Antemortem vitreous potassium may strengthen postmortem interval estimates.

The purpose of this letter is to highlight that postmortem interval estimates using vitreous potassium concentrations may be further optimised by calibration against antemortem vitreous samples.

Biochemical analysis of the living human vitreous.

BACKGROUND: To date, our understanding of the biochemical composition of the living human vitreous relies on extrapolations from animal or human post-mortem studies. METHODS: This was a cross-sectional study of vitreous samples from 27 individuals scheduled for retinal surgery within a tertiary hospital. From each vitreous sample, the concentrations of sodium, potassium, chloride, calcium, magnesium, glucose, lactate, ß- hydroxybutyrate, copper, zinc, selenium, iron, ferritin and transferrin and osmolality were measured. Perioperative serum samples were also obtained for comparison. RESULTS: The following vitreous mean ± standard deviation (95% confidence interval of the mean) was observed for each analyte: sodium, 146.7 ± 3.3 (145.4-148.0) mmol/L; potassium, 5.73 ± 0.86 (5.39-6.08) mmol/L; chloride, 121.6 ± 2.6 (120.6-122.7) mmol/L; calcium, 1.128 ± 0.518 (0.923-1.333) mmol/L; magnesium, 0.900 ± 0.158 (0.838-0.962) mmol/L; glucose, 2.97 ± 0.98 (2.58-3.36) mmol/L; lactate, 3.97 ± 1.09 (3.54-4.40) mmol/L; osmolality, 289.5 ± 6.9 (286.6-292.5) mOsm/kg; BOHB, 0.0937 ± 0.0472 (0.0750-0.1124) mmol/L; copper, 0.519 ± 0.269 (0.412-0.625) µmol/L; zinc, 1.95 ± 1.09 (1.52-2.38) µmol/L; selenium, 0.1035 ± 0.0276 (0.0923-0.1146) µmol/L; iron, 3.11 ± 1.40 (2.56-3.66) µmol/L; ferritin, 19.5 ± 10.3 (15.5-23.6) µg/L; transferrin, 0.0878 ± 0.0526 (0.0670-0.1086) g/L. Vitreous biochemistry was not significantly different between male and female participants. Vitreous biochemistry was significantly different between non-diabetic and diabetic participants. Vitreous biochemistry was significantly different from the vitreous substitute BSS Plus (Alcon, USA). The vitreous extracted from living humans was markedly different from the commonly reported reference values obtained from animal studies. CONCLUSIONS: The current data provide hitherto unavailable information about the biochemical composition of the living human vitreous.

Pilot randomized trial of a nanopulse retinal laser versus conventional photocoagulation for the treatment of diabetic macular oedema.

BACKGROUND: To assess the efficacy of a new nanopulse laser, retinal regeneration therapy for the treatment of diabetic macular oedema. DESIGN: Randomized, non-inferiority, trial. PARTICIPANTS: 20 eyes of 17 subjects in the retinal regeneration therapy group and 18 eyes of 14 subjects in the conventional group were analysed. METHODS: The treatment group received retinal regeneration therapy laser, and the control group received photocoagulation. MAIN OUTCOME MEASURES: The primary outcome was the optical coherence tomography-measured change in central retinal thickness at 6 months. A secondary outcome was the change in logarithm of minimum angle of resolution visual acuity at 6 months. Non-inferiority required the one-sided 95% confidence interval of the mean retinal thickness reduction after retinal regeneration therapy to be within 35 µm of the reduction after control laser. RESULTS: When outliers were included in the dataset, the difference in retinal thickness reduction by analysis of covariance was 10.9 (standard deviation 17.6) mm in favour of the control laser. The difference between groups in retinal thickness reduction was 40.8 mm. If two extreme outliers were excluded, the difference was 5.6 (standard deviation 14.2) mm in favour of the retinal regeneration therapy laser, and the D optical coherence tomography was 18.5 mm. The visual acuity difference between groups was 0.059, meeting non-inferiority requirements. CONCLUSIONS: Although retinal thickness reduction was not unambiguously non-inferior, in the short-term, retinal regeneration therapy approximates the clinical efficacy of conventional photocoagulation, stabilizing visual acuity and providing motivation for larger trials assessing retinal regeneration therapy.

Killing two birds with one stone: the potential effect of cataract surgery on the incidence of primary angle-closure glaucoma in a high-risk population.

BACKGROUND: To estimate the proportion of cataract surgery performed at various visual acuity and lens opacity thresholds that would coincidentally treat early angle-closure disease, and to estimate the effect of this surgery on the incidence of primary angle-closure glaucoma. DESIGN: Cross-sectional, population-based survey in Meiktila, Myanmar. PARTICIPANTS: Total of 2076 inhabitants, 40 years of age and over were included. METHODS: Eyes with cataract-induced visual impairment, and primary angle-closure disease were identified. Analyses were stratified by various pinhole-corrected visual acuity and Lens Opacity Classification System III scores thresholds. MAIN OUTCOME MEASURES: The dual role of cataract surgery in primary cataract treatment and primary angle-closure glaucoma prevention was estimated. RESULTS: Of 4153 eyes available for analysis, 261 eyes were either primary angle-closure suspect or primary angle closure; 975 eyes had a visual acuity of <6/18 and Lens Opacity Classification System III score ≥ 3 on the nuclear or cortical scales. Of these, 86 eyes had either primary angle-closure suspect or primary angle closure. If cataract surgery were performed on all 975 eyes, this would potentially prevent up to 86 cases of primary angle-closure glaucoma in this population; 8.82% (95% confidence interval 7.12-10.78%) of the cataract surgery would address the cataract and prevent primary angle-closure glaucoma. This would achieve a 38.46% (95% confidence interval 20.23-59.43%) relative reduction in the incidence of primary angle-closure glaucoma in the adult population. CONCLUSION: In populations with a high prevalence of both visually significant cataract and angle-closure disease, quality cataract extraction can serve a dual role of visual restoration and reducing the incidence of angle-closure disease in the population: killing two birds with one stone.

Sutureless vitrectomy.

Sutureless vitrectomy has rapidly been accepted as an essential part of a vitreoretinal surgical setup. The size and structure of the wound along with near intact conjunctival covering makes the incision self-sealing and safe. This allows the vitrectomy instruments to be used without creating an initial limited peritomy to expose bare sclera, and obviates the need for sutures at the end of the procedure. Wound construction is the essential step in ensuring postoperative wound stability. Both one-step and two-step wound constructions have been described. Key points include an oblique, tunneled approach to ensure a valve-like effect as well as misalignment of conjunctival and scleral wounds by displacing conjunctiva during construction. Advantages include decreased operative times in certain cases and decreased postoperative inflammation, early postoperative rehabilitation, improved patient comfort, and minimal conjunctival damage. Complications are based around wound competence, hypotony, and its relationship to endophthalmitis rates. Early reports highlighted an increase in endophthalmitis though further studies are required to accurately assess the incidence. Endophthalmitis has not been reported in cases that underwent fluid/air exchange. This review focuses on techniques, benefits, complications, personal experiences, and the safety profiles of sutureless vitrectomy systems. A literature review was undertaken using 'Medline' and 'Pubmed'. Search terms included sutureless vitrectomy, 20 gauge, 23 gauge, 25 gauge, and transconjunctival and small gauge vitrectomy.

Cataract surgical coverage and self-reported barriers to cataract surgery in a rural Myanmar population.

PURPOSE: The aim of this study is to determine the cataract surgical coverage and investigate the barriers to cataract surgery as reported by those with cataract-induced visual impairment in rural Myanmar. METHODS: A cross-sectional, population-based survey of inhabitants 40 years of age and over from villages in the Meiktila District (central Myanmar); 2481 eligible participants were identified and 2076 participated. Data recording included corrected visual acuity, dilated slit lamp examination and stereoscopic fundus examination. Lens opacity was graded using the Lens Opacities Classification System III. Participants with cataract-induced visual impairment (acuity < 6/18 in better eye) were also invited to respond to a verbal questionnaire about barriers to cataract surgery. RESULTS: Cataract surgical coverage for visual acuity cut-offs of <6/18, <6/60 and <3/60 was 9.74%, 20.11% and 22.3%, respectively, for people and 4.18%, 9.39% and 13.47%, respectively, for eyes. Cataract surgical coverage was higher for men than women, but gender was not associated with refusal of services. Of the 239 who responded to the extra questionnaire, 216 were blind or had low vision owing to cataract. Three quarters refused referral for surgery: cost and fear of surgery were the most frequently reported barriers. CONCLUSION: Cost plays a large role in the burden of cataract in this region. Implementation of educational programmes, reforms to local health service and subsidization of ophthalmic care may improve the uptake of cataract surgery.

Corneal thickness and intraocular pressure in a nonglaucomatous Burmese population: the Meiktila Eye Study.

OBJECTIVE: To determine correlates of central corneal thickness (CCT) and its relationship to intraocular pressure (IOP) in a Burmese population. METHODS: We performed a population-based survey of inhabitants 40 years or older in Myanmar; of 2076 participants, data from 1909 nonglaucomatous subjects who underwent ultrasound pachymetry and Goldmann applanation tonometry were analyzed. Linear mixed effects models adjusting for nonindependence of right and left eye data were constructed. RESULTS: Mean (SD) CCT was 521.9 (33.3) microm, and the mean (SD) IOP was 14.5 (3.4) mm Hg. Intraocular pressure and spherical equivalent were significant predictors of CCT (P < .001 and P = .01, respectively). Age, sex, body mass index, and corneal curvature were not significant predictors. Central corneal thickness was the only significant predictor of IOP (ie, an increase of 100 microm in CCT predicted an increase of 1.3 mm Hg in IOP). The Spearman correlation between CCT and IOP for the right and left eyes was highly significant (P < .001), but the Spearman rank correlation values (R(2) = 0.016 and R(2) = 0.017, respectively) were weak. CONCLUSIONS: The CCT in this Burmese population was significantly associated with IOP and spherical equivalent. The weak association between CCT and IOP is consistent with that of other population-based studies. Other corneal factors are likely to influence Goldmann applanation tonometry.

Awareness of diabetic eye disease among general practitioners and diabetic patients in Yangon, Myanmar.

BACKGROUND: Diabetes is an increasing problem in Myanmar with more than three million people affected. There are no data on awareness of diabetic retinopathy among the general practitioners (GPs) or diabetic population of Myanmar. This study aims to evaluate the awareness of diabetes-related eye disease among GPs and diabetic patients in Yangon, Myanmar. DESIGN: A cross-sectional survey. METHODS: From the Myanmar Medical Association Registry of 978 practicing GPs in Yangon, 200 were randomly selected and a structured questionnaire was sent to each. Each GP was asked to give a separate questionnaire to the first five diabetic patients who attended their practice. RESULTS: One hundred GPs and 480 patients returned the questionnaires. Although 99% of GPs were aware that diabetes could result in loss of vision, 49% never examined the fundi of their diabetic patients. Of the diabetic patients, 86% were aware that diabetes could damage their eyesight. Although 92% realized they should visit an ophthalmologist regularly, only 57% had seen an ophthalmologist. Patients who never attended school were less likely to visit an ophthalmologist than those with tertiary education (odds ratio 0.24; 95% confidence interval 0.09, 0.66). Patients with diabetes for less than 2 years were less likely to visit an ophthalmologist than those with diabetes for more than 10 years (odds ratio 0.21; 95% confidence interval 0.9, 0.44). There was no association between age, gender or work status and the likelihood of having seen an ophthalmologist. CONCLUSION: Although both GPs and diabetic patients are aware of the need for regular fundal screening, just over half the patients had been screened. There exists a need for programmes in Myanmar to induce a behavioural change in diabetic patients with regards to screening examinations.

Central corneal thickness among Aboriginal people attending eye clinics in remote South Australia.

PURPOSE: To determine the central corneal thickness (CCT) and its demographic associations among Aboriginal people attending eye clinics in remote South Australia. METHODS: A clinic-based cross-sectional study was conducted involving opportunistic sampling of patients. Eligible participants underwent measurement of CCT by ultrasound pachymetry. The results were compared with a group of Caucasian control patients. RESULTS: All patients (189) who were invited to participate in the study had their CCT measured. The mean age was 44.8 +/- 14.5 years, and women comprised 57.7% of the sample. The control group consisted of 115 Caucasian participants. The mean age was 47.1 +/- 14.8 years, and women accounted for 55.7% of the sample. Mean CCT for Aboriginal participants was 514.9 +/- 30.5 microm in the right eye and 515.6 +/- 30.5 microm in the left eye (t = 1.1, P = 0.3). Mean right CCT for Caucasian participants was 544.6 +/- 31.9 microm and mean left CCT in this group was 547.1 +/- 32.2 microm (t = 4.6, P < 0.001). There was a significant difference between the right (t = 8.4, P < 0.001) and left (t = 8.8, P < 0.001) CCT of Aboriginal and Caucasian participants. CONCLUSIONS: The CCT among Aboriginal patients attending eye clinic in remote South Australia was significantly thinner than that of a Caucasian control group. Thinner corneas among this group of Aboriginal patients may indicate a need to adjust intraocular pressure according to CCT and to be more vigilant for glaucoma.

Risk factors for primary open-angle glaucoma in a Burmese population: the Meiktila Eye Study.

PURPOSE: To report the risk factors associated with primary open-angle glaucoma (POAG) in the Burmese population. METHODS: The Meiktila Eye study, a population-based cross-sectional study, included inhabitants 40 years of age and over from villages in the Meiktila District. Of 2481 eligible participants identified, 2076 participated in the study and sufficient examination data to diagnose glaucoma in at least one eye was obtained in 1997 participants. The ophthalmic examination included slit-lamp examination, tonometry, gonioscopy and dilated stereoscopic fundus examination. Definitions adhered to the International Society for Geographic and Epidemiological Ophthalmology's recommendations. Univariate and multivariate analyses of potential risk factors were performed. RESULTS: The overall prevalence of POAG was 2.0% (95% CI 0.9-3.1). In the univariate analysis, increasing age (P = 0.024), spherical equivalent (P = 0.01), axial length (P = 0.023) and intraocular pressure (IOP; P < 0.001) were significantly associated with POAG. And in the multivariate analysis, myopia <0.5 D (P = 0.049), increasing age and IOP (P < 0.001) were significant risk factors for POAG. CONCLUSION: POAG in this Burmese population was associated with increasing age, axial myopia and IOP.

Distance refractive error among Aboriginal people attending eye clinics in remote South Australia.

PURPOSE: To determine the prevalence of distance refractive error among Aboriginal people attending eye clinics in remote South Australia. METHODS: A clinic-based cross-sectional study was conducted that involved opportunistic sampling of Aboriginal people attending eye clinics in remote South Australia. There were 189 individuals who were invited to participate in the study all of whom underwent ophthalmic examination. This examination included measurement of pinhole-corrected visual acuity and non-cycloplegic autorefraction. RESULTS: Automated refractive error examinations were performed on 148 people within this sample. The mean age was 44.8 +/- 14.5 years and women comprised 57.7% of the sample. The overall mean refractive error was -0.01 +/- 1.8 D (SD). The prevalence of myopia (spherical equivalent (SE) < -0.5 D), high myopia (SE less than or equal to -6.0 D), hypermetropia (SE > 0.5 D), astigmatism (cylinder at least -0.5 D) and anisometropia (difference in SE of >0.5 D) was 31.1%, 0.7%, 33.1%, 55.8% and 45.9%, respectively. Further analyses revealed significant age-related trends with both myopia and hypermetropia. There were no gender associations with any form of refractive error. Of those people with clinically significant refractive error, 51/148 (34%), only four people owned distance spectacles. CONCLUSIONS: There continues to be a level of uncorrected distance refractive error within these patients. This represents a need to screen for refractive error among Aboriginal people in remote locations and to provide them with appropriate spectacle correction.

Prevalence of trachoma-related trichiasis and corneal opacity in rural Myanmar: the Meiktila Eye Study.

OBJECTIVE: To describe the prevalence of trachomatous trichiasis and corneal opacity (CO) within central Myanmar. DESIGN: Population-based cross-sectional ophthalmic survey. PARTICIPANTS: Random, stratified, cluster sampling of the inhabitants > or =40 years of age from villages in the Meiktila District was performed; 2481 eligible participants were identified and 2076 participated in the study. METHODS: Visual acuity was measured using an E Snellen chart at 6 meters. Lid, ocular surface, and anterior segment examinations were performed at the slit lamp. MAIN OUTCOME MEASURES: Trachoma was graded as trachomatous trichiasis (TT) or CO according to the World Health Organization grading system. RESULTS: The population prevalence of trachoma (TT and CO) was 2.6% (95% confidence interval [CI]. 1.67%-3.42%). For every 1-year increase in age, the odds of trachoma increased by 5.3% (95% CI, 4.9%-5.7%). There was no significant effect of gender on the prevalence of trachoma (P = 0.5). No formal schooling was a strong predictor of trachoma (odds ratio, [OR], 4.9; 95% CI, 3.9-6.1), and having <3 children in the house was protective (OR, 0.75; 95% CI, 0.61-0.93); however, neither occupation nor the number of people in a household had an effect on trachoma. CONCLUSIONS: The prevalence of blinding trachoma in central Myanmar remains relatively low. This is a tribute to the success of the Burma Trachoma Control Program and demonstrates the need for such a program to remain an integral part of public health care and community health services to further diminish the prevalence of this condition. This will be facilitated by a focus on trachoma risk factors and further research into the prevalence of inflammatory trachoma within the pediatric population.

Association between stature, ocular biometry and refraction in an adult population in rural Myanmar: the Meiktila eye study.

PURPOSE: To study the association between adult stature and ocular biometric parameters and refraction. METHODS: In a population-based cross-sectional ophthalmic survey of 2418 adults (> or = 40 years old) living in the rural villages in central Myanmar, height and weight were measured using a standardized protocol, and body mass index was calculated. Non-cycloplegic refraction and corneal curvature were determined by an autorefractor. Ultrasound pachymetry was performed and ocular biometry, including axial length, anterior chamber depth, lens thickness and vitreous chamber length were measured using A-mode ocular ultrasonography. RESULTS: Height and weight were significantly correlated with age, gender and all the ocular biometric parameters, except lens thickness. After adjusting for age and gender, taller and heavier persons had eyes with longer axial length, deeper anterior and vitreous chambers, and flatter and thicker corneas than shorter persons. Height was not significantly correlated with refraction, and heavier persons tended to be less myopic (P < 0.001). Multivariate linear regression models revealed consistent results with the findings for association between height, weight and ocular biometry and refractive error. CONCLUSIONS: Adult stature is independently associated with vitreous chamber length and corneal radius in this Burmese population. Heavier persons were slightly hyperopic.

Atrial fibrillation following subconjunctival injection of mydricaine number 02.

Mydricaine is a mydriatic agent used as a subconjunctival injection to maintain perioperative mydriasis. The drug consists of a mixture of 1.3 mg atropine sulphate, 0.12 mg adrenaline and 8.4 mg procaine hydrochloride in a single vial of 0.4 mL. It is common practice to use mydricaine injections during vitreoretinal surgery in the Royal Adelaide Hospital. Even though the drug is used widely in many vitreoretinal centres, mydricaine is not listed in the British National Formulary nor Monthly Index of Medical Specialities. Therefore, case reports provide the main forum for reporting side-effects.

Prevalence of trachoma and diabetes-related eye disease among a cohort of adult Aboriginal patients screened over the period 1999-2004 in remote South Australia.

BACKGROUND: To determine the prevalence of trachoma and diabetes-related eye disease within the adult Aboriginal population screened by the South Australian Eye Health Program between 1999 and 2004 inclusive. METHODS: The South Australian Eye Health Program visited 22 Aboriginal communities in remote South Australia. Visiting ophthalmologists and optometrists systematically collected data on the cohort of adult patients seen over the period 1999-2004. Prevalence and grade of trachoma according to World Health Organization classification and the prevalence and degree of diabetic retinopathy according to the Early Treatment Diabetic Retinopathy Study and National Health and Medical Research Council guidelines were recorded. RESULTS: A population of 1651 Aboriginal patients was examined. Sixty-two per cent were female and 38% were male. Twenty patients (1.2%) had evidence of active trachoma with 260 (15.7%) patients having either lid scarring, trichiasis or corneal opacity. There was no significant association between gender and the prevalence of trachoma (P = 0.48). Seven hundred and seventy-one patients within the examined population had diabetes mellitus (46.70%). Significantly more women than men were affected and prevalence increased with age (P < 0.0001). One hundred and sixty-nine patients (22%) with diabetes mellitus had features of diabetic retinopathy, and of these patients 77 had background diabetic retinopathy (46%) and 92 (54%) had either proliferative diabetic retinopathy or maculopathy. Prevalence of clinically significant macula oedema among those with maculopathy (14 of 50 patients) was 28%. CONCLUSIONS: The data suggest that although trachoma is still endemic in this South Australian Aboriginal population the prevalence and severity are less than previously reported. Diabetes mellitus has a high prevalence within this population and great potential for detrimental visual sequelae.

Four-year review of open eye injuries at the Royal Adelaide Hospital.

PURPOSE: To review the epidemiology of penetrating eye injuries and ruptured globes presenting to the Royal Adelaide Hospital, South Australia. METHODS: A retrospective case review over a 4-year period. RESULTS: There were 109 penetrated or ruptured globes in 105 patients. The average age was 41 years and 80.2% were men. Over half were from rural areas. The commonest cause of injury was hammering metal followed by motor vehicle accidents. Falls in the elderly were the commenest cause of globe ruptures. A final visual acuity of 6/12 or better was found in 40% of eyes and no perception of light in 27%. CONCLUSIONS: At the Royal Adelaide Hospital, the predominant referral centre for serious ocular injury in South Australia, approximately 25 open globe injuries are encountered a year. Although the epidemiology of these injuries was found to be similar to those previously reported in Victoria and rural New South Wales, differences were thought to reflect to the ageing population of South Australia. Rupture of an old, healed large-incision cataract extraction wound was the commonest cause of ruptured globe. An effective preventive strategy to reduce the incidence of severe ocular trauma has yet to be implemented. The concept of a national population-based severe ocular trauma database is considered.