Fungi of the human eye: Culture to mycobiome.

The focus of the current review is multi-fold and compares the diversity and abundance of fungi on the ocular surface by the conventional culture-based method with the more sensitive, high throughput, culture-independent NGS method. The aim is to highlight the existence of a core ocular mycobiome and explore the transition of the ocular fungal microbiota from the normal eye to the diseased eye. PubMed, Google Scholar and Medline were used to search for publications and reviews related to cultivable fungi and the mycobiome of the normal and diseased eye. The conventional cultivable approach and the NGS approach confirm that the eye has its own mycobiome and several confounding factors (age, gender, ethnicity etc.) influence the mycobiome. Further, dysbiosis in the mycobiome appears to be associated with ocular diseases and thus impacts the health of the human eye. Considering that the mycobiome of the eye is influenced by several confounding factors and also varies with respect to the disease status of the eye there is a need to extensively explore the mycobiome under different physiological conditions, different ethnicities, geographical regions etc. Such studies would unravel the diversity and abundance of the mycobiomes and contribute to our understanding of ocular health. Research focused on ocular mycobiomes may eventually help to build a targeted and individualized treatment.

Clinical profile of pterygium in patients seeking eye care in India: electronic medical records-driven big data analytics report III.

OBJECTIVE: To describe the clinical profile of pterygium in patients presenting to a multi-tier ophthalmology hospital network in India. METHODS: This cross-sectional hospital-based study included 1,610,843 new patients presenting between 2010 and 2019. Patients with a clinical diagnosis of pterygium in at least one eye were included as cases. The data were collected using an electronic medical record system. Multiple logistic regression analysis with odds ratios (OR) was performed to identify the associated risk factors. RESULTS: Overall, 168,807 (10.5%) new patients were diagnosed with pterygium, of which 43,692 (26%) patients complained about the lesion. The prevalence rates were 0.7% in children and 12.6% in adults. Majority of patients were female (54.5%) and had unilateral (57%) affliction. Among the 241,631 affected eyes, the pterygia were primary in 99.6%, nasally located in 94%, and were grade I-II in 84.8%. Four in 5 eyes did not have any cylindrical refractive error, and 44% had coexistent cataract. Pterygium surgery was indicated in 10.3% eyes. Female sex (OR 1.37), increasing age (OR 19.5), rural residence (OR 1.21), agriculture work (OR 2.19), manual labor (OR 2.05), low socioeconomic status (OR 2.14) and geographical location closer to the equator (OR 3.4) were identified as the risk factors for developing pterygium. CONCLUSION: About one-tenth of individuals seeking eye care in India have pterygium in at least one eye. It rarely impacts vision, is commonly unilateral and nasal and usually does not require surgery. It is associated with increasing age, females, outdoor work, low income and geographical location closer to the equator.

Mycobiomes of the Ocular Surface in Bacterial Keratitis Patients.

Inflammation of the cornea is known as keratitis, and bacteria, fungi, protozoans, and viruses are the etiological agents of this disease. Delayed treatment of keratitis could result in loss of vision and, under certain severity conditions, the removal of an eye and its associated structures. In the current study, the ocular surface (conjunctiva and cornea) mycobiomes of individuals with bacterial keratitis were compared with the ocular mycobiome (conjunctiva) of healthy individuals, free of any ocular morbidity. Mycobiomes were generated through NGS approach using conjunctival swabs and corneal scrapings as the source of DNA from which ITS2 was amplified and sequenced, as a proxy to identify fungi. The results indicated significant changes in the alpha-diversity indices and in the abundance at the phylum and genera level. Hierarchical clustering using a heatmap showed that the mycobiomes were different. Furthermore, NMDS plots also differentiated the mycobiomes in the three cohorts, implying dysbiosis in the mycobiomes of the conjunctivae and corneal scrapings of bacterial keratitis individuals compared to control individuals. A preponderance of negative interactions in the hub genera in the conjunctival swabs of bacterial keratitis individuals compared to healthy controls further re-emphasized the differences in the mycobiomes. The dysbiotic changes at the genera level in conjunctivae and corneal scrapings of bacterial keratitis individuals are discussed with respect to their possible role in causing or exacerbating ocular surface inflammation. These results demonstrate dysbiosis in the ocular mycobiome in bacterial keratitis patients compared to healthy controls for the first time.

Biogeographical and Altitudinal Distribution of Cataract: A Nine-Year Experience Using Electronic Medical Record-Driven Big Data Analytics in India.

Purpose: To use electronic medical record data to study the altitude, UV exposure, and biogeographical distribution of senile cataract in India.Methods: This is a hospital-based, cross-sectional study of patients over 40 years old with an ophthalmologist-confirmed diagnosis of senile cataract (cortical, nuclear, posterior subcapsular, or a combination) in either or both eyes. Electronic medical record data entered between August 2010 to December 2019 were extracted from a large multi-tiered ophthalmology network in India. Residential districts were classified into their respective biogeographical zone based on nationally reported boundaries, and altitude at the geographic centroid was determined using Google Earth. Occupations were classified as low UV exposure and high UV exposure. Descriptive statistics, hypothesis testing, and multiple logistic regression analysis were done.Results: In the 1,127,232 eligible patients, associations were found between high UV exposure (OR = 1.47, 95%CI: 1.45-1.49), low socioeconomic status (OR = 1.54, 95%CI: 1.52-1.55), rural geographies (OR = 1.32), female gender (OR = 1.33, 95%CI: 1.32-1.34), and older age (OR≥3.98) with cataract. This Indian patient population did not demonstrate increased formation of cataracts at higher altitudes (OR≤0.97). Patients residing in the Deccan Peninsula (OR≥1.56) and those with high UV exposures within each increasing altitude category, except >750 m, (OR≥1.09) had higher odds of senile cataract comparatively.Conclusion: Female gender, occupations with high UV exposure, rural geography and increasing age were observed to have greater odds of developing senile cataract. Increased likelihood of cataracts in populations residing at low altitudes and within the Deccan Peninsula may be attributed to greater hospital development in those areas.

Clinical profile and magnitude of diabetic retinopathy: An electronic medical record-driven big data analytics from an eye care network in India.

PURPOSE: This study aimed to describe the clinical profile and magnitude of diabetic retinopathy (DR) in patients presenting to a multitier eye hospital network in India. METHODS: This cross-sectional hospital-based study included 263,419 individuals with diabetes mellitus (DM) presenting between February 2012 and February 2021 (9-year period). The data were collected using an electronic medical record (EMR). Patients with a clinical diagnosis of DR in at least one eye were included in the analysis. Severe nonproliferative DR/proliferative DR/diabetic macular edema (DME) were considered sight-threatening DR (STDR). RESULTS: In the study period, 25% (n = 66,913) were new patients diagnosed with DR. The majority of patients were males (70%). The mean age of the patients was 57 ± 10 years. The risk factors for DR were increased age: 30 to 50 years (odds ratio [OR] = 2.42), and 51 to 70 years (OR = 3.02), increased duration of DM: 6 to 10 years (OR = 2.88) and >10 years (OR = 6.52), blindness (OR = 2.42), male gender (OR = 1.36), lower socioeconomic status (OR = 1.43), and rural habitation (OR = 1.09). STDR was seen in 58% (n = 38,538) of examined patients. Risk factors for STDR were increased age 31 to 50 years (OR = 3.51), increased duration of DM: 6 to 10 years (OR = 1.23) and >10 years (OR = 1.68), blindness (OR = 3.68), male gender (OR = 1.12), and higher socioeconomic status (OR = 1.09). CONCLUSION: Every fourth person with DM was found to have DR, and every second person with DR had STDR in this study cohort. These real-world big data might provide greater insight into the current status of DR. Additional big data from similar EMR-based sources will help in planning and resource allocation.

Prevalence of chronic disease in older adults in multitier eye-care facilities in South India: Electronic medical records-driven big data analytics report.

PURPOSE: To study the prevalence of systemic conditions in older adults, either self-reported or discovered during routine eye examinations, at multitier eye-care facilities over the past decade, and to explore their association with vision and common ocular disorders, including cataract, glaucoma, and retinopathy. METHODS: Retrospective review of a large data set compiled from the electronic medical records of patients older than 60 years who presented to an eye facility of a multitier ophthalmology network located in 200 different geographical locations that included urban and rural eye-care centers spread across four states in India over a 10-year period. RESULTS: 618,096 subjects aged 60 or older were identified as visiting an eye facility over the 10-year study period. The mean age of the study individuals was 67·28 (±6·14) years. A majority of older adults (66·96%) reported being free of systemic illnesses. Patients from lower socioeconomic status had a lower prevalence of chronic systemic disease, but the presenting vision was poorer. Hypertension (21·62%) and diabetes (18·77%) were the most commonly reported chronic conditions in patients who had concomitant systemic illness with visual concerns. CONCLUSION: The prevalence of chronic systemic illnesses in older adults presenting to multitier eye-care facilities is relatively low, except in those with diabetic retinopathy. These observations suggest a need to include active screening for common chronic diseases in standalone eye-care facilities to achieve a more accurate assessment of chronic disease burden in the older population.

Factors protecting against diabetic retinopathy in a geriatric Indian cohort.

PURPOSE: Diabetic retinopathy (DR) is a potentially sight-threatening complication of diabetes mellitus. The majority of cases are in older adults. This study aims to evaluate modifiable and nonmodifiable protective factors against DR in a geriatric Indian population. METHODS: This retrospective observational study uses data from a multitiered ophthalmology network to evaluate several demographic and clinical variables against diabetic retinopathy and visual acuity. RESULTS: Our data show that high myopia, the female sex, and no cataract surgery are associated with lower prevalence of DR (OR = 0.21, 0.65, and 0.76, respectively; P < 0.001). We also found that among those with DR, people categorized as payers, retirees, and those living in urban or metropolitan areas have better visual acuity (OR = 0.65, 0.65, 0.83, and 0.73, respectively; P < 0.001). Among those with DR, females, presence of cataracts, and no cataract surgery had lower associations with sight-threatening DR (STDR) (OR = 0.68, 0.37, and 0.76, respectively; P < 0.001). Prevalence of DR decreased in older age groups while controlling for DM duration. CONCLUSION: It is probable that high myopia, the female sex, and better glycemic control are protective against DR and STDR in our study cohort of adults over 60 years of age. It is possible that occupations involving manual labor, delayed cataract surgery, and living past the age of 70 are also protective against DR.

Alterations in the gut bacterial microbiome in people with type 2 diabetes mellitus and diabetic retinopathy.

Gut bacterial microbiome dysbiosis in type 2 Diabetes Mellitus (T2DM) has been reported, but such an association with Diabetic Retinopathy (DR) is not known. We explored possible link between gut bacterial microbiome dysbiosis and DR. Using fecal samples of healthy controls (HC) and people with T2DM with/without DR, gut bacterial communities were analysed using 16S rRNA gene sequencing and data analysed using QIIME and R software. Dysbiosis in the gut microbiomes, at phyla and genera level, was observed in people with T2DM and DR compared to HC. People with DR exhibited greater discrimination from HC. Microbiomes of people with T2DM and DR were also significantly different. Both DM and DR microbiomes showed a decrease in anti-inflammatory, probiotic and other bacteria that could be pathogenic, compared to HC, and the observed change was more pronounced in people with DR. This is the first report demonstrating dysbiosis in the gut microbiome (alteration in the diversity and abundance at the phyla and genera level) in people with DR compared to HC. Such studies would help in developing novel and targeted therapies to improve treatment of DR.

Alterations in the Ocular Surface Fungal Microbiome in Fungal Keratitis Patients.

Keratitis, an inflammatory disease of the eye, when neglected could lead to sight-threatening complications and ultimately blindness. Globally, over a million people are affected by keratitis annually. Keratitis has a microbial etiology and is caused by bacteria, fungi, viruses, etc. The present study compared the ocular surface fungal microbiome of healthy individuals and individuals with fungal keratitis. Fungal microbiomes from the conjunctival swabs of healthy individuals and from conjunctival swabs and corneal scrapings of individuals with fungal keratitis were generated using ITS2 region amplicons. Microbiomes were sequenced using Illumina MiSeq 2 × 250 base pair chemistry with a paired-end protocol. Based on Alpha diversity indices, phylum and genera level diversity, abundance differences, and heat map analysis, the fungal microbiomes of conjunctival swabs and corneal scrapings of individuals with fungal keratitis exhibited dysbiosis (alterations in the diversity and abundance) compared to the ocular surface microbiome of the healthy control individuals. This is the first report indicating dysbiosis in the fungal microbiome of conjunctival swabs and corneal scrapings in individuals with fungal keratitis. A total of 11 genera present in the majority of the eyes constituted the variable core ocular microbiome.

Alterations in gut bacterial and fungal microbiomes are associated with bacterial Keratitis, an inflammatory disease of the human eye.

Dysbiosis, or imbalance in the gut microbiome, has been implicated in auto-immune, inflammatory, neurological diseases as well as in cancers. More recently it has also been shown to be associated with ocular diseases. In the present study, the association of gut microbiome dysbiosis with bacterial Keratitis, an inflammatory eye disease which significantly contributes to corneal blindness, was investigated. Bacterial and fungal gut microbiomes were analysed using fecal samples of healthy controls (HC, n = 21) and bacterial Keratitis patients (BK, n = 19). An increase in abundance of several antiinflammatory organisms including Dialister, Megasphaera, Faecalibacterium, Lachnospira, Ruminococcus and Mitsuokella and members of Firmicutes, Veillonellaceae, Ruminococcaceae and Lachnospiraceae was observed in HC compared to BK patients in the bacterial microbiome. In the fungal microbiome, a decrease in the abundance of Mortierella, Rhizopus, Kluyveromyces, Embellisia and Haematonectria and an increase in the abundance of pathogenic fungi Aspergillus and Malassezia were observed in BK patients compared to HC. In addition, heatmaps, PCoA plots and inferred functional profiles also indicated significant variations between the HC and BK microbiomes, which strongly suggest dysbiosis in the gut microbiome of BK patients. This is the first study demonstrating the association of gut microbiome with the pathophysiology of BK and thus supports the gut-eye axis hypothesis. Considering that Keratitis affects about 1 million people annually across the globe, the data could be the basis for developing alternate strategies for treatment like use of probiotics or fecal transplantation to restore the healthy microbiome as a treatment protocol for Keratitis.