The rates of blindness and of partial sight registration in glaucoma patients.

PURPOSE: To determine the extent of unregistered blind and partial sight visual loss amongst primary open angle glaucoma (POAG) patients in an outpatient clinic. METHODS: A 13 year follow-up study was carried out of all patients with POAG attending the outpatient clinics at the Leicester Royal Infirmary during the first 4 months of 1982. RESULTS: Ninety (35%) of 258 patients achieved eligibility for registration and 47 patients (18%) were registered, consisting of 39 who were eligible and 8 who were not. Fifty-seven per cent of eligible patients remained unregistered. Patients with visual loss due to visual acuity loss were much more likely to be registered than patients with either visual field loss (p < 0.001) or mixed visual acuity/visual field loss (p < 0.001). All categories of eligible patients experienced a delay between eligibility and registration. This delay was much longer for the visual field loss patients (median delay 61.8 months). Patients with untreatable disease were more likely to be registered. The rates of registration are improving. CONCLUSION: A large proportion of glaucoma patients who are eligible for registration as either blind or partially sighted remain unregistered. Those who are registered often experience prolonged delays before becoming registered.

Course and complications of intermediate uveitis.

Intermediate uveitis is associated with a wide variety of complications, particularly in patients attending uveitis referral centres, but little information exists on the frequency of these complications in a general pool of patients. We reviewed all the cases known to have originated in one English county. 86 eyes of 48 patients with a mean follow-up of 48 months were affected. The principal threat to sight was cystoid macular oedema (31%). Other complications included vitreous haemorrhage (8%), disc swelling (5%), periphlebitis (21%) and cataract (5%). Most patients required no treatment other than observation and overall the visual outcome was good with 85% of patients and 63% of eyes having vision of 6/9 or better. Cystoid macular oedema and snowbanking were significantly associated with a worse visual outcome, whilst the other complications were not.

Prevalence of age-related maculopathy at two points in time in an elderly British population.

UNLABELLED: As the demography of Western society changes, the population prevalence of diseases such as age-related macular degeneration (AMD) is expected to rise. Despite this, there remains a paucity of quality data concerning the population prevalence of AMD, the commonest cause of blindness in the elderly. PURPOSE: To report the prevalence of AMD at two points in time in an elderly population. METHOD: A geographically defined random population sample of elderly people was defined in 1980, and studied in 1982-4. In 1990, a cohort of survivors was identified. Participants underwent full ophthalmic examination with fundus photography using the same camera on each occasion. Photographs were randomly encoded and graded by two independent masked observers using the Wisconsin Age-related Maculopathy Grading System. Disagreements were resolved by consensus. RESULTS: Eighty-eight survivors participated in the follow-up examinations. Of these, 82 subjects had gradable retinal photographs for both examination points in at least one eye. There were 158 pairs of images (initial and subsequent) available for analysis. The mean age was 80 years (range 77-90 years) at the initial examination, and 87 years (range 84-97 years) at the subsequent examination; 70.7% of subjects were female. Prevalence rates for the initial examination were: drusen 72.8%, drusen confluence 37.3%, degeneration of the retinal pigment epithelium (RPE) 51.3%, increased pigment 22.2%, exudative AMD 1.9% and geographic atrophy 1.9%. Rates at second examination were: drusen 62.7% drusen confluence 41.8%, RPE degeneration 72.8%, increased pigment 16.5%, exudative AMD 3.8% and geographic atrophy 3.2%. CONCLUSION: This 'double' prevalence study provides detailed data on AMD lesions at two points in time in a population-based group of elderly people.

Seven year follow-up of age-related maculopathy in an elderly British population.

UNLABELLED: Despite age-related macular degeneration (AMD) being the commonest cause of blindness amongst the elderly in Western society, the incidence of new lesions is poorly documented and the natural history of existing disease remains ill understood. PURPOSE: To document in an elderly population the incidence of new AMD lesions and the progression of pre-existing AMD over time. METHOD: Baseline ophthalmic examinations were performed on a geographically defined random population sample of elderly people in 1982-4, and retinal photographs taken. The present study re-examined and re-photographed survivors after approximately 7 years using the same fundus camera. Photographs were randomly encoded, and independently graded for AMD features by two masked observers using the Wisconsin AMD grading system. Disagreements were resolved by review to reach a consensus. RESULTS: Eighty-two of the 88 participating survivors had photographs of gradable quality on both occasions in at least one eye. Mean age at follow-up was 87 years (range 84-97 years) and 70.7% of subjects were female. Paired photographs were available on 158 eyes, and showed important differences in drusen type, drusen area and characteristics of the retinal pigment epithelium (RPE) between initial and subsequent examinations. The 7 year incidence (and regression) of lesions was: drusen 30.6% (20.0%), RPE degeneration 54.5% (8.8%), increased pigment 11.6% (64.7%), subretinal haemorrhage 1.3%, subretinal scar/fibrin 1.3% and geographic study 1.3%. CONCLUSION: These unique population-based results provide new insight into the natural history of AMD in an elderly population.

LOCS III versus the Oxford Clinical Cataract Classification and Grading System for the assessment of nuclear, cortical and posterior subcapsular cataract.

PURPOSE: To compare two methods of cataract grading for nuclear cataract, cortical cataract and posterior subcapsular cataract. METHODS: The Melton Eye Study is an English community-based epidemiological study of the natural history of eye disease in people aged 55 to 74 years. The lenses of both eyes of 560 subjects were graded at the slit lamp using two cataract grading systems. The Oxford Clinical Cataract Classification and Grading System (OCCCGS) employs standard diagrams and Munsell colour samples for the grading of cortical, posterior subcapsular and nuclear cataract. The Lens Opacities Classification System III (LOCS III) uses photographic transparencies of the lens as standards. In both systems a decimalised score is assigned. We also graded the LOCS III standard images using the OCCCGS. Interobserver variation was calculated for both grading systems. Linear calibration lines are plotted for each type of lens opacity. RESULTS: The relationship between LOCS III and OCCCGS for nuclear cataract and posterior subcapsular cataract is linear. The relationship for cortical cataract is linear once the LOCS III scores are squared. The intervals between the LOCS III images when ranked by the human eye using the OCCCGS are linear. Interobserver variation for both systems is good. CONCLUSIONS: The linear calibration lines may be used to convert from one system to another and will be useful in comparing studies or performing meta-analysis. These results show that data from cataract studies using different clinical grading schemes can be compared.

Prevalence of lenticular abnormalities in a population-based study: Oxford Clinical Cataract Grading in the Melton Eye Study.

PURPOSE: To describe the distribution of the 11 features assessed by the Oxford Clinical Cataract Classification and Grading System (OCCCGS) in a population-based study. METHODS: The Melton Eye Study is an English community-based epidemiological study of the natural history of eye disease in people aged 55 to 74 years. Both lenses of 560 subjects were graded at the slit lamp using a decimalised version of the OCCCGS. Subject prevalences were estimated by logistic regression and the extent, when present, against normal errors regression. RESULTS: White nuclear scatter (WNS), brunescence, cortical spoke (CS), anterior subcapsular opacity (ASC), fibre folds (FF), waterclefts (WC) and perinuclear retro-dots all increased with age (p < 0.05). Posterior subcapsular opacity (PSC), vacuoles, focal dots (FD) and coronary flakes (CF) did not significantly increase with age. Subject prevalences of the features and the mean Oxford scores when present were: WNS (1.33), brunescence (0.88), CS 36% (0.34), PSC 11% (0.52), ASC 2% (0.53), FF 18% (0.53), WC 17% (0.29), retro-dots 11% (1.15), vacuoles 59% (0.43), FD 98% (1.79) and CF 39% (1.24). Significantly more common in women were both coronary flakes (p < 0.001) and waterclefts (p < 0.05). CONCLUSIONS: These are the first data on the distribution of these minor lesions in a population-based study. Coronary flakes and waterclefts are more common in women.

Associations between lens features assessed in the Oxford Clinical Cataract Classification and Grading System.

PURPOSE: To study the associations between eleven lens features graded according to the Oxford Clinical Cataract Classification and Grading System (OCCCGS). METHOD: 560 subjects taking part in the Melton Eye Study had their lenses graded according to the OCCCGS by one of two examiners. Associations between features were examined using log-linear models for categorised grades. Adjustment was made for age, sex and grader. RESULTS: Within subjects, the two nuclear features, white nuclear scatter and brunescence, are closely related with one another, as are coronary flakes and focal-dots, but these two groupings are negatively associated. Cortical spoke, fibrefolds and waterclefts are all associated with one another and this group is positively associated with coronary flakes and focal-dots. Posterior subcapsular and anterior subcapsular opacity are associated with one another and with cortical spokes. A within-eye analysis gives similar results. CONCLUSION: These associations may be important in defining cataract subtypes and in identifying minor features that indicate early cataract development.

A uveitis register at the Leicester Royal Infirmary.

In the study of uveitis, epidemiology is frequently neglected. Our uveitis register consisted of data collected on all uveitis patients except minor, easily resolved, anterior uveitis cases at the Leicester Royal Infirmary. The diagnoses of these patients were classified by the aetiological method. A total of 712 patients was entered into the register over a period of 10 years starting from January 1985. In the study, 73.0% of the cases fit into named clinical syndromes while 27.0% of the cases were diagnosed as idiopathic but uncategorised. The commonest definable cause of anterior uveitis was HLA-B27-related acute anterior uveitis, comprising 15.2% of all uveitis cases. Intermediate uveitis accounted for 7.9% of all cases while the commonest definable cause of posterior uveitis was toxoplasmosis, forming 4.6% of all uveitis cases. The aim of the study was to present data relating to diagnostic categories from a primary and secondary uveitis clinic, and to explore the usefulness of such a uveitis register within an ophthalmic department.

A cross-over trial comparing once daily levobunolol with once and twice daily timolol.

The intraocular pressure (IOP) lowering efficacy of once-daily levobunolol 0.5% was compared with timolol 0.5% twice-daily and timolol 0.5% once-daily in 20 chronic open angle glaucoma and 5 ocular hypertensive patients. The design used was a randomised double blind cross-over trial with three periods each of 8 weeks separated by 2 weeks of no treatment. We found that following levobunolol a two week washout was not sufficient for the IOP to return to its original baseline level suggesting that levobunolol is a longer acting drug than timolol. Adjusting for this carryover effect, we found on significant difference in the IOP lowering effect among the three regimes (p = 0.53). Reduced cost, less ocular discomfort and better compliance are the main potential advantages of the once daily treatments.

Fuchs' heterochromic iridocyclitis revisited.

Fuchs' heterochromic iridocyclitis is an unusual form of uveitis of unknown aetiology that continues to be poorly understood and underdiagnosed. We present the clinical features observed in 77 patients (89 eyes) seen in the Uveitis Clinic at Leicester Royal Infirmary over a 2-year period. The most common presenting symptom was visual deterioration (96.1%) rather than pain (18.2%). Only 50.6% were diagnosed as Fuchs' heterochromic iridocyclitis at presentation. At review, clinical heterochromic iridum was observed in 70.1% and 15.6% were bilateral. Lens opacities were seen in 73.0%, 40.4% (of the total) having undergone cataract surgery. Glaucoma was diagnosed in 15.7% at presentation and in 21.3% at review, by which time 9.0% (of the total) had required filtration surgery. It is important that Fuchs' heterochromic iridocyclitis is diagnosed correctly since, although many patients do not require active treatment, all should be screened at regular intervals for glaucoma.

Vitreous loss in planned extracapsular cataract extraction does lead to a poorer visual outcome.

Forty-six cases of vitreous loss during planned extracapsular cataract extraction salvaged by anterior vitrectomy and primary anterior chamber lens implantation were compared in a retrospective cohort study with 92 individually matched controls. The postoperative visual outcome for cases with vitreous loss was significantly poorer than that for controls even after adjustment for confounding variables. Part of this visual morbidity was explained by cystoid macular oedema and retinal detachment, but even after adjusting for these two complications visual outcome remained worse among cases than controls. There was a significantly higher incidence of clinically apparent cystoid macular oedema amongst cases compared with controls (20% versus 1%). Two retinal detachments occurred among the cases but this difference in incidence was not statistically significant.

Applications of epidemiological techniques.

Epidemiology is the study of disease occurrence in human populations. Its methodology could be used in health services research and medical audit. In fact, most ophthalmologists today should be using some form of epidemiological technique to evaluate their own practice and the service they are providing for their patients.

The prevalence of eye disease in Leicester: a comparison of adults of Asian and European descent.

Random samples of people aged 40 years and over were drawn from lists of patients registered with two neighbouring inner-city general practices: one predominantly with Asian patients and the other predominantly with European patients. The people selected were invited to attend specially arranged eye clinics for examination by an ophthalmologist and an optician. We examined 377 people and found that, compared to people of European descent, Asians had a significantly higher prevalence of age-related cataract: 30% compared to 3% in people aged under 60 years and 78% compared to 54% in those aged 60 years and over. The age of onset of cataract seems to be earlier in Asians. After adjustment for age, there were no statistically significant ethnic differences in the prevalences of open-angle glaucoma, macular degeneration or diabetic retinopathy.

An analysis of referral routes and diagnostic accuracy in cases of suspected glaucoma.

Over a nine-month period two hundred and thirteen referrals to the Department of Ophthalmology of the Leicester Royal Infirmary, England, for suspicion of glaucoma were examined by a single ophthalmologist. Ninety-nine percent of referrals resulted from the findings at an optometric visit. Despite this, less than 32% were confirmed as having glaucoma and less than 23% had ocular hypertension. Twenty-nine percent showed no abnormality. Of those with glaucoma 19% showed advanced field loss in their worse eye. The guidelines relating to referral practices as a result of optometric examinations need to be reviewed and agreed upon by ophthalmologists, optometrists and general practitioners.