Publications by authors named "Chareenun Chirapapaisan"

21 Publications

  • Page 1 of 1

Characteristics of Corneal Subbasal Nerves in Different Age Groups: An in vivo Confocal Microscopic Analysis.

Clin Ophthalmol 2021 24;15:3563-3572. Epub 2021 Aug 24.

Research Division, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailanda.

Purpose: To determine the normative characteristics of corneal subbasal nerves in different age groups using laser scanning in vivo confocal microscopy (IVCM).

Patients And Methods: This descriptive observational study recruited healthy subjects (aged 20-60 years) from Siriraj Health-Screening Center. Excluded were individuals who had abnormal ocular symptoms, previous ocular surgery, a history of any diseases related to systemic and/or corneal neuropathy, or abnormal corneal sensitivity. Corneal IVCM (HRT3/Rostock Corneal Module) was performed at the central cornea to analyze the subbasal nerve plexus. The corneal nerve characteristics, comprising the number and density of nerves (main nerve trunks, branches, and total nerves) were analyzed using the NeuronJ program, and the corneal nerve tortuosity was graded. The correlations between the subbasal nerve density, tortuosity and age were then analyzed.

Results: Eighty subjects were enrolled, with twenty in each of four age groups (20-30, >30-40, >40-50, and >50-60 years). Overall, the mean number and density of main nerve trunks were 27.93±0.81/mm and 11.22±0.30 mm/mm, respectively. As of the nerve branches, the average number and density were 103.56±2.37/mm and 9.15±0.30 mm/mm, respectively. The total nerve density was 20.37±0.39 mm/mm. There were no significant differences between subbasal nerve parameters of the four age groups. It is noteworthy that 65% of the subjects aged over 40 years revealed high-grade nerve tortuosity.

Conclusion: The corneal subbasal nerve numbers and densities were not significantly different among a healthy population aged 20-60 years. However, there was a trend towards high tortuosity of the corneal nerve in people aged over 40 years.
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http://dx.doi.org/10.2147/OPTH.S324169DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8403225PMC
August 2021

Efficacy and outcome of simple limbal epithelial transplantation for limbal stem cell deficiency verified by epithelial phenotypes integrated with clinical evaluation.

Ocul Surf 2021 Jun 30;22:27-37. Epub 2021 Jun 30.

Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Purpose: To evaluate the efficacy and outcome of simple limbal epithelial transplantation (SLET) for limbal stem cell deficiency (LSCD) using epithelial phenotype detection integrated with clinical manifestation.

Methods: This prospective multicenter study included patients with LSCD who underwent autologous SLET (autoSLET) and living-related allogenic SLET (Lr-alloSLET). All patients were assessed by slit-lamp biomicroscopy, in vivo confocal microscopy (IVCM), and impression cytology with immunofluorescence staining (ICIF) before and after surgery. The criteria for success were the presence of a clinically non-conjunctivalized cornea and corneal epithelium detected by IVCM or ICIF. Otherwise, the case would be considered a failure. Visual improvement and risk factors for SLET failure were analyzed.

Results: A total of 28 eyes of 26 patients (11 autoSLET and 17 Lr-alloSLET) were included. The median age was 53 years (range, 35-63), and the follow-up time was 29.5 months (range, 17.5-39.8). The overall survival rate was 89.3% at 2 years and 75.6% at 3 years with no difference between autoSLET and Lr-alloSLET (p = 0.24). Seven eyes subsequently underwent penetrating keratoplasty. Immunohistochemistry analysis showed that all corneal buttons had corneal epithelium and limbal stem cell markers. Visual improvement was achieved in both SLET groups (p < 0.001). Failed SLET developed between 5 and 32 months postoperatively. However, absolute risk factors for SLET failure were unidentified.

Conclusion: The efficacy of autoSLET and Lr-alloSLET for LSCD was excellent. Limbal explants can regenerate and restore the corneal surface while maintaining the characteristics of limbal stem cells as shown by epithelial phenotype detection and immunohistochemistry integrated with clinical evaluation.
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http://dx.doi.org/10.1016/j.jtos.2021.06.012DOI Listing
June 2021

Successful Ocular Surface Reconstruction in Complete Ankyloblepharon With the Simple Oral Mucosal Epithelial Transplantation Technique: A Case Report.

Cornea 2021 Nov;40(11):1482-1486

Research Division, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Purpose: To report an outcome of a patient with complete ankyloblepharon successfully managed with simple oral mucosal epithelial transplantation (SOMET).

Methods: A 55-year-old woman presented with complete adhesion of both lids to the ocular surface as a complication from Stevens-Johnson syndrome. We performed 2-staged reconstructive surgeries: the first stage was to perform ankyloblepharon lysis and surface reconstruction with a mucosal graft on the palpebral area and an amniotic membrane on the bulbar area, and the second stage was to reconstruct the bulbar area with a transplantation of small pieces of oral mucosa (SOMET technique). Postoperatively, the patient was evaluated for ocular surface stability, recurrent symblepharon, in vivo confocal microscopy, and impression cytology with immunofluorescence staining.

Results: Complete epithelialization of cornea-like epithelium was observed within 6 weeks after SOMET was performed. The ocular surface was stable over 1 year. Both fornices remained deep. In vivo confocal microscopy showed cornea-like epithelium mixed with conjunctival epithelium, as confirmed with immunofluorescence staining, which revealed cytokeratin 3, cytokeratin 7, and cytokeratin 12 positivity.

Conclusions: SOMET is a simple modified technique using minimal oral mucosal tissue to regenerate epithelialization for complicated ocular surface reconstruction such as a complete ankyloblepharon repair. Although there was evidence of conjunctival invasion, stable ocular surface and deep fornices can be achieved for further visual rehabilitative procedure.
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http://dx.doi.org/10.1097/ICO.0000000000002638DOI Listing
November 2021

Effect of herpes simplex keratitis scar location on bilateral corneal nerve alterations: an in vivo confocal microscopy study.

Br J Ophthalmol 2020 Nov 23. Epub 2020 Nov 23.

Ocular Surface Imaging Center, Cornea and Refractive Surgery Service, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA

Aims: To evaluate the impact of herpes simplex virus (HSV)-induced scar location on bilateral corneal nerve alterations using laser in vivo confocal microscopy (IVCM).

Methods: Central and peripheral corneal subbasal nerve density (CSND) were assessed bilaterally in 39 patients with unilateral HSV-induced corneal scars (21 central scars (CS), 18 peripheral scars (PS)) using IVCM. Results were compared between patients and 24 age-matched controls. CSND was correlated to corneal sensation for all locations.

Results: Overall patients revealed significant decrease of CSND in the central and peripheral cornea (9.13±0.98 and 6.26±0.53 mm/mm, p<0.001), compared with controls (22.60±0.77 and 9.88±0.49 mm/mm). CS group showed a decrease in central (8.09±1.30 mm/mm) and total peripheral nerves (5.15±0.62 mm/mm) of the affected eyes, whereas PS group demonstrated a decrease in central (10.34±1.48 mm/mm) and localised peripheral nerves only in the scar area (4.22±0.77 mm/mm) (all p<0.001). In contralateral eyes, CSND decreased in the central cornea of the CS group (16.88±1.27, p=0.004), and in the peripheral area, mirroring the scar area in the affected eyes of the PS group (7.20±0.87, p=0.032). Corneal sensation significantly decreased in the whole cornea of the affected, but not in contralateral eyes (p<0.001). A positive correlation between CSND and corneal sensation was found in all locations (p<0.001).

Conclusions: Patients with HSV scar demonstrate bilateral CSND decrease as shown by IVCM. CSND and corneal sensation decrease in both central and peripheral cornea in affected eyes, although only in the scar area in PS group. Interestingly, diminishment of CSND was found locally in the contralateral eyes, corresponding and mirroring the scar location in the affected eyes.
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http://dx.doi.org/10.1136/bjophthalmol-2020-316628DOI Listing
November 2020

Phenotypic Characterization of Corneal Epithelium in Long-Term Follow-Up of Patients Post-Autologous Cultivated Oral Mucosal Epithelial Transplantation.

Cornea 2021 Jul;40(7):842-850

Research Division, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Purpose: To analyze the phenotype of the corneal epithelium in patients with long-term follow-up who underwent autologous cultivated oral mucosal epithelial transplantation (COMET) using in vivo confocal microscopy (IVCM) and impression cytology with immunofluorescence staining (ICIF).

Methods: Thirteen eyes from patients with severe limbal stem cell deficiency, who underwent COMET at least 48 months before, were recruited in this noncomparative cohort study. After eye examination, IVCM and ICIF were performed. Clinical manifestations of the cornea were evaluated and compared with epithelial findings detected by IVCM and ICIF [cytokeratin (CK) 3, CK7, and CK12]. Two corneal buttons derived from patients receiving the corneal transplantation post-COMET were sent for immunohistochemistry (CK3, CK6, CK7, CK12, paired box gene 6, p63, zonula occludens-1, and integrin β -1).

Results: The mean age of patients was 51.2 ± 20.6 years, and the mean follow-up time since COMET was 78.7 ± 16.3 months. Six of 13 eyes showed clinically successful COMET. In these eyes, IVCM demonstrated predominant cornea-like epithelium and ICIF reported positivity for CK3 and CK12, confirming the presence of oral mucosal and corneal epithelium. Meanwhile, 7 eyes showed total conjunctivalization, corresponding with substantial conjunctival epithelium detected by IVCM and positivity for conjunctival (CK7) and oral mucosal epithelial (CK3) markers detected by ICIF. The immunohistochemistry of corneal buttons stained positive for oral mucosal, corneal epithelial, and stem cell markers (CK3, CK12, and p63).

Conclusions: In long-term follow-up of COMET, epithelium of successful patients demonstrated cornea-like phenotype, whereas failed cases revealed mainly conjunctival phenotype. However, there were evidences that oral mucosal epithelial cells remained across the cornea in both successful and failed COMET as detected by IVCM and ICIF.
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http://dx.doi.org/10.1097/ICO.0000000000002498DOI Listing
July 2021

Characterization of limbal explant sites: Optimization of stem cell outgrowth in in vitro culture.

PLoS One 2020 14;15(5):e0233075. Epub 2020 May 14.

Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Simple limbal epithelial transplantation (SLET) and cultivated limbal epithelial transplantation (CLET) are proven techniques for treating limbal stem cell deficiency (LSCD). However, the precise regions that are most suitable for preparing explants for transplantation have not been identified conclusively. Accordingly, this in vitro study aimed at determining ideal sites to be selected for tissue harvest for limbal stem cell culture and transplantation. We evaluated cell outgrowth potential and the expression of stem cell markers in cultures from 48 limbal explants from five cadaveric donors. The limbal explants were generated from the three specific sites: Lcor (located innermost and adjacent to the cornea), Lm (middle limbus), and Lconj (located outermost adjacent to the conjunctiva). We found that explants from the Lconj and Lm sites exhibited higher growth potential than those from the Lcor site. Transcript encoding the stem cell marker and p63 isoform, ΔNp63, was detected in cells from Lm and Lconj explants; expression levels were slightly, though significantly (p-value < 0.05), higher in Lm than in Lconj, although expression of ΔNp63α protein was similar in cells from all explants. Differential expression of ATP-Binding Cassette Subfamily G Member 2 (ABCG2) did not reach statistical significance. Immunohistochemistry by indirect immunofluorescence analysis of limbus tissue revealed that the basal layer in explant tissue from Lconj and Lm contained markedly more stem cells than found in Lcor explant tissue; these findings correlate with a higher capacity for growth. Collectively, our findings suggest that explants from the Lconj and Lm sites should be selected for limbal cell expansion for both CLET and SLET procedures. These new insights may guide surgeons toward specific limbal sites that are most suitable for stem cell culture and transplantation and may ultimately improve treatment outcomes in the patients with LSCD.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0233075PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224544PMC
August 2020

Efficacy of Swept-source Optical Coherence Tomography in Axial Length Measurement for Advanced Cataract Patients.

Optom Vis Sci 2020 03;97(3):186-191

Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Significance: A major limitation of standard time-domain optical coherence tomography-based biometers (TD-OCT) is an inability to measure the axial length (AL) in advanced cataract. A new device that uses swept-source optical coherence tomography (SS-OCT) allows better light penetration. Hence, a considerable number of cataract patients who failed AL measurement by TD-OCT can be recovered by SS-OCT.

Purpose: The purposes of this study were to evaluate the efficacy of an SS-OCT for AL measurement in advanced cataract patients and to identify characteristics of lens opacity that impede the AL measurement.

Methods: Advanced cataract patients who were unable to obtain AL measurement using a standard TD-OCT-based optical biometer (IOLMaster500; Carl Zeiss Meditec, Jena, Germany) were recruited in this study. The AL was remeasured using SS-OCT (IOLMaster700), followed by measurement with immersion ultrasonography (IU). The percentage of patients who achieved AL measurement by SS-OCT was recorded. The AL obtained from SS-OCT was then verified by comparing with the AL derived from IU. The cataract type of each patient was classified according to standard Lens Opacity Classification III score. The association between characteristics of cataract and successful AL measurement by SS-OCT was analyzed.

Results: Sixty-four eyes that failed AL measurement from TD-OCT were included. Fifty-six eyes (87.5%) were able to be measured by SS-OCT (95% confidence interval, 77.23 to 93.53%). The AL obtained by SS-OCT showed very high agreement with those derived from IU (intraclass correlation coefficient, 0.99). There was no statistically significant correlation between characteristics of lens opacity and the capability of SS-OCT for AL measurement (P > .05). However, there was a trend toward an inability to measure the AL in cataracts with a high grade of lens opacity.

Conclusions: The efficacy of SS-OCT-based optical biometer was excellent. Of the patients with advanced cataract who failed the AL measurement by TD-OCT, 87.5% could be recovered by SS-OCT. However, there was no specific type of lens opacity associated with a failure of AL measurement using SS-OCT.
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http://dx.doi.org/10.1097/OPX.0000000000001491DOI Listing
March 2020

Eyeliner Induces Tear Film Instability and Meibomian Gland Dysfunction.

Cornea 2020 Apr;39(4):473-478

Research Division, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Purpose: To compare the degree of tear film instability and severity of meibomian gland dysfunction between subjects who use eyeliner and those who do not use eyeliner.

Methods: This cross-sectional study included 42 healthy volunteer women who had no dry eye symptoms (Ocular Surface Disease Index score < 13) and aged between 18 and 40 years. The subjects were classified into 2 groups: an eyeliner-use group (EL: regularly used eyeliner ≥3 d/wk and continuously used ≥6 mo) and a noneyeliner-use group as controls. A questionnaire for ocular surface symptoms using a visual analog scale was administered. Then, a number of eye tests were performed [grading of conjunctival inflammation, fluorescein tear breakup time, ocular surface fluorescein staining, Schirmer I, evaluation of meibomian gland (MG) function, detection of eyelid margin abnormalities, and Demodex detection].

Results: Tear breakup time was significantly lower in the EL group compared with controls (3.0 ± 1.9 vs. 5.8 ± 2.1 s, P < 0.001). MG grading was significantly higher in the EL group than in controls (P = 0.004); higher grade (grades 2-3) was found in 85.7% of EL and 47.6% of controls. Meiboscore was also higher in EL than in controls (P = 0.001). Regarding the morphological changes in lid margin, only telangiectasia was detected significantly more in EL (28.6%) compared with controls (4.8%) (P = 0.041). Conjunctival inflammation was observed 4 times more in EL (66.7%) than in controls (14.3%), P = 0.001. Other outcomes included ocular surface symptoms and fluorescein staining scores, and Schirmer I and Demodex detection were not significantly different between both groups.

Conclusions: The regular use of eyeliner induces tear film instability and MG dysfunction.
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http://dx.doi.org/10.1097/ICO.0000000000002198DOI Listing
April 2020

Comparison of refractive outcomes using conventional keratometry or total keratometry for IOL power calculation in cataract surgery.

Graefes Arch Clin Exp Ophthalmol 2019 Dec 5;257(12):2677-2682. Epub 2019 Sep 5.

Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Prannok Road, Bangkok, 10700, Thailand.

Purpose: To compare the refractive outcomes following cataract surgery using conventional keratometry (K) and total keratometry (TK) for intraocular lens (IOL) calculation in the SRK/T, HofferQ, Haigis, and Holladay 1 and 2, as well as Barrett and Barrett TK Universal II formulas.

Methods: Sixty eyes of 60 patients from Siriraj Hospital, Thailand, were prospectively enrolled in this comparative study. Eyes were assessed using a swept-source optical biometer (IOLMaster 700; Carl Zeiss Meditec, Jena, Germany). Posterior keratometry, K, TK, central corneal thickness, anterior chamber depth, lens thickness, axial length, and white-to-white corneal diameter were recorded. Emmetropic IOL power was calculated using K and TK in all formulas. Selected IOL power and predicted refractive outcomes were recorded. Postoperative manifest refraction was measured 3 months postoperatively. Mean absolute errors (MAEs), median absolute errors (MedAEs), and percentage of eyes within ± 0.25, ± 0.50, and ± 1.00 D of predicted refraction were calculated for all formulas in both groups.

Results: Mean difference between K and TK was 0.03 D (44.56 ± 1.18 vs. 44.59 ± 1.22 D), showing excellent agreement (ICC = 0.99, all p < 0.001). Emmetropic IOL powers in all formulas for both groups were very similar, with a trend toward lower MAEs and MedAEs for TK when compared with K. The Barrett TK Universal II formula demonstrated the lowest MAEs. Proportion of eyes within ± 0.25, ± 0.50, and ± 1.00 D of predicted refraction were slightly higher in the TK group.

Conclusions: Conventional K and TK for IOL calculation showed strong agreement with a trend toward better refractive outcomes using TK. The same IOL constant can be used for both K and TK.
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http://dx.doi.org/10.1007/s00417-019-04443-7DOI Listing
December 2019

In Vivo Confocal Microscopy Demonstrates Increased Immune Cell Densities in Corneal Graft Rejection Correlating With Signs and Symptoms.

Am J Ophthalmol 2019 07 18;203:26-36. Epub 2019 Feb 18.

Ocular Surface Imaging Center, Cornea and Refractive Surgery Service, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA; Center for Translational Ocular Immunology, and Cornea Service, New England Eye Center, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts, USA. Electronic address:

Purpose: Diagnosis of graft rejection is based on patient symptoms and on clinical signs detected by slit-lamp biomicroscopy. This study investigated whether laser in vivo confocal microscopy (IVCM) can aid in the diagnosis of corneal graft rejection by detecting cellular corneal changes that take place after transplantation.

Design: Prospective case-control study.

Subjects: Thirty-eight eyes of 38 patients with penetrating keratoplasty (15 eyes with corneal graft rejection, 23 eyes without rejection) and 9 age-matched normal controls.

Methods: Laser IVCM was performed in the corneal grafts centrally. The density of immune cells (IC) was assessed for epithelial, sub-epithelial, stromal, and endothelial layers by 2 masked observers. IC density was compared among different groups and correlated to clinical signs and symptoms of corneal graft rejection.

Main Outcome Measurements: Outcome measurement was the IC density in the corneal layers and its associations with the presence of clinical signs and symptoms of corneal graft rejection.

Results: The IC density was significantly different between rejected and non-rejected grafts (P = 0.004) and different from that of normal controls (P = 0.001). Among corneal layers, IC density was significantly higher in rejected grafts than in non-rejected grafts in only the sub-basal (611.54 ± 573.74 vs. 340.61 ± 268.60 cells/mm, respectively; P = 0.049) and endothelial layers (250.62 ± 267.13 vs. 103.47 ± 81.91 cells/mm, respectively; P = 0.001). Patients with decreased best corrected visual acuity, Khodadoust line, and anterior chamber cells demonstrated a significant increase in total IC density (P < 0.05), whereas patients with symptoms of irritation, light sensitivity, and pain revealed a specific increase in IC density in the sub-basal layer (P < 0.05). Patients with ocular pain had higher IC density in the epithelial layer than those without pain (P = 0.03).

Conclusions: Patients with corneal graft rejection demonstrate a significant increase in corneal immune cells, particularly, in the sub-basal and endothelial layers compared to patients with non-rejected grafts and controls. Although symptoms associated with endothelial rejection demonstrate a general increase in IC, pain, irritation, and light sensitivity are associated with increased IC in the sub-basal layer. Assessment of patients with corneal graft rejection by IVCM may serve as an adjunctive tool in the diagnosis and management of corneal graft rejection.
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http://dx.doi.org/10.1016/j.ajo.2019.02.013DOI Listing
July 2019

Epithelial analysis of simple limbal epithelial transplantation in limbal stem cell deficiency by in vivo confocal microscopy and impression cytology.

Cell Tissue Bank 2019 Mar 24;20(1):95-108. Epub 2019 Jan 24.

Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Simple limbal epithelial transplantation (SLET) is a relatively new treatment for severe limbal stem cell deficiency. Outcomes of treatment are typically determined based on clinical manifestations. In this prospective-multicenter study, we aimed to analyze the epithelial phenotypes of the corneas after SLET using IVCM and IC, and correlated them with clinical findings. Ten eyes of nine patients, who underwent SLET (five autologous SLET and five living-related SLET) were recruited. A set of examinations included slit-lamp biomicroscopy, corneal in vivo confocal microscopy (IVCM), and impression cytology (IC) was performed in all eyes at least twice (≥ 3-month interval) postoperatively. Then, a correlation between findings of the three examinations was analyzed. There were seven eyes with clinical success (no central neovascularization) showed pure corneal epithelial phenotype or mixed corneal-conjunctival phenotypes (mostly cornea) in either IVCM or IC. Three eyes with clinical failure, presented with peripheral and central neovascularization, showed total or predominant conjunctival phenotype in IVCM and sole conjunctival phenotype in IC. From a total of 22 sets of examinations, there was a high correlation between clinical manifestation vs. IC (κ = 0.844, observed agreement = 81.82%) and a substantial correlation between clinical manifestation vs. IVCM (κ = 0.727, observed agreement = 76.19%) and between IVCM versus IC (κ = 0.729, observed agreement = 76.19%). In conclusion, IVCM and IC facilitate determination of epithelial phenotype of the cornea after SLET. There was a substantial to high correlation between IVCM, IC and clinical presentations. Findings observed by IVCM and IC may allow early detection of epithelial alterations in eyes underwent SLET before clinical recognition.
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http://dx.doi.org/10.1007/s10561-018-09746-3DOI Listing
March 2019

Ocular Injury due to Potassium Permanganate Granules.

Case Rep Ophthalmol 2018 Jan-Apr;9(1):132-137. Epub 2018 Feb 8.

Department of Ophthalmology, Sawanpracharak Hospital, Nakhon Sawan, Thailand.

Purpose: We report a rare case of ocular injury due to potassium permanganate (KMnO) granules in a child.

Methods: This is a retrospective case report.

Results: A 2-year-old boy was transferred to our emergency room with severe pain in his right eye, inflamed eyelids, and brownish stains on his fingers. Chemical injury was suspected. Copious eye irrigation was immediately performed. Diffuse brownish splotches were then observed at the inferior bulbar conjunctiva. Otherwise, systemic organs were intact. Complete eye exam under general anesthesia revealed a 5-mm epithelial defect at the central cornea, along with generalized conjunctival injection and limbal ischemia, inferiorly. Multiple semi-dissolved granules of KMnO trapped in the inferior fornix were identified. The chemical particles were gradually washed out and removed; however, the brownish stains remained. The patient received preservative-free steroid, antibiotic eye drops, and lubricants as regular management for mild to moderate degree of ocular burn. Pseudomembrane developed early and transformed into symblepharon within a few days after the injury. Membrane adhesion was lysed, and more aggressive medications were then substituted. Commercial amniotic membrane (PROKERA®) was also applied to promote wound healing and to prevent recurrence of symblepharon. The ocular surface was eventually restored, and corneal transparency was preserved.

Conclusion: Ocular injury with the granular form of KMnO is rare. Its toxicity is comparable to concentrated KMnO solution. However, the dissolved particles that had been absorbed in the stained conjunctiva were continuously released and damaged the ocular surface more than we primarily anticipated. Awareness of this condition and prompt management yield a good treatment outcome.
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http://dx.doi.org/10.1159/000486922DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5892315PMC
February 2018

Clinical comparison of a new swept-source optical coherence tomography-based optical biometer and a time-domain optical coherence tomography-based optical biometer.

J Cataract Refract Surg 2015 Oct;41(10):2224-32

From the Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Purpose: To evaluate the repeatability and reproducibility of a newer swept-source optical biometer and to compare it with a standard partial coherence interferometry (PCI) biometer.

Setting: Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Design: Prospective comparative study.

Methods: One hundred eyes from 100 cataract patients were enrolled in this study. Each patient was measured with 2 optical biometers, a newer swept-source optical biometer (IOLMaster 700) and a standard partial coherence interferometry biometer (IOLMaster 500) by 2 independent operators. The keratometry, axial length (AL), anterior chamber depth, white-to-white corneal diameter, and intraocular lens (IOL) power, calculated by the SRK/T and the Haigis formulas for each device, were recorded. Intraoperator repeatability and interoperator reproducibility of both devices were analyzed using intraclass correlation coefficients (ICCs). Agreement of ocular biometry and IOL power between the 2 devices was evaluated using the Bland-Altman method.

Results: The repeatability and reproducibility of the swept-source and standard biometers were high for all ocular biometry parameters (ICC, 0.93-1.00). The agreement between the 2 biometers was also high (ICC, 0.92-1.00). The IOL powers obtained from both devices were not distinct. Because of the density of the cataracts, the AL in 5 eyes could be measured only by the swept-source biometer.

Conclusions: Repeatability and reproducibility of a swept-source optical biometer was excellent and agreement with a standard biometer was very high. Better lens penetration ability and AL measurements were obtained with the swept-source biometer than with the standard biometer.

Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.
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http://dx.doi.org/10.1016/j.jcrs.2015.03.019DOI Listing
October 2015

Comparison of corneal astigmatism measurements of 2 optical biometer models for toric intraocular lens selection.

J Cataract Refract Surg 2015 Feb;41(2):364-71

From the Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Purpose: To compare corneal astigmatism measurements obtained using a new optical biometer (AL-Scan) and a standard biometer based on partial coherence interferometry (IOLMaster 500) for toric intraocular lens (IOL) selection.

Setting: Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Design: Prospective comparative study.

Methods: Keratometry (K) readings were taken with the 2 biometers in eyes of cataract patients. The corneal astigmatism readings from the 2 devices were compared. The cylinder measurements were transformed into J0 and J45 vector components for analysis, and the devices' values were compared using the paired t test. Correlation coefficients were calculated. The Bland-Altman method was used to evaluate the agreement between the sets of measurements.

Results: One hundred thirty-seven eyes (81 patients) were enrolled. The magnitude of astigmatism between the new biometer 2.4 mm zone and the standard biometer was similar (P = .19). There was a statistically significant difference between values from the new biometer 3.3 mm zone and the standard biometer (P < .05). There was good correlation in the overall magnitude of astigmatism between devices. There was a trend of low correlation toward the flat cornea (K <43.0 diopters [D]), low corneal cylinder (<1.0 D), and with-the-rule astigmatism. The IOL toricity calculated from both devices was similar.

Conclusions: Corneal astigmatism measurements with the 2 biometers were similar in magnitude, especially in 2.4 mm zone of the new biometer. There was no difference in the toric IOL selections between the devices.

Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.
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http://dx.doi.org/10.1016/j.jcrs.2014.06.029DOI Listing
February 2015

Comparison of ocular biometry and intraocular lens power using a new biometer and a standard biometer.

J Cataract Refract Surg 2014 May 18;40(5):709-15. Epub 2014 Mar 18.

From the Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Purpose: To compare the repeatability and reproducibility of ocular biometry and intraocular lens (IOL) power obtained with a new optical biometer (AL-Scan) and a standard optical biometer (IOLMaster 500).

Setting: Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Design: Prospective comparative study.

Methods: Two independent operators measured eyes with cataract using both biometers. The keratometry values, axial length, anterior chamber depth, white-to-white (WTW) corneal diameter, and IOL power calculated using the Holladay 1 formula obtained with each device were recorded. Intraoperator repeatability and interoperator reproducibility of both devices were analyzed using the intraclass correlation coefficient (ICC). The agreement in ocular biometry and IOL power between the 2 devices was evaluated by the Bland-Altman method.

Results: The study recruited 137 eyes of 81 patients. The repeatability and reproducibility of both devices were high for all ocular biometry measurements (ICC, 0.87-1.00). Except for the WTW corneal diameter (ICC, 0.44), the agreement between the biometers was also high (ICC, 0.98-0.99). The IOL powers calculated by the Holladay 1 formula were similar between the 2 biometers.

Conclusion: The new optical biometer provided excellent repeatability and reproducibility for all ocular biometry. Agreement with the standard optical biometer was good except for the WTW corneal diameter.
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http://dx.doi.org/10.1016/j.jcrs.2013.09.020DOI Listing
May 2014

Accuracy of Holladay 2 formula using IOLMaster parameters in the absence of lens thickness value.

Graefes Arch Clin Exp Ophthalmol 2013 Nov 15;251(11):2563-7. Epub 2013 Aug 15.

Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Background: The accuracy of the Holladay 2 (H2) formula is well-documented. This formula requires seven variables to estimate effective lens position (ELP) for the IOL power calculation. The lens thickness (LT) value is one of the required variables. Interestingly, the IOLMaster, which is one of the most commonly used optical biometers, can provide all the required ocular variables except LT value. It has become a pertinent issue to evaluate the accuracy of theH2 formula when it is used without the LT value. The purpose of this study was to evaluate the results when using the H2 formula, without the LT value, and compare such results to those obtained using the Haigis formula and the Hoffer Q formula.

Methods: The Institutional review board (IRB) gave their approval for the conduct of this prospective comparative study. One hundred and sixty-three eyes of 143 cataract patients from the Ophthalmology Department, Siriraj Hospital, Thailand were recruited. All eyes were measured using the IOLMaster (Carl Zeiss Meditec, Jena, Germany) for keratometry (K), axial length (AL), anterior chamber depth (ACD), and horizontal white-to-white (WTW) corneal diameter. Then, the LT measurement was obtained by A-scan ultrasonography (Quantel Axis-II, Quantel Medical, USA). Every patient underwent uncomplicated phacoemulsification by a single surgeon (NC) with a single technique using a single IOL model. Post-operative refraction was obtained at 3 months. The mean absolute errors (MAEs), median absolute errors (MedAEs) and percentage of the eyes within ±0.25, ±0.50, and ±1.00 D of predicted refraction was calculated for H2 formula both with and without LT input, Haigis, and Hoffer Q formula. The results were also classified into a group of short AL (<22.0 mm), average AL (22.0 to 24.5 mm) and long AL (>24.5 mm).

Results: There was no statistically significant difference in either MAEs or MedAEs of all formulas in all AL groups including the H2 with and without LT. There was a trend toward lower MAEs and MedAEs for H2 in the long AL group. Percentage of the eyes within ±0.25, ±0.50, and ±1.00 D of predicted refraction were similar in all AL groups.

Conclusion: The preliminary results of this study showed that the H2 formula performed well even without the LT value. It was comparable to the Haigis and Hoffer Q formulas.
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http://dx.doi.org/10.1007/s00417-013-2439-8DOI Listing
November 2013

Agreement of IOL power and axial length obtained by IOLMaster 500 vs IOLMaster 500 with Sonolink connection.

Graefes Arch Clin Exp Ophthalmol 2013 Apr 12;251(4):1145-9. Epub 2013 Jan 12.

Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Background: The accurrate and expedient ocular biometry is essential for modern cataract surgery. IOLMaster 500, one of the most popular partial coherence interferometry (PCI) device, has been widely used. However, with the PCI device, it is difficult to obtain the axial length through densely opaque media. With the current version of IOLMaster 500, a unique feature is added to link with the Synergy immersion A-scan ultrasound (sonolink connection). In case of failure to measure axial length by IOLMaster 500, the axial length can be obtained by ultrasound, and then transferred to IOLMaster 500 for the IOL power calculation. This study aims to compare the results and evaluate the agreement between IOL power and axial length obtained by IOLMaster 500 and IOLMaster 500 with sonolink connection.

Methods: A prospective study of 60 eyes in 60 mild-to-moderate cataract patients was conducted under Institutional Ethics Committee approval. Keratometry (K) and axial length (AL) of all eyes were measured using IOLMaster 500 (Carl Zeiss, Germany), then IOL power was generated using Holladay 1 formula (group 1). After 5 min, the K measurements were repeated with IOLMaster 500 and the AL were measured again using the Synergy A-scan ultrasound (Accutome, USA). Then, the AL data were transferred to IOLMaster 500 via the sonolink connection to generate the IOL power using the same setting (group 2). The IOL power and AL were compared between the two groups, and the agreement was evaluated using intraclass correlation coefficient (ICC) and the Bland-Altman method.

Results: The mean IOL power in group 1 was 21.04 + 2.36 D and group 2 was 21.03 + 2.36 D. The mean AL in group 1 was 23.35 + 0.86 mm and in group 2 was 23.36 + 0.86 mm. There was no statistically significant difference in IOL power and AL between the two groups. The agreements in IOL power and AL between both groups were high (ICCs = 0.997 for IOL power and 0.993 for AL) CONCLUSIONS: The IOL power and AL derived from both groups were similar. The agreements between them were high.
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http://dx.doi.org/10.1007/s00417-012-2222-2DOI Listing
April 2013

Comparison of corneal astigmatism and axis location in cataract patients measured by total corneal power, automated keratometry, and simulated keratometry.

J Cataract Refract Surg 2012 Dec 15;38(12):2088-93. Epub 2012 Sep 15.

Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Purpose: To compare the corneal astigmatism (magnitude and axis location) derived by total corneal power (TCP), automated keratometry, and simulated keratometry.

Setting: Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Design: Prospective comparative study.

Methods: Eyes with previous ocular surgery or abnormalities were excluded. All patients were examined with the ARK 730A autokeratometer and the Galilei analyzer. The steepest and flattest corneal power along with the steepest axis of the TCP, automated keratometry, and simulated keratometry were recorded. Vector analysis (J0 and J45) was calculated. Analysis of variance with Bonferroni correction was performed for multiple comparisons. Outcome measures were the magnitude and axis location of astigmatism.

Results: One hundred eyes of 100 cataract patients were randomly selected. There was no statistically significant difference in the mean steepest axis between TCP (93.31 ± 68.75 [SD]), automated keratometry (94.24 ± 64.78), and simulated keratometry (92.42 ± 64.30). However, the mean magnitude of astigmatism measured by TCP (1.23 ± 0.75) was significantly higher than that measured by automated keratometry (0.93 ± 0.68) (P=.01) but not than that measured by simulated keratometry (1.08 ± 0.68) (P=.43); there was no statistically significant difference in J0 or J45. Twenty two (40%) of 54 eyes with more than 1.00 diopter of TCP astigmatism had more than 10 degrees of axis difference from automated keratometry.

Conclusions: The magnitude of TCP astigmatism was higher than that of automated keratometry. The axis location was similar. However, there was more than 10 degrees of axis difference between automated keratometry and TCP in patients with high astigmatism.

Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.
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http://dx.doi.org/10.1016/j.jcrs.2012.07.024DOI Listing
December 2012

Precision analysis of posterior corneal topography measured by Visante Omni: repeatability, reproducibility, and agreement with Orbscan II.

J Refract Surg 2012 Feb 2;28(2):133-8. Epub 2011 Dec 2.

Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Purpose: To evaluate the repeatability and reproducibility of posterior corneal curvature and posterior corneal elevation best-fit sphere (BFS) obtained with the Visante Omni (Carl Zeiss Meditec) and to compare the results with the Orbscan II (Bausch & Lomb).

Methods: Thirty eyes from 30 healthy volunteers were included in this study. All patients were examined 5 times with the Visante Omni and Orbscan II by 2 independent operators. The posterior corneal curvature (3- and 6-mm zone) and posterior corneal elevation BFS (5- and 8-mm zone) were generated for each system. Intraoperator repeatability and interoperator reproducibility and agreement between the systems were evaluated using the intraclass correlation coefficient (ICC) and the Bland-Altman method.

Results: The repeatability of posterior corneal curvature and posterior corneal elevation BFS measured by the Visante Omni was high for all analysis zones (ICC, 0.99 to 1.00). The reproducibility also showed similar results (ICC, 0.99 to 1.00). Agreement between the Visante Omni and Orbscan II was high for posterior corneal curvature (ICC, 0.94 to 0.97) and posterior corneal elevation BFS (ICC, 0.96 to 0.98) with 95% limits of agreement at -0.26 to 0.22 diopters for posterior corneal curvature and 0.11 to 0.69 mm for posterior corneal elevation BFS.

Conclusions: The Visante Omni provides good repeatability and reproducibility of posterior corneal topography. Overall agreement with the Orbscan II system was high.
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http://dx.doi.org/10.3928/1081597X-20111122-03DOI Listing
February 2012
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