Experts’ opinion – Case 9

In addition to answering the questions posed to our members, our Experts were also asked the following questions :
1. In case of blind eye which is most frequently chosen : binocular or monocular surgery? Why?
2. What parameters would you consider when performing strabismus surgery on eyes with phthisis bulbi?
3. Have you had any problems with a patient while operating on the healthy eye in addition to the blind eye?
4. What would be the maximum surgery to perform both resections and resection or muscle folding in case of unilateral surgeries?

Dr. Quah Boon Long

The “left inferior oblique overaction” looks like a pseudo-inferior oblique overaction due to the V pattern XT and left ptosis. If you look carefully, the inferior limbus of the left cornea seems to be at same level as the right inferior limbus on right and right-and- up gaze.
(1) Would you perform surgery on phthisis bulbi eyes? (a) Yes (b) No?
In a case like this, I would consider surgery for psychosocial reasons and to enhance the patient’s employment prospects if conservative measures such as cosmetic contact lenses or ocular prosthesis are not suitable.
What parameters would you consider when performing strabismus surgery on eyes with phthisis bulbi?
When performing strabismus surgery on eyes with phthisis bulbi, there is always the risk of further disrupting the blood supply to the eye (anterior segment ischemia) and aggravating the phthisis bulbi. The outcome in terms of ocular alignment can also be unpredictable, and the patient must be advised that further deviation of the eye over the long-term is still possible. I would hence choose rectus muscle plication over resection, and perform muscle recession on adjustable sutures to have a better chance of at least a good initial post-operative ocular alignment.

(2) What technique would you choose to perform a muscular reinforcement?
(a) Muscle folds (b) Muscle Resections?
I would favour a large medial rectus muscle plication over medial rectus muscle resection to minimize the risk of anterior segment ischaemia in the eye with phthisis bulbi. The risk of anterior segment ischaemia in 2 recti muscle surgery for normal eyes is almost negligible, but in this particular case it makes sense to minimize such a risk as far as possible.

(3) In case of blind eye which is most frequently chosen : binocular or monocular surgery? Why?
In patients with deep amblyopia of an eye or blind eye I prefer to perform monocular surgery on the eye with poor visual potential in order to avoid surgical complications on the normal seeing eye.

(4) Have you had any problems with a patient while operating on the healthy eye in addition to the blind eye?
There are rare instances where I need to perform strabismus surgery on both the healthy and blind eye of a patient. The patients are understandably usually reluctant to have surgery on their good eye, but if the reasons and advantages for bilateral surgery are explained and weighed against the very low risk of serious eye complications of strabismus surgery, the patient will consent to the surgery. I have not had any complications so far with bilateral strabismus surgery in patients blind in one eye, but I rarely perform such surgeries.

(5) What would be the maximum surgery to perform both resections and resection or muscle folding in case of unilateral surgeries?
In unilateral surgeries for exotropia, maximum lateral rectus muscle recession I would do is 11-12 mm (I put the muscle on adjustable suture whenever possible). The maximum medial rectus muscle resection I would do is 10 mm. For large medial rectus muscle plication, the patient must be informed that a bump from the plication can be unsightly initially. For large monocular recess/resect surgeries, the patient must also be informed of the postoperative limitation in ocular motility and possible narrowing of palpebral fissure.

 

Dr. Manoj Parulekar

(1) Would you perform surgery on phthisis bulbi eyes? (a) Yes (b) No?
Yes, I do offer surgery on phthisical eyes.
What parameters would you consider when performing strabismus surgery on eyes with phthisis bulbi?
Several factors need to be considered when planning surgery on a blind/poorly sighted eye : (i) IOP – low IOP indicates poor health of the eye. As the blood supply to the anterior segment is carried with the extra-ocular muscles, any muscle surgery will deprive the anterior segment (ciliary body) of blood supply and might induce more phthisical changes. For this reason, I prefer plications over resection. I also use a vessel sparing technique (using the microscope) when performing recession in such cases. (ii) Another consideration is that the eye is soft, and passage of sutures through the sclera can be tricky in such cases, with greater risk of perforation. (iii) Previous surgery, especially Retinal detachment repair, presence of silicone oil/buckle, previous penetrating eye injury (scleral laceration), orbital foreign body. (iv) Previous strabismus repair- this might limit the amount of surgery possible if the muscles have already been recessed. (v) Axial length and condition of the sclera- The apparent angle of squint is minified in smaller eyes, and magnified in abnormally large eyes. Large blind eyes e.g. with staphylomatous corneal opacities might require more surgery to give a good cosmetic result. The sclera can be very thin in abnormally large eyes, with greater risk of scleral perforation when passing sutures. (vi) The presence of a vertical deviation especially DVD in addition to horizontal deviation. It is not uncommon for such eyes to have a Dissociated vertical deviation. Inferior obloique anteriorisation is a very effective procedure in such cases, with low risk and significant gain

(2) What technique would you choose to perform a muscular reinforcement?
(a) Muscle folds (b) Muscle Resections?
I prefer plications

(3) In case of blind eye which is most frequently chosen : binocular or monocular surgery? Why?
I prefer monocular surgery. In case of a blind eye, which is most frequently chosen, I would choose monocular surgery for several reasons : (i) Although the risk of damaging vision from squint surgery is low, it is not zero. The consequences of losing vision in the remaining seeing eye as a result of complications would be devastating. (ii) Blind eyes are often (but not always) divergent, often with very large angles. Performing extra-large recessions and resection/plication can result in significant limitation of the range of movement of the operated eye. This will have no negative consequences if performed on the blind eye. Indeed, performing extra-large plication/resection can provide longer term results as the induced limitation of abduction in divergent squints reduces the risk of long term drift.

(4) Have you had any problems with a patient while operating on the healthy eye in addition to the blind eye?
The usual scenario in which I have to operate on the better seeing eye, is when operating on adult patients who have an amblyopic eye and have undergone several strabismus procedures in the past. I have not encountered any problems in such cases yet, but there is always a small risk.

(5) What would be the maximum surgery to perform both resections and resection or muscle folding in case of unilateral surgeries?
I prefer plications over resections to minimise disrupting the anterior segment circulation. I have performed up to 12 mm resections and 14 mm plications on medial or lateral rectii. When performing such large plications/resections on the lateral rectus, it is important to separate the inferior oblique from the lateral rectus to ensure it is not included in the scar, as this will result in a progressive consecutive exotropia. I will recess the lateral rectus beyond the equator i.e. >16 mm from the limbus if required. For the medial rectus, I do not recess beyond 13 mm from the limbus as the risk of consecutive exotropia is very high. If the muscle has already been maximally recessed, I will consider central tenotomy to maximise the result, and also a conjunctival recession if there is contracture. Such large amounts of surgery will inevitably result in restriction of range of movement of the operated eye, which might contribute to long term stability of the surgical result.

 

Dr. Hyun Taek Lim

(1) Would you perform surgery on phthisis bulbi eyes? (a) Yes (b) No?
Yes; Sometimes we need to perform strabismus correcting surgery on the phthisic eyes, because the majority of the patients with phthisical eyes want to improve their ocular cosmesis.
What parameters would you consider when performing strabismus surgery on eyes with phthisis bulbi?
Measurement of the strabismus angle at both distance and near is of paramount importance. Sometimes you may have different amount of angle between distance than near measurement. For this setting, it would be appropriate to recommend adjustable surgery or adjustment of your amount of surgery to get better postoperative alignment. For example, when I have smaller angle of exotropia at near compared with distance fixation, I perform lesser amount of medial rectus resection than that of my conventional resection for the patient’s maximal distance angle. The other thing that I consider is to determine whether there is any restriction of eye movement. If the limitation of eye movement is suspected, preoperative or intraoperative forced duction testing is imperative to evaluate the degree of limitation. If you have severe limitation of eye movement or strabismus fixus-condition, you need to perform supramaximal recessions of recti or even complete tenotomies in selected cases. In addition, one may assess the degree of enophthalmos when considering strabismus surgery for phthisical eyes. If you have significant enophthalmos, the amount of resection surgery should be reduced to avoid further retraction of the globe.

(2) What technique would you choose to perform a muscular reinforcement?
(a) Muscle folds (b) Muscle Resections?
I prefer muscle resection to muscle plication. I have a concern about conjunctival bulging possibly occurring after plication surgery. I don’t think the plication surgery has an actual advantage over resection surgery.

(3) In case of blind eye which is most frequently chosen : binocular or monocular surgery? Why?
With rare exceptions, I prefer to perform unilateral surgery on the amblyopic or blind eyes. Although serious complications of strabismus surgery are quite infrequent, the sequelae may be profound in the setting of one healthy eye. I think we can obtain practically sufficient results with only unilateral surgery rather than bilateral or contralateral eye surgery in most cases.
In this setting of surgery for sensory strabismus, I perform unilateral surgery on the visually impaired eye, with very rare exceptions. The main reason for selecting unilateral surgery is due to serious surgical complications possibly occurring when we perform surgery on the healthier eye. Although the rates of strabismus surgery are very low, the results may be drastic and ominous, especially when you get postoperative endophthalmitis, retinal detachment, or anterior segment ischemia. In order to avoid the complications, I perform unilateral surgery on the poorer eye. In addition, I think most strabismus surgeons can achieve sufficiently good cosmetic results with the unilateral poorer eye surgery without performing bilateral or contralateral eye surgery even in severe cases of sensory strabismus.

(4) Have you had any problems with a patient while operating on the healthy eye in addition to the blind eye?
No, I don’t perform healthy eye surgery in this setting. When you try to do the strabismus surgery on healthy eye, extra-caution is needed to avoid scleral perforation in scleral suture procedure as well as disinsertion of the recti.

(5) What would be the maximum surgery to perform both resections and resection or muscle folding in case of unilateral surgeries?
The amount of maximal surgery may depend on multiple factors including the degree of extraocular movement restriction, adhesion or fibrosis around the extraocular muscles, the size of the eye globe, and the amount of the previous strabismus surgery, if any. In general, in my experience, maximal recommendable amount of horizontal recti recession would be up to 10 to 12 mm by scleral suture technique, while the amount of resection up to 8 to 10 mm for horizontal recti. Larger than that, I think it could induce unfavorable results such as iatrogenic restriction of the eye movement, further narrowing of the palpebral fissure, and significant retraction of the globe.

 

World Society of Paediatric Ophthalmology and Strabismus
Temple House, Temple Road, Blackrock, Co. Dublin, Ireland

Phone:+ 353 1 288 3630
Fax:+353 1 209 1112
Email:wspos@wspos.org

World Society of Paediatric Ophthalmology and Stabismus is a registered Charity with the U.K. Charities Commission (Charity Registration Number ;1144806) (Registered November 2011)

Site Developed by Agenda Communications | Copyright 2018 | Privacy Policy