Treatment of aberrant facial nerve regeneration with botulinum toxin A.

PURPOSE: To assess the effect and efficacy of botulinum toxin type A (BTX-A) at reducing and maintaining eyelid synkinesia in aberrant facial nerve regeneration, while concurrently observing for the presence of side effects to differing treatment doses. METHODS: A prospective interventional study of five patients with eyelid synkinesia resulting from aberrant regeneration of the facial nerve. Patients were treated with injections of either 120, 80 or 40 units of BTX-A (Dysport) into the orbicularis oculi. Objective and subjective reduction in synkinesia, maintenance of response and presence of side effects were recorded. RESULTS: All five patients had improvement of the synkinesia with BTX-A treatment. Lower doses were found to be as effective as higher doses. Mean duration of abolished synkinesia was three months. Two patients developed a ptosis which resolved spontaneously. None of the patients treated with the lowest dose of 40 units developed a ptosis. CONCLUSION: Low-dose BTX-A has a lower incidence of ptosis and is effective in the treatment of aberrant facial nerve regeneration.

Clinical and ultrastructural findings in mare's tail lines of the corneal epithelium.

AIMS: Mare's tail lines are uncommon, grey, parallel, tapering epithelial lines, which may give rise to discomfort or to visual symptoms. The authors report the clinical and ultrastructural findings in two patients METHODS: Therapeutic debridement was performed in two patients suffering from mare's tail disorder. The loosely attached epithelium was removed and fixed in glutaraldehyde containing cuprolinic blue and processed in a standard fashion for electron microscopy. RESULTS: Ultrastructural studies showed an avascular, collagenous pannus extending under the whole of the excised epithelium in each case and separated from it by a thickened basal lamina like zone. The basal laminar material extended into the epithelium in folds, in keeping with the clinical features. Interesting ultrastructural features included: (1) a lack of hemidesmosomes in relation to the basal laminar material; (2) trapping of degenerate keratocytes within the invaginating basal laminar folds; (3) an unusual regularity and fine dimensions of the collagen fibrils and proteoglycans making up the subepithelial pannus. The basal laminar material contained proteoglycans and small fibres similar in appearance to long spacing collagen. CONCLUSIONS: Mare's tail lines are caused by basal laminar material, assumed to be chiefly of epithelial origin, which invaginates the corneal epithelium. The presence of occasional keratocytes within the invaginating folds suggests that there may be a stromal contribution to the disorder. The visibility of mare's tail lines in the focal beam of the slit lamp is likely to be related to the thickness and light scattering properties of the invaginations and of the subepithelial deposits. Tractional forces, imposed by lid action, could explain their horizontal disposition.

Functional aspects of the tear film lipid layer.

The lipid layer is an essential component of the tear film, providing a smooth optical surface for the cornea and retarding evaporation from the eye. The meibomian lipids which compose it are well adapted for this purpose. They form a thin, smooth film whose thickness, and probably composition, influences the rate of evaporation. Their melting range ensures sufficient fluidity for delivery to the tear film from the lid margin reservoirs, while the film itself may exhibit a higher viscosity at the cooler temperature of the ocular surface. The factors governing lipid film formation during the blink are not fully understood, but one view is that the polar lipids, interacting with the aqueous sub-phase of the tear film, spread in advance of the non-polar components, which form the bulk of the film. The meibomian lipids stabilise the tear film by lowering its free energy; they carry water into the film during its formation and interact with lipid-binding proteins in the aqueous phase, such as tear lipocalin. The lipocalins, complexed with other tear components, may also contribute to the high, non-Newtonian viscosity of the tear film and its low surface tension, features which are essential for tear film stability. Formation of the lipid film is a complex process. Lipid is delivered to the tear film in the up-phase of the blink, more from the lower than the upper reservoir. The lipid layer comes to a stop well after completion of the blink and remains relatively immobile until it is compressed in the down-phase of the blink that follows. Then, it either retains its structure in a series of subsequent blinks, or is completely re-constituted after mixing with the reservoir lipids. Delivery of meibomian lipid to the marginal reservoirs is mainly the result of continuous secretion, under neural and hormonal control, supplemented by lid action. The reservoirs provide a hydrophobic barrier to tear overspill and to contamination by skin lipids which might destabilise the tear film. They probably also provide the chief route for meibomian lipid excretion.

Causes and management of Descemet's membrane detachment associated with cataract surgery--not always a benign problem.

INTRODUCTION: Detachments of Descemet's membrane (DM) occur with not uncommon frequency during cataract surgery. The figure for extracapsular cataract extraction (ECCE) is 2.6%, and that for phacoemulsification is 0.5%. Most detachments are small and of little visual consequence. Large detachments are rare but can lead to loss of vision. Early recognition and appropriate management is the key to a favourable outcome. This review provides cataract surgeons with guidelines to the management of this problem. METHODS: A review of reported studies on the subject was made using a MEDLINE search. A summary of the reviewed data is presented. RESULTS: The problem is fairly widespread, given the number of cataract operations done today. The important points with regard to aetiology, classification, recognition and appropriate management are presented in this article. CONCLUSION: DM detachment should not be taken lightly because of the potential for serious visual outcome. It may be avoided in a large majority of cases. Appropriate and prompt management may prevent the patient from suffering visual loss should it occur.

The epidemiology of ocular trauma in Singapore: perspective from the emergency service of a large tertiary hospital.

PURPOSE: To describe the epidemiology of ocular trauma from the perspective of the emergency service of a large tertiary hospital in Singapore. METHODS: A prospective survey was conducted over a 3 month period (August to October 1997) on all patients seen at the ophthalmic unit at the Singapore General Hospital's emergency service. Data on clinical presentation, type and cause of injury and use of eye protective devices (EPD) were collected via a standardised interview and examination. RESULTS: A total of 870 persons presented with a diagnosis of ocular trauma, out of the 1,631 patients seen during the study period. Compared with non-trauma cases, trauma cases were more likely to be male (odds ratio (OR): 4.2, 95% confidence interval (95% CI): 3.2, 5.4), non-residents (OR: 6.2, 95% CI: 3.7, 10.5), younger than 40 years of age (OR: 3.2, 95% CI: 2.7, 4.1) and less likely to require follow-up or hospital admission (OR: 0.2, 95% CI: 0.2, 0.3). The three most common types of injuries were superficial foreign body (58.2%), corneal abrasion (24.9%) and blunt trauma (12.6%), while open globe injury occurred in only 17 cases (2%). Comparison with a 10% random sample of all cases seen in the previous 9 months (n = 284) revealed no significant time variation in the types of injuries (p = 0.63). Work-related injuries accounted for 590 (71.4%) cases, where grinding, cutting metal and drilling were the specific activities in more than 90% of the cases. In appropriate settings, only 21.7% of patients with work-related injuries used EPD; 43.7% were provided with EPD, but did not use them at the time of injury; and the remaining 34.6% reported that EPD were not provided. CONCLUSIONS: Ocular trauma at the emergency service level in Singapore involved mainly young non-resident men, were work-related and associated with well-defined activities, and were generally minor. The low prevalence of EPD use reinforces the need for a review of the design and implementation of occupational eye safety programmes, especially among non-resident workers.

Subjective visual experience during extracapsular cataract extraction and intraocular lens implantation under retrobulbar anaesthesia.

PURPOSE: To investigate the subjective visual experience of patients during cataract surgery under retrobulbar anaesthesia. METHODS: One hundred cataract patients who underwent routine extracapsular cataract extraction and intraocular lens implantation under retrobulbar anaesthesia were interviewed by the authors on the same day after their operation regarding their visual experience in the operated eye during surgery. RESULTS: Forty-three men and 57 women were included in the study. Their mean age was 68.4 years (range 40-87 years). Their pre-operative best corrected visual acuity ranged from 6/12 to perception of light. Eighty-four eyes had no other ocular pathology apart from cataract. Twenty patients reported no light perception during the surgery. The rest reported that they could see light (80 patients), one or more colours (56 patients), movements (39 patients), flashes (36 patients), instruments (16 patients) and/or the surgeon's fingers or hands (10 patients). The colours seen included red (29 patients), yellow (29 patients), green (12 patients), blue (11 patients) and orange (2 patients). Fifteen patients saw a spectrum of colours similar to that of the rainbow. Forty-four patients reported that the brightness of light changed during the operation. Five patients found their visual experience frightening. There was no correlation between those who found the experience frightening and the sex or age of patient, presence of coexisting ocular pathology, duration of operation, whether the operation was the first or second cataract operation in the patient, or the type of visual sensation experienced. CONCLUSION: Many patients undergoing cataract surgery under retrobulbar anaesthesia experience a variety of visual sensations that may be frightening in a small proportion of cases.

Pseudomyopia in a patient with blocked ventriculo-peritoneal shunt--a case report.

Accommodative spasm usually encompasses a classical triad of pseudomyopia, esodeviation and pupillary constriction. Accommodative spasm is most often psychogenic in nature; however, it may be associated with other organic diseases of which a rare cause is that of intracranial catheter complications. We report a case of dorsal midbrain syndrome with pseudomyopia in a patient with a blocked ventriculo-peritoneal shunt inserted for aqueductal stenosis. Clinical presentation was unusual in this patient as pseudomyopia occurred with exodeviation and without pupillary constriction.