The Bull's Eye Pattern of the Tear Film in Humans during Visual Fixation on En-Face Optical Coherence Tomography. 2019

Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
From the San Giovanni di Dio hospital, Clinica Oculistica, Azienda Ospedaliera Universitaria di Cagliari, Cagliari, Italy. pietronapoli@ymail.com.

The aim of the study was to define and characterize the optical behavior of the tear film during visual fixation in humans on en-face optical coherence tomography (OCT). We included 20 healthy participants, 60% female, aged from 25 to 42 years (33.05 ± 4.97 [mean ± SD]) and ten patients with severe dry eye, 50% female, aged from 26 to 42 years (33.7 ± 5.31). To perform high-resolution tear film imaging, participants were asked to gaze at the internal fixation point in the spectral-domain anterior segment OCT device, and meanwhile scanning session was executed at the following time-points after blinking: at the 2nd, 3rd, 4th, 5th, and 6th second. After one hour, OCT imaging was repeated (second session) by a different operator masked to the study to verify the reliability of results. During each measuring session, a pulse oximetry was used for continuously measuring the heart rate and oxygen saturation (SpO2%). A preliminary experiment was also performed to test the absence of geometric patterns from the anterior surface of a motionless artificial eye. OCT imaging showed a motionless, stable anterior surface of the artificial eye and in dry eye patients. Conversely, in the healthy participants of the study, a bull's eye pattern of the tear film was detected by OCT at the 2nd, 3rd, 4th, 5th, and 6th second after blinking, respectively, in 45%, 60%, 45%, 60%, and 40% of OCT scans during the first session, and in 35%, 65%, 65%, 60%, and 35% of cases in the second session. Overall, a total of 200 OCT scans were performed in normal human population. A significant correlation was found between the novel tear film pattern and heart rate during the first and the second session (p < 0.01) in healthy eyes. Conversely, no correlation was revealed with SpO2%. Intraclass correlation (ICC) analysis for OCT imaging of the tear film revealed a statistically significant reproducibility of the results (ICC = 0.838; p < 0.01), indicating the high level of reliability of the method, independently of heart rate and SpO2% variables. There exists a novel, geometric pattern of the tear film during visual fixation detectable by en-face OCT, which is mainly evident as heart rate increases. Its discovery implies in turn the presence of a specific vibration (or imperceptible motion) of the tear film that, at present, is not recognized and corrected by the OCT software (in image postprocessing) unlike other eyeball movements.

UI MeSH Term Description Entries
D008297 Male Males
D010108 Oxyhemoglobins A compound formed by the combination of hemoglobin and oxygen. It is a complex in which the oxygen is bound directly to the iron without causing a change from the ferrous to the ferric state. Oxycobalt Hemoglobin,Oxycobalthemoglobin,Oxyhemoglobin,Hemoglobin, Oxycobalt
D001767 Blinking Brief closing of the eyelids by involuntary normal periodic closing, as a protective measure, or by voluntary action. Orbicularis Oculi Reflex,Reflex, Blink,Reflex, Corneal,Reflex, Orbicularis Oculi,Winking,Blink Reflexes,Corneal Reflexes,Orbicularis Oculi Reflexes,Blink Reflex,Reflexes, Blink,Reflexes, Orbicularis Oculi
D003315 Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed) Corneas
D005260 Female Females
D005403 Fixation, Ocular Positioning and accommodation of eyes that allows the image to be brought into place on the FOVEA CENTRALIS of each eye. Focusing, Ocular,Ocular Fixation,Eye Gaze,Eye Gazes,Gaze, Eye,Gazes, Eye,Ocular Focusing
D006339 Heart Rate The number of times the HEART VENTRICLES contract per unit of time, usually per minute. Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328 Adult A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available. Adults
D000869 Anterior Eye Segment The front third of the eyeball that includes the structures between the front surface of the cornea and the front of the VITREOUS BODY. Anterior Eye Segments,Eye Segment, Anterior,Eye Segments, Anterior,Segment, Anterior Eye,Segments, Anterior Eye

Related Publications

Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
June 2006, Optics letters,
Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
February 2019, Biomedical optics express,
Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
April 2023, Cornea,
Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
July 2012, Eye & contact lens,
Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
February 2006, Retina (Philadelphia, Pa.),
Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
April 2014, Biomedical optics express,
Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
October 2017, Ophthalmology,
Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
December 2016, JAMA ophthalmology,
Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
September 2015, Ophthalmology,
Pietro Emanuele Napoli, and Matteo Nioi, and Ernesto d'Aloja, and Maurizio Fossarello
September 2019, Indian journal of ophthalmology,
Copied contents to your clipboard!