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Making Contact

the spectral sensitivity of the melanopsin RETINAL/OPTIC NERVE HEAD DISEASES
pigment are being investigated as Objective pupillometry is providing useful
direct biomarkers of ipRGC function in information about the rod, cone, and
conditions such as mild traumatic brain ipRGCs furnishing the PLR for the early
injuries, amblyopia and glaucoma.
detection of retinal and optic nerve diseases.
TRAUMATIC BRAIN INJURIES In 16 patients with glaucoma, Kankipati
For functional optometrists, the assessment et al. showed there was a significant
of an alpha-omega pupil (AO pupil) is decrease in the ipRGC-mediated sustained
important in determining how the ANS is pupillary constriction when compared to
functioning at a particular time. In head age-matched controls with a correlated
and/or brain stem injuries, the sympathetic decrease with increasing glaucoma severity.
nervous system is often seen to dominate Research by Naijar et al. using chromatic
the parasympathetic nervous system, pupillometry showed deficits in pupillary
causing pupil dilation where the pupil is responses to blue light in patients with
unable to sustain constriction when a light early functional loss from glaucoma and
source is directly and continuously shone to red light in patients with late glaucoma
at it. The AO pupil reaction is graded compared with the control group. Even
by the speed/time and amplitude of the
pupillary release that occurs and is members of the Institute of Electrical and
indicative of adrenal fatigue or poor Electronics Engineers (IEEE), comprising
adrenal function. engineers and ophthalmologists, showed
Companies such as BrightLamp’s iPhone the potential of using PLR as a biomarker
in their statistically significant difference
app Reflex are assisting clinicians in the pupillary complexity between
with “objective” dynamic pupillometry glaucoma patients and healthy controls.
recordings of the PLR, pupil function
and the integrity of the midbrain. The They used their novel AI-powered test
diagnostic technology is quantifiable and with infrared sensors that monitored eye
can be standardized to provide reproducible movement and showed risk of glaucoma in
results in pupillary function parameters, just 10 seconds.
such as maximum/minimum diameter, As shown above, the eye-brain connection
constriction latency/amplitude, and is undeniable and any injuries to the
average/maximum constriction/dilation brain and its pathways are associated with
velocity. variability in pupil responses in the PLR.

AMBLYOPIA Dynamic pupillometry can have many
RAPD is difficult to measure reliably in clinical applications. Since there is no
subjective interpretation, it is useful in
patients with amblyopia. Since amblyopia the detection, diagnosis and management
has cortical aetiologies, Law et al. used the
binocular infrared pupillometer, RAPDx, of all neurological functions. It can also
from Konan Medical. Proposed RAPD provide information about imbalances in
can be elicited from this population with the ANS and a person’s overall well-being.
appropriately selected, cortex-mediated Advances in pupil analysis technology
parameters, such as small, low-contrast using objective, dynamic pupillometry
stimuli, rather than full field stimulation. are here, allowing clinicians to quantify a
The cortical information will not only be basic physiological reaction to metrics that
diagnostic but also prognostic as to who are reproducible and that can be used as a
will be most successful in therapy. valuable biomarker of brain function. l
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1- Law CL, Siu M, Modica P, Backus B. Stimulus characteristics affect assessment of pupil defects in amblyopia. Optom Vis Sci 2015; 92(5): 551-8
2- Kankipati L, Girkin CA, Gamlin PD. The post-illumination purple response is reduced in glaucoma patients. Invest Ophthalmol Vis Sci 2011; 52(5): 2287-92
3- Najjar RP, Sharma S, Atalay E, Rukmini AV, Sun C, Lock JZ, et al. Pupillary responses to full-field chromatic stimuli are reduced in patients with early-stage primary open-angle
glaucoma. Ophthalmology 2018; 125:1362–71
4- Ngo QC, Bhowmik S, Sarossy M, Kumar DK. Pupillary complexity for the screening of glaucoma. IEEE Access (DOI: 10.1109/ACCESS.2021.3122079)

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