Tear-Based Oxidative Stress Biomarkers in Primary and Sarcoidosis-Associated Dry Eye Disease.

To conduct a systematic review and meta-analysis on the levels of oxidative stress markers and antioxidants in dry eye disease (DED) compared with healthy subject. The PubMed, Cochrane Library, Embase, Science Direct and Google Scholar databases were searched on 10 January 2021 for studies reporting oxidative and antioxidative stress markers in DED and healthy controls. Main meta-analysis was stratified by type of biomarkers, type of samples (tears, conjunctival cells or biopsies), Sjögren's syndrome (SS) (patients with or without SS) and by geographical zones (Asia or Europe). We included nine articles, for a total of 333 patients (628 eye samples) with DED and 165 healthy controls (451 eye samples). There is an overall increase in oxidative stress markers in DED compared with healthy controls (standard mean deviation = 2.39, 95% confidence interval 1.85-2.94), with a significant increase in lipid peroxide (1.90, 0.69-3.11), myeloperoxidase (2.17, 1.06-3.28), nitric oxide synthase 3 (2.52, 0.95-4.08), xanthine oxidase/oxidoreductase (2.41, 1.40-5.43), 4-hydroxy-2-nonenal (4HNE) (4.75, 1.67-7.84), malondialdehyde (3.00, 2.55-3.45) and reactive oxygen species (1.31, 0.94-1.68). Oxidative stress markers were higher in tears, conjunctival cells and conjunctival biopsies of DED than controls. Even if small number of studies were included for antioxidants, catalase seemed to be decreased in DED compared with healthy controls (-2.17, -3.00 to -1.34), with an increase of antioxidants in tears of DED patients without SS (1.13, 0.76-1.49). Oxidative stress markers, and probably antioxidants, were dysregulated in DED, establishing a local oxidative environment in tears, conjunctival cells and tissues.

Tear samples were collected from 37 residents of the Dominican Republic <5 d post onset (p.o.) of symptoms (mean 1.73±1.17 d p.o.) of acute hemorrhagic conjunctivitis (AHC). Sixty-two percent (23/37) of the patients had bilateral infections. Anti-enterovirus 70 (EV70) tear neutralizing activity (TNA) (10(2->3.5) U/ml) and anti-Coxsackievirus A24 variant (CA24v) TNA (10(<1-3) U/ml), but no anti-poliovirus (PV) TNA was detected. The anti-EV70 TNA in pooled tear samples sedimented in sucrose density gradient fractions that corresponded to 19-7S serum anti-PV immunoglobulin (1g). Anti-CA24v TNA sedimented as 7S1g. 1gG levels (mean, 3.13±4.2mg/ml) were higher than 1gA levels (mean, 0.92±0.98 mg/ml) in 21 of 27 tear samples. 1gG levels in tears from six patients with bilateral AHC were associated with total tear protein (p=0.003), but not with the levels of TNA or interferon (IFN). The total protein in AHC tears (5.13±1.72 mg/ml) was two-fold less than the total protein in normal tears (11.2±3.25 mg/ml). 1gA levels increased from 0.31±.3 to 1.34±1.28 mg/ml in tears collected up to 3 d p.o. of AHC. 1gM was not detected (<0.01 mg/ml). EV70 was isolated from the tears of one patient. Taken together, our results suggest that EV70 and CA24v are endemic in the Dominican Republic and that the 1992 epidemic of AHC was due to EV70. The detection of 19S (IgM) and high levels of 7S (IgG) TNA to EV70<1 d p.o. of AHC indicate a rapid ocular immune response to EV70 and suggests that virus-specific TNAs inhibit AHC virus infection.

A Comparative study of tear film dysfunction after Small incision cataract surgery (SICS) and Phacoemulsification. Aims: To study tear film dysfunction after Small Incision Cataract Surgery (SICS) and Phacoemulsification. Settings and Design: Prospective Observational and Comparative study.Materials and Methods: 164 patients that met the inclusion and exclusion criteria were enrolled into the study at the Department of Ophthalmology, Dhiraj Hospital Piparia, Waghodia, Vadodara, after getting approval from Ethics committee.82 patients underwent SICS and other 82 underwent Phacoemulsification surgery.The dry eye parameters were evaluated preoperatively and thereafter on four follow ups: first post-operative day, seventh post-operative day , 1 Month and 3 Months to study the effect of cataract surgery on tear film.The data obtained was compiled and statistically analysed.Results: Tear film dysfunction was most significant on first postoperative day and gradually came back to near normal values towards the last visit.At the end of 3 months, 21.95% and 8.54% of the patients in SICS and Phaco groups respectively had dry eye on the basis of Shirmer's -I test.Shirmer's II showed persistent dry eyes in 24.39% of the patients in SICS and 13.41% of the patients in the Phaco group.On the last visit, TBUT values in all 82 patients undergoing phaco were normal, Whereas TBUT remained abnormal in 2.44% of the patients in SICS group.TMH values were ineffective in determining tear film function. Conclusion:Our study shows that tear film dysfunction occurs more after SICS than Phacoemulsification surgery.Modifying the risk factors associated with the surgical procedure and initiation of topical lubricating agents in the early postoperative period can minimize the incidence and duration of recovery of dry eye after cataract surgery.

The tear film is essential for the integrity of the ocular surface. In ocular diseases such as dry eye syndrome (DES), tear film osmolarity is increased relative to normal physiological conditions. DES can be caused by deficiency in lachrymation, hyperevaporation, or surface alterations. Carnitines, shown to have osmoregulatory properties, are thought to regulate tear film osmolarity, thus protecting the corneal surface from damage. We investigated the presence of carnitine in tears, compared tear carnitine concentrations in healthy subjects and in DES patients and speculate on carnitine's potential role as a protective agent in the tear film. Tears were collected from 10 healthy subjects and 10 DES patients. Carnitine levels were assessed by high performance liquid chromatography-mass spectrometry. Carnitine and its derivatives were detected in the tear samples. In DES patients, concentrations were substantially lower than in healthy subjects; the mean concentrations were L-carnitine, 3.27 +/- 0.80 and 8.94 +/- 0.50 microMol/L; L-acetylcarnitine, 1.66 +/- 0.50 and 3.05 +/- 0.65 microMol/L; and L-propionylcarnitine, 0.30 +/- 0.11 and 0.57 +/- 0.13 microMol/L, in DES patients and healthy subjects, respectively. Although increased tear film osmolarity has been previously observed in DES patients, our study showed lower carnitine levels in DES patients than in healthy subjects, rather than the increased levels expected, although a causal relationship between carnitine levels and hyperosmolarity has not been established. The damage to ocular surface cells because of exposure to hypertonic tear film observed in DES may be partially because of an imbalance in the concentration of carnitine molecules in the tear film relative to the ocular surface cells. We propose, therefore, that carnitine solutions may have a role in preventing the adverse effects of observed hyperosmolarity and suggest that further studies are now warranted to investigate the clinical application of carnitine in the treatment of DES.

The autonomic nervous system plays a crucial role in the maintenance of homeostasis. Neurogenic inflammation due to decreased stability of tear film may induce changes in autonomic nerve activity, which could be associated with symptom expression.This study aimed to measure biological parameters that represent autonomic nerve activity in dry eye (DE)s caused by tear film dysfunction and investigate their relationship with symptom intensity. This prospective, cross-sectional, comparative study evaluated 34 eyes of 34 participants (mean age: 52.5 ± 13.4 years; range: 20–81 years) without keratoconjunctival damage. Nineteen eyes in the DE group showed DE symptoms and tear break-up time (TBUT) of ≤5 seconds (short TBUT DE); the 15 eyes in the non-DE group showed no DE symptoms. Autonomic nerve activity was measured for 10 minutes—starting and ending 5 minutes before and after instilling ophthalmic solution—and evaluated using the low-frequency component (LF) to the high-frequency component (HF) ratio of heart rate variability (autonomic balance). The pre-ophthalmic solution administration LF/HF ratio was not significantly different (P = 0.59) between the two groups, however, the standard deviation of the LF/HF ratio (LF/HF-SD) tended to be higher in the DE group than that in the non-DE group (P = 0.086). The DE symptom intensity was significantly related to LF/HF-SD (P = 0.005), which significantly decreased after ophthalmic solution administration in the DE group (P = 0.04). The large fluctuations in autonomic balance may be key for the understanding of the mechanism underlying DE symptoms.

Elevated blood glucose levels may disrupt tear film and meibomian gland function, contributing to dry eye disease (DED) and meibomian gland dysfunction (MGD). This study aimed to explore the relationship between hyperglycemia and DED parameters. A cross-sectional study at Chifeng Chaoju Eye Hospital (June-August 2024) included 56 participants with DED symptoms. Tear meniscus height (TMH), non-invasive tear film breakup time (FNIBUT, ANIBUT), bulbar redness, and meibomian gland atrophy (U-LAMG, L-LAMG) were assessed using a non-invasive ocular surface analyzer. Fasting blood glucose levels stratified patients into high (≥7 mmol/l) and normal (<7 mmol/l) groups, and their association with DED parameters was analyzed. Among 56 patients (mean age 52.5 ± 18.0 years), those with elevated glucose levels (n=28) had more severe DED symptoms (OSDI, p = 0.046), lower TMH, FNIBUT, ANIBUT, and higher bulbar redness scores (all p < 0.05). In contrast, lower glucose levels were associated with greater U-LAMG and L-LAMG atrophy (p < 0.05). Glucose positively correlated with intraocular pressure (IOP), redness, U-LAMG, and L-LAMG but negatively correlated with TMH, FNIBUT, and ANIBUT (all p < 0.05). Hyperglycemia is linked to impaired tear film stability, meibomian gland function, and DED symptoms. Ocular surface disorders in individuals with diabetes may be prevented by effective glycemic control.

Recent evidence suggests that dry eye (DE) may be comorbid with other chronic pain conditions. To evaluate DE as a comorbid condition in the U.S. veteran population. Retrospective review of veterans seen in the Veterans Administration Healthcare System (Veteran Affairs) between January 1, 2010, and December 31, 2014. Dry eye and nonocular pain disorders were ascertained by International Classification of Diseases, Ninth Revision (ICD-9) codes. Dry eye was further separated into ICD-9 codes representing tear film dysfunction or ocular pain. χ2 and logistic regression analyses were used to examine frequency and risk of DE, ocular pain, and tear film dysfunction by pain disorders. Of 3,265,894 veterans, 959,881 had a DE diagnosis (29.4%). Dry eye frequency increased with the number of pain conditions reported (P < 0.0005). Ocular pain was most strongly associated with headache (odds ratio [OR] 2.98; 95% confidence interval [CI] 2.95-3.01), tension headache (OR 2.64; 95% CI 2.58-2.71), migraine (OR 2.58; 95% CI 2.54-2.61), temporomandibular joint dysfunction (OR 2.39; 95% CI 2.34-2.44), pelvic pain (OR 2.30; 95% CI 2.24-2.37), central pain syndrome (OR 2.24; 95% CI 1.94-2.60), and fibromyalgia/muscle pain (OR 2.23; 95% CI 2.20-2.26), all P < 0.0005. Tear film dysfunction was most closely associated with osteoarthritis (OR 1.97; 95% CI 1.96-1.98) and postherpetic neuralgia (OR 1.95; 95% CI 1.90-2.00), both P < 0.0005. Dry eye, including both ocular pain and tear film dysfunction, is comorbid with pain conditions in this nationwide population, implying common mechanisms.

Dry eye disease (DED) is a clinically significant multifactorial disorder of the ocular surface and tear film as it results in ocular discomfort and visual impairment and predisposes the cornea to infections. It is important for the quality of life and tends to be a chronic disease. It is also common, as the prevalence is estimated between 5 % to 30 % and this increases with age. Therefore, it is recognised as a growing public health problem that requires correct diagnosis and appropriate treatment. There are two main categories of DED: the deficiency of tear production (hyposecretive), which includes Sjögren syndrome, idiopathic or secondary to connective tissue diseases (e.g. rheumatoid arthritis), and non-Sjögren syndrome (e.g. age-related); and the tear evaporation category, where tears evaporate from the ocular surface too rapidly due to intrinsic causes (e.g. meibomian gland disease or eyelid aperture disorders) or extrinsic causes (e.g. vitamin A deficiency, contact lenses wear, ocular allergies). Management of the disease aims to enhance the corneal healing and reduce patient’s discomfort. This is based on improving the balance of tear production and evaporation by increasing the tear film volume (lubrication drops) and improving quality of tear film (ex omega-3 supplements, lid hygiene, tetracyclines), reducing the tear film evaporation (paraffin ointments, therapeutic contact lenses), reducing tear’s drainage (punctal plugs, cautery) and finally by settling down the ocular surface inflammation (steroids, cyclosporine, autologous serous), as appropriate. In this article we will review the clinical presentation, differential diagnosis and treatment options for DED.

This report describes the development of an artificial intelligence system for automated assessment of tear film stability and the classification of tear breakup patterns (BUPs), supporting precise dry eye (DE) diagnosis and personalised treatment under the framework of tear film-oriented diagnosis. A dataset of 143 eyes (98 with dry eye, 45 healthy) was analysed. Participants were evaluated using the Ocular Surface Disease Index, Keratograph 5M assessments (tear meniscus height, non-invasive tear breakup time, lipid layer thickness grade and meiboscore) and the Schirmer I test. Tear film breakup with fluorescein was video recorded and processed via a mask region-based convolutional neural network for tear film segmentation and a temporal segment network for temporal feature extraction. The proposed system performed automated evaluation of DE and identified four representative BUPs, including line break, dimple break, spot break and random break. Model performance was assessed using key metrics, including accuracy, precision, recall and F1 score. The diagnostic model achieved 91.8% accuracy in detecting tear film breakup and 98% accuracy in identifying DE. The classification model reached 88% accuracy, with high precision and recall for line and spot break. Gradient-weighted class activation mapping indicated effective capture of morphological features. Significant differences in ocular surface parameters were observed between DE and healthy eyes, as well as among BUP groups, confirming the system's clinical relevance. This artificial intelligence system offers an objective, non-invasive approach to supporting DE diagnosis and classifying BUPs, reducing interobserver variability and extensive training. By accurately detecting tear film instability and deficiency patterns, it supports targeted tear film-oriented therapy and advances personalised treatment strategies.

BackgroundDry eye disease (DED) predominantly results from elevated tear film osmolarity, which can not only cause ocular inconvenience but may lead to visual impairments, severely compromising patient well‐being and exerting substantial economic burdens as well. Astaxanthin (AST), a member of the xanthophylls and recognized for its robust abilities to combat inflammation and oxidation, is a common dietary supplement. Nonetheless, the precise molecular pathways through which AST influences DED are still poorly understood.MethodsTherapeutic targets for AST were identified using data from the GeneCards, PharmMapper, and Swiss Target Prediction databases, and STITCH datasets. Similarly, targets for dry eye disease (DED) were delineated leveraging resources such as the Therapeutic Target Database (TTD), DisGeNET, GeneCards, and OMIM databases, and DrugBank datasets. Interactions among shared targets were charted and displayed using CytoScape 3.9.0. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were conducted to elucidate the functions of pivotal targets within the protein–protein interaction network. Molecular interactions between AST and key targets were confirmed through molecular docking using AutoDock and PyMOL. Molecular dynamics simulations were performed using GROMACS 2022.3. Viability of human corneal epithelial cells (hCEC) was assessed across varying concentrations of AST. A mouse model of experimental DED was developed using 0.1% benzalkonium chloride (BAC), and the animals were administered 100 mg/kg/day of AST orally for 7 days. The efficacy of the treatments was assessed through a series of diagnostic tests to evaluate the condition of the ocular surface after the interventions. The levels of inflammation and oxidative stress were quantitatively assessed using methods such as reverse transcription‐polymerase chain reaction (RT‐PCR), Western blot, and immunofluorescence staining.ResultsNetwork pharmacology suggests that AST may alleviate DED by influencing oxidation–reduction signaling pathways and reducing oxidative stress provoked by BAC. In vivo experiments demonstrated an improved overall condition in AST‐administered mice in contrast to the control group. Immunofluorescence staining analyses indicated a decrease in Keap1 protein in the corneal tissues of AST‐treated mice and a significant increase in Nrf2 and HO‐1 protein. In vitro studies demonstrated that AST significantly enhanced cell viability and suppressed reactive oxygen species expression under hyperosmotic (HS) conditions, thereby protecting the human corneal epithelium.ConclusionAST is capable of shielding mice from BAC‐induced DED, decelerating the progression of DED, and mitigating oxidative stress damage under HS conditions in hCEC cells. The protective impact of AST on DED may operate through stimulating the Keap1‐Nrf2/HO‐1 signaling pathway. Our research findings indicate that AST may be a promising treatment for DED, offering new insights into DED treatment.

Seeing through tears: Understanding and managing dry eye disease.

The aim of this review is to summarize the results of a consensus meeting held by a group of experts in dry eye disease (DED) to discuss the importance of tear substitutes in the treatment of DED. The meeting focused especially on the main characteristics of lacrimal substitutes, the development of in vitro models to investigate DED pathophysiology and treatment, the importance of conducting rigorous clinical trials, the requirements of the upcoming European Legislation on medical devices, the advances in the formulation of safer preservatives, the peculiarities of treatment in younger subjects, and the importance of an updated terminology for lacrimal substitutes. A literature search was conducted using MEDLINE, with different combinations of pertinent keywords, depending on the subject under discussion, such as "dry eye disease"; "tear substitutes"; "in vitro models"; "ocular surface"; "clinical trials"; "European Regulation"; "preservatives" "younger patients". Also, each author included in the discussion selected articles from their personal library. Using a consensus-based method called nominal group technique to reach a conclusion and proposal for a new classification of eye drops used to improve the tear film and ocular surface epithelia, the experts also conducted a round table meeting. The new terms proposed by the authors are "wetting agents", "multiple-action tear substitutes" or "ocular surface modulators". The new classification is needed to distinguish eye drops used to improve the tear film and ocular surface epithelia, in line with the new definition of DED, which recognizes the loss of ocular homeostasis, and the creation of a vicious circle of chronic inflammation and ocular damage as fundamental aspects of DED pathophysiology. Although tear substitutes have been historically used to provide eye lubrication to the ocular surface, recent advances in the pathophysiology of dry eye disease (DED) clarified that treatment should not just focus on tear film quality or quantity, but address the loss of homeostasis of the ocular surface, blocking the vicious circle of chronic inflammation and ocular damage. Given the scant comparative evidence on tear substitutes currently on the market, further studies should focus on developing new agents, considering the advantages provided by in vitro models, importance of conducting rigorous clinical trials, availability of less harmful preservatives and obligations related to the new European legislation on medical devices. Based on the discussion of these topics, a group of experts held a consensus meeting to identify new and more appropriate terms for different tear substitutes. The proposed terms are wetting agents, multiple-action tear substitutes and ocular surface modulators. Regardless of the agent used, it is important to note that tear substitutes represent one of many options for DED treatment, which should not overlook the psychological aspects of the disease and the peculiarities of younger subjects, who seem to have a higher risk for DED, possibly related to digital devices excessive use.

It is well-known that diabetes is one of the major causes of dry eye disease (DED). As DED can lead to serious ocular surface complications such as punctate keratitis, corneal erosion, corneal scarring, corneal perforation and visual loss, research is ongoing to investigate ways of improving the diagnosis of DED in patients with diabetes. This thesis investigated the role of inflammatory cytokines and metabolic proteins in tear fluid as a non-invasive, objective measure of inflammation in the diagnosis of type 2 diabetes (T2D)-related DED. In this thesis, a number of studies were performed to investigate potential tear fluid biomarkers and comparing them to the established clinical and laboratory measures used in DED diagnosis. It was important to evaluate the clinical behaviours of eye care professionals, such as ophthalmologists and optometrists with respect to the diagnosis and management of diabetes-related DED (Chapter 3). Thus, the online survey was conducted among 194 eye care professionals who work in the UK and Mongolia, to evaluate and compare their preferences for specific clinical procedures used to diagnose the presence of DED in diabetes. For example, how these may differ, depending on the practitioners' profession (ophthalmologist and optometrist) and the countries they work in. This study is the first time that the awareness of eye care professionals in the diagnosis and the management of diabetes-related DED in different regions of the world has been investigated. The results of the survey showed that eye care professionals in both countries have similar practice behaviours for diagnosing and treating diabetes-related DED. That is, ophthalmologists in the UK and in Mongolia have similar practice behaviours in diagnosing diabetes-related DED, and its severity, as for optometrists in the UK. Before commencing the studies to analyse protein biomarkers in tear fluids, it was important to establish the best possible means of sampling and storing tear samples, along with the optimal method of analysing them (Chapter 4). Therefore, a study was conducted to investigate the methodology of tear sampling, storage, analysis, sample centrifugation duration and speed. For tear biomarker assessment, a pilot study investigating the detectability of metabolic proteins in 1 μl tears was conducted (Chapter 5). This study is the first time that metabolic proteins such as Leptin, Insulin, C-peptide, GIP and active Ghrelin, have been shown to be detected in human tears collected from “healthy” individuals using Luminex Xmap technology. The results of this study showed that Leptin could be used in the future as a potential diagnostic biomarker of ocular surface disorders and, possibly, in determining the effects of metabolic disorders, as it has a low intra-subject confidence interval (CI) and a high intra-class correlation coefficient (ICC). A pilot study investigating the correlation between the presence of tear fluid inflammatory cytokines and tear fluid stability (assessed using tear evaporation rate [TER]; and non-invasive tear break-up time [NITBUT]) in healthy subjects was carried out (Chapter 6). This study also investigated the effect of time of day on TER and NITBUT values, and its possible correlation with tear cytokine concentrations in healthy subjects. The results revealed that the NITBUT and TER values had no significant variability over a day, or on different days, in healthy subjects, when the humidity and temperature of the examination room were constant. However, some tear fluid cytokine concentrations did show inter- and intra-day variability, without any consistent correlation with TER diurnal variation. Before commencing the study in a large cohort, a pilot study investigating the detectability of inflammatory cytokines and metabolic proteins in 1 μl tears collected from patients with type 2 diabetes (T2D; with and without DED) and DED-only (without T2D) was conducted (Chapter 7). The concentrations of 14 inflammatory cytokines, six metabolic proteins, ocular surface parameters, DED-related symptoms and quality of life (QoL) were evaluated and compared in a total of 122 subjects divided into four study groups as: T2D with DED, T2D-only (without DED), DED-only (without T2D) and healthy controls (Chapter 8). Overall, the results of this study showed that the ocular surface parameters and DED-related symptoms were similar for patients in the T2D+DED group and the DED-only group. In addition, patients in the T2D-only group had similar ocular surface parameters to healthy controls. Tear fluid Interleukin (IL)-6 and IL-8 concentrations were significantly higher in the T2D+DED group than the T2D-only group, DED-only group and healthy controls, which suggests that IL-6 and IL-8 could potentially be diagnostic biomarkers of T2D-related DED. These studies show that tear fluid biomarker analysis is feasible and it can be utilised in the objective diagnosis of T2D-related DED. This research helps to improve the understanding of the inflammatory mechanisms and markers of DED in T2D. However this complex process will require further research to identify the most appropriate biomarkers.

Corneal refractive surgeries are one of the commonly performed procedures for correction of refractive errors. Tear film abnormality is the most common postoperative complication of corneal refractive surgeries. Consequently, these procedures represent a clinically significant cause of dry eye disease. The mechanisms which lead to dry eye disease include corneal sensory nerve dysfunction, ocular surface desiccation, glandular apoptosis and ocular surface inflammation. Although transient tear film abnormalities occur in almost all patients following surgery, patients with pre-existing dry eye symptoms or dry eye disease are at significant risk of developing more severe or long-term ocular surface disease. As such, careful patient selection and preoperative evaluation is essential to ensuring successful surgical outcomes. This is particularly important with LASIK which has the strongest association with dry eye disease. Appropriate surface lubrication and anti-inflammatory therapy remains the cornerstone treatment. Timely and effective management is important to facilitate visual rehabilitation and reduce the risk of secondary complications. In this review we describe the causes, pathophysiology, risk factors, manifestations, and management of tear film dysfunction and dry eye disease following corneal refractive surgery.

To evaluate the effects of tear film breakup on higher order aberrations of the anterior cornea in normal, dry, and post-LASIK eyes. In a prospective study, 120 eyes (120 subjects) comprised three groups: post-LASIK eyes, dry eyes, and normal eyes. Tear film break-up time (BUT) was measured by fluorescein dye under slit-lamp microscopy. Corneal topographies were measured by videokeratography immediately after the following times: post-blink, 1/2 BUT, BUT, and after normal saline application. VOL-Pro software processed topographies to obtain and analyze higher order aberrations (3rd through 6th orders over 6 mm) of the anterior comeal surface. The measurement time scale was set by the BUT: significantly less for dry eyes (8.3 +/- 3.4 seconds) than post-LASIK eyes (11.3 +/- 5.1 seconds) or normal eyes (10.3 +/- 5.6 seconds). Normal and dry eye subjects showed a pattern of significant increase of aberrations from post-blink through BUT and decrease of aberrations after saline addition in coma, trefoil, and 3rd through 6th order aberrations. Post-LASIK eyes exhibited no significant difference between phases. Disruption of the tear film increases anterior corneal higher order aberrations in normal eyes and more rapidly in dry eyes. The increase in aberrations caused by conventional LASIK is greater than that of tear film-related effects.