Blue-Yellow (B-Y) Perimetry Vs White- White (W-W) in detecting glaucomatous changes

Objectives: To determine if the Koniocellular pathway is broken down before the magnocellular pathway in glaucoma. To determine if there is any significant difference in the results for W-W perimetry vs B-Y perimetry of the same patient. The koniocellular pathway is the first to be damaged in glaucoma and the B-Y method of perimetry testing would be more beneficial to the patient where any change in the progression of their glaucoma would be detected earlier. Design and Methodology: The patients of fitting criteria were randomly selected and brought into the UWI clinic for two visual field tests. Both tests required the patient to do the same thing with the only difference being the colour of lights used. The results recorded for each patient were analysed using the software SPSS. Results: The results showed that although the blue- yellow perimetry detected more visual field defects than the white on white, the difference was not statistically significant at the 0.05 level. Conclusion: Even though SPSS analysis indicated that the results obtained were not significant it was inferred that using the alternative Blue Yellow method of perimetry can be helpful in monitoring those patients who are classed as glaucoma suspects to detect earliest glaucomatous changes.

Microvascular endothelial function and regional differences in vasodilation in the human cutaneous microcirculation in primary open angle glaucoma

Objective:Blood flow in the optic nerve head and finger skin are related in subjects with a primary vascular dysregulation (PVD). Since PVD may also occur in glaucoma, the aim of this study was to investigate the responses of the microcirculatory blood flow at the finger and forearm skin to iontophoresis of endothelial-dependent (acetylcholine - ACh) and endothelial-independent (sodium nitroprusside - SNP) vasodilators in primary open angle glaucoma (POAG). Design and Methodology: We studied 22 patients with POAG and 27 control subjects. The vasodilator responses to iontophoresis of ACh and SNP performed at the finger and forearm skin were determined, with skin microcirculatory blood flow being expressed as cutaneous red cell flux (RCF) as measured by Laser Doppler Flowmetry. Results: ACh and SNP induced significant increases in RCF from baseline (p<0.001) at both the finger and forearm skin sites in POAG patients and controls, but there was no difference in vasodilation between the subject groups. Within controls and POAG patients, for both ACh and SNP, the baseline RCF was higher in the finger than in the forearm skin (p<0.05). The vasodilatory response to ACh in the finger was also higher than in the forearm skin (p<0.05) i controls and POAG. The mean vasodilatory response to SNP in the finger was higher than in forearm skin (p<0.05) in controls and POAG. Conclusions: The vasodilatory responses to acetylcholine in POAG suggest normal microvascular endothelial function. The higher baseline RCF and vasodilatory responses in the finger than in forearm skin sites may reflect the difference in vascularity between these sites.

The Moorfields Safer Surgery System: preventing glaucoma blindness in the Caribbean

Introduction: Glaucoma is the leading cause of blindness in the Caribbean, accounting for 28.4% in Barbados and 32% in Trinidad and Tobago (T&T). In T&T, 28% of glaucoma patients miss clinic appointments and 40% are non-compliant with eye drops. There is a role for surgery in preventing glaucoma blindness. However, the complications of mitomycin C trabeculectomy (MMCT) have deterred local ophthalmologists and patients from selecting this option. The Moorfields Safer Surgery System (MSSS) allows simple modification of surgical technique which can be implemented to improve surgical outcomes. Purpose: To demonstrate the safety and efficacy of the MSSS in the Caribbean. Methods: Thirty-three consecutive MMCT procedures were performed by a single surgeon using the MSSS. Patients were of African descent, 16 male and 8 female. Median age was 56 years (range 34-79 years). Mean pre-operative intraocular pressure (IOP) 23.2 mmHg. In 38%, best-corrected visual acuity (BCVA) was ≤3/60 in at least one eye. Results. IOP was ≤21 mmHg in 92.6% of patients at 1 year and in 87.5% at 5 years. Removal of scleral releasable suture(s) was required in 85%, 5-fluorouracil injection(s) in 85% and bleb needling in 36%. The most common complication was early bleb leak (52%). 91% had excellent or satisfactory bleb morphology. No patient developed endophthalmitis. 73% had equal or better BCVA in the operated eye. Conclusion: Glaucoma in the African Caribbean population is an aggressive disease which affects young adults. Late presentation and non-adherence to topical treatment favour surgical intervention. This study provides evidence that knowledge and skills transfer of the MSSS to the Caribbean is possible. Surgical success and complication rates comparable to best published international data can be achieved.

Medical management of Glaucoma in the 21st century [abstract]

Exploration of the past, current and future trends in the management of glaucoma is presented. Lecture will include discussion of beta-blockers, alpha-agonists, prostaglandins and new medications. (AU)

Systemic acidosis associated with diamox [abstract]

Glaucoma is an optic neuropathy defined by the presence of characteristic morphological alterations to the optic nerve head and suggestive visual field abnormalities. The aetiology of primary open angel glaucoma remains elusive but intraocular pressure is presumably the most important risk factor in all forms of glaucoma. In addition, the intraocular pressure remains the only modifiable risk factor, and current glaucoma therapy focusses on addressing the variable. A variety of drugs is available to reduce the intraocular pressure and they work by reducing aqueous production, increasing aqueous overflow or both. Although generally safe, these medications can be associated with local and systemic side effects. Topical beta blockers and systemic carbonic anhydrase inhibitors are notable for their effects on multiple organ systems and their potential for severe toxity. As with most medications, their safe use requires knowledge of the patient's health status, an awareness of specific contraindications to their use, sensitivity to the effects of ageing on drug metabolism, familarity with drugs which may cause adverse interaction and due diligence in the detection of insidious long-term effects. An illustrative case of marked acid-base imbalance associated with carbonic anhydrase inhibitor use is presented. (AU)

All that glitters is not glaucoma

The twentieth century has witnessed great strides in the understanding and management of the major ophthalmic conditions. For example, the surgical treatment of cataract is being honed to perfection with only the goal of accommodative restoration remaining to complement visual clarity. Understanding of the mode of transmission of Chlamydia trachomaitis, plus the new macrolide antimicrobial, azithromycin, which can cure 80 percent of acute trachoma, offers hope in managing this infection. Similarly, the control of the vector Simulium and the microfilariacidal, Ivermectin, promise to eradicate onchocerciasis volvolus. Increasing understanding of the pathogenesis of the microangiopathy of diabetic retinopathy and the recent trials - Diabetic Control and Complication Trial and the European Prospective Study - have paved the way for the control of this condition. However, our understanding and management of chronic open angle glaucoma remains frustratingly elusive. Problems related to the early detection and monitoring progression remain imprecise and sometimes non-specific and misleading. Two cases are presented to illustrate the limitations of the visual field test and underline the fact that it should never be viewed in isolation. Further treatment modalities will dictate more precise objective tests for monitoring optic nerve function, focusing on early diagnosis and small degrees of progression.(AU)

The outcome of Trabeculectomy with Mitomycin C at the Queen Elizabeth Hospital, Barbados

AIM: To evaluate the efficacy of trabeculectomy with mitomycin-c in a predominantly black population. METHOD: The records of 43 eyes with 34 patients (males 15, females 19; age range 22-87 years), who underwent trabeculectomies with mitomycin-c for uncontrolled glaucoma at the Queen Elizabeth Hospital were reviewed. Forty-three eyes (rt eyes 22, Lt eyes 21, unilateral 25, bilateral 9, combined procedure 4) had trabeculectomies. All surgeries were performed by six surgeons between July 1995 and October 1998. The concentration of mitomycin-c varied from 0.2 to 0.5 mg/ml and was applied over 2 to 5 minutes. RESULTS: We evaluated treatment outcome based on the following categories of surgical results for patients with a pre-operative IOP>21mmHg. 1. The operation was considered successful when the IOP was <21mmHg without any anti-glaucoma medications. 2. The operation was a failure when the IOP was raised >21mmHg and required anti-glaucoma medications to control the IOP. The mean preoperative IOP was 26mmHg and the mean postoperative IOP was reduced to 14mmHG. There was failure in 19 eyes where the IOP was raised over >21mmHg and required anti-glaucoma medications or control. Twenty-four eyes were still functional at 18 months with IOPs less than 21mmHg without any anti-glaucoma medications. Visual acuity (VA) in the functional 24 eyes: the VA remained the same in 9 patients and the VA progressively deteriorated in the remaining 15 patients in spite of reduced IOP after mitomycin trabeculectomies. CONCLUSION: The most common cause of failure after trabeculectomy is scarring at the filtration site due to fibrosis or more appropriately normal healing by fibrosis - mitomycin simply delayed the normal healing. Eyes with pseudopakia are at higher risk for failure. Most of the studies in the past were done in the predominantly white population with a short follow-up period. In contrast, all the patients in this study were of African origin and had at least 18 months follow-up, with mean follow-up of 39 months. To our knowledge, this is one of the longest follow-up studies in a predominantly Black population and is the first in the Caribbean. (AU)

The approach of neuroprotection for the new millennium

A review of the mechanism of retinal ganglion cell and optic nerve damage in glaucoma will be discussed as well as autoregulation of blood flow in the optic nerve. Treatment utilizing the approach of neuroprotection and the evolution of calcium channel blocking activity will be shown. (AU)

Evaluating headaches

Headache is a common affliction and one of the most frequent causes of referral to opthmalmologists. Multiple intra- and extra-cranial disturbances may be responsible for severe head pain and the many structures contained within the head make diagnostic confusion common. Ocular causes of head pain include trauma, inflammation, ocular hypertension, painful neuropathies and asthenopic symptoms. Other than trauma, inflammation is the most common cause of orbital pain but ischaemia and painful neuropathies are not uncommon. In addition, disease involving the para-nasal sinuses is often referred to the eye or orbit. Ocular tumours are infrequent causes of head pain and when pain is present it is usually associated with secondary glaucoma or inflammation. Similarly, pain is uncommon in otherwise silent orbital tumours, but lachrymal gland lesions may be painful in the absence of other outward signs of abnormality. When faced with the patient with unexplained head pain, the opthalmologist must first establish if an ocular cause is present. If none is found, a systematic work-up should be initiated and the patient referred to the appropriate specialist. (AU)

Refractive errors in a black adult population: the Barbados Eye Study

PURPOSE: To describe the prevalence of refractive errors in a black adult population. METHODS: The Barbados Eye Study, a population-based study, included 4709 Barbados-born citizens, or 84 percent of a random sample, 40 to 84 years of age. Myopia and Hyperopia were defined as a spherical equivalent <-0.5 diopters and >+0.5 diopters, respectively, based on automated refraction. Analyses included 4036 black participants without history of cataract surgery. Associations with myopia and hyperopia were evaluated in logistic regression analyses. RESULTS: The prevalence of myopia was 21.9 percent and was higher in men (25.0 percent) than in women (19.5 percent). The prevalence of hyperopia was 46.9 percent and was higher in women (51.8 percent) than in men (40.5 percent). The prevalence of myopia decreased from 17 percent in persons 40 to 49 years of age to 11 percent in those 50 to 59 years of age, but increased after 60 years of age. The prevalence of hyperopia increased from 29 percent at 40 to 49 years of age to 65 percent at 50 to 59 years of age, and tended to decline thereafter. A higher prevalence of myopia was positively associated (P < 0.05) with lifetime occupations requiring nearwork, nuclear opacities, posterior subcapsular opacities, glaucoma, and ocular hypertension. Factors associated with hyperopia were the same as for myopia, except for occupation, and in the opposite direction. CONCLUSION: High prevalences of myopia and hyperopia were found in this large black adult population. The prevalence of myopia (hyperopia) increased (decreased) after 60 years of age, which is inconsistent with data from other studies. The high prevalence of age-related cataract, glaucoma, and other eye conditions in the Barbados Eye Study population may contribute to the findings.(AU)

Viscocanalostomy: A glaucoma surgical technique - Videotape presentation

A surgical technique for decreasing intraocular pressure comprising a two-tiered approach to Schlemm's canal and the trabecular meshwork, was done in 660 heavily pigmented eyes in South Africans of colour and followed for ten years. The canal is opened and maintained with the instillation of viscoelastic, and a "clear window" is created over Descemet's membrane to facilitate continuous leakage of aqueous from the anterior chamber. The second tier is excised and the first tier is sutured tightly to the adjacent sclera, taking great care not to cauterise or injure the "collecting channels" on the surface. This technique was done on both primary and secondary glaucomatous eyes and offers excellent results and minimal complications (AU)

Neuroprotection in glaucoma

Neuroprotection has emerged as an important conception the treatment of ocular neurodegenerative diseases, including glaucoma. In order to identify drugs with neuroprotective potential, animal models of retina and optic nerve degeneration have been developed. The optic nerve mechanical injury and pressure induced retinal ischaemia rodent models evaluate activity at the inner retina/optic nerve; and at the outer retina the light induced photoreceptor degeneration rodent model was utilized. Functional and morphometric assessment of the retina was made up to two weeks following the mechanical insults to quantitate secondary neuronal degeneration after injury. This type of neuronal cell death shares some characteristics with chronic neurodegenerative diseases. Brimonidine, an alpha-2 adrenoceptor agonist, was neuroprotective in these animal models. Moreover, the data show that the effect is mediated through alpha-2 adrenoceptors and involves, in part, the upregulation of antiapoptotic and neuronal survival genes.(AU)

Visual field in glaucoma

Documentation of glaucomatous damage is best determined by full threshold perimetry in conjunction with careful evaluation of the optic nerve's cupping and rim tissue. There is universal agreement of the earliest perimetric defects in progressive open angle glaucoma (POAG), although there is no "gold standard" for the perimetric documentation for progression of the established defects. The classical earliest lesions consist of nasal steps, relative paracentral scotomas within the central 20 degrees, and arcurate defects within Bjerrum's area. Documentation of deterioration of these defects is best achieved by specific software programmes now available (eg StatPac-2 and Progressor, Humphrey or the PeriData and PeriTrend, Octopus). These programmes evaluate the visual point-by-point basis so that follow-up fields can be compared to the initial baseline fields (two reliable fields before any therapy constitutes "baseline"). Progression is thereafter identified using pointwise linear regression of field sensitivity (dB) over time. A test location shows deterioration when a statistically significant change has occurred at that point (ie, there is a decrease of 1 dB centrally or of 2 dB at the periphery when the statistical significance (p < 0.05) using a two-tailed test has been achieved). It is, however, necessary that at least three reliable full threshold tests (30-2) have been obtained within 12 months before these assumptions can be made. The clinicians' therapeutic goal is the slowing or even reversal of established glaucomatous defects. Therefore, a glaucoma algorithm for the care of high risk patients (those under 50 years, those of African descent, and those with documented glaucomatous family history) will be described using present guidelines from the published primary treatment trials (AU)

Glaucoma in a general ophthalmic practice in Trinidad and Tobago

This study is a retrospective look at the records of all patients seen over a three-year period at two locations in Trinidad. There were more males (59 percent) than females; East Indians comprised 33 percent and Negroes 29 percent. 69 percent were self-referrals, optometrists referred 11 percent and general practitioners, 13 percent. Chronic open angle glaucoma was the most common diagnosis (55 percent) among patients presenting for the first time; glaucoma was suspected in 24 percent, narrow angle glaucoma in 10 percent.(AU)

Health status of the elderly in the Marigot Health District, Dominica

The health status and the prevalence of hypertension, diabetes mellitus, glaucoma and visual disorders of 123 elderly people (56 men, 67 women) in the Marigot Health District, Dominica, were assessed by means of four questionnaires: collection of data from their medical records; physical examination, measurement of blood pressure, visual acuity and intra-ocular pressure (IOP); and testing for glucosuria. The overall health status was good, but 20 percent were dependent on care. 74 percent were independent in the activities in daily life, with only moderate limitations in activities. The health status decreased considerably in those over 75 years of age. There were slight perceived differences in health status between men and women. About 40 percent of the study population were known to be hypertensive, and another 13 percent had an elevated blood pressure on examination. Diabetes mellitus was present in 15 percent. 20 percent had a visual acuity of 0.1 or below, and 10 percent had an elevated IOP. During the study, a considerable number of new cases of hypertension, diabetes mellitus and elevated IOP were diagnosed. 50 percent of the study population who were on medication used this more than as prescribed. This study indicates a high prevalence of the secondary complications of hypertension, diabetes mellitus, cataract, glaucoma and osteo-arthritis that cause disability and dependency in the elderly population. Education, diagnosis at an early stage and appropriate treatment of these disorders may prevent or delay their development. We suggest the development of a programme oriented approach of primary health care for the elderly to support this.(AU)

Central retinal vein occlusion: an important cause of blindness in glaucoma in the Negro

This study was designed to determine the frequency of central retinal vein occlusion as a cause of blindness in glaucoma. Glaucoma patients attending the author's practice over a four month period were examined specifically for evidence of central retinal vein occlusion (CRVO) and their visual acuity recorded. Evidence of CRVO was taken as the following: tortuous anastamotic vessels on the disc; scattered retinal haemorrhages; and telangiectatic retinal vessels or scattered cotton wool spots in the retina in the absence of other retinal disease, eg. diabetic retinopathy. Blindness was accepted as a best corrected visual acuity of 20/200 or worse. The cause of blindness was recorded. 74 blind eyes were recorded, with 44 (60 percent) blind from glaucoma, 22 (30 percent) blind from CRVO. All patients were predominantly Negro. Central retinal vein occlusion is a common cause of blindness in glaucoma patients who are black. This is an important and previously unrecognized fact. In this study approximately one-third of glaucoma patients were blind from CRVO and not glaucoma itself. Essential hypertension and glaucoma are associated factors in CRVO, and each of them has a high incidence in Negroes, and they may be acting synergistically to produce the high incidence of blindness due to CRVO found in this study. This also explains the increase severity of glaucoma in the Negro. Tissue under-perfusion in both diseases may be the underlying explanation.(AU)

Childhood blindness in Jamaica

Childhood blindness results in a lifetime of morbidity for the child and family involved, requiring special schooling with limited employment opportunities. The identification of the causes of blindness in children and their prevention, where possible, is of vital importance. We look at the causes of blindness in Jamaica. The leading preventable cause was congenital rubella syndrome, which often results in multiple handicap. This condition should be avoidable with a suitable immunisation programme. The leading treatable causes were congenital cataract and glucoma. These conditions may both be treatable if surgery is performed at an early age and specialist care is maintained.(AU)

The African Caribbean eye survey: risk factors for glaucoma in a sample of African Caribbean people living in London

The purpose of the study was to estimate the prevalence of and risk factors for chronic glaucoma in a sample of African Caribbean people over 35 years of age living in the London Borough of Haringey. A cross-sectional voluntary sample of persons were subjected to detailed ophthalmic assessment including automated tangent screen suprathreshold visual field testing, applanation tonometry and stereoscopic disc evaluation in 50 community-based survey clinics over an 8 month period. Cases and suspects were referred to Moorfields Eye Hospital for more detailed assessment and confirmation of the diagnosis. Of 873 eligible persons examined (out of a total of 1022), 32 definite cases of glaucoma were identified, a prevalence of 3.9 percent; 42 percent of these had been previously diagnosed. Approximately 10 percent of the sample required further assessment and follow-up when ocular hypertensives and glaucoma suspects were included. An age-standardised comparison with the findings of the Roscommon survey revealed a relative risk for glaucoma for Haringey blacks compared with Irish whites of 3.7. Significant risk factors for glaucoma included age, African birthplace and darker skin colour. Neither diabetes nor hypertension reached significance. Despite the lack of a population base, this study provides strong evidence that the 4 times greater risk of glaucoma estimated for American blacks compared with whites applies equally to the United Kingdom population. Community-based facilities are required to raise awareness of the risk among this ethnic minority in this country and case-finding resources should be provided to meet local needs (Summary)