OphthatomeTM contains clinical and phenotype data of 581,466 cases (males - 318,383, females - 263,083) with 524 distinct ophthalmic disease types and 1800 disease sub-types.
The knowledgebase comprises diseases affecting 35 different anatomical parts of the orbit, lids and the eye including the anterior segment, posterior segment and eye adnexa. Figure 2A summarizes the number of patient data available for various diseases affecting different parts of the eye. The knowledgebase includes comprehensive ophthalmic clinical variables such as refraction, intraocular pressure, central corneal thickness, slit-lamp examination details, diagnosis, prescription medications, surgical interventions, and thirteen clinical diagnostic images. The available clinical variables for each case were mapped longitudinally starting with the most recent value. OphthatomeTM is unique as it contains curated quantitative trait datapoints. Of the total of 12,234,278 quantitative datapoints (RE, IOP, CCT), 9,240,394 (77%) were within the defined range of value for the trait. Manual curation added 506,500 (5%) datapoints resulting in a total of 9,926,894 (82%) accurate datapoints (Figure 1).
Analysis of age-related ocular diseases
The top 25 ophthalmic diseases affecting <18 years (paediatric cases), >50 years and for the overall cohort are given in figure 2B, 2C, 2D respectively. A comparison between the two age groups, show that refractive error is equally prevalent in both the groups (46,569/102,590 paediatric cases and 271,147/478,876 cases in the >18 years age group), whereas presbyopia, which is a condition associated with age are completely absent in ≤18 years old and is diagnosed in 217,765 cases >18 years age. Similarly, late-onset eye disease, like age-related macular degeneration was completely absent in the paediatric group as expected and is reported in 2166 cases of >18 years age. Conversely, retinopathy of prematurity and retinoblastoma is reported in the paediatric group only (4695 and 213 cases, respectively) and completely absent in the adult. Cataract is reported in both age groups (3511/102,590 of ≤18 years and 187,314/478,876 of >18 years), but the prevalence is higher in the >18 years cohort reiterating that congenital form is rare compared to common age-related cataract. The same is observed with glaucoma as well (813 cases in ≤18 years and 25,485 cases in >18 years). Further, the prevalence of primary angle closure glaucoma (PACG) (2983 of the 25,485 (11.7%) glaucoma cases in >18 years age) is almost similar to primary open angle glaucoma (POAG) (2763/25,485 (10.8%)) in this cohort which is in accordance with the fact that prevalence of PACG is higher in Asians compared to Caucasians. The clinical data summary of the overall cohort is presented in Table 3.
OphthatomeTM contains 5,777 (0.99%) cases reporting family history of certain ophthalmic disease, 7,010 (1.20%) cases reporting a family history of systemic disease(s) and 186 cases (0.03%) reporting family history of both ophthalmic and systemic diseases. Figure 2E, 2F and 2G represents the details of systemic diseases of the family members (first or second degree relative or spouse), family history of ophthalmic diseases and disease diagnosis and family history of same disease, respectively in the 186 cases with family history of both systemic and ophthalmic diseases. Figure 2G shows that among all the common eye diseases, glaucoma and inherited retinal degenerations have a genetic component as expected.
Research and Clinical Applications of OphthatomeTM
Cohort selection
Complex diseases present with various analytic challenges, including lack of homogeneity in disease phenotype, variability in disease progression rate, response to drugs and disease outcome. Therefore, aggregation of clinical data from large patient cohorts are needed to identify common as well as divergent trends in disease progression. OphthatomeTM provides many strategies for patient selection through filters and Boolean searches with operators and modifiers. Selection of cohorts based on (i) demographics, (ii) disease type and subtype, (iii) quantitative traits like a) refractive error (myopia and hyperopia), b) intraocular pressure, c) central corneal thickness, (iv) number of visits (v) systemic diseases (vi) family history of ophthalmic and/or systemic diseases (vii) diagnostic procedural images (viii) visual field index values (ix) visual impairment status and (x) drugs prescribed, are available with the ability to build complex multiparametric searches.
A series of filters covering demography, clinical features and prescribed drugs can be applied in OphthatomeTM (Figure 3A) to select a cohort of patient samples (10,540 cases) as represented in Figure 3B). Such a large number of disease samples can be further narrowed using additional filters to create a near homogeneous cohort sharing specific disease phenotypes for clinical or genetic analysis, for example.
Cohort selection for deeper analysis
Few case studies are as presented here.
Glaucoma is a heterogeneous disease with multiple subtypes, and with a myriad of treatment options. To compare patient’s response to beta-blockers alone, or in combination with other anti-glaucoma medications, a combination of filters was used to select appropriate disease cohorts as shown in Figure 4. Glaucoma used as a disease type and ocular hypertension used as disease subtype, shortlists 26,298 (4.52% of the entire cohort) and 1904 cases (0.32%), respectively. Additional filters applied successively include, >1 visit – 1630 cases, high intraocular pressure – 1513 cases, drugs prescribed; cohort-A, beta blockers + other category of drugs – 363 cases, cohort-B, beta blockers + other anti-glaucoma medication (AGM) – 72 cases, and cohort-C, beta blockers alone – 33 cases. Availability of Humphrey visual field image for each of the three cohorts further narrowed the numbers as shown in Figure 4. The comprehensive clinical details of each patient can be extracted in a tabular format from the database and used for further analytics. Follow up data are available for a subset of patients under different treatment conditions and analysing cases with at least two VFI datapoints at ≥ one-year interval (Table 4) revealed number of cases that were stable and those progressed. For example, of the 9 individuals treated with beta blockers alone, 7 had stable VFI and 2 converted to primary angle closure (PAC) within 2 years. Additionally, of the 43 patients treated with beta blockers + AGM,11 cases were not further analysed as they were diagnosed with either POAG or secondary glaucoma in the first visit along with OHT. However, 29 of the remaining 32 treated patients had stable VFI for four years, one case converted to PAC and two individuals progressed to POAG, in 4 years. Cumulative data from drug responsive and non-responsive patient groups can be further investigated using molecular and genomic tools.
Drugs blocking growth of new blood vessels (neoangiogenesis) has improved vision dramatically in a large subset of patients with diabetic retinopathy and wet age-related macular degeneration (wet-AMD). OphthatomeTM has information of 5466 patients treated with anti-angiogenic therapy such as Avastin and Lucentis (Table 5). Follow up data on these individuals have identified drug resistance in a fraction of the treated patients opening opportunities to understand the mechanism of resistance (Unpublished data).
Seasonal allergen or seasonal changes show increased incidence of infectious or non-infectious conjunctivitis. OphthatomeTM has 12,594 cases of conjunctivitis and the subtype classification reveal 7414 cases of viral, 1604 bacterial and 912 allergic conjunctivitis. Analysing the time period of highest incidence of infection or allergy would reveal details of epidemiological trends in disease outbreak, the causative infective agent or the appearance of seasonal allergens that could be used for treatment and prophylactic disease management.