Virtual Surgery: Construction of a Training Program and Analysis of Significant Factors for Operating Performance

Background:

Operations in the retina and removal of the vitreous body (vitrectomy) is a procedure that is in rapid growth. Demographic mix and a rapidly increasing incidence of lifestyle-related diseases such as diabetes mellitus leads to increased operational need [1]. Causes of vitrectomy include bleeding in the vitreous of the eye, retinal detachment, a hole in the macula of the retina (macular hole) and removal of connective tissue (epiretinal membrane) at the macula.

Vitrectomy was previously associated with high risks and were therefore only performed in special cases, but in recent years the operational results have been markedly better - not least due to the introduction of technological advances such as smaller and better instruments. Nevertheless, it is a type of operation that the surgeon requires a long training and an increased risk of operative complications in the early stage. For this reason, virtual surgery is suited to help training and maintaining operational skills [2, 3].

Research Unit of Ophthalmology at Odense University and Southern University received in 2007 a grant from the Velux Foundation for obtaining a EyeSi (eye surgical simulator) Surgical Simulator (VRMagic Gesellschaft mit beschränkter Haftung (GmbH), Mannheim, Germany). This surgical eye simulator has subsequently been a great joy for eye surgeons from across the country who have used the machine to train and maintain operating procedures.

The machine can be used both to train cataract operations, as well as responses in the eye's posterior section (vitreoretinal surgery) surgery of the vitreous body and retina. There is an increasing research activity within EYESI-based virtual eye surgery [4-6], but so far this reserved for training in cataract operations. The investigators have, for example, previously could demonstrate that repetitive training in cataract surgery promotes the surgical learning and enhance the qualifications of future eye surgeons [7]. Subsequently, another Danish group published proposals for specific simulation pass requirements [8], and simulation training is subsequently introduced as part of the training of future cataract surgeons in the country.

There are no previously published research in virtual vitreoretinal surgery, but this is nevertheless vital to better surgical training. The vitreoretinal training modules include exercises in varying degrees of difficulty in numerous areas such as Navigation Training, Forceps Training, Anti-Tremor-Training, bimanual Training, bimanual Scissors Training, Laser Coagulation, Posterior Hyaloid Training, Epiretinal Membrane Peeling, Internal Limiting Membrane (ILM) Training and Retinal Detachment. Due to the many potential exercises it is important to develop a vitreoretinal training program which includes relevant modules at the right level of difficulty.

One of the main requirements for such a program is that it should exhibit high construction validity [9]. Meaning that the program must be able to measure the wanted, which in this case is surgical skills in groups with different levels of competence. It must, in other words, be possible to differentiate trained vitreoretinal surgeons from untrained surgeons. From this it will be possible to develop reference scores, and the program can be implemented in surgical training course.

Many surgical disorders - such as retinal detachment - progresses with time, and it is often not known when to ideally operate [10]. On the one hand, it may be best to operate early and thereby reduce the risk of disease progression before surgery. On the other hand, it is also important to take into account factors such as the presence of the correct operational expertise as well as the surgeon's fatigue and stress levels.

Conditions as last-mentioned clearly is difficult to test clinically and virtual surgery thus allows to design studies that safely allows for testing conditions as sleep deprivation and other operational distractions.

Purpose:

The purpose of this study is 1) to facilitate the training of future vitreoretinal surgeons by introducing a virtual training program with high construction validity, and 2) to clarify which external conditions affects the performance of trained operator using the virtual training program.

Substudy A:

From the training sessions, simulation manuals and guidance from vitreoretinal surgeons, proposals for a virtual vitreoretinal training program is composed including relevant modules in appropriate degree of difficulty.

This program is tested following three groups:

1. Group with trained vitreoretinal surgeons (n = 5).
2. Group with future ophthalmologists in training (n = 10).
3. Group of medicine students with limited knowledge of the anatomy and pathology (n = 20).

Each group should go through the program twice with one to two weeks apart, and the results from the second training session is determined. Subsequently the individual modules construct validity is evaluated, assuming that a given module exhibits high construction validity, if the median score for group 1 is higher than that of group 2, which is in turn higher than that of Group 3 (tested by Cuzicks test for trend).

Modules with high construction validity is then included in the final model.

Substudy B:

Based on the constructed program in substudy A, five subjects goes through an intensive training program, which terminated when they achieve the same target score as Group 1 in substudy A. The target score is now used as reference for subsequent exercises.

The subjects then conducts the training program under the influence of the following operational challenges:

1. Operation with non-dominant hand.
2. Operation with auditory distraction.
3. Operation during nighttime sleep.
4. Operation after 12 hours of fasting for solid food.
5. Operation after 24 hours of sleep deprivation. It is then calculated which of the five programs, which results in a modified test score compared to score target (tested by Wilcoxon matched signed rank sum test).