A Feasibility Study to Develop a Protocol for Functional Lacrimal Magnetic Resonance Imaging

Lacrimal Duct Obstruction, Lacrimal Stenosis

Watering eyes (epiphora) is a very common ophthalmic condition. It is frequently caused by dysfunction of the lacrimal (tear) drainage system which is the 'pipework' that takes tears from the eye to the nasal cavity. If the system is completely blocked then the patient is offered surgery to unblock or bypass the obstruction. However, the system is often either partially obstructed, or there is tear drainage delay despite there being no apparent obstruction (functional obstruction). Currently this is investigated with two separate scans, conducted at different times in different departments (CT and nuclear medicine). These are dacryocystography (DCG) and dacryoscintigraphy (DSG) and both are required as they have different limitations and benefits. Moreover DCG is a CT scan that uses radiation. Functional magnetic resonance dacryocystography (MR DCG) is increasingly widely used in other fields of medicine (e.g. cardiology) because of the increasing acquisition speed and resolution of MRI scanners in recent years. The investigators anticipate functional MRI of the lacrimal drainage system (i.e. scanning as eye drops are instilled and pass down the system) will overcome the shortcomings of DCG and DSG, by simultaneously providing both good anatomical detail and physiological images. Various methods of MR DCG have been described in the literature and there is no standard protocol for this procedure as of current. In this study, the investigators aim to develop a protocol for MR DCG that can be used in routine radiological practice in place of DCG and DSG and get pilot data on tear drainage in participants with known delayed tear drainage and controls with normal tear drainage systems.

Tear drainage delay is a common problem that causes a watery eye. This can impair activities of daily living such as reading and driving, can be a huge nuisance requiring continual dabbing with a tissue and can cause infections and abscesses of the tear drainage system. The current, standard investigations for tear drainage delay have significant limitations with two separate scans in separate departments being required. A functional MRI scan would be able to combine these two scans and provide both better anatomical and functional detail than each one respectively. This would have several major benefits: 1. Improved diagnostic information to guide the treatment choice 2. Reduced scan resource usage as one scan would provide all the required functional anatomical and functional information. 3. Improved patient convenience 4. Improved safety as radiation is used for CT DCG, where MRI The study involves investigation of both controls with normal tear drainage and individuals with known tear drainage delay. Both groups are required for the development of the protocol as the speed of tear transit will differ greatly which will facilitate optimisation of the MRI scan protocol. This will also provide preliminary data on the speed of tear passage in a normal lacrimal drainage system and in an impaired system. Several other functional lacrimal drainage MRI studies have been done. However, a clear protocol has not been developed and there is no data on normal and abnormal MRI appearances and tear transit times. The normal standard of care will not be delayed by this investigation as it will be conducted while patients are awaiting other lacrimal investigations (DCG and DSG) or lacrimal surgery, none of which would be affected by this study.

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