Elisabeth Macdonald

Surveillance of severe chemical corneal injuries in the UK

Aim: To estimate the incidence of severe chemical corneal injuries in the UK and describe presenting clinical features and initial management. Methods: All patients with severe chemical corneal injury in the UK from December 2005 to November 2006 inclusive were prospectively identified using the British Ophthalmological Surveillance Unit. Reporting ophthalmologists provided information regarding presentation and follow-up. Results: Twelve cases were identified, giving a minimum estimated incidence in the UK of severe chemical corneal injury of 0.02 per 100 000. 66.7% of injuries were in males of working age, 50% occurred at work, and alkali was causative in 66.7%. Only one patient was wearing eye protection at the time of injury, 75% received immediate irrigation. Six patients required one or more surgical procedures, most commonly amniotic membrane graft. At 6 months’ follow-up, the best-corrected visual acuity was 6/12 or better in five patients, and worse than 6/60 in two. Conclusion: The incidence of severe chemical corneal injury in the UK is low. The cases that occur can require extended hospital treatment, with substantial ocular morbidity and visual sequelae. Current enforcement of eye protection in the workplace in the UK has probably contributed to a reduced incidence of severe ocular burns.

Presence of free radicals in intracameral agents commonly used during cataract surgery

Background Free radicals are known to cause cellular damage and are present in ophthalmic preparations. Corneal defence mechanisms are bypassed in intra-ocular surgery. We evaluated commonly used intracameral agents to ascertain the presence of free radicals and investigate the possibility of anterior segment and endothelial toxicity. Methods Samples of 19 commonly used intracameral preparations were analysed for total free radical presence on an Instrument Laboratory IL600 using a Randox Kit for Total Antioxidant Status (RANDOX Laboratories Ltd, Crumlin, UK). Results Free radical concentrations for the 19 intracameral agents ranged from 0 to 3.59 mmol/l, with median value of 0.34 mmol/l (mean value 0.933±1.19 mmol/l). Phenylephrine had the highest presence of free radicals, which were considerably higher than those for 0.5% hydrogen peroxide at all tested dilutions. Other notable results included cefuroxime (0.61 mmol/l), 2% undiluted lidocaine (0.34 mmol/l) and bevacizumab (0.59 mmol/l). Conclusion The results indicate that free radicals are present in intracameral surgical agents and some are in the order of 0.5% hydrogen peroxide. The risks of endothelial damage must be considered when using multiple intracameral preparations in complicated cataract surgery. Free radicals in intracameral preparations may be a contributing cause in cases of toxic anterior segment syndrome.

Free radicals and the pH of topical glaucoma medications: a lifetime of ocular chemical injury?

IntroductionPreservatives in ophthalmic preparations are known to cause ocular surface damage. Excipients can also contribute to oxidative stress in the compromised ocular surface. We evaluated commonly used topical glaucoma medications to ascertain pH levels and the intrinsic presence of free radicals.MethodsSamples of 27 topical glaucoma preparations were analysed for total free radical presence using a Randox Kit for total antioxidant status. Analytical grade indicator paper was used to ascertain pH levels.ResultsFree radical concentrations for these 27 glaucoma preparations ranged from 0 to 4.54 mmol/l, with a median value of 0.66 mmol/l (mean value of 0.662 mmol/l, SD 0.839). Levels of pH ranged from 4.0 to 7.4, with a median value of 6.5 (mean 6.252, SD 0.826). There was no evidence of a direct correlation between these two variables (r=0.232, P=0.275).ConclusionThis study is the first to document the range of pH and concentrations of free radicals intrinsically present in commonly used glaucoma medications. Long-term exposure to preservatives, free radicals, and pH levels could all contribute to ocular surface damage. The effect of excipients could be responsible for patient intolerance when changing products in the compromised ocular surface.

Presence of free radicals in commonly used ophthalmic preparations

Free radicals can cause direct cellular damage, a role increasingly defined in cardiovascular disease, but less distinct in ophthalmology. Preservatives in topical medications are known to cause toxicity and cytotoxic damage to the corneal surface.1 We set out to evaluate if free radicals were present in commonly used ophthalmic preparations and if they were present in sufficient qualities to contribute to ocular surface instability. Samples of commonly used ophthalmic preparations were analysed for total free-radical presence by indirect analysis via Total Antioxidant Status (TAS kit, RANDOX Laboratories, Crumlin, UK). They were contrasted with preservative-free Minims preparations. Various solutions including 0.5% hydrogen peroxide were also assessed to provide an appropriate reference result. Fifty-six ophthalmic preparations available in outpatients were sampled, including 18 Minims preparations, seven topical …

Xerophthalmia—a potential epidemic on our doorstep?

PurposeXerophthalmia refers to the ocular manifestations associated with vitamin A deficiency, including xerosis, keratomalacia, nyctalopia and Bitots spot. Hypovitaminosis A is well-recognised in developing countries, but is rare in the developed world. Most cases in the latter relate to fat malabsorption. Conditions in which vitamin A metabolism or storage is deranged (chronic liver disease, including alcoholism) are also aetiologies. We wanted to see whether this was common in our department.MethodsOral vitamin A supplements were given to patients who presented with hypovitaminosis A.ResultsAll patients were found to have hypovitaminosis A on biochemical testing and responded dramatically to oral vitamin A supplementation, resulting in an improved final visual outcome.DiscussionThis series demonstrates that prompt recognition and treatment of xerophthalmia can lead to rapid recovery and avert significant visual morbidity. The prevalence of xerophthalmia is likely to increase in the developed world largely owing to alcoholic liver disease. It is thought by some that we are on the verge of a potential epidemic. We hope that by increasing the profile of this important public health issue, we may be able to influence future prevalence of hypovitaminosis.

Observation of the in vivo movement of host keratocytes into donor tissue following corneal graft; a novel technique

Background/aims The cornea is a highly cellular structure that exists in a dynamic state of cell loss, renewal and replacement. The limbus contains corneal epithelial stem cells. The progenitor or stem cell of the keratocyte remains poorly defined. The authors sought to investigate the in vivo movement of corneal stromal and epithelial cells using a chromosome in situ hybridisation (CISH) technique on human tissue. Methods Four explanted sex-mismatched human corneal buttons were studied using the CISH technique to identify corneal epithelial and keratocyte cells containing the Y chromosome. Keratocyte identity and lack of infiltrating inflammatory cells were confirmed by immunohistochemistry. The sex mismatch of donor (XX) and host (XY) suggested any identified Y chromosomes cells were of host origin having migrated into the donor tissue. Results Host corneal epithelial cells were identified in all four buttons, and corneal stromal keratocytes were present in three of the four specimens in the central corneal area. Conclusion Defining the corneal cell movements and the location of the progenitor or stem cells has important clinical implications. This study has successfully used the CISH technique to demonstrate the in vivo centripetal movement of corneal stromal keratocytes and epithelial cells. The CISH technique may allow further investigation of the corneal stromal dynamics using archival tissue.

A case for single-use disposable corneal forceps: equipment reliability should be the primary concern

Disposable, single-use surgical instruments are increasingly being used to reduce cross-contamination and infection risks.1–3 Despite the hidden financial and environmental disposal costs, this approach avoids the problems associated with instrument damage during reprocessing. Cataract surgery already benefits from such disposable instruments.4 We wish to detail our experience with corneal forceps and graft management to highlight practical issues within the current financial climate. Currently, our instruments are sterilised off-site, with an anticipated 24 h turn around. A snapshot audit of all ophthalmic instruments available in the outpatients revealed numerous problems, including damaged instruments with non-opposing tips, incorrect labelling, instruments unidentifiable without opening of …

Recurrent Fungal Keratitis Following Penetrating Keratoplasty: An Unusual Source of Infection

Report of a Case. A 75-year-old woman visited us in 2007 with left ocular discomfort for 1 month. She had previous bilateral penetrating keratoplasties (for the right eye in 1998 and for the left eye in 2004) for decompensated Fuch’s endothelial dystrophy. She had undergone trabeculectomy with mitomycin C (in 2006) and was using topical dexamethasone sodium phosphate, 0.1%, daily in the left eye. Her medical history included uterine carcinoma, treated Hodgkin lymphoma, pulmonary embolism, emphysema, hypertension, ischemic heart disease, hyperthyroidism, and renal failure. Visual acuity was 6/12 (20/40) OD with clear corneal graft and 6/36 (20/100) OS. Examination of the left eye revealed a deep stromal infiltrate measuring 2 1.3 mm and with hypopyon (Figure, A). Steroid eyedrops were temporarily stopped, and treatment with cefuroxime sodium, 5%, and gentamicin sulfate, 0.3%, was commenced. Anterior chamber tap and corneal biopsy yielded a heavy growth of C parapsilosis. The treatment regimen was changed to intensive topical fluconazole, 0.2%, ofloxacin, and oral voriconazole (400 mg loading followed by 200 mg twice daily). Topical dexamethasone was reintroduced owing to evidence of rejection at day 7 and was gradually tapered as the abscess and graft edema resolved over the following 2 months. Keratitis recurred 2 months after discontinuing antifungal agents (Figure, B). Empirical treatment with fluconazole, 0.2%, and oral itraconazole, 100 mg twice daily, was commenced. Gentamicin, 1.5%, and cefuroxime, 5%, were added, and itraconazole was changed to voriconazole as the keratitis progressed

Unit-dose dispenser tips: a potential source of ocular injury

Recent advances have enhanced our knowledge of the aetiology, diagnosis and treatment of dry eye disease. For many years, the mainstay of treatment has been artificial tears. Those now available offer a great range of treatment options and provide better-quality replacement tears.1 The Dry Eye Workshop Report 2007 highlighted the features of the ideal lubricant as preservative-free and similar to tears in electrolyte composition, pH and osmolarity.2 Artificial lubricants are used in a wide variety of conditions in many patients worldwide, and attempts to provide the ideal product have led to the development of a vast array of options. Perhaps the most critical advance has been the elimination of preservatives, enabling patients to administer lubricants more frequently without the associated preservative toxicity.2 Many non-preserved preparations are now available.2 These are designed for single use, but some patients ignore manufacturers’ advice and use these more …

The increasingly iatrogenic indications for mitomycin C trabeculectomy over 10 years.

OBJECTIVE The success of trabeculectomy can be adversely affected by certain risk factors. In these cases, the outcome can be improved by the intraoperative use of mitomycin C (MMC). We aimed to investigate the impression that this operation was being performed more often in our unit and that the risk factors were changing. DESIGN Retrospective review. PARTICIPANTS The study involved 107 MMC trabeculectomies during the 2 separate study periods. METHODS Operating theatre logbooks were used to identify patients who had undergone MMC trabeculectomy during 2 separate periods of 32 months, 10 years apart. Patient characteristics, the indication for surgery (previously failed trabeculectomy; aphakic/pseudophakic glaucoma; uveitic, developmental, or rubeotic glaucoma; post-vitreoretinal (VR) surgery glaucoma; postkeratoplasty glaucoma; and other), and follow-up data regarding intraocular pressure control were recorded. RESULTS In the later period, 71 MMC trabeculectomies were performed, compared with 36 in the earlier period, a significant rise (p < or = 0.05). The most obvious change in indication was an increase for postkeratoplasty and post-VR surgery glaucoma, which accounted for 77.1% of the additional operations. Intraocular pressure control at 1 year following surgery was good, particularly in the later period, with 88.8% controlled with the addition of topical medication where necessary. Complications in both periods were rare. CONCLUSIONS The frequency of MMC trabeculectomies has doubled over a 10-year period in our unit. Postkeratoplasty and post-VR surgery glaucomas are increasingly contributing to the caseload of complex glaucoma in our hospital. These cases may be managed effectively with MMC trabeculectomy.