Effects of tear film dynamics on quality of vision

Abstract

The precorneal tear film is maintained by blinking and exhibits different phases in the tear cycle. The tear film serves as the most anterior surface of the eye and plays an important role as a first refractive component of the eye. Alterations in tear film dynamics may cause both vision-related and ocular surface-related symptoms. Although the optical quality associated with the tear film dynamics previously received little attention, objective measurements of optical quality using wavefront sensors have enabled us to quantify optical aberrations induced by the tear film. This has provided an objective method for assessing reduced optical quality in dry eye; thus, visual disturbances were included in the definition of dry eye disease in the 2007 Dry Eye Workshop report. In addition, sequential measurements of wavefront aberrations have provided us with valuable insights into the dynamic optical changes associated with tear film dynamics. This review will focus on the current knowledge of the mechanisms of wavefront variations that are caused by different aspects of tear film dynamics: specifically, quality, quantity and properties of the tear film, demonstrating the respective effects of dry eye, epiphora and instillation of eye drops on the quality of vision.

Cataract surgery and dry eye disease: A review

“…While the published evidence shows inconsistencies, probably due to the discordance between DED symptoms and signs, 44 , 45 as well as the variability of current DED assessment methodologies, there clearly is an association between cataract surgery and both development of iatrogenic DED and exacerbation of pre-existing DED. 7 – 18 , 47 – 51 As discussed, disruption in tear film homeostasis is a key component in the pathogenesis of DED and there are a number of possible intra- and post-operative factors in modern phacoemulsification cataract surgery (PCS) which can disturb the tear film milieu. 6 These factors appear to include incisional corneal nerve injury and ocular surface damage from the toxic effects of components of eye drops; ocular surface drying/repeated irrigation; phototoxicity; and surgical trauma ( Figure 1 ).…”

“…They require, as the first refractive component of the eye, an intact, healthy pre-corneal tear film. 10 …”

Changes of wavefront aberrations and corneal surface regularity in dry eye patients measured with OPD Scan III

“…According to the study, tear lm instability and ocular surface damage are thought to be main courses of visual disturbance which resulted in the increased wavefront aberrations and corneal surface irregularity [24]. However, few study focused on evaluating both wavefront aberrations and corneal surface irregularity in DE patients.…”

Kinetic visual acuity is correlated with functional visual acuity at higher speeds

“…Although DE is a very common ocular surface disease and major cause of decreased FVA, which should be maintained in high-speed driving, the patients may be asymptomatic and diagnosed with symptoms as well as loss of homeostasis of the tear film 29. Visual disturbance in patients with DE may be due to a blurry optical image with increased aberration and scattering induced by an unstable tear film 30 31. Patients with DE may recognise their symptoms only as eye fatigue or presbyopia, so DE may be often overlooked 32.…”