Melanie Campbell

Professor

Office: PHY 353
Phone: (519) 888-4567 ext. 36273
Email: mcampbel@uwaterloo.ca
Website: www.campbelllabs.uwaterloo.ca

Research interests

Optical properties of the eye, optical quality of ophthalmic instrumentation and optical design, refractive properties of the crystalline lens and their changes with growth and accommodation, retinal image quality, monochromatic aberrations of the eye, optical effects of refractive surgery, reflections from the retina, confocal microscopy and ophthalmoscopy, measurement of refractive error.

Present research activities

Analysis of the blur of the optical image on the retina and factors influencing this blur. Maintenance of image quality with growth and accommodation. Presbyopia. Changes in optical quality of the eye following refractive surgery (PRK). Influence of optical blur on ophthalmic instrument performance. Improved optical diagnostic and therapeutic ophthalmic instrumentation.

Of particular interest is the gradient of refractive index within the crystalline lens of the eye and efforts have concentrated both on measuring this distribution and on modeling the resulting optical quality of the lens and eye. Maintenance of optical image quality during growth and accommodative changes is being investigated. A sophisticated optical design program (Code V) is used to predict optical image quality on the surface of the retina corresponding to different locations in the visual field, and to investigate the influence of the pupil and of optical component tilt and decentration.

The blur on the retina of the human eye is being measured using psychophysical methods and an improved objective Hartmann-Shack technique. Monochromatic aberrations (spherical aberration and coma) and longitudinal and transverse chromatic aberrations are measured using novel techniques. The influence of pupil size and position and accommodative state on image quality is being investigated. Conditions for optimal image quality for the viewing of structures in the eye are being investigated and instrumentation developed both to indicate the optimum and to improve image quality.

Future measurements will investigate the optical quality of the crystalline lens with age and as the ciliary muscle contracts to focus at near and resulting changes in the eye's optical image quality. Assessment of the type and amount of aberration present will allow the separation of the contributions of the optical elements and the pupil to optical quality. This will simplify the analysis of changes in optical quality with changes in pupil size, accommodative state and age. The first anatomically-based lens and eye models which accurately predict measured optical performance are currently being developed. An improved technique for measuring the optical quality of the eye will be used to assess the comparative performance of uncorrected eyes and eyes corrected with spectacles, contact lenses and surgery.

The influence of the optical quality of the eye on ophthalmic instrumentation is being explored and methods of improving the resolution of the eye-instrument combinations continue to be developed (including the use of adaptive optics). A new high resolution confocal scanning laser microscope/ophthalmoscope has been constructed and is being used to explore changes in the structures at the rear of the eye in the healthy eye and early in disease progression.