Visualizing ocular vasculature is important in clinical ophthalmology because ocular circulation abnormalities are early signs of ocular diseases. Photoacoustic microscopy (PAM) images the ocular vasculature without using exogenous contrast agents, avoiding associated side effects. Moreover, 3D PAM images can be useful in understanding vessel-related eye disease. However, the complex structure of the multi-layered vessels still present challenges in evaluating ocular vasculature. In this study, we demonstrate a new method to evaluate blood circulation in the eye by combining in vivo PAM imaging and an ocular surface estimation method based on a machine learning algorithm: a random sample consensus algorithm. By using the developed estimation method, we were able to visualize the PA ocular vascular image intuitively and demonstrate layer-by-layer analysis of injured ocular vasculature. We believe that our method can provide more accurate evaluations of the eye circulation in ophthalmic applications.

OBJECTIVE: New therapies are often introduced into the NHS prior to full evaluation, leading to inequities in provision. Uncertainty exists regarding the value of photodynamic therapy in the treatment of neovascular age-related macular degeneration. We ascertained the availability of this treatment and the information used to inform clinical policy.
METHODS: A postal survey of all clinical directors/lead consultants in the UK sought data on which (if any) patients were referred or treated with PDT by their unit, the sources of evidence informing clinical policy and the threshold of clinical benefit at which respondents would support the use of PDT.
RESULTS: 123/152 questionnaires were returned. 42% of units make some provision for PDT on the NHS, including routine provision by 9%. 14.5% of units offer the option of care in the private sector, whilst 26.5% treated or referred no patients. The threshold at which respondents considered introduction of PDT would be justifiable varied widely. Respondents cited local literature review, advice from clinicians, guidance from the Royal College and information from the pharmaceutical industry as most influential in determining current policy. However, the National Institute for Clinical Excellence (NICE) and the Cochrane Library were anticipated as playing a greater role in shaping future practice.
CONCLUSIONS: Substantial variation exists in the availability of PDT. Advocates of PDT may interpret our data as an indication of the NHS failing to provide an effective therapy equitably, whilst others may deduce that patients are receiving an under-evaluated treatment in routine clinical practice. The differing thresholds at which clinicians believe treatment would be justified may further exacerbate variations and the priority given to PDT.