Specialists attached to the Eye Hospital Colombo, have written the following explanation in response to our news item of the 28th March 2008 entitled "Docs reveal corrupt practices at eye hospital". The signatories to this letter are Drs C.P.Banagala, Charith Fonseka, Mangala Gamage, Muditha Kulatunga, Imalka Fonseka, Sujatha Pathirage, C.Sebanayagam, Manel Pasquel and Meena Mithrakumar The full text of the letter is as follows.

Cataract is an opacification of the human crystalline lens, which results in visual impairment. The only treatment for cataract is surgery. The existing lens is removed and it is replaced with an artificial lens.

Cataract removal in the 1980s and early part of the 1990s was done using a technique called extra-capsular cataract surgery. The eye had to be anesthetized by giving an injection around the eye, a 10 - 12 mm cut is made into the eye and the interior of the lens is expressed out leaving the capsule of the lens behind. The wound has to be closed with about 6 stitches. This can result in a change in the shape of the eyeball resulting in what is called surgical astigmatism. The strength of the eyeball is also weakened

Manual small incision cataract surgery is also done. It is technically difficult and is practiced only by a very few surgeons who are highly skilled at it.

Technology for cataract removal has improved and today the standard cataract surgery is by a method called phacoemulsification. Here ultrasound energy is used to break up the cataract and it is sucked out. It is possible to anesthetize the eye with eye drops without giving injections. The cut in the eyeball is only 2.2 - 3.5mm which does not require stitches. The advantages of phacoemulsification are very rapid visual recovery, the shape of the eye remaining unchanged, (therefore very little surgical astigmatism) and the strength of the wall of the eye is not reduced.

Once the human lens is removed, an artificial lens has to be implanted. There are two major types of implants. They are the rigid lenses, which require a cut of at least 7mm, to insert and usually requires to be stitched. This lens is made of a material called PMMA (commonly known as Perspex). The other type of lens is called a foldable intraocular lens which is flexible and can be folded and inserted through a 2.2 - 3.5 mm cut and does not have to be stitched. There are two major groups of foldable lenses. They are the hydrophobic acrylic and the hydrophilic acrylic. Hydrophobic acrylic lenses are mostly used but the new generations of hydrophilic lenses are increasing in popularity. Previously lenses were also made of silicone but they are not used very much now.

To implant a lens the power or the number of it must be calculated through a very complex process. This is called Biometry and is commonly known as scanning. First the cornea (front) of the eye must be measured by taking two readings at 90 degrees to one another. Then the length of the eyeball has to be measured by ultrasound or laser. These measurements as well as a unique number called the "A" constant which is specific for not only brand but also the model of the lens needs to be entered into a computer which will calculate the required number or power of the lens using a formula. There are several formulae and the operator has to decide which he will use depending on the readings that are obtained. This is also some times further complicated by a requirement to modify the "A" constant depending on the surgeon’s technique.

The cornea is measured with an instrument called a keratometer. The length of the eyeball is measured by one of 3 methods. The most accurate is called partial coherence interferrometry. It is non-contact and very fast. The second is called immersion biometry, which is almost as accurate but takes longer than laser interferrometry. Both these methods have an accuracy of greater than 90 %. The 3 d method is called contact "A" scan biometry which has an accuracy of about 60%.

It is important to note that because of so many variables, accuracy in biometry is not 100%. Accuracy levels of Biometry are at best only upwards of 90%.

Intraocular lenses are not provided in government hospitals. A limited quantity of Rigid PMMA lenses are provided by the Dept of Social Services and a few NGOs. A few foldable lenses are available through private donors, but they are mainly for children. -Patients for-cataract surgery are required to buy not-only the intraocular lens but also the special gel which is required to protect the interior of the eye when surgery is being performed. If a patient opts for a foldable lens then a prescription is given to purchase the above named items and a knife used to make the cut. The majority of foldable lenses implanted at the Eye Hospital are the hydrophobic acrylic lenses. There are only two brands of hydrophobic acrylic lenses sold in Sri Lanka. All most all other government hospitals (where foldable lenses are used) also use hydrophobic acrylic lenses as do almost all private hospitals in Sri Lanka. This is also the pattern worldwide.

It can be questioned as to whether a generic prescription for an intraocular lens can be issued. If the lens is being paid for by the patient the patient should decide whether it is a rigid or a foldable. Even then if the brand and the model needs to be selected because of the "A" constant (the unique number for each model of each brand of lens). In the case of foldable lenses there is also a factor of the surgeon’s familiarity with the implantation process where one or the other brand may be preferred for ease and experience of implantation, which makes results reproducible. Some surgeons may use both type of lenses with ease. This again is seen in all government and private hospitals in Sri Lanka as well as worldwide. So brand and model of the lens must be known before initiating biometry. Otherwise (even if surgeon familiarity is left out and this is a very important factor in outcome) biometry must be done for several models of several brands. Then again there is a dilemma as to who decides. Is it the patient the seller or the doctor.

At the Eye Hospital unfortunately, only the contact A scan is available. The hospital has requested funds to purchase a new scanner but due to financial constraints we may get it only this year. Patients who purchase foldable lenses get biometry or scanning done outside for 4 reasons. (i) It is free of charge to the patient (ii) it is more accurate because both laser interferrometry and immersion biometry are available (iii) if the seller makes a mistake in the biometry or scanning they are held accountable (iv) lastly eye hospital finds it difficult to cope with the demand. This is done in the best interests of the patient, because it is more accurate and most of all it is free.

The hospital in spite of many shortcomings not only strives to achieve a quality in cataract surgery comparable to private hospitals, but also to keep the waiting lists short. The best technology is used. The best technology is not the preserve of the rich who can afford to have cataract surgery at private hospitals. This is the only government hospital where numbers are not restricted in clinics. It is very unfortunate that serious allegations have been leveled at the Eye Hospital Doctors. It is very easy for the doctors to take defensive positions and issue only generic prescriptions. This will only cause severe hardship for patients, difficulty for surgeons, slow the surgical output and increase waiting time for cataract surgery. This will force at least some of the patients to have cataract surgery done at private hospitals. Who would benefit from that?

But by far the greatest damage is the undermining of public confidence in an important public institution. A Public institution which is the biggest provider of eye care in Sri Lanka. An Institution which is the main postgraduate training center for Ophthalmology.

There may be shortcomings at the Eye Hospital, but it is to be expected, as it is an institution in a developing country, which provides a free, and comprehensive eye care service for an unlimited number of patients. However it is much better than the Public Eye Hospitals of other developing countries even with a significantly higher GDP than Sri Lanka.