Allan F. Wiechmann

Contact Information:
Allan F. Wiechmann


Wiechmann, Allan F. (HSC)
Associate Professor

Department of:

College Of Medicine/Cell Biology -Associate Professor

Center of:


University of California   PhD  

Professional Interest/Expertise/Specializations:
The goal of our research is to advance our understanding of how circadian signals influence the health of ocular tissues, and to apply this knowledge to the treatment of human ocular disease. We have identified receptors for the circadian signaling molecule, melatonin in the retina and other ocular tissues, notably the sclera, ciliary epithelium, choroid, and corneal epithelium. We are attempting to identify the neurons of the inner retina that respond to nocturnal melatonin to alter the sensitivity of the retina to environmental light. This knowledge will give us a better understanding about how circadian rhythms affect retinal dark adaptation and sensitivity to light. The surface of the corneal epithelium is a unique stratified epithelium that provides a crucial barrier to ocular infection, and has a major role in the maintenance of corneal transparency and homeostasis. The daily balance of corneal surface epithelium maturation and desquamation is a critical factor in maintaining the integrity of the barrier function. The intercellular junctions that comprise the barrier in the surface layer of cells must be actively disrupted on a daily basis to enable the surface cells to be shed as part of a renewal process, and the underlying layer of cells must then quickly form new intercellular junctions to maintain the integrity of the protective barrier. We have suggested that circadian signals, mediated via activation of melatonin receptors on the corneal epithelium, orchestrate the temporal sequence of activities required for the daily shedding and maturation of the surface cells. We are employing a variety of molecular and cellular approaches to investigate the mechanisms by which junctional barriers are degraded and re-established on a daily basis. These studies may help to develop new therapeutic strategies to enhance barrier function of corneas recovering from injury or disease.


Research Projects:

Selected Publications:

Melatonin receptor expression in Xenopus laevis surface corneal epithelium: Diurnal rhythm of lateral membrane localization.
2009    Wiechmann AF, Hollaway LR and Summers Rada JA
Mol Vision
Circadian rhythms in the eye: The physiological significance of melatonin receptors in ocular tissues.
2008    Wiechmann AF and Summers JA
Prog Ret Eye Res
Influence of dietary melatonin on photoreceptor survival in the rat retina: An ocular toxicity study.
2008    Wiechmann AF, Chignell CF and Roberts JE
Exp Eye Res
Melatonin receptors in chick ocular tissues: Implications for a role of melatonin in ocular growth regulation.
2006    Summers Rada JA and Wiechmann AF
Invest Opthalmol Vis Sci
Localization of Mel1b melatonin receptor-like immunoreactivity in ocular tissues of Xenopus laevis.
2004    Wiechmann AF, Udin SB and Summers Rada JA
Exp Eye Res