Topical autologous serum promotes enucleation wound healing in retinoblastoma patients

Two retinoblastoma patients underwent uneventful enucleations while undergoing perioperative chemotherapy. In both cases the postoperative course was complicated by poor conjunctival wound healing. Administration of topical autologous serum was associated with wound healing and conjunctivalization of these wounds.

Serous retinal detachment in Joubert syndrome

This report describes a 3-year-old Chinese-Italian boy with Joubert syndrome. Fundus examination showed bilateral optic disc coloboma. Left serous retinal detachment was also found. This ocular finding was not reported in the previous literature. Although Joubert syndrome has many variable phenotypes and the molecular basis is still unknown, the newly reported ocular features suggest that a different genetic form may be present.

Allelic imbalance at 13q31 is associated with reduced GPC6 in Chinese with sporadic retinoblastoma

BACKGROUND/AIMS

Loss of heterozygosity (LOH) has been discovered in retinoblastoma (RB) in previous studies. In this study, we aimed to discover potential tumour suppressor genes through investigation of the incidence of allelic loss in chromosome 1, 6, 9, 13, 19, 20, 21, 22 and X in Chinese sporadic retinoblastoma patients and to study the expression of genes flanking LOH region 13q31.

METHODS

Twenty-five microdissected RB samples were analysed to investigate the LOH in 140 microsatellite markers. Expression of genes flanking D13S265 was investigated by real-time quantitative-PCR on available frozen samples. The promoter and entire coding region of GPC6 were examined for sequence changes in an extended batch of 29 RB samples.

RESULTS

Allele losses were found in 92% (23/25) of the tumours. We identified a new LOH locus at 13q31 (D13S265) with a high occurrence rate (67%, 14/21) apart from the RB1 locus (68%, 17/25). Expression study detected the reduced expression of Glypican 6 (GPC6) transcript significantly associated with the LOH at 13q31 (p=0.024). Furthermore, mutation screening revealed no remarkable sequence alteration in GPC6 that could affect its expression.

CONCLUSION

Results suggest that a reduction in GPC6 mRNA in retinoblastoma is associated with the non-random allelic loss at 13q31 that could contribute to RB development.

Prenatal screening for retinoblastoma in Hong Kong

We report the first use in Hong Kong of molecular techniques to screen prenatally for retinoblastoma and review 17 cases of retinoblastoma seen at the Hong Kong Eye Hospital from 2001 to 2006. A pregnant couple whose first child had retinoblastoma requested prenatal screening for retinoblastoma during their second pregnancy in 2000. Whole RB1 coding gene sequencing was performed on peripheral blood cells taken from family members and cultured amniocytes collected from the foetus during the 14th week of gestation. No RB1 gene mutations were found in the amniocyte samples and at birth the baby had no evidence of ocular tumours. During 5 years of follow-up the child remained healthy with intact visual function. Prenatal diagnosis of retinoblastoma alleviates parental stress and improves the perinatal care of affected family members.

Anterior segment ischemia after two-muscle surgery in a patient with radiation-treated nasopharyngeal carcinoma

Anterior segment ischemia after strabismus surgery is a rare occurrence. Risk factors include single-stage surgery of three or more muscles in one eye, dysthyroid eye disease, and advanced age. The authors report a case of anterior segment ischemia after single-stage surgery of two horizontal muscles without previous reported risk factors. However, the patient had received radiotherapy for nasopharyngeal carcinoma more than 20 years ago. The case was successfully treated with systemic steroids but with reduced best-corrected visual acuity. Previous radiotherapy in the related orbital field may be a new risk factor for this condition.

Changes in refraction and ocular dimensions after cataract surgery and primary intraocular lens implantation in infants

PURPOSE

To study refraction and axial length changes after cataract extraction and primary intraocular lens (IOL) implantation in children younger than 1 year of age.

SETTING

Two regional hospitals.

METHODS

After determining the IOL power for emmetropia, 80% of the value was used to choose the IOL for implantation to counter anticipated myopic shift with age. The main outcome measures were changes in refraction and axial length 3 years after surgery.

RESULTS

Thirty-four eyes of 20 children (mean age 6.7 months +/- 3.9 [SD]) were studied. Refraction in the immediate postoperative period was +4.53 +/- 1.45 diopters (D). Three years after surgery, the mean refraction was -2.49 +/- 3.08 D (P<.001). Twenty-two eyes (64.7%) had surgery during the first 6 months of life (group 1) and had a shorter axial length at surgery (mean 18.92 +/- 1.32 mm) compared with 12 eyes (35.3%) that received surgery between 7 and 12 months (group 2, mean 20.29 +/- 1.00 mm) (P = .007). However, the final axial length was greater in group 1 (mean 22.67 +/- 1.04 mm) than in group 2 (mean 21.23 +/- 0.26 mm) (P = .019).

CONCLUSIONS

Primary IOL implantation is an option for children having cataract surgery in the first year of life. Significant myopic shifts occurred, and this seemed to be more pronounced in younger children. It appears that rethinking current strategies for IOL power calculation may be required to achieve more optimal refractive outcomes.

Updates on the surgical management of paediatric cataract with primary intraocular lens implantation

With the advent of modern surgical techniques, paediatric cataract has become much more manageable. Intraocular lens (IOL) implantation is the standard of care for patients over the age of 2 years. The use of IOL in young infants is still controversial. In addition, there are still unresolved issues, such as the minimum age at which IOL can be safely implanted, IOL power selection and IOL power calculation. The current trends in the management of the above challenges are discussed. Although numerous reports on the prevention and management of posterior capsule opacification have been published, there are ongoing intensive debates and research. Long-term postoperative complications like glaucoma and rhegmatogenous retinal detachment are problems that cannot be overemphasised and these issues are also reviewed.

Multistage approach to uveitic cataract management in children

Phototherapeutic keratectomy, cataract extraction and hydrophobic acrylic lens implantation, Nd:YAG laser capsulotomy, glaucoma valve implantation, and intravitreal steroid injections resulted in substantial visual improvement in three eyes of two children with complicated cataract due to severe uveitis. At follow-up of 6 months to 4 years, the children had clear corneas and normal intraocular pressures.

25-Gauge transconjunctival sutureless vitrectomy system in the surgical management of children with posterior capsular opacification

PURPOSE

To evaluate the safety and efficacy of the 25-gauge transconjunctival sutureless vitrectomy (TSV) system in the surgical management of posterior capsular opacification (PCO) in pseudophakic children.

METHODS

Pars plana membranectomy was performed for PCO in 10 pseudophakic eyes of six children (mean age 35.1 +/- 37.8 months; range 6-93 months) using the TSV system. Surgical technique, intraoperative problems and postoperative complications including wound leakage, hypotony and the need for suturing were recorded.

RESULTS

Wound leakage and other intraoperative problems were not noted in any of the eyes. All eyes showed improvement of visual acuity from a mean of 6/67 before to 6/29 after surgery (P = 0.001). Mean postoperative intraocular pressure (IOP) was 7.8 +/- 3.1 mmHg (range: 3-10 mmHg). Four eyes (40%) had hypotony on the first postoperative day (IOP: 3-5 mmHg), which was transient in three eyes. One eye in a patient with uveitis had persistent hypotony, but hypotony was also present preoperatively, and the postoperative IOP returned to preoperative levels. This eye also developed recurrent PCO and a second capsulotomy was performed using the 25-gauge TSV system.

CONCLUSIONS

Posterior capsulotomy using the 25-gauge TSV system appears to be a safe and effective approach in the management of PCO in pseudophakic children. Advantages include easier manipulation with the smaller instruments in these small eyes, and it can be considered in appropriate cases.

Ocular hypertensive and anti-inflammatory responses to different dosages of topical dexamethasone in children: a randomized trial

BACKGROUND

The purpose of the present study was to investigate the ocular hypertensive and anti-inflammatory responses to two different dosage schedules of 0.1% topical dexamethasone in a population of Chinese children undergoing strabismus surgery.

METHODS

Children undergoing bilateral strabismus surgeries were randomly assigned to receive topical 0.1% dexamethasone eye drops four times daily (group A) or twice daily (group B) for 4 weeks. Intraocular pressure (IOP) and anti-inflammatory responses were monitored for 8 weeks.

RESULTS

A total of 137 children with mean age 6.5 years (SD, 1.9 years; range, 3-10 years) participated in the study. The IOP increased significantly after 4 weeks in both groups compared to the preoperative values (P < 0.001). Peak IOP ranged from 14.0 to 50.3 mmHg in group A and 11.0-41.3 mmHg in group B. Cases in group A (mean, 13.8 mmHg; SD, 8.4 mmHg) had a greater net increase in IOP than cases in group B (mean, 10.2 mmHg; SD, 6.2 mmHg; P = 0.004). Younger-aged children had higher peak IOP (r = -0.244, P = 0.048), and attained the peak IOP earlier (r = 0.252, P = 0.041) in group A. There was no significant difference in ocular inflammatory response between the two groups.

CONCLUSION

Ocular hypertensive effect to topical 0.1% dexamethasone is dose and age dependent in children. Twice-daily 0.1% topical dexamethasone eye drops control inflammation after strabismus surgery as effectively as four-times-daily dosage, but induces less increase in IOP, and may be a better treatment schedule.

Clinical implications of promoter hypermethylation in RASSF1A and MGMT in retinoblastoma

We investigated the epigenetic silencing and genetic changes of the RAS-associated domain family 1A (RASSF1A) gene and the O6-methylguanine-DNA methyltransferase (MGMT) gene in retinoblastoma. We extracted DNA from microdissected tumor and normal retina tissues of the same patient in 68 retinoblastoma cases. Promoter methylation in RASSF1A and MGMT was analyzed by methylation-specific PCR, RASSF1A sequence alterations in all coding exons by direct DNA sequencing, and RASSF1A expression by RT-PCR. Cell cycle staging was analyzed by flow cytometry. We detected RASSF1A promoter hypermethylation in 82% of retinoblastoma, in tumor tissues only but not in adjacent normal retinal tissue cells. There was no expression of RASSF1A transcripts in all hypermethylated samples, but RASSF1A transcripts were restored after 5-aza-2'-deoxycytidine treatment with no changes in cell cycle or apoptosis. No mutation in the RASSF1A sequence was found. MGMT hypermethylation was present in 15% of the retinoblastoma samples, and the absence of MGMT hypermethylation was associated (P = .002) with retinoblastoma at advanced Reese-Ellsworth tumor stage. Our results revealed a high RASSF1A hypermethylation frequency in retinoblastoma. The correlation of MGMT inactivation by promoter hypermethylation with lower-stage diseases indicated that MGMT hypermethylation provides useful prognostic information. Epigenetic mechanism plays an important role in the progression of retinoblastoma.

Comparative study on the safety and efficacy of different cycloplegic agents in children with darkly pigmented irides

BACKGROUND

The ideal cycloplegic drug that is safe, effective and convenient in children is not yet available. This study aimed to evaluate the safety and efficacy of three cycloplegic regimens in hyperopic children with pigmented irides. The responses to cycloplegia in different age groups and presence of strabismus were also compared.

METHODS

Tropicamide 0.5% and phenylephrine 0.5% (regimen I), tropicamide 1.0% and cyclopentolate 1.0% (regimen II), and atropine 1.0% (regimen III) were evaluated in 25 children using a crossover study design. Cycloplegic refractions were assessed.

RESULTS

The mean age of the children was 5.7 +/- 2.0 years (range 2.5-10.8 years). Six (24.0%) of them had strabismus. The spherical equivalent (SE) refraction for regimens I, II and III were +5.11 +/- 2.04 D, +5.29 +/- 1.89 D and +5.71 +/- 1.90 D, respectively, and were significant different from the manifest SE (+3.95 +/- 2.17 D) (P < 0.001). There was no statistical difference between regimen I and II in children without strabismus (P = 0.258) or aged older than 5 years (P > 0.050).

CONCLUSION

In older children, regimen I was as effective as regimen II and can be used to avoid cyclopentolate toxicity.

Microsatellite instability and MLH1 promoter methylation in human retinoblastoma

PURPOSE

To investigate the link between microsatellite instability and epigenetic silencing of the MLH1 gene in the human retinoblastoma genome.

METHODS

Methylation at the 5' region of MLH1 was studied, along with its protein expression level by using immunohistochemical staining in 51 retinoblastoma tumors and 2 retinoblastoma cell lines. Also assessed was the genomic stability of 26 retinoblastoma DNAs from microdissected tumor tissue and matched normal retina tissue obtained from the same patient by microsatellite instability (MSI) analysis. The National Cancer Institute-designed reference panel, and 85 markers on chromosomes 1, 6, 9, and 13 were used.

RESULTS

Hypermethylation of the MLH1 promoter was detected in the WERI-Rb1 cell line and in 34 (67%) of the 51 tumors, but not in cell line Y79 and the other 17 tumors. MLH1 hypermethylation was associated with null MLH1 protein expression (P < 0.0005) and with well-differentiated histology (P < 0.05). MSI at three markers (D2S123, D6S470, and D13S265) was frequently identified among 26 retinoblastoma specimens with matched normal DNA. Among these 26 retinoblastomas, high-frequency MSI (MSI-H) tumors were detected in 19% (5/26) and low-frequency MSI (MSI-L) in another 19% (5/26). The remaining 62% (15/26) were genetically stable (MSS). MSI status (MSS, MSI-L, and MSI-H) was not associated with MLH1 promoter hypermethylation (P = 0.088; Kruskal-Wallis test).

CONCLUSIONS

Epigenetic silencing of the DNA repair gene MLH1 by promoter hypermethylation is a frequent event in retinoblastoma. The results showed that somatic genetic changes involving MSI occur in a subset of retinoblastoma and implicated the presence of a defective DNA mismatch repair pathway resulting in MSI in retinoblastoma.

Ocular-Hypertensive and Anti-inflammatory Response to Rimexolone Therapy in Children

OBJECTIVE

To compare the ocular-hypertensive and anti-inflammatory response to rimexolone (116-hydroxy-16alphafluoro-6alphamethylpresdnisolone) and fluorometholone (21-deoxy-9alphafluoro-6alphamethylprednisolone) therapy in children's eyes.

METHODS

With parental consent, children who underwent surgical procedures for bilateral symmetric strabismus from January 18, 2000, through November 16, 2001, were recruited. One eye was randomized to receive topical 1% rimexolone while the contralateral eye received topical 0.1% fluorometholone, 4 times daily for 4 weeks.

MAIN OUTCOME MEASURES

Intraocular pressures and anti-inflammatory responses were the main outcome measures and were serially measured postoperatively for 8 weeks.

RESULTS

Fifty-four children, aged from 4 to 8 years (mean [SD] age, 5.33 [1.26] years), participated in the study. Intraocular pressure increased significantly in both treatment groups compared with the preoperative values (P<.001). The mean (SD) peak intraocular pressure was significantly higher in the rimexolone-treated group, 19.7 (6.1) vs 17.6 (4.6) mm Hg (P<.001). Similarly, the mean (SD) net increase in intraocular pressure (P<.001), was also higher in the rimexolone-treated eyes, 5.9 (4.4) vs 3.9 (4.1) mm Hg (P<.001). In addition, a greater percentage of the rimexolone-treated patients had no conjunctival erythema on days 13 (11.1% vs 0.0%) and 20 (88.9% vs 55.6%) (P =.03).

CONCLUSIONS

Rimexolone seems to be a more effective anti-inflammatory agent than fluorometholone. However, unlike adults, the ocular-hypertensive effect in children treated with rimexolone was higher. It would be desirable to monitor the intraocular pressure regularly when rimexolone therapy is used in children.

Topical mydriatic and cycloplegic spray for Chinese children

PURPOSE

To assess the efficacy and tolerance of mydriatic and cycloplegic spray versus drops for Chinese children.

METHODS

The effects of the spray (cyclopentolate 0.25%, phenylephrine 0.625%, and tropicamide 0.5%) and the drops (cyclopentolate 1%, phenylephrine 0.5%, and tropicamide 0.5%) were evaluated in 29 children (58 eyes) in two separate sessions. There was a 1-week period between the applications of the spray and the drops. Dilated pupil size and refraction after cycloplegia were the primary outcome variables used to assess the efficacy. A subjective discomfort score was used to assess acceptance of the spray and the drops.

RESULTS

The mean age of the study population was 4.33 +/- 1.39 years (range, 3 to 8 years). The mean pupil size was 6.9 mm for the spray and 6.6 mm for the drops. The spray appeared to be slightly more effective than the drops, with a mean difference of 0.3 mm that was statistically significant (P = .001, two-tailed t test). No statistically significant difference in cycloplegic response was found between the spray and the drops (P = .535, two-tailed t test). Administration of the spray caused less discomfort than did administration of the drops (P < .001, Wilcoxon signed-rank test).

CONCLUSIONS

The spray system appears to be clinically equivalent to the drops for achieving effective pupil dilation and cycloplegia, even in a population with dark irides such as ours. Tolerability and acceptance improved because the spray was applied to the closed eyelids.

Isolated microspherophakia with optic disc colobomata

We describe a case of isolated bilateral microspherophakia with optic disc colobomata. A satisfactory outcome was achieved following uneventful lensectomy and scleral fixation of an intraocular lens.

Comparison of lidocaine 2% gel versus amethocaine as the sole anesthetic agent for strabismus surgery

PURPOSE

To compare the efficacy of lidocaine 2% gel with amethocaine 1% eyedrops as the sole anesthetic agent for one-stage adjustable suture strabismus surgery.

DESIGN

Prospective, double-masked randomized trial.

PARTICIPANTS

Fourteen consecutive patients scheduled to undergo bilateral and symmetrical strabismus surgery under topical anesthesia in one institution.

METHODS

Each patient was randomized to receive lidocaine 2% gel in one eye and amethocaine 1% eyedrops in the other eye as the sole anesthetic agent for surgery. Masking of the patient and surgeon was ensured by administration of a placebo gel and eyedrop as part of the regimen. Pain and discomfort were assessed via a 10-cm visual analog scale.

MAIN OUTCOME MEASURES

Subjective pain and discomfort perceived during surgery were assessed separately by the patient and the surgeon, and the need for any additional anesthesia was recorded.

RESULTS

A total of 14 subjects indicated mean pain and discomfort scores of 2.6 and 3.2 respectively, for lidocaine gel, and 5.3 and 6.2, respectively, for amethocaine drops (P = 0.01). The mean number of additional drops required by eyes randomized to lidocaine gel was 0.3, compared with 1.6 for amethocaine drops (P = 0.02).

CONCLUSIONS

In terms of pain control, lidocaine 2% gel alone is a superior topical anesthetic for one-stage adjustable suture strabismus surgery when compared with amethocaine 1% eyedrops.

Loss of heterozygosity and mutations are the major mechanisms of RB1 gene inactivation in Chinese with sporadic retinoblastoma

We investigated sequence alternation, promoter methylation, and loss of heterozygosity (LOH) of the RB1 gene as possible mechanisms of its inactivation in retinoblastoma. In 42 Chinese patients with sporadic retinoblastoma, the promoter and entire coding region of RB1 were examined for sequence changes. Status of methylation of the CpG-rich island at the 5'end was determined by methylation specific PCR assay. We detected 15 RB1 mutations in 38% (16/42) of the retinoblastoma patients, among them 19% (8/42) were germ-line mutations. A total of nine novel mutations were identified: E54X, S114X, I126S, g73779insG, D718N, IVS2+1G>C, IVS14+1G>C, IVS21+1G>C, and a complex alteration g78177G>T/g78176insTT leading to 543X. Most of them are likely to affect the RB1large pocket domain through the production of truncated gene products. None of the DNA samples showed methylation at the RB1promoter. In 15 cases where both normal and cancerous retinoblastoma tissue specimens were available, allelic loss according to microsatellite markers within or distal to the RB1 locus was analyzed and immunohistological staining for RB1 expression performed. Among them, frequency of LOH at 13q14 was found to be high at 60% (9/15) with no segregation with unilateral tumors. All these nine tumors did not express RB1 protein, showing an association of LOH at the RB1 locus with its loss of expression in retinoblastoma. Our results indicate that the RB1 gene in sporadic retinoblastoma is commonly inactivated because of loss-of-function mutations and loss of heterozygosity but not by the epigenetic phenomenon of promoter hypermethylation.

Changing patterns of strabismus: a decade of experience in Hong Kong

BACKGROUND/AIMS

Racial variation in the pattern of strabismus is known, but few large scale studies on non-white populations are available. Furthermore, longitudinal change in this pattern within a local setting has not been well documented in the past. This study aims to support the clinical impression that exotropia is more common in Chinese patients, and that the proportion of patients with exotropia has been increasing in the past decade.

METHODS

A total of 2704 consecutive patients with the diagnosis of primary horizontal strabismus, seen in the strabismus clinic of the Hong Kong Eye Hospital, were retrospectively analysed to determine the relative prevalence of esotropia and exotropia. Characteristics recorded include patient demographics, type of strabismus, and whether the nature of the squint was constant or intermittent.

RESULTS

742 (27.4%) patients were found to have esotropia, 548 (20.3%) had constant exotropia, 1213 (44.9%) had intermittent exotropia, and 201 (7.4%) had microtropia. The proportion of exotropic to esotropic patients was shown to increase steadily throughout the past decade (p<0.0001). This was mainly accounted for by an increase in the number of patients with intermittent exotropia, and a corresponding decrease in the number of patients with esotropia.

CONCLUSION

Exotropia was shown to be more prevalent than esotropia in a Hong Kong Chinese population. Furthermore, the proportion of patients with intermittent exotropia appears to be increasing, in contrast with esotropic patients. The exact nature of this trend, and possible aetiological factors will require further study.

Impaired expression and promotor hypermethylation of O6-methylguanine-DNA methyltransferase in retinoblastoma tissues

PURPOSE

To investigate the role of epigenetic changes in the promoter region of tumor-suppressor genes in the retinoblastoma genome and to study the disruption of expression of O6-methylguanine-DNA Methyltransferase (MGMT) due to aberrant methylation and its association with retinoblastoma.

METHODS

A series of 23 retinoblastoma tissue specimens and 2 retinoblastoma cell lines (Y79 and WERI-Rb1) were subjected to methylation-specific PCR (MSP) analysis of hypermethylated genes identified in human cancers, including p14(ARF), p15(INK4b), p16(INK4a), VHL, and MGMT. Further, the expression of MGMT was studied by immunohistochemistry and, when fresh tissue was available, by Western blot analysis and RT-PCR.

RESULTS

Aberrant methylation of at least one MGMT locus was detected in 8 of the 23 tumors (35%), all of which (100%) had impaired or absent expression of MGMT. The remaining 15 tumor specimens were nonmethylated, and, among them, 7 (43%) showed defective expression. No methylation of tumor DNA was found on the p14(ARF), p15(INK4b), p16(INK4a), and VHL genes. Hypermethylation in the MGMT promoter was found to be prominently present in retinoblastoma with poor tissue differentiation, and was more frequently detected among patients with bilateral disease. Production of MGMT was consistent with expression of mRNA. No methylation of MGMT promoter was detected in the two retinoblastoma cell lines (Y79, WERI-Rb1).

CONCLUSIONS

The data show a clear association between impaired production of MGMT and hypermethylation of the MGMT promoter, which appeared to relate to early onset and poor differentiation, suggesting that epigenetic silencing of MGMT by methylation of the promoter and reduced expression of MGMT may play an important role in the development and progression of retinoblastoma.