Peripheral Choroidal Layer Response

Inclusion Criteria: A person is eligible for inclusion in the study if he/she: * Is between the ages of 18 and 40 yrs old * Has normal best corrected visual acuity being 20/20 or better * Has spherical refractive error between +1.00D and -6.00D. * Is capable of fixating on the target. * Has no prior ocular surgery. * Has no ocular pathology except keratoconus. * Can tolerate dilating eye drops Exclusion Criteria: A person will be excluded from the study if he/she: * Does not fall within above mentioned age group. * Has chronic or systemic eye disease that would interfere with pupil dilation via eye drops. * Underwent ocular surgeries or history of ocular trauma * Has shallow anterior chamber angle and/or glaucoma. * Has clinically significant dry eye. * Has signs of any choroidal or retinal pathology, and abnormalities in the visual pathway * Has spherical refractive error that exceeds the limits outlined above. * Has binocular anomalies (e.g. convergence insufficiency, strabismus, pseudo-myopia, amblyopia). * Is an adult unable to consent * Is an individual who is not yet adult (infants, children, teenagers) * Is a pregnant woman * Is a prisoner * Is a student for whom you have direct access to/influence on grades * Is an economically and/or educationally disadvantaged person