Welcome to issue 1 of 2012 and a belated Happy New Year to all CLAE readers and BCLA members. The hardest job I had for this issue was to decide which papers to include and which papers to hang on to and save for issue 2 of 2012. At the end of December when I was choosing the content for this issue there were additional 5 papers that could have been included. The final choice came down to various factors; such as first come first served – i.e. which papers had been ready and waiting the longest; secondly which papers had been submitted the earliest; are there similar papers so that it may be beneficial to publish them alongside this paper; and also was the content something which needed to be out there quicker than other papers as it was a current hot topic? But it should be noted that once papers are proofed and deemed ready by authors they are published in the epub version and put online for others to see in their final version. An epub version is given a DOI number (digital object identifier) so that it can be cited by other authors. Apart from being on line the only other difference is that an epub version is essentially waiting to be assigned to a particular issue. So those papers that are being held off for issue 2 of this year are actually already available for you to read (and cite) on line.

Abstract: Contact lens wear continues to be the highest single risk factor for microbial keratitis, particularly when worn in the extended wear modality. For microbial keratitis to occur, the presence of at least a bacterial load as well as a break in the corneal surface is required. One such break occurs in the case of a corneal erosion. These well-circumscribed areas of full thickness epithelial loss can occur both with and without contact lens wear, however the risk of infection is greater in the presence of a lens due to its capacity to provide a vector for the entry of bacterial pathogens. While erosions in non-contact lens wearers are thought to result from defective epithelial basement membrane anchoring, the underlying causes during contact lens wear are yet unknown. This article sets out to review corneal erosions associated with contact lens wear, their associated risk factors such as extended wear, the mechanisms that may be responsible for their formation and the factors that differentiate them from other contact lens related adverse events. Appropriate diagnosis and understanding of the relevant pathophysiology is important to the effective treatment and an understanding of the aetiological factors responsible for erosions is critical to the development of preventative strategies and effective clinical care.

Abstract: Allergic eye disease encompasses a group of hypersensitivity disorders which primarily affect the conjunctiva and its prevalence is increasing. It is estimated to affect 8% of patients attending optometric practice but is poorly managed and rarely involves ophthalmic assessment. Seasonal allergic conjunctivitis (SAC) is the most common form of allergic eye disease (90%), followed by perennial allergic conjunctivitis (PAC; 5%). Both are type 1 IgE mediated hypersensitivity reactions where mast cells play an important role in pathophysiology. The signs and symptoms are similar but SAC occurs periodically whereas PAC occurs year round. Despite being a relatively mild condition, the effects on the quality of life can be profound and therefore they demand attention. Primary management of SAC and PAC involves avoidance strategies depending on the responsible allergen(s) to prevent the hypersensitivity reaction. Cooled tear supplements and cold compresses may help bring relief. Pharmacological agents may become necessary as it is not possible to completely avoid the allergen(s). There are a wide range of anti-allergic medications available, such as mast cell stabilisers, antihistamines and dual-action agents. Severe cases refractory to conventional treatment require anti-inflammatories, immunomodulators or immunotherapy. Additional qualifications are required to gain access to these medications, but entry-level optometrists must offer advice and supportive therapy. Based on current evidence, the efficacy of anti-allergic medications appears equivocal so prescribing should relate to patient preference, dosing and cost. More studies with standardised methodologies are necessary elicit the most effective anti-allergic medications but those with dual-actions are likely to be first line agents.

Abstract: Purpose: To evaluate the influence of cone location and corneal cylinder on RGP corrected visual acuities and residual astigmatism in patients with keratoconus.Methods: In this prospective study, 156 eyes from 134 patients were enrolled. Complete ophthalmologic examination including manifest refraction, Best spectacle visual acuity (BSCVA), slit-lamp biomicroscopy was performed and corneal topography analysis was done. According to the cone location on the topographic map, the patients were divided into central and paracentral cone groups. Trial RGP lenses were selected based on the flat Sim K readings and a ‘three-point touch’ fitting approach was used. Over contact lens refraction was performed, residual astigmatism (RA) was measured and best-corrected RGP visual acuities (RGPVA) were recorded.Results: The mean age (±SD) was 22.1±5.3 years. 76 eyes (48.6%) had central and 80 eyes (51.4%) had paracentral cone. Prior to RGP lenses fitting mean (±SD) subjective refraction spherical equivalent (SRSE), subjective refraction astigmatism (SRAST) and BSCVA (logMAR) were −5.04±2.27D, −3.51±1.68D and 0.34±0.14, respectively. There were statistically significant differences between central and paracentral cone groups in mean values of SRSE, SRAST, flat meridian (Sim K1), steep meridian (Sim K2), mean K and corneal cylinder (p-values

Abstract: Purpose: The aim of this study was to obtain intraocular forward light scatter (FLS) data in keratoconus patients and to explore possible relationships with contrast sensitivity.Method: Intraocular straylight was assessed in the right eye of 10 visually-normal subjects (31±5 years) and 5 keratoconus patients (34±9 years) using the van den Berg straylight meter. Contrast sensitivity was also measured in both groups, with and without a glare source provided by the Brightness Acuity Tester (BAT), using a Pelli–Robson chart. Inclusion criteria for the keratoconic patients were chosen to avoid natural causes of increased scatter and to limit the influence of factors that could affect the straylight measurements.Results: Intraocular light scatter was significantly greater in the keratoconic patients than in normal subjects for each of the three eccentricities tested (Mann–Whitney U test (2-tailed): Z≤−2.2, p≤0.027). Baseline Pelli–Robson contrast sensitivity was also found to be lower in the keratoconus group than in the normal subjects (Mann–Whitney U test: Z=−2.2, p=0.023). Under glare conditions contrast loss was significantly greater in the keratoconic patients than in the normal subjects (Mann–Whitney U test: Z=−2.5, p=0.013). High levels of negative correlation were found between the magnitudes of intraocular straylight and baseline contrast sensitivity in the keratoconus group (Spearman's correlation coefficient (RS)≤−0.87, p≤0.027).Conclusion: The high values of straylight measured in the keratoconic patients cannot be explained by age or scarring and could be related to the structural degradation of the cornea. Further investigation of intraocular scatter in keratoconus is warranted to improve our current understanding of the visual deficits associated with this pathology.

Abstract: Purpose: To develop a theoretical ‘cost-per-wear’ model of contact lens wear, as tool for UK practitioners to assist patients in determining the most cost-effective lens replacement and wearing frequency protocols.Methods: The annual cost of professional fees, contact lenses and solutions when wearing daily, two weekly and monthly replacement contact lenses was determined for spherical, toric and multifocal prescription types. This annual cost was divided by the number times lenses are worn per year, resulting in a cost-per-wear.Results: The cost-per-wear for two weekly and monthly replacement contact lenses is similar, both decreasing with increasing frequency of wear. The cost-per-wear of daily replacement lenses is lower than for reusable lenses when worn 1–2 days per week (DPW), but higher when worn 4–7 DPW. The ‘cross-over point’ for spherical lenses at which the cost-per-wear is virtually the same for the three replacement frequencies, approximately £2.06, occurs at 3 DPW. The cross-over point for toric lenses is at 4 DPW with daily compared to two weekly replacement lenses (£2.06) and between 2–3 DPW with daily compared to monthly replacement contact lenses (£2.39). The crossover point for multifocal lenses of all replacement frequencies is between 4 and 5 DPW (£1.79).Conclusions: In general, daily replacement contact lenses are more cost-effective when worn on a part-time basis (1–3 DPW) and reusable lenses are more cost-effective when worn full-time (4–7 DPW). This cost-per-wear model will assist practitioners in making an informed decision when offering advice to patients relating to the most suitable replacement modality.

Abstract: Purpose: To (i) analyze the repeatability of fluorescein instillation from a modified fluorescein strip (MFS) compared to a standard fluorescein strip (FS), and to (ii) observe its usefulness in the measurement of the fluorescein break-up time (FBUT) in comparison to the Tearscope (NIBUT).Methods: In-vitro: Intra- and inter-observer repeatability in fluorescein instillation from the MFS and FS was evaluated by fluorescence analysis (n=10, each). In-vivo: BUT of the right eye of 20 randomly selected subjects (mean age 43.3±11.5, range=21–60 years, 8 males, 12 females) was measured by use of the Tearscope and MFS. Subjects were grouped by the Ocular Surface Disease Index (OSDI) score into 8 OSDI+ and 12 OSDI− by a cut-off value of 15.Results: In-vitro: Intra-observer 95% limit of agreement (LoA) of the MFS was similar to the FS LoA in observer 1 (O1), but better than the FS LoA in observer (O2) (MFS: O1: LoA=±1.98mW; p=0.179; O2: ±2.71; 0.442; FS: O1: ±1.71; 0.246; O2: ±4.11; 0.512). Inter-observer LoA in fluorescence was better in MFS (±1.42; 0.111) than in FS (±3.71; 0.003). In-vivo: MFS-BUT was significantly shorter than the NIBUT (p=0.002), but significantly correlated (r=0.864, p

Abstract: Purpose: To study the thickness profile of the normal cornea in order to establish any correlation between central and peripheral points.Methods: Sixty-seven eyes of 40 patients were subjected to central corneal thickness measurement (CCT) with an ultrasound pachymeter (UP) and corneal thickness mapping with the Oculus Pentacam. The corneal apex thickness (CAT), pupil centre thickness (recorded as CCT and corresponded to CCT of UP) and thickness at the thinnest location (CTL) were obtained and compared with each other. Corneal thickness data at 3mm and 7mm temporally, nasally, superiorly and inferiorly from the corneal apex were obtained. The mean corneal thickness values along the 2, 4, 6, 8 and 10mm diameter concentric circles, with the CTL as the centre, were also obtained. The above data at different points were statistically correlated.Results: There was no significant difference between CCT readings measured by UP and Pentacam (P=0.721). There was high positive correlation between the CAT values and the thickness at 3mm (R≥0.845, P

Abstract: Penetrating injuries from non-venomous snakebites are, thankfully, rare. They are, however, sight-threatening and the recent trend for using non-venomous snakes as props in the entertainment industry is increasing exposure of this hazard to people with no animal handling training. We report a case of a penetrating corneal injury in a 35 year old woman following a bite from a snake she had been given to hold for a photograph opportunity. The injury was repaired surgically and she had a good visual outcome, largely due to very good fortune in the site and nature of the injury. This case highlights the danger of exposing untrained handlers to snakes in the entertainment industry.