Relationship between visual field loss and contrast threshold elevation in glaucoma.

BACKGROUND: There is a considerable body of literature which indicates that contrast thresholds for the detection of sinusoidal grating patterns are abnormally high in glaucoma, though just how these elevations are related to the location of visual field loss remains unknown. Our aim, therefore, has been to determine the relationship between contrast threshold elevation and visual field loss in corresponding regions of the peripheral visual field in glaucoma patients. METHODS: Contrast thresholds were measured in arcuate regions of the superior, inferior, nasal and temporal visual field in response to laser interference fringes presented in the Maxwellian view. The display consisted of vertical green stationary laser interference fringes of spatial frequency 1.0 c deg(-1) which appeared in a rotatable viewing area in the form of a truncated quadrant extending from 10 to 20 degrees from fixation which was marked with a central fixation light. Results were obtained from 36 normal control subjects in order to provide a normal reference for 21 glaucoma patients and 5 OHT (ocular hypertensive) patients for whom full clinical data, including Friedmann visual fields, had been obtained. RESULTS: Abnormally high contrast thresholds were identified in 20 out of 21 glaucoma patients and in 2 out of 5 OHT patients when compared with the 95% upper prediction limit for normal values from one eye of the 36 normal age-matched control subjects. Additionally, inter-ocular differences in contrast threshold were also abnormally high in 18 out of 20 glaucoma patients who had vision in both eyes compared with the 95% upper prediction limit. Correspondence between abnormally high contrast thresholds and visual field loss in the truncated quadrants was significant in 5 patients, borderline in 4 patients and absent in 9 patients. CONCLUSION: While the glaucoma patients tested in our study invariably had abnormally high contrast thresholds in one or more of the truncated quadrants in at least one eye, reasonable correspondence with the location of the visual field loss only occurred in half the patients studied. Hence, while contrast threshold elevations are indicative of glaucomatous damage to vision, they are providing a different assessment of visual function from conventional visual field tests.

Calcification of porcine valves: a successful new method of antimineralization.

Despite distinct advantages over mechanical cardiac valve prostheses, the use of bioprosthetic valves remains limited due to poor long-term durability, primarily as a result of tissue calcification. A novel anticalcification process, based on treatment of porcine bioprostheses with a derivative of oleic acid, has been developed by one of us (J.M.G.) (US Patent Number 4,976,733). This process employing 2-aminooleic acid (AOA) was tested in a juvenile sheep model. Terminal studies after a 20-week interval included hemodynamic, radiographic, morphologic, and quantitative tissue calcium analyses. All control valves (n = 4) had thickened, immobile, heavily calcified leaflets, whereas all AOA-treated valves (n = 8) were pliable and free of calcium deposits. Calculated valve orifice areas for controls (0.9 +/- 0.2 cm2) (mean +/- standard error of the mean) was less than for AOA-treated valves (2.0 +/- 0.3 cm2) (p less than 0.05). Radiographic calcification scores were greatly elevated in the control (25.5 +/- 5.6) versus AOA-treated valves (0.5 +/- 0.5) (p less than 0.002). In quantitative mineralization studies, the mean calcium content of the control leaflets was 129 +/- 21 milligrams per gram dry weight cusp tissue versus 7.7 +/- 5.8 mg/g for AOA-treated valves (p less than 0.001). Pathologic examination confirmed heavy calcification in the control leaflets, which was essentially absent in the AOA-treated leaflets. However, cuspal hematomas in areas of structural loosening and surface roughening were noted in AOA-treated valves. This anticalcification process dramatically reduced mineralization of porcine valve prostheses in this model.

Warm blood cardioplegia: superior protection after acute myocardial ischemia.

Three myocardial protection techniques were studied in a canine model of acute myocardial ischemia with subsequent revascularization. Eighteen animals were randomly assigned to one of three treatment regimens: cold oxygenated crystalloid cardioplegia (CC), cold blood cardioplegia with modified reperfusate (CB), and continuous aerobic warm blood cardioplegia (WB) (n = 6 per group). Systemic hypothermic cardiopulmonary bypass (28 degrees C), antegrade arrest, and intermittent retrograde and antegrade delivery were used for the CC and CB groups. Systemic normothermic cardiopulmonary bypass, antegrade arrest, and continuous retrograde delivery were used for the WB group. Fifteen minutes of warm global ischemia was followed by occlusion of the left anterior descending coronary artery (15-minute duration) and simultaneous initiation of cardioplegic arrest (60-minute duration) to simulate clinical revascularization. After reperfusion, the animals were separated from cardiopulmonary bypass. Myocardial function, electrocardiogram, myocardial energetics, water content, histopathology, and defibrillation requirements were compared between groups. There was no significant difference in maximum elastance, myocardial oxygen consumption, myocardial edema, or histopathologic evidence of injury between groups. However, overall ventricular function, assessed by the slope of the preload recruitable stroke work relationship, was significantly better for the WB group (p = 0.04) (WB, 73 +/- 9; CB, 56 +/- 7; CC, 47 +/- 5). Diastolic function as assessed by the slope of the stress-strain relationship was significantly worse overall for the cold groups (p = 0.001) (WB, 20 +/- 2.2; CB, 39 +/- 1.3; CC, 37 +/- 3.1). Myocardial injury as assessed by ST segment elevation (millimeters) was less for the WB group (p = 0.03) (WB, 0.4 +/- 0.3; CB, 1.7 +/- 0.2; CC, 1.6 +/- 0.7). Countershocks necessary to restore sinus rhythm after cross-clamp removal were fewer in the WB group (p = 0.03) (WB, 0.8 +/- 0.3; CB, 4.0 +/- 1.2; CC, 5.5 +/- 1.5). In this model of acute global myocardial ischemia, continuous aerobic warm blood cardioplegia has important advantages over two widely used clinical hypothermic protection techniques.

Clinical features and diagnosis of adult atopic keratoconjunctivitis and the effect of treatment with sodium cromoglycate.

This study describes 17 cases of atopic keratoconjunctivitis in adults. In 8 cases the clinical appearances were nonspecific and sufficiently different from vernal keratoconjunctivitis to make diagnosis difficult. These atypical cases often showed a fine papillary conjunctival reaction on the upper tarsus, subconjunctival scarring, and in 1 case severe symblepharon. Corneal features included corneal microcysts, peripheral vascularisation, and various patterns of punctate epithelial keratitis. It was therefore important to establish the atopic status of the patient. A personal or family history of other atopic disease was elicited in every case, and the diagnosis was confirmed by the detection of raised serum IgE level. Uncontrolled clinical assessment suggested that 10 out of 15 patients experienced improvement in symptoms with the use of 2% sodium cromoglycate eyedrops 4 times a day. A subsequent double-masked cross-over trial comparing the same treatment with a matched placebo preparation indicated that 6 out of 9 patients preferred sodium cromoglycate while 1 preferred the placebo. Two patients noted no difference. Cases showing nonspecific or atypical clinical features responded to treatment just as frequently as did cases of typical vernal keratoconjunctivitis.

Extracapsular lens extraction and posterior chamber intraocular lens insertion combined with trabeculectomy.

Trabeculectomy for primary glaucoma was successfully combined with extracapsular lens extraction and insertion of a Pearce tripod posterior chamber lens in seven eyes of five patients. The results were similar to those expected from each component of the operation when performed alone, and all eyes achieved visual acuity of 6/9 or better with control of intraocular pressure below 22 mmHg without supplementary medical treatment. The incidence of mild anterior uveitis (three out of seven eyes) and hyphaema (two out of seven eyes) was greater than usual with this type of cataract extraction but no more than expected after trabeculectomy. Mydriatic drops may be used to treat postoperative iritis without danger to the stability of this pattern of implant. In addition the anterior chamber cannot become shallow, as the rigid legs of this lens extend behind the iris beyond the periphery of the cornea and prevent forward movement of the implant even if there is excessively free drainage of aqueous after the operation.

The rate of visual field loss in untreated primary open angle glaucoma.

The mean rate of visual field loss in untreated primary open angle glaucoma was estimated by comparing the mean age at presentation of patients with early relative visual field loss with the mean age of those who presented with absolute field loss within five degrees of fixation. Analysis of the records of 177 patients indicated that the rate of field loss was related to the level of untreated intraocular pressure. For pressures of 21 to 25 mm Hg, untreated disease is likely to progress from early field changes to end stage in an average of 14.4 years. The same interval for pressures of 25 to 30 mm Hg was 6.5 years and for pressures over 30 mm Hg, 2.9 years. For untreated disease at pressures over 25 mm Hg the interval is estimated at 3.6 years and this is much shorter than the estimated period of 10 years under imperfect treatment and 38 years under optimum treatment identified in a prospective clinical trial of early trabeculectomy in patients with similar intraocular pressures at diagnosis.

Characteristics of reduction of intraocular pressure after trabeculectomy.

The change in intraocular pressure achieved after 98 trabeculectomy operations performed on 70 patients with primary open-angle glaucoma was analysed. The reduction was proportional to the untreated preoperative pressure, and the results indicated that a first trabeculectomy reduced the intraocular pressure to between 16 and 20 mmHg irrespective of its initial level. Cases which required medical therapy for final pressure control after surgery showed a distribution of initial intraocular pressure similar to those not requiring such therapy. In addition, these cases were reduced to a level of pressure only slightly above the arbitrary figure of 20 mmHg before medical therapy was added, and were therefore considered almost to have reached the normal physiological range. Cases submitted to a second trabeculectomy are discussed, including 2 cases with unexplained acute open-angle glaucoma some months after the first operation.

Effects of intraocular miotics on cultured bovine corneal endothelium.

Two cases of severe corneal oedema occurred after the use of intraocular pilocarpine. Experimental investigations were conducted with cultured bovine corneal endothelial cells exposed for 5 minutes to 1% pilocarpine solutions of varying composition. Cells were destroyed in solutions not isotonic with aqueous humour, and calcium-free ionic solutions caused loss of cell adhesion without loss of viability. Low pH or the presence of 1% pilocarpine had no detectable effects; 1% acetylcholine chloride in 5% mannitol (Miochol) also caused cell destruction, and this preparation was found to be considerably hypertonic. The minimum requirements for the formulation of intraocular miotics are discussed.

Age over 46 years does not affect the pressure lowering effect of trabeculectomy in primary open angle glaucoma.

BACKGROUND/AIMS: Previous reports have suggested that the success rate for trabeculectomy is poorer in younger age groups but these studies often have heterogeneous groups representing different types of glaucoma with variable surgical prognosis. Therefore, the relation between age and the success of trabeculectomy in the single diagnostic category of primary open angle glaucoma (POAG) without identifiable risk factors was examined for failure in the age range 46-85 years. METHODS: The records of 208 patients who had undergone a first trabeculectomy for POAG were examined retrospectively. Age ranged from 46 to 85 (mean 66.7 years). The outcome of surgery was examined at final available follow up and at 1 and 2 years after surgery. Trabeculectomy was considered a success if intraocular pressure was < or = 21 mm Hg with or without additional medical treatment ("cumulative" success) and an "absolute" success if intraocular pressure was < = 21 mm Hg without additional medical treatment. RESULTS: Cumulative success for trabeculectomy was 92.3% at final follow up and 96.6% at 2 year follow up; absolute success rate was 66.3% at final follow up and 71.6% at 2 years. There was no significant trend for greater success of trabeculectomy in the older age groups (cumulative success at 2 year follow up, chi 2 for linear trend 1.07 (p = 0.3) nor was the drop in intraocular pressure following surgery significantly greater with increasing age (analysis of variance for intraocular pressure lowering from presentation to 2 years' follow up (Kruskal-Wallis, t = 5.9, p = 0.55). Patients with pseudoexfoliation were excluded from the main analysis as these patients have been shown to have a lower final intraocular pressure following trabeculectomy, a finding which was confirmed in this study.

Early trabeculectomy versus conventional management in primary open angle glaucoma.

The results of a randomised, prospective, multicentre trial of the management of primary open angle glaucoma are presented at up to five years' follow up. Previously undiagnosed cases were selected with intraocular pressure of 26 mmHg or more on two occasions together with field loss characteristic of glaucoma. Analysis was performed on one eye selected at random from each of 99 patients. Conventional medical treatment followed in unsuccessful cases by trabeculectomy (group A) was compared with trabeculectomy at diagnosis followed when necessary by supplementary medical therapy (group B). The life expectancy of these glaucoma patients was found to be similar to that for the local population matched for age and sex. In group A after four years trabeculectomy had been performed in 53% of eyes because medical management had failed to control the disease. The rate of operation was lower in those patients with intraocular pressure less than 31 mmHg and mild relative field loss (17% at three years) than in those with intraocular pressure greater than 30 mmHg and dense scotomas (75% at three years). Early surgery provided much more stable control with fewer changes in treatment than in group A. The group mean intraocular pressure after trabeculectomy was 15.0 mmHg irrespective of the time of operation, and this was significantly lower than the intraocular pressure in those cases thought to be controlled on medical therapy alone at the end of the first year (20.8 mmHg). Early operation provided significantly better protection of visual field, and the extra loss of visual field with delayed operation occurred in the preoperative period. Changes in visual fields were not related to the use of miotics. There was no significant difference in the final visual acuity in the two groups, but six cases in group A lost central fixation because of progressive loss of visual field, and there were no such cases in group B. Cataract occurred in approximately 10% of cases in both groups, but in group A this happened with only half the number of operations and at a shorter postoperative follow-up than in group B. It appears that in cases of primary open angle glaucoma of this severity the risk of delaying operation are significantly greater than those of performing trabeculectomy as the primary treatment.

Dacryolith formation around an eyelash retained in the lacrimal sac.

A dacryolith was discovered in the lacrimal sac during a dacryocystorhinostomy for chronic dacryocystitis in which there was mucocele formation. Morphological examination confirmed the presence of an eyelash at the centre of the stone and electron microscopy demonstrated the presence of fungi (Candida sp.) in a matrix which was of markedly vairable morphology. The mechanism by which a hair enters the punctum and passes along the canaliculus may be attributed to the step-like pattern of ridges on the surface of a hair. The directional nature of these ridges dictates preferential movement towards the root end of the hair and prevents movements in the opposite direction.

The association of Fuchs's corneal endothelial dystrophy with axial hypermetropia, shallow anterior chamber, and angle closure glaucoma.

A series of 24 patients with Fuchs's dystrophy are presented in whom detailed clinical measurement showed an association with axial hypermetropia and shallow anterior chamber. In 14 of these patients one cornea had developed oedema, of which 11 had required penetrating keratoplasty. Comparison of these eyes with the fellow eyes without corneal oedema revealed that the anomalies in measurement were not due to the process of decompensation. These 14 patients were then compared with the remaining 10 patients without corneal oedema in either eye, and a similar profile of anomalous measurements was observed. The whole group of 24 patients were then compared with three separate control groups, and in each case a significant trend towards hypermetropia, short axial length, and shallow anterior chamber was noted. The mean spherical equivalent refractive error in the patients with Fuchs's dystrophy was +2.48 D compared with -0.31 D for controls; corresponding means for axial length were 22.1 mm compared with 23.4 mm; and for anterior chamber depth were 2.2 mm compared with 2.7 mm. Each of these differences was statistically significant, but there was no significant difference for the keratometry measurements between patients and controls. Five of 24 (21%) of the patients had problems related to shallow anterior chambers of whom 3 (12%) had manifest angle closure glaucoma requiring surgical peripheral iridectomy. The aetiology of Fuchs's dystrophy and of ametropia is discussed and possible modes of association outlined. This previously unrecognised association gives a rational basis for the widely accepted practice of combining penetrating keratoplasty with lens extraction and has several other practical implications which are important in the differential diagnosis and treatment of Fuchs's dystrophy and angle closure glaucoma.

Tissue response to aqueous drainage in a functioning Molteno implant.

The tissue reaction to a functioning Molteno implant has been studied by light microscopy and by scanning and transmission electron microscopy. The material was obtained from an aphakic 83-year-old human eye which required enucleation because of intractable bullous keratopathy, despite well controlled intraocular pressure. The tissue response around the silicone rubber tube was that of simple fibroblastic activity. Around the implant, however, there was fibrous tissue in which necrotic cell debris was prominent. No significant inflammation was observed in this tissue, but the choroid beneath the implant showed a focal inflammatory cell infiltrate. The morphology suggests that the tissue around all surfaces of the implant (450 mm2) is exposed to aqueous, which seems to have a toxic effect on the encapsulating connective tissue. The changes seen in the tissue exposed to draining aqueous are similar to those described in experimental studies of the effect of aqueous on cell growth in tissue culture.

Modification of trabeculectomy to avoid postoperative hyphaema. The 'guarded anterior fistula' operation.

The effect of varying the position of a trabeculectomy fistula on the rate of postoperative hyphaema was studied in a prospective randomised trial. One eye of each of 78 consecutive patients with primary open angle glaucoma and exfoliation glaucoma was allocated to one of two groups. In group A the fistula was fashioned anterior to the scleral spur, entirely in corneal tissue. In group B the fistula included cornea and sclera with trabecular meshwork and scleral spur. Seven out of 39 eyes (18%) in group A developed a postoperative hyphaema with detectable blood level, compared with 22 out of 39 eyes (56%) for group B (p less than 0.001). In addition, the severity of the bleeding was greater in group B, and the three cases of recurrent bleeding were all in this group. Group B patients remained in hospital for an average of 3.9 days, which was significantly longer (p = 0.004) than the average of 2.9 days for group A. This difference was related to the frequency and severity of the hyphaema. The type of dissection or the occurrence of hyphaema did not influence the intraocular pressure at 4 months after surgery.

Clinical evaluation of a multi-fixation campimeter for the detection of glaucomatous visual field loss.

The multi-fixation glaucoma screening chart, which uses the oculokinetic perimetry (OKP) technique, is a hand-held tangent screen with a central black test stimulus on a white background and a series of 26 numbered fixation targets arranged around the stimulus at various locations. When the numbers on the chart are read by the patient from 40 cm distance, the test stimulus passes through the relevant parts of the central visual field which are most vulnerable to glaucomatous damage. The test is positive (that is, abnormal) if at least one fixation number is associated with consistent disappearance of the stimulus. The OKP test was performed in 222 eyes of 126 glaucoma patients (aged 16-91 years) and 186 right eyes of 186 normal individuals (aged 19-86 years) using a 1.5 mm diameter stimulus. A further 144 eyes of 88 glaucoma patients (aged 60-85 years) and 31 right eyes of 31 normal individuals (aged 60-85 years) were tested with a 3 mm diameter stimulus. All eyes were also tested with conventional perimetry and the results of the conventional perimetry were categorised according to the Aulhorn-Karmeyer classification by four ophthalmologists without any knowledge of the OKP results. When the 1.5 mm stimulus was used, a true positive OKP result was obtained in 45% of eyes with relative scotomas, 81% of eyes with small absolute scotomas separate from the blind spot and 100% of eyes with more severe visual field defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Colour perception in pseudophakia.

Minor differences in colour perception between pseudophakic, phakic, and spectacle aphakic eyes were identified by the Pickford-Nicholson anomaloscope and the Farnsworth-Munsell 100-hue test. The results suggest that pseudophakic eyes are more sensitive to red and less sensitive to blue than aphakic eyes corrected with spectacles. Spectrophotometer measurements reveal that the Rayner-Pearce posterior chamber intraocular lens used in this study transmits an evenly balanced colour spectrum, whereas an aphakic spectacle lens exhibits significant colour distortion, reducing the red and enhancing the blue transmission. This distortion may possibly be attributed to the increased chromatic aberration in the spectacle lens compared with the intraocular lens.

Keratoconjunctivitis artefacta.

Six cases of keratoconjunctivitis caused by self-inflicted injury are described. The diagnosis is suggested by the combination of the characteristic sharply delineated lesions localised in the more accessible inferior and nasal quadrants of the bulbar conjunctiva and cornea, together with the unconcerned attitude of the patient and other psychological features. Secondary post-traumatic erosions, infections, and allergies may complicate the clinical appearances, and other functional eye disturbances including corneal anaesthesia may be detected. In all cases the eye condition resolved with a sympathetic but authoritative approach avoiding direct accusation. Avoidance of feelings about bereavement or sexual relationships were directly related to the onset of symptoms in 3 cases. In some patients the psychological mechanism seemed inaccessible and they continued to produce new self-inflicted diseases with considerable physical and psychological morbidity. These more intractable cases need psychiatric investigation but usually resist referral.

Effect of age on visual acuity after cataract extraction.

The best Snellen visual acuity in the three months after cataract extraction was found to decline with the age of the patient. The relationship was identical in 111 patients who had extracapsular extraction and a Pearce tripod posterior chamber intraocular lens and in 50 patients who had intracapsular extraction with spectacle correction. Vision after operation varied from a mean value of 6/5 at 50 years to 6/12 at 90 years, a decline of 1 line per 13.4 years. In the intracapsular group, over a mean follow-up period of 14 years, the rate of fall in acuity with increasing age after operation was found to be statistically similar to that of the early postoperative acuity plotted against age for both types of operation. This suggests that the rate of decline with age is unchanged after a prolonged period of aphakia with presumed increased exposure to ultraviolet and blue light. The data were found to be similar to the decline in the neurosensory elements of vision with age measured experimentally in 20 phakic subjects by laser interferometry. This method of assessment of contrast sensitivity threshold effectively bypasses changes in the optical media. The findings indicate that the previously recognised drop in visual acuity with age is not related to changes in the aging crystalline lens and support the view that there is a decline in the neurosensory elements of vision. It is important to recognise this deterioration so that results of surgery or other treatment are adjusted to allow for the age of the patients.

Quality of vision through diffractive bifocal intraocular lenses.

Two elderly women have each received a monofocal intraocular lens in one eye and a 3M diffractive bifocal intraocular lens in the other eye. Both eyes were shown to have equivalent retinal/neural function by measuring contrast sensitivity to laser interference fringes which bypassed refractive and other defects of the ocular media. The eyes with a bifocal intraocular lens displayed a much greater depth of focus, though at the expense of diminished contrast sensitivity compared with the normal values expected for that age. Simulation experiments suggested that the observed reduction in contrast sensitivity was not adequately explained by a simple reduction in retinal illumination of the in-focus image as might intuitively be expected from the bifocal separation of incident light to two simultaneous focal points. The simultaneous superimposition of the out-of-focus image on the in-focus image must also be considered, since this caused a significant reduction in contrast sensitivity when the retinal illumination was insufficiently above the photopic luminance threshold.

Effect of benzalkonium chloride on the stability of the precorneal tear film in rabbit and man.

Benzalkonium chloride, a surface-active preservative commonly used in eyedrop preparations, has been shown to hasten the drying of the precorneal tear film. In the rabbit, 0.01 per cent benzalkonium (the concentration usually employed as a preservative) shortened the time required for the appearance of dry spots on the corneal surface by a factor of about four. In man, an approximately twofold hastening was demonstrated. This effect is thought to preclude the use of this substance as a preservative in eyedrop preparations for use as local anaesthetics.