The Rapid Assessment of Avoidable Blindness (RAAB) has been developed as a simple and rapidsurvey methodology that can provide data on the prevalence and main causes of blindness.AimTo assess the prevalence and main causes of avoidable blindness and visual impairment in peopleaged 50 and above in Mongolia.MethodsThe RAAB uses a standard methodology which is documented in the RAAB Instruction Manual (HansLimburg, International Centre for Eye Health, London School of Hygiene and Tropical Medicine).Assuming an estimated prevalence of blindness in persons aged 50+ of 2.14% and a non-complianceof 5%, with a variation to 25% around the estimate of 2.14% at 95% probability, the required samplesize was calculated at 4,040: 101 clusters of size 40. Visual acuity (VA) was measured with a Snellentumbling E chart, using optotype size 18 (60) on one side and size 60 (200) on the other side. Thelens status of all participants was assessed by both torch and distant direct ophthalmoscopy, by anophthalmologist in a shaded or dark environment. The data were analyzed using RAAB Version 4.02(ICEH, London) for pre-defined reports relating to both crude and age and gender adjusted results.ResultsThe survey included 4,040 people aged 50 years and older, of whom 4,029 were actually examined.The coverage was 99.7%. 7 persons (0.2%) were absent and 4 (0.1%) refused to participate in thestudy. The prevalence of bilateral blindness with available correction in the better eye is 2.2 % (95% CI,1.7 - 2.7%); 2.4% in males and 2.2% in females. The prevalence of bilateral severe visual impairment(SVI) is 2.1% and bilateral moderate visual impairment (MVI) is 10.8%. The prevalence of functionallow vision, requiring low vision services, is 4.5%. In people aged 50+, untreated cataract is the mostcommon cause of bilateral blindness with 38.9%, followed by glaucoma (20.0%), non-trachomatouscorneal opacity (13.3%), and other posterior segment disease (7.8%).Conclusion: Untreated cataract and uncorrected refractive errors are the major causes of avoidableblindness and low vision in Mongolia, respectively. Priority should be given to cataract surgery,followed by the development of optical services and PHC and PEC services, as these are the mostcost-effective interventions. These three interventions will address about three thirds (67.8%) of thecauses of blindness and have most impact.

To evaluate the efficacy and safety of bevacizumab monotherapy or combined with laser versus laser monotherapy in Mongolian patients with visual impairment due to diabetic macular edema.Prospective, randomized, single-center, a 12 month, laser-controlled, clinical trial. Participants: One hundred twelve eligible patients, aged ≥18 years, with type 1 or 2 diabetes mellitus and best corrected visual acuity (BCVA) in the study eye of 35 to 69 Early Treatment Diabetic Retinopathy Study (ETDRS)letters at 4 m (Snellen equivalent: ≥6/60 or ≤6/12), with visual impairment due to center-involved diabetic macular edema (DME). Methods: Patients were randomized into three treatment groups:(I) intravitreal bevacizumab monotherapy (n=42), (II) intravitreal bevacizumab combined with laser (n=35), (III) laser monotherapy (n=35). Bevacizumab injections were given for 3 initial monthly doses and then pro re nata (PRN) thereafter based on BCVA stability and DME progression. The primary efficacy endpoints were the mean change in BCVA and central retinal subfield thickness (CRST) from baseline to month 12.Bevacizumab monotherapy or combined with laser were superior to laser monotherapy in improving mean change in BCVA letter score from baseline to month 12 (+8.3 and +11.3 vs +1.1 letters; both p<0.0001). There were significant difference detected between the bevacizumab and bevacizumab combined with laser treatment groups (p=0.004). At month 12, greater proportion of patients gained ≥10 and ≥15 letters and with BCVA letter score >73 (Snellen equivalent: >6/12) with bevacizumab monotherapy (23.8% and 7.1% and 4.8%, respectively) and bevacizumab + laser (57.1% and 28.6% and 14.3%, respectively) versus laser monotherapy. The mean central retinal subfield thickness was significantly reduced from baseline to month 12 with bevacizumab (−124.4 μm) and bevacizumab + laser (−129.0 μm) versus laser (−62.0 μm; both p<0.0001). Conjunctival hemorrhage was the most common ocular events. No endophthalmitis cases occurred.Bevacizumab monotherapy or combined with laser showed superior BCVA improvements over macular laser treatment alone in Mongolian patients with visual impairment due to diabetic macular edema.