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)

Longitudinal changes in IOP and incident glaucoma in the Barbados Eye Studies

PURPOSE: There are a few longitudinal population studies describing the progression of intraocular pressure (IOP) or the risk of developing incident open-angle glaucoma (OAG). This report examines changes in IOP and measures the incidence of IOG over a 4-year period in the population of the Barbados Eye Studies. METHODS: The Barbados Incidence Study of Eye Disease (BISED) re-examined members of the Barbados Eye Study (BES) cohort, the original sample being based on a simple random sample of the country's population aged 40 - 84 years. At both visits patients had applanation tonometry, automated Humphrey perimetry, a comprehensive opthalmological examination, colour stereo fundus photography, blood pressure and anthropometric measurements and a detailed interview. RESULTS: A total of 3427 participants or 85 percent of the eligible cohort were re-examined in BISED. The IOP analyses were based on the subset of 2640 Black participants without glaucoma (OAG, or other type) or history of IOP lowering treatment at either visit. The mean age at follow-up was 55 years and 60 percent were women. Mean IOP was 17.3 mmHg (SDñ3.0, median 17.0) at baseline and increased by 2.6 mmHg (SDñ3.6 mmHg, median 2.3)(p<0.001by paired 1 test) in 4 years. Factors positively associated with longitudinal increases in IOP include age (p=0.001) and baseline hypertension (p=0.014) or high systolic blood pressure(p=0.005), while there was an inverse association with baseline IOP. Among the 2989 Black participants without OAG at baseline,the 4-year incidence of OAG was 2.2 percent (95 percent CI: 1.7 percent, 2.8 percent). Incidence was highest among persons classified as suspect OAG at baseline (26.1 percent) followed by ocular hypertensives with IOP >21 mmHg (4.9 percent) and lowest in persons with normal / other diagnoses and with IOP ó21 mmHg (0.8 percent). However, 32 of the 67 new cases of OAG (48 percent) had IOP ó21 at baseline. CONCLUSION: Significant increases in IOP were seen at 4-year follow-up in persons without glaucoma or IOP-lowering treatment history. While high IOP increases the risk of OAG, almost half of the incident cases had IOPó21mmHg at baseline. These results highlight the importance of prognostic factors, other than IOP, in determining the development of OAG.(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)

Masquerade? A case of central retinal vein occlusion

Central retinal vein occlusion is one of the most common retinal diseases seen in clinical practice, ranking second only to diabetes as a cause of catastrophic retinal vascular disease. Recognition of the risk factors for this disease is of particular importance because the complications are a cause of significant visual morbidity. Systemic hypertension and open angle glaucoma are well known associated conditions. Several biochemical factors have been implicated as risk factors, including elevated lipid and cholesterol concentrations, and the presence of antiphospholipid antibodies. Systemic diseases resulting in hyperviscosity such as polycythaemia and Waldenstrom's macroglobulinaemia can cause central retinal vein occlusion. A case study of a 48 year old female who developed prethrombotic central vein occlusion, present on waking on at least three occasions, was investigated. Full cardiovascular investigations and exhaustive haematological screening were negative. However, the patient had a well documented history of snoring and sleep apnea. This was confirmed by polysomnography. Anticoagulation with coumadin led to resolution of the condition on two occasions, but the patient discontinued therapy and suffered a full-blown vein occlusion. This case suggests that obstructive sleep apnea may be one of the predisposing factors for occlusive retinal vein disease. Further improved understanding of the medical conditions associated with this disease may have implications for the patient's general well being (AU)