Adisak Trinavarat

Whole Exome Sequencing in Thai Patients With Retinitis Pigmentosa Reveals Novel Mutations in Six Genes

PURPOSE To identify disease-causing mutations and describe genotype-phenotype correlations in Thai patients with nonsyndromic retinitis pigmentosa (RP). METHODS Whole exome sequencing was performed in 20 unrelated patients. Eighty-six genes associated with RP, Leber congenital amaurosis, and cone-rod dystrophy were analyzed for variant detection. RESULTS Seventeen variants (13 novel and 4 known) in 13 genes were identified in 11 patients. These variants include 10 missense substitutions, 2 nonsense mutations, 3 deletions, 1 insertion, and 1 splice site change. Nine patients with identified inheritance patterns carried a total of 10 potentially pathogenic mutations located in genes CRB1, C8orf37, EYS, PROM1, RP2, and USH2A. Three of the nine patients also demonstrated additional heterozygous variants in genes ABCA4, GUCY2D, RD3, ROM1, and TULP1. In addition, two patients carried variants of uncertain significance in genes FSCN2 and NR2E3. The RP phenotypes of our patients were consistent with previous reports. CONCLUSIONS This is the first report of mutations in Thai RP patients. These findings are useful for genotype-phenotype comparisons among different ethnic groups.

Neodymium:YAG laser damage threshold of foldable intraocular lenses

Purpose: To determine the energy level of the neodymium:YAG (Nd:YAG) laser that induced a 50% incidence of intraocular lens (IOL) damage in 5 foldable IOL materials. Setting: Department of Ophthalmology, Siriraj Hospital Mahidol University, Bangkok, Thailand. Methods: To simulate the condition within the capsular bag, an IOL was sandwiched between 2 rubber membranes. The front membrane had a central opening mimicking the anterior capsulotomy; the back membrane acted as the posterior capsule. The model was submerged in a water‐filled chamber. The Nd:YAG laser with an automatic focus 150 &mgr;m beyond the focus of the aiming beam was used to perform a posterior capsulotomy. Three IOLs of each of 5 foldable IOL materials were tested. One type of poly(methyl methacrylate) (PMMA) was studied as a reference. The incidence of IOL damage at various energy levels was recorded. Linear regression analysis was used to determine the 50% incidence damage threshold. Results: The 6 materials tested included 1 silicone lens (SI‐40NB, AMO), 1 hydrophobic acrylic lens (MA60BM, Alcon), 3 hydrophilic acrylic lenses (Haptibag Ang, IOLtech; ACR6D, Corneal; H60M, Bausch & Lomb), and 1 PMMA lens (LX10BD, Alcon). The 50% incidence damage threshold values were 0.37 mJ, 0.54 mJ, 0.58 mJ, 0.52 mJ, 0.66 mJ, and 0.68 mJ, respectively. Conclusions: The 50% incidence damage threshold in all the IOLs was below the energy level normally used to perform a posterior capsulotomy in clinical practice. However, setting the laser at the lowest possible energy, focusing the laser beam beyond the posterior capsule, and performing the capsulotomy early should minimize the risk of IOL damage.

Reduction of endophthalmitis rate after cataract surgery with preoperative 5% povidone-iodine.

Objective: Postoperative endophthalmitis reflects in part quality and safety aspects of cataract surgery. Preoperative 5% povidone-iodine was introduced as a quality improvement effort. This study evaluated the effect of this additional measure on the occurrence of endophthalmitis after cataract surgery. Method: Topical 5% povidone-iodine solution was applied onto the ocular surface just prior to transferring the patient into the operative theater for cataract surgery. Other prophylactic measures were allowed to continue as before. Patients developing postoperative intraocular inflammation and undergoing intravitreal antibiotic injection were included as occurrences of endophthalmitis. Alteration in endophthalmitis rate was analyzed using a ‘p control chart’ of a statistical process control method. The incidence in the povidone-iodine-receiving group was compared to those before implementation and concurrent nonreceiving groups. Result: The postoperative endophthalmitis rate showed a significant reduction after introduction of povidone-iodine. A year before, 9 of 3,052 eyes developed endophthalmitis (0.294%). After introduction, this occurred in 4 of 4,089 eyes receiving povidone-iodine (0.097%) and 1 of 502 nonreceiving eyes (0.199%) in the following 16 months. Despite the apparent lower rate, comparison between groups was not statistically significant. Moderate to severe but tolerable eye irritation after application was reported in 6.6%. No other adverse events were detected. Conclusion: Topical preoperative 5% povidone-iodine contributed an additional effect to the reduction of the postoperative endophthalmitis rate after cataract surgery. This measure was rather safe to apply as a prophylaxis against endophthalmitis in cataract surgery.

Applicability of American and British Criteria for Screening of the Retinopathy of Prematurity in Thailand

PurposeThe aim of this study was to verify the applicability of standard guidelines for the screening of retinopathy of prematurity (ROP) and to determine the appropriate criteria for Thai neonates.MethodsRecords of ROP screening of infants born in our hospital between 1995 and 2000 with a birth weight below 2000 g or a gestational age of less than 36 weeks were studied. Criteria to screen infants with a birth weight below 1500 g or a gestational age of less than 28 weeks in the American guidelines and similar birth weight but a gestational age of less than 31 weeks in the British recommended guidelines were applied and evaluated in terms of sensitivity and specificity. Criteria reaching 100% sensitivity with the maximum specificity were deemed appropriate.ResultsOf the 514 screened infants, 33 had developed stage 2+ ROP and beyond. The mean ± SD birth weight and gestational age were 1046 ± 257 (710–1680 g) and 29.2 ± 2.5 weeks (24–35 weeks), respectively. The age at intervention was 6–16 weeks. Sensitivity for both American and British guidelines was 93.9%. By screening infants with birth weights below 1500 g or gestational age less than 33 weeks, we could achieve 100% sensitivity with 18.3% specificity. We decided that the initial examination should be performed 4–6 weeks after birth. By applying these criteria to 62 referred cases we also were able to include in the screening all cases of concern in this group.ConclusionsRegional criteria for ROP screening is required and should be evaluated periodically and modified accordingly. Jpn J Ophthalmol 2004;48:50–53

Treatment of Epidemic Keratoconjunctivitis with 2% Povidone–Iodine: A Pilot Study

PURPOSE The purpose of this study was to analyze the outcome of treating epidemic keratoconjunctivitis (EKC) with 2% povidone-iodine (PVP-I) solution. METHODS A prospective, interventional, uncontrolled study was performed in participants diagnosed with EKC. PVP-I was applied to the affected eyes 4 times a day for a week. Participants were informed about transient eye stinging and discoloration after application. Drug discontinuation was allowed for early recovery or encountering any adverse effects. Data collection included history, symptoms, and signs at the initial presentation and at 1 week. Main outcomes were the recovery rate within a week of treatment and drug tolerability. RESULTS Of 172 enrolled, 61 participants completed the study. EKC occurred bilaterally in 40 participants (66%). Single eye from each participant was included for analysis. The mean (standard deviation) time elapsed before treatment was 2.1 (1.46) days. The recovery rate within a week of treatment was 77% (95% confidence interval, 65.1-85.8). Twenty-eight participants (45.9%) recovered within a week after the onset. Application of PVP-I was sustained until recovery or completing a 7-day trial in 78.7%. No severe ocular or systemic adverse effects have been reported related to this treatment. CONCLUSIONS Ocular application of 2% PVP-I was tolerable. This measure successfully relieved ocular discomfort from EKC in 3 quarters of the study group within a week. A randomized, controlled trial is required to verify the benefit of this measure.

Novel and De-novo Truncating PAX6 Mutations and Ocular Phenotypes in Thai Aniridia Patients

Purpose: To describe the ophthalmic findings and mutation analyses of the PAX6 gene in Thai aniridia patients. Methods: Ten patients from six unrelated families underwent a comprehensive ophthalmic examination. Mutations in the PAX6 gene were screened by single-strand conformational polymorphism (SSCP) and direct DNA sequencing of the SSCP variants. Results: Seven patients developed cataracts and six developed glaucoma. Mutation analysis demonstrated four different truncating mutations, two of which were de novo. These included one novel insertion/deletion mutation (c.474del12insGA in exon 5) and three nonsense mutations. R203X and R240X are common recurrent mutations, while Q277X in exon 10 is novel. All mutations resulted in loss of function of the PAX6 protein. Conclusion: Our data confirm inter- and intrafamilial variable phenotypic manifestations of which the underlying mechanisms may be haploinsufficiency or dominant-negative mutation.

A Novel H572R Mutation in the Transforming Growth Factor-β-Induced Gene in a Thai Family with Lattice Corneal Dystrophy Type I

PurposeTo describe a large Thai family with lattice corneal dystrophy (LCD) type I and to determine whether this LCD is associated with mutations within the transforming growth factor-β-induced (TGFBI) gene.MethodsA six-generation family with LCD type I was identified and diagnosed on the basis of clinical and/or histopathologic evaluation. Visual acuity testing and slit-lamp biomicroscopic evaluation were carried out and corneal photography was documented. All 17 exons and flanking intron sequences of the TGFBI gene were sequenced.ResultsThirty-three participants demonstrated LCD in both eyes, most of which was symmetrical. Age at onset of decreased vision was the mid- to late twenties. Visual acuity varied from 6/6 to no light perception. Two patients, 74 and 42 years of age, demonstrated a thick yellowish plaque covering the corneal surfaces. DNA sequencing revealed a heterozygous mutation in exon 13 (A1762G), changing histidine to arginine at codon 572 (H572R). Ten of 42 clinically unaffected family members, all under 25 years of age, exhibited the same mutation.ConclusionsThis is the first report of a molecular analysis of LCD type I in Thai patients. The novel mutation identified is associated with distinct phenotypes and later onset of the disease compared with the more common R124C mutation. Jpn J Ophthalmol 2006;50:403–408

Effective pupil dilatation with a mixture of 0.75% tropicamide and 2.5% phenylephrine: A randomized controlled trial.

Purpose: To compare the efficacy in pupil dilatation between a mixture containing 0.75% tropicamide and 2.5% phenylephrine and the alternate application of 1% tropicamide and 10% phenylephrine eye drops. Material and Methods: Patients requiring pupil dilatation were randomized to receive one drop of the mixture every 10 min for four times or our standard application of one drop of 1% tropicamide alternating with one drop of 10% phenylephrine every 10 min for two cycles. Pupil size was measured under bright light with the pupil gauge before, and every 5 min after initial application for 40 min. Application of the drops was discontinued once the pupil diameter reached 7 mm. Blood pressure and pulse rate were monitored every 15 min. Results: Of 40 patients (age 57.3±10.9 years, range 35-70 years), 22 were randomized into the mixture group and 18 into the alternate drug group. Baseline pupil sizes were 1.7±0.5 mm in the mixture group and 1.8±0.4 mm in the alternate drug group. The pupils were successfully dilated to 7 mm within 40 min in 17 patients of the mixture group compared to seven patients in the alternate drug group (P=0.004, Log Rank test). The mean pupil sizes at 40 min were 6.6±0.8 and 6.0±0.9 mm in the mixture and alternate drug groups respectively (P=0.050, t-test). Blood pressure and pulse rate were stable and similar in both groups. Conclusions: The mixture of 0.75% tropicamide and 2.5% phenylephrine is superior to our standard application of 1% tropicamide alternating with 10% phenylephrine. It provides faster and more successful pupil dilatation within 40 min.

Prognostic factors and treatment outcomes of retinoblastoma in pediatric patients: a single-institution study

PurposeSince 1997, our institute has used neoadjuvant chemotherapy for intraocular retinoblastoma. However, some of the patients showed signs of recurrence months to years later. We therefore attempted to determine the prognostic factors of treatment outcomes and survival in our patients.MethodsWe reviewed 90 patients treated from 1997 to 2006. The following information was recorded: demographic and ophthalmological data, clinical classification, histopathological data, and treatment methods and outcomes.ResultsEnucleation was avoided in two of 57 eyes in the unilateral group. Sixteen of 54 eyes in the bilateral group were salvaged by systemic chemotherapy with local treatment. There was no difference in histopathological findings between the two groups. Nine of 57 patients in the unilateral group demonstrated poor outcomes, compared with four of 27 in the bilateral group. Significant poor prognostic factors for survival were optic nerve head invasion, orbital involvement, abnormal results on bone marrow aspiration, lumbar puncture, bone scan, and group E or F classification.ConclusionsThe 15% mortality rate in our patients is slightly higher than that reported in developed countries. Delayed diagnosis and treatment is the main cause of avoidable deaths. Improving education of both clinicians and parents would increase survival rates in this potentially fatal disease.

Mutation Analysis of the VMD2 Gene in Thai Families with Best Macular Dystrophy

Background: To identify genetic mutations of the VMD2 gene in two Thai families with Best macular dystrophy. Materials and Methods: Ophthalmic examination including best-corrected visual acuity (BCVA), dilated fundus examination and fundus photography, and electro-oculography (EOG) was performed in two probands and their family members. Mutation screening of the VMD2 gene was performed by single-strand conformation polymorphism (SSCP) analysis followed by direct DNA sequencing of the abnormal exons. Results: The 58-year-old male proband demonstrated typical egg yolk-like macular lesion in both eyes. Mutational screening of VMD2 identified a band shift in exon 7, which was confirmed by direct DNA sequencing to be a G to A transition at position 724 bp. This novel missense mutation resulted in the change of an amino acid valine to methionine and was responsible for the abnormal Arden ratio in the probands daughter. The second male proband age 25 had a characteristic egg yolk-like macular lesion in the left eye and a scrambled egg appearance in the right. Mutation analysis identified a C to T transition at position 652 bp in exon 6. This reported missense mutation led to an amino acid substitution of cysteine for arginine. The mutation was documented in the maternal grandmother, the mother, as well as the elder sister of the proband. Conclusions: The Val-242-Met mutation is associated with a late-onset visual disturbance and the Arg-218-Cys mutation was associated with marked intra-familial clinical variability of expression. Presymptomatic testing will be available to the family members at risk with high accuracy.