Magnitude and causes of blindness in the developing world

Prevalence of systemic disease in patients undergoing cataract surgery at a hospital versus outpatient clinic

OBJECTIVE

To compare demographic and clinical characteristics of patients undergoing cataract surgery at a hospital versus a private outpatient clinic (POC) within a shared funding model in Ontario, Canada. Our tertiary academic hospital operates a unique funding arrangement, in which some hospital funds support cataract surgeries at a POC, enabling oversight of provincially funded surgeries at both sites.

DESIGN

Retrospective cohort study.

PARTICIPANTS

All patients who underwent cataract surgery in 2023 at both the hospital (Kingston Health Sciences Centre) and the affiliated POC were included.

METHODS

We compared demographic and clinical data, including age, gender, blood pressure, comorbidities (e.g., diabetes, hypertension), American Society of Anesthesiologists scores, and medication usage.

RESULTS

Patients included in this study numbered 3441 (1982 hospital patients and 1459 POC patients). Mean age was similar, although significantly more females underwent surgery at the POC (p = 0.004). Hospital patients had higher systolic blood pressure (p < 0.0001), higher rates of diabetes (1.5 odds ratio, 95% confidence interval [CI] 1.3-1.8; p < 0.0001), higher American Society of Anesthesiologist scores (0.3 mean difference, 95% CI 0.27-0.35; p < 0.0001), and higher smoking rates (p < 0.0001). The use of anticoagulation, antidiabetes, and prostate medications were significantly higher among hospital patients (p < 0.001), with greater use of antihypertensive medications (p = 0.018).

CONCLUSIONS

Our data support concerns that healthier patients are more likely to undergo surgery at outpatient clinics. Factors, such as mandated restrictions on patient selection at POCs, surgeon preference, and referral patterns may contribute. As outpatient surgical care grows, documenting these differences is essential to ensure fair distribution of resources and equitable access to care.

Autosomal recessive congenital cataract is associated with a novel 4-bp splicing deletion mutation in a novel C10orf71 human gene

Congenital cataract is one of the most genetically heterogeneous ocular conditions with different genes involved in its etiology. Here, we describe the analysis of a new candidate gene of a congenital bilateral cataract associated with polymalformative syndrome, moderate global developmental delay, microcephaly, axial hypotonia, intrauterine growth restriction and facial dysmorphism for two affected siblings. Molecular analysis included exome sequencing and genome wide homozygosity mapping revealed a region of homozygosity shared by the two affected siblings at 10q11.23. The new C10orf71 gene was included in this interval and direct sequencing of this gene revealed an already described homozygous c. 2123T > G mutation (p. L708R) for the two affected subjects. Interestingly, we revealed in contrast a 4-bp deletion on the 3'-splicing acceptor site of intron 3-exon 4, namely defined as IVS3-5delGCAA. The C10Orf71 gene expression analysis using RT-PCR showed an expression pattern in different fetal organs and tissues as well as in leukocytes and confirmed that the IVS3-5delGCAA deletion of the C10orf71 gene is a splicing mutation responsible for the shortening of the C10orf71 protein in the two related patients. The C10orf71 gene has not been described to date as associated to the autosomal recessive phenotype.

Correlation of Sunlight Exposure and Different Morphological Types of Age-Related Cataract

Purpose

The previous lab and clinical studies of the correlation between the ultraviolet B and age-related cataract (ARC) did not reach in the universal agreement, especially in different morphological types of ARC. It is important to systemically summarize those previous data of epidemiological studies, which might penetrate the relevance between three morphological types of ARC, cortical, nuclear, and posterior capsular (PSC), with sunlight exposure.

Methods

PubMed, Web of Science, CNKI, Embase, and Cochrane were searched online. Data were extracted and recalculated, and quality check was performed by hand. Review Manager was used to perform the fixed effects meta-analysis on ARC and its morphological types. The highest exposed dose group was defined as the exposed group, and the lowest dose group as the control group as possible.

Results

Finally, the number of analyzed studies was 31: 20 for ARC and twelve, eleven, and nine for the morphological types cortical, nuclear, and PSC, respectively. The pooled OR for ARC was 1.15 (range 1.00~43.78, 95% CI 1.09 to 1.21). The cortical cataract revealed a slightly higher risk, and pooled OR was 1.03 (range 0.67~2.91, 95% CI 1.02 to 1.03). But the pooled OR for nuclear and PSC were 1.00 (range 0.50~5.35, 95% CI 1.00 to 1.00) and 0.99 (range 0.57~1.87, 95% CI 0.95 to 1.01), respectively.

Conclusions

The systemic analysis of epidemiological articles reported till now reveals a significantly increased risk of ARC for those exposed with more sunlight, especially the morphological type of cortical cataract.

Examining the effects of cigarette smoke on mouse lens through a multi OMIC approach

Here, we report a multi OMIC (transcriptome, proteome, and metabolome) approach to investigate molecular changes in lens fiber cells (FC) of mice exposed to cigarette smoke (CS). Pregnant mice were placed in a whole-body smoke chamber and a few days later pups were born, which were exposed to CS for 5 hours/day, 5 days/week for a total of 3½ months. We examined the mice exposed to CS for CS-related cataractogenesis after completion of the CS exposure but no cataracts were observed. Lenses of CS-exposed and age-matched, untreated control mice were extracted and lens FC were subjected to multi OMIC profiling. We identified 348 genes, 130 proteins, and 14 metabolites exhibiting significant (p < 0.05) differential levels in lens FC of mice exposed to CS, corresponding to 3.6%, 4.3%, and 5.0% of the total genes, protein, and metabolites, respectively identified in this study. Our multi OMIC approach confirmed that only a small fraction of the transcriptome, the proteome, and the metabolome was perturbed in the lens FC of mice exposed to CS, which suggests that exposure of CS had a minimal effect on the mouse lens. It is worth noting that while our results confirm that CS exposure does not have a substantial impact on the molecular landscape of the mouse lens FC, we cannot rule out that CS exposure for longer durations and/or in combination with other morbidities or environmental factors would have a more robust effect and/or result in cataractogenesis.

Prevalence, Risk Factors, and Patient Awareness of Diabetic Retinopathy in Saudi Arabia: A Review of the Literature

Diabetes mellitus is a common disease in Saudi Arabia and globally, with some studies reporting about 30% prevalence among the Saudi population. Diabetic retinopathy (DR) is the leading cause of blindness among working-age patients, and it has a prevalence of 34.6% among diabetics worldwide. The objectives of this review were to examine the prevalence of DR in Saudi Arabia, describe the major associated risk factors, and raise awareness about the disease among diabetics.

The prevalence of DR in Saudi Arabia has risen substantially in recent decades. Significant risk factors associated with DR include older age, longer duration of diabetes, poor glycemic control, and hypertension. Awareness and education about diabetes are associated with better outcomes and fewer complications.

Point-of-care Ultrasound Detection of Cataract in a Patient with Vision Loss: A Case Report

Background: Point-of-care ocular ultrasound in the emergency department (ED) is an effective tool for promptly evaluating for several vision-threatening etiologies and can be used to identify more slowly progressing etiologies as well, such as cataract formation within the lens. Case Report: A 62-year-old female presented to the ED with a two-day history of painless vision loss of the left eye as well as reduced vision for the prior 30 days. Conclusion: Point-of-care ultrasound was performed and showed calcification of the lens consistent with cataract.

Autosomal recessive congenital cataracts linked to HSF4 in a consanguineous Pakistani family

PURPOSE

To investigate the genetic basis of autosomal recessive congenital cataracts (arCC) in a large consanguineous Pakistani family.

METHODS

All participating members of family, PKCC074 underwent an ophthalmic examination. Slit-lamp photographs were ascertained for affected individuals that have not been operated for the removal of the cataractous lens. A small aliquot of the blood sample was collected from all participating individuals and genomic DNAs were extracted. A genome-wide scan was performed with polymorphic short tandem repeat (STR) markers and the logarithm of odds (LOD) scores were calculated. All coding exons and exon-intron boundaries of HSF4 were sequenced and expression of Hsf4 in mouse ocular lens was investigated. The C-terminal FLAG-tagged wild-type and mutant HSF4b constructs were prepared to examine the nuclear localization pattern of the mutant protein.

RESULTS

The ophthalmological examinations suggested that nuclear cataracts are present in affected individuals. Genome-wide linkage analyses localized the critical interval to a 10.95 cM (14.17 Mb) interval on chromosome 16q with a maximum two-point LOD score of 4.51 at θ = 0. Sanger sequencing identified a novel missense mutation: c.433G>C (p.Ala145Pro) that segregated with the disease phenotype in the family and was not present in ethnically matched controls. Real-time PCR analysis identified the expression of HSF4 in mouse lens as early as embryonic day 15 with a steady level of expression thereafter. The immunofluorescence tracking confirmed that both wild-type and mutant HSF4 (p.Ala145Pro) proteins localized to the nucleus.

CONCLUSION

Here, we report a novel missense mutation in HSF4 associated with arCC in a familial case of Pakistani descent.

Pain Perception and Acceptance of Illness in Patients Undergoing Phacoemulsification Cataract Surgery under Drip Anesthesia

For many years, cataracts have been the main cause of vision loss and vision impairments in the world (43% and 33%, respectively). Currently, the most common surgical method for treating cataracts is phacoemulsification. The aim of this study was to assess the pain perception and acceptance of illness connected with awaiting phacoemulsification cataract surgery under intravenous drip anesthesia, as well as to determine the effect of selected sociodemographic factors on the above. Methods: The study was conducted in a group of patients of the Department of Ophthalmology, University Clinical Hospital in Białystok, Poland suffering from cataracts, who underwent phacoemulsification surgery under intravenous drip anesthesia. The study group consisted of 151 people. The study used an original short questionnaire and three standardized psychometric scales: The acceptance of illness scale (AIS), the Beliefs about Pain Control Questionnaire (BPCQ), and the Coping Strategies Questionnaire (CSQ). Results: The median overall AIS point value was 24 points, which is considered an average score in terms of disease acceptance. Respondents assessed the influence of individual factors on the level of perceived pain and the impact of individual strategies for coping with pain similarly. The level of perceived pain decreased with the patient’s age. People with a higher education level experienced a greater level of pain; however, this relationship was not statistically significant. The place of residence did not affect the level of pain experienced during the procedure. Women had a greater level of acceptance of illness. The respondents’ education level negligibly differentiated the approach to the disease. The place of residence also did not affect the assessment of illness acceptance as measured by the AIS. Whether the surgery pertained to the first or second eye did not significantly affect the approach to the disease. Conclusions: The level of acceptance of illness and pain perception were at a moderate level among the patients. The acceptance of illness was significantly influenced by the age of patients and the waiting period for phacoemulsification, and this level of acceptance decreased significantly with the increasing age of patients. The longer the waiting period for surgery, the lower the acceptance of illness. Sex significantly differentiated the level of pain experienced during the procedure. Education and place of residence did not significantly affect the acceptance of illness and the feeling of pain.

All‑trans‑retinoic acid modulates TGF‑β‑induced apoptosis, proliferation, migration and extracellular matrix synthesis of conjunctival fibroblasts by inhibiting PI3K/AKT signaling

Conjunctival fiber generation is implicated in a wide spectrum of ocular diseases. Conjunctival wound healing is characterized by inflammation followed by re‑epithelialization, synthesis of new extracellular matrix (ECM), wound contraction and subconjunctival scar formation. The primary cause for the failure of glaucoma filtration surgery results from the excessive scarring of the filtering bleb. All‑trans‑retinoic acid (ATRA), a derivative of vitamin A, is a potent regulator of ECM synthesis, growth and differentiation. Following a previous study, which revealed that ATRA could inhibit transforming growth factor‑β‑induced human conjunctival fibroblast (HConF)‑mediated collagen gel contraction, the present study aimed to investigate the effects of ATRA on HConF migration, apoptosis, proliferation and ECM synthesis. To achieve this, the present study used Transwell migration, wound healing and Cell Counting Kit‑8 assays, flow cytometry and western blot analysis. In addition, the present study aimed to elucidate the mechanism of ATRA in mediating resistance to conjunctival scar formation. ATRA treatment resulted in an increased level of HConF apoptosis, reduced proliferation and migration, decreased collagen I and fibronectin expression, and decreased phosphorylation of PI3K and AKT. Thus, the present study showed a role for ATRA in inhibiting HConF migration, proliferation and ECM synthesis, and in promoting HConF apoptosis through the inhibition of the PI3K/AKT signaling pathway.

Barriers for Cataract Treatment among Elderly in Sri Lanka

Cataract is still the leading cause of blindness. Many government institutes and voluntary organizations in Sri Lanka are providing free treatment services to patients with cataract. Still people are not patronizing the available free services; thus they have to live with impaired vision or blindness. This paper describes the barriers for cataract treatment among the population over 60 years of age. Out of 470 elders, 379 were found to have some kind of cataract. This study demonstrated lack of awareness and knowledge, socioeconomic factors, and misconceptions as the main barriers for cataract treatment which has led to a lower cataract surgery rate irrespective of the high cataract prevalence reported. Findings of this study highlight the importance of cataract as a common health problem in elderly and need for removal of the barriers for its treatment which should be given due prominence in the formulation of public health policy in Sri Lanka at the earliest.

[Bioinorganic chemical composition of the lens and methods of its investigation]

Bioinorganic chemical composition of the lens of human and experimental animals (cows, dogs, rats, rabbits) have been analyzed in various studies. In most cases, the studies employed different methods to determine the gross (total) composition of chemical elements and their concentrations in the examined samples. Less frequently, they included an assessment of the distribution of chemical elements in the lens and correlation of their concentration with its morphological changes. Chemical elements from all groups (series) of the periodic classification system were discovered in the lens substance. Despite similar investigation methods, different authors obtained contradicting results on the chemical composition of the lens. This article presents data suggesting possible correlation between inorganic chemical elements in the lens substance with the development and formation of lenticular opacities. All currently employed methods are known to only analyze limited number of select chemical elements in the tissues and do not consider the whole range of elements that can be analyzed with existing technology; furthermore, the majority of studies are conducted on the animal model lens. Therefore, it is feasible to continue the development of the chemical microanalysis method by increasing the sensitivity of Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) with the purpose of assessing the gross chemical composition and distribution of the elements in the lens substance, as well as revealing possible correlation between element concentration and morphological changes in the lens.

The Prevalence of Blindness and Low Vision in Older Onset Diabetes Mellitus and Associated Factors: A Community-Based Study

PURPOSE

This community-based study was conducted to assess the prevalence and related factors of low vision and legal blindness in older onset diabetic patients (diagnosed at age 30 and older).

METHODS

All known diabetic patients who live in the four primary health care center region Abidinpaşa Ankara, Turkey (total population: 96,348) were included in this cross-sectional study. The prevalence of known diabetes mellitus is 2.2%, of which 96.6% are older onset and 3.4% are younger onset.

RESULTS

In the older onset diabetes group (1289 cases), 10.8% of the population had low vision and only 2.7% had legal blindness. Diabetic retinopathy (DR) was observed in 23.6% of the patients with low vision (42% proliferative DR) and in 62.9% of the patients with legal blindness (90.1 % proliferative DR).

CONCLUSIONS

In older onset diabetic patients with low vision, nonproliferative retinopathy was a more frequent cause of impaired vision than proliferative retinopathy. Low vision and legal blindness caused by retinopathy were significantly associated with sex, age at examination, age at diagnosis, duration of diabetes, type of diabetes treatment, and hypertension in univariate analysis. However, in logistic regression analysis, low vision and legal blindness caused by retinopathy were found to be associated with longer duration of diabetes (> or =15 years), use of insulin, and hypertension.

Fine mapping of chromosome 9 locus associated with congenital cataract

PURPOSE

The purpose of this study was to study the molecular basis of inherited autosomal recessive cataracts in Pakistan population and to identify the molecular defect segregating with the disease phenotype.

METHODS

Families having two or more affected individuals were identified through hospital, blood samples were collected and DNA was extracted. We employed the traditional strategy of linkage analysis using M13-labeled primers to map the already known genes for autosomal recessive cataract. Statistically, the data were evaluated through LOD score.

RESULTS

Ten families affected with autosomal receive congenital cataract were enrolled for this study. Overall, three families were linked to reported loci for autosomal recessive congenital cataract. Out of these, one family Bl05 was linked to a cataract locus at 9q13. Fine mapping of the chromosome 9 locus considerably delimited the previously reported linkage interval from 13.99 to 7.99 cM in this study.

CONCLUSION

Our results reduced the linkage interval of previously reported cataract locus on chromosome 9, thus considerably reducing the number of candidate genes.

Identifying glaucoma patients by applying multivariate analyses of cardiovascular signals

Glaucoma is a disease that damages the eye's optic nerve. However, the exact cause of this optic nerve damage is not yet fully understood. Besides the factors of age, genetics and others, such as obesity, medication and migraines, a vascular dysfunction is believed to be a significant factor leading to glaucoma. This study's objective was to investigate whether these vascular dysfunctions could be recognized by analyzing cardiovascular regulation in glaucoma patients. Linear and nonlinear methods were applied to the extracted heart rate (HR), and systolic/ diastolic blood pressure (DBP) time series to discriminate between 35 healthy controls and 20 glaucoma patients. The combination of indices from 30-min analysis of time domain (Renyi entropy of systolic blood pressure) and nonlinear dynamics (segmented Poincare plot analysis of DBP, high-resolution joint symbolic dynamics of DBP/ HR) were able to differentiate between controls and patients with a specificity and sensitivity of > 95%. Since changes in short-term blood pressure regulation patterns and heart-rate coupling are clear signs of a vascular dysfunction, this approach could be useful for providing an earlier diagnosis of glaucoma in clinical practice.

Safety and efficacy of phacoemulsification and intraocular lens implantation through a small pupil using minimal iris manipulation

Purpose

The aim of this study was to compare the results of phacoemulsification through a small pupil using minimal iris manipulation versus phacoemulsification through a well-dilated pupil.

Methods

This prospective randomized control (comparative) study comprised 78 patients (group I) with a maximally dilated pupil size of ≤4.00 mm and 45 patients (group II) with dilated pupil size of ≥7.00 mm. In group I patients, only viscodilation and minimal push-and-pull iris stretching with two collar-button iris-retractor hooks were utilized without iris manipulation. Phacoemulsification was performed by two senior surgeons and the technique used consisted of either stop and chop or quick chop, infusion/aspiration of lens cortex, capsular bag refill with ocular viscoelastic devices, and implantation of an acrylic foldable intraocular lens. Patients were examined on the first day and 1 month postoperatively.

Results

Forty-six eyes of group I patients had pseudoexfoliation syndrome, eleven eyes had previous glaucoma surgery, 14 eyes had angle-closure or open-angle glaucoma, and seven eyes had posterior synechiae with iritis. In group I patients, the mean pupil size measured under an operating microscope was 3.2 mm preoperatively, 4.3 mm after viscoelastic and mechanical pupil dilation, and 4.1 mm at the end of a surgical procedure. Rupture of the zonular fibers occurred in six patients of group I and the intraocular lens was implanted in the sulcus. Small iris-sphincter rupture and small hemorrhages occurred in four eyes during pupillary manipulation, but they were not evident at the end of the surgery. In group II patients, no intraoperative complications occurred. Signs of significant corneal edema and iritis were observed more frequently in group I eyes (26 eyes and 20 eyes, respectively) on the first postoperative day in comparison with group II eyes (ten eyes and six eyes, respectively). Intraocular pressure was <20 mmHg in all eyes of both groups. One month postoperatively, the pupil was round and reactive to light, the anterior chamber was quiet, and the cornea was clear in all eyes. The best-corrected visual acuity on Snellen chart was 20/40 (Monoyer’s scale) or better in both groups.

Conclusion

Phacoemulsification through a small pupil using minimal iris manipulation can be safe and exhibits the same results as those obtained with phacoemulsification through normal pupils.

Profile of paediatric low vision population: a retrospective study from Nepal

BACKGROUND

Childhood blindness and low vision have become major public health problems in developing countries. The purpose of this study was to categorise the causes of visual impairment according to aetiology and provide detailed local information on visually impaired children seeking low-vision services in a tertiary eye centre in Nepal.

METHODS

A retrospective study was conducted of all visually impaired children (visual acuity of less than 6/18 in the better eye), aged less than 17 years seen in the low-vision clinic at the Sagarmatha Chaudhary Eye Hospital in Lahan between January 1, 2012 and December 31, 2013.

RESULTS

Of the 558 visually impaired children, the majority were males, 356 (63.7 per cent). More than half (56.5 per cent) of the children were in the 11 to 16 years age group. Many of the low-vision children (52.9 per cent) were identified as having moderate visual impairment (visual acuity less than 6/18 to 6/60). Most children were diagnosed with childhood (36.2 per cent) or genetic (35.5 per cent) aetiology, followed by prenatal (22.2 per cent) and perinatal (6.1 per cent) aetiologies. Refractive error and amblyopia (20.1 per cent), retinitis pigmentosa (14.9 per cent) and macular dystrophy (13.4 per cent) were the most common causes of paediatric visual impairment. Nystagmus (50.0 per cent) was the most common cause of low vision in the one to five years age group, whereas refractive error and amblyopia were the major causes in the six to 10 and 11 to 16 years age group (17.6 and 22.9 per cent, respectively). Many of the children (86.0 per cent) were prescribed low-vision aids and 72.0 per cent of the low-vision aid users showed an improvement in visual acuity either at distance or near.

CONCLUSION

Paediatric low vision has a negative impact on the quality of life in children. Data from this study indicate that knowledge about the local characteristics and aetiological categorisation of the causes of low vision are essential in tackling paediatric visual impairment. The findings also signify the importance of early intervention to ensure a better quality of life.

Missense Mutations in CRYAB Are Liable for Recessive Congenital Cataracts

PURPOSE

This study was initiated to identify causal mutations responsible for autosomal recessive congenital cataracts in consanguineous familial cases.

METHODS

Affected individuals underwent a detailed ophthalmological and clinical examination, and slit-lamp photographs were ascertained for affected individuals who have not yet been operated for the removal of the cataractous lens. Blood samples were obtained, and genomic DNA was extracted from white blood cells. A genome-wide scan was completed with short tandem repeat (STR) markers, and the logarithm of odds (LOD) scores were calculated. Protein coding exons of CRYAB were sequenced, bi-directionally. Evolutionary conservation was investigated by aligning CRYAB orthologues, and the expression of Cryab in embryonic and postnatal mice lens was investigated with TaqMan probe.

RESULTS

The clinical and ophthalmological examinations suggested that all affected individuals had nuclear cataracts. Genome-wide linkage analysis suggested a potential region on chromosome 11q23 harboring CRYAB. DNA sequencing identified a missense variation: c.34C>T (p.R12C) in CRYAB that segregated with the disease phenotype in the family. Subsequent interrogation of our entire cohort of familial cases identified a second familial case localized to chromosome 11q23 harboring a c.31C>T (p.R11C) mutation. In silico analyses suggested that the mutations identified in familial cases, p.R11C and p.R12C will not be tolerated by the three-dimensional structure of CRYAB. Real-time PCR analysis identified the expression of Cryab in mouse lens as early as embryonic day 15 (E15) that increased significantly until postnatal day 6 (P6) with steady level of expression thereafter.

CONCLUSION

Here, we report two novel missense mutations, p.R11C and p.R12C, in CRYAB associated with autosomal recessive congenital nuclear cataracts.

Homozygosity mapping identifies a GALK1 mutation as the cause of autosomal recessive congenital cataracts in 4 adult siblings

OBJECTIVE

Monogenic congenital cataract is one of the most genetically heterogeneous ocular conditions with almost 30 different genes involved in its etiology. In adult patients, genotype-phenotype correlations are troubled by eye surgery during infancy and/or long-term ocular complications. Here, we describe the molecular diagnosis of GALK1 deficiency as the cause of autosomal recessive congenital cataract in a family from Costa Rica.

METHODS

Four affected siblings were included in the study. All of them underwent eye surgery during the first decade but medical records were not available. Congenital cataract was diagnosed by report. Molecular analysis included genome wide homozygosity mapping using a 250K SNP Affymetrix microarray followed by PCR amplification and direct nucleotide sequencing of candidate gene.

RESULTS

Genome wide homozygosity mapping revealed a 6Mb region of homozygosity shared by two affected siblings at 17q25. The GALK1 gene was included in this interval and direct sequencing of this gene revealed a homozygous c.1144C>T mutation (p.Q382) in all four affected subjects.

CONCLUSIONS

This work demonstrates the utility of homozygosity mapping in the retrospective diagnosis of a family with congenital cataracts in which ocular surgery at early age, the lack of medical records, and the presence of long term eye complications, impeded a clear clinical diagnosis during the initial phases of evaluation.

An overview of a UK paediatric visual impaired population and low vision aid provision

A retrospective study was carried out to evaluate the paediatric visual impaired population attending the Low Vision Clinic at Sheffield Teaching Hospitals NHS Foundation Trust, over a period of 14 years. Data were collected and analysed for children less than 17 years for prevalence, demographics, registration status, aetiologies, and types of low vision aids issued. The total number of children identified was 204. Of these, 19 percent of the children were registered blind, 45 percent were registered partially sighted, and 36 percent were not registered. The four diagnostic groups were genetic (29%), prenatal (36%), perinatal (23%), and childhood (12%). Describing local characteristics of paediatric visual impairment is a useful measure of current low vision service provision. This information can further inform educational, social, and health needs for the visually impaired children to ensure adequate service provision.

Autosomal recessive congenital cataract linked to EPHA2 in a consanguineous Pakistani family

PURPOSE

To investigate the genetic basis of autosomal recessive congenital cataracts in a consanguineous Pakistani family.

METHODS

All affected individuals underwent a detailed ophthalmological and clinical examination. Blood samples were collected and genomic DNAs were extracted. A genome-wide scan was performed with polymorphic microsatellite markers. Logarithm of odds (LOD) scores were calculated, and Eph-receptor type-A2 (EPHA2), residing in the critical interval, was sequenced bidirectionally.

RESULTS

The clinical and ophthalmological examinations suggested that all affected individuals have nuclear cataracts. Genome-wide linkage analyses localized the critical interval to a 20.78 cM (15.08 Mb) interval on chromosome 1p, with a maximum two-point LOD score of 5.21 at theta=0. Sequencing of EPHA2 residing in the critical interval identified a missense mutation: c.2353G>A, which results in an alanine to threonine substitution (p.A785T).

CONCLUSIONS

Here, we report for the first time a missense mutation in EPHA2 associated with autosomal recessive congenital cataracts.

Brinzolamide/timolol: in open-angle glaucoma and ocular hypertension

Brinzolamide 1%/timolol 0.5% fixed combination (brinzolamide/timolol) is a twice-daily eyedrops suspension comprising the carbonic anhydrase-II inhibitor brinzolamide and the beta-adrenergic receptor antagonist timolol. Brinzolamide/timolol produced clinically relevant reductions in mean intraocular pressure (IOP) from baseline and was more effective than brinzolamide or timolol monotherapy in lowering IOP in a 6-month, randomized, phase III trial in patients with open-angle glaucoma or ocular hypertension (n = 523). The proportion of patients achieving a mean IOP of <18 mmHg was significantly greater in recipients of brinzolamide/timolol than in recipients of brinzolamide or timolol monotherapy. The IOP-lowering efficacy of brinzolamide/timolol was maintained for up to 12 months, and was no less effective than dorzolamide 2%/timolol 0.5% solution (dorzolamide/timolol) in a randomized, phase III, noninferiority trial (n = 437). Brinzolamide/timolol was generally well tolerated and was associated with significantly lower ocular discomfort scores than dorzolamide/timolol. Moreover, a significantly greater number of patients expressed a preference for brinzolamide/timolol over dorzolamide/timolol. The main ocular adverse event was blurred vision, and was not considered to be a safety issue.

Cost-effectiveness of reducing wait times for cataract surgery in Ontario

BACKGROUND

Reducing wait times for cataract surgery is a priority in Ontario. However, no previous analysis has determined whether the extra treatment volumes required to reduce wait times are of good monetary value when compared with allocating those same financial resources to new programs, drugs, or technologies. The objective of the study was to use queuing models to determine the cost-effectiveness of reducing, to target levels, wait times for cataract surgery at the provincial level within 1 to 10 years by increasing treatment volumes.

METHODS

A cost-effectiveness analysis was performed by estimating the extra treatment volume required to reduce wait times using queuing model methodology. The cost of these extra treatments was obtained from Ontario provincial data. The incremental benefits of surgery are improvements in quality-adjusted life years (QALYs), and these values were obtained from the clinical literature. Incremental costs were compared with incremental benefits to determine an incremental cost-effectiveness ratio.

RESULTS

To reach the publicly stated target wait times, annual treatment volumes must increase by 4%. An extra increase in treatment volumes of 25,660 must also be provided for the transition period from the current wait time. The incremental cost-effectiveness ratio is $17,829 per QALY if the target wait time is achieved in 5 years, and this ratio is less than the common threshold for approval of new interventions, of $50,000 per QALY.

INTERPRETATION

Increasing treatment volumes is a cost-effective way of reducing wait times.

Evaluation of Goldmann Applanation Tonometry Using a Nonlinear Finite Element Ocular Model

Goldmann applanation tonometry (GAT) is the internationally accepted standard for intra-ocular pressure (IOP) measurement, which is important for the diagnosis of glaucoma. The technique does not consider the effect of the natural variation in the corneal thickness, curvature and material properties. As these parameters affect the structural resistance of the cornea, their variation is expected to lead to inaccuracies in IOP determination. Numerical Analysis based on the finite element method has been used to simulate the loading conditions experienced in GAT and hence assess the effect of variation in corneal parameters on GAT IOP measurements. The analysis is highly nonlinear and considers the hyper-elastic J-shaped stress-strain properties of corneal tissue observed in laboratory tests. The results reveal a clear association between both the corneal thickness and material properties, and the measured IOP. Corneal curvature has a considerably lower effect. Similar trends have been found from analysis of clinical data involving 532 patients referred to the Glaucoma Unit at Moorfields Hospital, and from earlier mathematical analyses. Nonlinear modelling is shown to trace the behaviour of the cornea under both IOP and tonometric pressure, and to be able to provide additional, and potentially useful, information on the distribution of stress, strain, contact pressure and gap closure.

Cataract surgery and diabetic retinopathy

Diabetes is a risk factor for the development of cataracts. Studies have shown an increased risk of ocular complications in diabetics after cataract surgery, but modern surgical techniques have minimized them, leading to an overall good visual outcome. Macular edema before surgery is the most common condition that limits post-operative visual recovery. Thus, pre-operative laser treatment is needed. Photocoagulation of preproliferative or early proliferative diabetic retinopathy is also advisable, due to the increased risk of iris neovascularization or retinopathy progression after surgery.

Incidence of visual loss in rural southwest Uganda

BACKGROUND

Surveys have been conducted to measure prevalence of eye disease in Africa, but not of incidence, which is needed to forecast trends. The incidence of visual loss is reported in southwest Uganda.

METHODS

A rural population residing in 15 neighbouring villages was followed between 1994-5 (R1) and 1997-8 (R2). Survey staff screened adult residents (13 years or older) for visual acuity using laminated Snellen's E optotype cards at each survey. Those who failed (VA >6/18) were evaluated by an ophthalmic clinical officer and an ophthalmologist. Incidence of visual loss (per 1000 person years (PY)) was calculated among those who had normal vision at R1.

RESULTS

2124 people were studied at both survey rounds (60.9% of those screened at R1); 48% were male. Participants in R1 were older (34.7 versus 31.5 years at R2, p<0.001). Visual loss in R2 occurred in 56 (2.8%) of 1997, yielding a crude incidence rate of 9.9, and an age standardised incidence rate of 13.2, per 1000 PY. Incidence of visual loss increased with age from 1.21 per 1000 PY among people aged 13-34 to 64.2 per 1000 PY in those aged 65 years or older (p for trend >0.001). The six commonest causes of visual loss were: cataract, refractive error, macular degeneration, chorioretinitis, glaucoma, and corneal opacity. If similar rates are assumed for the whole of Uganda, it is estimated that 30 348 people would develop bilateral blindness or bilateral visual impairment, per year.

CONCLUSIONS

Cataract and refractive error were the major causes of incident visual loss in south west Uganda. These data are valuable for forecasting and planning eye services.

Novel antisense oligonucleotides targeting TGF-beta inhibit in vivo scarring and improve surgical outcome

The scarring response is an important factor in many diseases throughout the body. In addition, it is a major problem in influencing results of surgery. In the eye, for example, post-operative scarring can determine the outcome of surgery. This is particularly the case in the blinding disease glaucoma, where several anti-scarring regimens are currently used to improve glaucoma surgery results, but are of limited use clinically because of severe complications. We have recently identified transforming growth factor-beta (TGF-beta) as a target for post-operative anti-scarring therapy in glaucoma, and now report the first study of novel second-generation antisense phosphorothioate oligonucleotides against TGF-beta in vivo. Single applications of a TGF-beta OGN at the time of surgery in two different animal models closely related to the surgical procedure performed in glaucoma patients, significantly reduced post-operative scarring (P<0.05) and improved surgical outcome. Our findings suggest that TGF-beta antisense oligonucleotides have potential as a new therapy for reducing post-surgical scarring. Its long-lasting effects after only a single administration at the time of surgery make it particularly attractive clinically. Furthermore, although we have shown this agent to be useful in the eye, it could have widespread applications anywhere in the body where the wound-healing response requires modulation.

Survey of glaucoma in an eye clinic in Ghana, West Africa

PURPOSE

To report the various types of glaucoma among West African patients presenting to an eye clinic in Ghana.

METHODS

A complete evaluation was performed in 198 consecutive Ghanaian glaucoma patients. Main outcome measures included intraocular pressure, visual acuity, gonioscopy findings, visual field, and total number of glaucoma medications.

RESULTS

The most common form of glaucoma was primary open-angle glaucoma (44.2%). Open-angle glaucoma suspects also comprised a large percentage of the group (30.5%). Chronic angle-closure glaucoma was diagnosed in 6.6% of the patients.

CONCLUSIONS

Primary open-angle glaucoma is the most common form of glaucoma being treated in this outpatient eye clinic in Ghana. Chronic angle-closure glaucoma was the second most common form of glaucoma in this series and was usually undiagnosed due to a lack of gonioscopic evaluation. Gonioscopy is an important diagnostic tool that should be promoted to guide more effective glaucoma treatment in this region. Pseudoexfoliation and pseudoexfoliation-associated glaucoma were not seen in this population.

Prevalence of blindness and low vision in Malaysian population: results from the National Eye Survey 1996

BACKGROUND

A national eye survey was conducted in 1996 to determine the prevalence of blindness and low vision and their major causes among the Malaysian population of all ages.

METHODS

A stratified two stage cluster sampling design was used to randomly select primary and secondary sampling units. Interviews, visual acuity tests, and eye examinations on all individuals in the sampled households were performed. Estimates were weighted by factors adjusting for selection probability, non-response, and sampling coverage.

RESULTS

The overall response rate was 69% (that is, living quarters response rate was 72.8% and household response rate was 95.1%). The age adjusted prevalence of bilateral blindness and low vision was 0.29% (95% CI 0.19 to 0.39%), and 2.44% (95% CI 2.18 to 2.69%) respectively. Females had a higher age adjusted prevalence of low vision compared to males. There was no significant difference in the prevalence of bilateral low vision and blindness among the four ethnic groups, and urban and rural residents. Cataract was the leading cause of blindness (39%) followed by retinal diseases (24%). Uncorrected refractive errors (48%) and cataract (36%) were the major causes of low vision.

CONCLUSION

Malaysia has blindness and visual impairment rates that are comparable with other countries in the South East Asia region. However, cataract and uncorrected refractive errors, though readily treatable, are still the leading causes of blindness, suggesting the need for an evaluation on accessibility and availability of eye care services and barriers to eye care utilisation in the country.

Visual impairment and blindness in Europe and their prevention

The European region currently differs in many aspects, such as political, socioeconomic, and geographical. After substantial political changes at the beginning of the 1990s, the majority of central and eastern European countries started to rebuild their healthcare systems. It is apparent that eastern Europe represents a highly diverse region where the difference among countries broadens year after year. In highly industrialised countries of Europe, the leading causes of childhood serious visual loss are lesions of the central nervous system, congenital anomalies and retinal disorders. In the middle income countries of Europe, congenital cataract, glaucoma and, mainly, retinopathy of prematurity are highly expressed. The major cause of serious visual loss in adults in industrialised countries is age related macular degeneration. The other conditions comprise cataract, glaucoma, diabetic retinopathy, and uncorrected/uncorrectable refractive errors, along with low vision. In people of working age, diabetic retinopathy, retinopathy pigmentosa, and optic atrophy are the most frequently reported causes of serious visual loss. In the middle income countries of Europe, advanced cataract, glaucoma, and diabetic retinopathy are more frequently observed.

Quality of life in patients with early, moderate and advanced glaucoma

PURPOSE

To evaluate the quality of life in glaucomatous patients using two different questionnaires: the medical outcomes study 36-item short-form health survey (MOS SF-36) and Viswanathan et al's questionnaire and to compare these two questionnaires.

METHODS

Seventy-seven patients with glaucoma were consecutively selected. Two force-choice questionnaires were administered to each patient. Viswanathan et al's questionnaire was related to visual disability and the second was related to the quality of life from the MOS 36-item short-form health survey. Both questionnaires were evaluated among all the considered patients and the results were compared. Then the questionnaire which did the best evaluation was used to test the quality of life in three different subgroups based on the mean deviation of the worse eye. Mann-Whitney non parametric test and Spearman's r coefficient were used and a P value less than 0.05 was considered to be statistically significant. A linear regression model was used.

RESULTS

In the entire group (n = 77) the Mean Deviation (MD) was -6.5 +/- 6.8 dB (mean +/- standard deviation) and Corrected Pattern Standard Deviation (CPSD) was 4.7 +/- 4.1 dB. The score of the Viswanathan et al's questionnaire was 8.3 +/- 2.4, while MOS SF-36 score ranged from 60.5% to 100% (mean score %). A significant (P < 0.0001) correlation was found between the score of the Viswanathan et al's questionnaire and MD (r = 0.79), Pattern Standard Deviation (PSD) (r = -0.68) and CPSD (r = -0.61).

CONCLUSION

Viswanathan et al's questionnaire was more useful than MOS SF-36, both for the score and for the velocity to use. Furthermore Viswanathan et al's questionnaire was more significantly correlated to visual field MD.

Modulating conjunctival wound healing

Advances in molecular and cell biology have led to an expansion in our knowledge and understanding of the processes involved in wound healing. We review existing and potential therapies modulating the conjunctival scarring response, with particular reference to glaucoma filtration surgery. We discuss how the refinement of present antimetabolite regimens can minimise complications and improve surgical results, and advocate their use in carefully selected patient groups. Perhaps the most promising approach is targeting biological molecules. Hence, use of fully human neutralising monoclonal antibodies to the growth factor TGF beta has potential as a useful strategy for modifying conjunctival scarring. Combination therapies may also afford an improved therapeutic index. It is hoped that future therapies can offer safer, more specific, focal and titratable treatment, with far-reaching clinical applications.

Nutrition and the eye

The topic "nutrition and the eye" cannot adequately be covered in a single review article; indeed, dozens of books and hundreds of articles have been written on the subject. This review concentrates on three areas in which specific nutrients are known or theorized to have a major impact on vision and the visual system: vitamin A deficiency; antioxidants and their proposed role in the prevention of age-related cataract and macular degeneration; and nutritional optic neuropathies, including those of the recent Cuban epidemic. In addition, this article touches on nutritional treatments that have been suggested for several less common eye diseases and, finally, considers several less prevalent conditions in which deficiency of or excess exposure to a particular nutrient has been associated with ocular pathology.

Ophthalmic and visual profile of guide dog owners in Scotland

BACKGROUND/AIMS

Out of an estimated 90,000 visually impaired people in Scotland, 509 make use of a guide dog. Initial research in Northern Ireland suggests that the ophthalmic profile of guide dog owners (GDOs) is highly specific. The aim of this study was to compare the ophthalmic and visual characteristics of Scottish GDOs with other groups of visually impaired people.

METHODS

A random sample of GDOs from central and northern Scotland (n = 82) underwent a detailed assessment of residual vision (distance and near acuity, visual fields, contrast, and glare sensitivity). Comparative data were obtained from two populations of visually impaired non-GDOs-one group attending hospital ophthalmic and low vision clinics (n = 50) the other social services rehabilitation clients (n = 35). All participants completed a questionnaire to elicit ophthalmic history, age, and registration details.

RESULTS

GDOs were found to be significantly younger and more profoundly visually impaired than non-GDOs. The main causes of visual impairment were retinitis pigmentosa (23%), optic atrophy (15%), and retinopathy of prematurity (7%). Ninety nine per cent of GDOs were registered blind and had been visually impaired for an average of 39 years. Only 31% were totally blind.

CONCLUSION

GDOs represent a unique minority of the visually impaired population. Epidemiological registration trends would suggest that the numbers of young profoundly visually impaired people are unlikely to increase relative to their elderly counterparts. This has implications on the future demand for guide dog ownership.

Understanding and controlling the scarring response: the contribution of histology and microscopy

In response to injury, the body usually initiates a full and swift wound healing response resulting in reconstructed, repaired tissue. In certain instances, due to a variety of factors, this may not happen, an example being chronic granulating venous leg ulcers. At the other extreme, the wound may heal excessively, producing disabling hypertrophic scarring such as can occur following large, deep burn injuries. Our group is interested in the surgical treatment of the eye disease glaucoma. As will be explained, the successful surgical treatment of this disease depends on a reduced scarring response at the end of wound healing. The purpose of this article is to give an overview of our microscopic and histological experimental work which has furthered our understanding of tissue repair, particularly the scarring response and its potential modification for successful glaucoma surgery.

A third locus (GLC1D) for adult-onset primary open-angle glaucoma maps to the 8q23 region

PURPOSE

Two genes for adult-onset primary open-angle glaucoma have been mapped to chromosomes 2cen-q13 and 3q21-q24. We studied a family with adult-onset primary open-angle glaucoma in which the disease did not map to these two chromosomal regions.

METHODS

We ascertained a four-generation family with adult-onset primary open-angle glaucoma in which the disease status of individuals was objectively assigned using defined criteria. Complete ophthalmologic examinations, visual field testing, optic nerve head photographs, and venous blood samples were obtained. Family members were genotyped using polymerase chain reaction amplification of microsatellite polymorphic markers. Linkage analysis was performed and lod scores were calculated. Haplotype transmission data were analyzed.

RESULTS

A total of 20 subjects in three successive generations agreed to participate in the study. This included samples from eight affected subjects, one glaucoma suspect, one normal individual, and two spouses in generations II and III, and an additional eight individuals in generation IV. The phenotype in this family appears to be variable, with onset of visual field loss in middle age, followed by modest elevation of intraocular pressure and progression of the disease in older individuals. Linkage was established with a group of DNA markers located in the 8q23 region. A lod score value of 3.61 was obtained using marker D8S1471. Three other markers from the same region gave lod score values of over 3.0. Haplotype transmission data identified two recombination events that placed the gene in a 6.3-cM region flanked by D8S1830 and D8S592. The disease-bearing haplotype was inherited by eight affected subjects and three glaucoma suspects.

CONCLUSION

We present evidence for a third adult-onset primary open-angle glaucoma locus (GLC1D) on chromosome 8q23. The genetic heterogeneity of adult-onset glaucoma is evident from the multiplicity of chromosomal loci associated with this disease.

Methods for the Hong Kong Vision Study: a pilot assessment of visual impairment in adults

INTRODUCTION

The Hong Kong Vision Study (HKVS) was a pilot study to collect data on the prevalence of eye diseases and risk factors in Hong Kong using methodology comparable to that developed in America and Australia.

AIM

The main goal was: to evaluate the application of the methodology in a different culture and language; and to determine the prevalence and risk factors of eye diseases in order to design a larger study of an ethnic Chinese population.

METHOD

This study was patterned after the Melbourne Visual Impairment Project using the Chinese language in data collection and examinations.

CONCLUSION

Well-designed methodology is transferable to different cultures, languages and continents. Use of similar methodology will enable better comparisons and analyses to be made from population-based data.

Schiotz tonometry for glaucoma: are there simple alternatives?

In the period from October 1991 until August 1992, 864 eye-patients in a rural area in south-east Nigeria were examined in order to find simple parameters for the screening of glaucoma simplex. Schiotz tonometry was used as the gold standard. Investigation of the pupil-reaction with a torch, estimation of the pressure of the (closed) eye by digital palpation, and estimations of the cup/disc ratio by ophthalmoscopy can be used as an alternative.

Peripheral colour contrast thresholds in ocular hypertension and glaucoma

PURPOSE

To evaluate a new test for peripheral colour contrast sensitivity as a tool for early diagnosis of glaucoma.

PATIENTS AND METHODS

Peripheral colour contrast sensitivity was measured by a computer and colour monitor system developed by Arden and co-workers. The monitor displays an annulus subtending 25 degrees at the retina. During the test, 45 degrees of the annulus is removed in one of four quadrants. The patient is asked to identify this quadrant, first at suprathreshold levels and then as the colour contrast between the annulus and the background is varied in order to establish the threshold for identification. The tested colours were varied along the protan, deutan and tritan colour confusion axes, respectively. Thirty-three normal subjects, 22 glaucoma patients and 69 ocular hypertensive patients were examined. The ocular hypertensive patients were divided into a low risk group, a medium risk group and a high risk group.

RESULTS

The colour contrast thresholds for the glaucoma group and the high risk ocular hypertensive group were significantly (p < 0.001) higher for all three colour axes compared with the normal group. There were also significant (p < 0.05-0.001) differences for all axes between the glaucoma group on the one hand and the ocular hypertensive low risk group on the other hand. There were, however, overlaps in colour contrast thresholds between all groups.

CONCLUSION

Although there is a large and statistically significant difference in average colour contrast thresholds between normals and glaucoma patients, it was difficult to find an appropriate cut-off point to separate the two groups. Further studies must clarify the influence of early stages of common diseases such as cataract, diabetes and age-related maculopathy on colour contrast sensitivity.