Karan trained in Ophthalmic Techniques (Medical Optometry) at the All India Institute of Medical Sciences (RP Centre), where he learned ocular anatomy and physiology, geometric and visual optics, microbiology, biochemistry, pathology, pharmacology, clinical ocular diagnostics and electrophysiology. He learned and practiced the art of objective and subjective clinical refraction, spectacle dispensing, contact lens fitting, and evaluation and management of disorders of eye position (squint/ strabismus), motility (esotropia, exotropia, latent deviations), and visual deprivation (amblyopia from congenital cataract, anisometropia, strabismus, nystagmus). Faculty instructors emphasized comprehensive history taking prior to clinical examination, with support from laboratory techniques. Assignments in eye bank (e.g. corneal button tissue excision and preservation), urgent ocular casualties (e.g. UV exposure from a welding torch), surgical methods (e.g. cryo-ablation), and rural community camps (cataract, trachoma, corneal xerosis) were included.

Karan passed the Optometry Admission Test and moved to New York in September, 1989; to work in a private Contact Lens Specialty practice (Dr Barry Farkas). He taught Visual Optics and demonstration labs in skaiscopy/retinoscopy for refracting schematic eyes with simulated astigmatism at NYC Technical College (Brooklyn) to licensed opticians, while helping develop protocols for Helen Keller International: during the tenure of Dr. Jordan Kassalow. Following a pre-requisite class in Statistics at Hunter College (CUNY), Karan enrolled in the Graduate Program in Vision Science at the State University of New York, College of Optometry. Because funding from Albany was scarce, Karan certified to refract and dispense contact lenses and spectacle (ABO/ National Contact Lens Examiners). As ophthalmic technician at the New York Eye and Ear Infirmary (Oct 1990 to August 1996), he was certified for tests required for the Ocular Hypertension Treatment Study (OHTS), and to test visual acuity using the ETDRS protocols. Karan was influenced by the prolific publication record and international prominence of Dr Robert Ritch, while serving on his team part time to help manage eye examinations (glaucoma) for about 5 patients every hour.

On recommendation by Professor Angela Brown (Infant Color Vision), Karan chose Dr. Philip B. Kruger as primary mentor and attended discussions on unsolved problems in accommodative control theory. Courses in geometric optics (Milton Katz), Visual Perception (Hal Sedgwick), Monocular Sensory Process (Al Lewis), Optics of the Eye (PB Kruger), Ocular Anatomy & Physiology (Harry Wyatt, Vesna Sutija) and Control Systems (Mark Rosenfield, Kenneth Ciuffreda, Jordan Pola) provided background for understanding the domain of stimuli and control of ocular accommodation (eye focus adjustment). To help design experimental protocols, the statistical methods discussed with Sheldon Ebenholtz and Beth Davis proved essential. The National Eye Institute, National Institutes of Health, Bethesda, Maryland, provided a post-doctoral fellowship (F-32 National Research Service Award) based on equivalence (International Consultants of Delaware) with the US Doctor of Optometry; approval of the application contingent on review by a committee of a proposal to test a scientific hypothesis of clinical significance, backed by credible evidence and preliminary pilot data. The experimental design, feasibility and scientific significance of the proposal, reviewed by the Behavioral Neuroscience Study Section of the NIH, was approved and funded at $93,600 remitted to the Research Foundation of SUNY.

Studies from Dr. Kruger's laboratory at SUNY were published in peer-reviewed journal articles indexed on Pub-Med (NLM.GOV), in book chapters such as Adler's Physiology of the Eye (Adrian Glasser, Accommodation: Elsevier, 2011). The research employed the methods described in Campbell and Robson (1959), and Westheimer (1966); aiming to provide support for and confirm the hypothesis of retinal control of eye focusing by analysis of chromatic fringes (Fincham, 1951), and to discredit a mistaken point of view (Troelstra, Zuber, et al 1964), thereby revising the trial and error hypothesis popular among engineers of the day (50 percent wrong response on sudden random presentation of step change in lens power). From 1984 onward, Dr Kruger’s lab, and others (e.g. Dr Lawrence R Stark, Dr Frances Rucker, Dr Yinan Wang) have continued along extensions of the empirical and theoretical foundations explicated by Kruger. By 2006 it was established that the blur feedback model of Troelstra, et al (1964) needs to include intrinsic directional cues (e.g. contrast comparison between spectral bands) operating without feedback (stabilized ocular focus/ open loop by electro-optical compensation of retinal defocus at high temporal frequency), with consequences for eye growth mechanisms driving onset of myopia in children and advancing near-sightedness in teenage years. The poly-chromatic optical image at the retina and analysis of the spatial and temporal properties of the ambient optic array (JJ Gibson) continue to be active domains of investigation.

Dr. Aggarwala is presently developing a grant application for better ocular diagnostics of eye pressure based on a recently published synthesis (January 2020) that provides evidence for a hypothesis experimentally tested in years 1994 to 1996 with the assistance of physicist Ronald H Silverman at Cornell Ophthalmology (Coleman Lab, relocated to Columbia) based on experimental protocols imaging the anterior ocular tissue during accommodation. These images of changes in ocular anatomy from a behavioral task, were presented at the annual meeting of the Association for Research in Vision and Ophthalmology (ARVO, 1996), and provide strong evidence that habitual focusing distress can elevate intra-ocular pressure (IOP), predisposing the individual to onset and progression of myopia, glaucoma, and detachment of the peripheral retina. The stress of the eye focusing muscle will be quantifiable by measuring eye pressure at rapidly cycled intervals.

Aside from ocular diagnostic application development, Dr Aggarwala cherishes poetry (e.g. Frost), art (e.g. Vermeer), music (e.g. Josh Groban, Judy Collins, James Blunt) and bio-diverse forested parks with a lake or stream.