Understanding the management of ptosis.
Dispensing opticians ***
Ptosis is a drooping of the upper eyelid due to paralysis, disease, or as a congenital condition and occurs commonly with ageing (see Figure 1). Normally, the upper lid rests approximately 2mm below the upper limbus when the eye is looking straight ahead; the lower lid normally rests at the lower limbus. The vertical palpebral fissure for adult men is between 7-10mm, and for women it is 8-12mm. (1) In ptosis, the eyelid may droop just a little, or so much that it covers the entire pupil. Ptosis can, therefore, restrict or even completely block vision, particularly in the superior field. Ptosis may result from levator palpebrae superioris (LPS) maldevelopment present at birth, or acquired dissociation or weakening of the LPS with age.
Although ptosis is commonly encountered in patients of all ages, there is a paucity of data regarding the prevalence and incidence of ptosis globally. There is no known ethnic or sexual predilection. However, there have been few isolated studies on the epidemiology of ptosis. A study conducted by Baiyeroju et al, in a school and a private clinic in Nigeria, examined 25 cases of ptosis over five years and found that 52% of patients were less than 16 years of age, while only 8% were over 50 years of age. There was a 1:1 male to female ratio in the study with the majority (68%) having only one eye affected. The most common cause of ptosis in the study was congenital (56% of patients). The prevalence rate in the school survey was found to be 1.2%. Ptosis is relatively commonplace in the elderly population, particularly after intraocular surgery; this is probably due to the stretching or disruption of the levator muscle when the eyelid is retracted with a speculum during surgery. (2) One study looking at 400 people that were aged 50 years or older in the UK discovered that 11.5% had some form of ptosis and that the prevalence of ptosis increased with age. (3)
Signs and symptoms
Commonly, the patient may complain of cosmetic issues when presenting with ptosis, or difficulty keeping their eyes open and may tilt their head back or repeatedly raise their eyebrows in an effort to lift the eyelids. When the person is tired, the drooping may be more noticeable as the muscles fatigue. (4) The drooping eyelid narrows the palpebral aperture, which makes the affected eye appear smaller than normal. (5)
The aetiology of ptosis can be congenital, mechanical, myogenic, neurogenic or traumatic. In cases of Horner's syndrome, there may be partial ptosis, miosis, anhidrosis, with or without enophthalmos.
Ptosis occurs due to dysfunction of the muscles that raise the eyelid or their nerve supply (oculomotor for the LPS and sympathetic nerves for the superior tarsal muscle). Ptosis is more common in the elderly, as muscles in the eyelids may begin to weaken. Congenital ptosis occurs when the LPS has failed to develop properly and is, therefore, not able to lift the eyelid properly. Ptosis may be caused by trauma to the levator muscle, insult to the superior cervical sympathetic ganglion or damage to the oculomotor nerve. Such damage could be a sign or symptom of an underlying condition such as diabetes mellitus, a brain tumour, a Pancoast tumour affecting the apex of the lung, or diseases which cause weakness in muscles or nerve damage, such as myasthenia gravis or oculopharyngeal muscular dystrophy. (6) Exposure to toxins in some snake venoms, such as that of the black mamba, may also result in ptosis. (6) Acquired ptosis may result from chronic inflammation or following intraocular surgery. (6) Wearing contact lenses for long periods of time can lead to the development of ptosis in some patients. (6) Other causes of ptosis include eyelid neoplasms or neurofibromas. (5)
According to Coles, (1) ptosis (bilateral or unilateral) may be: congenital when it is present at birth; and acquired when it develops after birth. Acquired ptosis may be: age-related; a result of oculomotor (third nerve) palsy, due to intracranial tumour; or a result of trauma, as in intraocular surgery, for example, after cataract surgery. Pseudoptosis can be simulated in a small globe due to injury or inflammation resulting in an abnormal shape, as in pthisis bulbi or due to ipsilateral hypotropia.
Why should it be treated?
DeSouza et al described an infant having congenital bilateral ptosis and captured her remarkable ability to lift the eyelid with the hand in order to see (see Figure 2) (7) Patients mostly complain of the cosmetic effect of drooping of the upper lid, and in more marked cases there may be interference with vision. In congenital cases this interference may be sufficient to cause amblyopia; therefore, ptosis, needs to be treated not only to improve cosmesis and vision but also to safeguard against the affected eye becoming amblyopic.
There are different ways to approach ptosis surgically, depending on the aetiology, and detail on these techniques is beyond the scope of this article. Lyle and Cross suggest that in cases of congenital origin, if the deformity is not of gross degree and there is no interference with vision which might lead to amblyopia, surgical treatment may be postponed until the child reaches the age of four or five years; otherwise surgical intervention may be indicated even as early as six months of age. (8) When the condition is acquired, treatment depends upon the cause, which must be investigated. In cases of paralysis of the oculomotor nerve, the drooping eyelid may serve the useful function of preventing double vision, and if there is useful vision in the eye, the possibility of correcting diplopia should be considered before the eyelid is returned to its normal position. Following surgery, it is important that the eye can still be closed. Figure 3 depicts optimal surgical correction.
Lee makes the following observation on surgical intervention: in congenital ptosis, the levator muscle is infiltrated with fat and fibrosis and is basically non-functional, so the eyelid is most commonly suspended from the adjacent frontalis muscle using a sling. In acquired ptosis, which has levator dehiscence, when the muscle is functioning properly, the two most common procedures are conjunctival-Muller muscle resection (CMMR) and levator aponeurosis repair (LA).9 On clinical evaluation, it is important to measure palpebral fissure height, levator function and marginal reflex distance. If the patient has good levator function, a CMMR or LA may be appropriate. The patient is often assessed in clinic using one or two drops of phenylephrine to check whether Miiller's muscle responds and the lid elevates. If the lid responds, the patient is likely to be a good candidate for a CMMR. If the lid does not respond, some surgeons will proceed with a CMMR regardless, but many will resort to a LA. Advantages of CMMR include the fact that the procedure is faster and is generally associated with less swelling and postoperative lagophthalmos. The disadvantage is that it may have to be done under monitored anaesthesia care since the eyelid has to be double everted and the correction of ptosis is modest. LA can be done under local anaesthesia but generally takes more time and is associated with more swelling.
Management with spectacles and contact lenses
In cases where surgery is not preferred or indicated, for example, in cases of myasthenia gravis, muscular dystrophy, poor Bell's phenomenon, or excessive dry eye, a prosthetic device such as a ptosis prop (crutch) fixed to the back of the spectacle frame is often of great value.
Until recently, in India, a small semi-circular piece cut from the periphery of an old gramophone record used to be glued to the inside of the upper portion of a plastic spectacle frame to lift the drooping upper lid. But, the device was not cosmetically appealing and was also uncomfortable.
Dr Moss reports on the method of relieving ptosis with the use of a scleral contact lens. Either the superior flange of the shell is built up by increasing the mass, which elevates the upper lid and improves ptosis.10 Alternatively, a shelf is placed across the upper section of the scleral lens to support the upper lid; however, this approach may well result in lack of blinking. Parker's observation about the use of a standard scleral contact lens is interesting, thought-provoking and straight-forward: "I do believe that a standard scleral contact lens will have a positive effect on this condition. I do not believe it has to be made with much of a custom front surface. A normal scleral lens of any type will usually have a positive effect of lifting the lid. The comment made by Dr Moss was speculative on what may be possible. But building a lens with a shelf and / of holding ridge will not be comfortable and will create a deficiency in blinking, creating its own issues. I suggest you could prescribe a standard, the larger the better, scleral lens with the needed Rx on these types of patients and achieve a positive cosmetic effect." (11)
Moss also details the making of an improved prop by utilising orthodontic round steel wire, and fixing it to the bridge of a modern plastic spectacle frame to improve cosmesis and give greater movement to the upper lid. (10) However, the procedure is cumbersome and needs precision.
Let's now consider a comparatively simpler method of making a ptosis spectacle by fixing a support to a plastic frame that is made of nylon thread which is sturdy and comfortable. A hole, slightly smaller than the thickness (diameter) of the support, is drilled at the bridge on the front side of the frame. One end of the support is thinned with a surgical knife or razor blade and the cord (nylon thread) pushed on the inside of the frame. Another hole is drilled at the temple on the inside of the frame out of which the free end of the cord is pulled through. The nasal end of the cord is pressed with a plier so as to flatten it and prevent it from coming out of the hole at the bridge. Easy adjustment can be made by pulling the support from the front at the temporal end with a pair of pliers until the required depth is achieved (see Figure 4). The support will then fit the contours of the upper lid. Care needs to be taken not to overcorrect the drooping upper lid elevation, so as to avoid secondary mechanical effects on ocular surface/adnexa due to the support. (12)
The prosthetic device can correct almost all types of ptosis. The cosmetic improvement is good, the positive impact on the patient is rewarding. There may well be the possibility of prolonged functional improvement in the condition because of mechanical stimulation. (13)
Ptosis is the prerogative of the oculoplastic surgeon. But there are cases where either the doctor decides against surgery or the patient simply refuses to be operated upon. Ptosis, then, comes into the domain of the primary eyecare practitioner who should be able to provide a judiciously fitting pair of ptosis spectacles to improve the cosmetic and visual outcome for these patients.
Exam questions and references
Under the enhanced CET rules of the GOC, MCQs for this exam appear online at www.optometry.co.uk. Please complete online by midnight on 27 December 2017. You will be unable to submit exams after this date. Please note that when taking an exam, the MCQs may require practitioners to apply additional knowledge that has not been covered in the related CET article. CET points will be uploaded to the GOC within 10 working days. You will then need to log into your CET portfolio by clicking on 'MyGOC' on the GOC website (www.optical. org) to confirm your points. Visit www.optometry.co.uk, and click on the 'Related CET article' title to view the article and accompanying 'references' in full.
Couse code: C-57529 Deadline: 27 December 2017
* Be able to outline options for managing ptosis to patients (Group 1.2.4)
* Understand how to fit a ptosis prop (Group 4.1.5)
* Understand the aetiology, presentation and classification of ptosis (Group 6.1.4)
* Be able to outline options for managing ptosis to patients (Group 1.2.4)
* Understand how to fit a ptosis prop (Group 4.2.2)
* Be aware of the aetiology, presentation and classification of ptosis (Group 6.1.4) Dr Narendra Kumar BAMS, DROpt, PGCR
Dr Narendra Kumar served as a refractionist at Sir Ganga Ram hospital for 30 years and now works at an ophthalmological clinic where he looks after refraction and contact lens cases. He is the chairman of the charitable trust Eye Care India, the author of Ophthalmic Dispensing Optics, and editor of the Indian-based journal Optometry Today.
Caption: Figure 1 Patient with ptosis. Image courtesy of Ophthacare Eye Centre '
Caption: Figure 2 Photograph capturing an infant with congenital bilateral ptosis due to Moebius syndrome. Taken at the age of seven months, the photograph illustrates her remarkable ability to lift the eyelid in order to see, a skill that was repeatedly demonstrated from six months of age. Image courtesy of R De Souza and DA Spencer, Coventry Health Authority
Caption: Figure 3 Ptosis: preoperative (A) and postoperative (B). Image courtesy of Dr Maneesh Kumar
Caption: Figure 4 Frame front fitted with nylon cord support. Image courtesy of Optometry Today, India
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|Date:||Dec 1, 2017|
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