The protective variant rs7173049 at LOXL1 locus impacts on retinoic acid signaling pathway in pseudoexfoliation syndrome

LOXL1 (lysyl oxidase-like 1) has been identified as the major effect locus in pseudoexfoliation (PEX) syndrome, a fibrotic disorder of the extracellular matrix and frequent cause of chronic open-angle glaucoma. However, all known PEX-associated common variants show allele effect reversal in populations of different ancestry, casting doubt on their biological significance. Based on extensive LOXL1 deep sequencing, we report here the identification of a common non-coding sequence variant, rs7173049A>G, located downstream of LOXL1, consistently associated with a decrease in PEX risk (odds ratio, OR = 0.63; P = 6.33 × 10⁻³¹) in nine different ethnic populations. We provide experimental evidence for a functional enhancer-like regulatory activity of the genomic region surrounding rs7173049 influencing expression levels of ISLR2 (immunoglobulin superfamily containing leucine-rich repeat protein 2) and STRA6 [stimulated by retinoic acid (RA) receptor 6], apparently mediated by allele-specific binding of the transcription factor thyroid hormone receptor beta. We further show that the protective rs7173049-G allele correlates with increased tissue expression levels of ISLR2 and STRA6 and that both genes are significantly downregulated in tissues of PEX patients together with other key components of the STRA6 receptor-driven RA signaling pathway. siRNA-mediated downregulation of RA signaling induces upregulation of LOXL1 and PEX-associated matrix genes in PEX-relevant cell types. These data indicate that dysregulation of STRA6 and impaired retinoid metabolism are involved in the pathophysiology of PEX syndrome and that the variant rs7173049-G, which represents the first common variant at the broad LOXL1 locus without allele effect reversal, mediates a protective effect through upregulation of STRA6 in ocular tissues.

Association of Rare CYP39A1 Variants With Exfoliation Syndrome Involving the Anterior Chamber of the Eye

IMPORTANCE

Exfoliation syndrome is a systemic disorder characterized by progressive accumulation of abnormal fibrillar protein aggregates manifesting clinically in the anterior chamber of the eye. This disorder is the most commonly known cause of glaucoma and a major cause of irreversible blindness.

OBJECTIVE

To determine if exfoliation syndrome is associated with rare, protein-changing variants predicted to impair protein function.

DESIGN, SETTING, AND PARTICIPANTS

A 2-stage, case-control, whole-exome sequencing association study with a discovery cohort and 2 independently ascertained validation cohorts. Study participants from 14 countries were enrolled between February 1999 and December 2019. The date of last clinical follow-up was December 2019. Affected individuals had exfoliation material on anterior segment structures of at least 1 eye as visualized by slit lamp examination. Unaffected individuals had no signs of exfoliation syndrome.

EXPOSURES

Rare, coding-sequence genetic variants predicted to be damaging by bioinformatic algorithms trained to recognize alterations that impair protein function.

MAIN OUTCOMES AND MEASURES

The primary outcome was the presence of exfoliation syndrome. Exome-wide significance for detected variants was defined as P < 2.5 × 10-6. The secondary outcomes included biochemical enzymatic assays and gene expression analyses.

RESULTS

The discovery cohort included 4028 participants with exfoliation syndrome (median age, 78 years [interquartile range, 73-83 years]; 2377 [59.0%] women) and 5638 participants without exfoliation syndrome (median age, 72 years [interquartile range, 65-78 years]; 3159 [56.0%] women). In the discovery cohort, persons with exfoliation syndrome, compared with those without exfoliation syndrome, were significantly more likely to carry damaging CYP39A1 variants (1.3% vs 0.30%, respectively; odds ratio, 3.55 [95% CI, 2.07-6.10]; P = 6.1 × 10-7). This outcome was validated in 2 independent cohorts. The first validation cohort included 2337 individuals with exfoliation syndrome (median age, 74 years; 1132 women; n = 1934 with demographic data) and 2813 individuals without exfoliation syndrome (median age, 72 years; 1287 women; n = 2421 with demographic data). The second validation cohort included 1663 individuals with exfoliation syndrome (median age, 75 years; 587 women; n = 1064 with demographic data) and 3962 individuals without exfoliation syndrome (median age, 74 years; 951 women; n = 1555 with demographic data). Of the individuals from both validation cohorts, 5.2% with exfoliation syndrome carried CYP39A1 damaging alleles vs 3.1% without exfoliation syndrome (odds ratio, 1.82 [95% CI, 1.47-2.26]; P < .001). Biochemical assays classified 34 of 42 damaging CYP39A1 alleles as functionally deficient (median reduction in enzymatic activity compared with wild-type CYP39A1, 94.4% [interquartile range, 78.7%-98.2%] for the 34 deficient variants). CYP39A1 transcript expression was 47% lower (95% CI, 30%-64% lower; P < .001) in ciliary body tissues from individuals with exfoliation syndrome compared with individuals without exfoliation syndrome.

CONCLUSIONS AND RELEVANCE

In this whole-exome sequencing case-control study, presence of exfoliation syndrome was significantly associated with carriage of functionally deficient CYP39A1 sequence variants. Further research is needed to understand the clinical implications of these findings.

Association of Genetic Variants With Primary Open-Angle Glaucoma Among Individuals With African Ancestry

IMPORTANCE

Primary open-angle glaucoma presents with increased prevalence and a higher degree of clinical severity in populations of African ancestry compared with European or Asian ancestry. Despite this, individuals of African ancestry remain understudied in genomic research for blinding disorders.

OBJECTIVES

To perform a genome-wide association study (GWAS) of African ancestry populations and evaluate potential mechanisms of pathogenesis for loci associated with primary open-angle glaucoma.

DESIGN, SETTINGS, AND PARTICIPANTS

A 2-stage GWAS with a discovery data set of 2320 individuals with primary open-angle glaucoma and 2121 control individuals without primary open-angle glaucoma. The validation stage included an additional 6937 affected individuals and 14 917 unaffected individuals using multicenter clinic- and population-based participant recruitment approaches. Study participants were recruited from Ghana, Nigeria, South Africa, the United States, Tanzania, Britain, Cameroon, Saudi Arabia, Brazil, the Democratic Republic of the Congo, Morocco, Peru, and Mali from 2003 to 2018. Individuals with primary open-angle glaucoma had open iridocorneal angles and displayed glaucomatous optic neuropathy with visual field defects. Elevated intraocular pressure was not included in the case definition. Control individuals had no elevated intraocular pressure and no signs of glaucoma.

EXPOSURES

Genetic variants associated with primary open-angle glaucoma.

MAIN OUTCOMES AND MEASURES

Presence of primary open-angle glaucoma. Genome-wide significance was defined as P < 5 × 10-8 in the discovery stage and in the meta-analysis of combined discovery and validation data.

RESULTS

A total of 2320 individuals with primary open-angle glaucoma (mean [interquartile range] age, 64.6 [56-74] years; 1055 [45.5%] women) and 2121 individuals without primary open-angle glaucoma (mean [interquartile range] age, 63.4 [55-71] years; 1025 [48.3%] women) were included in the discovery GWAS. The GWAS discovery meta-analysis demonstrated association of variants at amyloid-β A4 precursor protein-binding family B member 2 (APBB2; chromosome 4, rs59892895T>C) with primary open-angle glaucoma (odds ratio [OR], 1.32 [95% CI, 1.20-1.46]; P = 2 × 10-8). The association was validated in an analysis of an additional 6937 affected individuals and 14 917 unaffected individuals (OR, 1.15 [95% CI, 1.09-1.21]; P < .001). Each copy of the rs59892895*C risk allele was associated with increased risk of primary open-angle glaucoma when all data were included in a meta-analysis (OR, 1.19 [95% CI, 1.14-1.25]; P = 4 × 10-13). The rs59892895*C risk allele was present at appreciable frequency only in African ancestry populations. In contrast, the rs59892895*C risk allele had a frequency of less than 0.1% in individuals of European or Asian ancestry.

CONCLUSIONS AND RELEVANCE

In this genome-wide association study, variants at the APBB2 locus demonstrated differential association with primary open-angle glaucoma by ancestry. If validated in additional populations this finding may have implications for risk assessment and therapeutic strategies.

Familial congenital cataract, coloboma, and nystagmus phenotype with variable expression caused by mutation in PAX6 in a South African family

Purpose

To report on a clinical and genetic investigation of a large, multigenerational South African family of mixed ancestry with autosomal dominant congenital cataracts, coloboma, and nystagmus.

Methods

Ophthalmic examination was performed in 27 individuals from the same admixed South African family. DNA was sampled from either peripheral blood or buccal swabs in all 27 individuals, and whole genome sequencing was performed in six individuals. Sanger sequencing was used to validate the probable mutation in the remaining family members.

Results

Twenty-seven family members with 19 affected individuals were included in the study. The predominant phenotype, with highly variable expression, was congenital cataract (14 individuals), posterior segment coloboma (17 individuals), and nystagmus (18 individuals). Other features present included high myopia, microcornea, and strabismus. An R208W mutation in PAX6 (dbSNP rs757259413; HGMD CM930572; NM_000280.3:c.622G>A; NP_000271.1:p.Arg208Trp) was identified as being the most probable pathogenic mutation. Cosegregation of the mutation with the phenotype was confirmed in all 27 family members.

Conclusions

PAX6 is a highly conserved gene crucial for normal oculogenesis, and although mutations within the gene may cause an array of ocular developmental abnormalities, most are associated with aniridia and aniridia-related ocular defects. The observation that PAX6 aniridia phenotypes are largely associated with nonsense mutations and milder non-aniridia phenotypes with missense mutations suggested that there may be specific genotype-phenotype correlations for the gene. The R208W mutation in PAX6 identified in this family challenges this theory as it has previously been reported in three unrelated families and is associated with aniridia and non-aniridia phenotypes across the four families. PAX6 with its wide phenotypic associations and highly variable expression should be considered a candidate gene in the diagnostic screen for any ocular developmental abnormality.

Genetic association study of exfoliation syndrome identifies a protective rare variant at LOXL1 and five new susceptibility loci

Exfoliation syndrome (XFS) is the most common known risk factor for secondary glaucoma and a major cause of blindness worldwide. Variants in two genes, LOXL1 and CACNA1A, have previously been associated with XFS. To further elucidate the genetic basis of XFS, we collected a global sample of XFS cases to refine the association at LOXL1, which previously showed inconsistent results across populations, and to identify new variants associated with XFS. We identified a rare protective allele at LOXL1 (p.Phe407, odds ratio (OR) = 25, P = 2.9 × 10^-14) through deep resequencing of XFS cases and controls from nine countries. A genome-wide association study (GWAS) of XFS cases and controls from 24 countries followed by replication in 18 countries identified seven genome-wide significant loci (P < 5 × 10^-8). We identified association signals at 13q12 (POMP), 11q23.3 (TMEM136), 6p21 (AGPAT1), 3p24 (RBMS3) and 5q23 (near SEMA6A). These findings provide biological insights into the pathology of XFS and highlight a potential role for naturally occurring rare LOXL1 variants in disease biology.

Genetic variants and cellular stressors associated with exfoliation syndrome modulate promoter activity of a lncRNA within the LOXL1 locus

Exfoliation syndrome (XFS) is a common, age-related, systemic fibrillinopathy. It greatly increases risk of exfoliation glaucoma (XFG), a major worldwide cause of irreversible blindness. Coding variants in the lysyl oxidase-like 1 (LOXL1) gene are strongly associated with XFS in all studied populations, but a functional role for these variants has not been established. To identify additional candidate functional variants, we sequenced the entire LOXL1 genomic locus (∼40 kb) in 50 indigenous, black South African XFS cases and 50 matched controls. The variants with the strongest evidence of association were located in a well-defined 7-kb region bounded by the 3'-end of exon 1 and the adjacent region of intron 1 of LOXL1. We replicated this finding in US Caucasian (91 cases/1031 controls), German (771 cases/1365 controls) and Japanese (1484 cases/1188 controls) populations. The region of peak association lies upstream of LOXL1-AS1, a long non-coding RNA (lncRNA) encoded on the opposite strand of LOXL1. We show that this region contains a promoter and, importantly, that the strongly associated XFS risk alleles in the South African population are functional variants that significantly modulate the activity of this promoter. LOXL1-AS1 expression is also significantly altered in response to oxidative stress in human lens epithelial cells and in response to cyclic mechanical stress in human Schlemm's canal endothelial cells. Taken together, these findings support a functional role for the LOXL1-AS1 lncRNA in cellular stress response and suggest that dysregulation of its expression by genetic risk variants plays a key role in XFS pathogenesis.

Bee sting of the cornea: A running case report

Bee stings that present with ocular sequelae are infrequently reported in the literature. The present report is of a retained corneal bee stinger with a delayed presentation. A review of case reports reveals a number of potential ocular complications of bee stings. The ocular sequelae and treatment options are reviewed.

The genetics of POAG in black South Africans: a candidate gene association study

Multiple loci have been associated with either primary open angle glaucoma (POAG) or heritable ocular quantitative traits associated with this condition. This study examined the association of these loci with POAG, with central corneal thickness (CCT), vertical cup-to-disc ratio (VCDR) and with diabetes mellitus in a group of black South Africans (215 POAG cases and 214 controls). The population was homogeneous and distinct from other African and European populations. Single SNPs in the MYOC, COL8A2, COL1A1 and ZNF469 gene regions showed marginal associations with POAG. No association with POAG was identified with tagging SNPs in TMCO1, CAV1/CAV2, CYP1B1, COL1A2, COL5A1, CDKN2B/CDKN2BAS-1, SIX1/SIX6 or the chromosome 2p16 regions and there were no associations with CCT or VCDR. However, SNP rs12522383 in WDR36 was associated with diabetes mellitus (p = 0.00008). This first POAG genetic association study in black South Africans has therefore identified associations that require additional investigation in this and other populations to determine their significance. This highlights the need for larger studies in this population if we are to achieve the goal of facilitating early POAG detection and ultimately preventing irreversible blindness from this condition.

The role of lysyl oxidase-like 1 DNA copy number variants in exfoliation glaucoma

PURPOSE

To investigate whether DNA copy number variants (CNVs) in the lysyl oxidase-like 1 (LOXL1) gene are associated with exfoliation glaucoma (XFG) in black South Africans.

METHODS

Black South African subjects with XFG and age-matched unaffected controls were recruited from the St. John Eye Hospital in Soweto (Johannesburg, South Africa) and East London Hospital Complex (Eastern Cape, South Africa) using standard clinical examination techniques. A customized array comparative genomic hybridization (aCGH) from Roche NimbleGen was designed to cover a 1.5 million base genomic region centered on the LOXL1 gene on chromosome 15. Twenty selected XFG cases were examined using this custom aCGH to identify common CNVs in the LOXL1 gene. The potential DNA copy number variants identified from aCGH were further validated using TaqMan probe-based CNV real-time PCR in a data set containing 91 XFG cases and 52 controls. The frequencies of CNVs in the LOXL1 region were compared between the XFG cases and the controls using Fisher's exact test.

RESULTS

Several DNA CNV variants were identified in the LOXL1 genomic region using aCGH in the selected XFG cases. However, we were unable to validate these candidate CNVs using real-time PCR-based TaqMan CNV assays. There was no significant difference in the frequency of the DNA copy number variants in the LOXL1 region between the XFG cases and the controls.

CONCLUSIONS

This represents the first DNA CNV study of LOXL1 in the black South African population with XFG. Our study did not identify any significant DNA copy number alterations in the genomic region containing the LOXL1 gene. This suggests that other as yet unknown causal variants of LOXL1 or variants in other genes in linkage disequilibrium with the LOXL1 locus contribute to the genetic risk of XFG in black South Africans.

Micromechanical and physical stability analysis of an irradiated poly (lactic-co-glycolic acid) donut-shaped minitablet device for intraocular implantation

This study pragmatically characterized the micromechanical and physical stability of a poly(lactic-co-glycolic acid) (PLGA)-based ganciclovir (GCV)-loaded donut-shaped minitablet (DSMT) device for intraocular implantation. Thermal and spectroscopic analysis was performed on various drug-polymer permutations. Porositometric profiles were quantitatively analyzed coupled with qualitatively SEM imaging. The tensile strength (TS) and fracture energy (FE) of the device was also determined pre- and post-γ-sterilization. Inimitably, chemometric and molecular modeling provided a supportive confirmatory tool for establishing fundamental correlative suppositions between the transitioned surface morphology and the micromechanical stability after γ-irradiation. Isotherm plot volumes ranged between -0.028 ± 0.022 and 0.110 ± 0.005 m(2)/g for pre- and post-sterilized devices, respectively, revealing a microporous alteration in porosity. Pre-sterilized devices had larger pores (BJHa=286.22 vs. 192.49 Å) and lower FE (151.301 ± 6.089 N/m) and TS (26.396 ± 1.062 N) values while sterilized devices had crystalline matrices that facilitated the superiorly controlled drug release kinetcs obtained. DSC thermograms displayed the characteristic disordered crystallization of GCV and hydration exotherms resulting from ionization during γ-irradiation. FTIR spectrograms showed fingerprint molecular imprints of GCV and axial stretching of hybridized carbons of PLGA with no subversive drug-polymer interactions after γ-irradiation. Integration of the results inveterately revealed that compression and subsequent γ-irradiation of the device affected desirable micromechanical and solid-state stability behavior.

Myocilin mutations in black South Africans with POAG

PURPOSE

Myocilin (MYOC) mutations are associated with primary open-angle glaucoma (POAG) in multiple populations. Here we examined the role of MYOC mutations in a black South African population with primary open-angle glaucoma (POAG).

METHODS

Unrelated black South African subjects with POAG and unaffected controls were recruited from the St. John Eye Hospital (Soweto, Johannesburg, South Africa) and East London Hospital Complex (Eastern Cape, South Africa). A complete eye examination including visual field assessment was performed in all subjects. Blood samples were obtained for DNA extraction. The complete coding region of MYOC was sequenced using the PCR-based Sanger method. Identified mutations were compared to known MYOC mutations.

RESULTS

One hundred-thirteen POAG cases and 131 controls were recruited for analysis. A total of 19 variants were observed. Probable glaucoma-causing mutations were observed in 4.4% of POAG cases. A previously reported glaucoma-causing mutation, Tyr453MetfsX11, was observed in three cases and one control. Two other sequence variants, Gly374Val and Lys500Arg, occurred only in cases. Other sequence variants, including 6 novel variants, occurred in at least one control.

CONCLUSIONS

A small minority of black South Africans with POAG carry MYOC mutations. The Gly374Val mutation might represent a novel glaucoma-causing mutation. The Tyr453MetFSX11 mutation appears to be a glaucoma-causing mutation with incomplete penetrance.

A review of implantable intravitreal drug delivery technologies for the treatment of posterior segment eye diseases

Intravitreal implantable device technology utilizes engineered materials or devices that could revolutionize the treatment of posterior segment eye diseases by affording localized drug delivery, responding to and interacting with target sites to induce physiological responses while minimizing side-effects. Conventional ophthalmic drug delivery systems such as topical eye-drops, systemic drug administration or direct intravitreal injections do not provide adequate therapeutic drug concentrations that are essential for efficient recovery in posterior segment eye disease, due to limitations posed by the restrictive blood-ocular barriers. This review focuses on various aspects of intravitreal drug delivery such as the impediment of the blood-ocular barriers, the potential sites or intraocular drug delivery device implantation, the various approaches employed for ophthalmic drug delivery and includes a concise critical incursion into specialized intravitreal implantable technologies for the treatment of anterior and posterior segment eye disease. In addition, pertinent future challenges and opportunities in the development of intravitreal implantable devices is discussed and explores their application in clinical ophthalmic science to develop innovative therapeutic modalities for the treatment of various posterior segment eye diseases. The inherent structural and functional properties, the potential for providing rate-modulated drug delivery to the posterior segment of the eye and specific development issues relating to various intravitreal implantable drug delivery devices are also expressed in this review.

Major LOXL1 risk allele is reversed in exfoliation glaucoma in a black South African population

PURPOSE

To investigate whether variants in the lysyl oxidase-like 1 (LOXL1) gene are associated with exfoliation glaucoma (XFG) and primary open-angle glaucoma (POAG) in an ancestral population from South Africa.

METHODS

Black South African subjects with XFG, POAG, and age matched unaffected controls were recruited from the St. John Eye Hospital in Soweto, Johannesburg, South Africa, using standard clinical examination techniques. Fifty individuals were collected for each of the three groups: XFG, POAG, and normal controls. The complete coding region of LOXL1 was sequenced using the PCR-based Sanger method. The allele frequencies of the identified sequence variants were compared between XFG or POAG and controls using Fisher's exact test.

RESULTS

A large number of coding variants were identified, including rs1048661 (R141L), rs3825942 (G153D), S159A, S161L, rs41435250 (A320A), rs13329473 (F489F), and T567A. The allele frequencies of both rs3825942 and rs1048661 differed significantly between the XFG and control subjects from South Africa (p=5.2 x 10(-13) and 1.7 x 10(-5), respectively). The G allele for rs1048661 (encoding arginine) was the risk allele which is similar to other populations. The A allele of rs3825942 (encoding aspartic acid) was the risk allele, in sharp contrast to the G allele (encoding glycine) reported in multiple other populations. There was no significant difference in the allele frequencies of coding variants in LOXL1 between POAG and control subjects.

CONCLUSIONS

This represents the first genetic association study of LOXL1 in an ancestral African population with XFG. We have confirmed the association between variants of LOXL1 and XFG. To date, the G allele of the major susceptibility variant rs3825942 has consistently been shown in multiple populations to increase the risk of XFG. Surprisingly, we have found a strong association with the opposite allele in the South African population. This suggests that other as yet unknown causal variants of LOXL1 contribute to the genetic risk of XFG.

Implantation of a Miniature Glaucoma Device Under a Scleral Flap

PURPOSE

To test the safety and efficacy of the Ex-PRESS miniature glaucoma device when it is implanted under a scleral flap instead of under the conjunctiva as it was originally suggested.

PATIENTS AND METHODS

Between November 2000 and February 2003, the Ex-PRESS implant was inserted in 24 eyes of 23 patients with severe open angle glaucoma. Sixteen eyes of the 24 (66%) had had previous failed filtering surgery. The remaining 8 eyes (33%) were high risk for failures cases. A 5 x 5 mm limbal-based, 50% depth, scleral flap was raised into clear cornea. The Ex-PRESS implant was inserted into the anterior chamber under the scleral flap at the limbus. The scleral flap was securely sutured back, as is done in trabeculectomy operations.

RESULTS

The intraocular pressure was significantly reduced from 27.2 +/- 7.1 mm Hg pre-operatively to 14.5 +/- 5.0 mm Hg at 12 months (n = 21) and 14.2 +/- 4.2 mm Hg at 24 months (n = 8). Postoperatively, only two patients needed anti-glaucoma medications to keep the IOP below 21 mm Hg.

CONCLUSIONS

The Ex-PRESS device was found to be safe and effective with few complications when it is implanted under a scleral flap even in the high-risk patients studied.

Effective and accurate screening for diabetic retinopathy using a 60 degree mydriatic fundus camera

OBJECTIVES. To establish whether an experienced endocrinologist could screen accurately for diabetic retinopathy using mydriatic 60 degree fundus photographs compared with a reference standard, viz. the combined highest scores of two experienced ophthalmologists.

DESIGN

Retrospective review of 60 degree colour transparency photographs taken over a 6-year period. Retinopathy was graded in a standardised way.

SETTING

Patients attending the diabetic clinic at Johannesburg Hospital, South Africa.

SUBJECTS

Fifteen hundred and seventeen patients (2446 eyes) formed the basis for the study. Patients were included if there was more than 50% readability of the fundus photographs.

OUTCOME MEASURES

Outcome measures were prevalence of any retinopathy and presence of referable (severe) retinopathy. Interobserver agreement was measured using the kappa statistic, and sensitivity and specificity of the screener were evaluated.

RESULTS

The prevalence of retinopathy at the clinic was approximately 30%, but only about 12% was severe enough to warrant referral to the ophthalmology outpatient department. The endocrinologist was very accurate in determining cases requiring referral; there was 97% agreement with the reference standard, viz. the combined highest score of two experienced ophthalmologists (gold standard). Correlation on the determination of any retinopathy was less accurate (80% agreement), mostly owing to the endocrinologist reporting more isolated microaneurysms than the ophthalmologists. The screening method used gave a sensitivity of 83% and specificity of 99% which are within recommended standards.

CONCLUSIONS

The screening strategy using a mydriatic fundus camera at the diabetic clinic was found to be effective and accurate and greatly reduced the number of possible referrals to the ophthalmology outpatient department.

Clinical evaluation of twice-daily emedastine 0.05% eye drops (Emadine eye drops) versus levocabastine 0.05% eye drops in patients with allergic conjunctivitis

PURPOSE

The efficacy and safety of emedastine 0.05% eye drops (Emadine; Alcon Laboratories, Inc, Fort Worth, Texas), a new H(1) antagonist, were studied in comparison to levocabastine 0.05% eye drops (Livostin; Janssen-Cilag N V, Berchem, Belgium) during a twice-daily treatment schedule for 6 weeks in adult and pediatric patients with seasonal allergic conjunctivitis.

METHODS

In a prospective, multicenter, randomized, double-masked, parallel group study, 222 patients with allergic conjunctivitis were randomized (221 received treatment) to either emedastine or levocabastine, instilled twice daily for 6 weeks. Patient diaries were completed four times daily (before the morning and evening instillations, at noon, and in the afternoon), and clinical examinations were conducted at regular intervals. Primary efficacy variables of ocular redness and itching and secondary efficacy variables of chemosis, eyelid swelling, patient diary data, and physician's global assessment were analyzed.

RESULTS

Both emedastine and levocabastine produced a statistically significant (P =.0001) reduction in itching and redness within 5 minutes of the first instillation. All signs and symptoms improved progressively over the 6-week treatment period. After 7 days of use, and throughout the remainder of the study, emedastine was statistically superior to levocabastine (P <.006) in preventing and alleviating the signs and symptoms (itching, redness, chemosis, and eyelid swelling) of allergic conjunctivitis.

CONCLUSIONS

Emedastine 0.05% eye drops administered twice daily are more efficacious than levocabastine 0.05% eye drops in the prevention and treatment of the signs and symptoms of allergic conjunctivitis in adults and children of 4 years and above. Both emedastine 0.05% eye drops and levocabastine 0.05% eye drops were well tolerated.

Topical steroids in the treatment of central and paracentral corneal ulcers

During an 18-month period a prospective randomised trial was conducted on 40 selected patients with bacterial corneal ulcers. Two groups were compared: one was treated with antibiotic only and the other with antibiotic plus steroid. Complications were similar in the two groups. No delay in healing rate of the ulcers was seen with the use of topical steroid. Two methods of assessing visual improvement are discussed, but it was not possible to demonstrate a difference in visual outcome between the two groups.

Factors predisposing to central corneal ulceration in a developing population

Over a 1-year period all patients presenting to St John's Eye Hospital with corneal ulceration were studied. The local and general factors predisposing to central (primarily infective) corneal ulceration are discussed. Episodes of corneal trauma and climatic droplet keratopathy were the major local factors and these occurred against the background of a generally poor nutritional status.

Use of contrast sensitivity measurement in the detection of subclinical ethambutol toxic optic neuropathy

Contrast sensitivity was measured by means of Arden grating plates in 100 patients on medication for pulmonary tuberculosis. The scores were abnormal in 38.2% of the patients whose therapy included ethambutol for three months, and 36.7% of the patients on similar treatment for six months. In comparison with age matched groups of patients on a regimen where streptomycin replaced ethambutol a statistically significant number of the patients on ethambutol had abnormal scores. This study suggests that Arden contrast sensitivity plates would be effective in detecting subclinical toxic optic neuropathy due to ethambutol and therefore could be used for routine monitoring of ocular function of patients on ethambutol. Loss of contrast sensitivity may explain why some patients on ethambutol with normal visual acuity and colour perception may still complain of visual disturbance.

Corneal ulceration at an urban African hospital

During a one-year survey 283 corneal ulcers from 274 patients were seen at St John's Eye Unit of Baragwanath Hospital. Central bacterial ulcers constituted the largest problem, and the commonest isolate in this group was Streptococcus pneumoniae. Mycotic and dendritic keratitis were relatively uncommon, while marginal catarrhal ulceration secondary to chronic staphylococcal lid disease was frequently seen. The microbiology of the various ulcers is described, and the placing of organisms into classes is stressed in determining significance of isolates. Many of the patients were male Africans who were either manual labourers or unemployed. Half the patients had used topical antibiotics before presentation.

Measles notifications -- the first year

Measles is a major cause of childhood mortality in the developing world. Observed trends in the USA confirm the efficacy of a measles control programme. South Africa launched such a programme in 1975 with the introduction of free vaccine for all children. In order to enhance and monitor this campaign, measles became a notifiable condition on 24 August 1979. Notifications received in the first year are reviewed and the observed patterns are discussed.

Blinding trachoma--a public health challenge

Trachoma constitutes a public health problem in several areas of the RSA. The epidemiology of trachoma is examined. The notifications of trachoma for the past decade are presented and the value of notification of this disease is discussed. Control of blindness due to trachoma may be achieved by involving the community in which it occurs.

The spread of cholera in South Africa

The current cholera epidemic in the RSA began in October 1980 and is part of the seventh pandemic. Initial investigation of the epidemic revealed a virtually closed system of water supply, which explained the distribution of the early cases. The spread of cholera in the RSA is examined and local factors contributing to cholera transmission are discussed. Attempts are being made to prevent cholera from becoming endemic in the RSA and long-term improvements in health facilities in the susceptible areas of the country are being undertaken.

Problems in eradicating poliomyelitis from South Africa

The number of poliomyelitis notifications in South Africa has declined in recent years although small outbreaks continue to occur. The feasibility of total eradication of the wild virus from the RSA is examined.