Ricky W.K. Law

Analysis of the Posterior Polymorphous Corneal Dystrophy 3 Gene, TCF8, in Late-Onset Fuchs Endothelial Corneal Dystrophy

PURPOSEnBecause the endothelial (posterior) corneal dystrophies share common pathologic features and result from primary endothelial dysfunction, it is possible that a proportion of them could be clinical manifestations of different mutations of the same gene. The aim of our study was to determine whether mutations of the TCF8 gene, recently implicated in posterior polymorphous dystrophy, may also play a role in the development of the more common Fuchs endothelial corneal dystrophy (FECD).nnnMETHODSnGenomic DNA was extracted from leukocytes of peripheral blood, and the nine exons of the TCF8 gene were PCR amplified and subjected to bidirectional sequencing and analysis. Samples from 74 unrelated Chinese patients (55 women, 19 men) with a diagnosis of late-onset FECD and 93 age- and race-matched controls were studied.nnnRESULTSnThe affected probands ranged in age from 52 to 91 years (mean age, 65.1 years); 8 had familial FECD and 66 had sporadic FECD. The authors found two mutations in the coding region of the TCF8 gene: a novel missense mutation in one patient c.2087A>G in exon 7 (Asn696Ser) and a silent mutation in exon 2 c.192T>C (D64D).nnnCONCLUSIONSnThe identification of a novel missense mutation in only one of the patients implied that TCF8 does not play a significant role in the pathogenesis of FECD in this Chinese population.

Phacoemulsification, primary posterior capsulorhexis, and capsular intraocular lens implantation for uveitic cataract

Purpose: To evaluate the safety and efficacy of phacoemulsification, primary posterior capsulorhexis (PCCC), and primary intraocular lens (IOL) implantation for uveitic cataracts. Setting: Institutional practice. Methods: Fifteen consecutive eyes of 13 patients with various causes of uveitis received anterior capsulorhexis, phacoemulsification, PCCC, and in‐the‐bag implantation of a heparin‐surface‐modified IOL for visually disabling cataract. The safety and efficacy of the combined operation were studied prospectively. Results: At a mean follow‐up of 16.9 months (range 8 to 30 months), all eyes had a clear central visual area. Fourteen of 15 eyes (93.3%) had good visual improvement after surgery. Eight eyes (53%) achieved a best corrected visual acuity (BCVA) of 20/30 or better and 6 (40%), 20/20 or better. Seventy‐three percent of eyes attained a BCVA of 20/80 or better. The mean improvement in visual acuity was 5.2 Snellen lines (range 0 to 11 lines). No cases of uveitis flare‐up or other major complications related to the cataract surgery occurred. Conclusions: The study’s preliminary results are encouraging and indicate that phacoemulsification, PCCC, and IOL implantation can be considered in patients with visually disabling uveitic cataract.

Confocal microscopy of posterior polymorphous endothelial dystrophy

Purpose: To report the in vivo confocal microscopic findings of posterior polymorphous endothelial dystrophy (PPED). Methods: Four patients with PPED from 2 unrelated families and 2 asymptomatic children of an index patient were included in this observational case series. The eyes of the 6 subjects were examined by confocal light microscopy. Results: Confocal microscopy demonstrated craters, streaks, and cracks over the corneal endothelium surface. Pleomorphism and polymegathism were present in eyes with PPED. Guttae and clusters of abnormal endothelial cells were also identified in corneas of these PPED patients. These findings were absent in eyes without clinical manifestations of PPED. Conclusions: In vivo confocal microscopy is potentially useful for excluding suspected cases of subclinical PPED. Abnormalities in the Descemet membrane and endothelium were observed.

Efficacy of lignocaine 2% gel in chalazion surgery

Background/aims: To determine whether topical 2% lignocaine (lidocaine) gel is an effective anaesthetic agent for chalazion surgery. Methods: In a randomised controlled clinical trial, 57 subjects aged 12 years or over requiring incision and curettage for chalazion were recruited over an 8 month period. Patients were randomised into two groups. One group received 1.5 ml of lignocaine 2% injection and the other 1.5 ml of lignocaine 2% gel topically. Standard incision and curettage was then performed. The primary outcome of interest was the total pain experienced during the entire procedure including anaesthetic administration as well as incision and curettage. The pain from the local anaesthetic administration and during incision and curettage was assessed independently using a visual analogue scale (0–100). The sum of these two scores would be the total pain score out of 200. “Fear of injection” score (0–100) was also assessed. Results: There was a statistically significant difference in the mean total pain scores between the injection and the gel groups (95.6 v 57.0) (p <0.001) (α = 0.05) (1 − β = 0.9394). There was a statistically significant difference in the mean scores on “pain of anaesthetic administration” (47.0 v 5.5) (p <0.000). There was no statistically significant differences in the mean scores on “fear of injection” (43.9 v 47.7) (p = 0.668) and “pain during incision and curettage” (48.28 v 51.4) (p=0.679). Conclusions: Lignocaine 2% gel is effective in chalazion surgery especially in lowering the pain caused by anaesthetic administration.

Bilateral peripheral corneal infiltrates after simultaneous myopic laser in situ keratomileusis.

We describe a patient with multiple superior corneal infiltrates in both eyes, separated from the limbus by an intervening clear zone, that appeared 1 day after uneventful laser in situ keratomileusis. The overlying epithelium was intact, and the flap and interface were uninvolved. Based on these features, a clinical diagnosis of sterile corneal infiltrates was made and the eyes were treated with topical antibiotics and steroids. The infiltrates resolved during the ensuing weeks without corneal scarring. Good visual acuity was maintained. Recognition of this benign complication is important because aggressive corneal scrapings are not required. The infiltrates appear to be immunogenic in origin, although the exact etiopathogenesis is not clear.

Prospective randomized double-masked trial to evaluate perioperative pain profile in different stages of simultaneous bilateral LASIK.

Purpose: To evaluate the perioperative pain profile in simultaneous bilateral LASIK. Methods: Fifty consecutive Chinese patients undergoing simultaneous bilateral LASIK were randomly allocated to have either the right or left eye operated first. The pain scores for each eye at speculum placement, microkeratome cut, laser ablation, and at 15, 30, and 45 minutes after the procedure were recorded. In addition, an overall score for the whole operation was evaluated immediately after the procedure for each eye. Comparisons between eyes and among different stages of the procedures were analyzed. Results: The second eye was significantly more painful than the first eye at the stage of speculum placement and microkeratome pass (P < 0.001). Laser ablation was the least painful stage for both eyes. There were no statistical differences in pain scores for the postoperative period. Conclusion: Higher pain scores were associated with the stages involving eyelid manipulation. In patients with small palpebral fissures where stretching of the eyelid structures are anticipated, supplementary anesthesia for the lid region should be considered when required.

In vivo confocal microscopy of epithelial inclusions from aberrant wound healing after astigmatic keratotomy.

Objective: To report confocal microscopic findings in vivo of delayed prominent epithelial inclusions at a gaped incision groove after astigmatic keratotomy (AK). Methods: Astigmatic keratotomy using paired arcuate incisions was performed on the right eye of a 59-year-old man who had a preoperative refraction of +2.50 DS, −7.00 DC × 80. The procedure and initial postoperative course were uneventful, and his refraction was OD +1.00 DS, −2.50 DC × 60 at 16 months. However, at 17 months postsurgery, tiny pearl-like lesions appeared along one of the incision grooves. In vivo confocal microscopy was performed to investigate these lesions. Results: Under confocal microscopy, clusters of epithelial inclusions inside the gaped incision groove corresponded to the pearl-like lesions observed clinically. A confluent layer of flat, regular and polygonal epithelial cells covered the wall of the groove. Activated keratocytes were observed adjacently. The number of keratocytes around the groove, however, did not appear to increase in comparison to normal corneal wound healing and scar formation. No foreign body, infective, or inflammatory signs were observed. Conclusions: Aberrant wound healing was identified in post-AK incisions, similar to post–radial keratotomy cases. Confocal microscopy is a useful tool to study the wound healing of AK incisions and to rule out foreign bodies or infective elements as illustrated by this case. To the best of our knowledge, this is the first reported in vivo confocal study of AK wound healing in humans.

Association of Transcription Factor 4 (TCF4) and Protein Tyrosine Phosphatase, Receptor Type G (PTPRG) with Corneal Dystrophies in Southern Chinese

Abstract Fuchs’ endothelial dystrophy is a common type of posterior CD characterized by the development of gutta in the Descemet membrane. Recently, TCF4 was considered as a major risk gene for European FED cases. However, another recent report has shown that rs613872 was not associated with Singaporean Chinese FEDs. Recent reports indicate the genotypic heterogeneity of FEDs in different ethnic populations. It is thus essential to understand whether these genes affect the occurrence of FEDs and non-Fuchs’ CD in the local population. In the present study, we screened several reported SNPs (rs2286812, rs17595731 and rs613827 in TCF4; rs7640737 and rs2292245 in PTPRG) in FED and non-Fuchs’ patients with corneal dystrophies of southern Chinese.

Randomized Double-Masked Controlled Trial Comparing Pain Scores With and Without the Use of Supplementary 2% Lidocaine Gel in LASIK

PURPOSEnTo compare pain scores with and without supplementary topical 2% lidocaine gel in patients undergoing simultaneous bilateral laser-assisted in situ keratomileusis (LASIK) under topical anesthesia using 0.5% proparacaine eye drops.nnnDESIGNnRandomized double-masked placebo-controlled trial.nnnMETHODSnFifty-one Chinese subjects (102 eyes, with 51 eyes in each arm) were included. One eye was randomly allocated to have supplementary 2% lidocaine gel while the other eye received carbomer gel as control, in addition to topical 0.5% proparacaine. The pain scores for each eye during microkeratome flap creation, during laser ablation, and at 15, 30, and 45 minutes after LASIK were assessed. An overall pain score of the LASIK procedure was also obtained. Primary outcome measures were pain scores during and after LASIK. Secondary outcomes included need for additional topical anesthesia, patient cooperation score, and duration and complications of surgery.nnnRESULTSnIn the 2% lidocaine gel-treated group, the pain scores were significantly lower during microkeratome flap creation and laser ablation, and postoperatively at 30 and 45 minutes (P<.05 for all). Patients in the lidocaine gel group required less additional topical anesthesia (P=.0004) and were more cooperative (P=.019) as compared to the carbomer gel group. No surgical or postoperative complications were observed.nnnCONCLUSIONSnThe use of supplementary 2% lidocaine gel in LASIK is effective in lowering the pain experienced during and up to 45 minutes after LASIK.

Reproducibility of corneal flap thickness in laser in situ keratomileusis using the hansatome microkeratome

regarding the inconsistency of the Hansatome in achieving constant flap thickness. This study points out that despite the intended thickness of 180 m, the calculated flap thickness was only 120.87 m 26.39 (SD). In other words, over 98% of the flaps were undercut assuming a normal distribution. Reviewing recent literature, it seems that undercutting is common even when different microkeratomes are used. Using the Automated Corneal Shaper (ChironAdatomed), Behrens et al. show that the mean flap central thickness is 125.00 32.00 m with a 160 m footplate. This represents a 95% undercutting rate. Using the SCMD manual microkeratome (United Development Corp.), Yi and Joo show a mean flap central thickness of 137.18 33.66 m with a 150 m footplate, which indicates at least a 50% undercutting rate. If the inconsistency of flap thickness were due to normal variation in the performance of the microkeratome, one would expect an equal distribution of overcutting and undercutting, with the mean very close to the expected value. The fact that there is more undercutting may imply that inconsistent flap thickness is multifactorial. Since flap thickness is calculated by subtracting the preoperative pachymetry from the intraoperative stromal thickness, any apparent increase in stromal thickness can transfer to an underestimation of flap thickness. Intraocular pressure (IOP) has been shown to affect intraoperative flap thickness. It is therefore possible that when vacuum is built up during suction, the high IOP causes localized stromal edema that, in turn, increases stromal bed thickness. The calculated flap thickness will therefore be lower than expected. We believe that further studies with direct measurement of the flap thickness are important in evaluating actual flap thickness and the causal relationship between flap thickness and the microkeratome design.