The Loewenfeld Lecture


At the Pupil Colloquium in Mobile Alabama in 1997, Dr Thompson spoke up at the Business Meeting – in Dr Loewenfeld’s absence – to honor his teacher. He proposed that the group endorse a series of Lectures to be given at the Pupil Colloquium and called The Loewenfeld Lectures. This was warmly supported by the members, and Dr Thompson was surprised to find himself asked, on the spot, to be the first such lecturer.

Dr Irene Loewenfeld had planned to attend the 2001 Colloquium at the Asilomar Conference Centre in Pacific Grove, California, but 5 days before the meeting she developed a bad bronchitis and was unable to travel. Dr Thompson and Dr Larson had prepared a certificate for Dr Loewenfeld, nicely printed, gilt-edged and framed.

In her absence, the statement on the certificate was read out by Dr Thompson, signed by all in attendance, and sent to her by mail. The purpose of the statement was to affirm in writing the group’s support of the Loewenfeld Lecture series. It was worded as follows:

"In recognition of Dr. Irene Loewenfeld's distinguished scientific position in the physiology of the pupil, and in commemoration of her valuable services to The Pupil Colloquium - to which she has been a vigorous contributor since the first meeting in 1961, personally hosting the meeting on three separate occasions (1963, 1973 and 1991); the leaders of the Colloquium shall at each meeting, or periodically, nominate some person to deliver a lecture before the group, to be called "The Loewenfeld Lecture", which shall consist of a critical résumé of recent advances in knowledge of the pupil of the eye and its functioning, or of any related original investigation, and shall be delivered at the regular meeting of The Pupil Colloquium."


If this old-fashioned, all-in-one-breath summary of the founding of the Loewenfeld Lecture Series sounds familiar to an ophthalmic antiquary, it will be because it is copied in large part from a similar statement made by the Ophthalmic Society of the United Kingdom in 1883 when the Bowman Lecture series was founded.


First Loewenfeld Lecture (Nottingham, 1999)

H. Stanley Thompson, M.D.

Dr. Thompson started by reviewing the naming of the pupil of the eye, showing that the word used for the black spot in the center of the eye is a diminutive in many unrelated languages, and that it is generally agreed that this is because of the common human experience of seeing a minified reflection on the moist anterior surface of the eye. He then proceeded to review the history of the use of pupillary mobility in the clinical examination as an indicator of the amount of vision potential in a given eye. He offered an opinion as to why the examination of the pupil was not an invariable component of the routine eye examination during the 19th century.


Second Loewenfeld Lecture (Pacific Grove, California, 2001)

John L. Barbur, PhD "Learning from the pupil -studies of basic mechanisms and clinical applications"

The Second Loewenfeld Lecture reviewed findings from recent pupillometric studies in human subjects that reveal the existence of a number of different pupil response components. It is now well established that in addition to light flux changes, other stimulus attributes such as colour, spatial structure or movement can also cause a transient constriction of the pupil, even when the onset of the stimulus causes a net Use of uninitialized value in concatenation (.) or string at E:\listplex\SYSTEM\SCRIPTS\filearea.cgi line 455, line 48. decrease in light flux level on the retina. Pupil studies in patients with damage to specific areas of the brain suggest that the pupil response to light flux changes also involves more than one component. The rest of the lecture demonstrated the usefulness of pupil response components both in normal subjects and in groups of patients with selective loss of function as a result of damaged or abnormal visual pathways. A summary of the Second Loewenfeld Lecture and other related publications are available in pdf and can be downloaded from:


 Third Loewenfeld Lecture (Kolimpari, Crete, 2003)

Randy Kardon MD PhD "The Pupil Light Reflex in Disorders of the Visual Pathway"

Randy Kardon was mentored by H. Stanley Thompson throughout his clinical and research training at the University of Iowa and also benefited from many fruitful interactions with Dr. Loewenfeld at her home in Falmouth, Massachusetts on Cape Cod. Dr. Kardon, now Professor and Director of Neuro-ophthalmology, pointed out aspects of the afferent portion of the pupil light reflex pathway in disorders of the retina and optic nerve that have furnished new perspectives about how disease affects the input portion of the visual system. He and his colleagues have found that characterizing the pupil response as a function of intensity of the light (stimulus-response curves) revealed that disorders of the optic nerve usually produce more of a deficit at the high intensity side of the response curve compared to the opposite, normal eye of patients. He pointed out that while psychophysical tests of function such as visual field testing are threshold tests of function, the pupil light reflex reflects more of the visual system’s response to suprathreshold levels of light and disease can differentially affect these two ends of the visual response function. It was shown that this may relate to how disease affects the firing pattern of neurons, in terms of the amount of light needed to elicit any neuronal discharge vs. the extent of afferent neuronal discharge possible with maximal light stimulation.

The second part of the lecture called attention to new aspects of the afferent pupil light reflex pathway, namely the melanopsin retinal ganglion cells that have been found to project to the pretectal olivary nucleus in the midbrain (interneuron in the light reflex) as well as to the suprachiasmatic nucleus, where diurnal light rhythms are mediated. The melanopsin retinal ganglion cells receive input from rods and cones but also are capable of photo-excitation without photoreceptor input. These neurons respond in more of a direct current (DC) manner when excited on their own; their output summates the total light input and their firing is sustained. As this neuron is better elucidated, more of the mysteries about the pupil light reflex in relation to light input characteristics and the pupil response to diseases of the retina and optic nerve will be solved.


 Fourth Loewenfeld Lecture (New York, 2005)

To be announced