Vitamin deficiencies and glaucoma
Vitamins play a major role in health, and their deficiency has been linked to symptoms of optic-nerve dysfunction. Howvere the association between serum vitamin levels and glaucoma in humans has remained controversial. To evaluate this, a meta-analysis and review of 9 studies on primary openangle glaucoma (POAG), 
4 studies on normal tension glaucoma (NTG), and 6 studies on exfoliative glaucoma (EXG) was performed. The results showed no differences in the levels of serum vitamin B6 between POAG (p = 0.406) and EXG (p = 0.139) patients and controls. There was also no difference between POAG (p = 0.952), NTG (p = 0.757), or EXG (p = 0.064) patients and controls in terms of serum vitamin B12 and likewise serum vitamin D levels exhibited no differences (p = 0.064) between POAG patients and controls. The authors concluded that there was no association found between serum vitamin B6, vitamin B12, or vitamin D levels and the different types of glaucoma.
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Li S, Li D, Shao M, Cao W, Sun X. Lack of Association between Serum Vitamin B6, Vitamin B12, and Vitamin D Levels with Different Types of Glaucoma: A Systematic Review and Meta-Analysis. Nutrients. 2017 Jun 21;9(6).
Your glaucoma patient is at risk for stroke
A long term study to evaluate the risk of stroke in patients with normal tension glaucoma was published recently. Normal tension glaucoma is supposed to be secondary to vascular insufficiency of the optic nerve and hence may be a predictor for stroke. A populationbased retrospective cohort study from Taiwan evaluated 1,218 patients with NTG who were 20 years of age and older. Patients’ age, gender and pre-existing comorbidities, including hypertension, diabetes, congestive heart failure, ischemic heart disease, atrial fibrillation and disorders of lipid metabolism, were recorded. The study was designed to minimize screening bias and targeted to calculate the hazard ratio (HR) of developing stroke between the NTG and control groups. After adjusting for patient age, gender, and pre-existing comorbidities, the HR was 6.34, indicating that the incidence of stroke was significantly higher in patients with NTG than in controls. Furthermore, a higher risk of stroke was also found in most subgroups with systemic comorbidities. The study indicates a need for early interventions for stroke prevention for newly diagnosed patients with NTG.
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Lee MS, Kuo LL, Tan EC, Lee OK. Is normaltension glaucoma a risk factor for stroke?-A 10-year follow-up study. PLoS One. 2017 Jun 19;12(6)
Long term incidence of field loss in open angle glaucoma
Two decades after the start of the Rotterdam study, a lot has been learnt about glaucoma and its outcomes. A recent publication in the European journal of Epidemiology evaluates the incidence of glaucomatous visual field loss (GVFL). Of the 6806 participants aged 55 years and older from the population-based Rotterdam Study, 3939 had undergone a visual field testing at baseline and at least one follow-up visit. Additionally, optic disc assessment and measurements of intraocular pressure (IOP), refractive error, diastolic blood pressure (DBP), and height and weight were examined. The incidence rate of GVFL was calculated over a median follow up of 11 years. The incidence rate of GVFL was found to be 2.9 (95% CI 2.4-3.4) per 1000 person years (140 cases with incident GVFL in one (n = 113) or both (n = 27) eyes). Baseline IOP and age were significantly associated with all outcomes (all p < 0.001); BMI showed a non-significant protective effect in all outcomes (p = 0.01 to p = 0.09). Gender, myopia, and DBP were not associated with any outcome. This study showed an estimate of the long-term incidence of GVFL in a Caucasian population.
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Springelkamp H, Wolfs RC, Ramdas WD, Hofman A, Vingerling JR, Klaver CC, Jansonius NM. Incidence of glaucomatous visual field loss after two decades of follow-up: the Rotterdam Study. Eur J Epidemiol. 2017 Jun 12.
Self-Tonometry: More reliable than we thought
The ability of patients to measure their own intramuscular pressure (IOP) would allow more frequent measurements and better appreciation of peak IOP and IOP fluctuation. It is the ideal situation if a reliable self-measurement of IOP is possible. Pronin et al examined this aspect of glaucoma management by evaluating whether the rebound tonometer can be reliably and comfortably used for the self-assessment. An observational study in which IOP was assessed using Goldmann applanation tonometry and a rebound tonometer was performed in 100 consecutive patients. Patients were provided with a patient information sheet and those consenting to take part in the study received standardized self-tonometry training and were then instructed to measure their own IOP under observation in the clinic. Complete success was defined by a good technique and an IOP reading within 5 mm Hg of that obtained by a clinician using the same device. A 3-item questionnaire was used to examine perceptions of self-tonometry among patients. A total 73 of 100 patients (73%) met the complete success criteria. An additional 6 patients could use the device but had IOP readings greater than 5 mm Hg different from those obtained by the clinician. A total of 56 of 79 successful or partially successful patients (71%) felt self-tonometry was easy, with 73 of 79 (92%) reporting self-tonometry to be comfortable. The study concluded that most patients could perform self-tonometry and the method was acceptable to patients. Self-tonometry is a reliable technique when using the rebound tonometer after some patient training.
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Pronin S, Brown L, Megaw R, Tatham AJ. Measurement of Intraocular Pressure by Patients With Glaucoma. JAMA Ophthalmol. 2017 Aug 31.