Etiology
- Rarefaction of levator aponeurosis or disinsertion from tarsus
- The aponeurosis has two sites of attachment to the tarsus, superficially along the anterior tarsal surface and deeper fibers that attach along the superior aspect of the tarsus (Marcet, Ophthalmology, 2013).
- With detachment there can be loss of pulling effect of muscle
- With rarefaction the measured levator excursion may be normal but the resting position of the lid margin will be lower.
- Medial attachments of levator are less robust than lateral attachments, and medial ptosis can be more marked than lateral (Kakizaki, OPRS, 2004).
- Increased reactivity of marker for oxidative stress in the levator tissue in cases of aponeurotic ptosis (Kase, OPRS, 2014)
- Decreased carotenoid content in the preaponeurotic fat of ptosis patients, suggesting a loss of protection against oxidative stress (Ahmadi, OPRS, 2005)
- Histopathologically, marked by age-related changes including loss of collagen and secondary fatty infiltrate (Dortzbach, Archives of Ophthalmology, 1980)
- Acquired ptosis after eye surgery may be due to orbicularis contraction against speculum, bridle sutures, anesthetic injections (Linberg, 1986).
- When ptosis was first seen after refractive surgery the candidate causes seemed to reduced to the speculum, because other risk factors had been eliminated.
- Eye drops are another potential cause.
Epidemiology
- 5% of population after 50 years of age (Sridharan, Age Ageing, 1995)
- Postoperative
- Estimates of incidence after cataract surgery range from 4% to 12% (Altieri, Ophthalmologica, 2005; Mehat, Orbit, 2012).
- Rate appears to be much higher with extracapsular cataract extraction than with phacoemulsification (Puvanachandra, Orbit, 2010).
- Rate is comparable after combined trabeculectomy with phacoemulsification (12.7%) versus trabeculectomy alone (10.7%).
- No difference between fornix- or limbus-based flaps
- No difference between primary surgery and revision (Song, Korean Journal of Ophthalmology, 1996)
- Contact lens use
- Much more common with hard contact lenses, but can be associated with soft contact lenses (Bleyen, Canadian Journal of Ophthalmology, 2011).
- 20-time increased risk of ptosis among hard contact lens wearers (Kitazawa, EPlasty, 2013)
- 10 of 46 patients who had been wearing hard contact lenses for at least 10 years had ptosis compared with 1 of 50 matched controls (van den Bosch, 1992).
- Identifiable factor in 47% of young-to-middle age acquired ptosis patients (Kersten, Ophthalmology, 1995)
- Allergy and eyelid rubbing (Fujiwara, Annals of Plastic Surgery, 2001)
- Long-standing edema
- Thyroid eye disease (Naseem, Eye, 2009)
Clinical features
- The hallmark of aponeurotic ptosis is preservation of levator function
- There are reports of subtle, but statistically significant, decrease in levator function that correlates with marginal reflex distance, as ptosis progresses (Pereira, American Journal of Ophthalmology, 2008).
- Suboptimal levator function should encourage a consideration of myogenic or neurogenic ptosis.
- Ask about prior trauma, contact lens wear, ocular surgery, general medical conditions
- Aponeurotic ptosis is defined as lid height reduced by 2 mm or more with 8 mm or more of lid elevation from downward to upward gaze (Jones, 1975).
- Such cases have adequate striated muscle and normal neurologic stimulus
- Elevated eyelid crease
- No lid lag on downgaze
- Thin eyelid
- Palpebral fissure asymmetry is related to horizontal gaze, widening in the abducting eye. Prevalence of asymmetry in primary gaze defined as 1 mm or greater was 5.7% (Lam, 1995).
Testing
- Aponeurotic ptosis is a clinical diagnosis which requires supportive ancillary testing
- Ask about prior trauma, surgery, general medical conditions.
- Assess visual acuity and status of the eyes.
- Check for fatigability and extraocular motility deficits.
- In unilateral cases, check for presence of Hering's phenomenon (Figures 1 and 2).
Figure 1. Bilateral ptosis worse on left with with marginal reflex distance 1 mm on the right. Image courtesy Scott M. Goldstein, MD.
Figure 2. Ptosis on the right is worse with manual lid elevation on the left due to Hering's law. Image courtesy Scott M. Goldstein, MD.
- Assess marginal reflex distance, lagophthalmos, levator function, crease height.
- Photographs for documentation (Figure 3)
- Consider provocative testing with phenylephrine to assess for Muller muscle function, where appropriate.
- The four activities identified in Quality of Life assessment that improve after unilateral and bilateral surgery are the ability to perform fine manual work, reaching for objects above eye level, watching television and reading (Battu, 1996).
Figure 3. Ptosis. Image courtesy Scott M. Goldstein, MD.
- Visual field testing
- Quantifies degree of visual field loss and reversibility
- For some local carriers, the Center for Medicaid and Medicare Services (CMS) has defined a 30% loss of superior visual field as the minimum requirement for medically necessary ptosis repair.
- Typically, height of superior visual field at 90‑degree meridian is used to define superior visual field.
- Decrease in field correlates with degree of ptosis (Meyer, Archives of Ophthalmology, 1989).
- Both manual kinetic and automated static visual field tests reliably document degree of impairment, but manual kinetic testing is faster and more sensitive (Rienmann, Archives of Ophthalmology, 2000).
- Assess ocular surface by slit-lamp biomicroscopy
- Schirmer testing
- Aponeurotic ptosis can be repaired in the context of dry eye condition that is being effectively controlled.
- Widening the fissure can increase evaporation of the tear film and can worsen dry-eye syndrome (Mehta, American Journal of Ophthalmology, 2008).
- Tear volume may decrease after ptosis repair (Watanabe, Cornea, 2014).