Raymond P. Najjar

Dr. Raymond P. Najjar

Singapore Eye Research Institute/Duke-NUS Medical School, Singapore
orcid

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 April 2020 in New England Journal of Medicine
Verified
Journal Article
Closed access
DMDan Milea
Dan Milea
Raymond P. NajjarRaymond P. Najjar
Raymond P. Najjar
ZJZhubo Jiang
Zhubo Jiang
DTDaniel Ting
Daniel Ting
CVCaroline Vasseneix
Caroline Vasseneix
VBValérie Biousse
Valérie Biousse
Nonophthalmologist physicians do not confidently perform direct ophthalmoscopy. The use of artificial intelligence to detect papilledema and other optic-disk abnormalities from fundus photographs has not been well studied.

31 January 2024 in Journal of Physiological Anthropology
Verified
Journal Article
Open access
PDF file
SBSayantan Biswas
Sayantan Biswas
AKAntonio El Kareh
Antonio El Kareh
MQMariyem Qureshi
Mariyem Qureshi
DLDeborah Mei Xuan Lee
Deborah Mei Xuan Lee
CSChen-Hsin Sun
Chen-Hsin Sun
Raymond P. NajjarRaymond P. Najjar
Raymond P. Najjar
Background: Myopia, commonly known as near-sightedness, has emerged as a global epidemic, impacting almost one in three individuals across the world. The increasing prevalence of myopia during early childhood has heightened the risk of developing high myopia and related sight-threatening eye conditions in adulthood. This surge in myopia rates, occurring within a relatively stable genetic framework, underscores the profound influence of environmental and lifestyle factors on this condition. In this comprehensive narrative review, we shed light on both established and potential environmental and lifestyle contributors that affect the development and progression of myopia. Main body: Epidemiological and interventional research has consistently revealed a compelling connection between increased outdoor time and a decreased risk of myopia in children. This protective effect may primarily be attributed to exposure to the characteristics of natural light (i.e., sunlight) and the release of retinal dopamine. Conversely, irrespective of outdoor time, excessive engagement in near work can further worsen the onset of myopia. While the exact mechanisms behind this exacerbation are not fully comprehended, it appears to involve shifts in relative peripheral refraction, the overstimulation of accommodation, or a complex interplay of these factors, leading to issues like retinal image defocus, blur, and chromatic aberration. Other potential factors like the spatial frequency of the visual environment, circadian rhythm, sleep, nutrition, smoking, socio-economic status, and education have debatable independent influences on myopia development. Conclusion: The environment exerts a significant influence on the development and progression of myopia. Improving the modifiable key environmental predictors like time spent outdoors and engagement in near work can prevent or slow the progression of myopia. The intricate connections between lifestyle and environmental factors often obscure research findings, making it challenging to disentangle their individual effects. This complexity underscores the necessity for prospective studies that employ objective assessments, such as quantifying light exposure and near work, among others. These studies are crucial for gaining a more comprehensive understanding of how various environmental factors can be modified to prevent or slow the progression of myopia.

29 January 2019 in Journal of Pineal Research
Verified
Journal Article
Closed access
PDF file
APAbhishek S. Prayag
Abhishek S. Prayag
Raymond P. NajjarRaymond P. Najjar
Raymond P. Najjar
Claude GronfierClaude Gronfier
Claude Gronfier

23 January 2014 in PLOS ONE
Verified
Journal Article
Open access
PDF file
Raymond P. NajjarRaymond P. Najjar
Raymond P. Najjar
CCChristophe Chiquet
Christophe Chiquet
PTPetteri Teikari
Petteri Teikari
PCPierre-Loïc Cornut
Pierre-Loïc Cornut
BCBruno Claustrat
Bruno Claustrat
Claude GronfierClaude Gronfier
Claude Gronfier
The deterioration of sleep in the older population is a prevalent feature that contributes to a decrease in quality of life. Inappropriate entrainment of the circadian clock by light is considered to contribute to the alteration of sleep structure and circadian rhythms in the elderly. The present study investigates the effects of aging on non-visual spectral sensitivity to light and tests the hypothesis that circadian disturbances are related to a decreased light transmittance. In a within-subject design, eight aged and five young subjects were exposed at night to 60 minute monochromatic light stimulations at 9 different wavelengths (420–620 nm). Individual sensitivity spectra were derived from measures of melatonin suppression. Lens density was assessed using a validated psychophysical technique. Although lens transmittance was decreased for short wavelength light in the older participants, melatonin suppression was not reduced. Peak of non-visual sensitivity was, however, shifted to longer wavelengths in the aged participants (494 nm) compared to young (484 nm). Our results indicate that increased lens filtering does not necessarily lead to a decreased non-visual sensitivity to light. The lack of age-related decrease in non-visual sensitivity to light may involve as yet undefined adaptive mechanisms.

12 April 2019 in Frontiers in Neurology
Verified
Journal Article
Open access
PDF file
PCPratik S. Chougule
Pratik S. Chougule
Raymond P. NajjarRaymond P. Najjar
Raymond P. Najjar
MFMaxwell Finkelstein
Maxwell Finkelstein
NKNagaendran Kandiah
Nagaendran Kandiah
DMDan Milea
Dan Milea
The impact of Alzheimer's disease (AD) on the pupillary light response (PLR) is controversial, being dependent on the stage of the disease and on the experimental pupillometric protocols. The main hypothesis driving pupillometry research in AD is based on the concept that the AD-related neurodegeneration affects both the parasympathetic and the sympathetic arms of the PLR (cholinergic and noradrenergic theory), combined with additional alterations of the afferent limb, involving the melanopsin expressing retinal ganglion cells (mRGCs), subserving the PLR. Only a few studies have evaluated the value of pupillometry as a potential biomarker in AD, providing various results compatible with parasympathetic dysfunction, displaying increased latency of pupillary constriction to light, decreased constriction amplitude, faster redilation after light offset, decreased maximum velocity of constriction (MCV) and maximum constriction acceleration (MCA) compared to controls. Decreased MCV and MCA appeared to be the most accurate of all PLR parameters allowing differentiation between AD and healthy controls while increased post-illumination pupillary response was the most consistent feature, however, these results could not be replicated by more recent studies, focusing on early and pre-clinical stages of the disease. Whether static or dynamic pupillometry yields useful biomarkers for AD screening or diagnosis remains unclear. In this review, we synopsize the current knowledge on pupillometric features in AD and other neurodegenerative diseases, and discuss potential roles of pupillometry in AD detection, diagnosis and monitoring, alone or in combination with additional biomarkers.

1 November 2012 in Journal of Neuroscience Methods
Verified
Journal Article
Closed access
PTPetteri Teikari
Petteri Teikari
Raymond P. NajjarRaymond P. Najjar
Raymond P. Najjar
HMHemi Malkki
Hemi Malkki
KKKenneth Knoblauch
Kenneth Knoblauch
DDDominique Dumortier
Dominique Dumortier
HCHoward M. Cooper
Howard M. Cooper