A simple and non-contact optical imaging probe for evaluation of corneal diseases

Non-contact imaging techniques are preferred in ophthalmology. Corneal disease is one of the leading causes of blindness worldwide, and a possible way of detection is by analyzing the shape and optical quality of the cornea. Here, a simple and cost-effective, non-contact optical probe system is proposed and illustrated. The probe possesses high spatial resolutions and is non-dependent on coupling medium, which are significant for a clinician and patient friendly investigation. These parameters are crucial, when considering an imaging system for the objective diagnosis and management of corneal diseases. The imaging of the cornea is performed on ex vivo porcine samples and subsequently on small laboratory animals, in vivo. The clinical significance of the proposed study is validated by performing imaging of the New Zealand white rabbit's cornea infected with Pseudomonas.

Note: A gel based imaging technique of the iridocorneal angle for evaluation of angle-closure glaucoma

Noninvasive medical imaging techniques have high potential in the field of ocular imaging research. Angle closure glaucoma is a major disease causing blindness and a possible way of detection is the examination of the anterior chamber angle in eyes. Here, a simple optical method for the evaluation of angle-closure glaucoma is proposed and illustrated. The light propagation from the region associated with the iridocorneal angle to the exterior of eye is considered analytically. The design of the gel assisted probe prototype is carried out and the imaging of iridocorneal angle is performed on an eye model.

An interchromosomal reciprocal translocation in wheat involving leaf rust resistance gene Lr34

'Thatcher' backcross lines RL6058 and RL6077 have adult-plant leaf rust resistance and were believed to have Lr34. However, genetic analysis revealed that the genes in the two lines were independent of each other. Previous work demonstrated that Lr34 is located on chromosome 7D. The leaf rust resistance gene in RL6058 must be on chromosome 7DS because no recombinants were observed between it and gene Lr29, known to be on chromosome 7DS. It was also linked with Rc3 (30.25 +/- 2.88%), a gene for purple coleoptile on chromosome 7DS. It was independent of Lr19 and NS1 (nonsuppressor mutant), which are located on 7DL. The leaf rust resistance gene in RL6077 was independent of genes Lr19 and Lr29. The presence of quadrivalents in pollen mother cells of the RL6058/RL6077 hybrid indicates that the Lr34 gene in RL6077 may have been translocated onto another chromosome. Lr34 from RL6058 and RL6077 may have been combined in four F3 lines derived from their intercross.

Automatic glaucoma diagnosis from fundus image

Glaucoma is currently diagnosed by glaucoma specialists using specialized imaging devices like HRT and OCT. Fundus imaging is a modality widely used in primary healthcare. An automatic glaucoma diagnosis system based on fundus image can be deployed to primary healthcare clinics and has potential for early disease diagnosis. A mass glaucoma screening program can also be facilitated using such a system. We present an automatic fundus image based cup-to-disc ratio measurement system; and demonstrate its potential for automatic objective glaucoma diagnosis and screening. It provides strong support to use fundus image as the modality for automatic glaucoma diagnosis.

Review of key findings from the Singapore Malay Eye Study (SiMES-1)

INTRODUCTION

This study highlights the key epidemiological findings from the Singapore Malay Eye Study (SiMES-1).

METHODS

SiMES-1 was a cross-sectional, population-based epidemiological study on eye diseases. It was performed on 3,280 randomly selected Malay adults living in the south-western part of Singapore. All study participants underwent various validated questionnaires and detailed eye examinations. A review of all papers published from SiMES-1 was performed.

RESULTS

A total of 24.6% of the study population had myopia, while 35.3% had hyperopia and 39.4% had astigmatism. 20.4% of the population had under-corrected refractive error. 1,338 (45.7%) participants were diagnosed to have cataracts in at least one eye. 8.6% of the study population had undergone cataract surgery in either eye, while 4.7% had bilateral cataract surgery. 150 (4.6%) participants were diagnosed to have glaucoma, of which primary open angle glaucoma was the most common type (3.2% of the study population), followed by secondary glaucoma (0.8%) and primary angle closure glaucoma (0.2%). Pterygium was diagnosed in 508 out of 3,266 study participants, giving a prevalence rate of 15.6%. The presence of diabetic retinopathy was observed in 421 (12.9%) out of 3,265 study participants. 183 (5.6%) study participants had some degree of age-related macular degeneration (AMD), of which 23 (0.7%) were classified as having late AMD.

CONCLUSION

This paper provides a summary of the prevalence of common eye diseases among the Singaporean adult Malay population and provides data useful for public health education and disease prevention.

Increased iris thickness and association with primary angle closure glaucoma

AIMS

To investigate the relationship between quantitative iris parameters and angle closure disease. methods: Participants with angle closure were recruited prospectively from glaucoma clinics. Anterior segment optical coherence tomography (AS-OCT) was performed under standardised dark conditions. Customised software was used on horizontal AS-OCT scans to measure iris thickness at 750 um (IT750) and 2000 um (IT2000) from the sclera spur, maximal iris thickness (ITM) and cross-sectional area of the iris (I-Area).

RESULTS

167 Angle closure (consisting of 50 primary angle-closure (PAC), 73 primary angle closure glaucoma (PACG) and 44 fellow eyes of acute PAC) and 1153 normal participants were examined. After adjusting for age, sex, pupil size and anterior chamber depth, mean IT750 (0.499 vs 0.451 mm, p<0.001), IT2000 (0.543 vs 0.479 mm, p<0.001), ITM (0.660 vs 0.602 mm, p<0.001) and I-Area (1.645 vs 1.570 mm(2), p=0.014) were significantly greater in angle closure (combined groups) versus normal eyes. Multivariate adjusted odd ratios (OR) of each parameter for the angle closure as compared with normal eyes were: IT750 OR1.7 (95% CI 1.1 to 2.7, p=0.032); IT2000 OR2.2 (95% CI 1.3 to 3.8, p=0.006) and ITM OR2.2 (95% CI 1.3 to 3.6, p=0.003), respectively, per 0.1 unit increase.

CONCLUSIONS

Increased iris thickness is associated with angle closure.

Comparison of Visante and slit-lamp anterior segment optical coherence tomography in imaging the anterior chamber angle

AIMS

To compare the diagnostic performance of two anterior segment optical coherence tomography (AS-OCT) devices in assessing the anterior chamber angle (ACA).

METHODS

Visante-OCT and slit-lamp-OCT (SL-OCT) were performed on 101 patients by a single operator. The AS-OCT images were processed by customised 'dewarping' software and assessed by two glaucoma specialists masked to clinical findings. A closed ACA was defined by the presence of contact between the iris and angle anterior to the scleral spur. Measurements of the ACA, anterior chamber depth (ACD), and pupil diameter were analysed. Gonioscopy was performed by another examiner masked to AS-OCT findings.

RESULTS

Qualitative analysis could be carried out in 83 (83%) eyes and quantitative analysis in 61 (60%) eyes. A closed angle in at least one quadrant of the eye was observed in 30 eyes with gonioscopy; Visante-OCT imaging identified 29 of 30 (97%) and SL-OCT imaging identified 27 of 30 (90%) of these eyes (P=0.50, McNemar test). Visante-OCT detected more eyes with at least one closed quadrant than SL-OCT (55 vs46 eyes, respectively, P=0.01). Overall, SL-OCT had better agreement with gonioscopy than with Visante-OCT. Both AS-OCTs showed good agreement for ACD measurements; however, SL-OCT tended to provide consistently higher ACA measurements and smaller pupil diameters than did Visante-OCT.

CONCLUSIONS

Both AS-OCT devices detected most of the eyes with closed ACA on gonioscopy. However, Visante-OCT detected more closed ACAs than did SL-OCT. The better agreement between SL-OCT and gonioscopy is likely because of the use of visible light during both examinations. The ACA measurements obtained with each device are not interchangeable.

Circulating tumor cells (CTC), [18F]fluorodeoxyglucose positron emission tomography, and computed tomography (PET/CT) for treatment monitoring in patients with metastatic breast cancer (MBC)

e12007

Background: Use of [18F]-fluorodeoxyglucose PET /CT and/or CTC is being investigated to follow up response to treatment in patients with MBC. It is not clear if these tests can be a surrogate for one another. Methods: We retrospectively analyzed a database of female patients with MBC undergoing chemotherapy or hormonal therapy. Most of these patients received at least 2 lines of therapy. Standard CT scan tumor measurements were used to assess response to therapy. CTC were defined either low (0–5) or high (>5). Maximum standard uptake values (max SUV) on PET scan were defined either low (<3) or high (>3). Correlation between the max SUV and CTC counts was statistically analyzed. Sensitivity, specificity, positive and negative predictive values were calculated from 2 x 2 table. Results: A total of 9 female patients with MBC were identified (mean age of 52 years). The receptor status of these patients includes 67 % positive for ER and 33 % positive for HER-2/neu. Median follow up was 9.8 months. There were 59 time points (> or = 4 weeks apart) when either PET/CT or CTC were performed. The results of PET/CT scans were compared with CTC at 38 events. The sensitivity of CTC to detect metastatic disease shown on PET/CT was 32% and specificity of 100%. The positive and negative predictive values were 100% and 32% respectively. There was a positive correlation between the max SUV and CTC count (p = 0.001). However in three patients, despite of progression of disease per PET/CT, CTC were undetectable at three different time points. Interestingly, two out of these three patients were triple negative. Disease progression was confirmed by biopsy in two of these patients. Conclusions: Our data suggest positive correlation between PET/CT scan and CTC. However, CTC had poor sensitivity and negative predictive value to detect progressive metastatic disease. Normal CTC values have to be interpreted cautiously in patients with MBC. We are now planning to investigate the utility of these tests, prospectively, in a large cohort of MBC patients.

No significant financial relationships to disclose.

Surgical management and genetic analysis of a Chinese family with the S171P mutation in the UBIAD1 gene, the gene for Schnyder corneal dystrophy

BACKGROUND

To describe the underlying molecular genetic basis, surgical management and phenotypic variation of Schnyder corneal dystrophy (SCD) identified in a four-generation Chinese family.

METHODS

This is an interventional case series of 13 members from a non-consanguineous Chinese family. All patients underwent complete ophthalmological examination and slit-lamp photography. Subsequent corneal transplantations were performed (n = 3). Blood samples were taken for DNA extraction and subsequent genetic analysis.

RESULTS

Genotyping indicated linkage to the locus at chromosome 1p36. Screening of the UBIAD1 gene identified a highly conserved mutation, Ser171Pro. Phenotypic variation in this large pedigree is similar to that seen in Caucasian patients. Surgical management of patients with anterior lamellar keratoplasty and deep anterior lamellar keratoplasty showed good visual outcomes.

CONCLUSIONS

The S171P mutation is described for the first time in a Chinese family. This is the largest non-Caucasian pedigree described with SCD. Visual rehabilitation may be performed successfully with lamellar surgical procedures as opposed to full-thickness corneal grafts.

Is measurement of adult height useful in screening for primary angle closure?

BACKGROUND

Adult height is independently related to ocular dimensions and shorter people have shorter globes and shallower anterior chambers. We investigated the relationship between adult height and angle dimensions to explore measuring height as a possible screening test for angle closure.

METHODS

A population-based, cross-sectional survey of adult Chinese living in the Tanjong Pagar district, Singapore was conducted. Anterior chamber depth, gonioscopic angle width and height were assessed using standardized protocols.

RESULTS

Data were available for 996 persons. Shorter people had shallower anterior chamber depth (2.35 mm for persons <144 cm vs 2.72 mm for persons >170 cm, P=0.008) and smaller gonioscopic angles (22 degrees for <144 cm vs 30 degrees for >170 cm, P=0.079). After controlling for age and gender, adult height was significantly related to anterior chamber depth (P=0.008) but not significantly related to gonioscopic angle width (P=0.079). Female sex and age > or = 50 years used together correctly identified 45/66 (68.2%) individuals with an occludable angle (sensitivity 68.2%, specificity 61.3%). Fewer people, 41/66 (62.1%), were correctly identified when height <160 cm was added to female sex and age 50 > or = years (sensitivity was 62.1% and specificity was 64.7%).

CONCLUSIONS

Shorter adult height is significantly associated with a shallower anterior chamber depth, but the addition of height contributed little to demographics (age and gender) as the preliminary screening criteria to identify individuals at risk of an occludable angle.

Prevalence of cataract surgery and post-surgical visual outcomes in an urban Asian population: the Singapore Malay Eye Study

AIM

The aim of the study was to describe the prevalence and visual outcomes of cataract surgery in an urban Asian population.

METHODS

This was a population-based study of 3280 Singapore Malays aged 40-80 years (response rate 78.7%). Participants had a standardised interview and comprehensive ocular examination. Poor post-operative visual outcome was defined as visual acuity </=20/60 in operated eyes of unilateral cataract extractions or in the better-seeing eye of bilateral cataract extractions. Factors associated with poor visual outcome were assessed.

RESULTS

Of 3280 participants, 284 (men 52.3%) had unilateral cataract extractions (age-standardised prevalence 4.7%, 95% CI 4.2% to 5.4%) and 154 persons (54%) had bilateral extractions. Older age, male sex and the presence of diabetes were significant factors associated with having had cataract surgery. Poor visual outcomes were present in 10.8% of the operated eyes using best-corrected visual acuity. Diabetic retinopathy (25.5%), glaucoma (17%), age-related macular degeneration (14.9%) and posterior capsular opacification (14.9%) were the main causes of poor visual outcome after surgery. Under-corrected refractive error accounted for 60% of patients with post-operative presenting visual acuity of </=20/60.

CONCLUSIONS

Five per cent of the sample of the Malay population aged 40-80 years in Singapore had cataract surgery. One in ten had post-operative best-corrected visual acuity of 20/60 or worse, largely related to concomitant retinal diseases.