Acanthamoeba keratitis and contact lens wear

Acanthamoeba keratitis is a rare but serious complication of contact lens wear that may cause severe visual loss. The clinical picture is usually characterised by severe pain, sometimes disproportionate to the signs, with an early superficial keratitis that is often misdiagnosed as herpes simplex virus (HSV) keratitis. Advanced stages of the infection are usually characterised by central corneal epithelial loss and marked stromal opacification with subsequent loss of vision. In this paper, six cases of contact lens-related Acanthamoeba keratitis that occurred in Australia and New Zealand over a three-year period are described. Three of the patients were disposable soft lens wearers, two were hybrid lens wearers and one was a rigid gas permeable lens wearer. For all six cases, the risk factors for Acanthamoeba keratitis were contact lens wear with inappropriate or ineffective lens maintenance and exposure of the contact lenses to tap or other sources of water. All six patients responded well to medical therapy that involved topical use of appropriate therapeutic agents, most commonly polyhexamethylene biguanide and propamidine isethionate, although two of the patients also subsequently underwent deep lamellar keratoplasty due to residual corneal surface irregularity and stromal scarring. Despite the significant advances that have been made in the medical therapy of Acanthamoeba keratitis over the past 10 years, prevention remains the best treatment and patients who wear contact lenses must be thoroughly educated about the proper use and care of the lenses. In particular, exposure of the contact lenses to tap water or other sources of water should be avoided.

Change in the geometry of positive- and negative-powered soft contact lenses during wear

Contact lens wear causes mutual interactions between the ocular surface and the lens, which may affect comfort as well as vision. The aim of this study was to examine deformations in modern positive- and negative-powered silicone hydrogel soft contact lenses (SiH SCLs) after 7 days of continuous wear. This pre-post interventional study included 64 eyes: 42 eyes with myopia of -3.00 D and 22 eyes with hyperopia of +3.00 D. All patients underwent general ophthalmic examination, corneal topography/tomography, total corneal and epithelial thickness mapping, and specular microscopy before and after the wearing period. SiH SCLs made of senofilcon A were worn continuously for 7 days on all eligible eyes. The geometry of the new and used lenses was measured 3 to 6 minutes after removal in two perpendicular planes using a custom-made swept source optical coherence tomography (SS-OCT) system for in vitro measurements. The anterior and posterior radii of curvature decreased in -3.00 D lenses in two perpendicular planes. This effect correlated significantly with average keratometry of the cornea. Sagittal lens height was lower in +3.00 D lens after wear, which correlated moderately with the corneal sagittal height. A significant decrease in central corneal epithelial thickness was observed after wearing +3.0 D lenses. In conclusion, SiH SCLs made of senofilcon A undergo minor deformations after 7-day continuous wear. Geometry modifications are different for -3.00 D and +3.00 D lenses, and they imitate the shape of the anterior eye surface. These geometric changes are accompanied by a decrease in the central thickness of corneal epithelium after +3.00 D lens wear.

Overnight corneal swelling with high and low powered silicone hydrogel lenses

PURPOSE

To compare central corneal swelling after eight hours of sleep in eyes wearing four different silicone hydrogel lenses with three different powers.

METHODS

Twenty-nine neophyte subjects wore lotrafilcon A (Dk, 140), balafilcon A (Dk, 91), galyfilcon A (Dk, 60) and senofilcon A (Dk, 103) lenses in powers -3.00, -10.00 and +6.00 D on separate nights, in random order, and on one eye only. The contra-lateral eye (no lens) served as the control. Central corneal thickness was measured using a digital optical pachometer before lens insertion and immediately after lens removal on waking.

RESULTS

For the +6.00 D and -10.00 D, lotrafilcon A induced the least swelling and galyfilcon A the most. The +6.00 D power, averaged across lens materials, induced significantly greater central swelling than the -10.00 and -3.00 D (Re-ANOVA, p<0.001), (7.7±2.9% vs. 6.8±2.8% and 6.5±2.5% respectively) but there was no difference between -10.00 and -3.00 D. Averaged for power, lotrafilcon A induced the least (6.2±2.8%) and galyfilcon A the most (7.6±3.0%) swelling at the center (Re-ANOVA, p<0.001). Central corneal swelling with +6.00 D was significantly greater than -10.00 D lens power despite similar levels of average lens transmissibility of these two lens powers.

CONCLUSIONS

The differences in corneal swelling of the lens wearing eyes are consistent with the differences in oxygen transmission of the silicone hydrogel lenses. In silicone hydrogel lenses central corneal swelling is mainly driven by central lens oxygen transmissibility.

Short-term corneal changes with gas-permeable contact lens wear in keratoconus subjects: a comparison of two fitting approaches

PURPOSE

To evaluate changes in anterior corneal topography and higher-order aberrations (HOA) after 14-days of rigid gas-permeable (RGP) contact lens (CL) wear in keratoconus subjects comparing two different fitting approaches.

METHODS

Thirty-one keratoconus subjects (50 eyes) without previous history of CL wear were recruited for the study. Subjects were randomly fitted to either an apical-touch or three-point-touch fitting approach. The lens' back optic zone radius (BOZR) was 0.4mm and 0.1mm flatter than the first definite apical clearance lens, respectively. Differences between the baseline and post-CL wear for steepest, flattest and average corneal power (ACP) readings, central corneal astigmatism (CCA), maximum tangential curvature (KTag), anterior corneal surface asphericity, anterior corneal surface HOA and thinnest corneal thickness measured with Pentacam were compared.

RESULTS

A statistically significant flattening was found over time on the flattest and steepest simulated keratometry and ACP in apical-touch group (all p<0.01). A statistically significant reduction in KTag was found in both groups after contact lens wear (all p<0.05). Significant reduction was found over time in CCA (p=0.001) and anterior corneal asphericity in both groups (p<0.001). Thickness at the thinnest corneal point increased significantly after CL wear (p<0.0001). Coma-like and total HOA root mean square (RMS) error were significantly reduced following CL wearing in both fitting approaches (all p<0.05).

CONCLUSION

Short-term rigid gas-permeable CL wear flattens the anterior cornea, increases the thinnest corneal thickness and reduces anterior surface HOA in keratoconus subjects. Apical-touch was associated with greater corneal flattening in comparison to three-point-touch lens wear.

[The clinical and functional characteristics of the course of the dry eye syndrome associated with soft contact lens wear]

The study deals with the clinical course of the dry eye syndrome (DES) associated with soft contact lens (SCL) wear. One hundred and two subjects (204 eyes) aged 18 to 38 years were examined for DES. The course of the disease was compared among men and women at Stage 1, among hydrogel and silicone hydrogel SCL wearers at Stage 2, among the patients who had worn SCL for a year or longer and SCL nonusers. The subjects who wear SCL from various materials develop DES significantly more frequently than do SCL nonusers. This pathology develops in both women and men. DES develops with equal frequencies in both hydrogel and silicone hydrogen SCL wearers. The individuals wearing SCL for a year or longer are much more likely to develop DES.

Limbal stem cell study in contact lens wearers

The effect of soft contact lens on the limbal stem cells was assessed in 30 contact lens wearers, 19 controls, and 17 cases known to cause limbal stem cell deficiency. Different results were seen as compared to controls in all the four quadrants, but more severe in cases known to cause limbal stem cell deficiency.

[Influence of long-term contact lens wear on the cornea according to the data confocal microscopy]

The paper presents the results of a comparative study of corneal morphological changes by lifetime confocal miscroscopy in the long-term use of various types of contact lenses (CLs). Twenty-two patients (44 eyes) were examined, of them 8 patients (16 eyes) had worn soft CLs (SCLs) for 10-25 years (mean 17 years). 8 (16 eyes) had used hard CLs (HCLs) made of polymethyl metacrylate for 17-30 years (mean 23 years), 6 (12 eyes) had worn HCLs for 15 to 30 years (mean 20 years), hard gas-permeable CLs (HGCLs) over the past 5-15 years. The findings suggest that long-term wear of corrective CLs may lead to significant structural impairments in different corneal layers. The most characteristic changes are different types of epitheliopathies and the emergence of the signs of stromal degeneration with formation of deposits. According to our evidence, the likelihood of the detected changes increases with the long use of SCLs and reduces with the wear of HCLs, HGCLs in particular, which allows the authors to recommend that SCLs be changed to HGCLs after long (more than 10-15-year) contact correction.

[Pseudomonas aeruginosa keratitis associated with the use of last generation contact lens made of silicone hydrogel: case report]

We report the case of a female patient, 56-year-old housewife, for the first time user of last generation contact lenses: Lotrafilcon B, which presented a severe corneal ulcer by Pseudomonas aeruginosa in hev left eye and subsequently required keratoplasty. Initially she reported pain and arrived at the emergency department with red eye, corneal central ulcer of three days of evolution and hypopion. Initially she received topic mydriatic drugs and prednisolone at 1%. At the next day the ophthalmologycal exam showed hypopion at 5% and a central severe ulcer greater than 3 mm in diameter with sharp edges and mucopurulent secretion. The treatment was changed to moxifloxacin and natamycin. The microbiological analysis performed in two laboratories yielded Aspergillus sp. and Pseudomonas aeruginosa sensitive to ciprofloxacin, tobramycin, gentamicin and moxifloxacin. The presence of Aspergillus was interpreted as a pollution lens case and likely colonization of the cornea because of the patient good performance. After four months although improving she required corneal transplantation. Photographic documentation of the case under illumination with slit lamp is presented.

The effect of senofilcon A contact lenses compared to habitual contact lenses on ocular discomfort during exposure to a controlled adverse environment

OBJECTIVE

Contact lens wear is often associated with signs and symptoms of ocular dryness. These drying effects can be exacerbated by certain environmental factors such as low humidity, wind, and visual tasks. The objective of the study was to compare the ability of senofilcon A contact lenses to subjects' habitual contact lenses to provide relief from the subjects' perceived ocular discomfort during contact lens wear in adverse environmental conditions.

RESEARCH DESIGN AND METHODS

Eleven subjects completed a single-center, double-masked, randomized, cross-over, pilot clinical trial. At the qualification visit, and subsequently wearing senofilcon A study lenses (ACUVUE OASYS Brand Contact Lenses with HYDRACLEAR Plus) and control (habitual) lenses at the following visits, subjects underwent a total of three 75-min Controlled Adverse Environment (CAE) exposures. The primary efficacy variable measured during the 2-week, 3-visit trial was subject-reported ocular discomfort during CAE exposure measured on a five-point scale from 0 (none) to 4 (worst). The endpoint of ocular discomfort was evaluated using a two-sided t-test based on a longitudinal linear mixed model. Lenses were also evaluated for safety, and all adverse events were monitored.

RESULTS

Subjects reported a significantly better mean comfort score when wearing senofilcon A contact lenses (1.62 +/- 0.71 units) compared to the mean comfort score reported when wearing habitual lenses (2.21 +/- 0.80 units) over the course of an entire CAE exposure (p = 0.0068). During exposure, senofilcon A lenses also yielded significantly better mean overall discomfort scores versus no lenses (2.73 +/- 0.79 points, p < 0.0001).

CONCLUSIONS

Senofilcon A contact lenses provided greater relief of subjective ocular discomfort associated with lens wear in adverse environmental conditions than that afforded by both the habitual lenses of contact lens wearers as well as with no contact lens wear. These results should be verified in a larger, appropriately-powered study.

Risk factors for corneal infiltrates with continuous wear of contact lenses

PURPOSE

To describe the factors associated with symptomatic corneal infiltrates in a postmarket surveillance study of continuous wear contact lenses.

METHODS

Patients intending to wear lotrafilcon A lenses continuously for 30 days and nights were registered in a 1-year study at 131 clinical sites. A self-administered questionnaire was used to gather demographic and other data at baseline. The severity of the incidence of corneal infiltrative events during the year-long study was graded by an independent adjudication committee.

RESULTS

Of 6245 lens wearers, 163 were reported to have symptomatic corneal infiltrative events (2.6%). In 159 wearers, the infiltrates were judged to be lens-related (2.5%). Age < or =25 years and >50 years was significantly associated with the development of corneal infiltrates (< or =25 years OR = 1.75, 95% CI = 1.24-2.48 and >50 years OR = 2.04, 95% CI = 1.40-2.98). Ametropia of > or =5.00 D was significantly associated with corneal infiltrates (OR = 1.60, 95% CI = 1.08-2.37). Study participants who typically wore lenses for >21 consecutive days and nights were significantly less likely to have infiltrates than those who wore lenses for fewer consecutive days and nights (OR = 0.43, 95% CI = 0.24-0.75). Smoking concurrent with contact lens wear was weakly associated with corneal infiltrates (OR = 1.47, CI = 0.99-2.18).

CONCLUSIONS

Patient age, degree of refractive error, and failure to achieve the intended wearing schedule were associated with development of symptomatic corneal infiltrative events.

Impaired innate immunity of ocular surface is the key bridge between extended contact lens wearing and occurrence of Acanthamoeba keratitis

Acanthamoeba keratitis is a progressive, sight-threatening corneal disease. Extended wearing contact lens is one of predisposed factors. Early studies mostly focused on "improper contact-lens hygiene", which described that contact lens wearers have more opportunities to contact with pathogens directly and prone to get A. keratitis. However, improper contact-lens hygiene can not explain the phenomenon that Acanthamoeba protozoon were found in normal individuals' lens-cases. So there might be other factors related with A. keratitis. Recently, more attention has been paid on the influence of extended wearing contact lens on the innate immunity of ocular surface. It has been proven that in contact lens wearers the reactivity of polymorphonuclear leucocytes (PMNs) and the concentration of certain inflammatory mediators were significantly altered compared with that in non-lens wearers. Moreover, other studies showed the important contributions of innate immunity on occurrence and development of A. keratitis. With the contribution of extended wearing contact lens on immunity and the relation between innate immunity and Acanthamoeba, we suggest that the impaired innate immunity of ocular surface may be a key bridge between extended wearing contact lens and A. keratitis. With the impaired innate immunity caused by extended contact-lens wearing, the Acanthamoeba trophozoites and cysts could not be easily killed, therefore A. keratitis was occurred and aggravated. Understanding the immunological mechanism of extended contact lens wearing on the A. keratitis may give more contributions on the research of the disease, and facilitate the production of contact lens with much higher biocompatibility.

Corneal conjunctivalisation in long-standing contact lens wearers

BACKGROUND

There are many contact lens-related ocular surface disorders. Some can damage the limbal region where stem cells are thought to be located in its basal cell layer. This damage can result in destruction and a deficiency of corneal stem cells. One important sign of this complication is corneal conjunctivalisation. The purpose of this study is to describe clinical characteristics of a series of long-standing contact lens (CL) wearers with corneal conjunctivalisation (CC).

METHODS

In a one-year (March 2004 to March 2005) retrospective unmasked study, 591 CL clinical histories (195 new patients and 396 review patients) were analysed.

RESULTS

There were 24 eyes of 14 myopic patients (93 per cent women) with CC without a specific disease entity known to cause limbal stem cell deficiency (LSCD). Conjunctivalisation occurred in the inferior limbus of three eyes (12 per cent). Only four patients (28.6 per cent) reported previous ocular symptoms. All were myopic with a mean spherical equivalent of -8.80 +/- 5.00 (SD) dioptres (range from -1.75 to -21.50 D) and mean visual acuity 0.9 +/- 0.2 (range from 0.4 to 1.2). The mean years of CL wear was 17.6 +/- 8.5 (CI 95% 13.2 to 22; range six to 30). All were daily-wear patients with a mean daily-wear time of 12.5 +/- 1.8 hours per day (CI 95% 11.6 to 13.4).

CONCLUSION

Corneal conjunctivalisation is a contact lens-related complication in asymptomatic patients. Optometrists can play an important role in early diagnosis, education and management of these patients.

Inflammatory and Mechanical Complications Associated With 3 Years of up to 30 Nights of Continuous Wear of Lotrafilcon A Silicone Hydrogel Lenses

PURPOSE

To report the ocular complications occurring during a 3-year clinical trial of subjects wearing lotrafilcon A silicone hydrogel lenses for up to 30 nights of continuous wear.

METHODS

Nineteen sites enrolled 317 subjects (286 current wearers and 31 new wearers), who were dispensed lotrafilcon A lenses with 3 years of follow-up.

RESULTS

By the 1-month visit, continuous wear of up to 30 nights was recommended for 87% of subjects. The 27 lens-related adverse events included 15 (2.4%) eyes in year 1, seven (1.3%) eyes in year 2, and five (0.8%) eyes in year 3. Lens-related inflammatory events involved 12 (1.9%) eyes in year 1 and five (0.8%) eyes each in years 2 and 3. One third of the inflammatory events occurred in the first 3 months. Mechanical events included two superior epithelial arcuate lesions and one case of bilateral contact lens papillary conjunctivitis in years 1 and 2. No subjects experienced microbial keratitis during the 3-year trial. Two subjects with events discontinued from the trial.

CONCLUSIONS

These results show that the rate of contact lens adverse events occurring with lotrafilcon A is low in this cohort, with the highest likelihood occurring during the first 3 months of the study. There was a decrease in the rate of events during the later years of the study. Although clinicians should understand the likelihood of adverse inflammatory and mechanical events and their possible recurrence, the rate of these events may be lower in practice than previously reported.

Infectious keratitis

PURPOSE OF REVIEW

Infectious keratitis is a medical emergency. Improper management can lead to marked loss of vision. This review identifies recent trends in the study of infectious keratitis.

RECENT FINDINGS

A multicountry outbreak of Fusarium keratitis emphasizes that contact lens wear is a major risk factor for infectious keratitis. Acanthamoeba and fungal keratitis are the most expensive forms of infectious keratitis to treat. Noninvasive methods and molecular techniques have improved diagnosis of infectious keratitis. Fortified topical antibiotics and fluoroquinolones are still the mainstay of bacterial keratitis therapy. Voriconazole and new routes of administration of conventional antifungals appear promising for fungal keratitis. Antivirals and amelioration of host inflammatory response are promising for viral keratitis; the host response is also crucial in pathogenesis of Pseudomonas aeruginosa keratitis. Trauma-induced bacterial and fungal keratitis and contact lens-associated keratitis are preventable entities.

SUMMARY

Improved modalities of diagnosis and treatment have improved the outcome of infectious keratitis, but therapy of acanthamoebal, fungal and P. aeruginosa keratitis is still a challenge. Effective strategies must neutralize potential risk factors and counter host response overactivity without impairing killing of infecting microorganisms. Trauma-induced bacterial and fungal keratitis can be prevented.

Risk of corneal inflammatory events with silicone hydrogel and low dk hydrogel extended contact lens wear: a meta-analysis

PURPOSE

High Dk silicone hydrogel (SH) lenses have been shown to significantly decrease the risk of hypoxic complications compared to traditional low Dk hydrogels. However, the risks of inflammatory complications with SH compared to low Dk lenses are not as clear. A meta-analysis was performed to combine the relevant literature to evaluate the risks of corneal inflammatory events in users of SH and low Dk hydrogel extended wear lenses.

METHODS

A systematic search was conducted using online databases, unpublished meeting abstracts, and retrieval of other cited references presented or published between 1990 and February 2006. Each study was evaluated for quality in terms of the research question, and these quality assessments were used to determine which studies should be used in subgroup analyses. A generalized linear mixed model framework with an underlying Poisson distribution for the occurrence of events was employed to combine information from the included studies.

RESULTS

Twenty-three studies published or presented on either or both arms by February 2006 were selected for analysis. A total of 9,336 subjects and 18,537 eyes comprised the entire sample. Seven studies were published in the 1990s. Eighteen studies (78%) were prospective, and 11 (48%) used randomization. The follow-up ranged from 4 to 36 months, with a median of 12 months. The rates of infiltrates for low Dk hydrogels and SH lenses were 7.7 (2.2, 26.7) and 14.4 (4.3, 48.2) per 100 eye-years, respectively. In the subset of five best quality studies, the unadjusted risk ratio for corneal inflammatory events for SH lenses compared to low Dk lenses was 2.18 (p < 0.005). Across studies, adjusted risk ratios ranged from 2.18 to 2.23 (p < 0.05), with strong confounding between material and length of wear.

CONCLUSIONS

Based on published or presented studies between 1991 and 2006, there is approximately a twofold higher risk for corneal inflammatory events in users of SH lenses when typically worn for up to 30 days extended wear when compared with low Dk extended wear lenses when typically worn for 7 days extended wear. The increased risk cannot be definitively linked to SH lens materials because the effect of material on outcome is confounded by length of wear.

The epidemiology of contact lens related infiltrates

With estimated numbers of contact lens wearers worldwide exceeding 140 million, even complications with a low incidence will affect a significant number of individuals. Although contact lenses clearly have many advantages for wearers, certain risks have been associated with their use. Differences in risk for different types of contact lenses and wearing patterns have been demonstrated for both rare and common lens related complications. This review particularly focuses on the incidence and etiology of contact lens related corneal infection and inflammation. An understanding of the risks and contributory factors to these conditions is important for practitioners and will enable an informed choice of safer lens wear modalities, wear schedules, and hygiene regimes to be made.

Pseudomonas aeruginosa infection and inflammation during contact lens wear: a review

Infection and inflammation during contact lens wear is often associated with microbial contamination of lenses. Several different types of microbes that colonize lenses can lead to infection and inflammation, but the most common cause of infection (microbial keratitis; MK) remains the Gram-negative bacterium Pseudomonas aeruginosa. P. aeruginosa has a battery of cell-associated and extracellular virulence factors it can use to initiate and maintain infection. Its ability to produce proteases, to either invade or kill corneal cells, and to coordinate expression of virulence factors via quorum-sensing have been shown to be important during MK. Another important factor that contributes to the destruction of the cornea during MK is excessive activation of the host defense system. P. aeruginosa can activate several pathways of the immune system during MK, and activation often involves receptors on the corneal epithelial cells called toll-like receptors (TLRs). These TLRs recognize e.g., lipopolysaccharide or flagella from P. aeruginosa and activate the epithelial cells to produce inflammatory mediators such as cytokines and chemokines. These cytokines or chemokines recruit white blood cells, predominantly polymorphonuclear leukocytes, to the infection in order that they can phagocytose and kill the P. aeruginosa. However, continued recruitment and presence of these polymorphonuclear neutrophils and other white blood cells in the corneal tissue leads to destruction of corneal cells and tissue components. This can ultimately lead to scarring and vision loss.

Predictive factors for corneal infiltrates with continuous wear of silicone hydrogel contact lenses

OBJECTIVE

To estimate the cumulative probability and risk factors for developing corneal infiltrates after up to 3 years of continuous wear (CW) with lotrafilcon A lenses.

METHODS

Patients were fitted with lotrafilcon A lenses and followed up for 3 years. The main outcome variable was the first occurrence of any infiltrative event in either eye. Cox proportional hazards regression was used to model the probability of developing infiltrates as a function of demographic and biomicroscopy findings.

RESULTS

A total of 317 patients participated in this study. The Kaplan-Meier unadjusted cumulative incidence of a corneal infiltrate after CW was 5.7% (95% confidence interval [CI], 3.0%-8.4%) at the end of 1 year, 8.5% (95% CI, 5.2%-11.9%) at the end of 2 years, and 10.3% (95% CI, 6.6%-13.9%) at the end of 3 years. Corneal staining and limbal redness present in the affected eye on a previous visit were significantly associated with the development of an infiltrative event (hazard ratios, 7.23 and 3.18; P<.001 and P = .02, respectively).

CONCLUSIONS

Corneal staining and limbal redness may predict the subsequent development of an infiltrative event among CW contact lens patients. The probability of remaining free of any corneal infiltrates at the end of 3 years of CW of contact lenses was 89.7% (95% CI, 86.1%-93.4%).

A 12-month prospective clinical trial of comfilcon A silicone-hydrogel contact lenses worn on a 30-day continuous wear basis

PURPOSE

To evaluate the clinical performance of comfilcon A (Biofinity) during 12 months of continuous wear compared to other silicone-hydrogel lenses.

METHOD

Forty-five subjects were fitted in one eye with the comfilcon A (test) lens. For 22 subjects, the other eye was fitted with lotrafilcon A (group A) and for the remaining 23 subjects the other eye was fitted with balafilcon A (group B). Twelve-month data are presented on 48 measured variables.

RESULTS

There were no serious adverse events during the course of the study. A total of 33 subjects completed the study, with only 4 discontinuations for lens-related reasons, spread proportionately between the lenses. On preference scales, the test lens was superior to both control lenses for comfort (p<0.05) and overall preference (p<0.05) and in group A for vision (p<0.05). On grading scales, the test lens scored better than both control lenses for overall comfort (p<0.1 for group A, p<0.05 for group B), comfort during the day (p<0.05), end-of-day comfort (p<0.05) and overall preference (p<0.05), and better in group A for general vision quality (p<0.01), night vision quality (p<0.01) and handling (p<0.05). All lenses performed to a comparable degree on the basis of microcysts and corneal staining. There were significant differences between lenses in producing limbal redness (p<0.05), bulbar conjunctival hyperemia (p<0.1) and conjunctival NaFl staining (p<0.01) with the control lens in group A showing the greatest effect and the control lens in group B the least.

CONCLUSION

Comfilcon A offers performance advantages over first generation silicone-hydrogel materials for continuous wear.

Overnight Corneal Swelling With Silicone Hydrogel Contact Lenses With High Oxygen Transmissibility

PURPOSE

To compare central corneal swelling after 8 hours of sleep in eyes wearing 2 different silicone hydrogel lenses with high oxygen transmissibility.

METHODS

Twenty neophyte subjects were randomly assigned to wear a comfilcon A lens (CooperVision Inc) in one eye and a lotrafilcon A lens (CIBA Vision) in the contralateral eye for an 8-hour overnight period. The study was repeated with another 20 neophyte subjects wearing comfilcon A in one eye only and no lens in the contralateral control eye. Central corneal thickness was measured with optical pachometry before lens insertion, immediately after lens removal on waking, at 20 and 40 minutes, 1 hour, 2 hours and 3 hours.

RESULTS

There was no significant difference between the amount of overnight central corneal swelling induced by the 2 lenses (4.1% +/- 1.9% with comfilcon A vs. 4.0% +/- 1.7% with lotrafilcon A; P>0.05). The swelling of the comfilcon A lens-wearing eyes was significantly higher than that found in the non-lens-wearing contralateral eyes (4.5% +/- 2.1% vs. 3.0% +/- 1.7%; P<0.05).

CONCLUSIONS

The same amount of overnight corneal swelling was induced by the 2 study lenses. The higher overnight swelling observed with the comfilcon A lenses compared to the non-lens-wearing eyes is similar to that reported in the literature for studies using lotrafilcon A lenses.

Deposition Rates and Lens Care Influence on Galyfilcon A Silicone Hydrogel Lenses

PURPOSE

The purpose of this study is to investigate the frequency of deposition and impact of various multipurpose care regimens on a silicone hydrogel contact lens material (galyfilcon A; Acuvue Advance, Vistakon, Inc.).

METHODS

This was a two-phase, monadic, open-label, daily-wear clinical study. The analyses from Phase I were aimed at determining total lens front surface area deposition after two 2-week periods of galyfilcon A lens wear. Deposition was graded clinically using a slit-lamp biomicroscope from grade 0 (0% surface area) to grade 4 (>25% surface area). Secondary outcomes included visual acuity and self-reported overall comfort, end-of-day comfort, and perceived vision. Phase II determined the impact of various multipurpose solutions with and without a rub step on "heavy depositors" (grade 3 or 4) from a single phase I site. There were four arms associated with phase II, and front surface deposition was again the primary outcome with the same secondary outcomes as that mentioned previously.

RESULTS

In phase I, after the initial 2-week wear period, 9.4% of subjects exhibited grades 3 and 4 deposition. There were no differences in visual acuity, comfort, end-of-day comfort, and self-reported perceived vision when comparing "depositors" and "nondepositors." Twenty-seven "heavy depositors" from phase I completed phase II. After using Complete MoisturePlus (with a digital rub), no patients (0%) had clinically significant (grades 3 or 4) deposition, whereas for comparison, 33% of patients (the "heavy depositors") from phase I had clinically significant deposition without a digital rub (p=0.003). Similarly, 3.7% of patients had grade 3 or 4 deposition after using Opti-Free Express (with a digital rub) (p=0.01) and AOSEPT with a Miraflow-based rub (p=0.01) compared with the 33% of patients using Complete MoisturePlus without a digital rub. There were no differences in visual acuity or self-reported outcomes when stratified by lens care system in phase II.

CONCLUSIONS

Less than 10% of subjects exhibit clinically significant levels of deposition with galyfilcon A lenses when cleaned with Complete MoisturePlus (no-rub) multipurpose solution, and this was shown to not interfere with lens performance. The addition of a rub-and-rinse step to the care of galyfilcon lenses significantly reduces this deposition rate.

Objective and Subjective Responses in Patients Refitted to Daily-Wear Silicone Hydrogel Contact Lenses

PURPOSE

Silicone hydrogel (SiH) lenses offer many physiological advantages for daily wear (DW) in addition to the continuous-wear modality for which they were originally developed. The purpose of this study was to investigate the clinical performance and physiological responses in a group of successful long-term wearers of conventional hydrogel lenses when refitted with DW SiH contact lenses.

METHODS

Eighty-seven successful soft lens wearers (8.4+/-4.7 years of prior lens wear) participated in this study. Bulbar and limbal hyperemia were subjectively graded and digitally photographed for subsequent masked objective evaluation. Subjective symptoms were scored using visual analog scales. In addition, refractive error, corneal curvature, and corneal thickness were measured. All subjects were refitted with Focus Night & Day (lotrafilcon A) SiH lenses; however, to reduce the potential for bias, they were informed that they were being randomly assigned to wear either low oxygen permeability (Dk) lenses or high Dk SiH lenses and were "masked" as to their lens assignment. Subjects returned after 1 week, 1 month, and 2 months of DW, at which time all gradings, photographs, and measurements were repeated. End-of-day subjective symptoms were also graded periodically during the study.

RESULTS

Ninety-three percent of subjects were successfully refitted. Both objective and subjective evaluations showed that bulbar and limbal hyperemia decreased significantly in all quadrants during the study (p<0.001), particularly for those subjects with greater baseline hyperemia (p<0.001). Subjects reported a concurrent reduction in end-of-day dryness and improved end-of-day comfort compared with their habitual lenses (p<0.001). No significant changes in refractive error, tarsal papillary response, corneal curvature, or corneal thickness were found during the study.

CONCLUSIONS

Hyperemia in contact lens wearers may be attributed to a number of factors, including hypoxia. Refitting existing low Dk lens wearers with SiH lenses on a DW basis can result in a decrease in hyperemia, which may be significant for some subjects and also results in improvements in symptoms of dryness and discomfort.

Fusarium endophthalmitis following keratitis associated with contact lenses

A recent outbreak of fungal keratitis associated with contact lens use has been reported. During the past 4 months, a total of 36 patients with Fusarium keratitis have presented to one medical center. Two cases of Fusarium endophthalmitis resulting from this series of fungal keratitis associated with soft contact lens wear are described.

Higher Order Aberrations Induced by Soft Contact Lenses in Normal Eyes with Myopia

PURPOSE

To evaluate and compare the wavefront characteristics of normal eyes with and without hydrogel soft contact lenses for correction of myopia.

METHODS

Higher order aberrations (HOA) of 30 eyes of 15 soft contact lens users who had no ocular diseases other than myopia were quantified with a Nidek Marco three dimensional Wave wavefront analyzer. Zernike's polynomial was used to describe the wavefront measurements. Root mean square (RMS) values of the total HOAs, total coma, total trefoil and total spherical aberrations were obtained in the same eyes with and without soft contact lenses. We used paired sample t-test to analyze the data.

RESULTS

Mean RMS values for all higher order aberration components with and without soft contact lenses were: total HOA 0.364 +/- 0.129 microm without lenses and 0.456 +/- 0.175 microm with lenses (P = 0.01), total coma 0.203 +/- 0.095 microm without lenses and 0.220 +/- 0.133 microm with lenses (P = 0.51), total trefoil 0.193 +/- 0.074 microm without lenses and 0.254 +/- 0.153 microm with lenses (P = 0.06), total spherical aberration 0.126 +/- 0.121 microm without lenses and 0.148 +/- 0.095 microm with lenses (P = 0.36).

CONCLUSIONS

Wavefront analysis showed soft contact lenses for myopia induced a significant increase in total HOA. Though total coma, trefoil and spherical aberrations were also higher with contact lenses they were not statistically significant when individually evaluated and compared to values without contact lenses.

Severe Pseudomonas aeruginosa keratitis shortly after initiation of corneal refractive therapy

PURPOSE

To report the development of severe ulcerative keratitis in an adolescent, shortly after initiating corneal refractive therapy.

METHODS

A teenager developed severe ulcerative keratitis shortly after being fitted with reverse-geometry contact lenses. The contact lenses were worn daily and only one night before the occurrence of severe ulcerative keratitis. Pseudomonas aeruginosa was identified as the causative organism.

RESULTS

The patient was treated with intensive, fortified antibiotics with gradual resolution of the corneal ulcer, leaving a permanent central stromal scar.

CONCLUSIONS

Corneal refractive therapy contact lenses can cause severe bacterial keratitis even after a short wearing time. Significant caution should be used before prescribing corneal refractive therapy lenses, and informed consent should include potential sight-threatening infectious keratitis.

Pseudomonas aeruginosa-induced inflammation in the rat extended-wear contact lens model

PURPOSE

To examine the early host response to Pseudomonas aeruginosa challenge in the extended contact lens-wearing rat model.

METHODS

Lewis rats were fitted with extended-wear lotrafilcon A hydrogel lenses in the left eye, and the right eye served as the control. Bacterial challenge was initiated in the experimental eye by fitting a bacteria-soaked contact lens and by topical delivery of the bacteria. On first detection of corneal opacity, slitlamp examination, histopathologic examination, viable bacteria counts, enzyme-linked immunosorbent assay, myeloperoxidase, Langerhans cell detection, and multiprobe ribonuclease protection assays were used to evaluate the early corneal response.

RESULTS

Analysis of bacterially challenged contact lens-wearing versus control rats showed Langerhans cells and polymorphonuclear neutrophils only in the experimentally challenged cornea. In addition, in the experimentally challenged cornea, ribonuclease protection and enzyme-linked immunosorbent analyses showed an upregulation of proinflammatory cytokines, including interleukins 1beta and 6, suggesting that with contact lens wear, these cytokines contribute to the early corneal response and, potentially, disease.

CONCLUSIONS

The contact lens-wearing rat model allows a unique analysis of the early effects of bacterial challenge in extended-wear contact lenses in the absence of corneal scarring, used in most rodent models. The rat model should be valuable to delineate further the effects of contact lens wear, including the testing of additional contact lens-related complications.

Staphylococcus aureus Ulcer Associated With Continuous Wear of Silicone Hydrogel Contact Lenses

PURPOSE

To report a case of culture-positive Staphylococcus aureus keratitis associated with continuous wear of lotrafilcon A lenses.

METHODS

The case report of a patient who developed microbial keratitis while wearing lotrafilcon A contact lenses is presented.

RESULTS

A 41-year-old white man had worn polymacon contact lenses successfully for at least 10 years. He habitually replaced the lenses every 1 to 2 years and frequently wore them continuously for up to 3 months. He was refitted with silicone hydrogel lenses and was advised to remove and replace the lenses monthly. Approximately 18 months later, he developed a midperipheral, culture-positive S. aureus ulcer in his right eye. He was treated with fortified cefazolin and gentamicin for 2 weeks, followed by ciprofloxacin for 2 weeks. The ulcer resolved completely. The patient's final visual acuity was 20/20 in the affected eye.

CONCLUSIONS

The increased oxygen permeability of silicone hydrogel contact lens materials may reduce the risk of hypoxic complications of continuous contact lens wear. As this case shows, however, even patients who have continuously worn lenses with very low oxygen permeability without incident can develop microbial keratitis when wearing silicone hydrogel lenses. Contact lens practitioners should inform patients of the potential risks of continuous wear and of factors that may increase those risks.

Biocompatibility of nanofilm-encapsulated silicone and silicone-hydrogel contact lenses

A material placed in or in contact with a biological system, that causes the minimum perturbation that can be tolerated by the host biological system, can be considered to be biocompatible. The major effects caused by a contact lens can be considered to be 1) the blocking of the natural supply of oxygen to the epithelium cells of the cornea, 2) interference with the normal evaporation of water from the tear fluid layer, and 3) hindrance of the normal functions of blinking for replenishing oxygen-saturated tear fluid and removing dead epithelium cells, which result from apoptosis. The encapsulation of a highly oxygen-permeable contact lens by a nanofilm with an imperturbable surface state minimizes all these terms. The encapsulated contact lens can be worn safely in extended wear.

Prolonging contact lens wear and making contact lens wear safer

PURPOSE

To summarize the present status of safety and efficacy of contact lens wear.

DESIGN

Literature review.

METHODS

Ovid Medline searches were performed on records from 1966 through 2005 using keywords: keratitis, contact lens complications, extended-wear contact lenses, and silicone-hydrogel contact lenses.

RESULTS

Patients desire comfort, clarity of vision, and prolonged contact lens wear when contact lenses are used to correct refractive error. Practitioners desire patient satisfaction but also require maintenance of the integrity of the eye and no complications that jeopardize vision or health of the eye. Improvements in the oxygen permeability of the contact lens materials, design of the contact lens and its surface, and solutions for the maintenance of the lens have reduced but not eliminated the risks of infection, inflammation, and conjunctival papillary reaction associated with contact lens wear. The lessons of past and recent history suggest that patient education and practitioner participation in the management of contact lens wear continue to be critical factors for patient satisfaction and safety in the extended wear of contact lenses.

CONCLUSIONS

The availability of highly oxygen permeable contact lenses has increased the tolerance and safety of extended contact lens wear, but patient instruction and education in proper use and care of lenses is required and caution is advised.

Are high-water-content contact lenses safe?

We examined the role of tear secretion on contact lens water content during selection. Tear secretion was estimated using Schirmer's tests. High-water-content contact lenses compromised the tear film more than low-water-content contact lenses, hence they should not be advised in low or marginal Schirmer's test cases.

Two Presentations of Contact Lens-Induced Papillary Conjunctivitis (CLPC) in Hydrogel Lens Wear: Local and General

PURPOSE

The purpose of this study was to confirm that two distinct clinical presentations of contact lens-induced papillary conjunctivitis (CLPC), local and general, occur in hydrogel lens wear.

METHODS

Retrospective analyses of 124 CLPC events were identified. The classification of CLPC was based on location and extent of papillae. CLPC was classified as local if papillae were present in one to two areas of the tarsal conjunctiva and general if papillae occurred in three or more areas. The CLPC events were compared with an asymptomatic control group in prospective clinical trials conducted from 1993 until 2003 at two clinical sites, Australia and India. Two hundred sixteen subjects from Australia and 914 subjects from India wore either high Dk silicone hydrogel or low Dk hydrogel lenses on a 6-night (6N) or 30-night extended-wear (EW) schedule. The physiological responses of the ocular surface, including tarsal conjunctiva redness and roughness, number of papillae present, lens fit and performance, and subjective patient symptoms, were measured during each visit at each site. These variables listed were compared between local CLPC groups and asymptomatic controls and general CLPC groups and asymptomatic controls.

RESULTS

Two types of CLPC in hydrogel lens wearers have been confirmed. Of the 124 CLPC events, there were 61 local and 63 general events. Local and general CLPC cases reported significantly greater frequency of symptoms compared with the asymptomatic controls, in particular itching, lens awareness, secretion, and blurred vision (p < 0.1).

CONCLUSIONS

The classification of CLPC into two types, local and general, in hydrogel lens wear was confirmed based on presentations at both sites. This distribution of papillae between local and general CLPC may indicate separate etiologies involved in the pathogenesis of the condition.

Incidence of corneal pigmented arc and factors associated with its appearance in orthokeratology*

PURPOSE

To determine the incidence of the corneal pigmented arc in orthokeratology (ortho-k) lens wearers over 12 months of lens wear and the factors associated with its appearance.

METHOD

Thirty-five ortho-k subjects were recruited; refractive and corneal changes after lens wear (single-lens protocol) were monitored over 12 months. The incidence of the pigmented arc after 3, 6 and 12 months of lens wear was determined.

RESULTS

The incidence of corneal pigmented arc was 17% (27%), 49% (49%) and 90% (93%) after 3, 6 and 12 months lens wear respectively in the left and right eyes. For subjects with arcs observed in the left eye within the first 6 months of lens wear, the mean +/- S.D. period of lens wear before initial detection of the arc was 14 +/- 7.4 weeks, and no correlation was found between this factor and the baseline spherical and cylindrical refractive errors (i.e. refractive sphere and cylinder, respectively), spherical equivalent refractive error (SERE), the target myopia reduction, the amount of refractive sphere (or SERE) reduction and changes in central and peripheral corneal curvatures after 6 months of lens wear. Baseline refractive sphere, baseline SERE, target, amount of myopia reduction, and change in central corneal curvature were significantly larger (p < 0.05) in those subjects with pigmented arcs after about 6 months of lens wear. The intensity of the observed pigmented arcs after about 6 months of lens wear was significantly related to the time when it was first observed (p = 0.003). Significant correlation was also found between the intensity of the arcs and the following parameters: baseline refractive sphere and SERE, target, change in central corneal curvature, and amount of myopia reduction (p < 0.006). After about 12 months of lens wear, the intensity of observed arcs was significantly related to the baseline refractive sphere, SERE and the target (p < 0.006).

CONCLUSION

The incidence of ortho-k-associated pigmented arc increases from 17% after 3 months of lens wear to over 90% after 12 months of lens wear. The intensity of the arc is related to the time when the arc first appeared. Both the incidence and the intensity of the arc are related to the period of lens wear, baseline refractive sphere, SERE and the target.

Microbial flora of tears of orthokeratology patients, and microbial contamination of contact lenses and contact lens accessories

PURPOSE

The purpose of this study is to determine if there are changes in the ocular flora of overnight orthokeratology (ortho-k) patients, and the levels of contamination of their lenses and lens accessories, and to correlate compliance with levels of contamination.

METHOD

Normal ocular flora of 41 subjects was determined twice before commencing ortho-k lens wear by culture of the lower conjunctiva. Further specimens were collected on six follow-up visits after beginning lens wear, as were samples from their lenses, cases, and suction holders. A questionnaire on lens care was administered after the fifth visit.

RESULTS

Three subjects provided conjunctival samples yielding Staphylococcus aureus on one occasion before lens wear, one being positive for this organism after beginning lens wear. Of 38 subjects yielding no growth or only normal eye flora before use, 28 remained free of ocular pathogens after beginning lens wear. Only four subjects had positive cultures on more than one occasion after lens wear. There was no significant difference in isolation levels of pathogens with lens wear (p = 0.423). Lens culture of 54% of subjects yielded no growth or normal flora only; lenses of 16 subjects yielded potential pathogens, including three subjects contaminated on more than one occasion. Lens isolates did not match the organisms transiently colonizing the eye. Lens case, the most frequently contaminated item, was associated with lens contamination (p < 0.001), the same organism being isolated from both items in 11 subjects. Lens suction holder was less frequently contaminated. Neither lens case nor suction holder contamination was associated with isolates from the eye. Reported good compliance correlated with lack of contamination in all but one subject. The most frequent breaches in the lens care protocol were failure to clean, disinfect, and replace the lens case.

CONCLUSION

Ocular flora was not altered by ortho-k lens wear over an extended period, and patients remained free of infection. Contaminants identified were generally of a transient nature. Most patients had significant contamination of at least one item, most frequently the lens case. Lens case isolates were significantly associated with those from the lens. The majority of patients reporting good compliance had low or no contamination of their lenses and accessories.

The size, location, and clinical severity of corneal infiltrative events associated with contact lens wear

PURPOSE

The purpose of this study is to determine the relationship between the size, location, and clinical severity of corneal infiltrative events (CIEs) associated with contact lens wear.

METHODS

We examined a series of contact lens wearers, presenting consecutively to a large hospital clinic, who had any form of CIE. The severity of the CIE was quantified using a clinical severity matrix based on scores attributed to each of 10 signs and symptoms. The infiltrate was accurately drawn on a schematic diagram of the ocular surface, and from this, we determined its size (i.e., largest dimension) and distance from the limbus. Cartograms were constructed to illustrate the size and location of the corneal infiltrates according to wearing modality and lens type.

RESULTS

Useable data pertaining to 111 patients were analyzed. A significant positive correlation was found between the distance of the infiltrate from the limbus versus clinical severity (p = 0.002), but not between the distance of the infiltrate from the limbus versus infiltrate size (p = 0.97). The cartograms revealed a tendency for infiltrates to occur in the superior cornea of patients wearing extended wear silicone hydrogel lenses (p = 0.0002) in the central cornea of patients wearing daily wear hydrogel daily disposable lenses (p = 0.007) and in the peripheral cornea of patients wearing daily wear hydrogel (excluding daily disposable) lenses (p = 0.0006).

CONCLUSIONS

These data statistically validate the previously held anecdotal notion that CIEs which occur in the peripheral cornea are less clinically severe than those which occur in the central cornea. Consideration of the distribution of CIEs may facilitate a better understanding of the etiology of these events and can serve to alert practitioners as to their likely clinical presentation.

Adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis to Silicone???Hydrogel Contact Lenses

PURPOSE

The purpose of this study is to compare the adhesion capabilities of the most important etiologic agents of microbial ocular infection to the recently available silicone-hydrogel lenses with those to a conventional hydrogel lens.

METHODS

In vitro static adhesion assays of Pseudomonas aeruginosa 10,145, Staphylococcus epidermidis 9142 (biofilm-positive), and 12,228 (biofilm-negative) to two extended-wear silicone-hydrogel lenses (balafilcon A and lotrafilcon A), a daily wear silicone-hydrogel lens (galyfilcon A) and a conventional hydrogel (etafilcon A) were performed. To interpret the adhesion results, lens surface relative hydrophobicity was assessed by water contact angle measurements.

RESULTS

P. aeruginosa and S. epidermidis 9142 exhibited greater adhesion capabilities to the extended wear silicone-hydrogel lenses than to the daily wear silicone- and conventional hydrogel lenses (p < 0.05). No statistical differences were found between the adhesion extent of these strains to galyfilcon A and etafilcon A. The biofilm negative strain of S. epidermidis adhered in larger extents to the silicone-hydrogel lenses than to the conventional hydrogel (p < 0.05), but in much lower amounts than the biofilm-positive strain. The water contact angle measurements revealed that the extended wear silicone-hydrogel lenses are hydrophobic, whereas the daily wear silicone- and conventional hydrogel lenses are hydrophilic.

CONCLUSIONS

As a result of their hydrophobicity, the extended wear silicone-hydrogel lenses (lotrafilcon A and balafilcon A) may carry higher risk of microbial contamination than both the hydrophilic daily wear silicone-hydrogel lens, galyfilcon A and the conventional hydrogel lens, etafilcon A.

Impact of Previous Extended and Daily Wear Schedules on Signs and Symptoms With High Dk Lotrafilcon A Lenses

PURPOSE

This study measured the impact of previous contact lens wearing schedule on the resolution of signs and contact lens-related symptoms among wearers of lotrafilcon A lenses.

METHODS

One hundred forty adapted low Dk daily wear (DW) and 140 adapted low Dk extended wear (EW) subjects were enrolled and examined for 1 year (overall study length is 3 years). All subjects wore lotrafilcon A lenses on a wearing schedule of up to 30 nights continuous wear with monthly replacement of lenses. Examinations were conducted at 1 week, 1, 6, and 12 months.

RESULTS

The former EW wearers presented at baseline with significantly higher conjunctival staining and epithelial microcysts (p < 0.05) and lower ocular surface symptoms of end of day dryness than the former DW wearers. There were no significant differences in other ocular signs at baseline for the former DW and EW wearers. After use of lotrafilcon A, clinical signs of limbal, conjunctival redness, and neovascularization were significantly better by the 1-week visit for both groups of wearers. Regardless of former wearing schedule, symptoms of dryness (during and at the end of the day) and photophobia were significantly better after 1 week of lotrafilcon A use. The frequency and severity of symptoms of dryness during the day improved significantly among former low Dk DW and EW wearers within 1 week as did severity of dryness during the day for the former DW wearers, in part as a result of their higher prevalence at baseline in the DW group. Subjects reported redness improved significantly by the 1-month visit.

CONCLUSIONS

Continuous wear of high Dk silicone hydrogel lenses resulted in an improvement in ocular redness and neovascularization and dryness symptoms among subjects in this trial, regardless of their previous low Dk lens-wearing schedule. All improvements in signs and symptoms were sustained through 12 months.

Comparative Clinical Performance of Rigid versus Soft Hyper Dk Contact Lenses Used for Continuous Wear

PURPOSE

The purpose of this study is to investigate the comparative clinical performance of two hyper Dk contact lenses: a silicone hydrogel lens (Focus Night & Day, Ciba Vision) and a rigid lens (Z-alpha, Menicon Co. Ltd.) when worn for up to 30 days of continuous wear (CW). The rigid lens was worn on an unplanned replacement basis, whereas the soft lens was replaced monthly.

METHODS

One hundred subjects were recruited. Fifty neophyte subjects were randomly assigned into one of the lens types (25 subjects per lens type). Twenty-five existing daily wear (DW) rigid lens users wore the rigid study lens and 25 existing DW soft lens users wore the soft study lens. Visual acuity, lens fit, keratometry, refraction, lens surface assessment, physiological response, and subjective response were investigated at baseline and after 1 week of DW and 24 hours, 1 week, and 1, 3, 6, 9, and 12 months of CW. Analysis compared lens type (rigid vs. soft) and subject group (experienced vs. neophyte).

RESULTS

Sixty-eight subjects completed the study. Visual acuity was similar for the two lens types and subject groups. Lens fit was judged to be adequate in all subjects. Corneal curvature of subjects in the rigid groups became flatter by 0.13 mm compared with 0.04 mm for subjects in the soft lens groups (F = 14.7, p = 0.0003); the refractive findings mirrored these corneal changes. The increasing rate of deposition on rigid lenses was consistent with the fact that these lenses were not replaced during the study. Conjunctival hyperemia and staining were similar for the two lens types but greater among experienced wearers at baseline (F = 13.8, p = 0.0005; F = 5.3, p = 0.02, respectively). Corneal staining was higher for the rigid lens wearers (F = 5.6, p = 0.02) but this was mainly the result of the initial higher scores in the rigid lens experienced group. The change in papillary conjunctivitis was greater for subjects in the soft lens groups than rigid lens groups (F = 4.6, p = 0.04). Comfort was initially lower for the rigid lens neophyte group (F = 4.2, p = 0.0001), but after the CW phase started, there were no differences between groups.

CONCLUSIONS

Notwithstanding subtle differences in physiological responses, continuous wear hyper Dk rigid and soft silicone-containing contact lenses can be successfully worn by both those with previous contact lens experience and those with no history of contact lens wear.

Adverse Events and Discontinuations With Rigid and Soft Hyper Dk Contact Lenses Used for Continuous Wear

PURPOSE

The purpose of this study was to assess the relative clinical success of hypertransmissible rigid and soft contact lenses in terms of the rates of adverse events and clinical discontinuations.

METHODS

One hundred subjects (50 experienced wearers and 50 neophytes) were fitted with either the Z-alpha lens (Menicon) or the Focus Night & Day lens (CIBA Vision), which were worn on a 30-day continuous wear basis. The rates of adverse events and clinical discontinuations were monitored over 12 months.

RESULTS

There were 20 adverse events that were categorized as being serious or significant--four with rigid lenses and 16 with soft lenses (p = 0.003). There was no significant difference between the experienced (10) and the neophyte (10) groups (p = 1.00). There were 23 clinical discontinuations--13 with rigid lenses and 10 with soft lenses (p = 0.46). Fewer experienced wearers (five) discontinued than neophytes (18) (p = 0.002).

CONCLUSIONS

Practitioners should anticipate fewer adverse events with rigid versus soft lenses prescribed for continuous wear. Experienced wearers are less likely to discontinue compared with neophytes.

Incidence of keratitis of varying severity among contact lens wearers

AIM

To determine the incidence of non-severe keratitis (NSK) and severe keratitis (SK) among wearers of current generation contact lenses.

METHODS

A 12 month, prospective, hospital based epidemiological study was conducted by examining all contact lens wearers presenting with a corneal infiltrate/ulcer to a hospital centre in Manchester. A clinical severity matrix was used to differentiate between NSK and SK, based on the severity of signs and symptoms. The size of the hospital catchment population and the wearing modalities (daily wear (DW) or extended wear (EW)) and lens types being used were estimated from relevant demographic and market data.

RESULTS

During the survey period, 80 and 38 patients presented with NSK and SK, respectively. The annual incidences (cases per 10,000 wearers) for each wearing modality and lens type were: DW rigid--NSK 5.7, SK 2.9; DW hydrogel daily disposable--NSK 9.1, SK 4.9; DW hydrogel (excluding daily disposable)--NSK 14.1, SK 6.4; DW silicone hydrogel--NSK 55.9, SK 0.0; EW rigid--NSK 0.0, SK 0.0; EW hydrogel--NSK 48.2, SK 96.4; EW silicone hydrogel--NSK 98.8, SK 19.8. The difference in SK between EW hydrogel and EW silicone hydrogel was significant (p = 0.04).

CONCLUSIONS

A clinical severity matrix has considerable utility in assessing contact lens related keratitis. There is a significantly higher incidence of SK in wearers who sleep in contact lenses compared with those who only use lenses during the waking hours. Those who choose to sleep in lenses should be advised to wear silicone hydrogel lenses, which carry a five times decreased risk of SK for extended wear compared with hydrogel lenses.

Continuous wear silicone hydrogel contact lenses and microbial keratitis

Like other lens types, the new generation of silicone hydrogel contact lenses can be associated with a spectrum of ocular complications. Most tend to be very minor, but serious and sight-threatening complications can occur. We present four such cases with microbial keratitis following extended wear of these lenses. Cultures were positive for Pseudomonas aeruginosa in three cases and all three of these suffered lasting visual impairment. We describe our findings and discuss possible risk factors.

Therapeutic Use of Focus?? Night & Day??? Contact Lenses

PURPOSE

To evaluate the safety and efficacy of Focus Night & Day extended-wear contact lenses when used for therapeutic purposes.

METHODS

Fifty eyes of 50 consecutive patients presenting at the Ankara University Medical Center, Cornea and Contact Lens Service, and requiring bandage contact lens use for ocular surface disorders, were enrolled. All patients were fitted with Focus Night & Day contact lenses and were followed in regard to patient satisfaction, contact lens fit and performance, and success of treatment.

RESULTS

Twenty-four patients (48%) were male, and 26 (52%) were female. Average age at the time of presentation was 46.9 +/- 21.6 years (range 1.5 to 88 years). Therapeutic contact lens indications included Fuchs' dystrophy (2 eyes), toxic epitheliopathy (1 eye), filamentous keratopathy (2 eyes), corneal perforation (2 eyes), corneal stromal melting (2 eyes), recurrent corneal erosion (4 eyes), chemical or traumatic epithelial defect (3 eyes), epithelial irregularity (1 eye), persistent epithelial defect (4 eyes), lamellar laceration (5 eyes), graft insufficiency (2 eyes), pseudophakic bullous keratopathy (7 eyes), aphakic bullous keratopathy (4 eyes), disciform keratitis (1 eye), postkeratectomy (4 eyes), and post-amniotic membrane transplantation or post-limbal autograft transplantation (6 eyes). Mean duration of continuous contact lens wear was 2.4 +/- 3.0 months (range 3 days to 12 months). At the end of the follow-up period, the mean change in visual acuity was a gain of 1.8 +/- 2.8 logMAR units (0-9 Snellen lines). No sight-threatening complications related to contact lens wear were encountered. A culture-negative sterile corneal infiltrate developed in one patient and was treated with cessation of lens wear and subsequent topical antibiotic and steroids.

CONCLUSION

Focus Night & Day contact lenses are safe and effective when used for therapeutic purposes. Infrequent replacement of these lenses seems to be especially advantageous in patients for whom frequent lens insertion and removal may be associated with epithelial trauma, pain, and a potential increase in infection risk. Infrequent replacement of these lenses also decreased the office time and the cost of treatment without an increase in hypoxia-related complications.

Bilateral corneal neovascularization and opacification associated with unmonitored contact lens wear

PURPOSE

To report a case of severe bilateral deep stromal neovascularization and opacification associated with unmonitored contact lens wear.

DESIGN

Observational case report.

METHODS

A 46-year-old woman who had been using hydrogel contact lenses bought on the Internet without a prescription for 5 years was found to have dense, bilateral corneal opacities with deep stromal neovascularization.

RESULTS

The patient's contact lenses were found to be tight-fitting. Medical history and serological studies were negative for infectious or rheumatologic causes of interstitial keratitis.

CONCLUSIONS

The deep stromal neovascularization and the associated corneal opacification are most likely related to the unmonitored contact lens use and the lack of routine eye examinations. We believe it is critical that all contact lens wearers receive professional eye care on a regular basis regardless of where they obtain their contact lens supplies.