Adrian Tey

Floppy iris behaviour during cataract surgery: associations and variations

Aim: To assess the association of floppy iris behaviour during cataract surgery with use of α-1-antagonists and diabetes mellitus. Methods: 1842 eyes of 1786 patients undergoing phacohoemulsification surgery were prospectively enrolled. The use of commonly prescribed α-1-antagonists and the presence or absence of diabetes mellitus were noted. The occurrence of any of the features of the intraoperative floppy iris syndrome (IFIS) was noted by surgeons blinded to the patient’s history. Results: 57% of patients receiving tamsulosin showed features of IFIS compared with 1% of the non-tamsulosin group (p<0.001). Of these, more than half the patients manifested the syndrome in an incomplete form. Only 1 of the 51 patients receiving other α-1-antagonists had IFIS. Diabetes was also not associated with IFIS (p = 1). Conclusions: Tamsulosin is significantly associated with floppy iris behaviour during cataract surgery. But not all of these patients will necessarily show all or any features of IFIS. The floppy iris syndrome is likely to represent a continuum of severity. Various undefined factors, diabetes not being one of them, may have a contributory role. Non-selective α-1-antagonists are unlikely to be associated with IFIS.

Imaging and Evaluation of Corneal Vascularization Using Fluorescein and Indocyanine Green Angiography

PURPOSE To evaluate indocyanine green angiography (ICGA) and fluorescein angiography (FA) in imaging and quantifying corneal neovascularization (CNV). METHODS Patients with CNV were studied using a standardized protocol of color digital photography, FA, and ICGA. Images were graded independently by two observers and assessed for quality, phases of fluorescence, and leakage. Areas of CNV and vasculature geometric properties were analyzed and quantified by an automated program. RESULTS Twenty-three patients with good quality images were included. Mean times to appearance of ICG and fluorescein were 17 and 20 seconds (P = 0.10). Best images for analysis were obtained at 64 seconds for ICGA and 47 seconds for FA. CNV not apparent on color or FA, particularly in the presence of scarring, was well delineated by ICGA. Leakage of ICGA did not occur. Fluorescein leakage from apical CNV images occurred significantly earlier (32 seconds) in patients with CNV of <6-month duration than those of >1-year (50 seconds) duration (P = 0.04). Mean area of CNV and vessel diameter were similar with ICGA (8.79 mm(2), 0.058 mm) or FA (7.74 mm(2), 0.054 mm) but significantly larger than on color (1.94 mm(2), 0.026 mm) images (P < 0.01). Vessel tortuosity was similar on ICGA (1.16), FA (1.17), and color (1.15) (P = 0.27). CONCLUSIONS Combined use of FA and ICGA are valuable tools with which to assess CNV and provide better vessel delineation than can be obtained with only color images. Parameters used to assess CNV, such as leakage, area, diameter, and tortuosity, may be useful measures for evaluating treatment. Videography is useful for detecting early leakage.

Quantifying changes in corneal neovascularization using fluorescein and indocyanine green angiography

PURPOSE To quantify changes in corneal neovascularization in patients with active keratitis after treatment using color imaging, fluorescein angiography (FA), and indocyanine green angiography (ICGA). DESIGN Prospective, interventional case series. METHODS Twelve consecutive patients were studied. A comparison of corneal neovascularization parameters was undertaken before and after resolution of the keratitis. A slit-lamp digital camera acquired images of the neovascularization using color imaging, FA, and ICGA. The best-quality images were selected using a grading system, and the neovascular regions of interest were analyzed using automated in-house software. The parameters of analysis were vessel area, diameter, tortuosity, and FA dye leakage. RESULTS There was a significant reduction in the area of neovascularization after treatment on color imaging (0.78 mm(2); P < .05), FA (2.33 mm(2); P < .01), and ICGA (2.07 mm(2); P < .01). There was also a significant reduction in mean vessel diameter across the region of interest for each patient, more marked on FA (42.74 to 32.52 μm; P < .01) and ICGA (44.77 to 33.29 μm; P < .01) than on color imaging (29.10 to 25.17 μm; P < .01). A significant change in vessel tortuosity was not observed. There was a significant increase in FA dye leakage time (12.41 seconds; P < .05) after treatment. CONCLUSIONS We demonstrate application of an objective method for analyzing changes in corneal neovascularization. The excellent vessel delineation with ICGA even in the presence of stromal scars makes it an ideal agent for measurement of vessel parameters. FA is useful at detecting vessel leakage, and the time to leakage provides a possible measure of vessel staging.

Influence of graft size on graft survival following Descemet stripping automated endothelial keratoplasty

Purpose To evaluate graft size on outcome following Descemet stripping automated endothelial keratoplasty (DSAEK) Methods Consecutive patients who had undergone a DSAEK for Fuchs endothelial dystrophy (FED) and pseudophakic bullous keratopathy (PBK) with at least 1 year of follow-up. Patients were divided into three groups according to the size of the donor trephine: <9, 9 and 9.5 mm. Main outcomes were postoperative best corrected visual acuity (BCVA) and graft failure. Grafts were prepared using an automated microkeratome. For larger grafts (≥9 mm), a manual dissection of the residual peripheral ring of anterior lamella was performed before trephination. Donor age, endothelial cell density (ECD) and postmortem times; recipient details including risk factors, comorbidity, surgical complications and postoperative BCVA and graft survival were analysed. Results Of 174 patients, 131 were included: 84 (64%) with FED and 47 (36%) with PBK. Mean preoperative and postoperative BCVA were 1.01±0.76 and 0.2±0.2 logMAR, respectively, at 12 months with 80.5% achieving 20/40 or better. Postoperative BCVA was significantly associated with ECD (p=0.005), PBK or FED (p=0.004), risk factors (p=0.007) and comorbidity (p=0.016). Eleven patients (8.40%) experienced endothelial graft failure; 17.86% for <9 mm, 7.69% for 9 mm and 3.84% for 9.5 mm trephine sized grafts. Graft failure was significantly associated with ECD (p=0.039) and graft trephine size (p=0.04). Conclusions Larger grafts occupy a smaller chord length in the eye than the trephine size and are expected to provide 10%–20% more endothelial cells. Increased graft size and donor ECD is significantly associated with a reduced graft failure rate.

Marginal corneal vascular arcades.

PURPOSE To determine the metrics of the marginal corneal vascular arcades (MCA). METHODS The MCA and filling pattern was investigated using indocyanine green dye angiography (ICGA) in the fellow eye of patients with treated unilateral keratitis. Images were acquired using a scanning laser ophthalmoscope. Five contiguous squares (100 pixels) were aligned beyond the inner row of vessels extending approximately 700 μm into the limbal region and spanning an arc length of approximately 4 mm of the peripheral cornea. Geometrical properties of the MCA were determined using programs written in a numerical computing environment. RESULTS A total of 17 patients (24-88 years) were included. Filling of the inferior corneal quadrant occurred first, followed by superior, nasal, and temporal quadrants. Mean area of a vascular loop of the MCA was 11.87 × 10⁻³ mm² (SD: 10.44 × 10⁻³ mm²) skewed (2.20) toward smaller sizes. Mean circumference of a vascular loop was 422.5 μm (SD: 218.7 μm) with major and minor axes of 158.9 μm and 90.8 μm. There were five (SD: 1.8) branches per loop with a segment length of 89.5 um (SD 163.8 μm). Vessels were tortuous (mean 0.19, SD: 0.16) with a fractal number of 1.51 (0.12). There were significant differences between subjects in vessel loop area (P = 0.003) and number of branches (P = 0.002). Speed of flow was circumferential along the innermost row and measured at 0.22 mm/s in one subject. CONCLUSIONS The MCA comprise a network of branched interlinked elliptical loops supporting circumferential blood flow in the corneal periphery. There was no definable change in vascular pattern extending into the limbal region.

Pterygium: are we any closer to the cause?

Pterygium is derived from pteron, the Greek word for wing. It is an abnormal wing-like growth that can be found on the neck, at joints and between digits, as well as on the eye (these pterygia are not necessarily related to each other). Man has recognised it as an ocular surface disease for many centuries (it is interestingly almost exclusive to humans). Indeed Egyptian papyri from as far back as 1600–1300 BC show that pterygia were not an infrequent abnormality then. Epidemiological studies now show that its prevalence varies from as low as 0.7% in Denmark (n=810) and 1.1% in non-Aboriginal Australians (n=40 799) to as high as 30.8% in Japan (n=3762) and 33.01% in China (n=4214).1 As ophthalmologists we obviously recognise pterygium as an abnormal triangular non-malignant fibrovascular mass most often on the nasal aspect of the conjunctiva and cornea. This is associated with inflammation and neovascularisation. Moderate disease results in increasing regular and irregular astigmatism and in severe cases there is loss of corneal transparency. The mainstay of conventional definitive treatment is surgical. If the pterygium is either excised alone (bare sclera technique) or if the conjunctival edges are sutured, there is a recurrence rate of 30–70%.2 To reduce recurrence, we have effectively developed certain adjunctive measures including replacing the limbal-conjunctival defect with a conjunctival autograft3 or amniotic membrane4 (less than 10% recurrence). Recent modifications to this include the …

Femtosecond laser‐assisted lamellar keratectomy for corneal opacities due to macular dystrophy: an interventional case report

Superficial corneal opacities can have a significant effect on visual acuity, especially if they are along the visual axis. In these cases, surgical interventions must be considered, such as anterior lamellar keratoplasty and phototherapeutic keratectomy (PTK). These techniques have been associated with irregular resection, keratectasia and astigmatism, which can lead to disabling visual effects. We describe a case in which planned lamellar keratectomy using the femtosecond laser (FSL) deferred more invasive surgery and provided significant visual improvement and aided histological diagnosis in a patient with poor vision secondary to bilateral corneal opacities of unknown aetiology. A 63-year-old man was referred with blurred vision and glare in both eyes. He had a long-standing history of bilateral corneal opacities of unknown aetiology and a history of laryngeal cancer. Best spectacle-corrected visual acuity (BSCVA) was LogMAR 0.78 OD and 0.60 OS. Subjective refraction was +2.25/+9.00 × 143 OD and +0.50/ +6.00 × 160 OS. Slit lamp biomicroscopic examination revealed multiple, bilateral gray-white stromal opacities, principally located in the anterior stroma, throughout the cornea (Fig. 1). The surgical option of an anterior lamellar keratoplasty was offered but was declined, and the patient instead opted for a therapeutic FSL lamellar keratectomy. The right eye was treated first, followed by the left. The preand postoperative keratometric values as measured by corneal topography (Orbscan IIz instrument, Bausch & Lomb, Germany) are shown in Table 1. A free corneal flap of diameter of 9.5 mm and 110 μm in thickness was created for each eye using the FSL (Ziemer FEMTO LDV, Ziemer, Germany) with a bed energy of 900 mW. The excised flap was then sent for histology. There were no perioperative or postoperative complications. Histology of the excised flap of tissue confirmed the diagnosis of macular dystrophy. At 24 months BSCVA was logMAR 0.17 in both eyes. Subjective refraction was +0.50/+4.25 × 123 OD and −1.50/+3.00 × 160 OS. Slit lamp biomicroscopic examination showed residual but much reduced corneal haze, not affecting the visual axis (Fig. 1). The refractive surgical effect showed a change in the refractive error (myopic shift and reduction in astigmatism) of −1.14/−6.23 × 154 OD and −2.00/−3.00 × 160 OS, as shown in Table 1. The goal of treatment of anterior stromal opacities of the cornea is to ablate the opacities in the visual axis and remove the least amount of tissue possible to achieve the optimal visual outcome. Treatment options include anterior lamellar keratectomy using a microkeratome with or without PTK, as well as PTK with or without Mitomycin C, which have been associated with irregular resection,

Evaluation of Corneal Vessels

corneal new vessels can result in significant loss of vision as well as reduce graft survival. Recently, newer treatment modalities have been introduced. however, attempts to meet the challenge of evaluating corneal vessels by quantification are evolving. In vivo evaluations range from computer-aided analysis of colour images to determination of area, diameter and tortuousity of blood vessels on indocyanine green angiography images. attempts at developing a fully automated process of evaluation and quantification are hampered by the anatomical variations of limbus, random nature of blood vessels and multiple levels of involvement of the corneal stroma. currently, semi-automated methods require manually fixing the limbus prior to quantification of vessels. using indocyanine green angiography, the full extent of corneal vessels even in the presence of scarring can be determined. With the evolution of new techniques, it is hoped that a robust corneal vessel quantifying tool will be described in the near future that will aid the effectiveness of treatment strategies.

Cornea and Refractive Atlas of Clinical Wisdom Eds: S. A. Melki and M. A. Fava 2011 272pp., Hardcover ISBN: 978-1-55642-867-8 Slack Inc

The hard-cover book ‘Cornea and Refractive Atlas of Clinical Wisdom’ is edited by SA Melki and MA Fava, was first published in March 2011 by Slack Inc. The book assembles the collective wisdom and knowledge of a number of experienced surgeons who are experts in their chosen field. The book has 249 pages divided into seven sections and 32 chapters. These sections consist of ‘Imaging and Diagnostics’, ‘Ocular Surface Disorders’, ‘Infectious Diseases’, ‘Inflammatory Diseases’, ‘Neoplasia and Epithelial Downgrowth’, ‘Dystrophies and Degenerations’, and finally ‘Refractive Surgery’. Within each section, each chapter begins with a detailed description of the condition from diagnosis to symptoms to complications and to eventual treatment methods. One particular feature, which is of interest and without a doubt helpful, is the ‘In My Experience’ section where individual authors share their personal experience and diagnostic pearls on their particular subject. On certain subjects, it is interesting to find that much of their anecdotal experiences have been well-founded over the years compared to the type of information that is awaited from a large clinical trial. Other good features of the book include emphasis on the provision of practical tips, with less dependence on theoretical aspects of particular diseases. The authors are all experts and well-published in the areas each has covered within the book. Overall, this book is well-structured and easy to digest. The accompanying illustrations are of good standard, as expected in an ‘atlas’. The editors have done well in gathering all the authors to share their experience collected over years of clinical practice. This book will be extremely useful for trainees, general ophthalmologists and even experienced corneal and refractive surgeons as a textbook or quick reference guide for practical tips on management.

Methodological issues in corneal collagen crosslinking in post-LASIK keratectasia

Iatrogenic keratectasia is becoming an increasingly recognised complication of laser in situ keratomileusis (LASIK).1 Prior to the paper by Salgado et al ,2 two case reports have been described in the literature using corneal collagen crosslinking (CXL) with riboflavin and ultraviolet A as a treatment option in these patients.3 4 Salgado et al describe a study examining the use of CXL in post-LASIK keratectasia. They included 22 eyes from 15 patients, observing stability of visual acuity (VA) and corneal topography at 12 months. They conclude that CXL may be of …