Associate Professor Mark Roth
BSc(Pharmacology) BAppSc(Optom) PGCertOcTher NEWENCO FAAO OAM
Consequences of declines in measles vaccinations
Even a small decrease in the measles vaccination rate could lead to a three-fold increase in cases, a study has concluded.
Researchers looked into the public health and economic impact of ‘vaccine hesitancy’, which is defined as a ‘delay or refusal to accept vaccination based on personal beliefs despite availability.’
Using Center for Disease Control data to simulate measles, mumps and rubella (MMR) vaccine coverage for US children aged from two to 11 years, researchers estimated the number of measles cases and associated costs that would occur with declining vaccine coverage due to non-medical reasons.
At baseline, MMR vaccine coverage was 93 per cent, and the prevalence of non-medical exemptions was two per cent. This would yield 48 measles cases annually in this age group across the USA. However, if vaccine coverage dropped by five per cent, the estimated number of measles cases would increase to 150, costing the public sector an additional $2.1 million.
The researchers concluded that even minor reductions in childhood vaccinations, driven by vaccine hesitancy, will have substantial public health and economic consequences. In effect, when people opt out of vaccination, they are not just making a personal choice, they are affecting their community as a whole. Because vaccine hesitant parents tend to live in clusters, it makes the potential of large outbreaks much more likely.
JAMA Paediatrics July 24, 2017. doi:10.1001/jamapediatrics.2017.1695
Vision loss in Indigenous Australians
The National Eye Health Survey has found that vision loss is 2.8 times more prevalent in Indigenous Australians than in non-Indigenous Australians.
Researchers conducted a nationwide, cross-sectional, population-based survey of Indigenous Australians aged 40 years or older and non-Indigenous Australians aged 50 years and older. Trained examiners conducted standardised eye examinations, including visual acuity, perimetry, slitlamp examination, intraocular pressure and fundus photography.
Overall, the prevalence of vision loss in Australia was 6.6 per cent: 6.5 per cent in non-Indigenous Australians and 11.2 per cent in Indigenous Australians.
In Indigenous Australians, the leading causes of vision loss were uncorrected refractive error (60.8 per cent), cataract (20.1 per cent) and diabetic retinopathy (5.2 per cent).
The study authors concluded that improvement in eye health care in Indigenous communities is required. The leading causes of vision loss —uncorrected refractive error and cataract—are readily treatable.
Ophthalmology 2017 Jul 6. doi: http://dx.doi.org/10.1016/j.ophtha.2017.06.001
Anti-VEGF for diabetic retinopathy remains a strong option
While it’s too early to suggest that health-care providers should eliminate the use of lasers for the treatment of proliferative diabetic retinopathy, recent research has shown anti-VEGF injections to be a strong option for some patients.
‘Is it time to retire your laser?’ asked Adam Glassman of the Jaeb Center for Health Research, in an editorial in JAMA Ophthalmology. ‘There are now two large, randomised clinical trials that show the benefits of anti-VEGF treatment compared with panretinal photocoagulation,’ Glassman wrote. The trials are the Diabetic Retinopathy Clinical Research Network Protocols and the CLARITY study, which reported successful outcomes with the use of anti-VEGF injections compared with panretinal photocoagulation treatment, the standard treatment for many years.
‘Anti-VEGF was a more effective treatment for preserving visual function and reducing complications that can accompany proliferative diabetic retinopathy,’ Glassman wrote. ‘Despite the promising results of the clinical trials, the barriers for wide-spread use of anti-VEGF agents persist.’
Glassman said compliance was a barrier. In the Protocol S trial, 12 per cent of participants in the anti-VEGF group failed to complete all visits through two years, and nine per cent of the aflibercept group in the CLARITY trial were also lost to follow-up. A second barrier noted by Glassman was cost, although the use of bevacizumab (Avastin) was mentioned as a cost-effective alternative.
JAMA Ophth 2017; Jul 1; doi: 10.1001/jamaophthalmol.2017.1652.
Efficacy of phacoemulsification
Phacoemulsification (phaco) as a solo procedure lowers intraocular pressure and reduces patient dependency on glaucoma medications.
Researchers conducted a retrospective review including 32 studies and 1,826 subjects with comorbid cataract and primary open angle glaucoma who underwent phaco and its effect on IOP and the required amount of topical glaucoma medications.
Researchers found a 12 per cent, 14 per cent, 15 per cent and nine per cent reduction in IOP from baseline at six, 12, 24 and 36 months, respectively, after phaco. A mean reduction in glaucoma medications of 0.57, 0.47, 0.38 and 0.16 was noted per patient at six, 12, 24 and 36 months after phaco, respectively.
The IOP-lowering effects appear to last at least 36 months, with gradual loss of the initial effect noted after two years, according to researchers.
A large variance in IOP reductions after phaco, ranging from 1.2 per cent to 29.4 per cent, was also observed. The researchers suggested that the difference may be the result of surgical variations or by differences in patient characteristics between as well as within the studies.
The review implies that if phaco can temporarily reduce the medication burden on patients, it may open a window during which there is a reduced risk of glaucoma surgical failure.
J Glaucoma 2017; 26: 6: 511–522. doi: 10.1097/IJG.0000000000000643
Disinfecting your tonometer
Sodium hypochlorite (diluted bleach) offers effective disinfection against adenovirus and herpes simplex virus (HSV) for tonometers, a report by the American Academy of Ophthalmology states.
Literature searches were conducted in the PubMed and the Cochrane Library databases for original research investigations. After exclusion criteria were applied, 10 laboratory studies remained for this review.
The infectious agents covered in the assessment were adenovirus 8 and 19, HSV 1 and 2, human immunodeficiency virus 1, hepatitis C virus, enterovirus 70, and variant Creutzfeldt-Jakob disease.
All four studies of adenovirus 8 concluded that after sodium hypochlorite disinfection, the virus was undetectable, but only two of the four studies found that 70% isopropyl alcohol (alcohol wipes or soaks) eradicated all viable viruses.
All three HSV studies concluded that both sodium hypochlorite and 70% isopropyl alcohol eliminated HSV. Ethanol, 70% isopropyl alcohol, diluted bleach and mechanical cleaning all lack the ability to remove cellular debris completely, which is necessary to prevent prion transmission.
It was also determined that disinfectants can cause tonometer tips to swell and crack by dissolving the glue that holds the hollow tip together. The cracks can irritate the cornea, harbour microbes or allow disinfectants to enter the interior of the tonometer tip.
The report recommends the use of sodium hypochlorite against adenovirus and HSV but encourages clinicians to regularly check their tonometers for signs of damage.
Ophthalmology 2017; Jul 11. doi: http://dx.doi.org/10.1016/j.ophtha.2017.05.033.
For children, low dose atropine is better than high dose
Low-dose atropine showed equal efficacy in slowing myopia progression in children and had fewer side-effects than higher doses, according to a large meta-analysis of published studies.
Researchers reviewed 720 studies that included 3,137 children younger than 18 years; 268 were Asian, 201 were Caucasian. Studies with high, moderate and low-dose atropine (0.01%) were included, and while efficacy was not dose-dependent, side-effects were shown to be positively correlated with concentration.
The pooled data showed significantly less progression of myopia with all doses of atropine compared with control groups, but no correlation was found between dose and treatment effect. Ethnicity also had no impact on the effect of treatment.
A total of 308 adverse events occurred in 2,425 patients in the atropine groups (12.7 per cent). The difference with control groups was statistically significant. The most common effects were photophobia, poor vision at near and allergy, and their incidence significantly increased with dose escalation.
The study authors recommended the use of the lowest dose of atropine (0.01%) for therapy, but called for clinical trials with that dose. However, the authors also suggested that combined approaches, including outdoor activities, orthokeratology, bifocals and possibly stem cells, might be necessary to better prevent the progression of myopia.
JAMA Ophthalmol 2017; 135: 6: 624-630. doi: 10.1001/jamaophthalmol.2017.1091.
Contact lenses risk no higher in children
The number of adverse effects in contact lens wearing patients under the age of 18 years is no higher than in adults, according to a review published in Optometry and Vision Science.
Authors of the research review collated data from a range of studies to estimate the incidence of complications in patients younger than 18 years. The analysis focused on signs of corneal infiltrative events measured against ‘patient years’ of soft contact lens wear.
In three large prospective studies representing between 159 and 723 patient years of soft contact lens wear in patients eight to 14 years, the incidence of corneal infiltrative events was low: 136 per 10,000 years.
Data from a large retrospective study showed similarly low rates of corneal infiltrative events: 97 per 10,000 years in eight- to 12-year-olds (based on 411 patient years of wear) and 335 per 10,000 years in 13- to 17-year-olds (based on 1,372 patient years of wear). None of the prospective studies reports any cases of microbial keratitis.
One retrospective study found no cases of microbial keratitis occurred in eight- to 12-year-olds (411 patient years) and an incidence of 15 per 10,000 patient years in 13- to 17-year-olds (1,372 patient years), which is no higher than the incidence of microbial keratitis in adults wearing soft contact lenses on an overnight basis.
Although they emphasised the need for further research, the authors concluded that the overall data support the safety of prescribing contact lenses for children.
Optom Vis Sci 2017; 94: 6: 638–646. doi: 10.1097/OPX.0000000000001078.