The importance of the precorneal tear film for the quality of optical imaging

Dry Eye Syndrome in Patients with Diabetes Mellitus: Prevalence, Etiology, and Clinical Characteristics

There has been substantial progress in our understanding of the ocular surface system/lacrimal function unit in the past 15 years. Keratoconjunctivitis sicca, more commonly referred to as dry eye syndrome (DES), is the most frequently encountered condition and diabetes mellitus (DM) has been identified as one of the leading causes of DES. Poor glycemic control affects both the anterior and the posterior segments of the eye and increasing prevalence of diabetes-associated DES (DMDES) has been reported in recent years. The pathogenesis and specific features of DMDES remain uncertain and interventions are limited to those used in DES. This review outlines the pathogenesis, clinical manifestations, and the current preventive and treatment strategies for diabetes-related DES.

Safety and comfort evaluation of a new formulation of Visine(®) lubricant eye drops containing HydroBlend™ and GentlePur™

PURPOSE

To evaluate the clinical safety and comfort of a new benzalkonium chloride-free Visine(®) lubricant eye drop formulation (Hydroblend™ and GentlePur™) in healthy and dry eye subjects.

METHODS

This was a single-site, open-label clinical study comprised of 22 healthy and 22 dry eye subjects. Subjects were instructed to instill 1-2 drops of the test product four times a day for 2 weeks and were examined at visit 1 (day 0), visit 2 (day 7), and visit 3 (day 14). Assessments at each visit included postdosing product usage comfort scores, predosing fluorescein corneal staining score, predosing visual acuity, and pre- and postdosing ocular structure change using slit-lamp biomicroscopy. Adverse events were monitored throughout the course of the study.

RESULTS

Throughout the 14 days of the trial period, subjects from both healthy and dry eye groups rated the eye drops as "very comfortable". For dry eye group, the mean product usage comfort scores for the first 3 minutes postdosing ranged from 8.5 to 8.8 at visit 1 and 9.2 to 9.6 at visit 3 on a 0-10 point scale, with 0 being very uncomfortable and 10 being very comfortable. The mean corneal staining scores over five corneal regions changed from 0.65 at visit 1 to 0.39 at visit 3 for dry eye group. The individual region corneal staining scores were also decreased from visits 1 to 3 for dry eye group. All subjects maintained pretreatment means visual acuity at visits 2 and 3. Biomicroscopic examination indicated no structural changes at all visits. There were no significant adverse events reported during the course of the study.

CONCLUSION

The study confirms that GentlePur™ is an appropriate choice as a preservative for ocular application. The new formulation was safe and comfortable when used four times a day in healthy and dry eye subjects.

Impact of epiphora on vision-related quality of life

Background

The study aimed to evaluate vision-related quality of life (QOL) in epiphora (excessive tear production) patients.

Methods

A total of 342 epiphora patients who visited ophthalmology clinics at 21 general hospitals during a 1-week period were enrolled; 245 females and 97 males with a mean age of 52 ± 13 years. Participants completed a self-administered questionnaire on the extent to which epiphora limited their daily activities. Questions on frequency of discomfort with daily activities were answered on scale of a 0–4. Daily activities that were assessed included reading, daytime and nighttime driving, working at a computer, watching TV, work-related activities, household activities, outdoor activities, interpersonal relations, and general happiness. A correlation analysis was performed between the scores and patient ages. Scores were compared with the clinical factors of gender, bilaterality, and lacrimal irrigation pattern. Presurgical and postsurgical scores in a subset of epiphora patients who underwent surgery were compared.

Results

Outdoor activities were among those that epiphora most significantly hindered. Age had a negative correlation with interpersonal relations scores. Female patients tended to have more discomfort than males in conducting household activities, outdoor activities, and interpersonal relations. Bilaterality showed no differences in QOL. Patients with complete obstruction of lacrimal irrigation recorded higher scores in all daily activities than those with partial or no obstruction. For vision-related QOL, post-surgical scores were improved significantly compared with pre-surgical scores.

Conclusion

Epiphora can affect a broad array of daily activities. Corrective measures for epiphora can improve vision-related QOL, and this may provide guidance for physicians in managing epiphora patients.

Measurement of a multi-layered tear film phantom using optical coherence tomography and statistical decision theory

To extend our understanding of tear film dynamics for the management of dry eye disease, we propose a method to optically sense the tear film and estimate simultaneously the thicknesses of the lipid and aqueous layers. The proposed method, SDT-OCT, combines ultra-high axial resolution optical coherence tomography (OCT) and a robust estimator based on statistical decision theory (SDT) to achieve thickness measurements at the nanometer scale. Unlike conventional Fourier-domain OCT where peak detection of layers occurs in Fourier space, in SDT-OCT thickness is estimated using statistical decision theory directly on the raw spectra acquired with the OCT system. In this paper, we demonstrate in simulation that a customized OCT system tailored to ~1 µm axial point spread function (FWHM) in the corneal tissue, combined with the maximum-likelihood estimator, can estimate thicknesses of the nanometer-scale lipid and micron-scale aqueous layers of the tear film, simultaneously, with nanometer precision. This capability was validated in experiments using a physical phantom that consists of two layers of optical coatings that mimic the lipid and aqueous layers of the tear film.

Higher order aberrations of the corneal surface after laser subepithelial keratomileusis

PURPOSE

To evaluate the changes of higher order aberrations (HOAs) before and after laser subepithelial keratomileusis (LASEK) and to analyze the influence of tear film instability on HOAs of the corneal surface after LASEK.

METHODS

In this cross-sectional study, 31 patients who underwent LASEK were divided into dry eye (16 patients, 32 eyes) and non-dry eye groups (15 patients, 30 eyes). Uncorrected distance visual acuity, spherical equivalent refraction, ablation depth, tear film parameters and Ocular Surface Disease Index (OSDI) questionnaire scores were evaluated in both groups. Total HOA root mean square (RMS), third-order coma, third-order trefoil and fourth-order spherical aberration (SA) of the corneal surface immediately and at 10 seconds after blinking were measured before and after surgery.

RESULTS

The total HOA RMS, coma, trefoil and SA significantly increased after LASEK compared with preoperative values in both groups. In the dry eye group, total HOA RMS, coma and trefoil significantly increased except for SA at 10 seconds after blinking compared with those measured immediately after blinking. In addition, the changes of total HOA RMS, coma and trefoil were negatively correlated with tear film break-up time (R = -0.420, -0.473 and -0.439, respectively), but positively correlated with OSDI score (R = 0.433, 0.499 and 0.532, respectively). In the non-dry eye group, there were no significant differences between HOAs measured at 10 seconds after blinking and those measured immediately after blinking.

CONCLUSIONS

The HOAs including coma, trefoil and SA significantly increased after LASEK. The tear film instability in the dry eye can be associated with more deterioration of the optical quality after LASEK, due to more significant increase of total HOA RMS, coma and trefoil.

New testing options for diagnosing and grading dry eye disease

PURPOSE

To describe new options for diagnosis and severity grading of dry eye disease.

DESIGN

Perspective on technological advancements to identify tear dysfunction and their value in diagnosing and grading dry eye disease.

METHODS

Evidence is presented on new and evolving technologies to measure tear stability, composition, and meniscus height and their role in dry eye diagnosis and therapeutic efficacy grading is assessed.

RESULTS

Evolving concepts regarding pathogenesis and new technologies to evaluate the tears and ocular surface have improved the ability to diagnose, classify, and grade the severity of dry eye disease. New technologies include noninvasive imaging of tear stability and tear meniscus height as a measure of tear volume and tear composition (osmolarity, lacrimal factors, inflammatory mediators, growth and differentiation factors). Approved tests, such as tear osmolarity and tear imaging, are being integrated into clinical practice and may eventually supplant certain traditional tests that have greater variability and less sensitivity. Other tests, such as molecular assays of tears and conjunctival cells, are currently being used in studies investigating pathogenesis and therapeutic mechanism of action. They may eventually translate to routine clinical practice.

CONCLUSIONS

New technologies have emerged that can noninvasively evaluate the tears and measure disease-associated compositional changes. These tests are being integrated into clinical practice and therapeutic trials for diagnosis, classification, and severity grading of dry eye disease.

Diagnosis of dry eye disease and emerging technologies

Dry eye is one of the most commonly encountered problems in ophthalmology. Signs can include punctate epithelial erosions, hyperemia, low tear lakes, rapid tear break-up time, and meibomian gland disease. Current methods of diagnosis include a slit-lamp examination with and without different stains, including fluorescein, rose bengal, and lissamine green. Other methods are the Schirmer test, tear function index, tear break-up time, and functional visual acuity. Emerging technologies include meniscometry, optical coherence tomography, tear film stability analysis, interferometry, tear osmolarity, the tear film normalization test, ocular surface thermography, and tear biomarkers. Patient-specific considerations involve relevant history of autoimmune disease, refractive surgery or use of oral medications, and allergies or rosacea. Other patient considerations include clinical examination for lid margin disease and presence of lagophthalmos or blink abnormalities. Given a complex presentation and a variety of signs and symptoms, it would be beneficial if there was an inexpensive, readily available, and reproducible diagnostic test for dry eye.

Racial variations in interfacial behavior of lipids extracted from worn soft contact lenses

PURPOSE

To explore interfacial behaviors and effects of temperature and dilatation on dynamic properties of multilayered human tear lipids extracted from silicone hydrogel (SiH) lenses worn by asymptomatic Asian and white subjects.

METHODS

Interfacial properties of lipids extracted from Focus N&D lenses worn by 14 subjects continuously for 1 month were studied. The lipids were deposited on an air bubble immersed in a model tear electrolyte (MTE) solution to form 100 ± 20-nm-thick films. Surface pressure was recorded during slow expansion/contraction cycles to evaluate compressibility and hysteresis of lipid films. Films were also subjected to fast step-strain dilatations at temperatures of 22 to 45°C for their viscoelastic property assessment.

RESULTS

Isocycles for Asian and white lipids were similar at low surface pressures but had distinctly different compressibility and hysteresis at dynamic pressures exceeding 30 mN/m. Rheological parameters of reconstituted lipids were also dissimilar between Asian and white. The elastic modulus E∞ for white lipids was 1.5 times higher than that for Asian lipids, whereas relaxation time (t) was on average 1.3 times higher for Asian. No significant changes were observed in rheological properties of both Asian and white lipids when temperature increased from 22.0 to 36.5°C. However, for white lipids, E∞ reduced considerably at temperatures higher than 42.0°C, whereas t remained unchanged. For Asian lipids, both E∞ and t started to decline as temperature increased to 38°C and higher.

CONCLUSIONS

Higher elastic modulus of white lipids and elasticity threshold at certain deformations indicate stronger structure and intermolecular interactions as compared with more viscous Asian lipids. The differences in interfacial behaviors between Asian and white lipids may be associated with the differences in their chemical compositions.

Rethinking dry eye disease: a perspective on clinical implications

Publication of the DEWS report in 2007 established the state of the science of dry eye disease (DED). Since that time, new evidence suggests that a rethinking of traditional concepts of dry eye disease is in order. Specifically, new evidence on the epidemiology of the disease, as well as strategies for diagnosis, have changed the understanding of DED, which is a heterogeneous disease associated with considerable variability in presentation. These advances, along with implications for clinical care, are summarized herein. The most widely used signs of DED are poorly correlated with each other and with symptoms. While symptoms are thought to be characteristic of DED, recent studies have shown that less than 60% of subjects with other objective evidence of DED are symptomatic. Thus the use of symptoms alone in diagnosis will likely result in missing a significant percentage of DED patients, particularly with early/mild disease. This could have considerable impact in patients undergoing cataract or refractive surgery as patients with DED have less than optimal visual results. The most widely used objective signs for diagnosing DED all show greater variability between eyes and in the same eye over time compared with normal subjects. This variability is thought to be a manifestation of tear film instability which results in rapid breakup of the tearfilm between blinks and is an identifier of patients with DED. This feature emphasizes the bilateral nature of the disease in most subjects not suffering from unilateral lid or other unilateral destabilizing surface disorders. Instability of the composition of the tears also occurs in dry eye disease and shows the same variance between eyes. Finally, elevated tear osmolarity has been reported to be a global marker (present in both subtypes of the disease- aqueous-deficient dry eye and evaporative dry eye). Clinically, osmolarity has been shown to be the best single metric for diagnosis of DED and is directly related to increasing severity of disease. Clinical examination and other assessments differentiate which subtype of disease is present. With effective treatment, the tear osmolarity returns to normal, and its variability between eyes and with time disappears. Other promising markers include objective measures of visual deficits, proinflammatory molecular markers and other molecular markers, specific to each disease subtype, and panels of tear proteins. As yet, however, no single protein or panel of markers has been shown to discriminate between the major forms of DED. With the advent of new tests and technology, improved endpoints for clinical trials may be established, which in turn may allow new therapeutic agents to emerge in the foreseeable future. Accurate recognition of disease is now possible and successful management of DED appears to be within our grasp, for a majority of our patients.

[Influence of dry eye syndrome on glaucoma diagnostic procedures]

Approximately 50-60% of primary open angle glaucoma patients suffer from dry eye and ocular surface disease and have a reduced corneal thickness. The measurements by imaging procedures are weakened by signal noise and perimetry procedures are affected by generalized loss of sensitivity. In dry eye patients, possible influences on new perimetry procedures, such as frequency doubling technology (FDT), flicker-defined form (FDF) perimetry and pulsar perimetry (PP) potentially result from stray light and reduced contrast sensitivity. In glaucoma patients with ocular surface disturbances, measuring procedures with high sensitivity and low specificity should be carefully checked for plausibility by the examiner. Using these procedures uncritically involves the danger of over interpretation in terms of non-existent glaucoma progression. If necessary, eyes should be pretreated with lubricating eye drops or therapy should be switched to preservative-free pressure lowering drops. Afterwards, new control measurements should be taken to exclude glaucoma pseudoprogression.

A preliminary investigation into the effects of ocular lubricants on higher order aberrations in normal and dry eye subjects

PURPOSE

To study the effects of ocular lubricants on higher order aberrations in normal and self-diagnosed dry eyes.

METHODS

Unpreserved hypromellose drops, Tears Again™ liposome spray and a combination of both were administered to the right eye of 24 normal and 24 dry eye subjects following classification according to a 5 point questionnaire. Total ocular higher order aberrations, coma, spherical aberration and Strehl ratios for higher order aberrations were measured using the Nidek OPD-Scan III (Nidek Technologies, Gamagori, Japan) at baseline, immediately after application and after 60 min. The aberration data were analyzed over a 5mm natural pupil using Zernike polynomials. Each intervention was assessed on a separate day and comfort levels were recorded before and after application. Corneal staining was assessed and product preference recorded after the final measurement for each intervention.

RESULTS

Hypromellose drops caused an increase in total higher order aberrations (p=<0.01 in normal and dry eyes) and a reduction in Strehl ratio (normal eyes: p=<0.01, dry eyes p=0.01) immediately after instillation. There were no significant differences between normal and self-diagnosed dry eyes for response to intervention and no improvement in visual quality or reduction in higher order aberrations after 60 min. Differences in comfort levels failed to reach statistical significance.

CONCLUSION

Combining treatments does not offer any benefit over individual treatments in self-diagnosed dry eyes and no individual intervention reached statistical significance. Symptomatic subjects with dry eye and no corneal staining reported an improvement in comfort after using lubricants.

The impact of dry eye disease on visual performance while driving

PURPOSE

A specific simulator was used to assess the driving visual performance in patients with dry eye disease (DED) and to determine clinical predictors of visual impairments while driving.

DESIGN

Prospective case-control study.

METHODS

The study was conducted in the Center for Clinical Investigation of Quinze-Vingts National Ophthalmology Hospital, Paris, France. Twenty dry eye patients and 20 age- and sex-matched control subjects were included. Vision-related driving ability was assessed using a specific driving simulator displaying randomly located targets with a progressive increase in contrast to be identified. Other examinations included clinical examinations, serial measurements of corneal higher-order aberrations (HOAs), and vision-related quality-of-life questionnaire (Ocular Surface Disease Index [OSDI]). Data collected during driving test (ie, the number of targets seen, their position, and the response time) were compared between groups and analyzed according to clinical data, aberration dynamics, and quality-of-life index.

RESULTS

The percentage of targets missed as well as average response time were significantly increased in DED patients as compared with controls (P < .01). More specifically, the visual function of DED patients was more impaired in specific situations, such as crossroad or roundabout approaches. In DED patients, the response time was found to positively correlate with the progression index for HOAs (P < .01) and with the OSDI "symptoms" subscale (P < .05).

CONCLUSIONS

Degradation of ocular optical qualities related to DED is associated with visual impairments during driving. This study objectively has demonstrated the impact of tear film-related aberration changes on activities of daily living in DED.

Effects of diquafosol tetrasodium administration on visual function in short break-up time dry eye

PURPOSE

To investigate the effect of diquafosol tetrasodium on tear and visual function in short break-up time (sBUT) dry eye (DE).

METHODS

This interventional nonrandomized comparative study involved 11 eyes in 11 patients with sBUT DE (symptom-positive sBUT group) and 13 eyes in 13 volunteers with BUT values ≤5 s without DE symptoms (symptom-negative sBUT group). Tear function was assessed by measuring BUT and Schirmer values. Serial measurements were made of visual acuities (using a functional visual acuity measurement system) and higher-order aberrations (using a wavefront sensor). The parameters were compared before and 1 month after diquafosol tetrasodium instillation. Any changes in symptomatology after administration were also recorded.

RESULTS

After diquafosol tetrasodium administration, BUT values tended to increase in the symptom-positive sBUT group (P=0.07) and significantly increased in the symptom-negative sBUT group (P<0.05). LogMAR functional, minimal, and maximal visual acuities and higher-order aberrations significantly decreased after diquafosol tetrasodium administration in the symptom-positive sBUT group (P<0.05), while there were no significant changes in these values in the symptom-negative sBUT group (P>0.05). Diquafosol tetrasodium administration provided relief of DE symptoms in 75% of patients in the symptom-positive sBUT group.

CONCLUSIONS

Diquafosol tetrasodium appeared to improve tear film stability and visual function in sBUT DE.

Punctal plugs versus artificial tears for treating dry eye: a comparative observation of their effects on contrast sensitivity

This study aimed to compare the effects of treatment with punctal plugs versus artificial tears on visual function and tear film stability for dry eye. A total of 56 consecutive eyes of 28 dry eye patients observed at our clinic from May to October in 2009 were divided into two groups. One group (32 eyes of 16 patients) was treated with artificial tears, and punctal plugs were used in the other group (24 eyes of 12 patients). A questionnaire was used in these patients before treatment and was repeated 2 weeks after treatment. Fluorescent staining for tear film break-up time (BUT), the Schirmer test I (STI), and contrast sensitivity was performed at the same time. The questionnaire indicated that all patients complained about the uncomfortable symptoms associated with dry eye. These symptoms were relieved after the application of artificial tears or punctal plugs, and there was no significant difference between these two groups. We found that the corneal fluorescent staining disappeared after treatment. The BUT was improved significantly after treatment in both groups, but the improvement was greater in patients who received punctal plugs than those that received artificial tears. There was no remarkable change in the STI in the artificial tears group, but a significant change was observed in the punctal plugs group. The contrast sensitivities were greatly improved in simulated daylight, night, and glare disability conditions after treatment with artificial tears and punctal plugs. However, the changes in contrast sensitivity did not significantly differ between groups. Both artificial tears and punctal plugs relieved dry eye symptoms, repaired corneal lesions, enhanced tear film stability, and improved contrast sensitivity. Punctal plugs could improve tear film stability and elongate the BUT better than artificial tears.

How to promote and preserve eyelid health

Disorders of the lacrimal functional unit are common in ophthalmological practice, with meibomian gland dysfunction, blepharitis, and dry eye forming a significant part of the general ophthalmologist’s practice. The eyelid and its associated structures form a complex organ designed to protect the fragile corneal surface and improve visual acuity. This organ is subject to a number of disorders, including meibomian gland dysfunction, dry eye syndrome, anterior blepharitis, allergic and dermatological conditions, and disorders associated with contact lens use. Although commonly described separately, disorders of the lacrimal function unit are better considered as a group of interacting pathologies that have inflammatory mediators as a central feature. Eyelid hygiene, in the sense of routine cleansing and massage of the eyelids, is well accepted in the management of many disorders of the eyelid. However, a broader concept of eyelid health may be appropriate, in which eyelid cleansing is but a part of a more complete program of care that includes screening and risk assessment, patient education, and coaching. The ophthalmologist has an important role to play in helping patients persist with routine eyelid care that may be long-term or lifelong. A number of preparations exist to make routine eyelid care both more effective and more pleasant, and might also improve compliance. Several such preparations have been devised, and are being assessed in clinical studies, and appear to be effective and preferred by patients over traditional soap and water or baby shampoo.

Future directions in non-invasive measurements of tear film surface kinetics

PURPOSE

To review the methods for dynamic, non-invasive, and objective assessment of tear film surface quality and to outline their current state-of-the-art and their future potential.

METHODS

Among the methods available, high-speed videokeratoscopy, lateral shearing interferometry, and dynamic wavefront sensing are being considered.

RESULTS

The principles of operations, their advantages and disadvantages, and limitations of each method are being outlined. The possible future directions of each method are also discussed.

CONCLUSIONS

To gain a better understanding of tear film, its structure and function, it is essential to combine macroimaging technologies with those focusing on tear film microstructure. In this way, one can envisage a clinical device that could help, in future, early diagnosis of dry eye syndrome and development of better materials for contact lenses and eye lubricants.

The relation between visual performance and clinical ocular manifestations in Stevens-Johnson syndrome

PURPOSE

To investigate the relation between visual function, clinical findings, and visual symptoms in Stevens-Johnson syndrome (SJS) and to compare the results with Sjögren syndrome (SS) patients and normal subjects.

DESIGN

Cross-sectional comparative study.

METHODS

One hundred fifteen eyes of 59 consecutive patients with SJS and toxic epidermal necrolysis (TEN), 208 eyes of 104 healthy normal subjects, and 132 eyes of 66 SS patients were investigated in this multicenter study. All study subjects underwent tear function and ocular surface examinations, Landolt and functional visual acuity examinations, and the Japanese version of the NEI VFQ-25 (National Eye Institute Visual Function Questionnaire).

RESULTS

The mean ocular surface grading scores were significantly higher and the mean score of all 12 NEI VFQ subscales was significantly lower in the SJS patients compared to the SS patients and the normal subjects (P < .05). The conventional and functional logarithm of minimal angle of resolution (logMAR) visual acuities in SJS patients with minimal corneal complications were significantly higher and the mean total composite NEI VFQ scores were lower compared to SS patients. The conventional and functional logMAR visual acuities and the mean ocular surface grading scores in SJS with aqueous deficiency were significantly higher and the mean total composite NEI VFQ scores were lower compared to SS patients. Strong correlations between best-corrected logMAR functional visual acuities and either ocular surface grading scores or the composite NEI VFQ-25 scores were observed.

CONCLUSIONS

The functional visual acuity examination reflects the severity of clinical ocular surface findings and vision-related quality of life more than the standard conventional visual acuity in SJS.

Passive smoking as a risk factor of dry eye in children

Purpose. Adult active smoking is a risk factor for dry eye. We hypothesize that passive smoking in children can also produce the same effects. Methods. We included 112 school children presenting with eye discomfort. Assessment of eye dryness and its severity levels depending on symptoms of dry eye, visual symptoms, tear breakup time (TBUT), Schirmer-1 test, and corneal fluorescein staining were done for all of them. Exposure to cigarette smoking was assessed by history-taking and urinary cotinine levels. Results. Dry eye was found in 80/112 children. Passive smoking was documented in 76/112 children. Number of cigarettes to which the child was exposed per day and the duration of exposure to passive smoking were significantly higher in children with dry eye compared to those without. Urinary cotinine, and cotinine/creatinine ratio (CCR) was significantly higher in children with dry eye compared to those without dry eye. Multiregression analysis showed that the most important determinants of dry eye were CCR and number of cigarettes/day. Conclusion. Passive smoking represents a significant risk factor of dry eye in children comparable to that shown with active adult smoking. Male children are more prone to this effect.

Effects of preservative-free tafluprost on tear film osmolarity, tolerability, and intraocular pressure in previously treated patients with open-angle glaucoma

Purpose

To compare the effects on tolerability, tear osmolarity, and intraocular pressure (IOP)-lowering effect of switching from benzalkonium chloride (BAK) containing prostaglandin analog (PGA) latanoprost to preservative-free tafluprost.

Patients and methods

Thirty patients with open-angle glaucoma (N = 60 eyes), 26 women (87%) and four men (13%) aged 64.1 (SD 14.1) years, showing abnormal values of tear osmolarity, corneal fluorescein staining, tear film break-up time (TBUT), or subjective discomfort with current latanoprost treatment were included. After tear osmolarity (TearLab™ Osmolarity System), TBUT, corneal fluorescein staining, and baseline IOP (Goldmann tonometer) measurements and the completion of Ocular Surface Disease Index and Ocular Surface Symptoms in Glaucoma Scale questionnaires, patients were assigned to preservative-free tafluprost treatment. Measurements were repeated 2, 6 and 12 weeks after change of medication.

Results

No statistically significant differences in IOP were observed 2, 6, and 12 weeks after switching to preservative-free tafluprost. Mean IOP at baseline was 16.4 mmHg (SD 2.9), after 2 weeks 16.2 mmHg (2.8), after 6 weeks 16.2 (2.6), and after 12 weeks 16.3 mmHg (2.3). Mean tear osmolarity decreased significantly from 315.7 mOsm/L (SD 15.1) at baseline to 308.0 ± 14.4 mOsm/L (P = 0.002), 301.7 ± 14.5 mOsm/L (P < 0.001), and 302.0 ± 9.9 mOsm/L (P < 0.001) 2, 6, and 12 weeks after changing medication to preservative-free tafluprost, respectively. Tear osmolarity was lower in 37 eyes (61.7%) after 2 weeks, in 46 eyes (76.7%) after 6 weeks, and in 49 eyes (81.7%) after 12 weeks (P < 0.005; t-test). At baseline corneal fluorescein staining was observed in 43 eyes (71.7%), after 2 weeks in 34 eyes (56.7%), after 6 weeks in 12 eyes (20.0%), and after 12 weeks in 7 eyes (11.7%) (P < 0.005; McNemar test). Mean TBUT increased from 3.7 seconds (SD 1.1) at baseline to 4.1 seconds (SD 1.0) at week 2, 5.2 seconds (SD 1.5) at week 6, and 6.5 seconds (SD 1.5) at week 12 (P < 0.001; t-test). The number of patients expressing discomfort with latanoprost diminished from 30 (100%) at baseline, to 19 (63.3%) after week 2, and to 11 (36.6%) (P < 0.05; McNemar test) after 12 weeks.

Conclusion

Preservative-free tafluprost is better tolerated than BAK-containing latanoprost, showing lower tear osmolarity levels while maintaining effective IOP control.

The challenge of dry eye diagnosis

The currently available methods for the diagnosis of dry eye are still far from being perfect for a variety of reasons. This review attempts to highlight the advantages and disadvantages of both traditional tests (such as Schirmer’s test, break-up time and ocular surface staining) and innovative noninvasive procedures, including tear meniscus height measurement, corneal topography, functional visual acuity, tear interferometry, tear evaporimetry and tear osmolarity assessment.

Hyperosmolarity-mediated mitochondrial dysfunction requires Transglutaminase-2 in human corneal epithelial cells

Hyperosmolar-induced ocular surface cell death is a key mitochondria-mediated event in inflammatory eye diseases. Transglutaminase (TGM)-2, a cross-linking enzyme, is purported to mediate cell death, but its link to mitochondria is unclear. In the cornea, the integrity of the epithelial cells is important for maintaining transparency of the cornea and therefore functional vision. We evaluated the role of TGM-2 and its involvement in hyperosmolarity-stimulated mitochondrial cell death in human corneal epithelial (HCE-T) cells. HCE-T cell lines stably expressing either shRNA targeting TGM-2 (shTG) or scrambled shRNA (shRNA) were constructed. Hyperosmolar conditions reduced viability and increased mitochondrial depolarization in shRNA cells. However, hyperosmolarity failed to induce mitochondrial depolarization to the same extent in shTG cells. Transient overexpression of TGM-2 resulted in very high levels of TGM-2 expression in shTG and shRNA cells. In the case of shTG cells after overexpression of TGM-2, hyperosmolarity induced the same extent of mitochondrial depolarization as similarly treated shRNA cells. Overexpression of TGM-2 also elevated transamidase activity and reduced viability. It also induced mitochondrial depolarization, increased caspase-3/7 and -9 activity, and these increases were partially suppressed by pan-caspase inhibitor Z-VAD-FMK. Corneal epithelial apoptosis via mitochondrial dysfunction after hyperosmolar stimulation is partially dependent on TGM-2. This TGM-2-dependent mechanism occurs in part via caspase-3/7 and -9. Protection against mitochondrial stress in the ocular surface targeting TGM-2 may have important implications in the survival of cells in hyperosmolar stress.

Tear cytokine and chemokine analysis and clinical correlations in evaporative-type dry eye disease

PURPOSE

Inflammatory molecules have been demonstrated in the tear film of patients with severe dry eye disease (DED). However, little attention has been paid to the most frequent moderate forms of DED. This study analyzes tear cytokine levels and their clinical correlations in patients with moderate evaporative-type DED due to meibomian gland disease (MGD).

METHODS

Twenty three evaporative-type DED patients (46 eyes) of mild-to-moderate intensity and nine healthy subjects (18 eyes) were recruited. Two symptom questionnaires were self-answered and multiple DED-related clinical tests were performed. Unstimulated tears from each eye were isolated and were not pooled. Levels of 15 cytokines and chemokines were measured by multiplex bead analysis, compared with control levels, and correlated with clinical tests.

RESULTS

Fourteen out of the 15 molecules were reliably detected in 1 microl of unstimulated tears from DED patients. Epidermal growth factor (EGF), fractalkine/CX3CL1, interleukin (IL) 1-receptor antagonist (Ra), IL-8/CXCL8, interferon inducible protein (IP)-10/CXCL10, and vascular endothelial growth factor (VEGF) were found in 94%-100% of samples; IL-6 in 65% (significantly more detected in older patients); IL-1beta, interferon gamma (IFN-gamma), and IL-10 in 30%-48%; IL-17 in 13%; granulocyte macrophage colony stimulating factor (GM-CSF), IL-13, and tumor necrosis factor alpha (TNF-alpha) in 2%-9%; and IL-5 was never detected. EGF, fractalkine/CX3CL1, IL-1Ra, IP-10/CXCL10, and VEGF levels were significantly increased compared to normal controls. Pain was correlated with IL-6 and IL-8/CXCL8. Tear break-up time correlated inversely with IL1-Ra. Schirmer test and tear lysozyme levels negatively correlated with IL-1Ra, IL-8/CXCL8, fracktalkine/CX3CL1, IL-6, IP-10/CXCL10, and VEGF had the same tendency. Conjunctival staining correlated negatively with EGF and positively with IL-6.

CONCLUSIONS

In this sample of moderate evaporative-type DED patients, five inflammatory molecules were elevated. Fracktalkine was demonstrated to be present and elevated in tears in human DED. IL-1Ra, IL-6, IL-8/CXCL8, and EGF levels correlated with pain and with clinical parameters measuring tear stability, tear production or ocular surface integrity. These results suggest that inflammation plays a role not only in severe DED but also in moderate evaporative DED.

Measurement of the time course of optical quality and visual deterioration during tear break-up

PURPOSE

To compare changes in optical quality and visual performance that accompany tear break-up (TBU) during blink suppression.

METHODS

A three-channel optical system was developed that simultaneously measured refractive aberrations (Shack-Hartmann aberrometer), 20/40 letter contrast sensitivity (CS), and TBU (retroillumination, RI). Ten wearers of silicone hydrogel contact lenses were asked to keep one eye open for approximately 18 seconds, while CS, wavefront aberrations, and RI images were collected. The wavefront was reconstructed by zonal methods, and image quality was quantified with a series of metrics including RMS fit error. Novel metrics for quantifying TBU over the contact lens surface were developed by quantifying the contrast of the RI image and by using Fourier descriptors of the first Purkinje (PJ) image shape.

RESULTS

There was a full range of TBU over the lens surface, with four subjects showing TBU across the corneal center and one subject with TBU in the inferior peripheral pupil. Among the four subjects with central corneal TBU, RMS fit error, RI contrast, and PJ Fourier descriptors showed high correlation with CS (r(2) range, 0.9187-0.9414, 0.6261-0.975, and 0.4917-0.8986, respectively). Some of the general optical-quality metrics such as blur strength, neural sharpness, and area of modulation transfer function (MTF) also showed that change correlated with CS loss.

CONCLUSIONS

Optical metrics of tear quality and retinal image quality are associated with the decline in vision that occurs with TBU. The evidence supports the hypothesis that blurry vision symptoms reported by contact lens wearers are caused by poor quality of the retinal image due to TBU.

Dynamic wavefront aberrations and visual acuity in normal and dry eyes

PURPOSE

The aim was to study the dynamic properties of wavefront aberrations and visual acuity in normal and dry eyes.

METHODS

Thirty dry-eye patients and 27 normal subjects participated in this study. Multi-file mode of a Hartmann-Shack wavefront sensor was used to measure dynamic wavefront aberrations for a period of 45 seconds. Dynamic measurements of visual acuity (VA) were made for 150 seconds using a multi-functional VA tester. Standard deviation of the measurements (RMS or VA) over the testing period was used to estimate instability of the dynamic wavefront aberration and VA.

RESULTS

For most subjects, both wavefront aberration and VA changed over time and the instability varied substantially among individuals. Blink-dependent fluctuation in wavefront aberration or VA was observed for some dry-eye subjects. On average, the dry-eye group had greater instability than the normal group in either the higher order wavefront aberrations (t = 2.09, p = 0.03, for OD; t = 3.76, p = 0.001, for OS) or the VA (t = 2.09,p = 0.02, for OD; t = 204, p = 0.03, for OS). Instability of VA in the dry-eye group was significantly correlated with blink rate (r = 0.28, p = 0.02).

CONCLUSION

Dynamic changes in wavefront aberrations and VA are highly individual dependent, while the dry eye tends to be less stable than the normal eye. The results suggest that tear-film fluctuation might play a role in determining dynamic wavefront aberration and VA; however, contributions from other factors should not be overlooked. For dry eye, dynamic change in VA depends on blink rate.

Concept of functional visual acuity and its applications

Functional visual acuity (FVA) has been suggested to reflect an individual's performance in relation to certain daily activities involving visual tasks. The concept of FVA has been thought applicable to the detection of masked impairment of visual function in patients with dry eye who complain of decreased visual acuity despite normal conventional visual acuity. A stable tear-film layer over the surface of the cornea is essential for a smooth ocular surface and the formation of clear visual images. In dry eye, the ocular surface tends to dry out when normal blinking is suppressed during gazing, and patients with dry eye may have problems maintaining clear vision while gazing. The FVA measurement system is a device to measure changes in continuous visual acuity over time. Visual maintenance ratio (VMR) is the ratio between FVA and baseline visual acuity. FVA and VMR are indices for the assessment of functional vision. FVA has been thought applicable to the detection of changes in functional vision in relation to the tear film over the ocular surface. It may also be useful for the assessment of subjective visual complaints in diseases that do not involve dry eye.

Wavefront sensing and the dynamics of tear film

PURPOSE

To summarize our previous studies regarding the influence of tear-film dynamics on optical quality after blinking.

METHODS

Sequential higher-order aberration (HOA) measurements were performed by using a wavefront sensor. During the measurements, subjects were asked to blink every 10 seconds. The obtained aberration data were analyzed in the central 4-mm diameter for coma-like, spherical-like, and total HOAs up to the sixth-order Zernike polynomials.

RESULTS

Serial measurements of HOAs in healthy eyes showed variations even in clinically normal subjects and were classified into 4 groups by pattern: stable, small-fluctuation, sawtooth, and others. The sequential postblink change in HOAs after punctal plug insertion was quantitatively evaluated in a patient with dry eye who complained of paradoxical visual impairment with epiphora despite improvement of dry eye.

CONCLUSIONS

Wavefront sensing is a useful objective method to evaluate sequential changes of visual performance related to tear-film dynamics. Serial measurement of HOAs might show a relationship between tear dynamics and quality of vision clinically.

Noninvasive interference tear meniscometry in dry eye patients with Sjögren syndrome

PURPOSE

To compare noninvasive tear meniscus height (NI-TMH) using a tear interference device in normal subjects and dry eye patients with Sjögren syndrome (SS), and to investigate the applicability of this new method before and after the punctal occlusion procedure.

DESIGN

Prospective case control study.

METHODS

Tear meniscus was visualized noninvasively using a tear interference device (Tearscope plus, Keeler, Windsor, United Kingdom). Tear interference image was captured with digital video camera (SP-321, JFC Sales Plan Co, Tokyo, Japan) attached to the slit-lamp. Lower lid margin NI-TMH was measured using image analysis software. NI-TMH of 28 eyes from 17 normal subjects and 46 eyes from 27 aqueous tear deficiency (ATD) dry eye patients with SS were compared. The change of NI-TMH three weeks after the successful punctal occlusion was examined in 11 eyes of eight dry eye subjects.

RESULTS

Tear meniscus was well visualized with the tear interference device in all cases. Lower lid margin NI-TMH was 0.22 +/- 0.065 mm in normal subjects, and 0.13 +/- 0.042 mm in SS subjects, respectively (P < .0001). After the punctal occlusion, lower lid margin NI-TMH increased significantly from 0.12 +/- 0.026 mm to 0.42 +/- 0.21 mm (P = .001).

CONCLUSIONS

NI-TMH was substantially lower in SS subjects and also significantly improved after punctal occlusion. This method is expected to be helpful in the diagnosis and in the evaluation of the efficacy of punctal occlusion in ATD dry eyes such as SS.

The Definition and Classification of Dry Eye Disease: Report of the Definition and Classification Subcommittee of the International Dry Eye Workshop (2007)

The aim of the DEWS Definition and Classification Subcommittee was to provide a contemporary definition of dry eye disease, supported within a comprehensive classification framework. A new definition of dry eye was developed to reflect current understanding of the disease, and the committee recommended a three-part classification system. The first part is etiopathogenic and illustrates the multiple causes of dry eye. The second is mechanistic and shows how each cause of dry eye may act through a common pathway. It is stressed that any form of dry eye can interact with and exacerbate other forms of dry eye, as part of a vicious circle. Finally, a scheme is presented, based on the severity of the dry eye disease, which is expected to provide a rational basis for therapy. These guidelines are not intended to override the clinical assessment and judgment of an expert clinician in individual cases, but they should prove helpful in the conduct of clinical practice and research.

The Brilliant Beauty of the Eye

PURPOSE

Light reflex from the cornea and tear film as contributors to beautiful eyes ("eye sparkling") are reviewed.

METHODS

A systematic literature review was conducted using "Purkinje-Sanson image," "corneal light reflex," "corneal topography," "corneal wavefront aberration," and "tear interference image" as search terms.

RESULTS

Articles on corneal surface regularity and stability and tear interferometry of the precorneal tear lipid layer were reviewed. PS-1 image, that is light reflex from the cornea and tear film, is widely used in practical ophthalmic examination.

CONCLUSION

To achieve a brilliant beauty of the eye ("eye sparkling"), it is important that the tear film (aqueous layer) surface is smooth and stable with adequate tear volume and that the tear lipid layer is present in adequate thickness.