Visual Field Tests: A Narrative Review of Different Perimetric Methods.

Visual field (VF) testing dates back to fifth century B.C. It plays a pivotal role in the diagnosis, management, and prognosis of retinal and neurological diseases. This review summarizes each of the different VF tests and perimetric methods, including the advantages and disadvantages and adherence to the desired standard diagnostic criteria. The review targets beginners and eye care professionals and includes history and evolution, qualitative and quantitative tests, and subjective and objective perimetric methods. VF testing methods have evolved in terms of technique, precision, user-friendliness, and accuracy. Consequently, some earlier perimetric techniques, often still effective, are not used or have been forgotten. Newer technologies may not always be advantageous because of higher costs, and they may not achieve the desired sensitivity and specificity. VF testing is most often used in glaucoma and neurological diseases, but new objective methods that also measure response latencies are emerging for the management of retinal diseases. Given the varied perimetric methods available, clinicians are advised to select appropriate methods to suit their needs and target disease and to decide on applying simple vs. complex tests or between using subjective and objective methods. Newer, rapid, non-contact, objective methods may provide improved patient satisfaction and allow for the testing of children and the infirm.

Comparing 2-dimensional macular pigment optical density with objective and subjective perimetry and visual acuity in age-related macular degeneration.

PURPOSE: To compare diagnostic power for different severities of age-related macular degeneration (AMD) of two-dimensional macular pigment optical densities (2D-MPOD) and spatially matched objective perimetry, with standard perimetry and best-corrected visual acuity (BCVA). METHODS: The ObjectiveField Analyser (OFA) provided objective perimetry, and a Heidelberg Spectralis optical coherence tomography (OCT) measured 2D-MPOD in AMD patients, both completed twice over 0.99 ± 0.16 years. From each 2D-MPOD image, we extracted 20 regions/macula, matched to the 20 OFA stimuli/macula. For each region, we calculated 7 measures from the 2D-MPOD pixel values and correlated those with OFA sensitivities and delays. We quantified 2D-MPOD changes, the ability of 2D-MPOD and OFA to discriminate AMD stages, and the discriminatory power of Matrix perimetry and BCVA using percentage area under receiver operator characteristic plots (%AUROC). RESULTS: In 58 eyes of 29 subjects (71.6 ± 6.3 years, 22 females), we found significant correlations between 2D-MPOD and OFA sensitivities for Age-Related Eye Disease Studies (AREDS)-3 and AREDS-4 severities. Delays showed significant correlations with AREDS-2. For AREDS-4, correlations extended across all eccentricities. Regression associated with the Bland-Altman plots showed significant changes in 2D-MPOD over the study period, especially variability measures. MPOD per-region medians discriminated AREDS-1 from AREDS-3 eyes at a %AUROC of 80.0 ± 6.3%, outperforming OFA, Matrix perimetry, and BCVA. CONCLUSIONS: MPOD changes correlated with central functional changes and significant correlations extended peripherally in later-stage AMD. Good diagnostic power for earlier-stage AMD and significant change over the study suggest that 2D-MPOD and OFA may provide effective biomarkers.

Early diabetic eye damage: Comparing detection methods using diagnostic power.

It is now clear that retinal neuropathy precedes classical microvascular retinopathy in diabetes. Therefore, tests that underpin useful new endpoints must provide high diagnostic power well before the onset of moderate diabetic retinopathy. Hence, we compare detection methods of early diabetic eye damage. We reviewed data from a range of functional and structural studies of early diabetic eye disease and computed standardized effect size as a measure of diagnostic power, allowing the studies to be compared quantitatively. We then derived minimum performance criteria for tests to provide useful clinical endpoints. This included the criteria that tests should be rapid and easy so that children with type 1 diabetes can be followed into adulthood with the same tests. We also defined attributes that lend test data to further improve performance using Machine/Deep Learning. Data from a new form of objective perimetry suggested that the criteria are achievable.

Profile of Patients Treated with Intravitreal Anti-Vascular Endothelial Growth Factor Injections in Bhutan.

Purpose: Ocular vascular diseases are common causes of visual impairment and blindness, for which anti-vascular endothelial growth factor (anti-VEGF) is the first-line therapy. Current study describes the profile of patients receiving intravitreal anti-VEGF injections (IVI), and gender variation in Bhutan. The study was designed to inform national health policy. Study Design: Retrospective cross-sectional study. Methods: We reviewed the surgical registers of the vitreoretinal (VR) units across Bhutan over three years. Patient demography, clinical findings, diagnostic tests performed, and diagnoses or indications for IVI were logged. A descriptive analysis was performed. Results: Despite limited availability of anti-VEGF, a total of 381 patients received IVI in operating theatres as mandated by the national guidelines. The majority of patients were males (230, 60.4%, p = 0.004). The mean age was 65.2 ± 13.5 years (range 13 years to 90 years), and a median of 69 years. The majority of the treated eyes (117, 30.7%) had BCVA <3/60 to light perception (PL), and another 51 eyes (13.4%) had < 6/60 to 3/60. The most common indication for IVI was neovascular age-related macular degeneration (nAMD) (168 cases, 42.2%), followed by retinal vein occlusion (RVO) (132 cases, 34.6%), diabetic macular oedema (DMO) and retinopathy (DR) (50 cases, 13.1%), and myopic choroidal neovascular membrane (11 cases, 0.03%). Conclusion: Limited human resources for managing VR diseases in Bhutan are compounded by economic and geographic challenges. With increasing VR diseases such as nAMD and myopia and complications of systemic diseases such as DR, DMO and RVO, there is a need to improve VR services. Currently, anti-VEGF is procured only for a pooled patients requiring IVI, and patients are lost due to longer waiting periods. Bhutan needs to assess if females are reporting less or are not receiving treatment due to cultural barriers and social stigma.

Objective perimetry identifies regional functional progression and recovery in mild Diabetic Macular Oedema.

PURPOSE: Retinal function beyond foveal vision is not routinely examined in the clinical screening and management of diabetic retinopathy although growing evidence suggests it may precede structural changes. In this study we compare optical coherence tomography (OCT) based macular structure with function measured objectively with the ObjectiveFIELD Analyzer (OFA), and with Matrix perimetry. We did that longitudinally in Type 2 diabetes (T2D) patients with mild Diabetic Macular Oedema (DMO) with good vision and a similar number of T2D patients without DMO, to evaluate changes in retinal function more peripherally over the natural course of retinopathy. METHODS: Both eyes of 16 T2D patients (65.0 ± 10.1, 10 females), 10 with baseline DMO, were followed for up longitudinally for 27 months providing 94 data sets. Vasculopathy was assessed by fundus photography. Retinopathy was graded using to Early Treatment of Diabetic Retinopathy Study (ETDRS) guidelines. Posterior-pole OCT quantified a 64-region/eye thickness grid. Retinal function was measured with 10-2 Matrix perimetry, and the FDA-cleared OFA. Two multifocal pupillographic objective perimetry (mfPOP) variants presented 44 stimuli/eye within either the central 30° or 60° of the visual field, providing sensitivities and delays for each test-region. OCT, Matrix and 30° OFA data were mapped to a common 44 region/eye grid allowing change over time to be compared at the same retinal regions. RESULTS: In eyes that presented with DMO at baseline, mean retinal thickness reduced from 237 ± 25 µm to 234.2 ± 26.7 µm, while the initially non-DMO eyes significantly increased their mean thickness from 250.7 ± 24.4 µm to 255.7 ± 20.6 µm (both p<0.05). Eyes that reduced in retinal thickness over time recovered to more normal OFA sensitivities and delays (all p<0.021). Matrix perimetry quantified fewer regions that changed significantly over the 27 months, mostly presenting in the central 8 degrees. CONCLUSIONS: Changes in retinal function measured by OFA possibly offer greater power to monitor DMO over time than Matrix perimetry data.

The experience of visual art for people living with mild-to-moderate vision loss.

BACKGROUND: Visual art can enhance wellbeing and quality-of-life; however, the experience of visual art for people with mild-to-moderate vision loss has not been examined. METHODS: Eight participants (6 females, 2 males; Mean age = 81 years, SD = 7.9, range 70-91 years; 4 with mild vision loss and 4 with moderate vision loss based on binocular visual acuity) completed a mixed-methods study comprising: a semi-structured interview on visual art experience; an eye examination; and questionnaires about visual functioning and quality-of-life. RESULTS: Various themes were identified: visual perception of art (e.g. altered colours, visual distortions, etc.), viewing conditions, elements of art, personal preference, deriving meaning, appreciation of art, impact of impaired visual perception, and social aspects of art. CONCLUSIONS: The overall experience of art is influenced by how an individual sees, perceives, and makes meaning from art. Even mild vision loss can impair this experience and impact emotional and social wellbeing.

Prevalence and severity of diabetic retinopathy at first presentation to vitreoretinal services in Bhutan: a 3-year national study.

PURPOSE: To determine the prevalence and severity of diabetic retinopathy (DR) at first presentation among diabetic patients attending national vitreoretinal (VR) services in Bhutan STUDY DESIGN: Retrospective cross-sectional study METHODS: We included all diabetic patients in Bhutan who presented for retinal evaluation for the first time over a 3-year period (2013-2016). Data including demography, clinical details, diagnostic tests, and clinical staging of DR were analyzed. RESULTS: A total of 843 diabetic patients, aged 57.2 ± 12.0 (range 18-86) years, were enrolled. The majority were male (452, 53.6%; cumulative frequency [cf] 391, 46.4%; P = .14) and from urban settings (570, 67.6%; cf 273; 32.4%) and did not have modern schooling (555, 65.8%). Hypertension was the most common systemic comorbidity (501, 59.4%). The prevalence of DR was 42.7%, with mild nonproliferative DR (NPDR) being the most common type (187, 51.9%), followed by moderate NPDR (88, 24.4%) and proliferative DR (45, 12.5%). In addition, 120 patients had clinically significant macular edema (CSME), with a prevalence of 14.2%. Best-corrected visual acuity (BCVA) of 6/60 or worse occurred in 231 eyes (13.7%), and 41 patients (4.86%) had BCVA of 6/60 or worse bilaterally due to DR/CSME. A logistic regression model indicated that the major determinant of DR was the duration of diabetes, the odds rising by 1.27× with each year of disease (P < .0001). CONCLUSION: The prevalence of DR, including CSME, was high. Although a national DR screening program is established in Bhutan, there is a need to accelerate health education, community screening, and referral systems to reduce the prevalence of DR and CSME.

Incidence and Pattern of Neuro-Ophthalmological Disorders Presenting to Vitreoretinal Clinics in Bhutan: A 3-Year National Study.

Purpose: To inform national health policy, we quantified the pattern of neuro-ophthalmological disorders (NODs) presenting to the national vitreoretinal clinics in Bhutan. Study Design: Retrospective cross-sectional study. Methods: We reviewed all new NODs patients over three years. Demographic data, presenting complaints, treatment history, systemic diseases, diagnostic procedures, and diagnoses were quantified. Logistic regression examined the odds of factors linked to more common NODs. Results: Of 226 patients, the majority were males (54.0%), farmers (60.2%), and urbanites (55.8%). Loss of vision was the most common presenting complaint (57.9%), followed by head or orbital trauma (19.5%). The best corrected visual acuity (BCVA) of 216 eyes (47.8%) was ≤6/60. Hypertension was the most common systemic disease (16.4%), followed by diabetes (3.5%), and intracranial space-occupying lesions (3.5%). Neuroimaging (37.6%) was the most common diagnostic test performed, followed by visual field testings (VFTs) (22.9%). With a NOD incidence of 7.8% p.a. (226/2913), optic atrophy (OA) was diagnosed in 134 patients (59.3%). Other common NODs were optic neuritis (15.5%), papilloedema (9.3%), and traumatic optic neuropathy (8.4%). Female gender increased the odds for glaucomatous OA by 2.65× (p = 0.044), and age by 1.09× per year (p < 0.001). Being female increased the odds of optic neuritis by 2.57× (p = 0.03). Conclusion: Over half of the NODs were OA, which could be curable with timely treatment. Improved treatment of glaucoma and non-communicable diseases would reduce the risk of NODs-induced visual loss in Bhutan. The need for improved neuro-ophthalmological assessment and a coordinated multidisciplinary approach to NODs are the highest priorities.

Rapid, non-contact multifocal visual assessment in multiple sclerosis.

OBJECTIVE: Previous work on temporally sparse multifocal methods suggests that the results are correlated with disability and progression in people with multiple sclerosis (PwMS). Here, we assess the diagnostic power of three cortically mediated sparse multifocal pupillographic objective perimetry (mfPOP) methods that quantified response-delay and light-sensitivity at up to 44 regions of both visual fields concurrently. METHODS: One high-spatial-resolution mfPOP method, P129, and two rapid medium-resolution methods, W12 and W20, were tested on 44 PwMS and controls. W12 and W20 took 82 s to test both visual fields concurrently, providing response delay and sensitivity at each field location, while P129 took 7 min. Diagnostic power was assessed using areas under the receiver operating characteristic (AUROC) curves and effect-size (Hedges' g). Linear models examined significance. Concurrent testing of both eyes permitted assessment of between-eye asymmetries. RESULTS: Per-region response delays and asymmetries achieved AUROCs of 86.6% ± 4.72% (mean ± SE) in relapsing-remitting MS, and 96.5% ± 2.30% in progressive MS. Performance increased with increasing disability scores, with even moderate EDSS 2 to 4.5 PwMS producing AUROCs of 82.1 to 89.8%, Hedge's g values up to 2.06, and p = 4.0e - 13. All tests performed well regardless of any history of optic neuritis. W12 and W20 performed as well or better than P129. CONCLUSION: Overall, the 82-s tests (W12 and W20) performed better than P129. The results suggest that mfPOP assesses a correlate of disease severity rather than a history of inflammation, and that it may be useful in the clinical management of PwMS.

Rapid Objective Testing of Visual Function Matched to the ETDRS Grid and Its Diagnostic Power in Age-Related Macular Degeneration.

Purpose: To study the power of an 80-second multifocal pupillographic objective perimetry (mfPOP) test tailored to the ETDRS grid to diagnose age-related macular degeneration (AMD) by Age-Related Eye Disease Study (AREDS) severity grade. Design: Evaluation of a diagnostic technology. Methods: We compared diagnostic power of acuity, ETDRS grid retinal thickness data, new 80-second M18 mfPOP test, and two wider-field 6-minute mfPOP tests (Macular-P131, Widefield-P129). The M18 stimuli match the size and shape of bifurcated ETDRS grid regions, allowing easy structure-function comparisons. M18, P129, and P131 stimuli test both eyes concurrently. We recruited 34 patients with early-stage AMD with a mean ± standard deviation (SD) age of 72.6 ± 7.06 years. The M18 and P129 plus P131 stimuli had 26 and 51 control participants, respectively with mean ± SD ages of 73.1 ± 8.17 years and 72.1 ± 5.83 years, respectively. Multifocal pupillographic objective perimetry testing used the Food and Drug Administration-cleared Objective FIELD Analyzer (OFA; Konan Medical USA). Main Outcome Measures: Percentage area under the receiver operator characteristic curve (AUC) and Hedge's g effect size. Results: Acuity and OCT ETDRS grid thickness and volume produced reasonable diagnostic power (percentage AUC) for AREDS grade 4 eyes at 83.9 ± 9.98% and 90.2 ± 6.32% (mean ± standard error), respectively, but not for eyes with less severe disease. By contrast, M18 stimuli produced percentage AUCs from 72.8 ± 6.65% (AREDS grade 2) to 92.9 ± 3.93% (AREDS grade 4), and 82.9 ± 3.71% for all eyes. Hedge's g effect sizes ranged from 0.84 to 2.32 (large to huge). Percentage AUC for P131 stimuli performed similarly and for P129 performed somewhat less well. Conclusions: The rapid and objective M18 test provided diagnostic power comparable with that of wider-field 6-minute mfPOP tests. Unlike acuity or OCT ETDRS grid data, OFA tests produced reasonable diagnostic power in AREDS grade 1 to 3 eyes.

Severity of age-related macular degeneration at first presentation in Bhutan: a 3-year national study.

BACKGROUND: Medical services are still developing in Bhutan. There is no published national report on age-related macular degeneration (AMD). We therefore aim to determine the demographic characteristics and severity of AMD at first presentation among Bhutanese patients attending their recently inaugurated vitreoretinal (VR) clinics over a 3-year national survey, and to inform national health policy to develop suitable health program to prevent AMD-related blindness and visual impairment. METHODS: A retrospective cross-sectional consecutive case series study was conducted on all new AMD cases in Bhutan. If a patient presented with asymmetrical AMD, the eye with more severe AMD was considered. If both the eyes had the same severity one eye was chosen randomly. Collection of demographic data and clinical details including diagnostic testing (fundus photography, OCT and fluorescent angiography) and clinical staging were performed. RESULTS: Of 521 new AMD patients aged 71.9 ± 11.3 years, 306/521 (58.7%) were males (p = 0.005). At their first presentation, 234/521 patients (44.9%) already had late-stage AMD. Importantly, 69/234 patients (29.5%), that is half of total neovascular AMD (nAMD) patients, had disciform scars (DS) which were beyond treatment, and 7/234 patients (3.0%) had geographic atrophy (GA). Seven patients had retinal pigment epithelium tear at presentation. Fourteen of nineteen polypoidal choroidal vasculopathy (PCV) patients were younger than 50 years. CONCLUSIONS: Half of nAMD cases presented as DS not amenable to the treatment. Many potentially treatable nAMD patients had already lost central vision and were legally blind. Young people with PCV losing vision early in life with longer morbidity-affected life and socio-economic burden was concerning. GA and DS cases need visual rehabilitation to improve their QoL. Incorporating a screening program for AMD with effective health education, and maintaining a national AMD Registry, would potentially lower AMD-related blindness and visual impairment.

An Objective Perimetry Study of Central Versus Peripheral Sensitivities and Delays in Age-Related Macular Degeneration.

Purpose: The purpose of this study was to compare central versus peripheral retinal sensitivities and delays in neovascular age-related macular degeneration (nAMD) using US Food and Drug Administration (FDA)-cleared multifocal pupillographic objective perimetry (mfPOP). Methods: We recruited 18 patients with nAMD and commenced Pro re nata intravitreal anti- vascular endothelial growth factor (VEGF) injection. We compared macular (±15 degrees) and wide-field (±30 degrees) mfPOP variants. We examined temporal correlations between treated and untreated fellow eyes. We fitted linear models to selected treatment patterns, and compared the ability of central versus peripheral responses to predict the need for treatment. Results: Central sensitivity decreased by -2.23 ± 0.051 dB/month (P < 0.0002) in treated eyes, and -0.17 ± 0.07 dB/month (P = 0.033) in untreated eyes. Treated eyes showed quicker central responses by 13.08 ± 3.77 ms than untreated eyes (P = 0.001). Based on peripheral responses, we identified two eye-types. Among positive-eyes peripheral sensitivity increased by 9.88 ± 4.41 dB (P = 0.042) before treatment; delays increased by 3.49 ± 1.75 ms/month (P = 0.049). For negative-eyes peripheral delays were shorter a month before treatment by 9.38 ± 3.59 ms (P = 0.013). Correlations between treatment and peripheral sensitivities or delays peaked at 1 to 2 months post-treatment. Peripheral data significantly determined treatment frequency and final acuity (all P < 0.044). Conclusions: Peripheral macular function of treated and untreated eyes divided eyes into positive and negative groups. Those peripheral responses determined outcomes; changes preceding active disease by 1 to 3 months. Overall, mfPOP may provide potential biomarkers to assist nAMD management. Translational Relevance: Objective perimetry may identify the requirement for treatment in nAMD that accords with the decision of a skilled clinician based on optical coherence tomography (OCT) and clinical findings.

Comparing Objective Perimetry, Matrix Perimetry, and Regional Retinal Thickness in Mild Diabetic Macular Edema.

Purpose: To compare per-region macular sensitivity and delay from objective perimetry with Matrix perimetry and retinal thickness in mild diabetic macular edema (DMO). Methods: Thirty-three patients with type 2 diabetes (T2D) aged 59.2 ± 10.5 years participated in a longitudinal study. Macular thickness, sensitivities and delays from the objectiveFIELD Analyzer (OFA), and Matrix perimeter sensitivities were mapped onto a common spatial layout to compute per-region correlations between structure/function measures. A generalized linear mixed-effects logistic regression model determined which variables contributed to clinical diagnosis of DMO. Results: For OFA, the mean sensitivity differences compared with normal in patients with T2D were negative and the mean delay differences positive, indicating lowered sensitivities and prolonged delays, both increasing with diabetes duration. Shorter diabetes duration could produce either localized peripheral hypersensitivities or shorter delays. Functional change could occur when retinal thickness was stable. Peripheral macular thickness correlated with central and peripheral OFA sensitivity and delay, all P < 0.0012 in DMO and a median of P = 0.001 without DMO; this was not true for Matrix sensitivities. The logistic model determined that peripheral thickness, OFA sensitivity (P = 0.043), and time in the study (P = 0.001) contribute independently to the odds of DMO versus no DMO. Conclusions: Mean sensitivities decreased and mean delays increased with duration of diabetes. Peripheral macular thickness correlated significantly with central and peripheral macular OFA sensitivity and delay. Peripheral macular thickness and functional measures may provide sensitive prognostic data. Translational Relevance: Functional loss can precede structural change in DMO, so including such functional assessment for deciding on treatment may be beneficial.

Correlation of Central Versus Peripheral Macular Structure-Function With Acuity in Age-Related Macular Degeneration.

Purpose: Patients with advanced age-related macular degeneration (AMD) may have preserved visual function despite significant retinal structural changes. We aimed to evaluate the relationships among retinal thickness, macular sensitivity, and visual acuity (VA) in advanced AMD. Methods: We examined 43 eyes of 22 patients with advanced AMD (ages 66-93 years), prospectively recruited from the Canberra Hospital Ophthalmology Department. Visual function was measured on participants with low and high contrast visual acuity (LCVA and HCVA) and 10-2 Matrix visual fields. Retinal structure was determined with spectral domain optical coherence tomography (OCT), and customized software mapped the 64 OCT macular thickness regions onto the 44 regions of the 10-2 test. Results: Median retinal thickness at each 10-2 region was near normal. Just 7 of 88 regions from the OCT analysis that were thicker than the median had sensitivity that declined significantly with increasing thickness (r = -0.698 ± 0.082, mean ± SD), whereas 17 of 88 thinner regions showed significantly decreasing sensitivity with decreasing thickness (r = 0.723 ± 0.078). The absolute value of deviations from median optical coherence tomography thickness (aOCT) outside the central eight degrees was significantly correlated with HCVA (r = -0.34, P = 0.047). Thickness in the central eight degrees was not. Similarly, matrix sensitivities inside the central eight degrees were significantly correlated with outer aOCT (r = -0.49, P = 0.002). Conclusions: Retinal thickness outside eight degrees were significantly associated with HCVA and macular sensitivity. These results suggest that outer macular thickness may be a useful prognostic indicator in AMD. Translational Relevance: Retinal structure at the borders of the macula may be a surrogate marker of vision and retinal thickness near fixation.

Hepatitis C Virus Infection in Pregnancy and Children: Its Implications and Treatment Considerations with Directly Acting Antivirals: A Review.

Hepatitis C virus infection (HCV) is a global health problem affecting >71 million people worldwide with chronic hepatitis C, 40% reproductive age group, and 8% pregnant women. Intravenous drug abuse, multi-transfusions are major risk factors in adults, while vertical transmission in pediatric population. It commonly presents as a chronic liver disease, has higher risk of liver cirrhosis and even progression to hepatocellular carcinoma. Therefore, proper screening of high-risk populations including pregnancy is recommended. All diagnosed chronic hepatitis C cases should be treated with directly acting anti-virals (DAAs) including pre-conception which has a cure rate of >95%. This would reduce the disease burden, vertical transmission, and disability associated. However, no DAAs regimens recommendation till date due to lack of evidence on adverse fetal outcomes and are concerned about the pharmacokinetic effect regarding physiological changes during pregnancy. Therefore, in this review, we have tried to explore the possible use of DAAs regimens and their safety issues during pregnancy, and possible consideration of few pan-genotypic regimens in the late 2nd and early 3rd trimester. This would not only prevent vertical transmission and decrease disease burden but also help to meet the WHO 2030 target of HCV elimination as a major public health problem.

Rural-urban differences in myopia prevalence among myopes presenting to Bhutanese retinal clinical services: a 3-year national study.

PURPOSE: To determine the prevalence and demographic characteristics of myopia among patients presenting to the national vitreo-retinal (VR) services in Bhutan. METHODS: The records of the VR clinic at the apex national referral centre, providing the only VR services in the country, were reviewed to identify all new myopia patients over three years. Thus, we surveyed all referrals nationally. The patients were categorised into urban and rural females and males. We assessed myopia prevalence in each group by occupational and educational categories. We examined univariate prevalence data and a multivariate logistic regression (MLR) identified independent factors. RESULTS: Of 2913 cases 1544 (53.0%) were males. Females presented earlier (mean ±SD): overall 45.7 ± 21.9 cf. 48.6 ± 21.6 years, p = 0.003, and among myopes 23.9 ± 13.5 cf. 27.6 ± 18.6 years, p = 0.032. Myopia constituted 92.1% of refractive error, an overall prevalence of 12.3%. Myopia was more common among females (p = 0.01) and urbanites (p = 0.02). Myopia prevalence was highest among urban females (20.9%), followed by urban males (11.9%), rural females (6.8%), and rural males (5.2%). Logistic regression revealed that the odds of having myopia were increased by being a student (4.96 ×) or professional (1.96 ×), and decreased by rural living (1.75 ×), all p ≤ 0.038. CONCLUSIONS: This is the first study on myopia in Bhutan. As observed throughout East and Southeast Asia, the prevalence of myopia was higher in females and urbanites and positively associated with formal education. Given known risk factors, these prevalences may be driven by educational pressures and reduced time spent outdoors.

Retinal laser services in Bhutan: a 3-year national survey.

BACKGROUND: We conducted this study to report on the indications and types of retinal laser therapy (RLT) performed in Bhutan, knowing which is critical for proper planning and successful delivery of the services. METHODS: We reviewed the laser registers maintained in the laser rooms and vitreoretinal (VR) operating theatres (including paediatric cases managed under anaesthesia) over three years at the national and the two regional referral hospitals (RRHs). Intraoperative laser treatments (endolaser) were excluded. Patient demography, indications and types of RLT were recorded and quantified. Comparisons of the expected and observed frequencies used Chi-squared tests. RESULTS: A total of 685 patients, including 8 cases of bilateral retinopathy of prematurity (ROP) received RLT. The majority of patients (411 cases, 60.0%, p < 0.0001) were males. The mean age was 54.1 ± 14.1 years, median 56 years. The most common indications for RLT were diabetic retinopathy (DR) and diabetic macular oedema (DMO) (542 cases, 66.0%), followed by retinal vein occlusion (RVO) (91 cases, 13.3%). Pan-retinal photocoagulation was the most common type of RLT performed (337 cases, 49.2%), followed by modified grid laser (207 cases, 30.2%), sectoral laser (41 cases, 6.0%), and prophylactic laser photocoagulation (33 cases, 4.8%). CONCLUSIONS: The majority of patients were within working-age. Common indications for RLT were preventable such as DR, DMO and RVO, indicating need to control systemic diseases such as diabetes, hypertension, and dyslipidaemia. Currently, regular RLT is provided only at the national referral hospital in Thimphu, and periodically in the eastern and central RRHs when the retinal specialist visits. There is need to extend the retinal services to the eastern and central RRHs to improve accessibility and patient coverage in these regions challenged with difficult terrain and poor public transport system.

Pattern of vitreo-retinal diseases at the national referral hospital in Bhutan: a retrospective, hospital-based study.

BACKGROUND: Knowing the pattern and presentation of the diseases is critical for management strategies. To inform eye-care policy we quantified the pattern of vitreo-retinal (VR) diseases presenting at the national referral hospital in Bhutan. METHODS: We reviewed all new patients over three years from the retinal clinic of the Jigme Dorji Wangchuck National Referral Hospital. Demographic data, presenting complaints and duration, treatment history, associated systemic diseases, diagnostic procedures performed, and final diagnoses were quantified. Comparisons of the expected and observed frequency of gender used Chi-squared tests. We applied a sampling with replacement based bootstrap analysis (10,000 cycles) to estimate the population means and the standard errors of the means and standard error of the 10th, 25th, 50th, 75th and 90th percentiles of the ages of the males and females within 20-year cohorts. We then applied t-tests employing the estimated means and standard errors. The 2913 subjects insured that the bootstrap estimates were statistically conservative. RESULTS: The 2913 new cases were aged 47.2 ± 21.8 years. 1544 (53.0%) were males. Housewives (953, 32.7%) and farmers (648, 22.2%) were the commonest occupations. Poor vision (41.9%), screening for diabetic and hypertensive retinopathy (13.1%), referral (9.7%), sudden vision loss (9.3%), and trauma (8.0%) were the commonest presenting symptoms. Coexistent diabetes and hypertension were the most common associated systemic diseases. Haematological tests (blood sugar, HbA1c and lipid profile, 31.8%), OCT (27.4%), refraction (9.9%), B-scan (8.7%), fundus photography (8.0%) were the most commonly performed diagnostic tests. Hypertensive retinopathy (18.9%) was the commonest VR disease, followed by refractive errors referred for retinal evaluation (16.7%), diabetic retinopathy with macular oedema (15.8%), and AMD (11.0%). Retinal detachment was more prevalent in females (83 vs. 41, p = 0.007). Rare vision-threatening diseases like seasonal hyper-acute pan-uveitis also presented. CONCLUSIONS: The developing VR service in Bhutan is challenged by the spectrum of diseases, limited human resources (e.g. one retinal surgeon during the study), and accessibility to tertiary eye-care services, all amidst difficult terrain. Sustained effort and robust coordination among the eye-care professionals, government and non-governmental organisations are critical for optimising VR services, especially as rates of diseases such as diabetes and hypertension grow.

Recovery dynamics of multifocal pupillographic objective perimetry from tropicamide dilation.

PURPOSE: To study the pupillary system by combining mydriasis and multifocal pupillographic objective perimetry (mfPOP). In particular, we explored how the dynamics of recovery differ for concurrently measured direct and consensual sensitivity, response delay, and signal-to-noise ratios (SNRs) for binocular mydriasis. METHODS: We recruited 26 normal participants, all with brown irides. The dichoptic mfPOP stimuli concurrently assessed 44-region/eye and both pupils. Two pre-dilation tests were followed by pairs of repeated tests at 1, 2, 4, 6, 8, 12, 24, and 48 h following dilation of both pupils with 1% tropicamide. Three subjects were retested with only the right pupil dilated. Linear models determined the independent effects of mydriasis upon the per-region and pupil measures over time. RESULTS: Post-dilation, the per-region delays initially decreased by 16.3 ± 6.02 ms (mean ± SE) (p < 0.0001, cf. baseline of 471.1 ± 4.36 ms), then increased to slower than baseline by 17.42 ± 5.57 ms after 4 h (p < 0.002), recovering to baseline at 8 h. By comparison, per-region sensitivities (constriction amplitudes) were still reduced by - 6.20 ± 0.70 µm at 8 h (p < 0.0001, cf. baseline of 21.1 ± 0.55 µm), recovered at 24 h, but rebounded at 48 h (p = 0.005). The SNRs for sensitivities and delays both recovered by 8-12 h. Across all the data, sensitivities reduced by 2.67 ± 0.25 µm/decade of age, and delay increased by 15.4 ± 1.98 ms/decade (both p < 0.00001). Data from 3 of the 26 subjects who repeated the testing for monocular dilation found that consensual response sensitivities were larger than direct for 8 h (p < 0.018). CONCLUSIONS: The per-region sensitivities were affected for longer than SNRs or delays. Strong early SNRs indicated proportionately lower pupil noise for larger pupil diameters. Following mydriasis with tropicamide 1%, the constriction amplitude measurements with mfPOP should be considered only after 48 h, but time-to-peak can be measured after 8-12 h.

Pattern and Presentation of Vitreo-Retinal Diseases: An Analysis of Retrospective Data at a Tertiary Eye Care Center in Nepal.

PURPOSE: We examined patients presenting in a tertiary eye hospital in Nepal, focusing on information relevant to screening and management programs for vitreo-retinal (VR) disease. DESIGN: Retrospective, cross-sectional study. METHODS: We reviewed all patients presenting for the first time to the VR-clinic over 1 year. We quantified patient demography, symptoms and duration, systemic diseases, ophthalmological examinations, diagnostic investigations, and final diagnoses. RESULTS: Of the 1905 cases, 1148 were male (60.3%). The 25th percentile of ages was 29 and 38 years for male and female, respectively; thus, female presented later (P < 0.0001). Hypertension was the commonest systemic disease (40.8%), followed by diabetes (32.5%). Age-related macular degeneration (AMD) and diabetic retinopathy (DR) affected 447 eyes (11.8%) and 416 eyes (10.9%), respectively. Male and female AMD and DR patients did not differ in age or disease duration. Similarly, age or disease duration for DR did not correlate with severity. Asymmetry of disease severity between eyes with AMD and DR was largest in patients with 1 normal eye. Presenting acuity was asymmetric between eyes (P < 0.0001) with people more often reporting once their right eyes had acuity of 6/18 or worse. CONCLUSIONS: The screening of blood pressure and glucose levels combined with fundus photography could prevent many from progressing to life-changing visual impairment and blindness. Later reporting by females began at childbearing age; therefore, education and ocular screening could be usefully coupled in reproductive health programs. Clubbing VR disease screening with other established health programs like diabetes control program, hypertension clinics, school health program, and so on, would provide economical and sustainable approach.