Acute Chemical Eye Injury and Limbal Stem Cell Deficiency-A Prospective Study in the United Kingdom.

PURPOSE: To analyze the incidence, nature, outcomes, and complications of acute chemical eye injuries, including the incidence of limbal stem cell deficiency (LSCD) and to compare the 2 main classifications for ocular chemical injuries: Roper-Hall (RH) and Dua. METHODS: This is a prospective, consecutive, interventional single-center study between April and October 2009 of all new patients with acute chemical eye injury presenting to the Royal Victoria Infirmary eye emergency department (EED). RESULTS: Of 11,683 patients who attended the EED, 98 patients (110 eyes) presented with acute chemical eye injury (60% male). This represents an estimated annual incidence of 5.6 new cases per 100,000 population. Mean age was 36.5 years (1-78; SD 17.1 years), including 7 children (age <10 years). Fifty-one patients (52%) had work-related injuries. The most common chemical agent was alkali (78%). All 4 RH grade IV cases were unilateral, assault with ammonia, and required early amniotic membrane transplantation as per the protocol, but despite full treatment, they developed total LSCD in the affected eye. CONCLUSIONS: Acute chemical eye injuries are rare. Male patients in the working age group are more prone to work-related chemical injuries, whereas young children tend to have domestic injuries. Grade I, II, and III RH and Dua chemical injuries had a very good prognosis with topical treatment only, whereas RH grade IV (Dua grade IV-VI), mainly assaults with ammonia, progressed to total/severe LSCD despite appropriate management including early amniotic membrane transplantation. The Dua classification includes conjunctival involvement, having a greater value in predicting the final clinical outcome when grading chemical eye injuries.

Progressive idiopathic unilateral corneal endothelial failure of unknown aetiology in phakic eyes.

AIM: To describe a cohort of patients with irreversible unilateral bullous keratopathy (BK) of undetermined aetiology. METHOD: Retrospective, single-centre case series in a tertiary corneal referral centre. RESULTS: Eleven consecutive patients (nine females; mean age 71.7 years) presented from 1999 to 2009 with acute onset unilateral visual loss. At presentation, the best-corrected visual acuity of the affected eyes was 6/9 or worse with mean central corneal thickness (CCT) of 684 (SD 66) µm. Specular microscopy was not possible in the affected eyes. There was no other ocular pathology in the affected eye. The fellow eye remained normal throughout the study (mean endothelial cell density (ECD) of 1980 (SD 736) cells/mm2 and CCT of 536 (SD 34) µm). Topical steroid, antiviral treatments (both topical and systemic) or a combination of both did not yield any improvement. After a mean follow-up of 82.2 months, eight eyes had penetrating keratoplasty (PK). One required two regrafts. Histology showed typical BK features, with endothelial cell (EC) loss and thickened Descemet's membrane (DM). Transmission electron microscopy revealed DM abnormalities in a non-consistent pattern, featuring variable collagen deposition posterior to the non-banded zone. The ECs were degenerated, reduced or absent. Neither viruses nor pseudoexfoliation material was identified. CONCLUSION: While medical treatment is not beneficial, PK appears to offer good results. Non-guttate Fuchs' corneal endothelial dystrophy merits consideration but it would be unusual to see an exclusively unilateral presentation. DM thickening is reflective of a chronic EC loss but the cause of this loss remains elusive.

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.

Pupillary anomaly masquerading as a glaucomatous visual field defect: a case report.

BACKGROUND: Patients are often referred to ophthalmologists with focal visual field defects on routine testing, possibly related to a potential diagnosis of glaucoma. However, examination of the individual patient's ocular characteristics as well as facial characteristics may often reveal a cause of the visual field defect. CASE PRESENTATION: We describe a patient who was found to have a superior visual field defect on routine testing by the optician. Repeat perimetry with pharmacological dilatation of the pupil revealed that the cause of the field defect was related to an eccentric inferiorly displaced pupil, secondary to trauma some years previously. DISCUSSION: Individual patient characteristics, including both ocular, as well as facial, need to be considered, when interpreting any visual field defect.

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.

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.

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.

Redesign and modernisation of an NHS cataract service (Fife 1997-2004): multifaceted approach.

PROBLEM: A Scottish national health service ophthalmic facility was unable to cope with increasing demand for cataract surgery. DESIGN: Multifaceted approach to redesign hospital space to accommodate a cataract unit; to invest in cataract nursing staff to allow more operations under local anaesthesia and as day cases; and to enhance input by general practitioners and optometrists to streamline and reduce false positive cataract referrals. A prospective audit for productivity was undertaken in 2004 (two years after the redesign) and compared against the national cataract surgery audit data for Fife from 1997. SETTING: District general hospital serving a population of 400,000 in south east Scotland. KEY MEASURES FOR IMPROVEMENT: Increasing throughput of cataract surgery while assessing quality of care provided against predefined evidence and Royal College of Ophthalmologists' guidelines, and evaluating training standards for ophthalmic surgical trainees against higher surgical training requirements. STRATEGIES FOR CHANGE: Cataract services were redesigned to increase throughput and to reduce waiting times while preserving the quality of patient care. A secondary end point was to maintain surgical case load mix thus allowing trainees to continue to fulfil the number of operations required to acquire higher surgical training standards. EFFECTS OF CHANGE: In the same three month period 237 cataract operations were carried out in 1997 and 374 in 2004, representing an increase of productivity by 60%. The waiting time for surgery decreased from more than one year to three months. The redesign resulted in almost complete preoperative and postoperative assessment by nursing staff, thus freeing medical time and allowing for more operations. Optometrists' referrals with reports increased significantly (P<0.0001). The number of operations carried out as day cases under local anaesthesia increased, with fewer intraoperative complications and postoperative visits (P<0.0001). The number of operations carried out by trainees more than doubled, from 43 to 100 cases, thus improving training opportunities. LESSONS LEARNT: Modest capital investment in rebuilding space and in staff for cataract services can improve the quality and volume of cataract surgery. Enhancing existing NHS services provides for future need while maintaining training standards, thus potentially obviating the need for independent treatment centres. This model could be used throughout the United Kingdom.