Cataract Surgery
Cataract Surgery
Cataract refers to ‘clouding’ of the natural lens in the eye. It may involve one or both eyes and often develops slowly with age. It varies in degree of cloudiness and depending on the extent of the cataract, it affects vision in various ways. Symptoms may include blurred vision, faded colour appreciation, haloes around lights, glare, difficulty with night vision, seeing double out of one eye.
There are many cause(s) but the eventual outcome is reduced vision. When cataract starts to interfere with one’s ability to function, whether its work or social, the only option available is cataract surgery. Cataract surgery is generally performed under topical anaesthetic (anaesthetic eye drops) with mild sedation given by the anaesthetist as a day procedure.
Before cataract surgery is performed, it is firstly confirmed by the surgeon; then an essential measurement of the eye called biometry performed so that the appropriate intraocular lens power can be determined for each eye. An OCT (Optical Coherence Tomography) of the eye is also performed which is a special high resolution ultrasound to study the macula, making sure that there is no other problem which may be causing the reduced vision.
In hospital, the eye is prepared for surgery where dilating drops are given by the nurse. Surgery involves removal of the cloudy lens by phacoemulsification (high frequency ultrasound) and the new intraocular lens is inserted.
Surgical time usually takes less than 10 minutes but please be mindful that you are undergoing an eye operation and ‘short surgical time’ does not equate to ‘small / easy’ operation. There are several surgical steps involved and one may have heard of laser- assisted cataract surgery. The misunderstanding that surgery is performed purely by laser is NOT true.
In simple terms, imagine a grape with an outer skin and inner soft flesh; the grape skin is the lens capsule and the inner flesh the cloudy lens. The aim is to remove all the inner fleshy grape (lens) through a small opening on the grape skin. A small round opening is created on the grape skin either with a very fine needle, a special pair of forceps or for some surgeon, femto-laser.
Next step is to separate the grape skin (capsule) from the underlying flesh (cataract) so that the whole fleshy grape is free to move about. Using phaco / ultrasound, the cataract is then reduced to tiny fragments and sucked out. Once completed, the intraocular lens (folded in half) is introduced into the grape skin ‘bag’ through the round opening and it then unfolds to its full size which is usually around 12mm in length.
Laser assisted cataract surgery introduces femto laser to create the initial capsular opening and segment the cataract into several fragments. The rest of the operation is exactly the same.
The only difference is that femto laser is used only for the initial step of the whole surgery and additional cost to the patient! This laser-assisted cataract surgery has not been taken by many surgeons as we know that there is no additional benefit in the visual outcome.
Risks exists and include infection (endophthalmitis, less than 0.1%), bleeding (haemorrhage), inflammation (iritis), low or high intraocular pressure, retinal detachment, swelling at the macula (cystoid macular oedema) to name a few. This is not by any means an attempt to explain in detail the clinical and surgical aspects of cataract and surgery.
Lastly, the capsular support which holds the intraocular lens can become cloudy over time (months / years) ie posterior capsular opacification. When this occurs, vision becomes blurred or cloudy and once confirmed to be the issue, simply YAG laser capsulotomy can be performed to clear the cloudy capsule away and restore vision.
Below is a link to the Australian and New Zealand College of Ophthalmologist (RANZCO) providing a brief explanation on cataract surgery.
Another source of information can be found in the link below to the American Academy of Ophthalmology.
https://www.aao.org/eye-health/diseases/what-are-cataract
There are many different types of intraocular lens. You should discuss this with your surgeon and essentially there is the mono-focal and multifocal intraocular lens. Within each category, there are many different lens designs and the surgeon will use the lens which he or she is experienced and comfortable with.
Refractive Lens Exchange
In a different group of patients where one may not necessarily have a symptomatic cataract, still with a fairly clear natural lens but have been reliant on spectacles or contact lenses (ie myopic or short-sighted, hypermetropic or long-sighted, or presbyopic ie needing reading glasses). There is a desire to be freed from spectacles or contact lenses.
The same cataract surgery applies except the reason for surgery is refractive.
One implants a form of multifocal or extended depth focus intraocular lens with the aim of achieving good vision ranging from reading to distance. Following satisfactory pre-operative normal eye examination and uneventful surgery, there is a high probability of achieving spectacle independence.
There are many different forms of implants and the selection choice varies between surgeons.
My current selection of lenses is shown below, which I have been involved for many years (this will vary in time as new developments in lens technology may change selection decision) and I have included a link for each lens below, just click on the image.
AcuFocus (small aperture IOL) is a new player in the field of intraocular lens and I have been involved in implanting this lens over close to 2 years now.
I was invited to provide a surgeon’s prespective and there is a link to the article (click on the picture of the lens below) published in September 2019 with contributary comments from myself and other Australian surgeons, having involved in over 30 bilateral implants and 60 unilateral implant at the time of publication.
For those interested in refractive lens exchange aiming to achieve ‘spectacle independence’, there is a wide selection of implants and it is best that you discuss your needs with your surgeon. Over the years, the design in the development of these implants continue to improve, and the visual outcome is generally very good.
Paediatric cataract is uncommon and affects newborn and young children due to different underlying reason(s).
The management of paediatric cataract depends on several factors including age of onset, the degree of cloudiness (potentially amblyogenic), any associated ocular or systemic condition which might affect timing of surgery.
Some newborns need to undergo urgent surgery and the cloudy lens is removed but no intraocular lens is implanted till at a later stage. A contact lens is used post-surgery to aid vision. Associated complication such as glaucoma is much higher when surgery is performed at a much earlier age (under 6 months) When to implant will also be dependent on age of the child and experience of the surgeon with regards to which type of intraocular lens to consider.
The debate of the most appropriate lens power continues as it is difficult to calculate and predict eye growth but a child’s eye reaches adult axial length usually around 2 years old, any implant may not necessarily correct the child’s refractive error and thus glasses is still required.
I do believe any child beyond 5 years old and requires cataract surgery, there is a strong argument for implanting a multifocal intraocular lens, assuming all other ocular parameters are within normal limits.
To date, I have implanted multifocal and multifocal toric intraocular lens in 9 patients under 16 years old (unpublished data) and all are functioning well visually with all able to read without glasses.
The following links provide more in-depth information for those interested to read further.
https://www.aao.org/eye-health/diseases/what-are-pediatric-cataracts
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4293928/
https://www.aao.org/disease-review/pediatric-cataracts-overview
This picture shows post lensectomy with no intraocular lens planned at time of surgery
Currently most paediatric cataract surgeries are performed at Perth Children’s Hospital, which I am currently a Consultant Surgeon at the Ophthalmology Department.