Effects of ophthalmic vehicles on the stability of the precorneal film

Topical anti-glaucoma medications effects on meibomian glands: Systematic review and meta-analysis

Meibomian gland (MG) dysfunction and glaucoma are very prevalent ocular conditions that significantly impact patients' quality of life. A growing number of clinical and experimental studies have reported an association between the use of topical eye drops to reduce intraocular pressure and the development or exacerbation of MG dysfunction. Studies investigating the impact of glaucoma eyedrops on MG diagnostic parameters have shown variable results, particularly regarding the morphology and function of MG and tear film instability. Herein, we corroborated the findings of greater changes in morphological and functional variables related to MG in patients treated with antiglaucoma eye drops through a systematic review and meta-analysis.

The role of meibography in ocular surface diagnostics: A review

The meibomian glands are lipid-secreting glands located in the tarsal plates, whose secretory products cover the tear film, thereby reducing evaporation as well as ensuring lubrication of the ocular surface. The meibomian glands can be visualized at different levels of magnification by infrared meibography, laser confocal microscopy, and optical coherence tomography. These imaging modalities have been subject to much research and progress in clinical practice and have shaped our current understanding of meibomian glands in health and disease. In this review, we explore the evolution of meibography over the past decades, the major contributions of various meibographic modalities, and discuss their clinical significance.

In vivo confocal microscopy: qualitative investigation of the conjunctival and corneal surface in open angle glaucomatous patients undergoing the XEN-Gel implant, trabeculectomy or medical therapy

Purpose

Assessing the quality of the ocular surface by in vivo scanning laser confocal microscopy (IVCM) in primary open angle glaucoma (POAG) patients treated by Xen 45 Gel Stent, medical therapy and trabeculectomy.

Methods

Retrospective, single-center, single-masked, comparative study including 60 eyes of 30 patients (mean age 61.16 ± 10 years) affected by POAG. Eyes were divided into 3 groups: Group 1 eyes underwent the Xen 45 Gel Stent procedure, Group 2 eyes were under medical therapy, Group 3 eyes were surgically treated by trabeculectomy. All patients underwent HRT II IVCM analysis of cornea, limbus, conjunctiva, sub-tenionian space and sclera.

Results

The Xen 45 Gel stent, if properly positioned in the sub-conjunctival space preserves goblet cells and limits ocular surface inflammation. Regular corneal epithelial cells with micro-cysts, and normo-reflective sub-epithelial nerve plexus are documented by IVCM. In sub Tenon’s implants an alternative lamellar intra-scleral filtration is detectable. Combined surgical procedures show a noticeable number of inflammatory cells with rare micro-cysts. Post-trabeculectomy inflammatory reaction is more evident than Xen 45 Gel Stent associated surgical procedures, but less than medical therapy where a conspicuous presence of Langerhans cells, peri-neural infiltrates, marked loss of goblet cells and fibrosis is visible.

Conclusion

Ocular surface inflammation was more notable in topical therapy than after trabeculectomy, which itself causes more inflammation than XEN Gel stents.

Tear fluid-eye drops compatibility assessment using surface tension

OBJECTIVE

To evaluate the compatibility of commercially available eye drop surface tension with the tear film physiological range and to characterize commonly used ophthalmic excipients in terms of their surface activity under eye-biorelevant conditions.

SIGNIFICANCE

There are a number of quality requirements for the eye drops (e.g. tonicity, pH, viscosity, refractive index) that needs to comply with the physiological parameters of the eye surface. However, the adjustment of surface tension properties of the eye drops to the normal range of surface tension at the air/tear fluid interface (40-46 mN/m) has received rather less attention thus far. Yet, the surface tension at the air/tear fluid interface is of vital importance for the normal function of the eye surface.

METHODS

The surface tension compatibility of the isotonic aqueous solutions of commonly used ophthalmic excipients as well as 18 approved eye drops with the tear fluid have been evaluated using surface tension method.

RESULTS

Each ophthalmic ingredient including the preservatives, solubilizing agents and thickening agents can influence the surface tension of the final formulation. In case of complex ophthalmic formulations one should also consider the possible interactions among excipients and consequent impact on overall surface activity. Out of 18 evaluated eye drops, three samples were within, 12 samples were below and three samples were above the physiological range of the tear fluid surface tension.

CONCLUSIONS

Our results provide a rationale for clinical studies aiming to assess the correlation between the eye drops surface tension and the tear film (in)stability.

Effect of preserved and preservative-free timolol eye drops on tear film stability in healthy Africans

Background:

Preserved versus nonpreserved formulations for ophthalmic use have been well described in the literature although not specifically in the African population where beta blockers are frequently used as the first-line therapy due to economic and availability issues. This study sought to determine the effect of preserved and preservative-free Timolol eye drops on tear film stability in healthy black Africans.

Materials and Methods:

Sixty healthy nondry eye subjects aged 19–25 years were randomly assigned into four groups (n = 15) and differently treated with eye drops of phosphate buffered saline (PBS), preservative-free timolol (PFT), benzalkonium chloride (BAK) only, and BAK-preserved timolol (BPT). Noninvasive tear break-up time (NITBUT) was measured using the keratometer at baseline and 30, 60, and 90 min after drop application.

Results:

No significant decline in NITBUT was observed following treatment with PFT and PBS. However, BAK treatment showed a positive time-dependent significant decline in NITBUT (P < 0.001) while a significant decline in the BPT-treated group was only found at 90 min (−3.52 s; P < 0.001). In comparison to the PFT-treated group, treatment with BAK and BPT showed significantly lower NITBUT (P < 0.001).

Conclusion:

BPT is associated with a significant decline in tear film stability in black Africans. This finding has implications in the management of glaucoma in patients with high-risk of dry eyes in this population.

Postanaesthetic tear production and ocular irritation in cats

OBJECTIVE

General anaesthesia significantly reduces tear production and normal values are not immediately re-established on ending anaesthesia. Therefore, adequate protection of the cornea has to be assured during the perianaesthetic period. There are various methods available, including taping of the eyelids and the application of eye ointments, gels and drops. In human medicine studies, different formulations were found to induce signs of ocular irritation. The aim of the present study was to determine tear production in cats after general anaesthesia, and to identify possible causes of irritation.

MATERIAL AND METHODS

Tear production was determined in 41 cats after general anaesthesia and eyes were examined for signs of irritation. Two different anaesthetic protocols were used. To protect the cornea, an ointment and gel were applied to the right and left eyes, respectively.

RESULTS

Postoperatively, tear production was significantly reduced for 6 hours and 18 hours in the right and left eyes, respectively. Two hours after anaesthesia, blepharospasm of the right eye was observed in 92.7% (n = 38) of the cats. In contrast, the left eye was always held open.

CONCLUSIONS

This study demonstrated that tear production in cats is significantly decreased both during and after anaesthesia. The degree of reduction was independent of the anaesthetic protocol. Both the eye ointment and gel proved effective in protecting the corneal surface. However, eye gel use is recommended because the eye ointment consistently caused an irritation comparable to the foreign-body sensation reported in humans.

Efficacy and safety of benzalkonium chloride-free fixed-dose combination of latanoprost and timolol in patients with open-angle glaucoma or ocular hypertension

Background

Benzalkonium chloride (BAK) is a common preservative in topical ocular preparations; however, prolonged use may lead to deleterious effects on the ocular surface, affecting quality of life and reducing adherence to treatment and overall outcomes. This study compared the intraocular pressure (IOP)-lowering efficacy and safety of a novel once-daily, BAK-free, fixed-dose combination of latanoprost plus timolol with latanoprost or timolol administered as monotherapy or concomitantly.

Methods

This was a 6-week, randomized, open-label, parallel-group, active-controlled study in patients aged ≥18 years with open-angle glaucoma or ocular hypertension. A total of 227 patients were randomized to either a once-daily, BAK-free, fixed-dose combination of latanoprost 0.005%/timolol 0.5% ophthalmic solution or concomitant administration of once-daily latanoprost 0.005% plus twice-daily timolol 0.5% or once-daily latanoprost 0.005% monotherapy, or twice-daily timolol 0.5% monotherapy. Efficacy end points were assessed at three time points on visits at weeks 1, 2, 4, and 6 versus baseline.

Results

The IOP-lowering efficacy of the fixed-dose combination of latanoprost/timolol was similar to that of latanoprost plus timolol administered concomitantly at all time points (mean IOP difference and 95% confidence interval within ±1.5 mmHg; P=0.4223 to P=0.9981). The fixed-dose combination of latanoprost/timolol demonstrated significantly better IOP-lowering efficacy than timolol monotherapy at all time points (P=0.001 to P<0.0001) and significantly better IOP-lowering efficacy than latanoprost monotherapy at all time points. Responder rates on at least one time point and on at least two time points with fixed-dose combination latanoprost/timolol were similar to those with concomitant latanoprost plus timolol (85.5% versus 82.1%, P=0.6360; 78.2% versus 75%, P=0.6923), but significantly better than either latanoprost or timolol monotherapy (68.5%, P=0.0355; 55.4%, P=0.0005; 57.4%, P=0.0202; and 46.4%, P=0.0006, respectively). No significant differences in ocular and nonocular treatment-emergent adverse events were found between the treatment groups.

Conclusion

A BAK-free, fixed-dose combination of latanoprost 0.005%/timolol 0.5% was as effective and well tolerated as concomitant latanoprost and timolol for treatment of elevated IOP in patients with open-angle glaucoma or ocular hypertension.

Comparison of the long-term effects of various topical antiglaucoma medications on meibomian glands

PURPOSE

To examine the effects of long-term antiglaucoma eye drop treatment on meibomian glands.

METHODS

The subjects were 71 eyes of 71 glaucoma patients (group 1) receiving one type of antiglaucoma eye drops, 61 eyes of 61 glaucoma patients (group 2) receiving two types of antiglaucoma eye drops, and 30 eyes of 30 glaucoma patients (group 3) receiving three types of antiglaucoma eye drops. Controls comprised 75 eyes of 75 healthy volunteers. Subjective symptoms were evaluated by questionnaire, and lid margin and superficial punctate keratopathy were evaluated by slit lamp examination. Meibomian glands of upper and lower eyelids were observed and scored using noncontact meibography (meiboscore). Tear film break-up time (BUT) was measured and meibum was graded.

RESULTS

Lid margin abnormality, superficial punctate keratopathy, meiboscore, and meibum scores were significantly higher in glaucoma patients than in controls (P < 0.001). BUT and Schirmer scores were significantly lower in glaucoma patients than in controls (P < 0.001). Subgroup analysis of the parameters in group 1 revealed no significant difference between patients receiving prostaglandin and those receiving β-blockers, or among groups 1, 2, and 3. Multivariate regression analysis demonstrated that meiboscore significantly correlated with lid margin abnormality score (P = 0.007) and BUT (P = 0.045) in group 1; with BUT (P = 0.004), symptom score (P = 0.003), and age (P = 0.026) in group 2; and with lid margin abnormality score (P = 0.001) in group 3.

CONCLUSIONS

Long-term use of antiglaucoma eye drops was associated with alterations in meibomian gland morphology and function.

Corneal protection during general anesthesia for nonocular surgery

Corneal abrasion is the most common ophthalmologic complication that occurs during general anesthesia for nonocular surgery. Such abrasions can be caused by a variety of mechanisms and can lead to sight-threatening microbial keratitis and permanent scarring. There is no standard mode of protecting the cornea during general anesthesia for nonocular surgery. Methods described in the literature are not entirely effective and may be associated with unwanted side effects. Taping alone provides protection that is equivalent or superior to other interventions and has fewer side effects. Petroleum gel is flammable and is best avoided when electrocautery and open oxygen are to be used around the face. Preservative-free eye ointment is preferred, as preservative can cause corneal epithelial sloughing and conjunctival hyperemia. Recently, the application of Geliperm and bio-occlusive dressings has been advocated. Geliperm may be particularly useful during endonasal surgery when continuous perioperative observation of the eye is required. In this article, the literature on the etiology of perioperative corneal abrasions is reviewed and various protection strategies are compared in order to identify the best methods to prevent corneal abrasions during general anesthesia.

Time course of changes in ocular wavefront aberration after administration of eye ointment

PURPOSE

To investigate the influence of an eye ointment on ocular aberration.

DESIGN

Prospective, comparative study.

METHODS

In 10 normal volunteers, ocular aberration was assessed before and 5, 30 min, 1, 2, 3, 6, and 12 h after administration of ofloxacin eye ointment. Ocular aberration was sequentially measured over a period of 10 s, and the root mean square (RMS) of the second-, third-, fourth-, and total higher-order aberrations (HOAs) were determined. From the sequential changes in total HOAs during 10 s, the fluctuation index (FI) and stability index (SI) were calculated. The obtained data were compared with those of another 17 normal volunteers who received timolol maleate gel-forming ophthalmic solution.

RESULTS

No significant changes in second-order RMS were observed after administration of the ointment. HOAs such as third-, fourth-, and total higher-order RMS significantly changed during the study period (P<0.05, repeated-measures analysis of variance). The RMS of each HOA component significantly increased 5 min after administration compared with the baseline values (P<0.05, Dunnett test). FI also increased significantly 5 min after administration (P<0.05), but SI did not change significantly. When compared with the results of the gel-forming solution group, HOAs and FI showed significantly higher values at several time points during 6 h after application (P<0.05, Mann-Whitney U-test).

CONCLUSIONS

Administration of eye ointment significantly degrades optical quality of the eye by increasing and oscillating HOAs. These changes were more pronounced than those after instillation of gel-forming ophthalmic solution for at least several hours.

Effects of long-term topical anti-glaucoma medications on meibomian glands

OBJECTIVE

To examine effects of long-term topical anti-glaucoma medications on meibomian gland morphology and function and assess their relationship with slit-lamp findings.

METHODS

This was a cross-sectional observational case series of 31 patients with glaucoma (mean age ± standard deviation, 65.0 ± 13.0 years; mean duration of eye drop use, 7.9 ± 6.0 years) treated with topical anti-glaucoma drugs in only one eye for more than 1 year: 13 receiving prostaglandin analogues (PGs) alone, eight receiving β-blockers alone, and ten receiving multiple treatments. Untreated contralateral eyes served as controls. Lid margin (lid margin abnormality score: 0-4) and superficial punctate keratopathy (SPK score: 0-1) were observed with a slit lamp. Upper and lower eyelids were turned over to observe meibomian glands using non-contact meibography. Meibomian gland loss was scored for each eyelid from grade 0 (no loss of meibomian glands) through grade 3 (loss >2/3 of total meibomian gland area). Meibomian lipid content (meibum) was scored (meibum score: 0-3).

RESULTS

Treated eyes had significantly higher scores for lid margin abnormality (P= 0.001), SPK (P< 0.001), meibo-score (P< 0.001), and meibum (P< 0.001) than control eyes. Tear film break-up time (BUT) was significantly shorter in treated eyes than in control eyes (P= 0.001). Schirmer values were significantly lower in treated eyes than in control eyes (P= 0.0039). Subgroup analysis indicated a significantly higher meibo-score in eyes treated with PGs (P= 0.0046) and in eyes treated with β-blockers (P= 0.0231) than in the corresponding controls.

CONCLUSIONS

Long-term anti-glaucoma eye drop use affects meibomian gland morphology and function.

Effect of water-in-oil microemulsions and lamellar liquid crystalline systems on the precorneal tear film of albino New Zealand rabbits

The aim of this study is to investigate the effect of phase transition water-in-oil (w/o) microemulsions (ME) and liquid crystalline systems (LC) on the precorneal tear film (PCTF). The study used six albino NZ rabbits and monitored the integrity and stability of the PCTF before and after instillation of test formulations. The effects were evaluated by assessment of the PCTF lipid layer using interferometry, tear evaporation rate measurements, and indirect estimation of tear volume. Ocular application of test formulations changed the appearance of the PCTF lipid layer, indicating lipid layer disruption. The recovery time was longer in case of ME compared with an aqueous solution (SOL). The tear evaporation rate was increased after application of both ME and LC systems compared with the SOL, with the LC system showing the greatest effect. Tear volume measurement results revealed minimal changes associated with the instillation of both ME systems. Whilst phase transition w/o ME systems can interact with the PCTF lipid layer in albino New Zealand rabbits, their effect on the volume of resident tears was found to be minimal.

[Ocular toxicity of benzalkonium]

In order to meet the requirements of the pharmacopeia, ophthalmic preparations have to be manufactured in conditions that can secure their sterility before use and can prevent the development of micro-organisms after opening of the vial. The addition of an appropriate preservative is a way to meet this requirement. However, in addition to their lack of efficacy in certain conditions, they can be problematic in terms of formulation, stability and interaction with the packagings. Furthermore, their daily and repeated use in chronic pathologies such as glaucoma, dry eye or allergy has revealed their nuisance. Moreover, the recognition of certain parameters such as life quality and therapeutic observance has strengthened the proofs that have already been clinically shown. The review of the experimental and clinical data already published about the toxicity of the preservatives shows that almost every ocular structure is affected to various extents. From the first assumption data to preclinical and clinical proofs, this article highlights the evolution of the understanding process towards the toxic role of preservatives.

Effects of prostaglandin analog therapy on the ocular surface of glaucoma patients

Purpose:

To quantify changes in tear break-up time (TBUT), corneal staining and ocular surface disease index (OSDI) in glaucoma patients after switching therapy from latanoprost with 0.02% benzalkonium chloride (BAK) to travoprost with sofZia^™.

Methods:

Prospective consecutive case series evaluating patients before and 8 weeks after switching from latanoprost with BAK to travoprost with sofZia^™ in patients with baseline TBUT less than 6 seconds.

Results:

Forty eyes of 20 consecutive patients using latanoprost with BAK were switched to travoprost with sofZia^™. Mean TBUT prior to starting travoprost was 2.02 ± 0.71 seconds and increased to 6.34 ± 1.31 seconds 8 weeks after the switch (p < 0.001). Mean inferior corneal staining scores decreased from 2.40 ± 0.87 to 1.38 ± 0.59 (p < 0.001). Mean OSDI scores decreased from 26.31 ± 8.25 to 16.56 ± 6.19 (p < 0.001).

Discussion:

This report focuses on the status of the ocular surface, as documented by TBUT, corneal staining and OSDI, in patients switched from latanoprost with BAK to travoprost without BAK. The switch resulted in a statistically significant increase in TBUT and decreases in corneal staining and OSDI in patients with low baseline TBUT values.

Conclusion:

BAK, a common preservative for glaucoma drops, may increase OSD by disrupting the tear film and increasing conjunctival inflammation. In this study, a change from a BAK-preserved prostaglandin analog (PGA) to a non-BAK-preserved PGA resulted in a measurable improvement of TBUT, corneal staining and OSDI. Further studies are needed to better understand the impact of BAK-preserved medications on the ocular surface.

German register for glaucoma patients with dry eye. I. Basic outcome with respect to dry eye

BACKGROUND

The purpose of this register was to determine the links between glaucoma, age, concomitant disease, medication, and dry eye in a large group of glaucoma patients.

METHODS

A total of 20,506 patients from 900 centers across Germany were included. The first 30 consecutive glaucoma patients at each center were recruited. Epidemiological data as well as information on glaucoma, medication, concomitant diseases, dry eye, and local symptoms were elicited by means of a questionnaire. We analyzed primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PEX), and pigmentary glaucoma (PDG).

RESULTS

According to the register data, more women develop dry eye and glaucoma than men (56.9 vs. 45.7%). The most frequent concomitant systemic diseases were hypertension (48.1%), diabetes mellitus (22.5%), and dry mouth, nose, and skin (11.3%). As expected, the highest incidence of dry eye was found in those patients with dry mouth, nose, and skin. Dry eye occurred with dissimilar frequencies in association with the various glaucoma types: PEX>POAG>PDG. The incidence of dry eye increases with age. The gender difference in the occurrence of dry eye becomes apparent from the age of 50. Dry eye occurred more frequently when three or more antiglaucoma drugs were used and increased with the duration of glaucoma disease.

CONCLUSIONS

We publish the first results from the German Glaucoma and Dry Eye Register. We found that the occurrence of dry eye is linked to several factors. Thus, the type of glaucoma has an impact on the risk of dry eye. The quantity of eye drops applied also plays a role in the development of the dry eye syndrome if more than three medications are used. While POAG is usually treated with one drug, PEX and PDG tend to be treated with multiple drugs. The gender difference in the occurrence of dry eye becomes apparent from the age 50 years. Because of the vicious circle of dry eye, antiglaucoma eye drops containing benzalkonium chloride compromises patient compliance. The results of the register are therefore of key relevance for the care of glaucoma patients.

Xerophthalmia secondary to alcohol-induced malnutrition

BACKGROUND

Xerophthalmia refers to the ocular manifestations associated with vitamin A deficiency. Vitamin A deficiency can be caused by numerous disorders, including alcohol-induced malnutrition. The ocular manifestations of xerophthalmia include conjunctival and corneal xerosis (drying), keratomalacia (corneal necrosis/ulceration), nyctalopia (night blindness), and Bitot's spots (conjunctival lesions).

CASE REPORT

A 47-year-old white male with complaints of dryness and difficulty seeing at night presented to our clinic for consultation from general medicine to rule out xerophthalmia. Laboratory testing and general medicine, psychiatry, and nutrition evaluations confirmed the systemic diagnosis of alcohol-induced malnutrition. He admits that his alcoholism was induced by depression. Confirmed associated disorders compounding the malnutrition include alcoholic cirrhosis, protein deficiency, and megaloblastic anemia. The patient had xerophthalmia diagnosed in the optometry clinic as a result of symptoms, slit lamp examination signs, and the associated disorders. The associated disorders were treated with systemic medications and vitamins. Ophthalmic treatment consisted of carboxymethylcellulose-based artificial tears.

CONCLUSIONS

Although xerophthalmia and vitamin A deficiency are more common in underdeveloped countries, their presentation in the United States may be induced by conditions such as liver cirrhosis, malnutrition, and alcoholism. This report summarizes ocular manifestations of alcoholism and presents a case of xerophthalmia secondary to alcohol-induced malnutrition and the role of optometry in its treatment and management.

Disruption of the tear film by the application of small drops of saline and surfactant

The effects of disrupting the tear film by placing 5 or 10 microl drops of saline and mild surfactant solution (SS) directly onto the tear films of 10 subjects were observed and are described here. Disruption of the tear film was only transient, with restoration of the film occurring within about two to three blinks for saline drops, and four to six blinks for SS drops. When a drop of SS was placed on a cornea, two types of black spots/areas may be observed: black areas apparently similar to those observed in the TBUT test, and black areas forming outside the border of the pattern of the spreading SS drop. In general, staining of the black areas formed in the fluorescein-stained tears did not occur even when blinking was inhibited for up to 13 s. Stained areas on the corneal surface did not have a tendency to form black spots first; the tear film over these areas did not appear to be less stable than on other areas of the corneal surface.

Ocular tolerance of preservatives and alternatives

Eye drops are multiple dosage forms protected against microbial contamination by means of preservatives. However, the ocular tolerance of these chemicals can vary and this may result in adverse toxic or allergic reactions. This overview presents the pharmacopoeial requirements for the preservation of eye drops, the factors affecting ocular tolerance as well as the adverse external ocular effects induced by preservatives. The alternatives to the use of preservatives are also discussed, including the recent progress in eye drops packaging.

Prevalence of ocular symptoms and signs with preserved and preservative free glaucoma medication

AIM

To determine the incidence of ocular toxicity of preservatives with glaucoma medications.

METHODS

A prospective epidemiological survey was carried out in 1999 by 249 ophthalmologists on 4107 patients. Ocular symptoms, conjunctiva, cornea, and eyelids were assessed. A chi(2) test was used for differences between preserved eye drops (P) and preservative free eye drops (PF).

RESULTS

84% patients used P, 13% received PF, and 3% a combination of P and PF eye drops. All symptoms were more prevalent with P than with PF drops (p<0.001): discomfort upon instillation (43% versus 17%), and symptoms between instillations such as burning-stinging (40% versus 22%), foreign body sensation (31% versus 14%), dry eye sensation (23% versus 14%), tearing (21% versus 14%), and eyelid itching (18% versus 10%). An increased incidence (>2 times) of ocular signs was seen with P eye drops. The prevalence of signs and symptoms was dose dependent, increasing with the number of P drops. A reduction in the symptoms and signs was observed when patients changed from P to PF eye drops (p<0.001).

CONCLUSIONS

Symptoms and signs are less prevalent when PF drops are used. Moreover, most of the adverse reactions induced by P glaucoma medication are reversible after removing preservatives.

Corneal toxicity secondary to inadvertent use of benzalkonium chloride preserved viscoelastic material in cataract surgery

AIMS

To study the long term toxic effects of intraocular benzalkonium chloride (BAC).

METHODS

19 patients exposed to intraocular BAC preserved viscoelastic during cataract surgery in February 1999 developed severe striate keratopathy immediately postoperatively. 16 patients, including two who underwent penetrating keratoplasty, were studied in the period April to June 2000. Ocular symptoms, visual acuity, biomicroscopy, intraocular pressure, dilated funduscopy, specular endothelial microscopy, and corneal pachymetry findings were recorded. The corneal and iris specimens of the two patients who underwent keratoplasty were studied by light, transmission, and scanning electron microscopy.

RESULTS

Six males and 10 females, aged 64-98 years, were studied 14-16 months postoperatively. All patients were symptomatic. 12 patients had best corrected visual acuity of 6/12 or better and four patients of between 6/18 and 6/60. Five patients had corneal epithelial oedema and 11 had Descemet's membrane folds. The central corneal thickness, 620 (SD 71) microm, in affected eyes was significantly higher (p<0.005, two tailed paired t test) than that of the contralateral eyes, 563 (SD 48) microm. The endothelial cell density was significantly lower (p<0.0001, two tailed paired t test) in affected eyes: 830 (SD 280) cells/mm2 v 2017 (SD 446) cells/mm2. The mean average cell area was significantly higher in the BAC treated eyes: 1317 (SD 385) microm2 v 521 (SD 132) microm2. There was no significant difference in the coefficient of variation of cell size between the two eyes (p=0.3, two tailed paired t test). Two corneal specimens displayed morphological features of bullous keratopathy and other non-specific abnormalities. Extracellular melanosomes were present in a portion of the iris of one case.

CONCLUSION

BAC is toxic to the corneal endothelium when used intraocularly, leading to severe striate keratopathy. This cleared in most cases but left varying degrees of residual stromal thickening in all eyes. If penetrating keratoplasty is required the results are excellent.

How the most common preservative affects the Meibomian lipid layer

PURPOSE Effects of preservatives like benzalkonium chloride on the tear film are often hypothetized. With regard to the Meibomian lipid layer only few data are available. In order to receive precise information about the effect of benzalkonium chloride on the Meibomian lipid layer we performed in vitro experiments using a direct optical control of the films. METHODS Meibomian gland secretion was spread on a water subphase containing benzalkonium chloride in concentrations of 0.001%, 0.005%, 0.01%, 0.05%, and 0.1%, respectively. This aqueous subphase was chosen in analogy to the aqueous tear film layer. In our experimental assay, the pH was 5.5, the temperature was 20 degrees C. The spreading process and the quality of the films were controlled by the Brewster Angle Microscope. RESULTS Benzalkonium chloride was well tolerated up to concentrations of 0.005%. Concentrations > 0.005% affected the spreading process forming domains, and instable films. CONCLUSIONS. Thus it could be demonstrated that there is a critical concentration of benzalkonium chloride which destroys the spreading and alters the morphology of the Meibomian lipid layer. These results were confirmed by a modified method injecting benzalkonium chloride in the subphase after spreading the Meibomian lipid layer. Therefore eye drops with benzalkonium chloride in concentrations above 0.005% should be abandoned in clinical therapy.

Ocular tolerance of preservatives on the murine cornea

We investigated the effects of instilling 13 commonly used preservatives on the murine cornea in vivo. Due to the instillation of preservatives, micro-lesions are formed on the cornea and can be selectively marked by fluorescein. The sum of the resulting fluorescent areas was measured using an episcopic microscope coupled to an image processing system. All the tested preservatives proved to be well-tolerated by the eye at commonly used concentrations. However, in some cases, increased concentrations of preservatives or combinations resulted in significant increase of the amount of corneal damage. With increasing the concentration, corneal lesion increased the most in the case of cetylpyridinium. While a combination of chlorobutanol 0.5% and phenylethylalcohol 0.5% did not result in an increase in corneal damage (when compared to the use of each separately), the associations of thiomersal 0.02% and phenylethylalcohol 0.4% on one hand and of edetate disodium (EDTA) 0.1% and benzalkonium 0.01% on the other, resulted in significant increases in the amount of corneal damage. However, in none of the tested combinations, the increase in the observed damage exceed the limit of ocular intolerance we had defined beforehand: thus, they were all deemed relatively well-tolerated. In the last part of the study, we investigated the effects of combining several preservatives, at usual concentrations, with an anesthetic solution of oxybuprocaine and found no notable increase in ocular damage.

Effects of morphine on corneal sensitivity and epithelial wound healing: implications for topical ophthalmic analgesia

Studies were conducted to examine the analgesic and toxic effects of topical morphine on corneal abrasion. For the toxicity study, rabbits were anaesthetized and epithelial cells were removed from the cornea and limbus. Animals were randomised and treated topically as follows: (1) saline (control); (2) morphine sulphate (MS, 0.5%); and (3) proxymetacaine hydrochloride (proparacaine) (PH, 0.5%). Two drops of the solution were instilled in the eyes at 4 hour intervals for 6 consecutive days and the progression of corneal wound healing was assessed. Results showed that repeated topical MS had no adverse effects on corneal wound closure. The rates of wound healing were similar in both saline and MS treated groups. Eyes treated with MS showed wound closure in a symmetrical fashion starting on day 2 following abrasion. The progression of epithelial wound healing was completed by day 4 in one eye, by day 5 in three eyes, and by day 7 in five eyes. In contrast, repeated topical PH application delayed corneal wound closure. Eyes treated with PH showed signs of corneal wound closure on the third day, but only two eyes out of six had completed wound closure by the eighth day after corneal abrasion. In a subsequent masked study, the analgesic efficacy of topical MS was assessed in seven patients with unilateral corneal abrasion. In all cases, a baseline response was first established. Subsequently, saline was instilled in both eyes and the patient's corneal response to pain pressure was determined 10 and 20 minutes later. Finally, MS was applied and the analgesic effect on the cornea was assessed. Results showed that saline had no effect compared with the baseline response. In contrast, MS showed an analgesic effect as early as 10 minutes after application in the eye with corneal abrasion. MS showed an analgesic efficacy of 4.3-fold and 5.5-fold greater than the baseline or saline on the eye with corneal abrasion. However, MS had no analgesic effect on the intact corneal. Collectively, these data indicate that opioids do have a desirable analgesic property with out irritating or causing any adverse effect on ocular structures.

Mechanical manipulation of the lids and tear break-up time measurements in Hong Kong Chinese

We measured tear break-up time (TBUT) after lid-rubbing in a single masked experiment, and found that TBUT was unaltered. A further single masked experiment in which non-invasive tear break-up time (NITBUT) was measured after the lids were raised as if to apply fluorescein also showed no effect of this interference with the lids. An experiment in which fluorescein was applied either with the lid raised or not raised during fluorescein application, again with the experimenter masked with respect to treatment, also produced no significant difference in TBUT. When we measured TBUT with the lid raised so that it was not in contact with the cornea, there was no difference in TBUT for the group between the 'lifted' and 'non-lifted' eye; some subjects showed substantially shorter TBUT values, while others showed substantially longer TBUT values. These findings are surprising in view of the concerns expressed in the literature regarding the sensitivity of the tear film to mechanical interference, and suggest that the tear film is more resistant to disruption than has previously been thought.

Foam at inner eye canthus in office workers, compared with an average Danish population as control group

Foam formation in the eye canthus is well-known. The presence of foam was observed in 169 office workers in 4 town halls in Copenhagen County compared with 112 control persons from the general population in the same area. The presence of foam depends on age and gender. A significant increase with age was observed in the control population (P = 0.0078). In both groups, females had a significantly lower occurrence of foam than males (P = 0.0043, P = 0.010). This difference was mainly caused by the use of eye make-up. After correction for age, gender and use of eye make-up, the prevalence of foam was significantly lower in the office population than in the control population (P less than 0.0001). Furthermore, low foam formation was significantly correlated to reported subjective eye irritation in the office population (P = 0.0074), but not in the control population (P = 0.40). Also, significant positive correlation between absence of foam and different degrees of dry eyes (expressed as a combination of premature break-up of the precorneal tearfilm and lissamine green stained epithelial damage of the bulbar conjunctiva) was found both in the office population and in the control population (P = 0.0090, P = 0.0034). However, after correction for the more frequent appearance of dry eyes in the office population, foam was still observed significantly less frequently in the office population than in the control population (P = 0.0001). It is concluded that the decreased foam formation in the office worker constitutes a key symptom in the development of 'office eye syndrome'. In what way the office environment influences the foam formation is unknown. Possible mechanisms are discussed.

Clinical trial of sustained-release artificial tears in keratoconjunctivitis sicca and Sjögren's syndrome

The effect of sustained-release artificial tear inserts on symptoms and signs of reduced tear production in keratoconjunctivitis sicca (KCS) was evaluated in an open clinical trial including 30 patients. A significant relief of sicca symptoms and a decrease in keratoconjunctival staining were seen in 10 patients fulfilling the study, whereas no significant effect on Schirmer test and tear break-up-time could be detected, neither in patients with pure KCS nor with KCS as a manifestation of Sjögren's syndrome. Twenty patients (67%) withdrew due to adverse effects, which were reported in total 80% of the patients. Absence of measurable tear secretion predicted treatment failure. Due to the frequent side effects, the artificial tear inserts cannot be recommended as a first line treatment in KCS patients.

Tear film flow and stability in acute and chronic conjunctivitis

Tear film flow and stability studies were carried out in patients suffering from acute and chronic conjunctivitis by performing Schirmer test-I and break-up-time (BUT) measurements. In this clinical study, patients with chronic conjunctival inflammation demonstrated a premature break-up of tear film despite normal amounts of aqueous tears. In acute catarrhal conjunctivitis the values of BUT were within normal limits, whereas the values of Schirmer test-I were significantly higher (t-test, P less than 0.001) and are considered to be due to reflex hypersecretion of tears.

Study of tear film flow and stability in chronic dacryocystitis

Tear film flow and stability studies were carried out in patients suffering from chronic dacryocystitis by performing Schirmer test-I and tear film break-up-time (BUT) measurements. The results of Schirmer's test corroborated the theory that a reduced out flow of tears causes a compensatory reduced tear secretion. The results of break-up-time confirm the fact that BUT is independent of outflow of tears in patients with epiphora.

Topical anaesthetic and tear film stability

The effect of unpreserved topical anaesthetic on tear film stability (0.4% oxybuprocaine hydrochloride) was investigated in a double masked randomised study in 12 healthy volunteers, using a noninvasive tear film break up technique (NIBUT). It was found that the topical anaesthetic did not reduce the pre-corneal tear film stability, contrary to the electron microscopic evidence.

A comparative clinical study of tear substitutes in normal subjects and in patients with keratoconjunctivitis sicca

The effect upon the tear film of a new tear substitute, Dacriosol, was compared to a non-viscous solution, saline, an to a highly viscous solution, Isopto Plain, in 15 normal healthy subjects and in 15 patients with mild to moderate keratoconjunctivitis sicca. No differences between the test solutions could be measured 3 h after last medication regarding: Schirmer's test, break-up time, rose bengal staining, corneal sensitivity and tear content of lysozyme. The test persons could not discriminate subjectively between the effect of the test solutions. The investigation parameters show an equal effect of Dacriosol, Isopto Plain and saline both in normal healthy subjects and in patients with keratoconjunctivitis sicca.

Peroperative protection of cornea and conjunctiva

In 221 consecutive cataract extractions the peroperative epithelial damage was assessed by vital staining with 1% lissamine green, using logarithmic grading (grade 5 more than 10 000 stained dots) on cornea and on the superior, medial, lateral, and inferior conjunctiva. Evenly spread dots were seen on the cornea in 63 per cent of the eyes not subjected to protective treatment. In 35 per cent we observed staining caused by taut suturing of cornea and/or conjunctiva, in 10 per cent horizontal lines due to corneal bending during the extraction. The cornea was protected most effectively by healon (1% instilled once). Saline (4 or 5 instillations during the operation sufficed) protected equally well as gelatin sponge, methylcellulose, polyvinyl alcohol, and a soft contact lens. The inferior conjunctiva was protected only by healon, the superior also by saline, gelatin sponge, and polyvinyl alcohol.

Protection of the eyes with ophthalmic ointments during general anaesthesia

In a double blind trial 47 anaesthetized patients were given eye protection with the paraffin-based neutral eye ointment Ph. Nord. 63 in one eye and the water-based Methyl cellulose (MC) 4% in the other. Twenty-four hours later the eyes were vital-stained with rose bengal/fluorescein. No unintended effects of the ointments were found and no injury to the eyes were seen. Compared with the paraffin-based ointment the MC ointment produced a more firm adhesion of the eyelids. A water-based 4% MC ointment is therefore as alternative to the fat-based neutral eye ointment.

Corneal cytotoxicity of topically applied drugs, vehicles and preservatives

The toxicity and side effects of drugs and their adjuncts are reviewed according to effect on corneal epithelium, stroma, and endothelium, when topically applied to healthy or wounded surfaces, or introduced into the anterior chamber of the eye. Corneal research techniques are reviewed, including scanning and transmission electron microscopy, electrophysiological techniques, and specular microscope observation. Clinical interpretation of these results is discussed. Reviews of specific toxicologic techniques and of medications are cited. Present research makes it increasingly apparent that not only medications but also their preservatives cannot be considered innocuous. Preservatives may be effective yet less damaging to the ocular integument when used at lower concentrations than those presently available commercially. Complete avoidance of preservatives by the use of special dispensing systems is found increasingly desirable.