Inner eyelid surface temperature as a function of warm compress methodology

Design of a Subtarsal Ultrasonic Transducer for Mild Hyperthermia Treatment of Dry Eye Disease

Dry eye disease is a disorder of the ocular surface that causes pain and low vision in a significant portion of the adult population. A common cause is obstructive Meibomian gland dysfunction, whereby the Meibomian glands secrete abnormal meibum with a melting point elevated by 3°C-4°C; hence, hyperthermia is the typical treatment. A design is proposed for an ultrasound hyperthermia device made of a transducer contained inside a contact lens with an internal air gap. The transducer heats the posterior of the tarsus, and the air gap provides an air backing to the transducer, preventing direct heating of the cornea. A prototype device was built, and hyperthermia experiments were performed on a porcine subject in vivo. A therapeutic temperature rise of 5°C-7°C was achievable in 10-15 min. The temperature of the cornea did not rise more than 2°C during any of the experiments.

Comparison of Self-applied Heat Therapy for Meibomian Gland Dysfunction

PURPOSE

To compare the effects on ocular temperature, lipid layer grade, tear film stability, and tear meniscus height after a single application of two commercially available warm compresses in mild-to-moderate dry eye and to report participant treatment preference.

METHODS

Forty-one subjects with mild-to-moderate dry eye symptoms were enrolled in a randomized, paired-eye, investigator-masked trial. Heat was applied simultaneously to one eye (randomized) with a portable eye mask (EyeGiene) and to the contralateral eye with a microwave-heated flaxseed eye bag (MGDRx Eye Bag). Outer and inner eyelid temperatures, tear film lipid layer grade (LLG), and noninvasive tear film breakup time (NIBUT) were measured at baseline and immediately after 10 minutes of device application.

RESULTS

Outer and inner eyelid temperatures, LLG, and NIBUT did not differ before treatment between eyes assigned to eye mask and eye bag therapy. All measurements were significantly increased from baseline, after warming with both devices (all p < 0.05). Outer and inner eyelid temperature changes were significantly greater with the eye bag than with the eye mask (outer eyelid, +3.5 ± 1.0°C vs. +2.4 ± 0.8°C; inner eyelid, +3.5 ± 1.0°C vs. +2.5 ± 0.9°C; all p < 0.001), although there was no significant difference in LLG and NIBUT improvement between treatments (all p > 0.05). A majority of subjects (78%) preferred the application of heat with the eye bag over the eye mask.

CONCLUSIONS

Both the EyeGiene mask and the MGDRx Eye Bag are convenient eyelid warming devices that result in clinically and statistically significant increases in NIBUT and LLG in patients with mild-to-moderate dry eye symptoms. The MGDRx Eye Bag is more effective in raising ocular temperature and is the preferred treatment method among subjects.

All Warm Compresses Are Not Equally Efficacious

PURPOSE

To investigate which warm compress (WC) methods used in a small case series are the most effective in providing heat to the inner eyelids for the supplemental treatment of meibomian gland dysfunction.

METHODS

Inclusion criteria included the following: 18 years or older and willingness to participate in the study, no current ocular inflammation/disease, and no ocular surgery within the last 6 months. Five patients were fully consented and enrolled. Various forms of contact and noncontact WC heating methods (dry, wet/moist, and chemically activated dry heat) were tested. A paired contralateral design was used; each subject had a heated test eye and an unheated control eye. For both test and control eyes, the temperature of the external upper, external lower, and internal lower lids was measured at baseline and every 2 minutes for 10 minutes during application. Each participant underwent each of the eight treatments under study. Microwaved compresses were heated to 47 ± 1.0°C; two compresses were self-heating and thus not under investigator control.

RESULTS

The mean (± SD) age of the patients was 42.2 (± 20.3) years. Out of the eight methods tested, the bundled wet/moist towel method was the only compress that elevated the temperature of all three lid surfaces (external upper, external lower, and internal lower lids) to 40°C or higher. The chemically activated EyeGiene, MGDRx EyeBag, and MediBeads compresses resulted in the lowest temperature increase at the inner palpebral surface.

CONCLUSIONS

The Bundle method, although the most labor intensive, increased lid temperatures above therapeutic levels, as reported in the literature, for all measured sections during the WC application. As such, this method of WC application can be recommended for supplemental at-home therapy for meibomian gland dysfunction and any condition requiring that therapeutic heat of 40°C be administered to the meibomian glands.

Medical management of blepharitis

PURPOSE OF REVIEW

Blepharitis is one of the most common ocular pathologies encountered in the clinical setting. Despite its prevalence, successful treatment is often difficult. The purpose of this review is to provide an update on the medical management of blepharitis.

RECENT FINDINGS

The available treatment options for blepharitis have expanded rapidly in recent years. Eyelid hygiene remains the foundation of most treatment regimens, but the addition of topical and oral antibiotics, steroids, and calcineurin inhibitors is showing promising results. Dietary considerations and interventional procedures may also play a role in the future of blepharitis management.

SUMMARY

Although a curative therapy for blepharitis is unlikely in the near future, several novel treatment options may result in better control of this chronic condition.

Temperature profiles of patient-applied eyelid warming therapies

PURPOSE

To compare temperature profile characteristics (on and off eye) of two patient-applied heat therapies for meibomian gland dysfunction (MGD): an eye mask containing disposable warming units (EyeGiene(®)) and a microwave-heated flaxseed eye bag(®) (MGDRx EyeBag(®)).

METHODS

In vitro evaluation: surface temperature profiles of activated eye masks and heated eye bags(®) (both n=10), were tracked every 10s until return to ambient temperature. Heat-transfer assessment: outer and inner eyelid temperature profiles throughout the eye mask and eye bag(®) treatment application period (10min) were investigated in triplicate. The devices were applied for 12 different time intervals in a randomised order, with a cool-down period in between to ensure ocular temperatures returned to baseline. Temperature measurements were taken before and immediately after each application.

RESULTS

In vitro evaluation: on profile, the eye bag(®) surface temperature peaked earlier (0±0 s vs. 100±20 s, p<0.001), cooled more slowly and displayed less variability than the eye mask (all p<0.05). Heat-transfer assessment: the eye bag(®) effected higher peak inner eyelid temperatures (38.1±0.4°C vs. 37.4±0.2°C, p=0.04), as well as larger inner eyelid temperature increases over the first 2 min, and between 9 and 10 min (all p<0.05).

CONCLUSIONS

The eye bag(®) surface temperature profile displayed greater uniformity and slower cooling than the eye mask, and was demonstrated to be significantly more effective in raising ocular temperatures than the eye mask, both statistically and clinically. This has implications for MGD treatment, where the melting points of meibomian secretions are likely to be higher with increasing disease severity.

Effects of Eyelid Warming Devices on Tear Film Parameters in Normal Subjects and Patients with Meibomian Gland Dysfunction

PURPOSE

To evaluate the effects of commercially available eyelid warming devices on ocular temperatures, tear film function, and meibomian glands in normal subjects and patients with meibomian gland dysfunction (MGD).

METHODS

Ten healthy volunteers were enrolled to evaluate the effects of a single warming and of repeated warming for 2 weeks. Ten MGD patients were enrolled for evaluation of repeated warming over 1 month. Two non-wet (Azuki no Chikara, Eye Hot R) and three wet (hot towel, Hot Eye Mask, Memoto Este) devices were compared in a masked manner. Visual analog scale (VAS) score for ocular symptoms, tear film breakup time (TFBUT), meibum grade, temperatures (eyelid skin, tarsal conjunctiva, central cornea), Schirmer test value, and meibomian gland area were measured before and after warming application.

RESULTS

The single application of the five warming devices improved the VAS score, TFBUT, and ocular temperatures. In the repeated warming application, Azuki no Chikara as a representative non-wet warming device induced a stable and significant improvement in TFBUT and increased the tarsal conjunctival temperature and meibomian gland area in both normal subjects and MGD patients. It also improved meibum grade in MGD patients.

CONCLUSION

Our results suggest that repeated eyelid warming with a non-wet device improves tear film function in normal individuals and may have beneficial effects on both tear film and meibomian gland function in MGD patients.

[Intraductal meibomian gland probing for the treatment of blepharitis]

OBJECTIVE

To describe the results of the meibomian gland probing as a treatment of severe posterior blepharitis.

METHODS

Prospective, longitudinal study of patients with signs and symptoms of severe posterior blepharitis, who were treated with meibomian gland probing in Centro Oftalmológico Interlomas (CENOFI). A total of 16 patients were included, 62.5% female and 32.5% male, diagnosed with severe posterior blepharitis. Treatment was performed in one eye. The time of rupture of the tear film was evaluated, using a subjective scale of 0-10 photophobia, the improvement in pain and visual acuity was measured before the procedure, and at one week and 6 months after.

RESULTS

All the patients showed a statistically significant improvement in all 4 variables al 6 months. There were no complications.

DISCUSSION

The dysfunction of the meibomian glands is a common reason for ophthalmology consulting. The study describes the results obtained by performing an intraductal survey, which was shown to be safe and effective in 100% of the sample.

CONCLUSIONS

It can be concluded from this study that meibomian gland probing is an effective and promising treatment for blepharitis resistant to conservative treatment.

Effects of topical loteprednol etabonate on tear cytokines and clinical outcomes in moderate and severe meibomian gland dysfunction: randomized clinical trial

PURPOSE

To assess tear cytokine levels and clinical outcomes in moderate and severe meibomian gland dysfunction (MGD) after 2 months of treatment with topical loteprednol etabonate and eyelid scrubs with warm compresses vs eyelid scrubs with warm compresses alone.

DESIGN

Randomized controlled trial.

METHODS

Patients with moderate and severe MGD were randomized into 2 groups: topical loteprednol etabonate and eyelid scrubs with warm compresses (Group I, 34 eyes) or eyelid scrubs with warm compresses (Group II, 36 eyes). We evaluated cytokine levels, tear film break-up time (TBUT), corneal and conjunctival fluorescein staining, biomicroscopic examination of lid margins and meibomian glands, and the Ocular Surface Disease Index before initiating treatment and 1 month and 2 months after treatment.

RESULTS

There were significant decreases in the levels of interleukin (IL)-6, IL-8, and IL-1β in Group I, and IL-6 and IL-8 in Group II. Moreover, the observed decreases of these cytokines in Group I were attributed to a remarkable decrease between treatment and 1 month after treatment. In Group I, there were improvements in all of the clinical outcomes, with prominent improvement in TBUT, corneal and conjunctival fluorescein staining, and meibum quality after 1 month of treatment, compared with Group II. An improvement in meibomian gland expressibility and MGD stage reduction were more remarkable in Group I.

CONCLUSIONS

Topical loteprednol etabonate and eyelid scrubs with warm compresses were tolerated and efficacious for the treatment of moderate and severe MGD. We suggest that such beneficial effects could manifest after 1 month.

Randomised masked clinical trial of the MGDRx EyeBag for the treatment of meibomian gland dysfunction-related evaporative dry eye

Background/aims

To investigate the efficacy and safety of the MGDRx EyeBag (The Eyebag Company, Halifax, UK) eyelid warming device.

Methods

Twenty-five patients with confirmed meibomian gland dysfunction (MGD)-related evaporative dry eye were enrolled into a randomised, single masked, contralateral clinical trial. Test eyes received a heated device; control eyes a non-heated device for 5 min twice a day for 2 weeks. Efficacy (ocular symptomology, non-invasive break-up time, lipid layer thickness, osmolarity, meibomian gland dropout and function) and safety (visual acuity, corneal topography, conjunctival hyperaemia and staining) measurements were taken at baseline and follow-up. Subsequent patient device usage and ocular comfort was ascertained at 6 months.

Results

Differences between test and control eyes at baseline were not statistically significant for all measurements (p>0.05). After 2 weeks, statistically significant improvements occurred in all efficacy measurements in test eyes (p<0.05). Visual acuity and corneal topography were unaffected (p>0.05). All patients maintained higher ocular comfort after 6 months (p<0.05), although the benefit was greater in those who continued usage 1–8 times a month (p<0.001).

Conclusions

The MGDRx EyeBag is a safe and effective device for the treatment of MGD-related evaporative dry eye. Subjective benefit lasts at least 6 months, aided by occasional retreatment.

Trial registration number

NCT01870180.

Longitudinal changes in tear fluid lipidome brought about by eyelid-warming treatment in a cohort of meibomian gland dysfunction

Meibomian gland dysfunction (MGD) is a leading cause of evaporative dry eye and ocular discomfort characterized by an unstable tear film principally attributed to afflicted delivery of lipids to the ocular surface. Herein, we elucidated longitudinal tear lipid alterations associated with disease alleviation and symptom improvement in a cohort of MGD patients undergoing eyelid-warming treatment for 12 weeks. Remarkably, eyelid-warming resulted in stark reductions in lysophospholipids (P < 0.001 for lyso-plasmalogen phosphatidylethanolamine, lysophosphatidylcholine, and lysophosphatidylinositol), as well as numerous PUFA-containing diacylglyceride species in tears, accompanied by significant increases in several PUFA-containing phospholipids. These changes in tear lipidomes suggest that eyelid-warming leads to diminished activity of tear phospholipases that preferentially target PUFA-containing phospholipids. In addition, treatment led to appreciable increases (P < 0.001) in O-acyl-ω-hydroxy-FAs (OAHFAs), which are lipid amphiphiles critical to the maintenance of tear film stability. Longitudinal changes in the tear lipids aforementioned also significantly (P < 0.05) correlated with reduced rate of ocular evaporation and improvement in ocular symptoms. The foregoing data thus indicate that excess ocular surface phospholipase activity detrimental to tear film stability could be alleviated by eyelid warming alone without application of steroids and identify tear OAHFAs as suitable markers to monitor treatment response in MGD.

Antievaporative mechanism of wax esters: implications for the function of tear fluid

The tear film lipid layer (TFLL) is considered to act as an evaporation barrier and to maintain the tear film intact between blinks. In vitro methods have, however, failed to reproduce this evaporation-retarding effect. Wax esters (WEs) are a major component of the TFLL. Close to their bulk melting temperature, WEs have been found to retard the evaporation of water, but the nature of this mechanism has remained unclear. We studied the interfacial organization of WE films by measuring their isochors and isotherms and evaporation-retarding effect, and we imaged these films by Brewster angle microscopy (BAM). Behenyl palmitoleate (BP) was used as a representative WE because it resembles the WEs found in meibum. At low temperatures, BP forms solid monolayer crystals in which the molecules are organized in a bulk-like extended conformation. Within approximately 3 °C below the bulk melting temperature, these solid monolayer domains coexist with a fluid monolayer film. At temperatures above the bulk melting temperature, BP forms a completely fluid monolayer in which the molecules are in a hairpin conformation. A fluid hairpin monolayer of BP does not significantly retard evaporation, whereas a solid monolayer decreases evaporation by >50%. The results provide a molecular-level rationale for the evaporation-retarding properties of WEs close to their melting temperature.

Effect of a commercially available warm compress on eyelid temperature and tear film in healthy eyes

PURPOSE

To evaluate eyelid temperature change and short-term effects on tear film stability and lipid layer thickness in healthy patients using a commercially available warm compress (MGDRx EyeBag) for ophthalmic use.

METHODS

Eyelid temperature, noninvasive tear film breakup time (NITBUT), and tear film lipid layer thickness (TFLLT) of 22 healthy subjects were measured at baseline, immediately after, and 10 minutes after application of a heated eyebag for 5 minutes to one eye selected at random. A nonheated eyebag was applied to the contralateral eye as a control.

RESULTS

Eyelid temperatures, NITBUT, and TFLLT increased significantly from baseline in test eyes immediately after removal of the heated eyebag compared with those in control eyes (maximum temperature change, 2.3 ± 1.2 °C vs. 0.3 ± 0.5 °C, F = 20.533, p < 0.001; NITBUT change, 4.0 ± 2.3 seconds vs. 0.4 ± 1.7 seconds, p < 0.001; TFLLT change, 2.0 ± 0.9 grades vs. 0.1 ± 0.4 grades, Z = -4.035, p < 0.001). After 10 minutes, measurements remained significantly higher than those in controls (maximum temperature change, 1.0 ± 0.7 °C vs. 0.1 ± 0.3 °C, F = 14.247, p < 0.001; NITBUT change, 3.6 ± 2.1 seconds vs. 0.1 ± 1.9 seconds, p < 0.001; TFLLT change, 1.5 ± 0.9 vs. 0.2 ± 0.5 grades, Z = -3.835, p < 0.001). No adverse events occurred during the study.

CONCLUSIONS

The MGDRx EyeBag is a simple device for heating the eyelids, resulting in increased NITBUT and TFLLT in subjects without meibomian gland dysfunction that seem to be clinically significant. Future studies are required to determine clinical efficacy and evaluate safety after long-term therapy in meibomian gland dysfunction patients.

[Meibomian gland dysfunction: a comparative study of modern treatments]

PURPOSE

To evaluate a thermal pulsation treatment compared to a warming eyelid device for the management of meibomian gland dysfunction.

METHODS

Thirty patients were randomized into two groups: the first had a treatment with MeiboPatch(®) on a daily basis for three months while the second had a single treatment with LipiFlow(®). The evaluation focused on a classical approach but also on a modern approach of the ocular surface (interferometry lipid layer LipiView(®)), analysis of the tear film by Oquas(®) (osmolarity by TearLab(®)) before treatment, then a month and three months later.

RESULTS

Both treatments proved to be effective with almost three times more functional meibomian glands at 3 months in the LipiFlow group and almost twice more in the MeiboPatch group (P<0.05) but the LipiFlow allows a more rapid improvement at the first month of treatment. Functional scores and classic exploration of the ocular surface except the Schirmer test also undergo a significant improvement in both groups after three months of treatment.

CONCLUSION

The combination of heat applied to the inner eyelid surface, together with simultaneous expression of the glands, during a single 12-minute treatment shows to be highly effective in treating cases of meibomian gland disease. Whilst results were excellent, and continued lid hygiene remains advised, the benefit of being able to simultaneous address potential compliance issues relating to ongoing treatment is significant. The convenience of a single 12-minute treatment versus an ongoing daily heating regime was shown to be highly desirable and a welcome relief in our patients' busy lifestyles.

Warm compresses and the risks of elevated corneal temperature with massage

PURPOSES

To quantify the changes in corneal temperature resulting from intensive warm compress (WC) application with minimal pressure and to review the significance of these changes within the context of the peer-reviewed literature.

METHODS

WC were applied intensively and unilaterally at 45 ± 0.5°C for 30 minutes with the contralateral eye serving as a control. Outer upper eyelid and central corneal surface temperatures were measured using an Infrared pyrometer at baseline. The WC were removed for repeat measurements of the outer upper eyelid surface and central corneal temperatures every 2 minutes and replaced with a new WC heated to 45 ± 0.5°C. Lid and corneal temperatures were monitored for 10 minutes after the final WC application.

RESULTS

The mean age of the subjects was 37.1 ± 15.0 years (n = 12). The mean maximum outer upper lid temperature of 42.2 ± 1.3°C was reached after 6 minutes. The mean maximum corneal temperature of 39.4 ± 0.7°C was reached after 8 minutes of heating. The control eye showed no significant change in temperature from baseline throughout the experimental period.

CONCLUSIONS

These data show that WC use for lid warming, even when only minimal contact pressure is applied, also transfers significant heat to the cornea. Corneal temperatures reach peak temperature after about 8 minutes of WC application. Recent reports discussing the increased potential for transient and long-term corneal molding subsequent to the heat and pressure of WC application are briefly reviewed.

Evaluation of the ocular tolerance of a novel eyelid-warming device used for meibomian gland dysfunction

PURPOSE

Obstructive meibomian gland dysfunction (MGD) frequently induces a chronic complaint with various symptoms related to dry eye and discomfort. Previous research indicates a pivotal role for heat therapy for melting the meibum as part of any successful management plan, but delivery of constant temperature during treatment is vital. This study evaluated the performance of a novel device designed to deliver controlled, latent, moist heat to the eyelids and surrounding area.

METHODS

The signs, symptoms and ocular temperature of 25 normal subjects (M8, F17; age 29.2±5.7 years) were recorded before and after a 10min application of the Blephasteam(®) device. Ocular temperature (non-invasive ocular thermography; A40 Flir, UK), tear film stability (NIBUT), intra-ocular pressure (IOP), and ocular surface staining and hyperaemia were recorded. Results were checked for normality and compared using paired t-tests.

RESULTS

Temperatures in both eyelids were significantly greater after device application (upper +1.7±0.9°C; lower +2.1±0.7°C, p<0.0005). Bulbar conjunctival hyperaemia significantly decreased after treatment (p<0.005), but limbal and palpebral hyperaemia remained similar (p=0.33 and p=0.11, respectively). Ocular surface staining (p=0.74) and tear film stability (p=0.12) were unchanged in this normal cohort, and there was no significant change in IOP (13.8±2.0mmHg vs 12.9±2.2mmHg; p=0.092).

CONCLUSIONS

The Blephasteam(®) device provides effective levels of warming that would be sufficient to melt meibum, and no adverse ocular responses were recorded in this cohort, indicating that this is a safe device. Interestingly, even in this normal cohort, ocular surface redness appears less after treatment.

Interventions for chronic blepharitis

BACKGROUND

Blepharitis, an inflammatory condition associated with itchiness, redness, flaking, and crusting of the eyelids, is a common eye condition that affects both children and adults. It is common in all ethnic groups and across all ages. Although infrequent, blepharitis can lead to permanent alterations to the eyelid margin or vision loss from superficial keratopathy (abnormality of the cornea), corneal neovascularization, and ulceration. Most importantly, blepharitis frequently causes significant ocular symptoms such as burning sensation, irritation, tearing, and red eyes as well as visual problems such as photophobia and blurred vision. The exact etiopathogenesis is unknown, but suspected to be multifactorial, including chronic low-grade infections of the ocular surface with bacteria, infestations with certain parasites such as demodex, and inflammatory skin conditions such as atopy and seborrhea. Blepharitis can be categorized in several different ways. First, categorization is based on the length of disease process: acute or chronic blepharitis. Second, categorization is based on the anatomical location of disease: anterior, or front of the eye (e.g. staphylococcal and seborrheic blepharitis), and posterior, or back of the eye (e.g. meibomian gland dysfunction (MGD)). This review focuses on chronic blepharitis and stratifies anterior and posterior blepharitis.

OBJECTIVES

To examine the effectiveness of interventions in the treatment of chronic blepharitis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 1), MEDLINE (January 1950 to February 2012), EMBASE (January 1980 to February 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We searched the reference lists of included studies for any additional studies not identified by the electronic searches. There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 9 February 2012.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-randomized controlled trials (CCTs) in which participants were adults aged 16 years or older and clinically diagnosed with chronic blepharitis. We also included trials where participants with chronic blepharitis were a subset of the participants included in the study and data were reported separately for these participants. Interventions within the scope of this review included medical treatment and lid hygiene measures.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed search results, reviewed full-text copies for eligibility, examined risk of bias, and extracted data. Data were meta-analyzed for studies comparing similar interventions and reporting comparable outcomes with the same timing. Otherwise, results for included studies were summarized in the text.

MAIN RESULTS

There were 34 studies (2169 participants with blepharitis) included in this review: 20 studies (14 RCTs and 6 CCTs) included 1661 participants with anterior or mixed blepharitis and 14 studies (12 RCTs and 2 CCTs) included 508 participants with posterior blepharitis (MGD). Due to the heterogeneity of study characteristics among the included studies, with respect to follow-up periods and types of interventions, comparisons, and condition of participants, our ability to perform meta-analyses was limited. Topical antibiotics were shown to provide some symptomatic relief and were effective in eradicating bacteria from the eyelid margin for anterior blepharitis. Lid hygiene may provide symptomatic relief for anterior and posterior blepharitis. The effectiveness of other treatments for blepharitis, such as topical steroids and oral antibiotics, were inconclusive.

AUTHORS' CONCLUSIONS

Despite identifying 34 trials related to treatments for blepharitis, there is no strong evidence for any of the treatments in terms of curing chronic blepharitis. Commercial products are marketed to consumers and prescribed to patients without substantial evidence of effectiveness. Further research is needed to evaluate the effectiveness of such treatments. Any RCT designed for this purpose should separate participants by type of condition (e.g. staphylococcal blepharitis or MGD) in order to minimize imbalances between groups (type I errors) and to achieve statistical power for analyses (prevent type II errors). Medical interventions and commercial products should be compared with conventional lid hygiene measures, such as warm compresses and eyelid margin washing, to determine effectiveness, as well as head-to-head to show comparative effectiveness between treatments. Outcomes of interest should be patient-centered and measured using validated questionnaires or scales. It is important that participants be followed long-term, at least one year, to assess chronic outcomes properly.

Meibomian gland therapeutic expression: quantifying the applied pressure and the limitation of resulting pain

OBJECTIVES

The purposes of this study were to determine (1) the pressure required to express the first nonliquid material from nonfunctional lower lid meibomian glands, (2) the pressure required to evacuate all of the expressible material from the glands (simulating the authors' methodology for therapeutic meibomian gland expression), and (3) the level of pain associated with these procedures.

METHODS

All patients (n=28) were recruited from those presenting for ocular examinations at a single practice. Custom instrumentation exerting pressures from 1.0 to 150.0 psi was developed to quantify the pressure applied during expression. The instrument was applied to the inner surface of the lower lid. The lid was then compressed between the thumb and the contact surface of the instrument. The applied pressure was displayed on a digital meter. The first procedure evaluated the pressure required to obtain the first nonliquid material from nonfunctional glands. The second evaluated the pressure required for evacuating all expressible gland contents. The pain response was monitored throughout the procedure.

RESULTS

The pressure to obtain the first nonliquid material ranged from 5 to 40 psi (mean=16.1±8.2 psi) and for the evacuation of expressible contents, from 10 to 40 psi (mean=25.6±11.4 psi). Only 7% of the patients could tolerate the pressure necessary to administer complete therapeutic expression along the entire lower eyelid.

CONCLUSIONS

Forces of significant magnitude are required for therapeutic expression. Pain is the limiting factor for the conduct of this treatment.

Thresholds for thermal damage to normal tissues: an update

The purpose of this review is to summarise a literature survey on thermal thresholds for tissue damage. This review covers published literature for the consecutive years from 2002-2009. The first review on this subject was published in 2003. It included an extensive discussion of how to use thermal dosimetric principles to normalise all time-temperature data histories to a common format. This review utilises those same principles to address sensitivity of a variety of tissues, but with particular emphasis on brain and testis. The review includes new data on tissues that were not included in the original review. Several important observations have come from this review. First, a large proportion of the papers examined for this review were discarded because time-temperature history at the site of thermal damage assessment was not recorded. It is strongly recommended that future research on this subject include such data. Second, very little data is available examining chronic consequences of thermal exposure. On a related point, the time of assessment of damage after exposure is critically important for assessing whether damage is transient or permanent. Additionally, virtually no data are available for repeated thermal exposures which may occur in certain recreational or occupational activities. For purposes of regulatory guidelines, both acute and lasting effects of thermal damage should be considered.

A novel thermodynamic treatment for meibomian gland dysfunction

PURPOSE

To evaluate a novel thermodynamic treatment for obstructive meibomian gland dysfunction (MGD).

MATERIALS AND METHODS

Fourteen adult subjects (10 females, 4 males, mean age = 54.2 ± 9.6 yr) were recruited in a multi-center, feasibility clinical trial in Durham and Cary, North Carolina and Boston, Massachusetts. Inclusion criteria included: previous diagnosis of moderate to severe dry eye; dry eye symptoms for at least three months prior; daily topical lubricant use; and evidence of meibomian gland (MG) obstruction in the central five glands of both eyes lower eyelids. Exclusion criteria included: history of recent acute or chronic ocular inflammation or infection and lid surface abnormalities affecting lid function. The treatment: the device heats the palpebral surface of upper and lower eyelids while simultaneously applying graded pulsatile pressure to the outer eyelid for 12 min, thereby expressing the MGs during heating. One eye was randomly selected to undergo additional manual heated expression with another treatment device.

RESULTS

The mean MG secretion score, tear break-up time, corneal staining score, number of MGs yielding liquid secretion and symptom scores all improved significantly from baseline to 1 week. This was maintained through the 3-month follow-up. There was no statistically significant difference in any outcome between the automated device treatment only and the additional heated manual expression.

CONCLUSION

The combination of heat applied to the palpebral surface, while simultaneously expressing MGs during a single 12-minute treatment, was effective, in this feasibility study, in treating obstructive MG dysfunction and dry eye signs and symptoms for the 3-month study period.

Nonobvious obstructive meibomian gland dysfunction

This review presents the rationale and supporting data for a recent paradigm shift in our understanding of meibomian gland dysfunction (MGD). The historical understanding of MGD has been that of an infectious hypersecretory disorder with obvious signs of inflammation, hypersecretion, and purulent excreta. The current understanding of MGD now includes the polar concept of a less obvious or nonobvious type of hyposecretory obstructive MGD, where inflammation and other signs of pathology may be absent unless special examination techniques are employed. A new term, nonobvious obstructive MGD (NOMGD), is used to describe what may be the most common form of obstructive MGD. Obstructive MGD is an area of growing importance because obstructive MGD is now recognized to be the most common cause of evaporative dry eye, and because NOMGD seems to be the precursor to obvious obstructive MGD, it is also an important area to understand. The prevalence of NOMGD seems to be very high but currently significantly underdiagnosed. This review presents the relevant anatomy and physiology, concepts of obstructive MGD, the usual absence of inflammation in obstructive MGD, nomenclature and classification of obstructive and NOMGD, clinical diagnosis of NOMGD emphasizing the necessity for diagnostic expression, the use of a new instrument for diagnostic expression providing a standardized method of assessing meibomian gland functionality, the complementary roles of the aqueous and lipid layers, and the specific treatment of NOMGD, emphasizing that the success of treatment of all forms of obstructive MGD is dependent on the relief of the obstruction.