The Peterborough scheme for community specialist optometrists in glaucoma: a feasibility study.

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.

Hydroview lens implant calcification: 186 exchanges at a district general hospital.

AIM: This paper describes the experience at a district general hospital of coping with an abrupt onset of calcification of Hydroview intraocular lens (IOL) implants requiring exchange surgery mostly for symptoms of glare, even though the visual acuities were relatively good. METHODS: In this retrospective study, the operative details of 174 consecutive lens exchanges by one surgeon were retrieved from the surgeon's notes. Of these, pre and post-operative details of 106 consecutive patients were obtained from the hospital notes. RESULTS: Of the 174 lens exchanges, all were sutureless except one and 31 eyes (18%) had had previous capsulotomies. Of 143 eyes with intact posterior capsules, eight (5.6%) needed anterior vitrectomy. Lens replacements were in the bag in 136 (95%), in the sulcus in five (3.5%), and in the anterior chamber in two (1.5%). Of the 31 eyes with previous capsulotomies, 10 (32%) needed anterior vitrectomy. Lens replacements were in the bag in 22 (71%) and in the sulcus in the remaining nine cases (29%). Postoperatively the best-corrected visual acuity was improved in 53%, remained the same in 35%, and deteriorated in 12%. CONCLUSION: The lens exchange procedure was mostly predictable with satisfactory visual results allowing preoperative counselling of risks to be similar to that for cataract surgery. The onset and resolution of the period of implantation of lenses requiring exchange has not been explained.

Prevalence of primary open angle glaucoma in general ophthalmic practice in the United Kingdom.

AIM: To estimate the predicted prevalence of primary open angle glaucoma (POAG) from the activity of a local ophthalmology department. METHOD: Using clinic audit data, the local incidence and prevalence of POAG in the registered population of two primary care trusts were calculated. RESULTS: The local derived prevalence estimate for POAG was 978 per 100 000 people aged 40-89 years (95% CI 753 to 1272) compared with the expected prevalence from a published model of 1230 people per 100 000 people aged 40-89 years. CONCLUSION: The derived prevalence was not statistically significantly different from that predicted. Based on the published evidence that about half of the POAG cases are undetected, it would have been expected that local audit figures would have yielded figures about 50% lower than the epidemiological model. The main reason for this higher prevalence is thought to be differences in the diagnostic criteria used. This lack of consensus on the case definition for POAG is a deficit, which will hamper future needs assessment.

Cataract surgery and the optometrist.

PURPOSE: To determine the outcome of discharge on the first day following cataract surgery and the feedback from patients' optometrists. METHODS: Casenotes of patients who had cataract surgery between 1 April 1997 and 30 June 1998 were analysed. Patients without complications were discharged on day 1 and advised to see their optometrist at 1 month. Patients were given a form for refraction with a pre-paid envelope for their optometrist. Completed letters from the optometrists were returned to the hospital to be analysed by the principal surgeon and acted on appropriately. A questionnaire was sent out to patients whose notes did not contain any information after the first post-operative examination. RESULTS: A total of 318 eyes from 288 patients underwent cataract surgery. Completed forms from the optometrist were received in 245 (77%) cases; no optometrist's letter was found in the remaining 73 cases (23%). Of these 73 patients, 50 (68%) had other ocular pathology requiring hospital follow-up and 9 had died. There were only 6 patients about whom post-operative information could not be obtained. There were no significant differences regarding the age and sex of those who did or did not attend the optometrist. CONCLUSION: Patients without complications can be discharged to the care of their optometrist on the first day following cataract surgery. With good communication between hospital and the optometrist, better use can be made of available resources.

The effect of perioperative embolisation on visual function in patients undergoing carotid endarterectomy.

OBJECTIVES: To investigate the effect of carotid artery embolisation detected by transcranial Doppler (TCD) monitoring during carotid endarterectomy (CEA) on visual function. DESIGN: A prospective study. Visual function was assessed by an independent ophthalmalogist. MATERIALS: One hundred consecutive patients undergoing carotid endarterectomy. METHODS: All patients underwent pre- and postoperative retinal fundoscopy and automated visual field analysis. Intraoperative emboli were detected by continuous TCD monitoring of the middle cerebral artery. RESULTS: Preoperatively, six patients had fundoscopic evidence of silent retinal embolisation, five patients had visible emboli associated with amaurosis fugax. Visual field analysis found no significant difference between ipsi- and contralateral eye scores. Only patients with occlusions of major retinal vessels had clinically reduced visual function. Intraoperatively TCD identified embolisation in 83/91 of monitored operations. Postoperatively, ipsilateral visual field scores deteriorated while contralateral eye scores remained unchanged, however only one new retinal embolus was detected. The incidence of TCD detected embolisation was not associated with a corresponding deterioration in postoperative visual function. CONCLUSIONS: (1) A group of patients can be identified who experience "silent" retinal embolisation prior to CEA. (2) Clinically significant retinal embolisation resulting from CEA is uncommon. (3) CEA is associated with a deterioration in the visual field scores for the ipsilateral eye compared with the contralateral eye but the mechanism for this small but significant deterioration remains unclear.

Causes of uveitis in the general practice of ophthalmology. UCLA Community-Based Uveitis Study Group.

PURPOSE: Most uveitis case series have come from tertiary care centers, and the relative frequencies of disorders they report may reflect referral bias. We sought information about the types of uveitis encountered in the general practice of ophthalmology. METHODS: We prospectively examined 213 consecutive cases of general uveitis, defined as intraocular inflammation other than cytomegalovirus retinopathy, seen by a group of community-based comprehensive ophthalmologists. This group of cases was compared with 213 consecutive cases of general uveitis examined by a uveitis specialist at a university referral center in the same community. All cases were categorized by anatomic site of inflammation and disease course, and, if possible, they were assigned a specific diagnosis. Cases of cytomegalovirus retinopathy and masquerade syndrome seen during the same intervals were recorded separately. RESULTS: The distribution of general uveitis cases by anatomic site of disease was significantly different between the community-based practices (anterior, 90.6%; intermediate, 1.4%; posterior 4.7%; panuveitis, 1.4%) and the university referral practice (anterior, 60.6%; intermediate, 12.2%; posterior, 14.6%; panuveitis, 9.4%; P < .00005). A cause or clinical syndrome could be assigned to 47.4% of cases in the community-based practices, and to 57.8% of cases in the university referral practice (P = .03). HLA-B27-associated anterior uveitis, cytomegalovirus retinopathy, and toxoplasmic retinochoroiditis were among the five most common forms of uveitis in both practice settings. CONCLUSION: The relative frequencies with which various forms of uveitis are seen in a tertiary referral center do not necessarily reflect the experience of ophthalmologists from the community in which the center is located. Anterior uveitis and disorders of sudden onset constitute a greater proportion of cases seen by community-based comprehensive ophthalmologists.

Effects of hypoxemia on the electroretinogram in diabetics.

PURPOSE: To identify any relationship between retinal dependence on oxygen and the presence or absence of retinopathy in a group of patients with the same duration of diabetes, based on the proposal that diabetic retinopathy results from long-term adaptation to the Crabtree effect, i.e., reduction of oxidative phosphorylation caused by increased intracellular glucose concentrations. METHODS: Electroretinograms were recorded on 17 patients with insulin-dependent diabetes (of 15 to 17 years duration) and 10 healthy controls. Recordings were made under normal conditions and then after 4 min of hypoxemia (oxygen saturation, 80%). Retinopathy status was assessed from fundus photographs. RESULTS: Electroretinogram b-wave amplitudes of seven patients without retinopathy were reduced to 69% by the hypoxemia compared to a reduction to 88% for 10 patients with retinopathy (p = 0.039). CONCLUSIONS: The relative sensitivity to hypoxemia of patients without retinopathy suggests greater dependence on oxidative phosphorylation than in patients with retinopathy. The results appear to be consistent with the Crabtree effect hypothesis. Downregulation of tissue oxygen consumption by the Crabtree effect would lead to a reduction of retinal blood flow by autoregulation and to a reduced concentration of adenosine triphosphate in the retina.

Clinical relevance of intraoperative embolization detected by transcranial Doppler ultrasonography during carotid endarterectomy: a prospective study of 100 patients.

A study was performed to investigate the clinical significance of microembolization detected by transcranial Doppler ultrasonography (TCD) by determining the quantity and character of emboli and correlating these with neurological and psychometric outcome, fundoscopy, automated visual field testing and computed tomographic brain scans in 100 consecutive patients undergoing carotid endarterectomy. Embolization was detected in 92 per cent of successfully monitored operations. Most emboli were characteristic of air and not associated with adverse clinical outcome. However, more than ten particulate emboli during initial carotid dissection correlated with a significant deterioration in postoperative cognitive function. A relationship between persistent particulate embolization in the immediate postoperative period, and both incipient carotid artery thrombosis and the development of major neurological deficits was observed. Immediate intervention, based on TCD evidence of embolization, has the potential to avert neurological deficits resulting from particulate embolization.

Impaired contraction and endothelium-dependent relaxation in isolated resistance vessels from patients with insulin-dependent diabetes mellitus.

1. An increase in capillary blood flow and pressure has been implicated in the pathogenesis of diabetic microangiopathy. Abnormal vascular reactivity of the resistance vasculature may play a contributory role by permitting alterations in regional haemodynamics. 2. We have studied the contractile behavior of isolated resistance arteries from normotensive patients with insulin-dependent diabetes mellitus and non-diabetic matched control subjects. Contractile responses to potassium (123 mmol/l), noradrenaline (10(-8) to 3 x 10(-5) mol/l) and angiotensin II (10(-11) to 3 x 10(-8) mol/l) were recorded. Relaxation studies were performed in maximally contracted vessels using acetylcholine (10(-8) to 10(-5) mol/l) and bradykinin (10(-9) to 10(-6) mol/l) (endothelium-dependent) and sodium nitroprusside (10(-9) to 10(-5) mol/l) (endothelium-independent). 3. The maximal contractile responses to potassium (P < 0.05), noradrenaline (P < 0.01) and angiotensin II (P < 0.01) were depressed in diabetic patients. Relaxation to acetylcholine was impaired (P < 0.05), but was normal with bradykinin and sodium nitroprusside. 4. These results suggest that there may be a defect in the endothelial cell acetylcholine receptor excitation-coupling in diabetes mellitus rather than a decreased ability to synthesize and release endothelium-derived relaxing factor. Impaired contraction and endothelium-dependent relaxation of resistance arteries in diabetic patients may contribute to the development of diabetic microangiopathy by causing an increase in tissue blood flow, a rise in capillary pressure and, as a result, an increase in vascular permeability.

Resistance of diabetic rat electroretinogram to hypoxemia.

PURPOSE: To investigate the mechanisms of the known electroretinographic abnormalities of diabetic rats and to explore effects of hypoxemia. METHODS: Subretinal and vitreal microelectrodes were used to isolate the retinal and retinal pigment epithelial components of the electroretinogram. Normoxic and hypoxemic recordings were taken from nine normal and six streptozotocin-diabetic, anesthetized, paralyzed, and ventilated pigmented rats. RESULTS: When inspired O2 was reduced the retinal pigment epithelial c-wave component of most of the normal rats diminished, whereas those of the diabetic rats, though initially smaller, were more resistant to the episode of hypoxemia (P = 0.0061). A similar trend was seen in other components. CONCLUSION: It is proposed that the reduced sensitivity of the diabetic electroretinogram to hypoxemia results from a reduced dependency of the diabetic retina on oxygen. This reduced dependence may follow from a shift in adenosine triphosphate production whereby oxidative phosphorylation is reduced by the high level of retinal intracellular glucose (Crabtree effect). A reduced oxygen demand would cause a transient increase in retinal PO2, leading to a reduction in retinal blood flow. The resulting chronic hypoperfusion of the retinal circulation may deprive the retina of vital, non-energy-related substances.