Although there are numerous classifications for ptosis; such as congenital versus acquired, neurogenic, myogenic, traumatic, and mechanical ³, none of those classifications provides a complete approach to the ptosis patient, nor does any of them guide the clinician to the development of a system for adequate repair. Classifying ptosis as minimal = 0.5–1.5 mm, moderate = 2.0–3 mm, or severe >3 mm based on the amount of ptosis provides a practical framework for a logical system of repair when this system is used in conjunction with the amount of levator excursion. This last measurement is an indirect measurement of the viability of the levator palpebrae superioris and an excellent predictor of the surgical outcome. Using this matrix the appropriate choice of surgical strategy can then be applied to each of these three scenarios.

Basic considerations

The involuntary upward excursion of the eye upon attempted lid closure is denominated Bell’s phenomenon; certain surgeons feel that the presence or absence of Bell’s phenomenon is of significant importance in ptosis surgery. In most circumstances, its absence is considered a contraindication to ptosis surgery and/or if not at least an important warning sign. While the anterior statement holds true for adults, due to the risk of developing postoperative exposure keratopathy and subsequent corneal perforation after surgery in the absence of Bell’s phenomenon, it is not a contraindication to surgery in patients with congenital ptosis.

In general it is prudent to exercise extreme caution in patients when performing surgery in those with processes like thyroid myopathy, progressive external ophthalmoplegia, or dystrophies in which a poor Bell phenomenon is observed. Lagophthalmos and corneal exposure, along with decreased eye movements during REM sleep, and poor orbicularis muscle function may exist and lead to corneal perforation. Loss of the blink reflex or compromised corneal sensitivity, paralysis of the orbicularis, and significant keratitis sicca are definite contraindications to surgery.

Goals of surgery

Blepharoptosis is one of the most commonly encountered oculoplastic problems, but also at the same time one of the most challenging problems from the surgical standpoint. The goal of ptosis surgery is to obtain, as much as possible, an anatomic and physiologic result by elevating the lid or lids to an adequate position and, if necessary, to clear the pupil from the obstruction created by the eyelid’s downward displacement. Additionally, special attention must be given not to disrupt the natural contour and symmetry of the eyelids.

Thorough understanding of these goals and of the limitations of ptosis surgery is important, for both the surgeon and the patient. Also patients and their families must be fully aware of these goals and limitation before surgery is performed. It is advisable that the expectations and anticipated surgical results are discussed carefully with the patient and/or the parents preoperatively and documented in writing as part of the informed consent process. This proves particularly true in congenital ptosis, since in this instance factors inherent to the anatomic defect of the defective levator palpebrae superioris muscle impose limitations on the surgical results. Surgery cannot restore the function to a compromised muscle with an already abnormal or absent function preoperatively. In congenital ptosis with a frontalis suspension procedure or a maximal levator resection the lid level can be changed, but dynamic results will not be obtained postoperatively, and surgery may result in significant lid lag and lagophthalmos that is still more obvious on downgaze. The best result that can be hoped for in congenital ptosis surgery is a normal lid level, contour, and symmetry when the eyes are in the primary position, with adequate clearance of the visual axis.

Indications for surgery

In patients with acquired blepharoptosis, surgery is often recommended when the patient’s activities of daily life are compromised by the occlusion of the visual axis caused by the droopy eyelid, a significant superior visual field is reported or perceived by the patient, or extreme fatigability of the eyelid and occlusion of the pupil occur while in downgaze, affecting mainly activities like reading amongst others. Vision may be affected in patients regardless of the amount of ptosis. During the preoperative evaluation, visual or asthenopic symptoms secondary to the ptosis might be elicited; when these are present, they usually indicate the need for surgery. Third-party payers now require documentation of symptoms, field defects, and by clinical photographs routinely.

In most instances, the primary reason prompting the parents to seek for help in correcting congenital ptosis is cosmetic. It is generally agreed that disfiguring congenital ptosis should be repaired by age 5 years or before the child begins regular school to avoid psychosocial issues during the child’s socialization phase, but setting an arbitrary age for surgery serves no purpose. Earlier intervention is performed in children with severe bilateral ptosis that interferes with the child’s ability to learn how to walk, due to the extreme head position that they adopt with the chin-up position. Another exception arguing for early intervention is made in patients with unilateral or bilateral severe congenital ptosis where the normal visual development is compromised by total occlusion of the visual axis. In some of these instances surgical intervention may be even indicated shortly after birth. Disruption or loss of compensatory mechanisms of binocular fusion such as chin-up head position is a sign of development of amblyopia, which must be treated urgently with surgical correction of the ptosis and appropriate amblyopia management, with occlusion therapy and glasses when necessary.

Preoperative assessment

In the evaluation of the ptosis patient, history taking is one of the most important elements. If the ptosis is congenital, the physician should question the patient or family about the absence or presence of jaw winking and family history of ptosis. With acquired ptosis, the timing of onset is of extreme importance (acute vs. progressive or chronic). A history of fatigability or variable ptosis with exercise or through the day should warrant a work-up for myasthenia gravis, especially if there is noticeable improvement with rest. Associated neurologic symptoms, if any, should also be investigated. History of orbital or ocular trauma, previous ocular histories of inflammatory disorders, or contact lens wear may also be germane. The ocular exam should be complete. In addition to documenting the patient’s visual acuity and ocular motility, the importance of the pupillary function exam should not be underestimated. Anisocoria suggestive of Horner syndrome should be fully evaluated. The presence or absence of Bell’s phenomenon should be documented, as well as quantitative and qualitative properties of the tear film both by Schirmer’s testing and by study of tear break-up time. Slit-lamp examination should be used to assess the integrity of the cornea and the conjunctiva and to detect any inflammatory disease or subclinical pathology.

Children with ptosis should have full-dilated exams, retinoscopy, and assessment of ocular motility and sensory function with either fixation preference, the 10Δ base-down prism test, or a formal stereopsis test to rule out amblyopia. Careful motility examination in pediatric patients may uncover a double elevator palsy associated with the ptosis or partial third cranial nerve involvement causing the ptosis.

Assessment of ptosis and documentation

Ptosis is documented by the margin to reflex distance 1 (MRD₁)⁴, which is the distance from the central pupillary light reflex to the upper eyelid margin, measured in millimeters. It is important to document the amount of ptosis to the nearest 0.5 mm, if possible. The margin to reflex distance 2 (MRD₂) is the distance from the central pupillary light reflex to the lower eyelid margin. The MRD₁ plus the MRD₂ should equal the palpebral fissure.

The levator excursion test is the best clinical means for assessing levator function. The levator excursion is documented in millimeters, measuring the distance from extreme upgaze to downgaze with the brow immobilized by the examiner’s thumb to eliminate any contribution of the brow to lid elevation. A millimeter ruler is used vertically in the pupillary axis to assess the full excursion. Levator excursion of 10 mm or greater is considered good function; 5–9 mm of excursion is fair function; and 4 mm or less is poor function.

Patients with minimal ptosis (2 mm or less) should have a phenylephrine test performed in the involved eye or eyes after appropriate ptosis measurements have been documented. Either 2.5% or 10% phenylephrine is instilled in the affected eye or eyes. We prefer to use 2.5% phenylephrine. Usually two drops are instilled and the patient is re-examined 5 minutes later. The MRD₁ is rechecked in the affected and unaffected eyes (Fig. 48.2). A rise in the MRD₁ of 1.5 mm or greater is considered a positive phenylephrine test. This indicates that Müller’s muscle is viable, and the Müller’s muscle conjunctival resection procedure can be performed, also giving the patient a reasonable prediction of the desired result.