Anaerobic dihydrogen consumption of nutrient-limited aquifer sediment microbial communities examined by stable isotope analysis

The biogeochemical consequences of dihydrogen (H2) underground storage in porous aquifers are poorly understood. Here, the effects of nutrient limitations on anaerobic H2 oxidation of an aquifer microbial community in sediment microcosms were determined in order to evaluate possible responses to high H2 partial pressures. Hydrogen isotope analyses of H2 yielded isotope depletion in all biotic setups indicating microbial H2 consumption. Carbon isotope analyses of carbon dioxide (CO2) showed isotope enrichment in all H2-supplemented biotic setups indicating H2-dependent consumption of CO2 by methanogens or homoacetogens. Homoacetogenesis was indicated by the detection of acetate and formate. Consumption of CO2 and H2 varied along the differently nutrient-amended setups, as did the onset of methane production. Plotting carbon against hydrogen isotope signatures of CH4 indicated that CH4 was produced hydrogenotrophically and fermentatively. The putative hydrogenotrophic Methanobacterium sp. was the dominant methanogen. Most abundant phylotypes belonged to typical ferric iron reducers, indicating that besides CO2, Fe(III) was an important electron acceptor. In summary, our study provides evidence for the adaptability of subsurface microbial communities under different nutrient-deficient conditions to elevated H2 partial pressures.

Demystifying mercury geochemistry in contaminated soil-groundwater systems with complementary mercury stable isotope, concentration, and speciation analyses

Interpretation of mercury (Hg) geochemistry in environmental systems remains a challenge. This is largely associated with the inability to identify specific Hg transformation processes and species using established analytical methods in Hg geochemistry (total Hg and Hg speciation). In this study, we demonstrate the improved Hg geochemical interpretation, particularly related to process tracing, that can be achieved when Hg stable isotope analyses are complemented by a suite of more established methods and applied to both solid- (soil) and liquid-phases (groundwater) across two Hg²⁺-chloride (HgCl₂) contaminated sites with distinct geological and physicochemical properties. This novel approach allowed us to identify processes such as Hg²⁺ (i.e., HgCl₂) sorption to the solid-phase, Hg²⁺ speciation changes associated with changes in groundwater level and redox conditions (particularly in the upper aquifer and capillary fringe), Hg²⁺ reduction to Hg⁰, and dark abiotic redox equilibration between Hg⁰ and Hg(II). Hg stable isotope analyses play a critical role in our ability to distinguish, or trace, these in situ processes. While we caution against the non-critical use of Hg isotope data for source tracing in environmental systems, due to potentially variable source signatures and overprinting by transformation processes, our study demonstrates the benefits of combining multiple analytical approaches, including Hg isotope ratios as a process tracer, to obtain an improved picture of the enigmatic geochemical behavior and fate of Hg at contaminated legacy sites.

Video Analysis of Pectoralis Major Injuries in Professional Australian Football Players

Background:

There is little evidence regarding the mechanisms of pectoralis major (PM) injury and player outcomes in Australian Football League (AFL) players.

Purposes/Hypothesis:

The study aims were to investigate (1) the mechanisms of PM muscle injury in elite AFL players via video analysis and (2) the player profile, method of management, and clinical outcomes of the PM injuries sustained. We hypothesized that the majority of PM tears would occur in outer-range PM positions (hyperextension of the glenohumeral joint).

Study Design:

Case series; Level of evidence, 4.

Methods:

We analyzed video of the precipitating event for traumatic PM injuries during AFL competition or training over a 20-year period (2002-2021). The footage was analyzed by 4 experienced assessors, and the following were evaluated: mechanism of injury, injury variables (arm position, initial contact point, visual awareness, and use of taping), player characteristics (age at the time of injury, hand dominance, and history of injury), injury profile (location and size of tear), method of management (operative vs nonoperative), patient outcomes (time to return to full senior training/match play), and complication rates.

Results:

The mean ± standard deviation age of the players was 26.5 ± 3.1 years (range, 21-32 years). Overall, 22 PM injuries were identified in the AFL injury database for a rate of 1.1 per year; 16 of these injuries had accompanying video footage. We identified 3 mechanisms for PM injury: horizontal hyperextension (62.5%), hyperflexion-abduction (25.0%), and horizontal adduction (sustained tackling; 12.5%). The most common site of the tear was the insertion point of the sternocostal head (91.0%). Twenty players (91.0%) required surgical repair, with 75% undergoing surgery within 1 week (range, 0-26 weeks). The mean return to competition for the surgical repair group was 11.1 weeks (range, 8-15 weeks). The rerupture rate was 5.0% (1 repair; <4 weeks postoperatively in 2004).

Conclusion:

PM tears in elite male AFL players were due to 1 of 3 distinct mechanisms: horizontal hyperextension, hyperflexion-abduction, and horizontal adduction (sustained tackling). Players returned to play on average 11 weeks after injury. Knowledge regarding mechanisms of injury, player profile, and return-to-sport timelines is important for appropriate medical management and provides potential areas to target for prevention of PM injuries.

Very-high-frequency probes for atomic force microscopy with silicon optomechanics

Atomic force microscopy (AFM) has been consistently supporting nanosciences and nanotechnologies for over 30 years and is used in many fields from condensed matter physics to biology. It enables the measurement of very weak forces at the nanoscale, thus elucidating the interactions at play in fundamental processes. Here, we leverage the combined benefits of micro/nanoelectromechanical systems and cavity optomechanics to fabricate a sensor for dynamic mode AFM at a frequency above 100 MHz. This frequency is two decades above the fastest commercial AFM probes, suggesting an opportunity for measuring forces at timescales unexplored thus far. The fabrication is achieved using very-large-scale integration technologies derived from photonic silicon circuits. The probe's optomechanical ring cavity is coupled to a 1.55 μm laser light and features a 130 MHz mechanical resonance mode with a quality factor of 900 in air. A limit of detection in the displacement of 3 × 10^-16 m/√Hz is obtained, enabling the detection of the Brownian motion of the probe and paving the way for force sensing experiments in the dynamic mode with a working vibration amplitude in the picometer range. When inserted in a custom AFM instrument embodiment, this optomechanical sensor demonstrates the capacity to perform force-distance measurements and to maintain a constant interaction strength between the tip and sample, an essential requirement for AFM applications. Experiments indeed show a stable closed-loop operation with a setpoint of 4 nN/nm for an unprecedented subpicometer vibration amplitude, where the tip-sample interaction is mediated by a stretched water meniscus.

Temperature management potentially affects carbon mineralization capacity and microbial community composition of a shallow aquifer

High-temperature aquifer thermal energy storage (HT-ATES) is a promising technique to reduce the CO2 footprint of heat supply in the frame of transitioning to renewable energies. However, HT-ATES causes temperature fluctuations in groundwater ecosystems potentially affecting important microbial-mediated ecosystem services. Hence, assessing the impact of increasing temperatures on the structure and functioning of aquifer microbiomes is crucial to evaluate potential environmental risks associated with HT-ATES. In this study, we investigated the effects of temperature variations (12-80°C) on microbial communities and their capacity to mineralize acetate in aerobically incubated sediment sampled from a pristine aquifer. Compared to natural conditions (12°C), increased acetate mineralization rates were observed at 25°C, 37°C and 45°C, whereas mineralization was decelerated at 60°C and absent at 80°C. Sequencing of 16S rRNA genes revealed that the bacterial diversity in acetate-amended and non-acetate-amended sediments decreased with rising temperatures. Distinct communities dominated by bacterial groups affiliated with meso- and thermophilic bacteria established at 45°C and 60°C, respectively, while the number of archaeal phylotypes decreased. The changes in microbial diversity observed at 45°C and 60°C indicate a potential loss of ecosystem functioning, functional redundancy and resilience, while heat storage at 80°C bears the risk of ecological collapse.

CD71 surface analysis of T cells: a simple alternative for extracorporeal photopheresis quality control

BACKGROUND

Extracorporeal photopheresis (ECP) is a leukapheresis-based cellular therapy that is used with increasing frequency worldwide to treat various T-cell-mediated diseases. Currently, the inhibition of T-cell proliferation after photopheresis is analysed frequently using time-consuming assays including radioactive thymidine assays or carboxyfluorescein succinimidyl ester (CFSE) staining. We investigated whether simple surface T-cell staining using surrogate markers of T-cell proliferation can replace time-consuming measurement of T-cell proliferation in ECP quality control.

STUDY DESIGN AND METHODS

T-cell activation markers were investigated by flow cytometry after ECP. Candidates were validated by direct comparison with the classical CFSE T-cell proliferation inhibition test and apoptosis staining. Finally, surface T-cell staining was performed in patient samples in comparison with classical methods.

RESULTS

CD71 expression exhibited the fastest and most robust upregulation, which was detectable as early as 6-8 h after T-cell stimulation and almost completely abrogated by ECP. In a direct comparison with the CFSE T-cell proliferation assay, suppression of CD71 expression after ECP was almost identical and detectable as early as 16 h after stimulation in peripheral blood mononuclear cells of healthy donors. Furthermore, in direct comparison with classical apoptosis staining, the inhibition delta of CD71 after ECP was significantly higher. Moreover, in patients under T-cell suppressive therapy, T-cell-dependent CFSE and CD71 assays exhibited decreased sensitivity to detect ECP treatment and were inferior in comparison to apoptosis staining.

CONCLUSION

Surface CD71 analysis represents a very simple quality control alternative to detect ECP-mediated T-cell proliferation inhibition in normal PBMC samples devoid of T-cell suppressive drugs.

Ramsey Interferences and Spin Echoes from Electron Spins Inside a Levitating Macroscopic Particle

We report on observations of Ramsey interferences and spin echoes from electron spins inside a levitating macroscopic particle. The experiment is realized using nitrogen-vacancy (NV) centers hosted in a micron-sized diamond stored in a Paul trap both under atmospheric conditions and under vacuum. Spin echoes are used to show that the Paul trap preserves the coherence time of the embedded electron spins for more than microseconds. Conversely, the NV spin is employed to demonstrate high angular stability of the diamond even under vacuum. These results are significant steps towards strong coupling of NV spins to the rotational mode of levitating diamonds.

Tryptorubin A: A Polycyclic Peptide from a Fungus-Derived Streptomycete

Fungus-growing ants engage in complex symbiotic relationships with their fungal crop, specialized fungal pathogens, and bacteria that provide chemical defenses. In an effort to understand the evolutionary origins of this multilateral system, we investigated bacteria isolated from fungi. One bacterial strain (Streptomyces sp. CLI2509) from the bracket fungus Hymenochaete rubiginosa, produced an unusual peptide, tryptorubin A, which contains heteroaromatic links between side chains that give it a rigid polycyclic globular structure. The three-dimensional structure was determined by NMR and MS, including a ¹³C-¹³C COSY of isotopically enriched material, degradation, derivatives, and computer modeling. Whole genome sequencing identified a likely pair of biosynthetic genes responsible for tryptorubin A’s linear hexapeptide backbone. The genome also revealed the close relationship between CLI2509 and Streptomyces sp. SPB78, which was previously implicated in an insect–bacterium symbiosis.

[Bariatric surgery: what is the ideal length of the preoperative track?]

Bariatric surgery not only has significant somatic implications but also imposes substantial behavioural and psychological changes. It is therefore essential to check previously that the potential candidate has not psychosomatic contraindications and its psychoocial context to allow adaptation to the changes requested by the intervention. After this preliminary phase the multidisciplinary support must provide a complete and adequate preparation for potential intervention, and ensure a follow-up to life in these patients. Bariatric support is therefore an ongoing process, which involves, in the preoperative phase, three steps: (1) to inform, (2) to assess and (3) prepare candidates.

Writing a coding success story: best practices and beyond. Panel discussion

What are the cornerstones of a thriving coding department? How can you ensure your coding team is built on a foundation of education, compliance, and satisfaction? We spoke with several coding managers to collect solutions and guidance for common coding challenges.

Individual hardiness and staff satisfaction

The purpose of this article is to review the literature regarding job satisfaction and how it relates to an individual's characteristics. Nurses experience a complex interplay among stressors and mediating variables. How these variables and stressors interact differently among individuals is described.

The epidemiology of trachoma in rural Kenya. Variation in prevalence with lifestyle and environment. Study Survey Group

PURPOSE

Ocular examination surveys were carried out in Kenya by the International Eye Foundation as a component of the Kenya Rural Blindness Prevention Project to determine the national prevalence of blindness and ocular morbidity and major causes. A goal of the surveys was to determine the overall geographic distribution and severity of trachoma throughout Kenya.

METHODS

Using a random cluster household sampling technique, 13,803 people of all ages and of diverse cultural and ethnic backgrounds were identified in eight regions of Kenya. A detailed examination for active and inactive trachoma was carried out on each person surveyed as part of the general ocular examination.

RESULTS

The prevalence rate of visual loss (< 20/60) due to trachoma in the better eye was 7.2/1000. Active trachoma was present in 19% of all persons examined, and 50% of all those with trachoma were found to have moderate to severe inflammation. Prevalence varied according to survey region from less than 1% in four regions where agriculture is the economic base, to 57% and 63% in two arid pastoral regions. Trachoma prevalence varied from 28% in children younger than 3 years of age to 11% in persons older than 60 years of age. Potentially blinding eyelid deformities secondary to chronic trachoma occurred in 5.0% of the rural population, and 1.2% of the rural population displayed associated corneal scarring. Lid scarring, corneal scarring, and lid deformities were greater in prevalence among females of all age groups when compared with males.

CONCLUSIONS

Trachoma prevalence in Kenya varies widely from region to region. High prevalence is associated with high climatic aridity, and lower prevalence is associated with areas of greater rainfall, sustainable agriculture, and a higher general standard of living. Within high-risk regions, there are wide variations in age-specific prevalence and severity of the disease. Potentially blinding sequelae of trachoma are more prevalent in females than in males.

Eye care delivery in developing nations: paradigms, paradoxes, and progress

Only 5% of the world's population is found in the United States, yet we as a nation consume 40% of the world's resources. In stark contrast, two thirds of the world's population live in developing countries where 90% of all blindness occurs and where even the most basic resources for eye care delivery are scarce or absent. Using U.S. criteria defining blindness (less than 20/200 [6/60]), the World Health Organization estimated in 1984 that 42-52 million people were blind from all causes, an increase of more than 10% since 1978. High population growth rates in most developing countries coupled with the failure of governments to develop health services commensurate with needs are responsible for this trend. On economic grounds alone, the U.S. eye care delivery paradigm cannot be broadly replicated in the developing world. Instead, cost-effective creative strategies, many already in place, such as mass surgery camps in Asia and delivery of eye care by non-ophthalmologists in Africa, can be expanded and streamlined. The upgrading of sight restoration and preservation care depends upon mobilization of political will within the international health community; governments must prioritize eye care as a public health problem; health planners must mobilize financial resources and work closely with technical assistance organizations, and ministries of health must cease to emulate expensive high-technology eye care models.

Hepatocellular carcinoma metastatic to the orbit in an African patient

Primary hepatocellular carcinoma rarely metastasizes to the orbit. We report a 19-year-old black man from Zimbabwe who had hepatomegaly and an orbital mass. An orbital biopsy suggested a diagnosis of hepatocellular carcinoma. Immunohistochemical stains supported the diagnosis. To our knowledge, this is only the second reported case of hepatocellular carcinoma metastasizing to the orbit and the first such reported case from Africa.

Blindness in Africa: Zimbabwe schools for the blind survey

An ophthalmic assessment survey of 430 students in Zimbabwe's two schools for the blind was conducted in 1988. Bilateral corneal opacity was found to be responsible for 75% of all blindness among institutionalised blind students. Thirteen per cent of the study patients could gain improved vision through either ocular surgical intervention or spectacle correction. Findings in this survey are similar to those from other schools for the blind elsewhere in Africa.

Blindness and eye disease in Kenya: ocular status survey results from the Kenya Rural Blindness Prevention Project

A series of eight regional eye surveys were conducted in Kenya as part of the Kenya Rural Blindness Prevention Project. Each survey consisted of clinical examinations of about 1800 individuals selected by a random cluster sampling technique in geographically distinct and culturally homogeneous rural areas; 13,803 examinations were completed in all. Together these surveys provide the basis for national estimates of the prevalence and aetiology of visual loss and ocular pathology. The results showed that 0.7% of rural Kenyans are blind in the better eye by WHO standards, and another 2.5% suffer significant visual impairment. Rates of visual loss tend to increase five-fold in each 20-year age cohort. Females have higher prevalence of visual loss than males over age 20, and certain geographical areas have markedly higher rates. The commonest cause of both blindness and visual impairment is cataract, accounting for 38% of all visual loss. Trachoma (a localised problem), glaucoma, macular degeneration, and severe refractive errors follow cataract as leading causes of blindness in the better eye. Trauma, corneal scars of various causes, phthisis, and staphyloma are important causes of monocular blindness. Nutritional eye disease does not appear to be a problem of any magnitude in rural Kenya.

Intraocular lens implantation in developing countries: an ophthalmic surgical dilemma

Rapid and remarkable development of intraocular lens technology during the past 10 years has made intraocular lens (IOL) implantation the standard of practice with cataract surgery in wealthy industrialized nations. However, although visual results of IOL implantation are vastly superior to aphakic spectacle correction after cataract surgery, several factors mitigate against the widespread implantation of IOLs in most developing nations: the high cost of surgical equipment, ancillary drugs, and intraocular lenses; difficulty in postoperative follow-up of cataract surgical patients; and a dearth of surgical personnel properly trained in IOL technology in developing nations. While many of these problems could be addressed through national initiatives, a major area of concern remains that of manpower, since the number of unoperated cataract patients is immense. One strategy for alternative surgical manpower development is the training of medical assistants to perform cataract surgery, as is presently being carried out in several African nations. The question arises, however, as to whether medical assistants, as opposed to ophthalmologists, are qualified to select patients and implant IOLs.

Childhood blindness: dateline Africa

Prevalence rates of childhood blindness and infant and childhood mortality in Africa are the highest in the world. Major factors contributing to these high rates are similar for both blindness and mortality: malnutrition, measles and other acute febrile infections, malnutrition with xerophthalmia, and limited or poor access to preventive and curative health services. Because of high national growth rates, stagnant economies, and the failure of national health care systems to expand with rapidly growing populations, childhood blindness in Africa likely will remain a significant international public health problem for the foreseeable future.

The epidemiology of trachoma in southern Malawi

A population-based prevalence survey of ocular disease was conducted in the Lower Shire River Valley of Malawi in 1983. A total of 5,436 children less than 6 years of age and 1,664 persons greater than or equal to 6 years were examined. The prevalence of inflammatory trachoma peaked in the 1-2-year-old age group at 48.7% and declined rapidly with age to less than 5% by age 15. The prevalence of cicatricial trachoma was low in young children and climbed gradually with age to greater than 40% among those greater than or equal to 50 years. Risk factors for inflammatory disease in young children included low socioeconomic status of the family, long walking distance to the household's primary source of water, absence of a latrine in the family compound, and presence of trachoma among siblings. Indices of crowding practices were not associated with inflammatory disease. An apparent inverse association of facewashing and inflammatory trachoma in children did not hold up when adjusted for other risk factors.

Conjunctival melanoma in Africa

Malignant melanoma of the eye and adnexa is rare in blacks. A highly unusual malignant melanoma of the tarsal conjunctiva in an adult Ethiopian female, believed to be the first reported in a black patient, is described. Factors that contribute to melanoma in blacks and rates of occurrence are reviewed and discussed.

Trachoma grading: observer trials conducted in southern Malawi

A variety of grading schemes have been proposed for the clinical classification of inflammatory trachoma. During a population based study of ocular disease conducted in southern Malawi we tested a simplified version of the current WHO grading scheme. Intraobserver agreement statistics were less than satisfactory for three of four graders. Interobserver agreement when compared against either a well experienced standard ophthalmologist or a consensus grade improved over time for two of the three graders. However, initial agreement for all three graders was only fair to moderate. Previous studies of trachoma grading schemes support these unsatisfactory results. A new system of classification is needed that is both accurate and reliable in a field setting.

Cost-effective cataract surgery in developing nations

Today approximately twenty million people are blind (visual acuity less than 3/60 [10/200]) and tens of millions more are visually disabled (visual acuity less than 6/18 [6/60]) from cataract. Most of these people live in impoverished developing nations. The logistics of providing cataract surgical care for them are complex. Simplifying the cataract operation, employing appropriate technology, and training non-physicians in intraocular surgery is efficient cost-effective strategy in many developing African nations.

Portable battery-powered indirect ophthalmoscope for field surveys

Portable indirect ophthalmoscopy is a useful adjunct to field surveys and rural eye care in developing nations. The method for converting an electrically-powered indirect ophthalmoscope to a portable battery-powered unit is described.

Limbal vernal keratoconjunctivitis with a hypertrophic limbal mass lesion

A case of limbal vernal keratoconjunctivitis associated with a hypertrophic mass lesion measuring 8 X 5 X 3 mm is reported. The histopathology of this mass, which consisted of hyperplastic epithelium with eosinophilic infiltration and thickened subepithelial stroma of irregular hyperplastic collagenous connective tissue interspersed with numerous eosinophils and inflammatory cells, is presented. A large limbal-mass lesion such as this has not been previously described in association with limbal vernal keratoconjunctivitis.

Prevalence and severity of xerophthalmia in southern Malawi

The first population-based study of xerophthalmia in Africa was conducted in the Lower Shire River Valley of Malawi in the autumn of 1983. A total of 5,436 children under six years of age were examined by three survey teams over an eight-week period. The prevalence of active xerophthalmia was 3.9%. Rates for night blindness and active corneal disease were more than five times the World Health Organization criterion for a problem of public health importance. Xerophthalmic corneal scarring occurred at a rate of 5.9/1,000, more than 10 times the World Health Organization criterion. All cases of bilateral blindness in this age group were considered to be due to vitamin A deficiency. Given recent evidence from Asia linking even subclinical vitamin A deficiency to increased risk of mortality and morbidity, this disease is not only a leading cause of blindness in this area, but may have an important impact on child survival as well.

Blindness and visual impairment in southern Malawi

There is a paucity of reliable information on the prevalence and causes of blindness in sub-Saharan Africa, and this produces problems in designing and evaluating blindness prevention programmes. To address this problem and to provide baseline data for the evaluation of such programmes, the government of Malawi, in conjunction with a number of agencies, conducted a population-based prevalence survey of ocular disease in the Lower Shire River Valley in southern Malawi, an area where blindness is common. The prevalence of bilateral blindness found (1.27%) is similar to that in other developing countries and represents a significant public health problem. At least 60% of this blindness is preventable or easily reversible.

Destructive epidemic Neisseria gonorrheae keratoconjunctivitis in African adults

An epidemic of Neisseria gonorrheae keratoconjunctivitis in African adults occurred in Malawi in 1983. Sixteen patients, seven females and nine males, aged 18 to 60 years, were admitted to the inpatient ocular services at Queen Elizabeth Central Hospital in Blantyre from 1 February to 28 May 1983, all with severe bilateral purulent keratoconjunctivitis and concomitant venereal infection secondary to N. gonorrheae. Corneal melting, corneal perforation with iris prolapse, and endophthalmitis occurred in 10 eyes, of which five required enucleation. Thirteen additional eyes sustained severe visual loss secondary to corneal ulceration, leucomata, and healed corneal perforation. The route of transmission and factors of epidemicity are speculative. Because of worldwide epidemic venereal infection ophthalmologists and epidemiologists should be alert to probable sporadic N. gonorrheae epidemics in adults. Such outbreaks could occur elsewhere, especially in the developing world, and ocular gonococcal infection might become a significant cause of irreversible blindness.

Cataract and corneal opacity are the main causes of blindness in the Samburu tribe of Kenya

An ocular status survey of the Samburu tribe of Kenya was carried out. There were 844 survey members in an age and sex stratified cluster sample. The prevalence of those who were found to have moderate visual loss or worse (less than 20/60 [6/18] in the better eye) was 3.8%. Those blind by USA criteria represented 1.7% of the total population. The two principal causes of blindness, cataract and corneal opacity, are both surgically amenable. A description of the Samburu people, the survey methods, and a summary of the survey findings are included.

Surgical treatment of open angle glaucoma is preferable to medical management in Africa

Primary open angle glaucoma is the third leading cause of blindness in Africa, causing roughly 16% of all blindness and thereby involving approx. 800,000 people on the continent. The overall prevalence and age-group breakdown of the disease is similar to that in industrialized countries, involving almost exclusively people over 40, and rising steadily thereafter with age. Factors such as a generally asymptomatic disease, definitely symptomatic medical treatment, the high cost of drugs and their irregular availability, difficulties in obtaining adequate long term chronic follow-up, and poor patient understanding of the disease all combine to make medical therapy of this condition unacceptable in Africa. Modern surgical techniques are safe, effective, and comparatively cost effective in the treatment of glaucoma. Early surgery is therefore recommended whenever possible.

Visual disability and blindness secondary to refractive errors in Africa

Optical defects of the light-focusing apparatus of the eye are called errors of refraction. They are responsible for 13% of all significant vision loss in Kenya, ranking third of all causes, after cataract and trachoma. As the overall prevalence of such visual impairment in the Country is 3.7%, roughly 0.5% of the population can be said to need spectacles to obtain normal vision. The comparable figure for secondary school children in Nigeria has been found to be 2.4%. In addition, patients require special spectacles after cataract surgery to obtain adequate vision; without such spectacles these patients are still 'blind' by World Health Organization criteria. These glasses can be obtained through mission societies and various charitable organizations for a little as $5 per pair, and can be manufactured locally with available ophthalmic manpower and technology. Alternatives to spectacles such as contact lenses, intra-ocular lenses and Kerato-refractive surgery are not suitable for use in developing Countries.

Field methodology for ocular surveys in rural Africa

A series of nine on-site ocular surveys has been carried out in rural Kenya. This article summarizes the organizational and logistical experiences of these site surveys.