PACS plus criteria: a retrospective cohort review of 612 consecutive patients treated with bilateral YAG peripheral iridotomies.

INTRODUCTION: With an ageing population and better life expectancy, the prevalence of angle closure disease is expected to increase by 20% per decade. In 2022, the Royal College of Ophthalmologists (RCOphth) issued a guideline on managing angle closure disease. Hospital eye service (HES) referral and prophylactic treatment are recommended only for primary angle closure suspect (PACS) with "Plus" features only. We aimed to examine patients previously treated with YAG peripheral iridotomies (YAG PI) for the presence of "PACS Plus" features. METHODS: A retrospective cohort study of consecutive patients treated with YAG PI between 2015 and 2019 at a tertiary referral NHS eye centre was reviewed. Cases were examined to identify and classify patients into Primary Angle Closure (PAC), PACS, and Primary Angle Closure Glaucoma (PACG). Patients with PACS were studied for "Plus" features. RESULTS: Six hundred twelve patients with gonioscopy-confirmed angle closure (defined as a minimum 180 degrees iridotrabecular contact) treated with YAG PI from years 2015 to 2019 were included in the analysis. The mean age of patients presenting with angle closure disease was 68.5 years (SD 11.3). There were 390 (63.7%) patients with PACS, 102 (16.6%) with PAC and 120 (19.7%) with PACG. Of the PACS patients, 159(40.8%) patients had no "Plus" features. 181 (40.2%) patients had 1 "Plus" feature, 37 (9.5%) had 2 "Plus" features and 13 (3.3%) patients had 3 "Plus" features. CONCLUSION: In our cohort, a considerable proportion (40.8%) of PACS patients treated with YAG PI did not have Plus features and therefore that would not meet the proposed criteria for HES referral and YAG PI. With the proposed guidance, we expect a considerable reduction in HES referrals. Nonetheless, community optometry services should be supported and trained to provide monitoring for patients with PACS not referred to the HES.

Minimising prescription errors-a quality improvement project in the ophthalmology department in a tertiary referral hospital.

PURPOSE: The aim of this quality improvement project was to look into the hospital prescriptions and to identify and record the type and number of errors, to implement measures to reduce the risk of these errors and then to reaudit to assess the impact of changes implemented. METHODS: The initial audit was conducted prospectively over a eleven-week period. Prescriptions written by doctors of all grades and members of the staff, such as optometrists and nurses, were analysed. A glaucoma prescription guide along with more training at prescribing for doctors was introduced with a view to reducing these errors. A reaudit later demonstrated a significant reduction in these errors. RESULTS: After the introduction of a glaucoma prescription guide and more training for all grades of staff members, prescription errors reduced to 73/2342 (3.1%). Reaudit showed a reduction in both prescription writing errors 50/73(68.4%) and drug-related errors 23/73(31.6%). CONCLUSION: Prescription errors are avoidable. This audit demonstrated that providing an accessible, easy to read and understand glaucoma prescription guide in the outpatient department along with targeted training for medical staff in prescribing can help in minimising these errors and can lead to safer practice.

Comparison of Saccadic Vector Optokinetic Perimetry and Standard Automated Perimetry in Glaucoma. Part I: Threshold Values and Repeatability.

PURPOSE: We evaluated threshold saccadic vector optokinetic perimetry (SVOP) and compared results to standard automated perimetry (SAP). METHODS: A cross-sectional study was done including 162 subjects (103 with glaucoma and 59 healthy subjects) recruited at a university hospital. All subjects underwent SAP and threshold SVOP. SVOP uses an eye tracker to monitor eye movement responses to stimuli and determines if stimuli have been perceived based on the vector of the gaze response. The test pattern used was equivalent to SAP 24-2 and stimuli were presented at Goldmann III. Average and pointwise sensitivity values obtained from both tests were compared using Pearson's correlation coefficient. Two versions of SVOP were evaluated. RESULTS: A total of 124 tests were performed with SAP and SVOP version 2. There was excellent agreement between mean threshold values obtained using SVOP and SAP (r = 0.95, P < 0.001). Excluding the blind spot, correlation between SVOP and SAP individual test point sensitivity ranged from 0.61 to 0.90, with 48 of 54 (89%) test points > 0.70. Overall SVOP showed good repeatability with a Pearson correlation of 0.88. The repeatability on a point-by-point basis ranged from 0.66 to 0.98, with 45 of 54 points (83%) > 0.80. Repeatability of SAP was 0.87, ranging from 0.69 to 0.96, with 47 of 54 (87%) points > 0.80. CONCLUSION: Eye-tracking perimetry is repeatable and compares well with the current gold standard of SAP. The technique has advantages over conventional perimetry and could be useful for evaluating glaucomatous visual field loss, particularly in patients who may struggle with conventional perimetry. TRANSLATIONAL RELEVANCE: Suprathreshold SVOP already is in the field. To our knowledge, this is the first report of threshold SVOP and provides a benchmark for future iterations.

Comparison of Threshold Saccadic Vector Optokinetic Perimetry (SVOP) and Standard Automated Perimetry (SAP) in Glaucoma. Part II: Patterns of Visual Field Loss and Acceptability.

PURPOSE: We compared patterns of visual field loss detected by standard automated perimetry (SAP) to saccadic vector optokinetic perimetry (SVOP) and examined patient perceptions of each test. METHODS: A cross-sectional study was done of 58 healthy subjects and 103 with glaucoma who were tested using SAP and two versions of SVOP (v1 and v2). Visual fields from both devices were categorized by masked graders as: 0, normal; 1, paracentral defect; 2, nasal step; 3, arcuate defect; 4, altitudinal; 5, biarcuate; and 6, end-stage field loss. SVOP and SAP classifications were cross-tabulated. Subjects completed a questionnaire on their opinions of each test. RESULTS: We analyzed 142 (v1) and 111 (v2) SVOP and SAP test pairs. SVOP v2 had a sensitivity of 97.7% and specificity of 77.9% for identifying normal versus abnormal visual fields. SAP and SVOP v2 classifications showed complete agreement in 54% of glaucoma patients, with a further 23% disagreeing by one category. On repeat testing, 86% of SVOP v2 classifications agreed with the previous test, compared to 91% of SAP classifications; 71% of subjects preferred SVOP compared to 20% who preferred SAP. CONCLUSIONS: Eye-tracking perimetry can be used to obtain threshold visual field sensitivity values in patients with glaucoma and produce maps of visual field defects, with patterns exhibiting close agreement to SAP. Patients preferred eye-tracking perimetry compared to SAP. TRANSLATIONAL RELEVANCE: This first report of threshold eye tracking perimetry shows good agreement with conventional automated perimetry and provides a benchmark for future iterations.

The Effect of Socio-Economic Status on Severity of Periocular Basal Cell Carcinoma at Presentation.

PURPOSE: To evaluate the influence of socio-economic factors on size of periocular basal cell carcinoma at presentation. METHODS: All periocular basal cell carcinoma cases receiving treatment from the oculoplastics team in South Glasgow Hospitals NHS Trust, Glasgow, between 1999 and 2009, were identified retrospectively. Information collected included demographic details of patients, side and site of lesions, type of lesions, and size of lesions. The size of lesion was defined as small for any dimension not exceeding 5 mm, medium for dimensions between 6 mm and 10 mm, and large for dimensions exceeding 11 mm. Home address was used to determine the Scottish Index of Multiple Deprivation rank. The demographics, size of lesion, and Scottish Index of Multiple Deprivation rank were investigated using the general linear regression modelling. RESULTS: Of the 67 cases, 24 were men and 43 were women. The mean age was 71.5 years. There were a total of 67 identified cases, of which 38 presented with small-size lesions, 24 with medium-size lesions, and 5 with large-size lesions. Scottish Index of Multiple Deprivation is related to the presenting incidence of basal cell carcinoma, with the lower ranks presenting more frequently. CONCLUSIONS: Socio-economic deprivation is associated with larger and more frequent presentation of periocular basal cell carcinoma. This highlights the importance of raising awareness among populations of the more deprived areas of the significance of lumps and bumps within the periocular regions.

On Channel-Discontinuity-Constraint Routing in Wireless Networks.

Multi-channel wireless networks are increasingly deployed as infrastructure networks, e.g. in metro areas. Network nodes frequently employ directional antennas to improve spatial throughput. In such networks, between two nodes, it is of interest to compute a path with a channel assignment for the links such that the path and link bandwidths are the same. This is achieved when any two consecutive links are assigned different channels, termed as "Channel-Discontinuity-Constraint" (CDC). CDC-paths are also useful in TDMA systems, where, preferably, consecutive links are assigned different time-slots. In the first part of this paper, we develop a t-spanner for CDC-paths using spatial properties; a sub-network containing O(n/θ) links, for any θ > 0, such that CDC-paths increase in cost by at most a factor t = (1-2 sin (θ/2))-2. We propose a novel distributed algorithm to compute the spanner using an expected number of O(n log n) fixed-size messages. In the second part, we present a distributed algorithm to find minimum-cost CDC-paths between two nodes using O(n2) fixed-size messages, by developing an extension of Edmonds' algorithm for minimum-cost perfect matching. In a centralized implementation, our algorithm runs in O(n2) time improving the previous best algorithm which requires O(n3) running time. Moreover, this running time improves to O(n/θ) when used in conjunction with the spanner developed.

Off-axis digital flash photography: a common cause of artefact leukocoria in children.

Leukocoria, a presenting sign in several significant pediatric ocular conditions, can be artefactually produced by off-axis flash photography in healthy eyes. The authors demonstrate the conditions needed to produce this phenomenon, which is more commonly seen in children due to their larger-sized pupils, photogenicity, and frequent off-axis shots.

Intraosseous glomus tumor in acromion process of scapula.

A 25-year-old woman presented with a 5-year history of left shoulder pain, which was constant dull aching in nature, non-radiating with no relieving or aggravating factors and no seasonal variation, gradually increasing in intensity over years. There was no history of trauma or constitutional symptoms. the patient had taken anti-tubercular drugs for 6 months for this pain with no relief. There was point tenderness over the left acromion process. Local temperature was not raised. Movements of the left shoulder were not effected. All routine hematological investigations were normal. Surgical exploration of the lesion revealed a normal soft tissue periosteum and cortex. On removing the cortical bone a red colored jellified tissue was isolated and thoroughly curetted. Histopathology revealed intraosseous glomus tumor. The patient became pain free immediately postoperatively and continued to be symptom free at 24-month follow-up. Glomus tumor located within bone is rare. Only 22 cases of primary intraosseous glomus tumor have been reported in world literature. Glomus tumors are generally treated by meticulously shelling out the entire lesion. Recurrence of symptoms and the need for reoperation have been reported between 12% and 24%. Most authors assume the recurrence is due to inadequate excision, prompting some to recommend more extensive en bloc excision. Tuberculosis being endemic in this region, antituberculer chemotherapy is generally started on clinical suspicion and tissue diagnosis is only attempted in nonresponders. This case however re-emphasizes the value of tissue diagnosis especially when a lesion is at an unusual site like the acromion process.

Resolving the biodiversity paradox.

The paradox of biodiversity involves three elements, (i) mathematical models predict that species must differ in specific ways in order to coexist as stable ecological communities, (ii) such differences are difficult to identify, yet (iii) there is widespread evidence of stability in natural communities. Debate has centred on two views. The first explanation involves tradeoffs along a small number of axes, including 'colonization-competition', resource competition (light, water, nitrogen for plants, including the 'successional niche'), and life history (e.g. high-light growth vs. low-light survival and few large vs. many small seeds). The second view is neutrality, which assumes that species differences do not contribute to dynamics. Clark et al. (2004) presented a third explanation, that coexistence is inherently high dimensional, but still depends on species differences. We demonstrate that neither traditional low-dimensional tradeoffs nor neutrality can resolve the biodiversity paradox, in part by showing that they do not properly interpret stochasticity in statistical and in theoretical models. Unless sample sizes are small, traditional data modelling assures that species will appear different in a few dimensions, but those differences will rarely predict coexistence when parameter estimates are plugged into theoretical models. Contrary to standard interpretations, neutral models do not imply functional equivalence, but rather subsume species differences in stochastic terms. New hierarchical modelling techniques for inference reveal high-dimensional differences among species that can be quantified with random individual and temporal effects (RITES), i.e. process-level variation that results from many causes. We show that this variation is large, and that it stands in for species differences along unobserved dimensions that do contribute to diversity. High dimensional coexistence contrasts with the classical notions of tradeoffs along a few axes, which are often not found in data, and with 'neutral models', which mask, rather than eliminate, tradeoffs in stochastic terms. This mechanism can explain coexistence of species that would not occur with simple, low-dimensional tradeoff scenarios.

Leucocytoclastic vasculitis presenting as bilateral marginal keratitis.

Leucocytoclastic vasculitis is an immune-mediated, neutrophil-induced small vessel disease. Clinically, it presents with cutaneous palpable painless purpuric papules on the extremities. Ocular manifestation reported in the literature is rare and includes peripheral ulcerative keratitis, panuveitis and multifocal retinitis all preceded by cutaneous lesions. Herein a fatal case of leucocytoclastic vasculitis initially presenting with bilateral marginal keratitis without any cutaneous lesions is reported.

Fast molecular shape matching using contact maps.

In this paper, we study the problem of computing the similarity of two protein structures by measuring their contact-map overlap. Contact-map overlap abstracts the problem of computing the similarity of two polygonal chains as a graph-theoretic problem. In R3, we present the first polynomial time algorithm with any guarantee on the approximation ratio for the 3-dimensional problem. More precisely, we give an algorithm for the contact-map overlap problem with an approximation ratio of sigma where sigma = min{sigma(P1), sigma(P2)} 0, is hard.

Faster algorithms for optimal multiple sequence alignment based on pairwise comparisons.

Multiple Sequence Alignment (MSA) is one of the most fundamental problems in computational molecular biology. The running time of the best known scheme for finding an optimal alignment, based on dynamic programming, increases exponentially with the number of input sequences. Hence, many heuristics were suggested for the problem. We consider a version of the MSA problem where the goal is to find an optimal alignment in which matches are restricted to positions in predefined matching segments. We present several techniques for making the dynamic programming algorithm more efficient, while still finding an optimal solution under these restrictions. We prove that it suffices to find an optimal alignment of the predefined sequence segments, rather than single letters, thereby reducing the input size and thus improving the running time. We also identify "shortcuts" that expedite the dynamic programming scheme. Empirical study shows that, taken together, these observations lead to an improved running time over the basic dynamic programming algorithm by 4 to 12 orders of magnitude, while still obtaining an optimal solution. Under the additional assumption that matches between segments are transitive, we further improve the running time for finding the optimal solution by restricting the search space of the dynamic programming algorithm.