The effect of pupil dilation with tropicamide on vision and driving simulator performance.

PURPOSE: To assess the effect of pupil dilation on vision and driving ability. METHODS: A series of tests on various parameters of visual function and driving simulator performance were performed on 12 healthy drivers, before and after pupil dilation using guttae tropicamide 1%. A driving simulator (Transport Research Laboratory) was used to measure reaction time (RT), speed maintenance and steering accuracy. Tests of basic visual function included high- and low-contrast visual acuity (HCVA and LCVA), Pelli-Robson contrast threshold (CT) and Goldmann perimetry (FIELDS). Useful Field of View (UFOV--a test of visual attention) was also undertaken. The mean differences in the pre- and post-dilatation measurements were tested for statistical significance at the 95% level using one-tail paired t-tests. RESULTS: Pupillary dilation resulted in a statistically significant deterioration in CT and HCVA only. Five of 12 drivers also exhibited deterioration in LCVA, CT and RT. Little evidence emerged for deterioration in FIELDS and UFOV. Also, 7 of 12 drivers appeared to adjust their driving behaviour by reducing their speed on the driving simulator, leading to improved steering accuracy. CONCLUSIONS: Pupillary dilation may lead to a decrease in vision and daylight driving performance in young people. A larger study, including a broader spectrum of subjects, is warranted before guidelines can be recommended.

Biometry of the silicone oil-filled eye.

PURPOSE: The advent of silicone oil tamponade has resulted in improved success rates in complicated retinal detachment surgery. Its use, however, can induce cataract formation in phakic eyes. In selected patients, removal of silicone oil can be combined with phacoemulsification of the cataract and intraocular lens (IOL) implantation, thus avoiding a further operation. This, however, poses a problem when trying to decide the power of IOL to be used, since the echographically measured axial length (AL) of an eye is greater in the presence of silicone oil. We performed ultrasound examination in the presence of silicone oil of viscosity 1300 centistokes, in order to determine whether the measured AL varied from the true AL by a constant factor. METHODS: The ALs of 7 phakic eyes were measured by A-mode echography, with and without silicone oil of viscosity 1300 centistokes in the posterior segment. The retina was attached in all cases. The control group consisted of 6 phakic eyes with attached retinae undergoing vitrectomy without the use of silicone oil. The ALs in the control group were measured before and after vitrectomy. RESULTS: The mean ratio of true AL to measured AL in the presence of silicone oil was 0.71 (standard deviation 0.01; range 0.70-0.73; median 0.71) in the 7 eyes in this study. In the control group, vitrectomy appeared to have no significant effect on AL. CONCLUSIONS: We have established a constant which corrects for the apparent increase in AL induced by silicone oil of viscosity 1300 centistokes. This conversion factor, when used in existing biometry formulae (SRK/T), allows estimation of the power of IOL required in eyes undergoing combined cataract extraction, removal of silicone oil and lens implantation.

Trabeculectomy augmented with mitomycin C application under the scleral flap.

AIM: The authors investigated the safety and intraocular pressure (IOP) lowering effectiveness of trabeculectomy augmented with mitomycin C application beneath the scleral flap, and assessed the influence of preoperative risk factors on the surgical outcome. METHODS: A retrospective study of 72 consecutive high risk eyes undergoing trabeculectomy with adjunctive mitomycin C (0.2 mg/ml) applied under the scleral flap for 5 minutes was performed. Each eye was ascribed a score based on the number of preoperative risk factors, and categorised into one of three risk factor groups. Success was described as unqualified where IOP was < or = 21 mm Hg without medication and qualified where antiglaucomatous therapy was required to maintain it at such a level. A life table analysis of IOP control was calculated. RESULTS: The mean IOP (SD) fell from a preoperative level of 28.4 (6.9) to a level of 16.63 (8.06) mm Hg at the last follow up (paired Student's t test: p < 0.0001). Fifty two eyes (72%) were classed as unqualified successes. The survival rates did not differ significantly between different risk factor groups (log rank test: chi 2 = 0.967, p > 0.1). The incidence of postoperative complications compared favourably with reports of mitomycin C application between Tenon's capsule and the undissected scleral bed. CONCLUSION: The results illustrate that mitomycin C applied beneath the scleral flap during trabeculectomy in high risk eyes is associated with a success rate comparable to other modes of application. The incidence of potentially serious complications such as conjunctival wound leak and prolonged hypotony was lower than previously published data reporting sub-Tenon's administration of mitomycin C. The number and nature of preoperative risk factors do not appear to influence the surgical outcome. A possible mechanism of action is proposed.

Carotid artery Doppler ultrasonography in retinal macroaneurysms.

It is postulated that retinal arterial macroaneurysms (RAMs) occur at the site of incomplete embolic occlusion of a branch retinal artery. Embolic events of the retinal vessels are related to the state of the carotid artery tree and therefore Doppler ultrasonography of the carotid arteries in these patients is of particular interest. We have examined 13 patients with retinal artery macroaneurysms with carotid artery Doppler ultrasonography (CADU). Eight of these patients (61.5%) exhibited atheromatous plaques on the same side as the RAM with a moderate degree of arterial narrowing. Although our group of patients did not show advanced carotid artery disease, alterations of the arterial wall found at the level of the carotid artery were higher than expected in a similar hypertensive population. To our knowledge this is the first study of the carotid arterial tree in these patients. Our results support the theory that RAMs may be of embolic origin. Furthermore they demonstrate that CADU is a useful investigation in patients with RAMs.

Astigmatism decay immediately following suture removal.

In a prospective study of 34 patients with high post-operative astigmatism (mean 6.90 D, range 2.75-15.00 D) following extracapsular cataract surgery (13 limbal sections and 21 corneal sections), we used keratometry to assess the changes in corneal curvature seen within 30 minutes of suture removal and compared these with the astigmatism found 2 weeks later. The greatest change occurred within the first 5 minutes of suture removal (mean 3.63 D; 95% confidence interval (95% CI) 2.85-4.41). The rate of decay then declined so that between 15 and 30 minutes the mean change was 0.56 D (95% CI 0.43-0.69). At 2 weeks a further mean decay of 1.29 D (95% CI 0.99-1.61) occurred. Of the 6 patients exhibiting a residual astigmatism greater than 3.00 D at 30 minutes, 4 continued to do so 2 weeks later. Our study suggests that keratometry 30 minutes following suture removal is only moderately different from that seen 2 weeks later. Although not stable enough to suggest that patients could be routinely refracted within 30 minutes of suture removal, in cases where early visual recovery is essential, such as in monocular patients, it may be reasonable to offer a temporary spectacle correction immediately following suture removal. Furthermore keratometry at 30 minutes after suture removal accurately predicts the necessity for further removal of sutures and indicates which patients can be discharged to the care of their own optometrist, making a further hospital visit unnecessary.

Phacoemulsification versus endocapsular cataract extraction in a unique cohort of patients.

The visual recovery and refractive results of 33 consecutive patients (66 eyes) undergoing standard endocapsular cataract extraction in one eye and simultaneous phacoemulsification in the fellow eye are reported. One surgeon performed all the operations. Surgically induced astigmatism was evaluated for the two techniques in terms of: (1) the proportion of eyes with a refractive cylinder of 1.5 dioptres (D) or less; (2) the interocular difference in post-operative astigmatism. Eyes undergoing phacoemulsification had a significantly lower mean induced cylinder (paired Student's t-test: t = 3.729; p < 0.001) and were more likely to exhibit a cylinder of 1.5 D or less (chi-squared test with Yates' correction: chi 2 = 7.88; p < 0.01) than the nuclear expression group. For paired eyes less post-operative astigmatism (Wilcoxon's signed rank test: T = 92; p < 0.01) was seen in the phacoemulsification eye. At the time of the last post-operative assessment a significantly higher proportion of phacoemulsified eyes achieved a corrected Snellen visual acuity of 6/6 or better than their fellow eyes (McNemar's test: p < 0.01). The results of this unique cohort of patients confirm the beneficial effects of phacoemulsification on astigmatism and visual outcome in the early post-operative period.

Non-attendance at ophthalmology outpatient clinics.

Non-attendance at outpatient clinics is a common problem, resulting in inefficiency and wasted resources. To establish the reasons why patients failed to attend their outpatient clinic appointment and to assess what proportion of these failed attendances were potentially preventable, we conducted a 13-month prospective postal survey of clinic non-attenders to our hospital. Of 5248 appointments made during the study, 521 were not kept (9.9%). Of these, 224 patients replied to the questionnaire, a response rate of 43%, with new patients more likely to not attend than old patients (odds ratio 2.7, P < 0.001). From the replies, 27.3% of non-attendances could be described as 'clerical error' with a further 17.9% due to patients failing to remember their appointment. Based on the replies received, a better organized outpatient booking system and a simple postal reminder could potentially prevent at least 40% of non-attendances.

Angle closure glaucoma in Alagille syndrome. A case report.

Alagille's syndrome or arteriohepatic dysplasia is a unique and uncommon congenital disorder exhibiting a combination of systemic and ocular abnormalities. It is of interest to the ophthalmologist presenting with a combination of anterior and posterior segment anomalies and it is unique for the paediatrician in that these anomalies distinguish this condition from all other causes of neonatal jaundice. The authors describe a case of a young girl with Alagille's syndrome who developed bilateral acute angle closure, a hitherto unreported finding in this condition.

Extensive visual loss with topical facial steroids.

Steroid creams applied topically to the skin are routinely used in the treatment of many dermatoses. Their use on the face in severe atopic eczema is relatively common. We report a series of three patients who whilst using topical facial steroids developed advanced glaucoma. A further two cases of ocular hypertension secondary to topical facial steroids are also described. This is the first series of cases to be reported demonstrating the potentially blinding complications of topical facial steroids. Recommendations are made with regard to screening such patients for glaucoma.