters (mean ± SD) included central ACD 2.72 ± 0.37 mm, PCC 6.45 ± 0.35 mm, CCT 561.4 ± 34.1 μm, ACC 7.17 ± 0.35 mm, and PCAL 13.85 ± 0.54 mm. The authors found significant correlations between PCAL and ACD (r = 0.46, P < 0.001), PCC (r = 0.31, P < 0.001), and ACC (r = 0.16, P < 0.001), whereas they found poor correlations between PCAL and age, height, weight, blood pressure, and glucose levels. Multivariate analysis showed a significant association between PCAL and both ACD (P < 0.001) and PCC (P < 0.001).

CONCLUSIONS

The authors have described useful baseline anterior segment parameters from this population-based study of ethnic South Indian adults. These data may be useful for corneal and anterior segment procedures such as endothelial keratoplasty and anterior chamber intraocular lens insertion.

Nanomedicine for glaucoma: liposomes provide sustained release of latanoprost in the eye

Purpose:

To report the development and therapeutic evaluation of a liposomal nanocarrier for sustained release of latanoprost, in the rabbit eye.

Methods:

We fabricated latanoprost-loaded egg-phosphatidylcholine (EggPC) liposomes using the film hydration technique. The delivery vehicles were nano-sized (Z avg = 109 ± 18 nm), had a narrow poly dispersity index (PDI = 0.19 ± 0.04), and a very high loading efficiency (94% ± 5%). Based on in vitro data, we evaluated this formulation for lowering intraocular pressure (IOP) in rabbit eyes. Following a single subconjunctival injection of the latanoprost loaded formulation, the eyes were clinically monitored and the IOP recorded.

Results:

Latanoprost-loaded EggPC liposomes demonstrated a high drug/lipid mole ratio of 0.181, remained stable for at least 6 months on storage (4°C), and at least 1 month at 25°C. A slow and sustained release of 60% of latanoprost was achieved by 14 days in the in vitro release study. The same formulation demonstrated a greater sustained IOP lowering effect compared with daily administration of topical latanoprost beyond 90 days (4.8 ± 1.5 vs 2.5 ± 0.9 mmHg; P < 0.001). No signs of inflammation were evident in the eyes from slit-lamp examination analysis.

Conclusion:

The loading required for a long-term sustained delivery of latanoprost for up to 90 days in the rabbit eyes was achieved with EggPC liposomes. A single injection of latanoprost-loaded EggPC liposomes can lower the IOP for up to 90 days, with a greater IOP lowering effect than daily topical administration of latanoprost.

Corneal arcus is a sign of cardiovascular disease, even in low-risk persons

PURPOSE

To examine the association of corneal arcus to cardiovascular disease (CVD) in an adult, ethnic Indian population.

DESIGN

Population-based cross-sectional study.

METHODS

Population-based study of ethnic South Asian Indians 40 to 80 years of age in Singapore from June 2007 through March 2009. We obtained a 75.5% response rate (3397/4497). All participants underwent standardized interview and systemic and ocular examinations, followed by nonfasting blood sampling. Corneal arcus was detected using a standardized slit-lamp examination. The main outcome measure was CVD, defined from a self-reported history of previous myocardial infarction, angina, or stroke.

RESULTS

Corneal arcus, found in 1701 (50.1%) of 3397 participants, was associated with older age (odds ratio [OR], 3.07; 95% CI, 2.78 to 3.40; P < .001), male gender (OR, 2.17; 95% CI, 1.81 to 2.62; P < .001), higher levels of total cholesterol (OR, 1.14; 95% CI, 1.05 to 1.24; P = .002), hypertension (OR, 1.14; 95% CI, 1.05 to 1.24; P = .013), and cigarette smoking (OR, 1.59; 95% CI, 1.25 to 2.03; P < .001). Corneal arcus was associated with CVD (OR, 1.31; 95% CI, 1.02 to 1.7; P = .0038) independent of the above-named cardiovascular risk factors. Participants with low-risk Framingham scores were more likely to be associated with CVD if they had corneal arcus (men: OR, 2.02; 95% CI, 1.20 to 3.40; P = .008; women: OR, 2.78; 95% CI, 1.36 to 3.01; P < .001). Corneal arcus was associated with CVD independent of the Framingham score (men: Akaike information criterion, 1524.39 for Framingham Score and corneal arcus vs 1527.38 for Framingham Score alone; women: 1000.14 vs 1003.54, respectively).

CONCLUSIONS

Corneal arcus is associated with CVD, independent of risk factors in ethnic Indian adults, even in those at low risk for vascular disease.

Evaluation of sustained release of PLC-loaded prednisolone acetate microfilm on postoperative inflammation in an experimental model of glaucoma filtration surgery

PURPOSE

To evaluate the effect of a biodegradable microfilm with sustained release of prednisolone acetate (PA) on postoperative wound healing after experimental glaucoma filtration surgery (GFS).

METHODS

Biodegradable microfilms composed of poly (D-, L-lactide-co-caprolactone) (PLC) were fabricated and then pre-loaded PA-20% total weight. Fourteen New Zealand White rabbits were randomly divided into 3 treatment groups: GFS alone (n=4), GFS with PLC microfilms (n=4) and GFS with PA-loaded microfilm (n=6). Microfilms were inserted subconjunctivally, adjacent to the filtering surgical site. We monitored all eyes with slit-lamp examination, bleb photography and anterior segment optical coherence tomography (AS-OCT). Histology with immunohistochemistry was performed to determine the presence of any inflammation.

RESULTS

Prednisolone acetate 20%-loaded microfilms exhibited steady, sustained release in vitro. Eyes implanted with PA-loaded microfilms showed a significantly better bleb survival (100% vs. 37.5%, p<0.001) and reduced bleb vascularity (58%; 95% CI 54-62% vs. 30%; 95% CI 23-37%, p=0.001) compared to the control at 30 days postoperatively. Histology and immunohistochemistry demonstrated less T-cell infiltration in the eye implanted with PA-loaded microfilms.

CONCLUSION

Subconjunctival insertion of a PA-loaded biodegradeable microfilm exhibit sustained release of PA to reduce postoperative inflammation and prolong bleb survival in rabbit GFS.

Donor and surgical risk factors for primary graft failure following Descemet's stripping automated endothelial keratoplasty in Asian eyes

Background

Descemet’s stripping automated endothelial keratoplasty (DSAEK) has been shown to have superior refractive and visual results compared with penetrating keratoplasty, but higher rates of primary graft failure (PGF). This paper presents donor and surgical risk factors for PGF in DSAEK cases in Asian eyes.

Design

Retrospective case-control study.

Participants

All consecutive patients who underwent DSAEK at a tertiary referral teaching hospital from March 2006–December 2008.

Methods

Donor details analyzed were: age of donor, cause of donor death, death to harvesting time, donor storage time, distribution distance of tissue, preoperative endothelial cell count. Surgical factors analyzed were: donor diameter, donor thickness, and method of donor insertion. These risk factors in cases of PGF were compared with patients with successful DSAEK as the control group.

Main outcome measure

PGF.

Results

A total of 124 DSAEK procedures were performed. Six DSAEK procedures (five eyes of five patients; one eye with two failures) resulted in PGF (4.8%). Significant risk factors were found for PGF to include graft insertion using a folding technique (odds ratio [OR], 34.03; 95% confidence interval [CI], 3.75–314.32; P = 0.0017) and a small donor diameter (OR, 39.94; 95% CI, 2.18–732.17; P = 0.013).

Conclusion

The results of this study suggest that in Asian eyes with shallow anterior chambers, surgical trauma relating to the technique of donor insertion, and the use of a small donor are major risk factors for PGF following DSAEK.

Sustained release of an anti-glaucoma drug: demonstration of efficacy of a liposomal formulation in the rabbit eye

Topical medication remains the first line treatment of glaucoma; however, sustained ocular drug delivery via topical administration is difficult to achieve. Most drugs have poor penetration due to the multiple physiological barriers of the eye and are rapidly cleared if applied topically. Currently, daily topical administration for lowering the intra-ocular pressure (IOP), has many limitations, such as poor patient compliance and ocular allergy from repeated drug administration. Poor compliance leads to suboptimal control of IOP and disease progression with eventual blindness. The delivery of drugs in a sustained manner could provide the patient with a more attractive alternative by providing optimal therapeutic dosing, with minimal local toxicity and inconvenience. To investigate this, we incorporated latanoprost into LUVs (large unilamellar vesicles) derived from the liposome of DPPC (di-palmitoyl-phosphatidyl-choline) by the film hydration technique. Relatively high amounts of drug could be incorporated into this vesicle, and the drug resides predominantly in the bilayer. Vesicle stability monitored by size measurement and DSC (differential scanning calorimetry) analysis showed that formulations with a drug/lipid mole ratio of about 10% have good physical stability during storage and release. This formulation demonstrated sustained release of latanoprost in vitro, and then tested for efficacy in 23 rabbits. Subconjunctival injection and topical eye drop administration of the latanoprost/liposomal formulation were compared with conventional daily administration of latanoprost eye drops. The IOP lowering effect with a single subconjunctival injection was shown to be sustained for up to 50 days, and the extent of IOP lowering was comparable to daily eye drop administration. Toxicity and localized inflammation were not observed in any treatment groups. We believe that this is the first demonstration, in vivo, of sustained delivery to the anterior segment of the eye that is safe and efficacious for 50 days.