Agreement Analysis on Angle Characteristics With Automated Gonioscopy

PRCIS

Automated gonioscopy is a recent method of recording angle pictures. Our study shows that agreement between observers is moderate in most categories used in clinical practice, underlying its clinical usefulness but also room for improvement.

INTRODUCTION

Iridocorneal angle (ICA) imaging methods have been recently developed to record gonioscopic images. The purpose of this study was to perform an interrater agreement analysis of ICA photographs.

METHODS

Multicentric cross-sectional observational study. Consecutive patients in 2 ophthalmology departments underwent automated gonioscopy. One picture per quadrant from each eye was selected for randomization. Pictures were graded and analyzed by 4 masked glaucoma specialists regarding angle opening, width, Shaffer and Spaeth gradings and other findings. Fleiss' κ statistics was performed to assess interrater agreement.

RESULTS

A total of 50 patients were recruited, with the sample containing a variety of diagnosis including pseudoexfoliation (22%), angle-closure suspect (12%), and pigmentary glaucoma (4%). The sample included phakic (68%) and pseudophakic patients, as well as cases with gonio-implanted surgical devices (10%). There was moderate agreement on angle opening, angle width, presence of angle vessels, and peripheral anterior synechiae (κ=0.435, 0.511, 0.558, 0.488, respectively; P<0.01). Fair agreement was observed regarding Shaffer grading, site of iris root insertion, angle pigmentation features, and the presence of iris processes. Expectedly from a 2-dimensional picture, the configuration of peripheral iris was found to have a poor agreement. Subset analysis on higher quality pictures seemed to improve agreement on pigment but did not further improve on the overall good agreement on angle opening status.

CONCLUSIONS

Our study shows that automated gonioscopy provides moderate agreement on most clinically relevant features. Binary characteristics such as angle opening or PAS seem to be more robust than more complex angle classification parameters.

The influence of electromagnetic radiation on the measurement behaviour of the triggerfish® contact lens sensor

BACKGROUND

To assess a possible signal drift, noise and influences of electromagnetic radiation on the measurement behaviour of the Triggerfish® contact lens sensor, which might be mistaken as IOP fluctuations.

METHODS

Contact lens sensors (Triggerfish®, SENSIMED AG, Lausanne, Switzerland) were fixed in a water bath. To reduce any external electromagnetic impulses, all plugs were removed from the sockets, no lights were switched on and no electronic devices, except a temperature logger were left in the test room. For 24 h signal drift, noise and the influences of a cordless telephone (Ascom d43 DECT Handset, EU DECT 1880-1900 MHz, Ascom Wireless, Baar, Switzerland), a smartphone (Sony Xperia Go ST27i, Sony Corporation, Tokyo, Japan) and a computer (Hewlett-Packard ProBook 650 15,6″ - D9S33AV, Hewlett-Packard Inc., Palo Alto, USA) on the measuring profile were analysed.

RESULTS

Twenty-four-hour measurements without provoked external electromagnetic impulses yielded a profile without any signal drift and 8.2 mV eq noise. During the activation of the cordless telephone a maximum measurement variation of 3.2 mV eq. (4.1-7.3), smartphone 1.8 mV eq. (4.7-6.5) and computer 1.4 mV eq. (6.3-7.7) were observed.

CONCLUSIONS

During 24-h measurements there was no signal drift and a very low noise. Patients concerned about electronic devices possibly interfering with the measurements of the contact lens sensor, can be informed, that the use of their cordless telephone, smartphone or computer does not cause any problems. The amount of the signal noise might help to define actual IOP fluctuations. Temperature fluctuations might influence the measuring profile.

Operieren wir die Glaukome zu spät?

Aus der Sicht des operativen Glaukomatologen fragt man sich, warum die Patienten erst sehr spät zur Operation zugewiesen werden. Meist besteht schon zur Zeit der Zuweisung zur filtrierenden Operation nach vielen Jahren der konventionellen Therapie ein sowohl funktionell als auch morphologisch fortgeschrittener Glaukomschaden, zusätzlich ist auch oft noch der Augeninnendruck unter einer lokalen Maximaltherapie dekompensiert. Zusätzlich kommt hinzu, dass die Patienten oft ein fortgeschrittenes Alter aufweisen und schon viele Jahre lang mit verschiedenen Kombinationen aus Tropfen therapiert wurden. Sehr spät gestellte Diagnosen stellen eher die Ausnahme dar. Die Gründe für diese späte Zuweisung sind vielfältig. Neben der immer besseren (besser verträglichen und wirksamen) medikamentösen Glaukomtherapie spielen die Abneigung der Patienten gegen den operativen Eingriff (da keine Verbesserung des Sehvermögens zu erwarten ist) und die bis jetzt (noch) nicht verfügbare optimale Glaukomoperation eine entscheidende Rolle. Anhand einer kleinen retrospektiven Studie der letzten 274 zur filtrierenden Glaukomoperation zugewiesenen Patienten sollen die Kriterien für eine rechtzeitige Indikationsstellung erarbeitet und kritisch analysiert werden. In dieser Studie zeigt sich, dass rund ¾ aller Glaukompatienten spät oder zu spät zur Glaukomoperation zugewiesen werden. Für den niedergelassenen Ophthalmologen ohne Spezialisierung im Glaukombereich werden Kriterien formuliert, wann ein Patient zur Glaukomoperation zugewiesen werden sollte. Diese Kriterien sind grundsätzlich für alle Glaukomoperationen anzuwenden. Die Vor- und Nachteile einer filtrierenden Glaukomoperation werden jedoch besonders hervorgehoben, da dieser Eingriff nach wie vor den Goldstandard darstellt. Da aber die Trabekulektomie leider kein optimaler Glaukomeingriff ist, bestehen berechtigte Hoffnungen, dass die moderneren, weniger invasiven und damit auch weniger risikobehafteten Glaukomeingriffe (MIGS) die Indikationen für einen drucksenkenden Eingriff erweitern und damit die Hemmschwelle für die Zuweisung zur Glaukomoperation herabsetzen.

[Current Status of Electronic "Continuous" Eye Pressure Measurements]

Intraocular pressure (IOP) is generally measured at individual points and usually only once, but rarely more often, during office hours and with various different instruments. This is probably inadequate for diagnosis, assessment of progression, and therapeutic decision making, since the IOP is not a static measurement, but rather one that is subject to greater or lesser fluctuations over shorter or longer periods. This has prompted the desire for more regular or even continuous measurements. This can be achieved with self-tonometers (not discussed in this article) or by using electronic aids with sensors in the eye (invasive; in the intraocular lens, in the ciliary sulcus, on the iris, in the posterior or anterior chamber, suprachoroidal or subconjunctival) or on the eye (non-invasive; sensor contact lens). Despite numerous advances and miniaturisations, there is as yet still no continuous measurement technique (either invasive or non-invasive) that can be used routinely, but development of such a device is at an advanced stage.

Measurement of tumor necrosis factor-alpha, interleukin-6, Fas ligand, interleukin-1α, and interleukin-1β in the aqueous humor of patients with open angle glaucoma using multiplex bead analysis

PURPOSE

Various cytokines, including tumor necrosis factor-alpha (TNF-α), Fas ligand (FasL), interleukin-1α (IL-1α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), contribute to the pathogenesis of primary open angle glaucoma (POAG). The present study was set to measure these cytokines in the aqueous humor of patients with POAG and in control subjects using multiplex bead analysis.

METHODS

Twenty-five patients with POAG and 29 control subjects were enrolled in this case-control study. Aqueous humor concentrations of the cytokines (IL-1 α, IL-1 β, IL-6, FasL, and TNF- α) were measured using multiplex bead analysis.

RESULTS

Mean aqueous humor levels of IL-6 were significantly lower in patients with POAG compared to the control subjects (9.3±23.7 versus 55.3±94.4 pg/ml; p=0.002). No significant difference in the aqueous humor concentration of IL-1β was found between patients with POAG and control subjects (0.5±0.8 versus 0.4±0.8 pg/ml; p=0.85.) Concentrations of IL-1α, TNF-α, and FasL were below limits of detection. No significant correlation was found between IL-6 concentration and age, duration of disease, cup/disc ratio, or mean deviation.

CONCLUSIONS

In the present study, we found significantly lower concentrations of IL-6 in the aqueous humor of patients with POAG.

Accuracy of matching optic discs with visual fields: the European Structure and Function Assessment Trial (ESAFAT)

PURPOSE

To determine the ability of ophthalmologists across Europe to match stereoscopic optic disc photographs to visual fields of varying severity.

DESIGN

Evaluation and comparison of 2 diagnostic tests.

PARTICIPANTS

A total of 109 of 260 invited ophthalmologists in 11 European countries. These had participated in the previous European Optic Disc Assessment Trial (EODAT), a trial on glaucoma diagnostic accuracy based on optic discs only.

METHODS

Each participant matched stereo optic disc photographs of 40 healthy and 48 glaucomatous eyes to a visual field chosen from 4 options per disc. The 4 presented visual fields included the corresponding one and 3 other visual fields, varying in severity. The matching accuracy and any inaccuracy per disease severity were calculated. Classification accuracy (as glaucomatous or healthy) was compared with EODAT data. Duplicate slides allowed for the assessment of intraobserver agreement.

MAIN OUTCOME MEASURES

Accuracy of matching optic discs with their corresponding visual field and of classifying them as healthy or glaucomatous; intraobserver agreement (κ).

RESULTS

The overall accuracy of ophthalmologists for correctly matching stereoscopic optic disc photographs to their visual fields was 58.7%. When incorrectly matched, the observers generally overestimated the visual field severity (P<0.001), notably in eyes with early glaucoma. The intraobserver agreement was, on average, moderate (0.52).

CONCLUSIONS

European ophthalmologists correctly matched stereoscopic optic disc photographs to their corresponding visual field in only approximately 59% of cases. In most mismatches, the clinicians overestimated the visual field damage.

[Transient visual deterioration by exposure to cold, phacic anterior chamber lens and forme fruste keratoconus. How can this be explained?]

This article reports on a 41-year-old male patient with forme fruste keratoconus and intolerance to contact lenses. An iris-supported intraocular lens was inserted in this eye with initially satisfactory results. During wintertime the patient coached a team of biathletes even in very low temperatures and/or windy conditions and after 2-3 h experienced a deterioration of vision in this eye. The contralateral eye with a contact lens never gave any such problems in this cold environment. Several factors might be responsible for this deterioration of vision. A very low outside temperature with or without wind induces evaporation of the tear fluid resulting in a more viscous lipid content than in warm conditions. A thin cornea facilitates faster cooling of the aqueous humor and less warming of the aqueous humor due to a deep anterior chamber where the warming iris is more distant from the cornea and partially covered by the optic and haptic of the implanted lens both of which have low heat transmission and slower exchange of the aqueous humor via the small peripheral iridotomy in comparison to the pupil which is covered by the implanted lens. Populations, such as Inuits and Mongolians who permanently live in cold environments, have developed shallow anterior chambers during evolution which protects the cornea from the cold due to the reduced distance from the warming iris to the cornea. In retrospect the implantation of a refractive lens into the posterior chamber would probably have been the better choice in this particular patient constellation.

Role of functional single nucleotide polymorphisms of MMP1, MMP2, and MMP9 in open angle glaucomas

PURPOSE

Matrix metalloproteinases (MMPs) play an essential role in the turnover of the extracellular matrix and cellular behavior. MMP1, MMP2, and MMP9 have previously been implicated in the pathogenesis of primary open angle glaucoma (POAG) and open angle glaucoma secondary to exfoliation syndrome (XFG), respectively. Functional gene polymorphisms of these MMPs such as MMP1 -1607 1G/2G (rs1799750), MMP2 -1306 C/T (rs243865), MMP2 -1575 G/A (rs243866), and MMP9 Q279R (rs17576) are thus plausible candidates as risk factors for open angle glaucomas. The purpose of the present study was to investigate hypothesized associations between these polymorphisms and the presence of POAG and XFG in a Caucasian population.

METHODS

The present case-control study included 322 patients with POAG, 202 patients with XFG, and 248 control subjects. Genotyping of polymorphisms was done using polymerase chain reaction.

RESULTS

No significant differences in either genotype distributions or allelic frequencies of MMP1 -1607 1G/2G, MMP2 -1306 C/T, MMP2 -1575 G/A, and MMP9 Q279R were found between patients with POAG and control subjects and patients with XFG and control subjects, respectively (p>0.05). The presence of POAG or XFG was not predicted by any of the investigated polymorphisms.

CONCLUSIONS

Our data suggest that the MMP1 -1607 1G/2G, MMP2 -1306 C/T, MMP2 -1575 G/A, and MMP9 Q279R polymorphisms themselves are unlikely major risk factors among Caucasian patients with either POAG or XFG.

Determination of uric acid concentrations in human tear fluid, aqueous humour and serum

PURPOSE

The aim of this investigation was to assess and compare levels of uric acid in human tear fluid, aqueous humour and serum in cataract patients in order to obtain information about uric acid-dependent antioxidative status.

METHODS

Reflex tear fluid, aqueous humour and serum were obtained from 103 cataract patients (52 women, 51 men). Uric acid was determined by a reversed phase chromatographic method with electrochemical detection. The Randox test was used to measure the contribution of uric acid to the total antioxidative status (TAS) of these body fluids.

RESULTS

Mean concentrations of uric acid were 20 +/- 8 microg/ml in tear fluid, 18 +/- 6 microg/ml in aqueous humour and 58 +/- 15 microg/ml in serum. Significantly less uric acid was found in tear fluid (p < 0.01) and aqueous humour (p < 0.01) in female cataract patients compared with male cataract patients. There was a significant positive correlation between uric acid content in tear fluid, aqueous humour and serum, respectively (p < 0.01). The contribution of uric acid to TAS (Randox test) amounted to 38% in tear fluid, 10% in aqueous humour and 37% in serum.

CONCLUSIONS

Uric acid was found in comparable amounts in tear fluid and aqueous humour, but these were two- to threefold lower than in serum. Female cataract patients had lower uric acid values in tear fluid and aqueous humour compared with male cataract patients. Uric acid is an important antioxidant, as proven by its contribution to TAS as determined by the Randox test. The precise role of uric acid in the antioxidative reactions in tear fluid and aqueous humour is still under debate.

Plasminogen activator inhibitor-1 4G/5G gene polymorphism and primary open-angle glaucoma

PURPOSE

Alterations of the plasmin system have been suggested to participate in the multifactorial pathogenesis of primary open-angle glaucoma (POAG). The main physiological inhibitor of the plasmin system is plasminogen activator inhibitor-1 (PAI-1), which leads to decreased degradation of extracellular material. Interestingly, elevated PAI-1 levels in the aqueous humor of patients with POAG have been reported. A common polymorphism within the promoter region (PAI-1 4G/5G) has previously been shown to reduce the gene transcription rate of PAI-1. The purpose of the present study was to investigate a hypothesized association between PAI-1 4G/5G and the presence of POAG in a Caucasian population.

METHODS

The present case-control study comprised 212 unrelated patients with POAG and 212 healthy control subjects, matched for age and sex. Genotyping of PAI-1 4G/5G polymorphisms was done using polymerase chain reaction.

RESULTS

Allelic frequencies and genotype distributions of PAI-1 4G/5G did not significantly differ between patients with POAG and control subjects (PAI-1 4G/5G: 29.7% versus 29.7%). Presence of the PAI-1 4G-allele was associated with a nonsignificant odds ratio of 0.98 (95% confidence interval: 0.74-1.30) for POAG.

CONCLUSIONS

Our data suggest that PAI-1 4G/5G itself is unlikely to be a major risk factor among Caucasian patients with POAG.

Lysyl oxidase-like protein 1 (LOXL1) gene polymorphisms and exfoliation glaucoma in a Central European population

PURPOSE

Exfoliation syndrome (XFS) is characterized by an accumulation of abnormal extracellular material in the anterior part of the eye that frequently leads to increased intraocular pressure and glaucomatous optic neuropathy. Recently, two non-synonymous polymorphisms (rs1048661 G>T and rs3825942 G>A) of lysyl oxidase-like protein 1 (LOXL1), a monoamine oxidase that catalyzes the polymerization of tropoelastin to elastin, were found to be associated with increased risk for XFS and exfoliation glaucoma (XFG). The aim of the present study was to investigate the role of these LOXL1 variants in a Central European cohort of Caucasian patients with XFG.

METHODS

The present case-control study comprised of 167 unrelated patients with XFG and 170 control subjects. Genotyping of the LOXL1 rs1048661 and rs3825942 polymorphisms was done using polymerase chain reaction.

RESULTS

The frequency of allele G of rs1048661 as well as rs3825942 was significantly higher in patients than in controls (rs1048661: 0.841 in patients versus 0.669; p<0.001; rs3825942: 0.994 in patients versus 0.817; p<0.001). Odds ratios of 52.1 (95% confidence interval [CI]: 13.85-195.6) and 14.67 (95% CI: 3.81-56.2), respectively, were calculated for the two high-risk haplotypes GG and TG compared to the haplotype GA.

CONCLUSIONS

Our data confirm the previously reported association between LOXL1 polymorphisms and XFG and extend our knowledge to a Central European population.

[Myopia and glaucoma]

The question is whether there is an increased risk to develop glaucoma in co-existing myopia. The different kinds of glaucoma dealing with this problem are described. The highly myopic eye with increased axial length shows many structural changes. Especially the changes of the optic nerve head in a highly myopic eye make it very difficult to differentiate between a beginning glaucoma and a normal structure or to define a progression of glaucomatous changes. The visual field defects are often close to fixation and may reduce visual acuity and therefore the quality of life of these usually younger patients. An increase of the thickness of the lens induced by senile cataract, drugs or diabetes mellitus, a forward shift of the lens or the iris-lens-diaphragm will lead to refractive myopia and may provoke an angle closure glaucoma. Pigmentary glaucoma occurs in younger patients in connection with low or medium myopia and more rapidly destroys the optic nerve head due to higher intraocular pressure values in comparison to the primary open-angle glaucoma. After refractive surgeries of myopic eyes one has to expect different kinds of glaucoma (steroid induced, pupillary block, angle closure). Due to the increased risk to develop glaucoma patients especially with high myopia are advised to consult their ophthalmologist on a regular basis.

Glaukom und oxidativer Stress

BACKGROUND

Primary open-angle glaucoma (POAG) is a multifactorial disease, in which aging, race, genetic disposition, vascular status, probably inflammation, and maybe oxidative stress may play a specific role. We wanted to know if by using a common test for a specific oxidative stress product differences would be found in the aqueous humor and serum of patients with POAG, cataract without pseudoexfoliation, cataract with pseudoexfoliation, and volunteers without ocular disease.

PATIENTS AND METHODS

We examined the aqueous humor of 33 patients with POAG, 111 patients with cataract without pseudoexfoliation, 39 patients with cataract and pseudoexfoliation syndrome and the serum of all three groups plus of 43 volunteers without ocular disease. Malondialdehyde as an oxidative stress product of peroxidation of lipids was proven by thiobarbituric acid-reacting substances (TBARS).

RESULTS

The amount of TBARS is given in micromol/l: (1) in the serum of the group with cataract 1.176, with cataract and pseudoexfoliation 1.019, with POAG 0.992, and with healthy eyes 0.983; (2) in the aqueous humor of the group with cataract 0.279, with cataract and pseudoexfoliation 0.274, and with POAG 0.298. There were no statistically significant differences of TBARS (p<0.05) in either the aqueous humor or in the serum of patients with POAG in comparison to those patients without POAG. However, there was a significantly positive correlation between the values in the serum and the aqueous humor.

CONCLUSION

For the first time malondialdehyde as a product of lipid peroxidation was determined in the aqueous humor of glaucomatous eyes. With the TBARS method used in our study, it was not possible to detect statistically significant differences of the lipid peroxidation product malondialdehyde between patients with or without POAG. It has to be taken into account that the cataract of the patients in the control group might be a disease per se caused by at least a certain amount of oxidative stress and that these subjects might therefore not be ideal as a control group.

New Insights into Ophthalmology: Introduction of SELDI-TOF in Combination with Molecular Modelling for the Analysis of Aqueous Humour. Principle and First Results

We present the introduction of a new generation of techniques for early and specific diagnosis of inflammatory, immune and degenerative eye diseases. We concentrate on the applications of the SELDI-TOF (Surface enhanced laser desorption ionisation - time of flight) mass spectroscopy in combination with molecular modelling and visualization for the analysis of the aqueous humour. For our study we used aqueous humour from 25 patients undergoing cataract operation. SELDI-TOF consists on one part of an apparatus allowing the laser bombarding of molecules on a solid surface and on the other part on a system which measure the time of flight of the molecules. During the measurement the molecules are liberated from the matrix and carried to the detector. Specific proteins can be identified by the characteristic peaks of the spectrogram. Albumin and gamma-globulin were found to a considerable extend in the aqueous humour. An increased amount has been detected in inflammatory humour. The quantity may reflect some underlying complications such as inflammation and animate for further research on the spectrum of proteins and peptides released by underlying eye disorder. SELDI-TOF delivers characteristic peptide mass fingerprints, which can be used as input for the prediction of the tertiary protein structure with homology modelling. Structural deviations between a genuine protein and a mutated can be an indicator about the underlying disease, paving the way for successful diagnostic and therapy. The combination of two new technologies namely SELDI-TOF and molecular modelling may offer a broad spectrum for the differential diagnosis of some eye diseases.

Efficacy of contact lens storage solutions against different acanthamoeba strains

PURPOSE

This study was undertaken in order to determine the susceptibility of acanthamoebae to various contact lens disinfecting systems, with respect to type of disinfectant and exposure time.

METHODS

Ten contact lens solutions, including one new system, were tested for their effectivities against cysts of three Acanthamoeba strains. Of main interest was an incubation time of 8 hours (overnight disinfection) and cyst quantities of 10 and 10, respectively.

RESULTS

Boston Advance (polyaminopropyl biguanide 0.0005%, chlorhexidine 0.003%) for the storage of rigid gas permeable contact lenses destroyed the cysts of all strains at either concentration within one hour of exposure. Meni Care Plus (polyhexamethylene biguanide 0.0005%) also destroyed 10 cysts of all strains, however, 10 cysts only of two strains within one hour; after an exposure time of 8 hours all cysts were killed. The disinfecting solutions for soft contact lenses did not kill 10 cysts of either strain after 8 hours of incubation time.

CONCLUSION

Two of the tested contact lens solutions (the ones for rigid gas permeable lenses) destroyed the cysts of all strains. One of these, containing a combination of two amoebicidal ingredients even after only one hour of exposure time.

Methylenetetrahydrofolatereductase (MTHFR) 677C>T polymorphism and open angle glaucoma

PURPOSE

Increased plasma homocysteine levels have been found in patients with primary open angle glaucoma (POAG) and glaucoma secondary to pseudoexfoliation syndrome (PEXG). A common polymorphism of the methylenetetrahydrofolatereductase (MTHFR 677C>T) leads to moderately elevated plasma homocysteine levels particularly under conditions of impaired folate status. It was the aim of this study to investigate a hypothesized association between this polymorphism and the presence of either POAG or PEXG.

METHODS

The present retrospective case-control study included a total of 553 participants comprising 204 patients with POAG, 138 patients with PEXG, and 211 control subjects. Genotyping for the MTHFR 677C>T polymorphism was performed by polymerase chain reaction (PCR).

RESULTS

No significant difference in the genotype distribution of the MTHFR 677C>T polymorphism was found between control subjects and patients with POAG or PEXG. The prevalence of the MTHFR 677TT genotype was 6.9% in patients with POAG, 11.6% in patients with PEXG, and 9.5% in control subjects.

CONCLUSIONS

The present data suggest that the MTHFR 677C>T polymorphism itself is not a major genetic risk factor for POAG and PEXG in a central European population.

One- and two-step hydrogen peroxide contact lens disinfection solutions against Acanthamoeba: How effective are they?

PURPOSE

Effective contact lens disinfection solutions are important to keep the storage case free of acanthamoebae and thus prevent an infection of the eye. The aim of our study was to evaluate the effectivity of two new one-step hydrogen peroxide disinfecting solutions against Acanthamoeba spp. and compare it to the effectivity of other commercially available systems.

METHODS

Nine one-step 3% hydrogen peroxide systems including the new systems Silver Sept (platinum and silver disk for intensifying disinfection) and Blue Vision (newly composed catalytic tablet) and 2 two-step systems (0.6 and 3.0% H(2)O(2)) were tested for their effectivity against cysts of two Acanthamoeba keratitis isolates at different concentrations.

RESULTS

After a soaking time of 8 h (overnight soaking of contact lenses) the 2 two-step systems completely destroyed the cysts of both Acanthamoeba strains, even at the highest concentration of cysts tested. The nine tested one-step systems showed weaker effects. The new Blue Vision system was able to eradicate the cysts of one strain at the low concentration of cysts.

CONCLUSIONS

One-step hydrogen peroxide systems do not have sufficient effects on Acanthamoeba cysts and therefore may not protect the contact lens user from a possible infection of the eye. Further development of tablets like the ones used in the Blue Vision system may result in better cysticidal effects for one-step systems.

Opacification of a silicone intraocular lens caused by calcium deposits on the optic

We describe opacification of a plate-haptic silicone intraocular lens (IOL) caused by calcification in a diabetic patient with asteroid hyalosis. The IOL was explanted 48 months after uneventful phacoemulsification because opacification of the posterior surface was causing significant visual disturbance. Light and scanning electron microscopy and x-ray spectrometry of the explanted IOL showed the opacification consisted mainly of calcium and phosphate, presumably hydroxyapatite, in the form of precipitations on the posterior surface of the optic.

Corneal degeneration after silicone oil tamponade in a photorefractive keratectomy treated eye

Three years after uneventful excimer laser photorefractive keratectomy in both eyes, a 34-year-old man sustained a perforating injury in the left eye. The severe injury, followed by endophthalmitis and retinal detachment, necessitated vitrectomy, lensectomy, and an internal tamponade with silicone oil. One month after the accident and operations, disk-shaped corneal edema corresponding to the laser treatment zone appeared. The edematous region showed a circular, ring-like epithelial thickening at the borders and central corneal epithelial erosion. The anterior stroma developed a central opacity that was separated by a clear rim from the developing silicone-oil keratopathy with the typical band shape.

[A clinico-pathological case report of necrotizing ulcerating keratopathy due to topical anaesthetic abuse]

BACKGROUND

Topical anesthetic abuse is rare, but difficult to diagnose since most patients deny its use and the clinical changes are very similar to other corneal diseases.

CASE REPORT

A 45-year-old medical doctor with a 30-year history of soft contact lens wear and recurrent corneal erosion was admitted to our clinic with a ring-shaped keratitis and intense ocular pain. A corneal smear was negative for bacterial infections and acanthamoeba but the contact lens box contained a few dead acanthamoeba and many cocci. Due to the clinical findings and the acanthamoeba found in the contact lens box acanthamoeba keratitis was diagnosed and treatment with gentamycin, pentamidine isethionat (Brolene((R))) and hexamidine (Desomedine((R))) was started. The clinical appearance did not change for 6 weeks after onset of treatment and a perforating corneal transplantation was performed for pain relief and visual rehabilitation. An iris ectropion lacking iris motility and dense cataract developed within 5 weeks and the patient admitted on direct questioning to having taken topical anesthetic (oxybuprocain) by self-medication. The histological investigation revealed few inflammatory cells. The epithelium was largely missing and few vital cells could be found in the stroma and the endothelial cell layer. Acanthamoeba could not be detected in the tissue.

CONCLUSION

Topical anesthetic abuse can mimic different corneal diseases and be difficult to diagnose if the patient denies its use. In cases of keratitis with no response to treatment and strong ocular pain, topical anesthetic abuse should be considered.

Viability of Acanthamoeba after exposure to a multipurpose disinfecting contact lens solution and two hydrogen peroxide systems

BACKGROUND/AIM

Contact lens cases contaminated with Acanthamoeba are a major risk factor for an infection of the eye. In this study the anti-Acanthamoeba activity of three different contact lens storage solutions was tested.

METHODS

A new multipurpose contact lens storage solution (Meni Care Plus) and a two step (Titmus H(2)O(2)) and one step (Oxysept Comfort) hydrogen peroxide system were tested for their effects on trophozoites and cysts of three different Acanthamoeba species: A castellanii, A hatchetti, and A lenticulata.

RESULTS

After a soaking time of 8 hours (overnight soaking of contact lenses) the Titmus H(2)O(2) 0.6% solution showed very good amoebicidal effects, while Oxysept Comfort 3% H(2)O(2) could not effectively destroy the cysts of any of the three tested species. Viable cysts of the species A lenticulata and A hatchetti were still present after exposure to Meni Care Plus (0.0005% PHMB) for 8 hours.

CONCLUSION

Not all of the three tested contact lens storage solutions have sufficient amoebicidal effects. The two step peroxide system Titmus H(2)O(2) is a very effective disinfectant contact lens solution in order to avoid a possible Acanthamoeba infection of the eye.

Microwave treatment of contact lens cases contaminated with acanthamoeba

PURPOSE

Microbially contaminated contact lens cases are a predisposing risk factor for Acanthamoeba keratitis. Several findings have shown that microwave irradiation kills the six Food and Drug Administration test challenge microorganisms. We aimed to determine what effect microwave irradiation has on Acanthamoeba trophozoites and cysts.

METHODS

Different types of contact lens cases were contaminated with trophozoites and cysts of three different Acanthamoeba species (A. comandoni, A. castellanii, A. hatchetti) and were exposed to microwave irradiation for 3, 5, and 8 minutes, respectively.

RESULTS

Trophozoites, as well as cysts of the different Acanthamoeba strains, were effectively killed, even by only 3 minutes of microwave irradiation, and there were no negative effects of irradiation on the contact lens cases themselves.

CONCLUSION

We demonstrate that microwave treatment is a very effective, easy, and cheap method to keep contact lens cases free of Acanthamoeba, thus considerably reducing the risk of an Acanthamoeba keratitis.