Ian Murdoch

Beta irradiation: new uses for an old treatment: a review

AbstractBeta radiation has a long history as a treatment modality in ophthalmology. It is a convenient and practical method of applying radiation and has the advantage of minimal tissue penetration. There has been a recent resurgence in the use of beta radiation in other areas in medicine, such as the prevention of restenosis after coronary artery stenting. Beta radiation has been shown in vitro and in vivo to inhibit proliferation of human Tenons fibroblasts, which enter a period of growth arrest but do not die. Effects on the cell cycle controller p53 have been shown to be important in this process.In ophthalmology, beta radiation has been used widely for the treatment of pterygium and is under evaluation for treatment of age-related macular degeneration and for controlling wound healing after glaucoma drainage surgery. In this latter role, beta radiation may be particularly appropriate for use in developing countries to improve the results of trabeculectomy while potentially avoiding some of the side effects of other antimetabolites.

Evaluating a new logMAR chart designed to improve visual acuity assessment in population-based surveys

AbstractAims This study aimed to evaluate a new chart designed to improve the collection of visual acuity data in population-based surveys. The Reduced logMAR E chart (RLME) employs three letters per line, ‘tumbling E’ optotypes, and conforms to accepted contemporary design principles.Methods The performance of the chart was assessed within a population-based glaucoma survey in Thailand. Performance indices were test–retest variability (TRV) and agreement with acuity data measured using the ETDRS logMAR chart which acted as the ‘gold standard’.ResultsThe 95% confidence limits for TRV of RLME acuity data were ±0.15 logMAR. This figure is consistent with published data on the TRV of acuities measured using five-letter-per-line logMAR charts. The mean difference between RLME and ETDRS acuity data was 0.00 logMAR (95% confidence intervals of ±0.05 logMAR) indicating that RLME acuities agreed well with those of the ETDRS chart. The chart and its method of use was readily accepted by the local ancillary staff who required only minimal training before acuity measurement could be delegated to them.Conclusions The study demonstrated that the RLME chart is capable of accurate and repeatable acuity measurements. Certain aspects of the design of the RLME chart may be particularly pertinent to the measurement of vision in population-based surveys.

Distribution and aetiology of blindness and visual impairment in mesoendemic onchocercal communities, Kaduna State, Nigeria. Kaduna Collaboration for Research on Onchocerciasis.

During a field trial of ivermectin in Kaduna State, 6831 people age 5 years and above, living in 34 mesoendemic onchocercal communities in Kaduna State, northern Nigeria, were examined for ocular disease. Visual function assessments included tests of visual acuity and visual fields. A total of 185 individuals (2.7%) were bilaterally blind by acuity criteria with a further 28 blind by field constriction. The overall prevalence of blindness was 3.1%. A further 118 individuals were visually impaired by WHO criteria. Examination for the cause of blindness revealed that 43% of eyes in bilaterally blind patients were blind due to onchocerciasis. A further 11% were blind from optic atrophy much of which was probably onchocercal in origin. Glaucoma was the next most common cause of blindness in the bilaterally blind (11%). Only 6% of eyes were blind from cataract as the primary cause. In the visually impaired population cataract was the most common primary cause of impaired/blind eyes (31%), followed by onchocerciasis (19%) [corrected].

A national survey of diagnostic tests reported by UK community optometrists for the detection of chronic open angle glaucoma

Citation information: Myint J, Edgar DF, Kotecha A, Murdoch IE & Lawrenson JG. A national survey of diagnostic tests reported by UK community optometrists for the detection of chronic open angle glaucoma. Ophthalmic Physiol Opt 2011, 31, 353–359. doi: 10.1111/j.1475‐1313.2011.00844.x

Changing trends in the incidence of bleb-related infection in trabeculectomy

Aim To investigate the incidence of late onset bleb-related infection (BRI) following Mitomycin C (MMC) augmented trabeculectomy procedures at a single institution. Methods This was a retrospective case series analysis of late onset BRI, defined as either blebitis or endophthalmitis occurring at least 1 month following a glaucoma filtration procedure. Data collected from hospital charts included the position of the conjunctival flap base. Two cohorts were examined: the first a sample of 194 intraoperative MMC augmented trabeculectomies undertaken over a 4-year period from 1993 to 1997, and the second a sample of 764 MMC trabeculectomies performed in a 4-year period between the years 1999 and 2005. Results A total of 11 cases of BRI (cumulative incidence 5.7%) were identified in the cohort from 1993 to 1997. BRI cases had trabeculectomies performed with a limbus-based conjunctival flap and presented at a median IQR 14.8 (9.4–42.9) months after surgery. In the 1999–2005 cohort, nine cases of BRI were identified (cumulative incidence 1.2%). All these BRI cases had a fornix-based conjunctival flap and presented at a median IQR 19.2 (6.1–44.1) months after trabeculectomy surgery. Conclusion This study found that the incidence of BRI was higher in MMC augmented trabeculectomy shortly after the introduction of MMC, but subsequently reduced to a lower level. While many changes in surgical technique had occurred in the intervening period, the most significant change was from limbus-based to fornix-based conjunctival flap. However, the retrospective nature of the study prevents the authors from concluding that there is a causative relationship between changes in surgical technique and BRI.

NICE – impact on glaucoma case detection

Citation information: Shah S & Murdoch IE. NICE – impact on glaucoma case detection. Ophthalmic Physiol Opt 2011, 31, 339–342. doi: 10.1111/j.1475‐1313.2011.00843.x

Barriers perceived by UK‐based community optometrists to the detection of primary open angle glaucoma

Purpose:  This paper aims to identify the barriers to case‐finding for primary open angle glaucoma (POAG) as perceived by community optometrists in the United Kingdom (UK).

The silent enemy: a review of cataract in relation to glaucoma and trabeculectomy surgery

Glaucoma is one of the leading causes of blindness worldwide. In the UK, the estimated prevalence of open angle glaucoma ranges from 0.3% in the 40s to 3.3% in the 70s. It is one of the leading causes for blind registration in the UK, second only to macular degeneration. Trabeculectomy remains the mainstay of surgical treatment. In this review, the authors look at the evidence and reasons for cataract formation after trabeculectomy surgery and examine the evidence surrounding bleb failure after cataract extraction. The review highlights that the reasons for cataract formation in those undergoing filtration surgery are poorly understood, and more research needs to be undertaken in this area.

Glaucoma case finding: a cluster-randomised intervention trial

AbstractPurpose To assess the effect of an intervention comprising training in optic disc assessment, explicit referral criteria and ophthalmologist feedback on referred patients, on the number of optometrist referrals for suspected glaucoma seen at a referral site and the positive predictive value of those referrals.Methods Optometric practices routinely referring to the Ealing Hospital Eye Clinic were randomly divided into two groups taking into consideration those practices, which shared an optometrist (a cluster) and the number of optometrist days worked per week. One group of practices acted as controls, while the other practices were invited to receive the intervention. Data on 397 new patients referred and presenting to Ealing Hospital with suspected glaucoma were collected over a 20-month period. The data on patients who had failed to attend their appointment were collected over 7 months of this period. The number of referrals seen, the positive predictive value of those referrals, and the attendance rate were calculated. Optometrists opinions of the intervention were assessed qualitatively. Data relating to optometrist compliance with the intervention were also collected.Results The number of glaucoma referrals presenting to Ealing Hospital from the intervention practices was almost double that from the control practices (210 vs 119). When cluster randomisation, the number of optometrist days per cluster and the number of assessed referrals in the preintervention period are taken into consideration, it is estimated that the intervention is associated with a 52% increase in the number of referrals reaching Ealing Hospital. However, the design effect resulting from the cluster randomisation was unexpectedly high (of the order of 13–14) and so the confidence intervals around the estimate of 52% are very wide (95% c.i. 35% decrease to 253% increase, P=0.34). There was no evidence of an association between optometrist compliance with the intervention and the number of referrals seen at Ealing Hospital. The positive predictive value (PPV) of referrals was similar for the intervention (0.49 (95% c.i. 0.42, 0.55)) and control groups (0.46 (95% c.i. 0.33, 0.60)). Optometrist opinions of the intervention were largely favourable. All expressed a willingness to participate in future programmes.Conclusion A large difference in the number of referrals between the practice groups was observed. Since the PPV of referral was unchanged, the potential impact of the intervention in terms of numbers of new cases of glaucoma detected in the community is substantial. However, because of its large design effect, this trial does not provide conclusive evidence of an impact of the intervention on referral numbers. A considerably larger trial will be required to produce conclusive evidence of an effect.

Postoperative evaluation of patients following ophthalmic surgery.

We have used telemedicine to support the postoperative evaluation of patients who have had ophthalmic surgery. Mobile telemedicine workstations connected using three ISDN lines have enabled us to review patients at an outreach clinic on the first postoperative day. Video slit-lamp images of the patient are captured by a trained ophthalmic nurse at the outreach clinic and viewed by surgeons at Moorfields Eye Hospital in central London during live teleconsultations. During the study period, over 80 teleconsultations were carried out on postoperative cataract, trabeculectomy and combined procedures. Preliminary results are very encouraging. Although 8 (33%) of 24 patients were anxious about being involved in the teleconsultation, 20 (83%) had confidence in the system and only one (4%) found the experience unacceptable.