Artificial intelligence in diabetic retinopathy: A natural step to the future

Artificial intelligence in diabetic retinopathy: A natural step to the future

Use of artificial intelligence in medicine in an evolving technology which holds promise for mass screening and perhaps may even help in establishing an accurate diagnosis. The ability of complex computing is to perform pattern recognition by creating complex relationships based on input data and then comparing it with performance standards is a big step. Diabetic retinopathy is an ever-increasing problem. Early screening and timely treatment of the same can reduce the burden of sight threatening retinopathy. Any tool which can aid in quick screening of this disorder and minimize requirement of trained human resource for the same would probably be a boon for patients and ophthalmologists. In this review we discuss the current status of use of artificial intelligence in diabetic retinopathy and few other common retinal disorders.

Artificial intelligence (AI), has emerged as a major frontier in computer science research. Healthcare affordability, quality, and accessibility can be amplified using this technology. AI in simple words means to accomplish a task mainly by a computer or a robot, with minimal involvement of human beings. In other words, AI is simulation of human intelligence by a software/machine. It is essentially the ability of a computerized system to show cognitive abilities. Just like learning in humans, the AI systems need to be exposed to a database which allow them to first “learn” simple targets with regards to a dedicated finding or disease.

However, AI is much more than simply a humongous database. Following initial steps of learning, the system or machine is then taught to “improve”, i.e., evolve upon its initial learning to become more accurate and efficient. This learning is further compounded by use of complex mathematical equations for the system to understand nonlinear relationships between different variables through an information flow referred to as “neural networks.” In essence, this form of “higher training” allows AI to judge and weigh possibilities of different outcomes, much like an ideal physician! Many of these technological advances are in part due to software that have now been made available by resources related to information and technology. An example of commercially available machine learning software is Scikit-learn which require computer languages like Python as a platform for working. Scikit learn is a machine learning library for use in python programming language and it has been used for diabetic retinopathy detection. Several commercial software currently integrates artificial Intelligence and machine Learning for fundus image processing and evaluation. Fundus evaluation software are being made as student projects in several engineering colleges for the past few years. Open Indirect Ophthalmoscope by LVPEI and MIT has an inbuilt option for DR detection by Machine Learning. Also, Kavya Kopparapu's Eyagnosis app, which along with a 3D printed smartphone fundus camera, were developed in 2016 and tested in several leading eye hospitals.

AI-assisted medical screening and diagnosis based on images are currently evolving. Application of this technology in ophthalmology is currently focused mainly on the diseases with a high incidence, such as diabetic retinopathy (DR), age-related macular degeneration

(ARMD), glaucoma, retinopathy of prematurity (ROP), age-related or congenital cataract, and retinal vein occlusion (RVO). DR is an eye disease known to cause moderate to severe visual loss and is the leading cause of blindness in working-age people suffering with long standing diabetes. The health burden is accentuated by the huge per capita cost. This has further increased since the introduction of anti VEGF agents. Very often the disease does not show overt symptoms until it reaches an advanced stage; however, if detected early on, vision impairment can be averted by early intervention which is also the most cost-effective option. In view of the alarming increase in the number of people with diabetes and dearth of trained retinal specialists and ophthalmologists, a computer-based analysis of the fundus images by an automated approach would lessen the burden of the health systems in screening for DR and offer a near ideal system for its management. Therefore, screening will be valuable at an stage of the disease and will also be helpful in avoiding blindness among 90% patients.

We searched all the English language studies relative to ophthalmology published on m PubMed and springer database. The articles published in last 10 years that we deemed relevant were summarised. The keywords used for the PubMed search were artificial intelligence, ophthalmology, deep learning, machine learning, diabetic retinopathy.

The Problem

Regardless of the type of diabetes, all individuals diagnosed with DM need regular and repetitive annual retinal screening for timely detection and apt treatment of diabetic retinopathy (DR). Conventionally, retinopathy screening is done by fundus examination by ophthalmologists or with the help of color fundus photography using conventional fundus cameras (mydriatic or non-mydriatic) by trained eye technicians or optometrists. The primary

issue is the grading of the retinal images by ophthalmologists (retinal specialists) or trained persons, whose numbers are very scarce compared to the load of patients requiring screening.

Second, some of these patients are based in rural areas and can’t visit an eye care provider. Thirdly, as such follow ups are required for years together, the attitude, and/or behavioral aspects negatively impact the patients practice despite knowledge of consequences. These issues can be solved with provision of an automated imaging system within easy reach of the patient. Hence, there has been an increasing interest in the development of automated analysis software using computer machine learning/artificial intelligence (AI) for analysis of retinal images in people with diabetes thus solving at least some part of the problem.

The Solution: Principle Behind Artificial Intelligence

It is basically a process of teaching a machine to recognize specific patterns. Historically, it has been used for various technical tasks including accurate classification of high-resolution images. The techniques of AI devices largely classified into following major categorie-the machine learning techniques, the natural language processing methods, speech, vision, expert system, robotics etc. So far, the machine learning techniques are more utilized in ophthalmology.

Machine learning process mainly include two parts, training set followed by validation set. This process occurs by providing large number of training data i.e., thousands of retinal images of varying grades of DR to the machine/system as the training set Most of the data are labeled as per features in advance by the authoritative professionals. After being exposed to numerous annotated retinal images the machine learns to grade DR by itself by building a model of complex relationships between input data and generalizing a performance standard.

In addition, some other data are used to verify the established algorithm i.e., validation set

Downsides of AI

In view of below 90% sensitivity and specificity of the device, 1 in 10 patients theoretically may have a false-positive and false negative result. So, it is not absolutely fail-safe. Thus, it is crucial to educate patients and doctors that the present generation devices are not 100% reliable. A false negative result may provide a pseudo sense of security about the retinopathy status. For the present, a comprehensive dilated eye examination remains the gold standard of screening and cannot be replaced with this device till appropriately proved otherwise.

Diabetes has numerous ocular manifestations other than DR, which includes glaucoma, age-related macular degeneration (ARMD), cataract, dry eye. A comprehensive examination isobligatory for proper diagnosis and management in these patients

Diabetic macular oedema is the leading cause of vision loss in patients with diabetes. Stereoscopic macular examination coupled with optical coherence tomography remains the gold standard for diagnosing this condition. Though all subjects with ETDRS level 43 or higher DR were detected via IDx-DR, but many cases of subtle DME were missed because of non-addressal. Legal accountability in cases of misdiagnosis with artificial intelligence is another subject that is yet to be fixed.

Uses of Artificial Intelligence in Other Ophthalmic Conditions

Age-related macular degeneration

ARMD is a chronic and irreversible macular disease and one of the leading causes of central vision loss in people aged over 50 years With the demand of a regular screening in such a condition, an automatic AMD diagnosis tool may clearly reduce the work load of clinicians. Few studies used fundus image as the input, where other existing researchers have used OCT as a tool for deep learning of ARMD. Bogunovic et al. employ an algorithm to predict anti- VEGF treatment needs from OCT scans taken during treatment initiation.

Retinal vein occlusion

A research group utilized CNN combined with patch and image-based vote methods to recognize the fundus image of branch retinal vein occlusion (BRVO) automatically. They reported a high accuracy over 97%.

Retinopathy of prematurity

ROP is a leading cause of treatable childhood blindness when diagnosed timely. This disease demands repeated follow up and screening, which is very tedious and demanding. So, application of AI in ROP screening may expand the proficiency in ROP care. Promising results have been obtained from various studies. Most of them are presently based on two- level sorting (plus or not plus disease).

Anterior segment diseases

The disease mainly includes cataract and glaucoma which are very prevalent conditions in community health care. Automated grading of nuclear cataracts using slit lamp has been reported. The detection of glaucom mainly depends on the intraocular pressure (IOP), thickness of retinal nerve fiber (RNFL), optic nerve, and visual field examination. Unlike diabetic retinopathy, glaucoma is not an imaging disease. Thus, the hurdle would be to incorporate other results tests such as OCT images, IOP, disc photos, and longitudinal visual field data into AI systems. Hwang . have combined corneal data from slit-scan tomography and spectral-domain OCT in a method for screening corneas for very early signs of keratoconus using artificial intelligence.

Legal Aspects of AI

AI has tremendous potential to reshape health care and it is more rapidly to do so. But the legal issues involved with the development and implementation of AI algorithms are considerable. Regulation, legal causes of action such as medical malpractice and product liability, intellectual property, and patient privacy all have real implications for the way AI is developed and deployed. When it comes to AI and machine learning, there are currently more legal questions than answers. How can AI systems ensure consent? How will questions of liability be addressed? How does AI fit into existing ethical frameworks in India? How can the security and accuracy of AI solutions be ensured—particularly in the health sector as individual lives can be at stake and highly sensitive data is being handled? These are few questions that are still to be answered.

Future Outlook

Use of AI in medical diagnostics, especially in ophthalmology heralds a new era. If proven to be sensitive and specific enough this technology can totally change the way we look at screening programs and community-based ophthalmology programs. Most of the present systems use conventional of 30–50° fundus images. Perhaps applications based on wide field imaging and OCT angiography based vascular analysis might yield even more consistent results. However, the high cost of wide field imaging and OCT angiography may be a limiting factor for this at present. A lot of work is also being done on identifying serum biomarkers for early detection and monitoring of diseases like diabetic retinopathy. Thus, a comprehensive analysis of ocular imaging, systemic parameter profile and other serumbiomarkers using AI might provide better insights, perhaps even better conclusions than what human intelligence is capable of deriving.