02 March 2017
Anaesthesia for eye surgery and eye treatments has certainly been transformed over the past century (plus) since Sigmund Freud – yes that Sigmund Freud(!) – experimented with cocaine paste to numb the human eye.
When I first started out in ophthalmology, around 30 years ago, general anaesthetic (GA) was common place for cataract surgery – with the attendant problems related to recovery from GA for the very elderly. Patients were often in a hospital for upwards of one week, since the surgical techniques were also very basic at that time. Now, with the latest minimally invasive femtosecond laser-assisted phakoemulsification cataract and RLE surgery, anaesthesia is also minimalist in the form of topical anaesthesia with mild sedation and intracameral anaesthetic.
General anaesthesia (now virtually eliminated, I think, over the past 30 years for most eye surgery) provides the surgeon with an immobile, unconscious patient who, of course, feels nothing and has no recollection of the procedure. This approach was replaced in the 1970s and 1980s with local anaesthetic injections around the eye. The most widely used local anaesthetic technique until recently was termed sub-Tenon’s anaesthetic in which an anaesthetic solution is injected beneath the delicate “skin” over the white of the eye. This was an excellent technique which is still in common usage. The anaesthetic, effectively “percolates” behind the eye affecting the various structures including the nerves, and can dramatically reduce eye movement, sensation (of course) and the awareness of the bright microscope light – which otherwise would be very dazzling.
Around 10 years ago the use of topical anaesthesia (anaesthetic eye drops only applied to the very surface of the eye) became more popular and widespread, and was commonly used with mild sedation to help relax the patient. The advantage of topical/eye drop anaesthesia is that there are no injections or sharp needles and therefore there is no bruising in or around the eye. The eyes look entirely normal after surgery (except for the dilated pupil, which lasts a day or two). The sedation element however is an important one and an experienced anaesthetist administers and supervises this aspect. The use of mild sedation makes the entire procedure very comfortable for the patient – and the lack of any sensation is virtually guaranteed by the use of anaesthetic actually put inside the eye once the procedure is underway (intracameral anaesthesia – literally “inside the chamber”).
The femtosecond laser:
The advent of femtosecond laser-assisted cataract and refractive lens exchange technology has allowed minimalist topical anaesthesia to be taken to another level. Because the laser performs several key steps – mainly creating a circular entry/opening into the cataract lens itself and softening the cataract, the surgeon is much less concerned about the patient possibly moving their eye during these important stages. With mild sedation and topical and intracameral local anaesthetic the whole process is well controlled with patients feeling almost nothing and also often having very little recollection of the process afterwards. Because the femtosecond laser technology speeds up the main operating theatre stage, topical local anaesthetic with mild sedation and intracameral anaesthetic has become a procedure of first choice for many surgeons. In addition, there is no need to pad the eye afterwards and the patient can see immediately – very often a revelation compared to their preoperative vision.
Because this combination of femtosecond laser technology and topical/sedation local anaesthetic is so minimalist, some surgeons are moving towards offering suitably selected patients surgery to both eyes at the same time. This is termed bilateral, simultaneous cataract or refractive lens exchange surgery.
There is no doubt that recent developments in modern cataract surgery and also in the latest anaesthetic techniques used have most certainly taken the whole field well into the 21st century.