Amsler Grid Versus 10-2 Test in Primary Open Angle Glaucoma.

Background: Glaucoma is the leading cause of global irreversible blindness. The goal of management in glaucoma lies in its early detection and treatment to prevent further optic neuropathy. Available equipment for early glaucoma detection is not cost-effective or readily available in resource-scarce settings such as Nigeria. Thus, there is a need for a simple cost-effective tool to detect glaucomatous central visual field (CVF) defects in all the stages of glaucoma within the community in resource scarce-settings. Aims and Objectives: The aim of this article is to determine the validity of the Amsler grid in detecting central glaucomatous visual field defects in primary open angle glaucoma (POAG). Materials and Methods: This was a cross-sectional study of follow-up glaucoma patients at a secondary eye care hospital in Nigeria. All patients had detailed ophthalmic examination in addition to 24-2 and 10-2 CVF tests and Amsler grid test. POAG was classified using the Hodapp-Parrish-Anderson criteria into mild, moderate, and severe on 24-2 CVF. The diagnostic validity of the Amsler grid was calculated using the 10-2 CVF as a reference standard. Regression analyses were performed between the Amsler grid scotoma area and 10-2 CVF parameters [mean deviation (MD), scotoma extent (SE), and scotoma mean depth (SMD)]. Results: A total of 150 eyes of 150 patients were enrolled. The sensitivity, specificity, and positive predictive value and negative predictive value of the Amsler grid compared with the 10-2 CVF was 49.5%, 95.9%, 96.2%, and 47.9%, respectively, with an area under curve of 0.7. Sensitivity increased with increasing severity (P < 0.001) from 20.0%, 31.0%, and 76.6% in mild, moderate, and severe POAG, respectively. The Amsler grid scotoma area had the strongest relationship with the 10-2 MD, followed by 10-2 SE and 10-2 SMD with a quadratic R2 of 0.579, 0.370, and 0.307, respectively. Conclusion: The Amsler grid has a low sensitivity in mild-to-moderate POAG. However, it may serve as an adjunctive tool in resource-scarce settings for detection of severe POAG in the community by primary eye care providers.

Ocular Disorders among Preschool Children in Southwest Nigeria.

PURPOSE: The aim of the study was to determine the prevalence and causes of ocular disorders among preschool children. METHODS: A multi-stage random sampling technique was used to select 560 children from a total of 9944 children aged 3-5 years attending nursery schools in the study area. Demographic and other relevant data were collected from the children. They underwent full ophthalmic evaluation including anterior and posterior segment examination as well as cycloplegic autorefraction. RESULTS: Out of the 560 children screened, 170 (30.3%) were 3 years old, 183 (32.7%) were 4 years old, while the remaining 207 (37.0%) were 5 years old. Male-to-female ratio was 1:1.1. Visual acuity was testable using Lea symbol chart in 90% of the children. Ocular disorders were found in 61 eyes of 35 children giving a prevalence of 6.3%. The most common ocular disorder among participants was refractive error (3.9%), followed by allergic conjunctivitis (1.3%). Other identified ocular disorders were strabismus (0.9%), congenital cataract (0.4%), congenital ptosis (0.4%), optic atrophy (0.4%), ectopia lentis (0.2%), and phthisis bulbi (0.2%). There was no statistically significant difference in the distribution of ocular disorders by age or gender. CONCLUSION: Screening is useful in early detection and treatment of ocular disorders in preschool children. Uncorrected refractive error which was identified as the major ocular disorder in these children is treatable. Periodic preschool vision screening would reduce the burden of uncorrected refractive error and other ocular disorders which can interfere with the learning skills of young children entering school.

Prevalence of congenital colour vision deficiency among secondary school students in Ibadan, South-West Nigeria.

AIM: The aim was to determine the prevalence and pattern of congenital colour vision deficiency among secondary school students in Ibadan, Nigeria. SUBJECTS AND METHODS: A descriptive cross-sectional study was conducted among students from three public secondary schools through a multi-staged sampling method. Ocular examination including visual acuity assessment and colour vision test with the Ishihara plate was performed for all students. Further assessment with the Farnsworth-Munsell D-15 panel was performed for those who failed the Ishihara test. RESULTS: One thousand six hundred and thirty-five students participated in the study. There were 769 (47.0%) males with mean age of 13.9 ± 1.9 years. The overall prevalence of congenital colour vision deficiency was 2.3% with prevalence of 3.8% and 0.9% in males and females, respectively, which was statistically significant (P = 0.00112), and equal proportion of deutans 11 (32.0%) and protans 12 (35.0%) ratio of 1:1.1. CONCLUSION: The prevalence of congenital colour vision deficiency among public secondary school students in Ibadan is comparable to findings in other parts of the country.

Comparison of Peribulbar with Posterior Sub-Tenon's Anesthesia in Cataract Surgery Among Nigerians.

PURPOSE: To compare the akinetic and the analgesic effects of peribulbar and posterior sub-Tenon's anesthesia in patients undergoing cataract surgery. METHODS: In a hospital-based randomized comparative interventional study, patients aged 50 years and above who underwent elective surgery for uncomplicated cataract were randomized to receive either peribulbar block or posterior sub-Tenon block. Pain during injection, surgery, and after surgery was assessed using numerical reporting scale (NRS). Limbal excursion was measured with a transparent meter rule. RESULT: A total of 152 eyes of 152 patients were studied. Peribulbar and sub-Tenon regional blocks provided comparable adequate akinesia (P = 0.06) and similar levels of analgesia (P = 0.10) during cataract surgery. Both techniques also provided similar levels of analgesia to the patient during injection and in the immediate postoperative period. Ninety-two percent of patients who had peribulbar and 97% of those who had sub-Tenon blocks reported either mild pain or no pain at all during surgery (P = 0.49). There was no report of severe pain in all patients during the stages of the surgery. Occurrence of chemosis and subconjunctival hemorrhage was more common in sub-Tenon than peribulbar anesthesia. CONCLUSIONS: This study shows that peribulbar and posterior sub-Tenon routes of administering anesthetic substances is comparable in providing adequate akinesia and analgesia for cataract surgery with minimal complications. Therefore, both techniques are effective and safe for cataract surgery among Nigerians.

Determinants of Utilization of Eye Care Services in a Rural Adult Population of a Developing Country.

PURPOSE: To describe the factors that determine the utilization of eye care services in a rural community in South-Western Nigeria. METHODS: A descriptive cross-sectional survey using a multistage sampling technique was conducted. The main outcome measure was self-reported previous consultation of an orthodox medical facility for eye care. RESULTS: The study sample included 643 participants. Only 122 (19%) respondents had previously visited orthodox facilities in search of eye care and 24% of those with presenting visual acuity <6/18 had sought eye care. Characteristics associated with previous utilization of eye care services were age of =70 years (odds ratio [OR] ≥ 1.7, P = 0.02); male gender (OR = 1.5, P = 0.04); literacy (OR = 1.7, P = 0.007); and residing close to an eye care facility (OR = 2.8, P < 0.001). Blind respondents were three times more likely to seek eye care (P < 0.001). Regression analysis revealed that factors associated with increased likelihood of utilization of eye care services included age ≥ 70 years; literacy; residence close to an eye facility; being diabetic or hypertensive; history of ocular symptoms, and blindness. CONCLUSIONS: These findings suggest that a significant proportion (75%) of adults in the study area are not utilizing eye care services and that blindness is an important determinant of utilization of eye care services. Health education and awareness campaigns about the importance and benefits of seeking eye care early, and the provision of community-based eye care programs are essential to boost the uptake of eye care services in this community as well as other rural areas of West Africa.

Effect of face washing with soap and water and cleaning with antiseptics on upper-lid bacteria of surgical eye patients.

OBJECTIVE: To determine the effect of face washing with soap and water and cleaning with povidone iodine and cetrimide/chlorhexidine gluconate (Savlon) on upper-lid bacteria. DESIGN: Prospective, nonrandomized clinical trial. PARTICIPANTS: Eighty patients attending the Eye Clinic, University College Hospital, Ibadan, Nigeria. METHODS: Eighty patients assigned to 4 groups had swabs of the upper eyelid skin taken before and after face wash with soap and water, and cleansing with Savlon and 5% povidone iodine. Specimens were cultured and Gram stained. Bacterial counts were carried out using standard techniques. RESULTS: Face washing with soap and water increased the proportion of patients with bacterial isolates from 80.0% to 87.5%. The average colony count increased from 187.1 to 318.5 colony units per mL (p = 0.02). Application of 5% povidone iodine without face washing with soap and water reduced the proportion of patients with bacterial isolates from 82.6% (mean count 196.5) to 28.6% (mean count 34.1)(p = 0.001); in comparison, the application of 5% povidone iodine after face washing with soap and water reduced the proportion from 71.4% (mean count 133.9) to 40.0% (mean count 69.0)(p = 0.01). Application of Savlon without face washing with soap and water reduced the proportion of patients with bacterial isolates from 100% (mean count 310.9) to 41.2% (mean count 19.8)(p = 0.004) compared with the application after face washing, which reduced the proportion from 89.5% (mean count 240.3) to 41.2% (mean count 82.9)(p = 0.02). CONCLUSIONS: Both povidone and Savlon are effective in reducing periocular bacteria in an African setting. Prior face washing with soap and water had no added benefit in reducing bacterial colony count.

Paratuberculosis: eradication, control and diagnostic methods.

At the beginning of the twentieth century, the dairy industry and cattle breeding organisations initiated a programme to control infectious diseases by means of a complex system of rewards and penalties. The history of programmes to control paratuberculosis in sheep, goats, and cattle in various countries is described. The vaccination of young animals (especially goats and sheep) seems to be an effective measure in the prevention of clinical paratuberculosis, although changes in management and hygiene practices are also important. A control programme for infectious cattle diseases has a number of phases (a life cycle) and different components. Two components are essential for success, namely, open and regular communication with farmers, veterinary practitioners, and other people involved, and a good registration and identification system for cattle, herds, and veterinary practitioners. The principles and different levels of control of paratuberculosis are discussed. The Dutch paratuberculosis programme is divided in two parts: an intensive programme based on test and cull and an extensive programme based on education. The intensive programme has ten herd status levels: 5 to 10 for non?suspect herds and 1 to 4 for infected herds or herds of unknown status. The higher the status, the greater the chance that a herd is free of paratuberculosis. An outline is given of the Dutch paratuberculosis programme. Diagnostic methods are summarised. Future developments regarding vaccination and control or acceptance of paratuberculosis are discussed.

Probability of and risk factors for introduction of infectious diseases into Dutch SPF dairy farms: a cohort study.

A 2-year cohort study was conducted to investigate the probability of disease introduction into Dutch dairy farms. The farms were tested regularly for diseases and were visited biannually to collect management data. Ninety-five specific pathogen-free (SPF) dairy farms were selected from a database of bovine herpesvirus type 1 (BHV1)-free farms to study the probability of, and risk factors for, introduction of BHV1, bovine viral diarrhoea virus (BVDV), Salmonella enterica subsp. enterica serotype Dublin (S. dublin), and Leptospira interrogans serovar hardjo (L. hardjo). Although most of the 95 SPF farms had a low risk on introduction of infectious diseases, one disease was introduced into 12 farms and two diseases were introduced into one farm. Three farms experienced an outbreak of BHV1, one farm an outbreak of L. hardjo, two farms BVDV, six farms S. dublin, and one farm both BHV1 and S. dublin. The total incidence rate was 0.09 (0.06-0.12) per herd-year at risk. The results suggest that the "non-outbreak" farms were significantly more closed than the "outbreak" farms. Direct animal contacts with other cattle should be avoided and professional visitors should be instructed to wear protective clothing before handling cattle.

Risk factors for introduction of BHV1 into BHV1-free Dutch dairy farms: a case-control study.

In May 1998, a compulsory eradication programme for BHV1 started in the Netherlands. In December 1999 approximately 24% of Dutch dairy farms were certified BHV1-free (Animal Health Service (AHS)). Ninety-three certified BHV1-free dairy farms participated in a cohort study that investigated the probability of introduction of infectious diseases. The probability of introduction of BHV1 was determined from March 1997 until April 1999. Ninety of these farms remained BHV1-free and could be used as control farms. From January 1997 until March 1998, BHV1 was introduced into 41 BHV1-free dairy farms in the Netherlands (case farms). Management data were collected for both cases and controls and were complete for 37 case farms and 82 control farms. For small data sets and for data in which both low and high frequencies were expected in the contingency tables, the asymptotic methods were unreliable. Our data set clearly resembled such a data set; the risk factors were rare events because the BHV1-free farms were closed farms on which few direct animal contacts occurred. Therefore, an exact stratified modelling approach was most suitable for the data. The study showed that dairy farms should prevent cattle from escaping or mingling with other cattle and that professional visitors should always wear protective farm clothing.

Control of Mycobacterium avium subsp. paratuberculosis infection in agricultural species.

Paratuberculosis or Johne's disease is a chronic intestinal disease caused by Mycobacterium avium subsp. paratuberculosis, which continues to spread in agricultural species. Control of paratuberculosis is challenging and should not be underestimated. Due to the long incubation period of the infection, disease is largely subclinical in domesticated livestock. Hence, direct effects on animal productivity and welfare are often masked and may appear insufficient to justify large investments in control programmes by individual farmers, livestock industries or governments. Furthermore, in some countries the main effects of the disease are indirect, resulting from the impact of market discrimination against herds and flocks known to be infected, or from the control measures enforced to reduce transmission. In such circumstances, producers may be unwilling to co-operate with surveillance that may detect infection in herds or flocks. As control programmes are rarely successful in eliminating the infection from a herd or flock in the short term without an aggressive and costly programme, financial and community support assists producers to deal with the challenge. Successful prevention and control depends on animal health authorities and livestock industries acquiring a good understanding of the nature and epidemiology of infection, and of the application of tools for diagnosis and control. Building support for control programmes under the leadership of the affected livestock industries is critical, as programmes are unlikely to be successful without ongoing political will, supported by funding for research, surveillance and control.

Dutch paratuberculosis programme history, principles and development.

Organised disease control started in the Netherlands in the 18th century with governmental attempts to eradicate cattle plague. At the beginning of the 20th century, the dairy industry and cattle breeding organisations initiated a programme to control infectious diseases by means of a complex system of rewards and penalties. This was also the reason for establishing the Animal Health Service in Friesland in 1919. The history of programmes to control paratuberculosis in sheep, goats, and cattle in various countries is described. The vaccination of young animals seems to be an effective measure in the prevention of clinical paratuberculosis, although changes in management and hygiene practices are also important. A control programme for infectious cattle diseases has a number of phases (a lifecycle) and different components. Two components are essential for success, namely: open and regular communication with farmers, veterinary practitioners, and other people involved and a good registration and identification system for cattle, herds, and veterinary practitioners. The Dutch paratuberculosis programme has 10 herd status levels: 5-10 for non-suspect herds and 1-4 for infected herds or herds of unknown status. The higher the status, the greater the chance that a herd is free of paratuberculosis. An outline is given of the Dutch paratuberculosis programme including its objectives, basic principles for eradication, communication plan, legal action, logistic considerations, and complementary research programme.

Management practices associated with the incidence rate of clinical mastitis.

Risk factors for the incidence rate of clinical mastitis were studied in 274 Dutch dairy herds. Variables that were associated with resistance to disease were the feeding, housing, and milking machine factors. Variables that were associated with exposure were grazing, combined housing of dry cows and heifers, and calving area hygiene. Postmilking teat disinfection in herds with a low bulk milk somatic cell count and years of practicing dry cow therapy were positively associated with the incidence rate of clinical mastitis. Herds with a low bulk milk somatic cell count and in which postmilking teat disinfection was not used had lower incidence rates of clinical mastitis than did other herds. The incidence rate of clinical mastitis caused by Escherichia coli was mostly related to housing conditions, hygiene, and machine milking. The incidence rate of clinical mastitis caused by Staphylococcus aureus was mostly related to factors associated with bulk milk somatic cell count and factors that might be due to cause and effect reversal. A strong positive correlation existed between the incidence rate of clinical mastitis caused by Streptococcus dysgalactiae and the incidence rate of clinical mastitis caused by Staph. aureus. The incidence rate of clinical mastitis caused by Streptococcus dysgalactiae was related to nutrition, milking technique, and machine milking. The incidence rate of clinical mastitis caused by Streptococcus uberis was associated with factors related to housing, nutrition, and machine milking.

Management style and its association with bulk milk somatic cell count and incidence rate of clinical mastitis.

Management style and its association with bulk milk somatic cell count (SCC) and the incidence rate of clinical mastitis were studied in 300 Dutch dairy herds. Cluster analysis was used to identify groups of farmers who had similar management styles for the prevention of mastitis. Two groups of farmers could be differentiated. The management style of the first group of farmers was described as clean and accurate; the management style of the second group of farmers was described as quick and dirty. The relationship between clusters and the bulk milk SCC category was high. The relationship between clusters and incidence rate of clinical mastitis was weak. Compared with herds with a high (250,000 to 400,000 cells/ml) bulk milk SCC, herds with a low bulk milk SCC (< or = 150,000 cells/ml) were managed by farmers who were younger, had children with a higher education, and were more eager to invest. Farmers of herds with a low bulk milk SCC kept better records and were more familiar with each cow in their herds. The most striking difference between farmers of herds with low and high bulk milk SCC was that the first group worked precisely rather than fast; the latter group of farmers worked quickly rather than precisely. As a result, the farms with herds that had a low bulk milk SCC had better hygienic conditions than those farms with herds that had a high bulk milk SCC. We also discuss the implications for producer education with regard to udder health.

Management practices associated with low, medium, and high somatic cell counts in bulk milk.

Management practices associated with bulk milk somatic cell counts (SCC) were studied for 201 dairy herds grouped into three categories according to bulk milk SCC. The cumulative production of fat-corrected milk over 305 d of lactation and category for bulk milk SCC were highly correlated; herds within the low category had the highest milk production. Differences in bulk milk SCC among the categories were well explained by the management practices studied. This correlation was not only true for the difference between the high (250,000 to 400,000) and low (< or = 150,000) categories for bulk milk SCC but also for the difference between the medium (150,000 to 250,000) and low categories and the high and medium categories. Management practices that are known to be important for herds in the high category for bulk milk SCC, such as dry cow treatment, milking technique, postmilking teat disinfection, and antibiotic treatment of clinical mastitis, were also found to be important in the explanation of the difference between herds in the medium and low categories for bulk milk SCC. More attention was paid to hygiene for herds in the low category than for herds in the medium or high category. Supplementation of the diet with minerals occurred more frequently for cows in the low category for bulk milk SCC than for cows in the medium and high categories.

Exploratory study on the economic value of a closed farming system on Dutch dairy farms.

A closed farming system may prevent the introduction of infectious diseases on to dairy farms and could be a good starting point for the eradication of these diseases. In order to introduce a closed farming system, farmers need to be made aware of how these diseases are introduced into the herd. Farmers will be more likely to implement a closed farming system when the economic value is quantified and attractive. An exploratory study was carried out to investigate the technical and economic results of closed dairy farms. Farms that purchased cattle and/or shared pasture (defined as 'open' farms) differed in technical results from farms that did not ('closed' farms). The results of the discriminant analysis showed that the 'closed' farms incurred lower costs for veterinary services, had a lower average age at first calving and a higher birth rate per 100 dairy cows. A linear regression analysis was carried out to investigate the influence of the farming system on economic performance. Being 'closed' was found to increase the net profit by 0.31 Pound per 100 kg of milk, or approximately 25 Pounds per cow per year or 5 per cent of the typical net return to labour and management (1 Pound = Dfl 2.80 in November 1996).

[Introduction of BHV1 on dairy farms. Risk assessment by cattle farmers and veterinarians]. / Insleep van IBR op melkveebedrijven. De beoordeling van de risico's van veehouders en dierenartsen.

A study is being carried out at Wageningen Agricultural University together with, among others, the Animal Health Service to determine the possibilities and economic consequences of a more closed farming system for (Dutch) dairy farms. Three identical workshops, held in the evening, were organized as part of the study. The opinion of farmers and their veterinarians on the importance of risk factors for the introduction of diseases on a farm was determined, using Bovine Herpes Virus type 1 (BHV1) as an example. In total, 27 farmers and 13 veterinarians participated in the workshops and completed a computerized questionnaire that was based on Adapted Conjoint Analysis (ACA). The results of the farmers and veterinarians were compared. Both farmers and veterinarians seemed well aware of the risk of direct animal contacts for introduction of BHV1. Farmers thought visitors to be of more risk than veterinarians. By making use of information obtained from the ACA workshops, it will be possible to improve the advice given to different groups in the dairy sector.

Incidence of clinical mastitis in dairy herds grouped in three categories by bulk milk somatic cell counts.

Incidence of clinical mastitis was studied in 274 herds grouped in three categories by bulk milk somatic cell count (SCC). Mean incidence rate of clinical mastitis was 0.278, 0.257, and 0.252 cases per 365 cow-days at risk in herds with low (< or = 150,000), medium (150,000 to 250,000), and high (250,000 to 400,000 cells/ml) bulk milk SCC, respectively. The incidence rate of clinical mastitis was not different among the three categories. Variance in the incidence of clinical mastitis among herds increased as bulk milk SCC decreased. Clinical mastitis caused by Gram-negative pathogens, such as Escherichia coli, Klebsiella spp., or Pseudomonas spp., occurred more often in herds with a low bulk milk SCC. Clinical mastitis caused by Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus agalactiae occurred more often in herds with a high bulk milk SCC. Systemic signs of illness caused by clinical mastitis occurred more often in herds with a low bulk milk SCC. Both overall culling rate and culling rate for clinical mastitis were not different among groups catergorized by bulk milk SCC. In herds with a high bulk milk SCC, however, more cows that produced milk with a high SCC were culled. In herds with a low bulk milk SCC, more cows were culled for teat lesions, milkability, udder shape, fertility, and character than were cows in herds with a high bulk milk SCC. In herds with a low bulk milk SCC, cows were also culled more for export and production reasons.

Adaptive conjoint analysis to determine perceived risk factors of farmers, veterinarians and AI technicians for introduction of BHV1 to dairy farms.

A study was carried out to determine the possibility of a more-closed farming system for (Dutch) dairy farms. The objective of the study was to provide effective and economically profitable management advice for improving the animal-health status of farms. Management measures will only be successfully applied if supported by farmers and their advisors (such as veterinarians). Therefore, the perception of farmers and advisors of the importance of various risk factors for the introduction of diseases to a farm was determined by using bovine herpes virus type 1 (BHV1) as an example. As part of the study, an evening-long workshop was organized and run thrice. In total, 49 farmers, veterinarians and AI technicians participated in these workshops. The computerized questionnaire technique was based on adaptive conjoint analysis (ACA). ACA has the advantage that participants can work with a large number of risk factors in a relatively short period of time. Another advantage of ACA (compared with standard questionnaires) is that the answers from each participant can be checked with regard to consistency with respect to the importance assigned to them. Data from participants with inconsistent responses can be excluded from further analyses. The results of the ACA interview were compared with the risk factors reported in the literature as being associated with BHV1 status (e.g. purchase of cattle, participation in cattle shows) and with farmers' actual management to prevent the introduction of diseases. The workshop participants were all operating in the dairy sector and they seemed well aware of the risk of direct animal contacts for the introduction of BHV1. Farmers thought visitors to be more risky than did AI technicians and (especially) veterinarians. Farmers who purchased cattle or participated in cattle shows were of the opinion that the risks of direct animal contacts were more important than did farmers who were not involved in those practices. Farmers whose farms were BHV1-positive (and participated in cattle shows more often) thought the risk of participation smaller than did farmers with BHV1-negative farms.

Effect of freezing on somatic cell count of quarter milk samples as determined by a Fossomatic electronic cell counter.

The objective of this study was to determine the effect of freezing and the duration of freezing on somatic cell count (SCC) in milk samples from quarters with no signs of clinical mastitis. Effect was determined by a fluoro-opto-electronic cell counter. Samples were frozen in a commercial freezer at approximately -20 degrees C. The milk samples were thawed at 1, 2, 3, 4, 7, 14, or 28 d. Another batch of samples was frozen 1 d, thawed, frozen again for 1 d, and then thawed. The SCC was determined on the fresh samples and after any one of the freezing periods. On average, the SCC were lower after all freezing periods than they were before freezing. However, the difference in SCC before and after freezing was small and relatively constant on the natural logarithm scale. The decrease in SCC was larger with longer freezing periods. When SCC thresholds of 200,000, 250,000, and 500,000 cells/ml were used to predict infection, freezing appeared to have little impact on the sensitivity and specificity of diagnostic parameters. Therefore, SCC, as determined by a fluoro-opto-electronic cell counter, determined for frozen quarter milk samples can be used in mastitis control and research programs.