Defining response to anti-VEGF therapies in neovascular AMD.

The introduction of anti-vascular endothelial growth factor (anti-VEGF) has made significant impact on the reduction of the visual loss due to neovascular age-related macular degeneration (n-AMD). There are significant inter-individual differences in response to an anti-VEGF agent, made more complex by the availability of multiple anti-VEGF agents with different molecular configurations. The response to anti-VEGF therapy have been found to be dependent on a variety of factors including patient's age, lesion characteristics, lesion duration, baseline visual acuity (VA) and the presence of particular genotype risk alleles. Furthermore, a proportion of eyes with n-AMD show a decline in acuity or morphology, despite therapy or require very frequent re-treatment. There is currently no consensus as to how to classify optimal response, or lack of it, with these therapies. There is, in particular, confusion over terms such as 'responder status' after treatment for n-AMD, 'tachyphylaxis' and 'recalcitrant' n-AMD. This document aims to provide a consensus on definition/categorisation of the response of n-AMD to anti-VEGF therapies and on the time points at which response to treatment should be determined. Primary response is best determined at 1 month following the last initiation dose, while maintained treatment (secondary) response is determined any time after the 4th visit. In a particular eye, secondary responses do not mirror and cannot be predicted from that in the primary phase. Morphological and functional responses to anti-VEGF treatments, do not necessarily correlate, and may be dissociated in an individual eye. Furthermore, there is a ceiling effect that can negate the currently used functional metrics such as >5 letters improvement when the baseline VA is good (ETDRS>70 letters). It is therefore important to use a combination of both the parameters in determining the response.The following are proposed definitions: optimal (good) response is defined as when there is resolution of fluid (intraretinal fluid; IRF, subretinal fluid; SRF and retinal thickening), and/or improvement of >5 letters, subject to the ceiling effect of good starting VA. Poor response is defined as <25% reduction from the baseline in the central retinal thickness (CRT), with persistent or new IRF, SRF or minimal or change in VA (that is, change in VA of 0+4 letters). Non-response is defined as an increase in fluid (IRF, SRF and CRT), or increasing haemorrhage compared with the baseline and/or loss of >5 letters compared with the baseline or best corrected vision subsequently. Poor or non-response to anti-VEGF may be due to clinical factors including suboptimal dosing than that required by a particular patient, increased dosing intervals, treatment initiation when disease is already at an advanced or chronic stage), cellular mechanisms, lesion type, genetic variation and potential tachyphylaxis); non-clinical factors including poor access to clinics or delayed appointments may also result in poor treatment outcomes. In eyes classified as good responders, treatment should be continued with the same agent when disease activity is present or reactivation occurs following temporary dose holding. In eyes that show partial response, treatment may be continued, although re-evaluation with further imaging may be required to exclude confounding factors. Where there is persistent, unchanging accumulated fluid following three consecutive injections at monthly intervals, treatment may be withheld temporarily, but recommenced with the same or alternative anti-VEGF if the fluid subsequently increases (lesion considered active). Poor or non-response to anti-VEGF treatments requires re-evaluation of diagnosis and if necessary switch to alternative therapies including other anti-VEGF agents and/or with photodynamic therapy (PDT). Idiopathic polypoidal choroidopathy may require treatment with PDT monotherapy or combination with anti-VEGF. A committee comprised of retinal specialists with experience of managing patients with n-AMD similar to that which developed the Royal College of Ophthalmologists Guidelines to Ranibizumab was assembled. Individual aspects of the guidelines were proposed by the committee lead (WMA) based on relevant reference to published evidence base following a search of Medline and circulated to all committee members for discussion before approval or modification. Each draft was modified according to feedback from committee members until unanimous approval was obtained in the final draft. A system for categorising the range of responsiveness of n-AMD lesions to anti-VEGF therapy is proposed. The proposal is based primarily on morphological criteria but functional criteria have been included. Recommendations have been made on when to consider discontinuation of therapy either because of success or futility. These guidelines should help clinical decision-making and may prevent over and/or undertreatment with anti-VEGF therapy.

Bilateral thalamic lesions.

OBJECTIVE: Bilateral thalamic lesions are rare and relatively obscure neoplasms. We present our experience with nine cases of bilateral thalamic lesions and attempt to analyse them in the background of available literature. MATERIALS AND METHODS: Retrospective analyses of the case records of 9 cases of bilateral thalamic lesions treated in our department since January 2002, which have a minimum of 1 year follow-up. RESULTS: The study group included four males and five females with a mean age of 14.6 years (5 years to 29 years). Seven of these patients had radiological evidence of bilateral thalamic lesions at presentation and 2 patients had involvement of the opposite thalamus at a later stage of the disease. All patients except one presented with raised intracranial pressure symptoms. Focal motor deficits (4/9), behavioral and memory disturbances (3/9) were the other major presenting symptoms. Biopsy confirmation was possible in six patients and histopathology was suggestive of low grade fibrillary astrocytoma in all six patients. Seven patients required CSF diversion procedure for associated hydrocephalus. Eight of our nine patients underwent radiotherapy. On last follow-up, 3 patients were clinically stable with images suggestive of arrested disease, four patients had evidence of progressive disease both clinically and radiologically and there were two recorded cases of mortality. CONCLUSION: Primary bilateral thalamic lesions have characteristic neuroradiological properties and are distinct from unilateral thalamic tumours with bilateral progression. Almost all of these lesions on histology prove to be gliomas but decompressive surgery is seldom feasible. Surgical intervention is limited to biopsy and CSF diversion for hydrocephalus. Bilateral thalamic lesions remain unresponsive to adjuvant therapy and generally carry a poor prognosis.

Barrier functions of human skin: a holistic view.

The fascinating topic of skin barrier continues to engage researchers from diverse disciplines both in academia and industry. Much of the information on the basic biology of barrier formation, its ontogeny as well as repair and homeostasis comes from studies on animal models. A smaller number of human studies have validated the usefulness of animal models, while highlighting some essential differences. We submit that the human skin barrier is unique in several ways, as much due to our adaptive ability as our control over the environment (macro and micro) that none of the other species have exerted. The human skin is not only exposed to the greatest variations of environment due to our phenomenal mobility but also to the largest number of xenobiotics, both chemical and microbial, resulting from human activity. In this overview, we attempt to evaluate the interdependent relation of skin barriers to environmental stressors hoping to raise interest in some of the lesser known or neglected aspects of human skin barriers as they relate to skin health and dysfunctions.

New paradigms in the treatment of wet AMD: the impact of anti-VEGF therapy.

The incidence of age-related macular degeneration (AMD) in the United Kingdom is increasing with the ageing population. The wet form of this progressive and potentially blinding disease can develop very rapidly and lead to severe loss of central vision and reduction in quality of life, sometimes in just a matter of weeks. Recent advances in the treatment of wet AMD with the licensing of anti-vascular endothelial growth factor therapies, coupled with current guidance from the Scottish Medicines Consortium and the National Institute of Health and Clinical Excellence have led to a subsequent increase in workload at AMD clinics due to the increased number of patients now eligible for treatment. In addition, the Royal College of Ophthalmologists recommend a 2-week diagnosis to treatment schedule due to the aggressive nature of the disease. The role of the retinal specialist is thus changing, and business management skills are becoming increasingly necessary to obtain the necessary resources to implement the guidance. Through prior experience and formal external evaluation of services at Frimley Park and Harrogate District Hospitals, a number of critical success factors have been developed for optimising treatment pathways in efficient wet AMD clinics.

Tear lipid layer thickness and ocular comfort with a novel device in dry eye patients with and without Sjögren's syndrome.

BACKGROUND: To measure changes in tear-film lipid-layer thickness (LLT) and symptoms in patients with dry eye symptoms with and without Sjögren's syndrome after using a novel device. The device is designed to promote release of meibomian sebum into the tear film by delivering latent heat to the eyelids. STUDY DESIGN: Two prospective, controlled, randomised, observer-masked, single-intervention studies. METHODS: Two independent studies were conducted in a major university hospital in the South West of England. The first study involved 24 patients with dry eye symptoms without Sjögren's [the PDE study] and the second study involved 31 patients with dry eye symptoms and Sjögren's syndrome (the SS study). The PDE study was randomised into two groups. Group I (12 patients) underwent 10 min of treatment with the activated device and Group II (12 patients) had no treatment. The SS study was similarly randomised into Group I (17 patients) and Group II (14 patients). The LLT and subjective alterations in ocular comfort of each subject were assessed prior and immediately after 5 and 30 min subsequent to the 10-min period. In the SS study, a further assessment was carried out at 60 min. RESULTS: In the PDE study, treated patients exhibited a bilateral increase of LLT at 5 min (right eyes, 1.2 levels, p<0.0005; left eyes, 1.0 levels, p<0.0005, Mann-Whitney) and at 30 min (right eyes, 0.7 levels, p<0.005; left eyes, 0.6 levels, p<0.005). Mean symptom scores improved in the treated group compared with the control group at 5 min (treatment group, +2.0; control group, +0.2; p<0.05) and 30 min (treatment group, +2.8; control group, +0.4; p<0.015). In the SS study, treated patients exhibited a bilateral increase of LLT, 5 min (right eyes, 0.5 levels, p<0.009; left eyes, 0.5 levels, p<0.005, Monte Carlo 2-tailed), 30 min (right eyes, 0.5 levels, p<0.007; left eyes 0.5 levels, p<0.002) and 60 min (right eyes, 0.3 levels, p<0.1; left eyes, 0.3 levels, p<0.05). There was no change in any of the control patients in any of the assessments. With regard to symptom scores, the mean change at 5 min measured +0.8 in the treatment group and remained relatively unchanged at +0.1 in the control group (p<0.1). At 30 min, this change measured +1.3 in the treatment group and +0.1 in the control group (p<0.03) and at 60 min, the change measured +1.5 in the treatment group and remained at +0.1 in the control group (p<0.02). CONCLUSION: Meibomian therapy with this novel device increases LLT and ocular comfort in patients with dry eye symptoms with and without Sjögren's syndrome.

Tear film lipid layer thickness and ocular comfort after meibomian therapy via latent heat with a novel device in normal subjects.

AIM: This study measures changes in tear film lipid layer thickness (LLT) and ocular comfort in normal subjects after 10 min use of a novel device, which delivers meibomian therapy with latent heat. The device is designed to promote the release of meibomian sebum into the tear film by delivering latent heat to the eyelids, thus thickening the lipid layer. Normal lid movements are maintained, facilitating resurfacing of the tear film. METHOD: A prospective, controlled, observer masked, single intervention trial in which 24 normal subjects were randomised into three groups. Group I underwent 10 min treatment with the activated device, Group II used the inactivated device for the same duration of time, and Group III had no intervention. The LLT of each subject was measured with a Keeler Tearscope prior and subsequent to the 10-min period. Subjective alteration in ocular comfort was also assessed. RESULTS: Seven of eight subjects (87.5%) in Group I exhibited an increase in LLT. The mean LLT in this group showed a statistically significant increase (left eyes 1.0 levels, P<0.001, right eyes 0.9 levels, P<0.003) compared to Groups II and III. Six of eight subjects (75%) using the activated device experienced subjective improvement in ocular comfort. CONCLUSION: Meibomian therapy with this device increases LLT in normal individuals. This implies a more stable tear film, reflected in subjective improvement in ocular comfort.

Experimental determination of the anisotropy function and anisotropy factor for model 6711 I-125 seeds.

Model 6711 125I seeds are commonly used in permanent brachytherapy implants. While recommended dose distribution parameters for these sources have been published by AAPM TG-43, several investigators have recently questioned the presence of seemingly unphysical fluctuations in the anisotropy function data. Seeking to understand these, we measured the dimensions of eight model 6711 seeds radiographically, and made a new experimental determination of the anisotropy function and factor using thermoluminescent dosimeters (TL-100 chips and minicubes) in a solid water phantom. It was found that variations in seed capsule end weld thickness, and movement within the capsule of the Ag rod onto which the 125I is adsorbed, were present for all sources and thus contributed to experimental uncertainty. Averaging results from two different sources, from data acquired at the same time from diametrically opposed quadrants of the phantom, and from repeated measurements yielded anisotropy function values similar to those of TG-43 but characterized by greater precision (< or = 3% for radial distance r < or = 3 cm and < or = 1% for r > or = 4 cm), an absence of sharp fluctuations, and reduced magnitudes at r = 1 cm. The measured values can be well represented by an analytic function similar to that proposed by Furhang and Anderson to fit the TG-43 data. Values of the anisotropy factor derived from this function by integration exhibit little variation with r, in agreement with earlier diode data but in contrast to TG-43 data, and can also be represented by an analytic function. Finally, a difference in TLD chip and minicube reproducibility, observed here and by earlier investigators, is explained by reference to recent work (done concurrently with ours) as stemming from variations in dosimeter orientation and automated reader positioning/heating for minicubes.

The effect of vitamin D status on cutaneous sterologenesis in vivo and in vitro.

Recent studies have shown that cutaneous sterologenesis is autonomous from the influence of circulating sterols, and that the epidermis is an important site of sterologenesis which is regulated by permeability barrier requirements. In addition to barrier function, an additional, important function of the epidermis is to synthesize sterol precursors of vitamin D3. The present study was designed, first, to determine whether vitamin D status and/or circulating levels of 1,25-dihydroxyvitamin D3 might play a role in regulating cutaneous sterol synthesis in vivo and, second, whether 1,25-dihydroxyvitamin D3 modulates sterologenesis in cultured human keratinocytes. Hairless mice were maintained on a vitamin D-deficient diet in the dark and supplemented with various doses of vitamin D3/day. Despite demonstrating serum 25-hydroxyvitamin D3 levels ranging from less than 10 to 343 ng/ml, the incorporation of tritiated water into cholesterol and total nonsaponifiable lipids in both the epidermis and dermis was similar in the four groups of animals. Likewise, administration of various doses of 1,25-dihydroxyvitamin D3 to vitamin D-deficient mice resulted in serum levels of 1,25-dihydroxyvitamin D3 ranging from less than 10 to 85 pg/ml; yet, cholesterol and total nonsaponifiable lipid synthesis was similar in both the dermis and epidermis in all groups of animals. Moreover, administration of 0.6 micrograms/kg per day of 1,25-dihydroxyvitamin D3 to 'normal' vitamin D-replete mice also had no effect on cutaneous sterol synthesis. Furthermore, conversion of 7-dehydrocholesterol to cholesterol in vitamin D-deficient vs. supplemented animals did not differ. Finally, addition of 1,25-dihydroxyvitamin D3 to cultured keratinocytes over a concentration range of 10(-12)-10(-7) M did not affect sterologenesis, except at supraphysiologic doses (10(-7) M). Together, these results suggest that vitamin D status does not influence sterol synthesis in the skin.