Does the site of filtration influence the medium to long term intraocular pressure control following microtrabeculectomy in low risk eyes?

AIMS: To evaluate the influence of varying surgical site on the medium to long term intraocular pressure (IOP) control in patients undergoing unenhanced small flap trabeculectomy (microtrabeculectomy) in eyes at low risk of failure. METHODS: A retrospective non-concurrent analysis was performed on two cohorts of patients who underwent unenhanced microtrabeculectomy at different sites by a single surgeon (SAV). The first cohort of eyes was part of a trial to study the astigmatic effect of microtrabeculectomy (results published elsewhere) and all had flaps centred at the 12 o'clock meridian (superior flaps). The second cohort consisted of eyes with flaps created on either side of the 12 o'clock-that is, superonasal in left eyes and superotemporal in right eyes. All case notes were reviewed for the preoperative and presenting IOPs, the number and duration of antiglaucoma medication use preoperatively and, postoperatively, any intraoperative, early, or late postoperative complications. All IOPs measured at 6 months and then yearly intervals were recorded. The baseline characteristics and IOPs at each follow up were compared between the eyes with the superonasal and superotemporal flaps of the non-12 o'clock group against those with superior flaps in the 12 o'clock group up to a maximum of 72 months. Survival was assessed by the site of microtrabeculectomy, with failure considered as any IOP above 22 and 15 mm Hg with or without medications. RESULTS: All patients had a minimum follow up of 12 months and 12/17 patients in the 12 o'clock group and 17/28 in the non-12 o'clock group completed the full follow up of 72 months. The IOPs at all points in time were lower in the left eyes with superonasal flaps compared to both the superior and the superotemporal groups. This difference was statistically significant between the three groups to the end of 4 years (p = 0.001) and remains clinically significant thereafter with the mean last recorded IOPs of 15.9, 12.4 (p = 0.03), and 14.3 mm Hg in the superior, superonasal and superotemporal groups respectively, with a smaller mean number of drops in the non-12 o'clock group. Kaplan-Meier curves showed a significantly better outcome for the cutoff IOP of 15 mm Hg in the superonasal group (p = 0.003) compared with both the other groups. CONCLUSION: Eyes with superonasal flaps achieve and maintain lower IOPs when compared with both the superior and superotemporal flaps. The results suggest that, when a low target IOP is desired, the site of surgery in an unenhanced filtering procedure should be superonasally sited.

Visual acuity and legal visual requirement to drive a passenger vehicle.

OBJECTIVES: (1). To test the consistency and ease with which number-plates of different component figures can be read under DVLA driving test conditions; (2). to test the relative difficulty of reading corresponding figures on registration plates of white and yellow backgrounds.Design Prospective study of consecutive eligible clinic patients. SETTING: Ophthalmology outpatients. SUBJECTS: 210 individuals with a corrected visual acuity with both eyes open of between 6/9 and 6/12. MAIN OUTCOME MEASURES: The ability to read three different number-plates under standard DVLA driving-test conditions (ie at 20.5 m in good daylight with glasses if worn) and the ability to read identical number-plates against a white and a yellow background. RESULTS: There is a significant difference between the ease with which three different number-plates can be read depending on their letter and numeral composition, although this did not seem to be significantly affected by whether they were printed on a yellow or white background. Only 92.3% of subjects could read all the number-plates at the legal distance, 96.7% could read at least one number-plate at the legal distance and 3.3% of the test subjects could not read any of the number-plates at 20.5 m. CONCLUSIONS: The current test protocol used to obtain a driving licence and, moreover, the test the police will employ to assess visual competence to drive, is highly variable and is unlikely to give consistent repeatable results. The performance of those with equally good visual acuity is unpredictable and is highly dependent on the number-plate they are asked to read. This variability could exclude some who would otherwise pass the test or pass an individual with a visual acuity below accepted standards. The forthcoming changes in the regulations for design of number-plates is an ideal opportunity to standardise the whole testing procedure for driving visual acuity.

Anatomical and visual outcome of retinal detachment surgery in children.

AIMS: To evaluate the visual and anatomical outcome, as well as complications following surgery, for rhegmatogenous retinal detachment in children at a tertiary referral centre over a 5 year period. METHODS: A retrospective survey of all children (aged 0-16 years) who underwent primary retinal detachment surgery at Queen's Medical Centre between April 1994 and March 1999. RESULTS: 15 consecutive patients were identified with a mean follow up of 14.7 months (range 3-57) and a mean age of 12.4 years. Trauma was the cause in 40% (6/15). Complete retinal reattachment was achieved in 86.6% (13/15). Visual improvement occurred in 53.3% (8/15), worsening of vision occurred in 13.3% (2/15), with no change in the remaining 33.3% (5/15). Visual acuity was D 6/12 in 6.6% (1/15) preoperatively, and 26.6% (4/15) postoperatively. CONCLUSIONS: Retinal detachment in children is rare compared with adults. There are therefore limited data available for this group of patients. These data provide one unit's experience over a 5 year period, and may help provide a basis for information for patients and their parents when discussing the risks and potential benefits of surgery for retinal detachment in the paediatric population.

Non-communication between ophthalmologists and optometrists.

Many patients seen in the British hospital eye service are referred by high-street optometrists; and, if the optometrist is to receive feedback from the ophthalmologist, the patient should consent to disclosure of medical information. On the referral form (revised GOS 18) there is a space for this purpose. We investigated the level of communication by asking optometrists in our hospital catchment area about their use of the GOS 18 form and by examining the medical records of all new patients seen in the eye outpatient department in one month. 79 optometrists (55%) returned the questionnaire. 54 routinely used the GOS 18; and, of these, 10 said they obtained patient consent always, 23 sometimes and 21 never. 158 of 555 sets of medical notes contained an optometrist's referral, 107 of them on the revised GOS 18; and patient consent had been recorded on 17 of these forms. Ophthalmologists responded to the optometrist in 2/17 (12%) cases where consent had been obtained and 15/90 (17%) where it had not. Ophthalmologists could provide much better feedback to optometrists. The GOS 18 form could be used more effectively; and there is no reason why patient consent to disclosure of medical information should not be obtained by ophthalmologists as well as by optometrists.

Pathogenesis of idiopathic scoliosis. The Nottingham concept.

There is no generally accepted scientific theory for the etiology of idiopathic scoliosis. Hence, current treatment is pragmatic and not based on knowledge of causation of the deformity. In Nottingham, we have evaluated data from studies of the hips, pelvis, spine, rib cage and trunk muscles in scoliotic (pre- and post operative) and control patients, cadavers and a mechanical model to formulate a new theory of etiology for idiopathic scoliosis (figs. 18 & 19 of ref. 15). Evidence is summarized for the view that idiopathic scoliosis results, in part, from a developmental abnormality in the central nervous system creating rib-vertebra angle asymmetry which leads to a cyclical failure of mechanisms of rotation control in the trunk; these involve rotation-inducing (pelvic) and rotation-defending (discal, ligamentous and costal) mechanisms acting mainly in gait. The mechanical breakdown of rotation occurs in association with a lateral spinal curvature and a lordotic segment to create the initial deformity of idiopathic scoliosis. Then, growth, both abnormal (secondary to vertebral hyper-pressures) and normal (linear spinal growth) with gravity adds to the initiating and continuing neuromuscular mechanisms to augment curve progression. This theory views the spine in the wider perspective of function in the trunk, evolution and development, all in relation to bipedalism. The goal of etiological research is ultimately to base a treatment on some knowledge of causation of the deformity.