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Descemet membrane detachment (DMD) is a rare but potentially serious surgical complication that arises most often during cataract surgery. A recent study (Couch, S. M. & Baratz, K. H. (2009) Cornea, 28, 1160-1163) cited the case of a patient with DMDs in both eyes, noting that though one detachment was surgically repaired, the other spontaneously reattached and needed no further treatment. A fluid mechanical model of buoyancy-driven aqueous humour flow in the anterior chamber around a DMD is developed to explain this phenomenon. The analytical model is based on the lubrication theory limit of the Navier-Stokes equations. The flow is determined for a fixed geometry and the possible motion of the DMD is then analysed. Numerical calculations are also carried out (using COMSOL© Multiphysics) to confirm the lubrication theory results. The analytical and numerical results both show that, under the correct conditions, either spontaneous reattachment or worsening of the tear may occur. We conclude that it is possible that clinical outcomes for DMDs may be controlled by adjusting the temperature difference across the eye and/or the orientation of the patient.

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PURPOSE: This study assessed the role of specialist optometrists who were working in the community and sharing the care for glaucoma patients with, and under close supervision of, a consultant ophthalmologist working in the Hospital Eye Services (HES) to ensure high-quality standards, safety, and care. METHODS: From February 2005 onwards, the majority of all new glaucoma referrals to our eye department were diverted to our specialist optometrists in glaucoma (SOGs) in their own community practices. Selected patients in the HES setting who were already diagnosed with stable glaucoma were also transferred to the SOGs. The completed clinical finding details of the SOGs, including fundus photographs and Humphrey visual field tests, were scrutinised by the project lead. RESULTS: This study included 1184 new patients seen by specialist optometrists between February 2005 and March 2007. A total of 32% of patients were referred on to the hospital, leaving the remaining 68% patients to be seen for at least their next consultation in the community by the SOGs. The following levels of disagreement were observed between SOGs and the project lead: on cup:disc ratio (11%), visual field interpretation (7%), diagnosis (12%), treatment plan (10%), and outcome (follow-up interval and location) (17%). CONCLUSION: This study indicates that there is potential for a significant increase in the role of primary care optometry in glaucoma management. The study also confirms a need for a significant element of supervision and advice from a glaucoma specialist. The important issue of cost effectiveness is yet to be confirmed.

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We consider and compare the various different kinds of flow that may take place in the anterior chamber of a human eye. The physical mechanisms responsible for causing such flows may be classified as follows: (i) buoyancy-driven flow arising from the temperature difference between the anterior surface of the cornea and the iris, (ii) flow generated by the aqueous production of the ciliary body, (iii) flow generated by the interaction between buoyancy and gravity while sleeping while sleeping in a face-up position, (iv) flow generated by phakodenesis (lens tremor), (v) flow generated by Rapid Eye Movement (REM) during sleep. Each flow is studied using a traditional fluid mechanics/asymptotic analysis approach. We also assess the veracity of a hypothesis that was recently advanced [see Maurice, D.M., 1998. The Von Sallman Lecture 1996: An ophthalmological explanation of REM sleep. Exp. Eye. Res. 66, 139-145, for details] to suggest that, contrary to previous opinion, the purpose of REM during sleep is to ensure corneal respiration in the absence of the buoyant mixing that routinely takes place due to (i) above during waking conditions.

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AIM: To establish the likelihood of, and risk factors associated with, progression of 'macula-on' retinal detachment. METHODS: A multi-centre prospective observational study of patients with acute retinal detachment, not involving the fovea, was conducted over a 6-month period. Data collected included duration of symptoms, visual acuity, presence of posterior vitreous detachment, retinal drawings and subretinal fluid (SRF) distance from the fovea at a minimum of two time points. RESULTS: A total of 82 data sets from 15 institutions were analysed. Of 82 cases 11 (13%) demonstrated progression of fluid. Mean progression in those cases which progressed was 2.3 disc diameters (dd) and the average rate of progression was 1.80 dd/day. Binary regression analysis failed to reveal any statistically significant risk factors for progression. Multiple regression analyses were made to identify risk factors. With distance of SRF from fovea at operation as a function, distance of SRF at presentation was the only statistically significant risk factor. In all, 26% of patients underwent surgery out-of-hours. A total of 83% patients achieved a 6-week best-corrected vision of 6/9 or better. CONCLUSION: Most retinal detachments in this study did not progress within the first few days. The distance of SRF from the fovea at presentation was the only statistically significant risk factor for progression to foveal detachment.

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AIM: To identify the relative incidence and profile of adverse drug reaction (ADR) to various topical ocular hypotensives in a hospital setting. METHODS: All the patients presenting in outpatients clinic and accident and emergency with an ADR to topical hypotensive agent from August 2000 to January 2001 were included in the study. Details regarding the type date of commencing the treatment, the date of developing ADR, time to resolution of the ADR were noted. RESULTS: Over the period of 6 months, 66 patients presented with 73 ADRs. Brimonidine was the most frequent offending agent. In total, 23 (34.8%) presented with ADR after being commenced on treatment for more than 12 months. In all, 16 (24%) patients had IOP > 21 on presentation, eight (12%) patients underwent filtration surgery following the development of ADR. CONCLUSION: Adverse drug reaction to ocular hypotensive agents is not uncommon and can have a major impact on glaucoma management. Delayed presentation and association with raised intraocular pressure presentation emphasise the need for effective patient education to encourage prompt reporting of ADR.

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We study the drainage of the precorneal tear film in humans. A fluid dynamic model for the drainage of the aqueous layer is developed that includes the effects of evaporation and gravity. The model may be reduced to a single nonlinear partial differential equation for the thickness of the aqueous layer. The equation is solved numerically and accurate times for film rupture are obtained for physically realistic parameters. The results indicate that although gravity and evaporation are not the most dominant effects in some parts of the film, they can nevertheless materially affect the film drainage process and should therefore be included in models for tear film drainage.

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A simple model is presented to analyse fluid flow in the anterior chamber of a human eye. It is shown that under normal conditions such flow inevitably occurs. The flow, whose reduced Reynolds number is small, is viscosity dominated and is driven by buoyancy effects which are present because of the temperature difference between the front and back of the anterior chamber. In cases of severe eye trauma or as a result of certain diseases and medical conditions, particulate matter may be introduced into the anterior chamber. The motion and distribution of such particles is analysed and it is shown that the model is capable of predicting well-established and observed features that may be present in a traumatized eye such as hyphemas, keratic precipitates, hypopyons and Krukenberg spindles.

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PURPOSE: Rhegmatogenous retinal detachment combined with spontaneous pre-operative choroidal detachment (RDCD) represents a rare but specific entity, which has in the past been associated with a poor prognosis. This study was designed to determine the efficacy of pars plana vitrectomy with silicone oil injection in the management of this very difficult vitreoretinal problem. METHODS: A retrospective analysis was carried out of 13 eyes of 13 consecutive patients who underwent vitrectomy and silicone oil exchange. RESULTS: In a total of 10 eyes (77%) the first procedure produced anatomical success. Two eyes required a further procedure to achieve retinal reattachment, producing a final anatomical success rate of 92%. CONCLUSION: Pars plana vitrectomy with silicone oil exchange is an effective technique for managing RDCD.

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PURPOSE: To assess the effect of pupil dilation on vision and driving ability. METHODS: A series of tests on various parameters of visual function and driving simulator performance were performed on 12 healthy drivers, before and after pupil dilation using guttae tropicamide 1%. A driving simulator (Transport Research Laboratory) was used to measure reaction time (RT), speed maintenance and steering accuracy. Tests of basic visual function included high- and low-contrast visual acuity (HCVA and LCVA), Pelli-Robson contrast threshold (CT) and Goldmann perimetry (FIELDS). Useful Field of View (UFOV--a test of visual attention) was also undertaken. The mean differences in the pre- and post-dilatation measurements were tested for statistical significance at the 95% level using one-tail paired t-tests. RESULTS: Pupillary dilation resulted in a statistically significant deterioration in CT and HCVA only. Five of 12 drivers also exhibited deterioration in LCVA, CT and RT. Little evidence emerged for deterioration in FIELDS and UFOV. Also, 7 of 12 drivers appeared to adjust their driving behaviour by reducing their speed on the driving simulator, leading to improved steering accuracy. CONCLUSIONS: Pupillary dilation may lead to a decrease in vision and daylight driving performance in young people. A larger study, including a broader spectrum of subjects, is warranted before guidelines can be recommended.

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PURPOSE: Approximately 6% of general practitioners have worked in ophthalmology but to our knowledge the relevance of this training has not previously been evaluated. METHODS: We sent an anonymous questionnaire to all doctors who had held general practitioner registrar (vocational training) posts in ophthalmology in the Northern Region during a 5-year period (1989-1994). RESULTS: Twenty-six of 48 (54%) questionnaires were returned. Twenty-five of 26 respondents (96%) thought the training was useful, with 22 (91.7%) continuing to use some ophthalmic practical skills and 17 (65.4%) said they had received adequate and relevant clinical exposure. Twenty-one (87.5%) of those in general practice felt that they were more confident with eye problems than their peers and 12 (50%) said their referral patterns differed. Eleven (46%) had provided advice for colleagues. However, 9 (34.6%) commented on the large service commitment and 5 (19%) felt that supervision had been inadequate. Only 9 (34.6%) had received relevant teaching and 18 (69%) thought more was necessary. CONCLUSION: We conclude that general practitioner registrar posts in ophthalmology are useful and rewarding but that there is scope for improvement.

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Diclofenac is a non-steroidal anti-inflammatory drug available in an ophthalmic preparation. We present a prospective randomised double-masked placebo-controlled trial involving 40 patients that assessed the effectiveness of topical diclofenac in relieving pain from traumatic corneal abrasions. Statistical analysis of visual analogue and categorical pain scores revealed a significant reduction in pain experienced by subjects in the diclofenac group (p < 0.02).

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A case of an epidermoid cyst in the cerebello-pontine angle presenting with facial pain is reported. The tumour was discovered during neurovascular decompression of the fifth nerve. A pre-operative CT scan was normal. The role of neuroradiological investigation in young patients with trigeminal neuralgia is discussed.

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