Newsletter Spring 2015

Dear patients and friends,

During the past few months, things have continued to tick at the usual rate, so nothing changed there! Many of you must have heard of Barts in the news recently, and we are all very hopeful that this will spark further investment and support from the powers to be. We are certainly very dedicated in the Whipps Cross eye department to ensure that we continue to provide a high quality and efficient local service, which I firmly believe in and I am delighted that my retinal practice continues to occupy much of my time. I have also taken up the role of being Clinical Governance Lead for Ophthalmology at Barts, a most interesting look into the world of patient care. In the private sector, I have moved much of my Thursday evening clinic to the London Medical at 49 Marylebone High Street and delighted to say that this is working very well. The major advantage that the London Medical offers my patients is the fantastic technical support staff for imaging including Heidelberg OCT and Topcon retinal photography as well as having on site various lasers to serve different purposes. To close the loop, I also perform much of my injections at the London medical, so patients can be seen and managed as a one stop.

I was supposed to discuss the implantable telescope implant in this letter, but this project has been slow to move forward and I have therefore changed the topic to “how can I get rid of my glasses, what about lens implants?”

Hadi Zambarakji MB ChB, FRCOphth, D.M
info@retinacare.org.uk
Spire Roding Hospital, Roding Lane South, Ilford. IG4 5PZ.

How can I get rid of my glasses, what about lens implants?

Spectacles are usually prescribed to correct a refractive error, this includes myopia (short sight), hypermetropia (long sight), astigmatism or presbyopia. In young patients with no other ocular findings, this is a relatively simple matter using either spectacles or contact lenses. Those with higher degrees of refractive error may need the have high refractive index lenses to reduce the thickness of the spectacle lenses to make them thinner and lighter. Astigmatism is said to be present when the corneal shape (the cornea is the clear anterior part of the eye) is such that it is more curved in one meridian than another, sometimes the analogy is made with the cornea looking more like a rugby ball than a football (but this is a slight exaggeration). Astigmatism can also be corrected with spectacles or contact lenses, but in some cases of complex alterations in the corneal surface as seen after severe trauma, irregular astigmatism can be more difficult to fix and often would need contact lenses. Finally, lasers can of course, correct all the above forms of refractive errors, and for laser refractive surgery, you would need to see a refractive surgeon! Presbyopia however, is the loss of accommodation of the natural lens, this is when the patient finds that his arms are not long enough to read the paper. This usually starts in the 40’s, but those with myopia are already focused for near, so they are able to read for near without spectacles and those with hypermetropia will need reading spectacles much at an earlier age than myopes.

For patients who have reduced vision due to cataract in addition to wearing spectacles, it is possible to remove the cataract and correct the refractive error by way of microincision phaco cataract surgery with lens implantation. In order to achieve spectacle independence, one would therefore choose the appropriate lens implant power in addition to correcting astigmatism. Astigmatism correction is achieved by using a “toric lens implant” that would need to be positioned in the eye in a particular position in order to correct the astigmatism. These goals are achieved using a “monofocal lens implant”, also referred to as a standard lens implant, although the toric lens is not strictly speaking a standard lens. The monofocal lens delivers high contrast images over a limited range of focus, so if the lens power chosen is aimed for distance vision, there will be limited near vision and reading spectacles would be needed, just like you would in presbyopia. If the lens power chosen is aimed for near vision, the opposite would happen and spectacle correction would be needed for distance vision.

“Multifocal lens implants” however were developed to achieve distance, intermediate and near vision. They do this using different mechanisms but the process of light scattering results in reduced contrast sensitivity and generates some degree of glare. This is usually manifest as halos of light around bright lights, glare, and sometimes double vision or ghosting around images all of which can be a problem for night driving. Much of the current research is therefore focused on optic design to minimize unwanted visual symptoms. The trade off between gains in spectacle freedom and optical side effects of multifocal lens implants remains widely recognized and one to bear in mind if choosing to have a multifocal lens. However, recent studies that have looked at patient satisfaction and night symptoms after multifocal lens implant surgery have shown a high patient satisfaction (over 90%) and that most patients would recommend the procedure to a friend/relative, but glare can be quite bothersome in up to 5% of patients. On rare occasions, intolerance to night symptoms can result in the need to remove the multifocal lens and exchange this with an alternative monofocal lens. I have personally been using the Oculentis Comfort multifocal lens recently, which achieves distance and intermediate vision rather than close up reading vision, which I may at times combine with low myopia in one eye only to help with near vision and have achieved very satisfactory outcomes. Most patients with this lens will have good distance and intermediate vision, and some degree of near vision for most tasks such as reading a menu or price tags in the supermarket, although reading spectacles are needed for reading a book or a newspaper. One other method of achieving spectacle independence is called “monovision”. Some of you may already do this by wearing contact lenses, which correct one eye for distance and the second eye for near. The same can be done at the time of microincision phaco cataract surgery by correcting one eye for distance and one eye for near (the second eye is usually rendered myopic around -2 to -2.5 D). I have personally found this a very satisfying means of achieving spectacle independence in those who have already tried monovision contact lenses and demonstrated before surgery tolerance to monovision. One variation on monovision is micro-monovision, that is to correct the near eye to low myopia (-1 D), which minimizes the difference between the 2 eyes and is usually well tolerated but achieves intermediate vision rather than reading vision. The advantage of the monovision technique is that it utilizes monofocal lens implants, which achieve better contrast sensitivity than multifocal lens implants. Finally, “accommodating lens implants”, have been tried but have had a much lower uptake, I therefore include them for the sake of completion but I have not been a particular fan.

So who should not have a multifocal lens implant? Those with any form of retinal problems who would therefore be more sensitive to glare and problems at night. For younger patients (under 40 years), I would usually recommend seeing a refractive surgeon for consideration of laser refractive surgery, unless they have significant cataract. Patients who are happy wearing reading spectacles may not necessarily need to have a multifocal lens implant as reading spectacles are a very effective means of correcting reading vision.

The questions to be asked before having phaco cataract surgery (if you wish to have a with multifocal lens implant) are therefore as follows:

How do I spend most of my time (outdoors/indoors, reading books/computer screen)?

Is my goal to be totally spectacle independent?

Am I happy to wear reading spectacles for small print (books/newspaper)?

Am I happy wearing intermediate distance spectacles for computer work, cooking, reading music?

Do I have significant astigmatism?

Do I suffer with glare and night symptoms?

Do I have a retinal problem?

No comments yet

Leave a comment