Desmond Quek

Confirmation of the presence of uveal effusion in Asian eyes with primary angle closure glaucoma: an ultrasound biomicroscopy study.

OBJECTIVE To confirm the presence of uveal effusion in the eyes of Asian patients with primary angle closure glaucoma (PACG) using ultrasound biomicroscopy (UBM). METHODS In this observational case series, 70 patients with PACG (28 untreated patients with newly diagnosed PACG and 42 patients who had undergone previous laser iridotomy and were being monitored) and 12 patients with acute primary angle closure (APAC) were recruited. Eyes of patients with newly diagnosed PACG and APAC underwent UBM before and after laser iridotomy, whereas eyes of patients with treated PACG underwent UBM at enrollment. Uveal effusion was defined as a clear space between the choroid and sclera and was graded as follows: grade 0, none; grade 1, slitlike; grade 2, bandlike; and grade 3, obvious. RESULTS Overall, uveal effusion was found in 11 of 70 eyes with PACG (15.7%; 95% confidence interval, 8.8%-26.2%) and in 3 of 12 eyes with APAC (25%; 95% confidence interval, 8.0%-53.4%). For patients with newly diagnosed PACG, uveal effusion was found in 4 of 28 eyes (14.2%; 95% confidence interval, 5.1%-32.1%) before laser iridotomy; 2 eyes had effusion after laser iridotomy. When present, the effusion was grade 1 in PACG eyes and grade 2 or 3 in APAC eyes. CONCLUSIONS Uveal effusion was present in a significant proportion of Asian eyes with PACG and APAC, confirming a recent report of this finding.

Plateau Iris in Asian Subjects With Primary Angle Closure Glaucoma

OBJECTIVE To determine the prevalence of plateau iris in Asian eyes with primary angle closure glaucoma (PACG) using ultrasound biomicroscopy (UBM). METHODS In this cross-sectional observational study, subjects older than 40 years with PACG who had a patent laser peripheral iridotomy underwent UBM in 1 eye. Ultrasound biomicroscopy images were qualitatively analyzed using standardized criteria. Plateau iris in a quadrant was defined by anteriorly directed ciliary body, absent ciliary sulcus, steep iris root from its point of insertion followed by a downward angulation, flat iris plane, and irido-angle contact. At least 2 quadrants had to fulfill these UBM criteria for an eye to be classified as having plateau iris. RESULTS One hundred eleven subjects (70 from Singapore, 41 from Thailand) with PACG were recruited. The mean (SD) age was 65.6 (8.1) years, and 63.9% were female. Based on standardized UBM criteria, plateau iris was found in 36 of 111 eyes (32.4%; 95% confidence interval, 24.4%-41.6%). In these 36 eyes, quadrant-wise analysis showed 66.7% had plateau iris in 2 quadrants; 22.2%, in 3 quadrants; and 11.1%, in all quadrants. CONCLUSIONS About 30% of PACG eyes with a patent laser peripheral iridotomy were found to have plateau iris on UBM, highlighting the importance of non-pupil block mechanisms in Asian individuals.

Blindness and long-term progression of visual field defects in Chinese patients with primary angle-closure glaucoma.

PURPOSE To investigate the long-term rates of blindness and visual field (VF) progression in treated primary angle-closure glaucoma (PACG) patients. DESIGN Retrospective observational case series. METHODS PACG patients with ≥10 years of follow-up were analyzed. All VFs (static automated perimetry, central 24-2 threshold test) performed were reviewed and reliable VFs (fixation losses <20%, false positives and false negatives <33%) were scored using the Advanced Glaucoma Intervention Study (AGIS) system. Progression of a VF defect was defined as a change of ≥4 from baseline on 2 consecutive VF tests. RESULTS From the 137 eyes of 87 patients with PACG with ≥10 years of follow-up identified, 6% and 30.1% were blind based on initial visual acuity (VA) and VF criteria respectively and 12.0% had an initial AGIS score of 20; these were excluded. Eighty-three eyes from 57 patients (all Chinese, mean age 59.9 ± 8.2 years, 67.5% female) were analyzed. The mean AGIS score was 5.14 ± 4.37 at baseline. VF deterioration was detected in 27 eyes (32.5%) of 21 patients, with 4.8% and 7.2% of eyes progressing to blindness based on VA and VF criteria respectively. On Cox regression, eyes with VF progression had higher mean overall IOP (P < .001), and higher prevalence of previous acute angle closure (AAC, P = .008). CONCLUSIONS Over 10 years, a third of PACG patients were found to have VF progression, with 7% progressing to blindness while on treatment. Eyes with higher mean overall IOP and a history of previous AAC were more likely to have VF progression.

Comparison of two spectral domain optical coherence tomography devices for angle-closure assessment.

PURPOSE To compare two spectral domain optical coherence tomography (SD-OCT) devices for the identification of angle structures and the presence of angle closure. METHODS This was a prospective comparative study. Consecutive patients underwent gonioscopy and anterior segment imaging using two SD-OCT devices (iVue and Cirrus). Images were evaluated for the ability to detect angle structures such as Schwalbes line (SL), trabecular meshwork (TM), Schlemms canal (SC), and scleral spur (SS), and the presence of angle closure. Angle closure was defined as iris contact with the angle wall anterior to the SS on SD-OCT, and nonvisibility of the posterior TM on gonioscopy. Angle closure in an eye was defined as ≥two quadrants of closed angles. AC1 statistic was used to assess the agreement between devices. RESULTS Of the 69 subjects studied (46.4% male, 84.1% Chinese, mean age 64.0 ± 10.5 years), 40 subjects (40 eyes, 58.0%) had angle closure on gonioscopy. The most identifiable structure on Cirrus SD-OCT was the SS (82.2%) and SL on iVue SD-OCT (74.5%). Angle closure was indeterminable in 14.5% and 50.7% of Cirrus and iVue scans (P < 0.001), respectively. Interdevice agreement for angle closure was moderately strong (AC1 = 0.67), but agreement with gonioscopy was only fair (AC1 = 0.35 and 0.50 for Cirrus and iVue, respectively). CONCLUSIONS It was more difficult to determine angle closure status with iVue compared with Cirrus SD-OCT. There was fair agreement between both devices with gonioscopy for identifying angle closure.

Persistence of Patients Receiving Topical Glaucoma Monotherapy in an Asian Population

OBJECTIVE To determine the persistence rates of patients who started taking topical intraocular pressure (IOP)-lowering monotherapy in a Singapore eye hospital. METHODS This was a retrospective review of patients who started taking a single IOP-lowering medication between October 1, 2005, and September 30, 2006. Pharmacy dispensing records were traced for 3 years from the date of first prescription. A patient was defined as persistent if he or she was prescribed the same medication before or within 90 days after the previous prescription had lapsed during this period. Persistence was assessed after 1 and 3 years. RESULTS A total of 2781 patients started taking topical IOP-lowering monotherapy during the 1-year study period. The mean (SD) age was 61.1 (15.7) years; 50.2% were male, and most were Chinese (81.1%) or Singaporean residents (85.4%). After 1 year, only 22.5% of patients (626 of 2781) persistently received the same therapy, which decreased to 11.5% (320 of 2781) after 3 years. Prostaglandin analogues had better persistence rates at 1 year compared with timolol maleate (29.6% vs 23.7%; P = .004) and all other medications combined (29.6% vs 20.6%; P < .001). Those who were not persistent at year 1 were younger (P < .001) and more likely to not be Singaporean (P = .008), not receiving government subsidies (P < .001), and receiving unilateral therapy (P < .001). CONCLUSIONS In this hospital-based study, the persistence rate of patients who started taking topical IOP-lowering monotherapy was low after 1 (22.5%) and 3 years (11.5%). These rates are lower than in previous studies in Western countries and may have implications for glaucoma care in Singapore and other parts of Asia.

Corneal Graft Survival and Intraocular Pressure Control after Descemet Stripping Automated Endothelial Keratoplasty in Eyes with Pre-existing Glaucoma

PURPOSE To describe the effect of Descemet stripping automated endothelial keratoplasty (DSAEK) on intraocular pressure (IOP) and corneal graft survival in eyes with pre-existing glaucoma or ocular hypertension. DESIGN Retrospective, observational case series. METHODS We performed a retrospective review of 184 eyes that underwent DSAEK from January 2007 through May 2009 at the Singapore National Eye Centre. Eyes with pre-existing glaucoma or ocular hypertension that underwent DSAEK were included, whereas those with a follow-up period of less than 12 months were excluded. Main outcome measures were graft failure and need for additional IOP-lowering treatment after DSAEK. RESULTS Forty-seven eyes (51% male; mean age, 66.6 years) with glaucoma underwent DSAEK and were followed-up for a mean of 27.3 ± 8.5 months. Before DSAEK, 60% were taking at least 1 topical IOP-lowering medication, whereas 14 eyes (30%) previously had undergone glaucoma filtration surgery. After DSAEK, visual acuity improved by a mean of 5.4 ± 3.7 Snellen lines. Seventeen percent of grafts failed at a mean of 12.8 ± 7.0 months. The mean IOP increased by 2.1 mm Hg to 16.0 ± 2.5 mm Hg, with 62% requiring additional IOP-lowering treatment and 28% needing filtration surgery at a mean of 9.3 months after DSAEK. Eyes without prior filtration surgery and eyes that underwent additional intraoperative procedures during DSAEK were 10 and 18 times more likely to require IOP-lowering treatment after DSAEK (P = .002 and P = .008), respectively. CONCLUSIONS With prompt and appropriate intervention, IOP in glaucomatous eyes undergoing DSAEK can be controlled with minimal increase after DSAEK. Eyes with previous filtration surgery require fewer medications to control elevated IOP than eyes that have not had previous surgery.

Angle imaging: advances and challenges.

Primary angle closure glaucoma (PACG) is a major form of glaucoma in large populous countries in East and South Asia. The high visual morbidity from PACG is related to the destructive nature of the asymptomatic form of the disease. Early detection of anatomically narrow angles is important and the subsequent prevention of visual loss from PACG depends on an accurate assessment of the anterior chamber angle (ACA). This review paper discusses the advantages and limitations of newer ACA imaging technologies, namely ultrasound biomicroscopy, Scheimpflug photography, anterior segment optical coherence tomography and EyeCam, highlighting the current clinical evidence comparing these devices with each other and with clinical dynamic indentation gonioscopy, the current reference standard.

Demonstration of angle widening using EyeCam after laser peripheral iridotomy in eyes with angle closure.

PURPOSE To evaluate EyeCam in detecting changes in angle configuration after laser peripheral iridotomy (LPI) in comparison to gonioscopy, the reference standard. DESIGN Prospective comparative study. METHODS Twenty-four subjects (24 eyes) with primary angle-closure glaucoma (PACG) were recruited. Gonioscopy and EyeCam (Clarity Medical Systems) imaging of all 4 angle quadrants were performed, before and 2 weeks after LPI. Images were graded according to angle structures visible by an observer masked to clinical data or the status of LPI, and were performed in a random order. Angle closure in a quadrant was defined as the inability to visualize the posterior trabecular meshwork. We determined the number of quadrants with closed angles and the mean number of clock hours of angle closure before and after LPI in comparison to gonioscopy. RESULTS Using EyeCam, all 24 eyes showed at least 1 quadrant of angle widening after LPI. The mean number of clock hours of angle closure decreased significantly, from 8.15 +/- 3.47 clock hours before LPI to 1.75 +/- 2.27 clock hours after LPI (P < .0001, Wilcoxon signed rank test). Overall, gonioscopy showed 1.0 +/- 1.41 (95% CI, 0.43-1.57) quadrants opening from closed to open after LPI compared to 2.0 +/- 1.28 (95% CI, 1.49-2.51, P = .009) quadrants with EyeCam. Intra-observer reproducibility of grading the extent of angle closure in clock hours in EyeCam images was moderate to good (intraclass correlation coefficient 0.831). CONCLUSIONS EyeCam may be used to document changes in angle configuration after LPI in eyes with PACG.

Pseudophakic rhegmatogenous retinal detachment in a large Asian tertiary eye centre: a cohort study.

Background:  To determine the incidence and identify risk factors for the development of rhegmatogenous retinal detachment in patients who had cataract surgery at the Singapore National Eye Centre between 2001 and 2003.

Future requirements for and supply of ophthalmologists for an aging population in Singapore

BackgroundSingapore’s population, as that of many other countries, is aging; this is likely to lead to an increase in eye diseases and the demand for eye care. Since ophthalmologist training is long and expensive, early planning is essential. This paper forecasts workforce and training requirements for Singapore up to the year 2040 under several plausible future scenarios.MethodsThe Singapore Eye Care Workforce Model was created as a continuous time compartment model with explicit workforce stocks using system dynamics. The model has three modules: prevalence of eye disease, demand, and workforce requirements. The model is used to simulate the prevalence of eye diseases, patient visits, and workforce requirements for the public sector under different scenarios in order to determine training requirements.ResultsFour scenarios were constructed. Under the baseline business-as-usual scenario, the required number of ophthalmologists is projected to increase by 117% from 2015 to 2040.Under the current policy scenario (assuming an increase of service uptake due to increased awareness, availability, and accessibility of eye care services), the increase will be 175%, while under the new model of care scenario (considering the additional effect of providing some services by non-ophthalmologists) the increase will only be 150%. The moderated workload scenario (assuming in addition a reduction of the clinical workload) projects an increase in the required number of ophthalmologists of 192% by 2040.Considering the uncertainties in the projected demand for eye care services, under the business-as-usual scenario, a residency intake of 8–22 residents per year is required, 17–21 under the current policy scenario, 14–18 under the new model of care scenario, and, under the moderated workload scenario, an intake of 18–23 residents per year is required.ConclusionsThe results show that under all scenarios considered, Singapore’s aging and growing population will result in an almost doubling of the number of Singaporeans with eye conditions, a significant increase in public sector eye care demand and, consequently, a greater requirement for ophthalmologists.