Randomised, controlled trial of spirometric changes in elderly people receiving timolol or betaxolol as initial treatment for glaucoma.

AIM: To investigate respiratory and cardiovascular side effects in elderly people in the first 12 months after commencing topical beta antagonists. METHODS: 40 patients (mean age 74 years) were recruited to a randomised, masked study. Spirometry, pulse, and blood pressure were recorded before, 1 month, and 12 months after starting topical therapy with either timolol 0.5% twice daily or betaxolol 0.5% twice daily. RESULTS: After 1 month five of 20 patients allocated timolol and three of 20 given betaxolol had discontinued it for respiratory reasons, not always accompanied by symptoms. There were no significant differences in changes in mean values of spirometry, pulse, or blood pressure between groups. No further changes were made in therapy for respiratory reasons in the following year. One patient suffered a hypotensive stroke within 2 days of starting timolol. CONCLUSIONS: By performing spirometry before starting topical beta antagonist therapy and repeating it after 1 month most patients at risk of respiratory impairment can be identified.

Post-operative astigmatism control by selective suture removal.

Fifty eyes in 50 patients with > 2.5 dioptres (D) of with-the-rule astigmatism (refraction) following uncomplicated extracapsular cataract extraction were recruited for this prospective study. Selected single sutures were removed and both the amount of astigmatic loss and the change in axis were measured at intervals. After removal of the first suture the mean astigmatic loss at 1 week was 2.9 D by keratometry and the mean change in the axis was 23 degrees (74% occurred within the first hour). The astigmatic loss was greater with subsequent suture removal. Timing of suture removal (before or after 8 weeks) and the amount of initial post-operative astigmatism (more than or less than 5 D) had a minimal effect on the total astigmatic loss. We suggest selective single suture removal can be performed safely at 5-6 weeks post-operatively with removal of a second suture, if necessary, in the steepest axis after 1 hour. The prescription of spectacles should be delayed for 1 week after the final suture has been removed.

Avoiding unsuspected respiratory side-effects of topical timolol with cardioselective or sympathomimetic agents.

Topical timolol given for the treatment or chronic simple glaucoma may cause unrecognised bronchospasm among elderly people. We recruited 80 patients aged over 60 years, who were without a history of airways disease and already used timolol, into a randomised crossover study comparing the effects on spirometry and exercise tolerance of changing to betaxolol or dipivefrine therapy. Results showed an increase of 13% and 8% in mean peak flow rate and forced expiratory volume in 1 s (FEV1), respectively, when using betaxolol; and of 14% and 11% when using dipivefrine. There was also improved exercise tolerance with both agents. More than a quarter of the patients showed at least a 15% improvement in FEV1 when changed from timolol. Analysis of enrolment symptoms and response to nebulised salbutamol failed to produce a method of identifying these patients. Timolol may impair respiratory function and exercise tolerance of elderly patients even if they have no history of reversible airways disease.

Optical zone centration in keratorefractive surgery. Entrance pupil center, visual axis, coaxially sighted corneal reflex, or geometric corneal center?

PURPOSE: To study the differences in optical zone marking using the geometric corneal center, entrance pupil center, visual axis, and the coaxially sighted corneal reflex as centration points. METHODS: A modified autokeratometer was used to photograph the cornea in 50 volunteers under standardized levels of illumination, with the subject fixing on the keratometer target. These photographs enabled us to mark the above-mentioned centration points and measure the direction and degree of decentration. RESULTS: From the corneal intercept of the visual axis, the entrance pupil center was found up to 0.75 mm (mean, 0.34 mm) temporally, the corneal reflex was found up to 0.62 mm (mean, 0.02 mm) nasally, and the geometric corneal center was found up to 1.06 mm (mean, 0.55 mm) temporally. CONCLUSION: The ideal physiologic centration point is the corneal intercept of the visual axis. The decentration from the visual axis was least if the coaxially sighted corneal reflex was used for centration.

Optimal postoperative refraction for good unaided near and distance vision with monofocal intraocular lenses.

Forty five eyes with up to 2 dioptres of myopic astigmatism and up to 1 dioptre sphere either plus or minus following cataract extraction and implantation of a monofocal intraocular lens were examined to assess their unaided visual acuities. Forty three percent were able to see 6/12 and N8, and 60% were able to see 6/12 and N10. Subjects with between 1 and 2 dioptres of myopic astigmatism and virtually no sphere were able to see 6/12 and N10 in 82% of cases. This study confirms the benefits to both distance and near vision of myopic astigmatism as an alternative to multifocal intraocular lenses.

Intraocular lens power calculation--the selection of formula.

The postoperative refraction of the eye after intraocular lens (IOL) implantation is an important aspect of the quality of aphakia correction. The postoperative refraction cannot be guessed with consistent accuracy as the refractive power of an eye is multifactorial. Calculation of IOL power is based upon measurements of corneal curvature and axial length and an estimation of postoperative anterior chamber depth. There are a number of formulae available for the calculation of IOL power. The optical formulae, of which those of R. D. Binkhorst are the most popular, give results which are very similar and which all differ from the mathematical regression SRK formula by the indication of a stronger IOL power for short eyes. A statistical analysis of postoperative results confirms that the R. D. Binkhorst formula gives the author an over-powered IOL for short eyes when calculated for emmetropia but not when calculated for planned ametropia. Results with the R. D. Binkhorst formula will be improved by the modification of the anterior chamber depth according to the axial length. Both formulae give satisfactory results for the range of axial lengths commonly encountered in clinical practice. Whichever formula is used, it is important for each surgeon to analyse postoperative results and to modify the selection of IOL power according to this feedback to correct for consistent errors of instrumentation or technique.

The control of aniseikonia after intraocular lens implantation.

This paper reports a study of postoperative refraction and eikonometry of 50 patients who had unilateral cataract extraction with implantation of a pupil-supported intraocular lens. The mean postoperative aniseikonia (+/- SD) was 1.97 (+/- 1.82). A statistically significant relationship was shown between anisometropia and aniseikonia. Despite aniseikonia of up to 7.8 per cent there were no diplopia problems as the visual system exhibits a high degree of tolerance. It is concluded that aniseikonia can be controlled to within clinically acceptable limits by the simple calculation of intraocular lens power for isometropia.

Intraocular lens power calculation for planned ametropia: a clinical study.

A prospective series of 25 eyes received an intraocular lens (IOL) of power calculated for planned ametropia, by means of the formulae of R. D. Binkhorst, from data of axial length, corneal curvature, and postoperative anterior chamber depth. All the postoperative refractions were within the +/- 2 D range from the predicted refraction, confirming the clinical value of such calculation. A retrospective study of 100 eyes which had received a +19 D power Binkhorst IOL showed a wide range of change in refraction extending up to the +/- 6 D range, indicating that a 'standard' power IOL cannot be relied upon to reproduce the preoperative refraction. Calculation of IOL power from biometric data is essential when controlled postoperative ametropia is required.

The selection of intraocular lens power by calculation and by reference to the refraction--a clinical study.

Two hundred eyes each received a Rayner Binkhorst pupil-supported intraocular lens (IOL) after cataract extraction. One hundred received a standard power +19 D IOL and one hundred received an IOL of power calculated for emmetropia by the formula of R. D. Binkhorst using biometric data. Calculation reduced the incidence of postoperative refractive error greater than the +/- 2 D range from 20 per cent to 1 per cent virtually eliminating significant postoperative refractive error. Consideration of the preoperative refractions and the calculated IOL powers showed that there is no constant or reliable relationship. Twenty nine 'emmetropic' eyes were shown not to be 'normal' eyes but eyes with a wide range of axial lengths whose different optical components summated to give emmetropia. In the selection of IOL power, reference must be made to biometric data to allow for these optical components and for this reason IOL power cannot be determined from the preoperative refraction of the eye. The case for control of postoperative refraction by calculation of IOL power is a strong one and there appears little justification for the use of standard power IOLs with unpredictable refraction results.

Intraocular lens power calculation for emmetropia: a clinical study.

A series of 50 eyes received an intraocular lens (IOL) of power calculated for emmetropia from data of axial length, corneal curvature, and postoperative anterior chamber depth by R. D. Binkhorst's formulae. The postoperative refraction results were compared with those of 100 control eyes which received +19 D standard power IOLs without calculation. The calculated group had postoperative refractions which were closer to emmetropia, and the difference was os statistical significance, with 92% within the +/- 1D range and 98% within the +/- 2 D range from emmetropia. The calculated predictions of postoperative refraction were of a useful level of accuracy. Consideration of the sources of error indicates that there is no justification for the use of IOLs in power steps of less than 1 D. The calculation of IOL power allows the surgeon to control the postoperative refraction and avoid unwanted ametropia.

The computer calculation of intraocular lens power. A clinical study.

A series of forty eyes received intraocular lenses (IOLs) of power +17, +19, or +21 D after consideration of computer calculation based upon data of corneal curvature, axial length, and anterior chamber depth using the formula of R. D. Binkhorst. Results were compared with those of a control group of ninety eyes which were given IOLs of standard +19 D power. No difference was found between the resulting visual acuities or range of postoperative refractions. The preoperative refraction was found to offer no guide to the selection of IOL power. The results were analysed in detail and it was found that the computer prediction of postoperative refraction for the IOLs implanted was of a high level of accuracy. This suggests that improved clinical results are to be expected from a close adherence to the IOL power calculated by a system which has been tested for accuracy and reliability. The cautious minor adjustment of IOL power as in the protocol of this study does not influence the outcome.

Acute closed-angle glaucoma: an investigation into the effect of delay in treatment.

A retrospective study of 212 eyes with acute closed-angle glaucoma is reported. A peak incidence in the sixth decade was noted and an increased incidence in females confirmed statistically. A surprising and often marked delay occurred in the presentation of many patients for treatment, but visual outcome was not influenced by such delay. Despite good control of intraocular pressure, many of the eyes suffered visual loss from optic nerve damage, and the visual outcome was not related to the height of intraocular pressure at presentation. Damage to the visual system occurred very early in the disease, probably with the initial acute rise of intraocular pressure, and eyes appear to vary in their susceptibility to such an insult. It does not appear that earlier presentation of the patient with acute glaucoma would significantly improve the visual outcome in terms of visual acuity. The short critical time before damage occurs to the eyes suggests a role for preventive ophthalmology in the detection and surgery of eyes at risk with shallow anterior chambers and narrow angles before they develop acute closed-angle glaucoma.

Gentamicin penetration and decay in the human aqueous.

The penetration of gentamicin into human aqueous was measured after intensive drops or subconjunctival injection of the antibiotic. The drop regimen proved ineffective in producing a therapeutically effective level. After a single 40 mg subconjunctival injection an effective concentration was achieved in 2 hours and maintained for 24 hours. The significance of these findings is discussed with respect to therapeutic implications.

Association between acute glaucoma and the weather and sunspot activity.

The dates of presentation of 191 cases of acute closed-angle glaucoma which presented at the Birmingham and Midland Eye Hospital between 1971 and 1974 were analysed and the seasonal incidence of acute glaucoma confirmed (P less than 0-001). These data were compared with meteorological data for air temperature, rainfall, hours of sunshine, atmospheric pressure, cloud amount, terrestrial magnetic field level, and sunspot numbers. A statistically significant direct association (P less than 0-05) was found with hours of sunshine and an inverse association (P greater than 0-05) with cloud amount. A statistically significant inverse association (P less than 0-05) was found with sunspot count, and this assumed high significance (P less than 0-0005) on consideration of sunspot activity in the preceding period. The literature is reviewed and the significance of these findings discussed.

Management of chronic glaucoma with pilocarpine Ocuserts.

This paper presents a clinical assessment of the Ocusert pilocarpine therapeutic system in 22 patients. Severe patients were 'wearing failures' and one was a 'therapeutic failure'. In the remaining patients intraocular pressure were controlled satisfactorily by a small daily dose of pilocarpine and there was relief from the burden of regular drop administration and the transient myopia which follows each instillation. This study confirms a place for the 'Ocusert' system in the management of some patients with chronic glaucoma.

Complete avulsion of the optic nerve. A clinical, angiographic, and electrodiagnostic study.

A case of traumatic complete avulsion of the optic nerve is reported together with fluorescein angiography and electrodiagnostic findings. Despite the disappearance of the central vessels, circulation remained in the branch retinal vessels and angiography demonstrated communication between peripapillary choroidal vessels and the superior temporal artery. The visually-evoked cortical response was abolished. Electroretinography showed a normal a-wave but reduced amplitude b-wave, not supporting the theory of the existence of centrifugal retino-suppressive fibres in the optic nerve of man.