Early-stage corneal toxicity secondary to high-dose systemic cytarabine: a case report.

BACKGROUND: High-dose systemic cytarabine chemotherapy may cause fine corneal opacities and refractile microcysts, which are densely distributed in the center of the cornea. Most previous case reports on microcysts have been those following complaints of subjective symptoms, and the findings at the initial stage of development and time-course changes are still unknown. This report aims to clarify the time-course changes of microcysts using slit-lamp photomicrographs. CASE PRESENTATION: A 35-year-old woman who was treated with high-dose systemic cytarabine therapy (3 courses of 2 g/m2 every 12 h for 5 days) for acute myeloid leukemia and presented with subjective symptoms, such as bilateral conjunctival injection, photophobia, and blurred vision, on the 7th day of treatment in both the first two courses. Anterior segment findings by slit-lamp microscopy revealed microcysts densely distributed in the central region of the corneal epithelium. In both courses, microcysts disappeared within 2-3 weeks upon prophylactic steroid instillation. In the 3rd course, daily ophthalmic examinations were conducted from the start of the treatment, and on the 5th day without subjective symptoms, the microcysts in the corneal epithelium appeared evenly and sparsely distributed throughout the cornea except for the corneal limbus. Thereafter, the microcysts accumulated towards the center of the cornea and disappeared gradually. The change from low-dose to full-strength steroid instillation immediately following the occurrence of microcysts in the 3rd course resulted in the peak finding being the mildest compared to that in the past two courses. CONCLUSIONS: Our case report revealed that microcysts appeared scattered throughout the cornea before the appearance of subjective symptoms and then accumulated in the center and disappeared. A detailed examination is necessary to detect early changes in microcyst development resulting in prompt and appropriate treatment.

Acute cataract by a high-intensity focused ultrasound procedure: a case report.

BACKGROUND: We report a case of acute onset of cataract after eyelid rejuvenation tightening with intense focused ultrasound (IFUS) treatment without using a protection device. CASE PRESENTATION: A 47-year-old female patient presented at the outpatient clinic with blurred vision in her left eye immediately after undergoing an eyelid tightening procedure, using IFUS, seven days prior. The patient had decreased vision in her left eye, caused by an acute cataract with several drop-like opacities and a rosette-like posterior subcapsular cataract. One month after her first visit, the patient's visual acuity in her left eye decreased to 20/630. A Swept-Source Anterior Segment optical coherence tomography confirmed that the posterior capsule was not ruptured. The patient underwent uneventful phacoemulsification cataract surgery with intraocular lens implantation, which resulted in full visual recovery. CONCLUSIONS: This case emphasized the need to evaluate possible ocular side effects, resulting from periocular IFUS without a protection device, including severe cataract requiring surgery.

Positive dysphotopsia after intrascleral intraocular lens fixation: a case report.

BACKGROUND: Positive dysphotopsia is a symptom caused by the reflection of incident light through the pupil at the inner surface of the intraocular lens (IOL) edge after cataract surgery and is perceived as an abnormal arcuate or radiating photopic image at night or indoors with a light source. Although positive dysphotopsia is one of the most important symptoms that affect patients after cataract surgery, it is still not well known even among ophthalmologists. Positive dysphotopsia as the cause of patient complaint following intraocular surgery other than cataract surgery has not been identified. CASE PRESENTATION: A 52-year-old man underwent IOL extraction and intrascleral IOL fixation for bilateral IOL subluxation at another hospital. The right eye had good subjective visibility, but the patient noticed symptoms of light sources appearing divided into multiple lights indoors after surgery in the left eye. Because the cause of the symptoms could not be identified, the patient visited our department. At the time of his first visit, the corrected visual acuity in both eyes was good, and ocular findings in eye position, motility, intraocular pressure, and fundus were within normal limits. The elongated holes of peripheral iridectomy (PI) created during previous intrascleral IOL fixation were observed to be approximately 2 mm in length on the nasal side in both eyes. The PI hole in the right eye was covered by the optics of the IOL, whereas the edge of the IOL overlapped the center of the PI hole in the left eye. Accordingly, we concluded that the abnormal photopic image in the left eye was caused by positive dysphotopsia, in which light passing through the PI hole was reflected by the edge of the IOL. We attempted surgical closure of the PI hole, resulting in the complete disappearance of positive dysphotopsia. CONCLUSIONS: A PI hole created during intrascleral IOL fixation may cause postoperative positive dysphotopsia depending on the position of the IOL edge. Thus, surgeons should be aware of the importance of the size and location of the PI hole when creating it during surgery.

Anterior Segment Optical Coherence Tomography Findings in Capsular Block Syndrome with Improvement in Myopia following Neodymium-Yttrium Aluminum Garnet Laser Treatment.

Introduction: Lacteocrumenasia is a relatively rare postoperative complication of cataract surgery. It is classified as a late-onset type of capsular block syndrome (CBS) and is often accompanied by myopia; however, its mechanism is not clearly understood. Case Presentation: We report a case of a 62-year-old male patient having CBS with myopia. The patient was treated with neodymium-yttrium aluminum garnet (Nd-YAG) laser posterior capsulotomy. We measured and compared the depth of the intraocular lens using anterior segment optical coherence tomography (AS-OCT) before and after laser treatment. Treatment resulted in refraction improvement of more than 1.0 diopters. The intraocular lens depth before and after Nd-YAG laser irradiation had very mild changes of less than 0.05 mm, which did not explain the refractive changes. Conclusion: Myopia in the early-onset type of CBS is caused by anterior deviation of the intraocular lens; however, the evaluation of this case using AS-OCT suggested that an abnormal intraocular lens position may not be involved in late-onset CBS.

Prediction of low-addition segmented refractive intraocular lens position and deviation using anterior-segment optical coherence tomography.

This study aimed to develop and analyze the accuracy of predictive formulae for postoperative anterior chamber depth, tilt, and decentration of low-added-segment refractive intraocular lenses. This single-center, retrospective, observational study included the right eyes of 96 patients (mean age: 72.43 ± 6.58 years), who underwent a cataract surgery with implantation of a low-added segmented refractive intraocular lens at the Medical University Hospital between July 2019 and January 2021, and were followed up for more than 1 month postoperatively. The participants were divided into an estimation group to create a prediction formula and a validation group to verify the accuracy of the formula. Anterior segment optical coherence tomography (CASIA 2, Tomey Corporation, Japan) and swept-source optical coherence tomography biometry (IOL Master 700, Carl Zeiss Meditec AG) were used to measure the anterior ocular components. A predictive formula was devised for postoperative anterior chamber depth, intraocular lens tilt, and intraocular lens decentration (p <0.01) in the estimation group. A significant positive correlation was observed between the estimated values calculated using the prediction formula and the measured values for postoperative anterior chamber depth (r = 0.792), amount of intraocular lens tilt (r = 0.610), direction of intraocular lens tilt (r = 0.668), and amount of intraocular lens decentration (r = 0.431) (p < 0.01) in the validation group. In conclusion, our findings reveal that predicting the position of the low-added segmented refractive intraocular lens enables the prognosis of postoperative refractive values with a greater accuracy in determining the intraocular lens adaptation.

Exacerbated Tourette syndrome diagnosed in adulthood after recurrent bilateral retinal detachment.

PURPOSE: To report a case of Tourette syndrome, exacerbated in adulthood, that was diagnosed after bilateral lens luxation and recurrent retinal detachment due to self-injury. METHODS: Case report. RESULTS: A 35-year-old man presented with a sudden abnormality in vision and bilateral lens luxation. The patient successfully underwent bilateral lens extraction and intrascleral intraocular lens fixation; however, vitreous hemorrhage and retinal detachment occurred in the left eye. The retinal detachment was caused by a giant retinal tear and retinal dialysis. Vitrectomy was performed. However, retinal detachment recurred with proliferative vitreoretinopathy. Retinal detachment subsequently occurred in the right eye. Self-injury to the eye was observed before surgical treatment. The patient was consequently diagnosed with Tourette syndrome. CONCLUSION: Tourette syndrome, which may be accompanied by self-injurious behavior, is a disorder that typically develops in childhood but rarely exacerbates during adulthood. A diagnosis of Tourette syndrome should be considered in cases of unexplained retinal detachment with traumatic features.

Orientation of the intermediate-vision zone of rotationally asymmetric multifocal intraocular lenses and photic phenomena.

PURPOSE: To evaluate the association between the orientation of the intermediate-vision zone and postoperative photic phenomena in eyes implanted with rotationally asymmetric multifocal intraocular lenses with + 1.5 diopters near addition. STUDY DESIGN: Retrospective comparative case series. METHODS: We performed the photic phenomena test (PPT) to quantitatively evaluate photic phenomena at 1-3 months after cataract surgery with Lentis Comfort LS-313 MF15 or Lentis Comfort Toric LS-313 MF15T insertion (Oculentis; Santen Pharmaceutical). In cases of bilateral surgeries, only the right eye was included in the analysis. We also conducted a questionnaire survey about the photic phenomena. RESULTS: The study included 96 eyes from 96 patients. The intermediate-vision zones of 44, 19, 19, and 14 eyes were fixed in the inferior, superior, nasal, and temporal directions, respectively. The measured PPT values for halo, glare, and starburst were equivalent in all the fixed directions. Eighty-four eyes (87.5%) perceived a triangle-shaped halo, and the direction of fixation for the intermediate-vision zone and the extension direction of this photic phenomenon were consistent in 94.0% of the eyes. Less than 10% of the patients responded "moderate" or "severe" for the triangle-shaped halo, glare, and starburst in fixed directions with low frequency in the questionnaire. CONCLUSION: No qualitative or quantitative difference was found in photic phenomena in eyes implanted with the LS-313 MF15 or the MF15T regardless of the fixation direction. Our study revealed that many patients were aware of a triangle-shaped halo extending in the direction of the intermediate-vision zone.

Use of 5-cyano-2,3-ditolyl-tetrazolium chloride staining as an indicator of biocidal activity in a rapid assay for anti-Acanthamoeba agents.

The usefulness of 5-cyano-2,3-ditolyl-tetrazolium chloride (CTC) staining to determine the respiratory activity of Acanthamoeba was evaluated in this study. Acanthamoeba trophozoites and cysts have a red fluorescence after staining with CTC. To determine the effectiveness of CTC staining as a CTC biocidal assay for Acanthamoeba, the trophozoites and cysts of Acanthamoeba castellanii (ATCC 5037) were treated with serial concentrations of disinfectant solutions, namely, polyhexamethylene biguanide (PHMB) and commercial soft contact lens (SCL) disinfectant solutions. The treated Acanthamoeba organisms were stained with CTC, and their respiratory activity was determined by the intensity of fluorescence in a fluorescence microplate reader. The survival rates of the same samples were determined by a culture-dependent biocidal assay using the Spearman-Karber method. Our results showed that the respiratory activities determined by the CTC biocidal assay and the survival rates determined by the culture-dependent biocidal assay for Acanthamoeba trophozoites and cysts decreased in a dose-dependent way after PHMB treatments, and the results were significantly correlated (r = 0.83 and P < 0.01 for trophozoites; r = 0.60 and P < 0.01 for cysts; Spearman rank correlation test). The respiratory activities in the trophozoites and cysts treated with SCL disinfectant solutions were significantly correlated with the survival rate (r = 0.70 and P < 0.01 for trophozoites; r = 0.64 and P < 0.01 for cysts; Spearman rank correlation test). The significant correlation of the results indicated that the CTC biocidal assay can be used as an alternative method to a culture-dependent biocidal assay. The CTC biocidal assay is a rapid and simple method to test the effectiveness of disinfectant solutions against Acanthamoeba trophozoites and cysts.

Assessment of real-time polymerase chain reaction detection of Acanthamoeba and prognosis determinants of Acanthamoeba keratitis.

OBJECTIVE: To evaluate the diagnostic value of real-time polymerase chain reaction (PCR) for detecting Acanthamoeba in eyes diagnosed with Acanthamoeba keratitis (AK) by conventional tests. In addition, to determine the preoperative prognosis-determining factors in eyes with AK. DESIGN: Retrospective, cross-sectional study. PARTICIPANTS: A total of 104 eyes of 103 patients who were diagnosed with AK or with bacterial or bacteria-associated keratitis (BK) by conventional tests. METHODS: Twenty-nine eyes with AK and 75 eyes with BK were evaluated for Acanthamoeba and bacterial DNA by real-time PCR. The Acanthamoeba copy numbers, bacterial load, and clinical parameters in the patients with AK were assessed for those significantly associated with poor outcome, that is, final visual acuity of <20/50 or requiring keratoplasty, by logistic regression analysis. MAIN OUTCOME MEASURES: Acanthamoeba DNA copy number, bacterial DNA copy number, and odds ratio (OR) for poor prognosis. RESULTS: The detection of amoebic DNA was 50 times more sensitive by real-time PCR than by conventional cyst counting. The Acanthamoeba copy numbers at the first visit (mean: 4.7×10(5)±3.2×10(5) copies) were significantly correlated with the AK stage, and both were significant risk factors for a poor outcome. The Acanthamoeba DNA copy numbers at the first visit and AK stage had a significantly high risk for poor outcome (OR of Acanthamoeba DNA copy per logarithm of copy numbers: 3.48, 95% confidence interval [CI], 1.04-111.63, P<0.05; OR of AK stage: 2.8 per stage increase, 95% CI, 1.07-7.30, P<0.05, after adjustment of age). In the AK cases with poor outcome, the amoebic DNA was not reduced by more than 90% after 1 month of treatment. The weak amoebic reduction was significantly associated with advanced AK stages or previous use of steroids. Bacterial 16S rDNA was detected in 53.6% of the eyes with AK, but it was not associated with any risk for refractoriness. CONCLUSIONS: Real-time PCR was effective in detecting and managing AK. The Acanthamoeba copy number and AK stage at the first visit were significantly associated with poor outcome. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Vision With Retrodots and Factors for Declining Visual Function.

Purpose: We investigated decline in the visual function of eyes with retrodots (RDs)-a subtype of cataract. Method: This study included 57 eyes with RD opacity only (mean age 72.3 ± 5.2 years) and 34 eyes with transparent lenses (mean age 71.4 ± 3.7 years). A physician diagnosed lens opacity. Using the Kanazawa Medical University Classification and Grading System, the eyes were classified into the RD-1 (37 eyes, RDs <25% of the 3-mm pupil area) and RD-2 (20 eyes, RDs ≥25% of the 3-mm pupil area) groups. Corrected distance visual acuity, contrast visual acuity, ocular refractive power, lens power, straylight, and backward light-scattering intensity and their relationship with visual function decline and optical characteristics of the eyeball were evaluated. Results: Corrected distance visual acuity was significantly lower in the RD eyes than in controls. Contrast visual acuity decreased significantly in the RD-2 eyes in all environments and in the RD-1 eyes in the evening (EVE) and EVE + glare. Straylight was significantly higher in the RD-2 eyes than in the controls and RD-1 eyes but not different between the RD-1 eyes and controls. The RD-2 eyes were significantly more myopic than the controls and RD-1 eyes. Conclusion: When the opacity of RD eyes is ≥25%, the visual acuity and contrast visual acuity decrease and straylight increases. Furthermore, myopia occurs as the refractive power of the lens increases. Moreover, visual function decline may be due to an increase in the straylight value, which is necessary for determining surgical indications.

Atezolizumab-induced bilateral anterior uveitis: A case report.

PURPOSE: To report a case of bilateral anterior uveitis undergoing atezolizumab treatment for advanced non-small cell lung cancer (NSCLC). OBSERVATIONS: A 64-year-old man was receiving atezolizumab for metastatic programmed cell death ligand 1 (PD-L1) positive NSCLC as first line therapy. Three weeks after first atezolizumab administration, he complained of blurry vision in both eyes and was referred to our clinic. At initial presentation, slit lamp examination revealed bilateral Descemet membrane folds, fine keratic precipitates, and anterior chamber cells 2+. Dilated fundus examination showed no abnormal findings. A complete laboratory evaluation ruled out infectious or autoimmune causes of the uveitis and he was diagnosed with uveitis caused by atezolizumab. Atezolizumab was suspended, administration of topical corticosteroid was initiated, and the anterior uveitis was resolved within one month. CONCLUSION AND IMPORTANCE: This is the first case report of bilateral anterior uveitis associated with atezolizumab and that PD-1 and PD-L1 inhibitors cause uveitis.

Quantitative assessment of photic phenomena in the presbyopia-correcting intraocular lens.

This was a prospective study to evaluate the feasibility of the photic phenomena test (PPT) for quantifying glare, halo, and starburst. We compared two presbyopia-correcting intraocular lenses (IOLs), the Symfony IOL and the PanOptix IOL, as well as the monofocal Clareon IOL in 111 IOL-implanted eyes of 111 patients who underwent the PPT 1 month postoperatively. The reproducibility of photic phenomena with the PPT was assessed in 39 multifocal IOL-implanted eyes of 20 patients and among the examiners. Patients with ocular diseases, except for refractive errors, were excluded. The mean values of the groups were evaluated. Bland-Altman plots were used to analyze statistical data (Easy R version 1.37; R Foundation for Statistical Computing, Vienna, Austria). The PPT reproducibility assessment revealed no fixed bias or regressive significance. Reproducibility was confirmed. The glare size did not differ significantly between the Symfony, PanOptix, and Clareon groups. The halo size was significantly larger in the Symfony group (p < 0.01) than in the PanOptix group. The halo intensity was significantly brighter in the PanOptix group (p < 0.01) than in the Symfony group. In contrast, no halos were perceived in the Clareon group. The starburst size or intensity did not differ significantly between the Symfony, PanOptix, and Clareon groups. We identified the photic phenomenon related to various IOLs.

Central scotoma after indocyanine green assisted fovea-sparing internal limiting membrane peeling.

PURPOSE: To report a case with myopic traction maculopathy (MTM) that underwent fovea-sparing internal limiting membrane (ILM) peeling and developed a central scotoma with a nasal visual field defect postoperatively. OBSERVATIONS: A 63-year-old man diagnosed with foveoschisis and a small outer lamellar macular hole underwent 25-gauge, 3-port pars plana vitrectomy and fovea-sparing ILM peeling using indocyanine green (ICG) staining. One year after the vitrectomy, optical coherence tomography (OCT) revealed a resolution of the macular retinoschisis and an intact ellipsoid zone at the fovea. However, macular edema was present over the area of the residual ILM, and the visual acuity had worsened to 20/200. Goldmann perimetry showed a central scotoma and a constriction of the nasal visual field. OCT angiography detected abnormal blood flow in the inner retina corresponding to the area of the residual foveal ILM. The multifocal electroretinograms were reduced in the central area. CONCLUSION: The findings suggest that functional abnormalities of the fovea induced by ICG toxicity may have been manifested by a central scotoma. Therefore, surgeons need to consider the toxic effects of dyes such as ICG.

Development of traumatic bilateral horseshoe-shaped macular tear without vitreous traction: Case report.

To report our findings in a case with bilateral horseshoe-shaped macular tears. Both eyes of a 68-year-old woman developed horseshoe-shaped macular tears in the absence of vitreous traction due to prior vitrectomy in one eye and a posterior vitreous detachment in the other eye. Vitrectomy with the inverted internal limiting membrane flap technique led to a successful closure of the macular tear bilaterally, and an improvement of her visual acuity in both eyes. The cause of horseshoe-shaped macular tear was most likely due to a retinal rupture from a blunt trauma.

Ocular penetration and efficacy of levofloxacin using different drug-delivery techniques for the prevention of endophthalmitis in rabbit eyes with posterior capsule rupture.

PURPOSE: To evaluate the effects of different drug-delivery techniques for levofloxacin (LVFX) in ocular penetration and the prevention of endophthalmitis using an aphakic rabbit model with posterior capsule rupture (PCR). METHODS: LVFX was administered to aphakic rabbit eyes with or without PCR using eye drops (EDs), subconjunctival injection (SCI), or intracameral (IC) injection. The concentration of the drug in the vitreous and aqueous humors was estimated at 2 h after injection. In another study, aphakic rabbit eyes with PCR were inoculated with Enterococcus faecalis, immediately followed by 0.5% LVFX ED, 0.5% moxifloxacin (MFLX) ED, LVFX IC (500 µg/0.1 mL), or IC saline. EDs were administered 0, 3, and 6 h after surgery. Changes on electroretinography (ERG) and intraocular bacterial growth were determined sequentially until 48 h after inoculation. RESULTS: The concentrations of LVFX at 2 h after IC were higher in the aqueous humor and the vitreous cavity of eyes with or without PCR, compared with EDs or SCI. Eyes treated with LVFX ED, MFLX ED, or IC saline showed a significantly greater reduction in b-wave amplitude on ERG at 48 h compared with eyes treated with LVFX IC. The number of bacteria recovered from the vitreous humor in eyes treated with IC LVFX at 48 h was significantly less than from eyes that received other treatments. CONCLUSION: The LVFX IC was effective at suppressing endophthalmitis caused by E. faecalis in eyes with a PCR.

Moxifloxacin as postoperative prophylaxis for Enterococcus faecalis-induced endophthalmitis after cataract surgery in aphakic rabbits.

PURPOSE: The development of endophthalmitis after cataract surgery often results in significant vision loss. Inhibition of bacterial proliferation in the anterior chamber using antibiotic eye drops is important to prevent endophthalmitis after cataract surgery. We aimed to determine the sensitivity of fluoroquinolones against Enterococcus faecalis ocular isolates and the efficacy of fluoroquinolones to prevent E. faecalis-induced endophthalmitis in aphakic rabbits. METHODS: The minimum inhibitory concentrations (MICs) of moxifloxacin (MFLX) and levofloxacin (LVFX) used in ophthalmic solutions for 13 E. faecalis isolates obtained from the conjunctival sac or endophthalmitis cases were determined. Eye drops containing MFLX (0.5%), LVFX (0.5%), or saline were administered to aphakic rabbits with endophthalmitis induced by E. faecalis. The eye drops were administered immediately after lensectomy and at 3 and 6 h after cataract surgery (early instillation group) or immediately after lensectomy and at 12 and 15 h after cataract surgery (delayed instillation group). Bacterial growth, electroretinography (ERG), and slit-lamp examination (SLE) were determined throughout the course of infection. RESULTS: In vitro susceptibility testing revealed that the MICs of MFLX for E. faecalis isolates were lower than those of LVFX. In the early ocular instillation groups, MFLX significantly improved SLE scores, ERG, and viable bacterial counts compared with LVFX and saline (all, P<0.05). There were no significant differences in any parameter between MFLX and saline in the delayed ocular instillation groups. CONCLUSIONS: Early ocular instillation of MFLX delays retinal damage compared with LVFX when used to treat E. faecalis-induced endophthalmitis after cataract surgery.

Effect of photodynamic therapy with methylene blue on Acanthamoeba in vitro.

PURPOSE: To evaluate the disinfectant effect of methylene blue (MB)-mediated photodynamic therapy (PDT) on a pathogenic strain of Acanthamoeba. METHODS: Acanthamoeba castellanii (ATCC 50370) used in this study were treated under one of four experimental conditions: light irradiation and incubation in MB (L+M+), light irradiation and incubation in physiologic solution (L+M-), incubation in MB only (L-M+), and incubation in physiologic solution (L-M-). M+ trophozoites were incubated in either 0.25 or 0.5 mM MB for 10 minutes. L+ organisms were irradiated for 30 minutes following incubation in solution. A halogen lamp (660 ± 10 nm) with a maximum output of 6 mW/cm(2) was used as the PDT light source. After treatment, antiacanthamoeba activity was evaluated by checking the respiratory activity of the amoeba with 5-cyano-2,3-tetrazolium chloride (CTC) staining. We also determined whether the effect of PDT with MB had been retained or augmented when it was performed in combination with conventional antiamoebic agents. RESULTS: MB-PDT suppressed the respiratory activity of trophozoites in an MB-concentration-dependent manner at total light doses of 10.8 J/cm(2). The respiratory activity of each group as a percentage of that of L-M- is as follows: L+M+ 11.6% (0.5 mM), 60.9% (0.25 mM); L-M+ 116.5% (0.5 mM), 105.5% (0.25 mM); L+M- 107.6%; and L-M- 106.3%. (L+M+ versus L-M- P < 0.05). MB-PDT had a synergistic effect when used in combination with polyhexamethylene biguanide (PHMB) or amphotericin B, but not with voriconazole. CONCLUSIONS: MB-PDT is effective against Acanthamoeba in vitro and has synergistic effects with PHMB and amphotericin B.

Efficacy of commercial soft contact lens disinfectant solutions against Acanthamoeba.

PURPOSE: To investigate the relative efficacy of Japanese commercial soft contact lens disinfectant solutions against Acanthamoeba trophozoites and cysts. MATERIALS AND METHODS: Eight types of multipurpose solution (MPS), two types of hydrogen peroxide solution, and one povidone-iodine solution were evaluated to determine their effect against Acanthamoeba trophozoites and cysts (ATCC 50514). Acanthamoeba cysts were cultured in encystment medium for either 1 or 2 weeks (1 and 2-week-old cysts). The trophozoites and cysts were treated with each disinfectant solution for 0, 2, 4, 8, or 24 h. After performing four tenfold serial dilutions of each test solution, dilutions were cultured for 10 days. The number of surviving organisms was calculated using the trimmed Spearman-Karber method. RESULTS: Among the MPS tested, only four were effective against trophozoites after treatment for 4 h, and none was effective against 2-week-old cysts. Hydrogen peroxide had a significant effect on trophozoites and 1-week-old cysts, but not on 2-week-old cysts. In contrast, povidone-iodine caused a 2.6 log reduction in 2-week-old cysts. CONCLUSIONS: MPS were found to have limited efficacy against trophozoites and no efficacy against 2-week-old cysts. Only povidone-iodine had any efficacy against 2-week-old cysts.