|Year : 1979 | Volume
| Issue : 4 | Page : 152-156
Surgery for glaucoma
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Leydhecker W. Surgery for glaucoma. Indian J Ophthalmol 1979;27:152-6
| Are there conditions which always necessitate surgery ?|| |
The acute angle block glaucoma should always be operated upon. The recurrence rate of acute attacks, in spite of regular medical treatment, is at least 50% within 5 years, and few people can be relied upon to apply miotics for this length of time. If possible the 1.0. pressure should be reduced by drugs to less than 30 mmHg before commencing surgery.
The second eye of a patient with monolateral angle block glaucoma will usually have a narrow angle as well. In this case an acute angle block glaucoma will probably occur in the future, despite medical treatment. I would perform a prophylactic iridectomy.
A second condition which requires surgery as soon as the diagnosis is made, is hydrophthalmia. My surgical method of choice in eyes with a clear cornea is a deep goniotomy which I named angulozision. For this operation I constructed two instruments: a self-illuminating lens [Figure - 1] and a very slender perforated knife which keeps the anterior chamber deep during the intervention by a constant and regulated infusion of normal saline [Figure - 2]. The successrate in eyes with a clear cornea is 80% with 1-3 goniotomies.
Considerations for or against surgery in open angle glaucoma
The main disadvantages of miotics are the inconstant accommodative myopia in patients below the age of 50, ciliary spasms and the narrow pupil.
In some cases new developments can make medical therapy more acceptable. Pilocarpine is less disturbing in the form of Ocusert. Epinephrine gives less side effects in the form of Dipivalyl-epinephrine. Some beta-blockers cause no disturbance at all. These drugs will normalize i.o. pressure in cases where 2% Pilocarpine would have been used but they cause less discomfort. Carboanhydrase inhibitors are not useful for a lifetime treatment.
The individual tension tolerance cannot be predicted. In general I feel at ease when my patients have pressures below 10 mmHg and I feel uneasy when their pressures are occasionally above 30 mmHg, but even pressures between 20-25 mmHg can be too high for a patient with vascular sclerosis.
In addition to thinking about the tension tolerance factors, psychological or social aspects must also be considered when contemplating surgery. Patients who are clearly unreliable in their application of drops must be considered as being essentially without treatment for most of the time. Even apparently reliable patients forget to apply drugs more often than the doctors realize (30-50%).
Age only becomes a consideration in patients where life expectancy is short and here I would not advise glaucoma surgery unless absolutely imperative.
Will normalization of the pressure really stop further deterioration of the visual field? In my experience it will in the early stages practically always stop further field decay. In later stages it will at least slow down this decay.
There have been warnings against surgery if the visual field is already greatly constricted.
My experience is different. A very constricted field is one of the most important indications of the immediate need for surgery.
If there are in late cases haemorrhages on or near the disc I would think twice before undertaking surgery. Such optic nerves tend to deteriorate even after normalization of the pressure and this is more a vascular problem than one of glaucoma.
With what probability can we expect a normalization of i.o. pressure after surgery in chronic glaucoma 2 In approximately 70-80% of the first or second filtering operations a good surgeon can obtain normalization of the i.o. pressure without miotics and an additional 10% with miotics which were not sufficient to check the i.o. pressure before surgery. Success depends upon the skill of the surgeon. But there are patients with a strong tendency for cicatrization, on whom any filtering operation closes whatever the surgeon does.
| Choice of operations|| |
Practically all cases can be handled with a few types of operation. Peripheral iridencleisis is my first choice in open angle glaucoma. The contra-indications are; a) atrophy of the pigment layer of the iris as it occurs occasionally in the white races, b) strong neo-vascularisation of the iris of the angle, c) many peripheral synechiae. The peripheral iridenclesis is combined with an iridectomy if the chamber angle is very narrow. The advantage of the peripheral iridencleisis is that the anterior chamber is never lost during or after surgery. This is why cataract formation is not enhanced by this type of surgery. The inclusion of the peripheral iris pillar draws the iris upwards so that the inferior chamber angle in eyes with a narrow angle becomes wider.
The corneo-scleral trephining with a lamellar scleral flap is indicated in eyes with a strong iris atrophy, with synechiac in the chamber angle or with pre-operative i.o. pressures over 50 mm Hg in open angle glaucoma, or as the second operation if the first intervention closed by cicatrization. This operation is also preferred for most secondary glaucomas.
The filtering iridectomy of Preziosi-ScheieMalbran is my first choice in haemorrhagic glaucoma or in hydrophthalmia when goniotomies fail. The contra-indication is a narrow anterior chamber angle.
Cyclodialysis is indicated in aphacic glaucoma only. Strict contra-indications are when a patient over the age of 45 still has a lens or a narrow chamber angle.
Goniotomy or modification, the angulozision, is my first choice in congenital glaucoma with a transparent cornea.
Trabeculotomy is the first operation in congenital glaucoma with opaque cornea. If it fails, Scheies filtering iridectomy is performed.
Cyclodiathermic destruction of the ciliary body is done as a last resort if all other interventions fail. Diathermy is applied through the deeper layers of the sclera after preparing a 4/5 thickness scleral lamellar flap which is sutured back to its original position afterwards. In eyes with glaucoma and cataract I combine a corneo-scleral trephining covered by a scleral flap with the cataract extraction, if the vision is reduced by lens opacities to less than 0.5. If the i.o. pressure is only slightly elevated, e.g. below 35 mm Hg, it may be sufficient - to apply limbal cautery between two corneo-scleral sutures after the cataract extraction.
| Peripheral iridencleisis|| |
The conjunctival flap for peripheral iridencleisis or corneo-scleral trephining is prepared in the same way: only one upper quadrant is opened, the other one is left intact in case a second operation may be required later on. The curved conjunctival section starts at its apex 12 mm from the limbus and ends approximately 7 mm from the limbus. Tenon's capsule is excised if it is thicker than usual, or if a tendency for cicatrization is known from previous operations or from the other eye. The corneo-scleral limbus is exposed. The area where the incision is to be made is also very gently touched with a faint cautery so as to close the superficial vessels. The first part of the 6 mm long incision parallel to the limbus is made with a piece of razor blade, held obliquely at a tangent and starting approximately 1-2 mm from the limbus [Figure - 3]. The incision is directed towards the anterior chamber. When the incision is halfway through, the direction of the blade is changed and the rest of the incision done vertically through the corneo-scleral limbus. This change of direction, and the perforation into the anterior chamber should be in the region of Schlemm's canal. The iris periphery will prolapse and obstruct the wound. If more than the peripheral iris bulges forward it can easily be slipped back into the anterior chamber if gently touched with a spatula and one or two drops of aqueous are allowed to escape. In case of non prolapse, the peripheral iris is grasped by a fine-toothed forceps and incarcerated.
The incision of a double fold of the peripheral iris which has prolapsed into the wound is done by Vannas's scissors and starts at the right end of the wound if the surgeon is right-handed and sits behind the patient. The incision is directed downwards at an angle of 45 that is neither parallel with nor vertical to the limbus. The iris fold is incarcerated into the left end; of the limbal incision [Figure - 3]. It should be left intact as a double fold lined by the pigment epithelium inside. The pigment epithelium must be left intact.
The conjunctiva is closed by an uninterrupted 7.0 silk suture [Figure - 4]. Tenon's capsule is left unsutured. A steroid injection is made underneath the conjunctiva in a lower quadrant and steroids are also given 4-6 x daily as drops over the next week. The pupil is kept dilated for one week, even in cases of angle block glaucoma.
The i.o. pressure will not rise after this operation, unless cicatrization of the conjunctiva occurs. Antibiotics are usually not necessary.
Corneo-scleral trephining under a scleral flap. The conjunctival flap is prepared. A triangular lamellar scleral flap is prepared with a length of 5.5 mm on each side with a base of the same length at the limbus. The cornea is split at the base of the flap. A 1.5 mm trephining is done, ideally comprising Schwalbe's line and Schlemm's canal [Figure - 5]. A peripheral iridectomy is performed. Aqueous escapes now and the rest of the iris slips back. The apex of the triangular lamellar scleral flap is fixed with one 9.0 silk suture to the scleral. Sutures of the conjunctiva and further medical treatment as described in 4.
The combination of glaucoma surgery with cataract extraction needs a few words of description. We prepare a large conjunctival flap with the apex 12 mm from the limbus but comprising both upper quadrants. The corneo-scleral limbus is exposed. The conjunctiva is pushed back onto the cornea with a blunt instrument. The triangular lamellar scleral flap is prepared and trephining done as described. The limbus is opened by Castroviejo's scissors to half of its circumference, after one preplaced 9.0 silk suture has been inserted. After cryoextraction of the lens [Figure - 6] this suture is closed and the wound is closed by 5-6 more corneo-scleral 9.0 silk sutures, altogether usually 7 sutures. Peripheral iridectomy is performed now at the site of trephining. The triangular lamellar-scleral flap is replaced and its apex fixed by one 9.0 suture [Figure - 7]. The conjunctiva is closed by an uninterrupted 7.0 silk suture.
In this report I have expressed opinions based to my own work and also on a knowledge of the literature which, however, I have not quoted each time, as this would have made the report too long. This has been done in my textbook on glaucoma.
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7]