Influence of the tear film on optical quality of the eye

doi:10.1016/S1367-0484(97)80011-2

Contact Lens and Anterior Eye

Volume 20, Issue 4, 1997, Pages 129-135

https://doi.org/10.1016/S1367-0484(97)80011-2 Get rights and content

Abstract

The optical quality of the tear film of the eye was tested by measuring the retinal image before and after the break-up time (BUT). An objective method was used based on the evaluation of the retinal image of a point test projected onto the fovea. The loss of an entire tear film would result in a decrease in the optical quality because of corneal irregularities and the formation of an irregular tear lens after the BUT. Our results confirm the expected loss both of non-contact lens wearers and contact lens wearers. Also, the fact that the optical deterioration found after the BUT is greater for contact lens wearers confirms that soft contact lens wear produces a disruption of the tears.

References (42)

SorensenT. et al.
Tear flow in normal human eyes. Determination by means of radioisotope and gamma camera
Acta Ophthalmol.
(1979)
SharmaA. et al.
Mechanism of tear film rupture and its implications for contact len wear tolerance
Am. J. Optom. Physiol. Opt.
(1985)
MengherL.S. et al.
Effect of fluorescein instillation on the pre corneal tear film stability
Curr. Eye Res.
(1985)
HoldenB.A.
The Glenn A. Fry Award Lecture 1988. The ocular response to contact lens wear
Optom. Vis. Sci.
(1989)
CraigJ.P. et al.
Tear lipid layer structure and stability following expression of the Meibomian glands
Ophthal. Physiol. Opt.
(1995)
GuillonJ.P. et al.
Corneal desiccation staining with hydrogel lenses: tear film and contact lens factors
Ophthal. Physiol. Opt.
(1990)
Weil B.A. and Milder B. The lachrymal system, Appleton Century Crofts, Norwalk, CT,...
RubenM. et al.
Contact Lens Practice
RubenM. et al.
Contact Lens Practice
CarneyL.G. et al.
Buffering in human tears: pH responses to acid and base challenge
Invest. Ophthalmol. Vis. Sci.
(1989)
CraigJ.P. et al.
Effect of age on tear osmolality
Optom. Vis. Sci.
(1995)

CraigJ.P. et al.

Refractive index and osmolality of human tears

Optom. Vis. Sci.

(1955)

MishimaS. et al.

Determination of tear volume and tear flow

Invest. Ophthalmol. Vis. Sci.

(1996)

TsubotaK. et al.

Tear evaporation from the ocular surface

Invest. Ophthalmol. Vis. Sci.

(1992)

MathersW.D. et al.

Tear flow and evaporation in patients with and without dry eye

Ophthalmology

(1996)

TiffanyJ.M.

The viscosity of human tears

Int. Ophthalmol.

(1991)

MauriceD.

The Charles Prentice award lecture 1989. The physiology of tears

Optom. Vis. Sci.

(1990)

LinsenC. et al.

Physiology of the lacrimal system

Bull. Soc. Belge Ophthalmol.

(1990)

Van HaeringenM.J.

Clinical biochemistry of tears

Surv. Ophthalmol.

(1981)

HollyF.J.

Formation and rupture of the tear film

Exp. Eye Res.

(1973)

LiotetS. et al.

A new hypothesis on tear film stability

Ophthalmologica

(1987)

ChoP. et al.

The relation between invasive and noninvasive tear break-up time

Optom. Vis. Sci.

(1995)

Cited by (70)

Use of digital displays and ocular surface alterations: A review
2021, Ocular Surface
Citation Excerpt :
DED leads to tear film instability and hyperosmolarity, inflammation of the ocular surface and, ultimately, visual disturbance [82], that has shown to significantly impact patients quality of life [83]. The tear film makes the first surface that light meets before entering the eye, and given the large step of refractive index between the air and the tears, the precorneal tear film has the greatest dioptric power of any optical interface of the eye [84]. Consequently, alterations in the composition, distribution and homogeneity of the tear film may potentially lead to notable changes of the visual function [85].
Digital display use has been accepted to be implicated as a contributing factor for dry eye disease (DED). Abnormal blinking during computer operation, including a reduced blink rate and an incomplete eyelid closure, increased palpebral fissure as consequence of high visualization angles, and meibomian gland dysfunction associated to long-term display use, are behind the increased prevalence of dry eye signs and symptoms found in digital display users. Previous research reveals significant reductions in tear volume and stability, alterations in tear film composition, including increased osmolarity, inflammatory cytokines, oxidative stress markers and reduced mucin secretion, eyelid abnormalities and ocular surface damage, encompassing corneal and conjunctival staining and bulbar redness, as a direct consequence of digital display use. In this regard, individual differences in the way that the various digital displays are typically set up and used may account for differences in their effects on induced dryness signs and symptoms. Furthermore, factors such as the use of contact lenses or inappropriate working environments, usually accompanying the use of displays, may significantly increase the prevalence and the severity of induced dry eye. Other factors, such as old age and female gender are also relevant in the appearance of associated alterations. Finally, clinicians should adopt a treatment strategy based on a multidirectional approach, with various treatments being applied in conjunction.
A Review of the Compatibility of Topical Artificial Tears and Rewetting Drops with Contact Lenses
2020, Contact Lens and Anterior Eye
Citation Excerpt :
Tear biomolecules can also deposit onto a CL, depleting these molecules from the tear film [34], or enzymes deposited on a CL can degrade tear lipids, which has the potential to further destabilize the tear film [35]. This issue is supported scientifically by Albarran et al. who found that the optical quality of the eye is significantly worse in both CL and non-CL wearers after tear breakup and that optical distortions were worse in CL wearers than non-CL wearers [36]. Likewise, visual acuity and contrast sensitivity were both found to be worse after tear film break-up [19,37,38].
The purpose of this work was to review the safety and efficacy of topical artificial tears and rewetting drops with contact lenses (CLs) and the ocular surface.
Manuscripts were obtained by searching PubMed with the term “contact lens” and “artificial tears” or “rewetting drops” or “lubricant”. Recovered texts were searched to find additional references. No date exclusions were applied, though only articles written in English were included.
Preserved and non-preserved artificial tears and rewetting drops are commonly used before and after, and sometimes directly with CLs to treat CL discomfort, or ocular surface disease and to minimize the impact of wearing a CL. Data suggest that all of these products are generally safe and effective and have a minimal impact on the ocular surface when used with CLs, especially if the drops are preservative free. Data likewise suggests that comfort drops may keep CLs cleaner and improve ocular surface health.
Over-the-counter, topical, artificial tears and rewetting drops are safe and effective to use with CLs. Non-preserved drops should be used when possible to avoid eye irritation; however, if preservative-containing drops are used, preservatives that have demonstrated safety profiles should be selected rather than drops containing benzalkonium chloride or thimerosal.
Introducing a novel in vivo method to access visual performance during dewetting process of contact lens surface
2020, Contact Lens and Anterior Eye
To introduce a novel in vivo method (Visual Acuity Dry Up; VADU) for testing the visual performance during the dewetting of the pre-lens tear film on a contact lens (CL).
Thirty-nine subjects were fitted with daily disposable CL (Nelfilcon A). Visual performance and dewetting characteristics of the pre-lens tear film were simultaneously assessed using a modified multifunctional topographer (Keratograph 5 M, OCULUS Optikgeräte GmbH, Wetzlar, GERMANY) and the Non-Invasive Keratograph Dry-Up Time (NIKDUT) method. Measures were taken after five minutes and eight hours of CL wear and included the Visual Acuity Dry-Up Time (VADUT; time between last blink and visual breakdown) and the Visual Acuity Dry-Up Area (VADUA; dewetted CL area at visual breakdown) at one (VA_+0.1logMAR), two (VA_+0.2logMAR) and three (VA_+0.3logMAR) log units below maximal visual acuity (VA).
Participants lost one, two or three log units of VA after 13.1 ± 17.4 s, 20.83 ± 21.81, 34.67 ± 29.11 (VADUT), corresponding to a dewetted CL area of 4.82 ± 6.64 mm², 9.5 ± 8.26 and 13.0 ± 8.68 (VADUA), respectively. Differences in VADUT und VADUA for all visual requirements were significant (all p < 0.05). VADUT and VADUA did not vary with CL wear duration (all p > 0.05). A median VA loss of one log unit occurred five seconds after the first dewetting.
The novel VADU method can be used to analyze the role of the tear film stability on the visual performance during CL wear. Hereby, visual loss is quantified based on the threshold definition of the psychometric function.
Mechanobiology of the corneal epithelium
2018, Experimental Eye Research
There has been a drive to develop new cell based therapies to treat corneal blindness, one of the most common causes of blindness worldwide. Mechanical and physical cues are known to regulate the behavior of many cell types, however studies examining these effects on corneal epithelial cells have been limited in number and their findings have not previously been amalgamated and contrasted. Here, we provide an overview of the different types of mechanical stimuli to which the corneal epithelium is exposed and the influence that these have on the cells. Shear stress from the tear film motion and blinking, extracellular matrix stiffness and external physical forces such as eye rubbing and contact lens wear are among some of the forms of mechanical stimuli that the epithelium experiences. In vivo and in vitro studies examining the mechanobiology on corneal epithelial cells under differing mechanical environments are explored. A greater understanding of the mechanobiology of the corneal epithelium has the potential to lead to improved tissue engineering and cell based therapies to repair and regenerate damaged cornea.
Visual acuity and quality of life in dry eye disease: Proceedings of the OCEAN group meeting
2017, Ocular Surface
Citation Excerpt :
It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface [1,2]. The tear film is the first part of the ocular surface that light meets on the pathway to the retina, and the large refractive index step from the air to the tears means that the precorneal tear film has the greatest dioptric power of any optical interface of the eye [3,4]. Furthermore, the tear film compensates for the optical irregularity of the corneal epithelium surface, which is caused by the presence of numerous microvilli; without this compensation by the tear film, the quality of the transmitted light would be poor.
Dry eye disease (DED) results in tear film instability and hyperosmolarity, inflammation of the ocular surface and, ultimately, visual disturbance that can significantly impact a patient's quality of life. The effects on visual acuity result in difficulties with driving, reading and computer use and negatively impact psychological health. These effects also extend to the workplace, with a loss of productivity and quality of work causing substantial economic losses. The effects of DED and the impact on vision experienced by patients may not be given sufficient importance by ophthalmologists. Functional visual acuity (FVA) is a measure of visual acuity after sustained eye opening without blinking for at least 10 s and mimics the sustained visual acuity of daily life. Measuring dynamic FVA allows the detection of impaired visual function in patients with DED who may display normal conventional visual acuity. There are currently several tests and methods that can be used to measure dynamic visual function: the SSC-350 FVA measurement system, assessment of best-corrected visual acuity decay using the interblink visual acuity decay test, serial measurements of ocular and corneal higher order aberrations, and measurement of dynamic vision quality using the Optical Quality Analysis System. Although the equipment for these methods may be too large or unaffordable for use in clinical practice, FVA testing is an important assessment for DED.
Objective and subjective assessing efficacy of a lubricating drop in eyes wearing silicone hydrogel contact lenses
2016, Journal of Current Ophthalmology
Citation Excerpt :
The tear film is the most important refractive surface of the eye. Owing to the high difference in refractive index at the air-tear interface, this surface is considered the cardinal refractive component of the eye.1 Any local or global disruption in the tear film can give rise to both optical (e.g. high order aberration increment) and pathological (e.g. ocular surface inflammations) problems in the eye.2–4
To investigate the effect of a lubricating drop on optical quality, tear film stability, and subjective symptoms in individuals wearing silicone hydrogel contact lens.
In this one-day, prospective single-center clinical study, Pre-lens Tear Deformation Time (PL-TDT), Root-Mean-Square (RMS) of Low Order Aberrations (LOA) and High Order Aberrations (HOA), individual twelve Zernike coefficients, and subjective symptoms were assessed in 43 volunteers (mean age 19.58 ± 1.63, 86 eyes) at 6 h after inserting the contact lens and then at 60 min after instilling a lubricating drop (Comfort drops, Avizor, Madrid-Spain).
PL-TDT, LOA-RMS, and HOA-RMS values measured before drop instillation were not significantly different with those measured after drop. None of the Zernike coefficients were significantly different after instilling lubricating drop. Statistically significant decrement in both frequency and severity values in blurry vision, dryness, discomfort, burning, itching, foreign body sensation, excessive blinking, and lacrimation were seen after drop instillation (all P < 0.05).
Our results showed that although the lubricating drop did not improve the tear film stability and optical quality in the silicone hydrogel contact lens wearers, subjects experienced a subjective improvement.

View all citing articles on Scopus

View full text

Influence of the tear film on optical quality of the eye

Abstract

Acta Ophthalmol.

Am. J. Optom. Physiol. Opt.

Curr. Eye Res.

Optom. Vis. Sci.

Ophthal. Physiol. Opt.

Ophthal. Physiol. Opt.

Contact Lens Practice

Contact Lens Practice

Buffering in human tears: pH responses to acid and base challenge

Invest. Ophthalmol. Vis. Sci.

Effect of age on tear osmolality

Optom. Vis. Sci.

Refractive index and osmolality of human tears

Optom. Vis. Sci.

Determination of tear volume and tear flow

Invest. Ophthalmol. Vis. Sci.

Tear evaporation from the ocular surface

Invest. Ophthalmol. Vis. Sci.

Tear flow and evaporation in patients with and without dry eye

Ophthalmology

The viscosity of human tears

Int. Ophthalmol.

The Charles Prentice award lecture 1989. The physiology of tears

Optom. Vis. Sci.

Physiology of the lacrimal system

Bull. Soc. Belge Ophthalmol.

Clinical biochemistry of tears

Surv. Ophthalmol.

Formation and rupture of the tear film

Exp. Eye Res.

A new hypothesis on tear film stability

Ophthalmologica

The relation between invasive and noninvasive tear break-up time

Optom. Vis. Sci.