Arthur S. M. Lim

Myopia in Singapore: taking a public health approach

Myopia is a problem of public health concern in Singapore for three reasons. Firstly, the prevalence of myopia (more than −0.5 dioptres (D)) is one of the highest worldwide. Twenty per cent of Singapore children are myopic at 7 years at the start of their primary education,1 with prevalence exceeding 70% upon completing college education.2-4 Other population based studies showed myopia prevalence of 15% in preschool 4 year old children,5 80% in military conscripts,6 and nearly 40% in adult Chinese aged 40 and older.7 This is 1.5–3 times higher than similarly aged white or black populations in the United States,8-10 and elsewhere.1112 Secondly, a large proportion of Singaporeans has high myopia (more than −6.0 D), which has been observed across the whole age spectrum.167 While the prevalence of high myopia is less than 2% in most Western populations,1011approximately 10% of Singapore adults have the condition.67 Thirdly, available data suggest that both prevalence and severity of myopia have increased significantly over the past two decades. Based on serial cross sectional data from the Singapore Armed Forces, myopia prevalence in military conscripts has increased from 26% in the late 1970s, to 43% in the 1980s, 66% in the mid 1990s, and 83% by the late 1990s.61314 This is accompanied by a twofold rise in the proportion with myopia worse than −8 D, from 2% to 4% between 1993 and 1997.4 A similar trend of increasing myopia prevalence has been observed in schoolchildren.115 The underlying explanation for high myopia prevalence and severity in Singapore is not well understood. Available data suggest that this phenomenon is not unique to Singapore. A high prevalence of myopia has also been described in other east …

Randomized clinical trial of a new dexamethasone delivery system (surodex) for treatment of post-cataract surgery inflammation

OBJECTIVE To evaluate the safety of Surodex Drug Delivery System (Oculex Pharmaceuticals, Inc., Sunnyvale, CA) containing dexamethasone 60 micrograms, for use in cataract surgery, and to compare its anti-inflammatory efficacy with conventional dexamethasone 0.1% eyedrops. DESIGN Randomized, masked, and partially controlled trial. PARTICIPANTS Sixty eyes of 60 Asian patients undergoing extracapsular cataract extraction with intraocular lens implantation were examined. Of these, 28 eyes of 28 patients served as control eyes. Patients were stratified for age and presence of diabetes mellitus. INTERVENTION Surodex was inserted in the anterior chamber of 32 eyes at the conclusion of surgery. These eyes received placebo eyedrops four times a day after surgery for 4 weeks. Control eyes received neither Surodex nor a placebo implant but were prescribed conventional 0.1% dexamethasone eyedrops four times a day for 4 weeks. MAIN OUTCOME MEASURES Anterior chamber cells and flare were clinically graded at the slit lamp. Anterior chamber flare was objectively assessed with the Kowa FM500 Laser Flare Meter (Kowa Co. Ltd, Tokyo, Japan) for up to 3 months after surgery. Intraocular pressure and corneal endothelial specular microscopy with morphometric cell analysis were performed for up to 1 year after surgery. RESULTS Clinical slit-lamp assessment of anterior chamber flare and cells showed no difference between Surodex-treated eyes and dexamethasone eyedrop-treated eyes. Flare meter readings showed lower flare levels in the Surodex group at all postoperative visits compared with the dexamethasone eyedrop group. Flare reduction in the Surodex group reached statistical significance at days 4, 8, 15, and 30 after surgery. At 3 months, flare was reduced to preoperative levels in the Surodex group but was still raised in the dexamethasone eyedrop group. Five eyes in the dexamethasone eyedrop group required augmentation of steroids and were deemed therapeutic failures as opposed to one eye in the Surodex group. One patient in the dexamethasone eyedrop group developed postoperative open-angle glaucoma with profound visual field loss and optic disc cupping, resulting in hand movements vision. No significant difference in endothelial cell loss was noted between Surodex-inserted eyes and dexamethasone eyedrop-treated eyes for up to 1 year after surgery. CONCLUSIONS Intraocular placement of a single Surodex is a safe and effective treatment method to reduce intraocular inflammation after cataract surgery. There was no statistical difference in efficacy between Surodex and 0.1% dexamethasone eyedrops in reducing intraocular inflammation, as measured by clinical methods, while Surodex was clearly superior to eyedrops in reducing aqueous flare as objectively assessed with the laser flare meter.

Abnormal Expression of the p53 Tumor Suppressor Gene in the Conjunctiva of Patients With Pterygium

PURPOSE To determine whether pterygium is a disorder of abnormal growth by examining the expression of the p53 gene in the conjunctiva of patients with pterygium. METHODS Immunostaining for abnormal expression of p53 was performed using mouse monoclonal antibody to human p53, pAb 240, on six eyes with primary pterygium and two eyes with recurrent pterygium. RESULTS In three of the eight eyes with pterygium, specimens were positive for abnormal expression in the epithelium of the pterygium and in the superior bulbar conjunctiva. CONCLUSION Abnormal p53 expression in the epithelium of primary and recurrent pterygium specimens suggests that pterygium is a growth disorder rather than a degeneration.

A pilot study of lens extraction in the management of acute primary angle-closure glaucoma.

PURPOSE To describe a pilot study of lens extraction in the management of acute primary angle-closure glaucoma (APACG) in Chinese patients. DESIGN Interventional case series. METHODS A prospective case series of patients presented with APACG at a tertiary eye hospital in Xiamen, China. All the patients had intensive medical treatment followed by immediate phacoemulsification and posterior chamber intraocular lens implantation under topical anesthesia. RESULTS There were 18 patients who were seen with APACG who had phacoemulsification and posterior chamber intraocular lens implantation under topical anesthesia. There was a 9.0-mm Hg drop in mean preoperative and first day postoperative intraocular pressure (22.8 vs 13.8 mm Hg, P =.012) and a 10.2-mm Hg drop in mean preoperative and seventh-day postoperative intraocular pressure (22.8 vs 13.2 mm Hg, P =.002). CONCLUSIONS This pilot study indicates that phacoemulsification and posterior chamber intraocular lens implantation may be useful in the treatment of primary acute angle-closure glaucoma in Chinese patients. Further study with longer follow-up is needed.

Laser iridoplasty in the treatment of severe acute angle closure glaucoma

Twenty eyes of 19 patients presenting with acute angle closure glaucoma (AACG) which failed to respond to medical treatment were treated with laser iridoplasty. In all 20 eyes, laser peripheral iridectomy (PI) was prevented by a hazy cornea. In all cases, iridoplasty resulted in a rapid and significant reduction in intraocular pressure. Laser iridoplasty appears to have a useful role in the management of medically unresponsive AACG, particularly in those cases where laser peripheral iridotomy (PI) has failed or is not possible to perform.

Primary posterior chamber IOL implantation in penetrating ocular trauma

This paper describes the experience of primary cataract extraction and posterior chamber IOL implantation in 11 eyes with penetrating ocular trauma. The primary surgical procedure consisted of repair of corneoscleral laceration, cataract extraction, posterior chamber IOL implantation and in certain cases, removal of intraocular foreign body and vitrectomy. 10 out Of 11 cases had a post operative visual acuity of 6/18 or better, with 9 out of 11 having a post operative visual acuity of 6/12 or better. One case initially had a visual acuity of 6/24 but later developed retinal detachment with a visual acuity of ‘hand movements’. Another patient developed a small localised retinal detachment during the tenth postoperative month but with successful surgery, attained a visual acuity of 6/6. The encouraging results suggest that this procedure may be recommended in carefully selected cases, under the management of an experienced surgeon.

Posterior chamber intraocular lenses in diabetics

This is a study of 63 cases of posterior chamber intraocular lenses implanted in diabetics, with and without retinopathy, undertaken in 1984. 53 (84%) out of the 63 eyes obtained 6/12 or better vision. Excluding preexisting diseases, 52 (95%) out of 55 obtained 6/12 or better vision. Argon laser therapy was performed in 11 patients post-operatively with no difficulties.

Decentered ablation zones resulting from photorefractive keratectomy with an erodible mask

Four patients underwent photorefractive keratectomy for compound myopic astigmatism using the erodible mask. All achieved improvements in unaided visual acuities despite manifesting varying levels of decentration of the ablated zones. However, one patient had significant monocular diplopia because of the severity of the decentration. The problems with the present system include the use of a NON coaxial microscope; difficulty with obtaining and maintaining proper alignment of the excimer laser beam to the erodible mask and the central corneal zone; the inability to interrupt and restart the procedure due to the ablation of the reference marks on the mask; and patient discomfort. We suggest installation of the PMMA mask at the laser aperture in order to alleviate the above difficulties. In the meantime, use of a coaxial microscope, a limbal suction device for fixation, permanent reference marks on the mask and peribulbar anaesthesia may be helpful.

Hypopyon--an unusual sign in acute angle-closure glaucoma.

The appearance of a hypopyon is an extremely uncommon finding in acute angle-closure glaucoma and only a few cases have been previously reported in the literature. We report a fifty-year-old female who, following a recent bereavement, presented with classical features of acute angle-closure glaucoma and a hypopyon. The eye developed a glaukomflecken and the patient underwent trabeculectomy, extracapsular cataract extraction and intraocular lens implantation with good post-operative results. Because hypopyon in acute angle-closure glaucoma is rare and may cause diagnostic confusion and hence therapeutic difficulties, this case is described to highlight this unusual clinical sign.

Local anaesthesia in ophthalmology

The trend for local anaesthesia has grown stronger in the past decade, as ambulatory surgery becomes more widespread, and increasingly older, frailer patients are undergoing surgery. Present-day cataract surgery, using microsurgical suturing techniques, no longer requires prolonged bed-rest. Several factors are essential in successful local anaesthesia in cataract surgery: topical anaesthetic agents; lighter sedation adequate facial akinesia; safe and effective retrobulbar or peribulbar injection and digital pressure to decrease intraocular pressure. Complications of retrobulbar and peribulbar injection, although uncommon, can range from inconvenient retrobulbar haemorrhage to life-threatening respiratory or cardiovascular arrest. Successful high precision microsurgery requires absolute control with proper akinesia and anaesthesia of the eye. The anaesthetist is required to work as part of the team and it is essential that he appreciates the current surgical requirements. In the past decade there have been dramatic changes in ophthalmic surgery. One of the trends is the preference for local anaesthesia.’ More recently, ambulatory (also known as day or outpatient) surgery requires that general sedation should be kept light so that patient can return home the same day. Many ophthalmologists still need the skills of an anaesthetist during surgery so that they can devote their undivided attention to the operating procedure. Anaesthetists working with ophthalmic surgeons should therefore understand and keep abreast of these important developments.