Acanthamoeba keratitis in South India: a longitudinal analysis of epidemics

PURPOSE

In light of the increased incidence of contact lens associated Acanthamoeba keratitis in recent years, this study analyzed longitudinal trends of its incidence among predominantly non-contact lens wearers in a high-volume referral center in South India.

METHODS

A retrospective analysis of microbiology laboratory records at the Aravind Eye Hospital from 1988-2009 was performed. The Maximum Excess Events Test (MEET) was used to identify epidemics of Acanthamoeba keratitis.

RESULTS

There were a total of 38,529 unique cases of infectious keratitis evaluated over this time period, of which 372 were culture-positive for Acanthamoeba. Only three cases (0.9%) of Acanthamoeba keratitis occurred among contact lens wearers. MEET identified unique Acanthamoeba keratitis epidemics in 1993 and 2002.

CONCLUSION

Discrete epidemics of Acanthamoeba keratitis occurred among a rural, non-contact lens wearing, population in South India in 1993 and 2002.

Pseudomonas aeruginosa keratitis: outcomes and response to corticosteroid treatment

PURPOSE

To compare the clinical course and effect of adjunctive corticosteroid therapy in Pseudomonas aeruginosa with those of all other strains of bacterial keratitis.

METHODS

Subanalyses were performed on data collected in the Steroids for Corneal Ulcers Trial (SCUT), a large randomized controlled trial in which patients were treated with moxifloxacin and were randomly assigned to 1 of 2 adjunctive treatment arms: corticosteroid or placebo (4 times a day with subsequent reduction). Multivariate analysis was used to determine the effect of predictors, organism, and treatment on outcomes, 3-month best-spectacle-corrected visual acuity (BSCVA), and infiltrate/scar size. The incidence of adverse events over a 3-month follow-up period was compared using Fisher's exact test.

RESULTS

SCUT enrolled 500 patients. One hundred ten patients had P. aeruginosa ulcers; 99 of 110 (90%) enrolled patients returned for follow-up at 3 months. Patients with P. aeruginosa ulcers had significantly worse visual acuities than patients with other bacterial ulcers (P = 0.001) but showed significantly more improvement in 3-month BSCVA than those with other bacterial ulcers, adjusting for baseline characteristics (-0.14 logMAR; 95% confidence interval, -0.23 to -0.04; P = 0.004). There was no significant difference in adverse events between P. aeruginosa and other bacterial ulcers. There were no significant differences in BSCVA (P = 0.69), infiltrate/scar size (P = 0.17), and incidence of adverse events between patients with P. aeruginosa ulcers treated with adjunctive corticosteroids and patients given placebo.

CONCLUSIONS

Although P. aeruginosa corneal ulcers have a more severe presentation, they appear to respond better to treatment than other bacterial ulcers. The authors did not find a significant benefit with corticosteroid treatment, but they also did not find any increase in adverse events. (ClinicalTrials.gov number, NCT00324168.).

Corticosteroids for bacterial keratitis: the Steroids for Corneal Ulcers Trial (SCUT)

OBJECTIVE

To determine whether there is a benefit in clinical outcomes with the use of topical corticosteroids as adjunctive therapy in the treatment of bacterial corneal ulcers.

METHODS

Randomized, placebo-controlled, double-masked, multicenter clinical trial comparing prednisolone sodium phosphate, 1.0%, to placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and received topical moxifloxacin for at least 48 hours before randomization.

MAIN OUTCOME MEASURES

The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months from enrollment. Secondary outcomes included infiltrate/scar size, reepithelialization, and corneal perforation.

RESULTS

Between September 1, 2006, and February 22, 2010, 1769 patients were screened for the trial and 500 patients were enrolled. No significant difference was observed in the 3-month BSCVA (-0.009 logarithm of the minimum angle of resolution [logMAR]; 95% CI, -0.085 to 0.068; P = .82), infiltrate/scar size (P = .40), time to reepithelialization (P = .44), or corneal perforation (P > .99). A significant effect of corticosteroids was observed in subgroups of baseline BSCVA (P = .03) and ulcer location (P = .04). At 3 months, patients with vision of counting fingers or worse at baseline had 0.17 logMAR better visual acuity with corticosteroids (95% CI, -0.31 to -0.02; P = .03) compared with placebo, and patients with ulcers that were completely central at baseline had 0.20 logMAR better visual acuity with corticosteroids (-0.37 to -0.04; P = .02).

CONCLUSIONS

We found no overall difference in 3-month BSCVA and no safety concerns with adjunctive corticosteroid therapy for bacterial corneal ulcers.

APPLICATION TO CLINICAL PRACTICE

Adjunctive topical corticosteroid use does not improve 3-month vision in patients with bacterial corneal ulcers.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00324168.

The steroids for corneal ulcers trial: study design and baseline characteristics

OBJECTIVES

To provide comprehensive trial methods and baseline data for the Steroids for Corneal Ulcers Trial and to present epidemiological characteristics such as risk factors, causative organisms, and ulcer severity.

METHODS

Baseline data from a 1:1 randomized, placebo-controlled, double-masked clinical trial comparing prednisolone phosphate, 1%, with placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and had been taking moxifloxacin for 48 hours. The primary outcome for the trial is best spectacle-corrected visual acuity at 3 months from enrollment. This report provides comprehensive baseline data, including best spectacle-corrected visual acuity, infiltrate size, microbiological results, and patient demographics, for patients enrolled in the trial.

RESULTS

Of 500 patients enrolled, 97% were in India. Two hundred twenty patients (44%) were agricultural workers. Median baseline visual acuity was 0.84 logMAR (Snellen, 20/125) (interquartile range, 0.36-1.7; Snellen, 20/50 to counting fingers). Baseline visual acuity was not significantly different between the United States and India. Ulcers in India had larger infiltrate/scar sizes (P = .04) and deeper infiltrates (P = .04) and were more likely to be localized centrally (P = .002) than ulcers enrolled in the United States. Gram-positive bacteria were the most common organisms isolated from the ulcers (n = 366, 72%).

CONCLUSIONS

The Steroids for Corneal Ulcers Trial will compare the use of a topical corticosteroid with placebo as adjunctive therapy for bacterial corneal ulcers. Patients enrolled in this trial had diverse ulcer severity and on average significantly reduced visual acuity at presentation.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00324168.

Nepafenac-assisted mydriasis in a rabbit model

PURPOSE

To compare the effectiveness of nepafenac 0.10% in achieving and maintaining pupil dilation with the effectiveness of flurbiprofen 0.03% and a placebo in a rabbit model.

SETTING

Department of Ophthalmology, University of California, San Francisco, California, USA.

DESIGN

Laboratory study.

METHODS

Adult pigmented rabbits were randomized to 3 equal-sized groups: placebo, flurbiprofen, and nepafenac. Cataract surgery was performed in randomized order by a surgeon who was masked to group assignment. The treatment or placebo was administered starting 1 day before surgery. Phenylephrine 10.0% was administered starting 30 minutes before surgery. Phacoemulsification was performed in standard fashion. Pupil measurements were recorded before and after surgery. A linear mixed model with a random effect for the rabbits and a fixed effect for the treatment groups was used to compare mean pupil diameters between groups.

RESULTS

Baseline pupil measurements were similar between the placebo, flurbiprofen, and nepafenac groups. Preoperative pupil dilation was statistically significantly greater in the nepafenac group (mean 11.5 mm ± 0.5 [SD]) than in the placebo group (mean 10.2 ± 1.1 mm) and the flurbiprofen group (mean 9.9 ± 1.1 mm) (P<.005 and P<.001, respectively). The greater dilation was maintained at the end of surgery, at which time the nepafenac group had statistically significantly larger pupils (mean 9.4 ± 1.2 mm) than the placebo group (mean 7.9 ± 0.6 mm) and the flurbiprofen group (mean 8.5 ± 0.9 mm) (P<.001 and P<.05, respectively).

CONCLUSION

Nepafenac was more effective than a placebo and flurbiprofen in achieving maximum preoperative and postoperative pupil mydriasis in rabbits.

Comparison of natamycin and voriconazole for the treatment of fungal keratitis

OBJECTIVE

To conduct a therapeutic exploratory clinical trial comparing clinical outcomes of treatment with topical natamycin vs topical voriconazole for fungal keratitis.

METHODS

The multicenter, double-masked, clinical trial included 120 patients with fungal keratitis at Aravind Eye Hospital in India who were randomized to receive either topical natamycin or topical voriconazole and either had repeated scraping of the epithelium or not.

MAIN OUTCOME MEASURES

The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months. Other outcomes included scar size, perforations, and a subanalysis of BSCVA at 3 months in patients with an enrollment visual acuity of 20/40 to 20/400.

RESULTS

Compared with those who received natamycin, voriconazole-treated patients had an approximately 1-line improvement in BSCVA at 3 months after adjusting for scraping in a multivariate regression model but the difference was not statistically significant (P = .29). Scar size at 3 months was slightly greater with voriconazole after adjusting for scraping (P = .48). Corneal perforations in the voriconazole group (10 of 60 patients) were not significantly different than in the natamycin-treated group (9 of 60 patients) (P >.99). Scraping was associated with worse BSCVA at 3 months after adjusting for drug (P = .06). Patients with baseline BSCVA of 20/40 to 20/400 showed a trend toward a 2-line improvement in visual acuity with voriconazole (P = .07).

CONCLUSIONS

Overall, there were no significant differences in visual acuity, scar size, and perforations between voriconazole- and natamycin-treated patients. There was a trend toward scraping being associated with worse outcomes. Application to Clinical Practice The benefit seen with voriconazole in the subgroup of patients with baseline visual acuity of 20/40 to 20/400 needs to be validated in a confirmatory clinical trial. Trial Registration clinicaltrials.gov Identifier: NCT00557362.

Activity of antibiotics against Fusarium and Aspergillus

BACKGROUND/AIMS

To study the susceptibility of Fusarium and Aspergillus isolated from keratitis to amoxicillin, cefazolin, chloramphenicol, moxifloxacin, tobramycin and benzalkonium chloride (BAK).

METHODS

10 isolates of Fusarium and 10 isolates of Aspergillus from cases of fungal keratitis at Aravind Eye Hospital in South India were tested using microbroth dilution for susceptibility to amoxicillin, cefazolin, chloramphenicol, moxifloxacin, tobramycin and BAK. The minimum inhibitory concentration (MIC) median and 90th percentile were determined.

RESULTS

BAK had the lowest MIC for both Fusarium and Aspergillus. Chloramphenicol had activity against both Fusarium and Aspergillus, while moxifloxacin and tobramycin had activity against Fusarium but not Aspergillus.

CONCLUSIONS

The susceptibility of Fusarium to tobramycin, moxifloxacin, chloramphenicol and BAK and of Aspergillus to chloramphenicol and BAK may explain anecdotal reports of fungal ulcers that improved with antibiotic treatment alone. While some of the MICs of antibiotics and BAK are lower than the typically prescribed concentrations, they are not in the range of antifungal agents such as voriconazole, natamycin and amphotericin B. Antibiotics may, however, have a modest effect on Fusarium and Aspergillus when used as initial treatment prior to identification of the pathological organism.

Evaluation of the Relationship Between Ablation Diameter, Pupil Size, and Visual Function With Vision-Specific Quality-of-Life Measures After Laser In Situ Keratomileusis

OBJECTIVE

To evaluate the relationship between ablation diameter, pupil size, and visual function as measured by a vision-specific quality-of-life instrument after undergoing laser in situ keratomileusis.

METHODS

Of 300 patients eligible for this study, 97 (32.3%) responded to a mailed study questionnaire, the National Eye Institute Refractive Error Quality of Life (RQL) Instrument. The RQL Instrument was administered in all 97 patients after laser in situ keratomileusis. Spearman correlation coefficients were calculated for the association between RQL subscale scores and characteristics including pupil diameter and uncorrected visual acuity.

RESULTS

Positive correlations between larger mesopic and scotopic pupil diameter and higher RQL satisfaction scores (0.12 and 0.19, respectively) were not statistically significant at the P=.05 level. As uncorrected visual acuity in the better eye improved, patients reported significantly less worry (-0.22; P=.03), more satisfaction (-0.25; P=.01), clearer vision (-0.25; P=.01), and better far vision (-0.24; P=.02).

CONCLUSION

Larger pupil diameter is not significantly associated with postoperative satisfaction and visual function as measured with the RQL. Rather, postoperative uncorrected visual acuity is confirmed as a strong predictor of patient satisfaction after refractive surgery.

Antimicrobial susceptibility of Fusarium, Aspergillus, and other filamentous fungi isolated from keratitis

OBJECTIVE

To characterize the susceptibility of filamentous fungi isolated from keratitis to amphotericin B, natamycin, caspofungin acetate, itraconazole, voriconazole, and posaconazole.

METHODS

Ninety isolates from fungal keratitis cases at Aravind Eye Hospital in South India were tested using macrobroth dilution for susceptibility to amphotericin B, natamycin, caspofungin, itraconazole, voriconazole, and posaconazole. The minimum inhibitory concentration (MIC) median and 90th percentile were determined.

RESULTS

The 90 isolates included 41 Aspergillus species, 38 Fusarium species, and 11 others. The triazoles and caspofungin had the lowest MICs against Aspergillus species; voriconazole, amphotericin B, and posaconazole had the lowest MICs against Fusarium species, and none of the Fusarium species were inhibited by itraconazole or caspofungin. Amphotericin B had significantly lower MICs compared with natamycin, but after correcting for the typical prescription dose, natamycin was superior.

CONCLUSION

No single agent was universally most effective, but voriconazole and other triazoles demonstrated the broadest spectrum. Itraconazole and caspofungin were not effective against Fusarium species.

CLINICAL RELEVANCE

Fungal ulcers are commonly treated empirically; drugs are typically selected without regard to susceptibility data. The nonocular infectious disease literature suggests modern fungal susceptibility methods are clinically relevant, but ocular studies are limited. Our results suggest antifungal therapy might be tailored to individual organisms.

Inter- and Intraobserver Reliability of Pupil Diameter Measurement During 24 Hours Using the Colvard Pupillometer

PURPOSE

To evaluate the inter- and intraobserver agreement of pupil size diameter measurements determined using the Colvard pupillometer.

METHODS

The eyes of 69 patients were examined (T1) using the Colvard pupillometer under mesopic and scotopic conditions by two examiners and repeated 1 hour (T2) and 24 hours (T3) later. The limits of agreement (mean difference between measurements +/- 2 standard deviations) were calculated for measurements between examiners (inter-examiner agreement) and between different time points measured by the same examiner (intra-examiner agreement).

RESULTS

At T1, there was a 99% and a 97% chance of two different examiners producing readings within 0.5 mm under mesopic and scotopic conditions, respectively. There was a 15% chance and a 9% chance of finding a pupil difference > 0.5 mm over 1 hour under mesopic and scotopic conditions, respectively. For mesopic and scotopic measurements taken 24 hours apart, there was a 31% chance and a 21% chance, respectively, of finding a difference > 0.5 mm by the same examiner.

CONCLUSIONS

This study showed high interobserver agreement under scotopic conditions, with 98% of measurements between two examiners falling within 0.5 mm, but substantial variability in pupil diameter measurements over 24 hours. These results suggest that serial office measurements may be necessary to establish the true range of pupil size.

Prophylactic Mitomycin C to Inhibit Corneal Haze After Photorefractive Keratectomy for Residual Myopia Following Radial Keratotomy

PURPOSE

To evaluate the efficacy and safety of mitomycin C (MMC) 0.02% in inhibiting haze formation after excimer laser photorefractive keratectomy (PRK) for residual myopia following radial keratotomy (RK).

METHODS

A prospective, nonrandomized, noncomparative interventional case series was conducted of 22 eyes (14 patients) with residual myopia after RK performed at a single institution. All eyes were treated with PRK and a single intraoperative topical application of MMC 0.02% solution for 2 minutes using a soaked cellulose sponge placed over the ablated area. Refraction, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and slit-lamp evidence of cotneal opacity (haze) were evaluated over 12 months.

RESULTS

Twelve months postoperatively, 3 eyes showed grade 1 haze, and 2 eyes showed grade 0.5 haze. Twelve months postoperatively, 2 (9%) eyes had UCVA > or = 20/20. No eye before and 17 (77%) eyes after treatment had UCVA > or = 20/40, and no eye before and 9 eyes (40.9%) after treatment had UCVA > or = 20/25. Best spectacle-corrected visual acuity was > or = 20/40 in all (100%) eyes and 21 (95%) eyes before and after treatment, respectively, and > or = 20/25 in 12 (54.5%) eyes before and after treatment. One (4.5%) eye lost 1 line of BSCVA. Mean spherical equivalent refraction achieved was -0.18 diopters (D) (range: -0.75 to +0.50 D) compared to -2.72 D (range: -1.50 to -4.00 D) before treatment. Twelve months after treatment, 19 (85.5%) eyes had a refractive outcome within +/- 0.50 D.

CONCLUSIONS

A single intraoperative application of MMC 0.02% for 2 minutes appears to be effective in preventing subepithelial haze after PRK for residual myopia in patients with undercorrection or regression following RK.

Synchrony dual-optic accommodating intraocular lens

PURPOSE

To describe a dual-optic accommodating intraocular lens (IOL) based on theoretical considerations.

SETTING

University and independent research group.

METHODS

Ray-tracing analysis using optical modeling software (ZEMAXTM, Focus Software Inc., Tucson, Ariz) in a theoretical model eye was used to analyze lens configurations to optimize the accommodative and magnification effects of axial lens displacement. Finite-element modelling using a commercially available PC-based software package (COSMOS DesignSTAR) was applied to design the biomechanical parameters of the inter-optic articulations and optics.

RESULTS

Ray-tracing analysis indicated that a dual-optic design with a high plus-powered front optic coupled to a minus posterior optic produced greater change in conjugation power of the eye compared to a single-optic intraocular lens and that magnification effects were unlikely to account for improved near vision. Finite-element modelling indicated that the 2 optics can be linked by spring-loaded haptics that allow anterior and posterior axial displacement of the front optic in response to changes in ciliary body tone and capsular tension.

CONCLUSION

A dual-optic design linked by spring haptics increases the accommodative effect of axial optic displacement with minimal magnification effect and has promise for improving the performance of accommodative intraocular lenses.

Synchrony dual-optic accommodating intraocular lens

PURPOSE

To evaluate the clinical outcomes of an accommodating dual-optic intraocular lens (IOL).

SETTING

Private practice and university centers.

METHODS

A prospective noncomparative case series with retrospective control comprised 21 patients (26 eyes) scheduled for small-incision extracapsular cataract extraction by phacoemulsification with implantation of the Synchrony dual-optic accommodating IOL (Visiogen) (accommodating IOL group) and 10 patients who had small-incision extracapsular phacoemulsification with implantation of a monofocal, single-optic IOL at least 6 months previously (control group). Patients were examined 1, 3, 6, and 12 months after surgery. Defocus curves in the accommodating IOL group were compared with those in the control group. The main outcome measures were postoperative distance uncorrected and best corrected visual acuity; near uncorrected, distance corrected, and near corrected visual acuity; and accommodative range based on defocus curves.

RESULTS

Twenty-four eyes were available at the 6-month follow-up visit. All eyes had best corrected distance visual acuity of 20/40 or better, and 19 eyes (79%) had an uncorrected distance visual acuity of 20/40 or better. Uncorrected near visual acuity was 20/40 or better in all eyes. With distance correction, 23 eyes (96%) had an acuity of 20/40 or better at near. Defocus curve analysis suggested a mean accommodative range of 3.22 diopters (D) +/- 0.88 (SD) (range 1.00 to 5.00 D) in the accommodating IOL group and 1.65 +/- 0.58 D in the control group (range 1.00 to 2.50 D) (P<.05).

CONCLUSION

The Synchrony dual-optic IOL shows promise as an option to provide accommodative function in pseudophakic patients.

Control of cell adhesion on poly(methyl methacrylate)

Keratoprostheses have been constructed from a wide variety of transparent materials, including poly(methyl methacrylate) (PMMA). However, the success of keratoprosthesis has been plagued by numerous shortcomings that include the weakening of the implant-host interface due to weak cell adhesion and opaque fibrous membrane formation over the inner surface of the implant due to fibroblast attachment. An effective solution requires a surface modification that would selectively allow enhanced cell attachment at the implant-host interface and reduced cell attachment over the interior surface of the implant. Here, we have developed a novel and simple peptide conjugation scheme to modify PMMA surfaces, which allowed for region-specific control of cell adhesion. This method uses di-amino-PEG, which can be grafted onto PMMA using hydrolysis or aminolysis method. PEG can resist cell adhesion and protein adsorption. The functionalization of grafted di-amino-PEG molecules with RGD peptide not only restored cell adhesion to the surfaces, but also enhanced cell attachment and spreading as compared to untreated PMMA surfaces. Long-term cell migration and micropatterning studies clearly indicated that PEG-PMMA surfaces with and without RGD conjugation can be used to differentiate cell adhesion and control cell attachment spatially on PMMA, which will have potential applications in the modification of keratoprostheses.

Optical principles, biomechanics, and initial clinical performance of a dual-optic accommodating intraocular lens (an American Ophthalmological Society thesis)

PURPOSE

To design and develop an accommodating intraocular lens (IOL) for endocapsular fixation with extended accommodative range that can be adapted to current standard extracapsular phacoemulsification technique.

METHODS

Ray tracing analysis and lens design; finite element modeling of biomechanical properties; cadaver eye implantation; initial clinical evaluation.

RESULTS

Ray tracing analysis indicated that a dual-optic design with a high plus-power front optic coupled to an optically compensatory minus posterior optic produced greater change in conjugation power of the eye compared to that produced by axial movement of a single-optic IOL, and that magnification effects were unlikely to account for improved near vision. Finite element modeling indicated that the two optics can be linked by spring-loaded haptics that allow anterior and posterior axial displacement of the front optic in response to changes in ciliary body tone and capsular tension. A dual-optic single-piece foldable silicone lens was constructed based on these principles. Subsequent initial clinical evaluation in 24 human eyes after phacoemulsification for cataract indicated mean 3.22 diopters of accommodation (range, 1 to 5 D) based on defocus curve measurement. Accommodative amplitude evaluation at 1- and 6-month follow-up in all eyes indicated that the accommodative range was maintained and that the lens was well tolerated.

CONCLUSIONS

A dual-optic design increases the accommodative effect of axial optic displacement, with minimal magnification effect. Initial clinical trials suggest that IOLs designed on this principle might provide true pseudophakic accommodation following cataract extraction and lens implantation.

Reliability of transport medium in the laboratory evaluation of corneal ulcers

PURPOSE

To compare the microbiological yield of corneal ulcer cultures established by direct inoculation of culture media vs indirect inoculation by means of transport medium (Amies without charcoal).

DESIGN

Single masked, prospective clinical trial.

METHODS

Scrapings were obtained for Gram and potassium hydroxide (KOH) stains from eyes with presumed infectious keratitis and cultured by direct plating onto standard media. Samples were also held in transport media (Amies without charcoal) at room temperature and then plated after 4 and 24 hours. Yields from direct plating vs cultures by means of transport media were compared.

RESULTS

Of 100 consecutive eyes examined with presumed infectious keratitis, Gram or KOH stain revealed a bacterial or fungal agent in 69 cases (69%). Of these, 26 were bacterial and 43 fungal. Twenty-two bacterial infections produced positive cultures by direct plating, and all produced the same organism with Amies medium after 4 and 24 hours, respectively. For 43 fungal infections identified by KOH stain, 29 (67%) yielded a positive result after 4 hours in Amies transport medium and 27 (63%) after 24 hours in Amies medium. A total of three cases (7%) that showed fungal infection on KOH stain but did not yield organisms by direct plating did so after inoculation with Amies transport medium. For all comparisons, there was no difference in recovery rates by means of transport medium compared with direct plating (McNemar exact P > .05).

CONCLUSIONS

In the clinical setting, Amies transport medium may be a useful alternative to direct inoculation onto blood agar for the laboratory evaluation of infectious keratitis.