Purpose
Sagging eye syndrome (SES), horizontal and/or vertical strabismus caused by orbital connective tissue degeneration, was first defined 10 years ago. This study investigated SES and other causes of acquired binocular diplopia in adults presenting to a single institution since the description of SES.
Design
Retrospective observational case series.
Methods
Medical records were reviewed of all new patients over the age of 40 who presented to the Stein Eye Institute with binocular diplopia between January 2015 and December 2018. Clinical causes of diplopia were tabulated in patients grouped by age and sex. In patients with SES, we tabulated binocular alignment, types of treatment, and surgical outcomes.
Results
There were 945 patients of mean age 66.5 years, of whom 514 (54.4%) were female. The most common cause of diplopia was SES (31.4%). The 297 patients with SES were older at 71.2 years ( P < 0.0001) and more predominantly female at 59.9% than other patients (52.0%; P = 0.023). The relative proportion of SES patients among all diplopic patients increased with age from 4.7% under age 50 years to 60.9% over the age of 90. Age-related distance esotropia was present in 35% and cyclovertical strabismus in 65% of cases of SES. Strabismus surgery was performed in 50% of cases of SES. Mean esotropia at distance decreased from 6.9 ± 0.7Δ preoperatively to 0.3 ± 0.3Δ postoperatively. Preoperative hypertropia decreased from 3.0 ± 0.3Δ to 0.7 ± 0.2Δ postoperatively. Surgery resolved diplopia in all cases.
Conclusions
It is important to recognize that SES is a very common cause of adult binocular diplopia.
Aging is a progressive risk factor for strabismus, with incidence increasing with age. Reports of the causes of acquired diplopia in adults have emphasized cranial nerve palsies, with most studies reporting trochlear or abducens palsy as the most common cause of diplopia. Previous reports indicated that the incidence of cranial neuropathies increases with age. , However, elderly diplopic patients are often encountered in whom cranial neuropathies are implausible or have been ruled out.
Aging is also associated with a decrease in the range of ocular movements, particularly supraduction. This phenomenon is caused by inferior displacement of the horizontal rectus extraocular muscle pulleys in the elderly as the pulley suspensions degenerate. A decade ago, Rutar and Demer introduced the sagging eye syndrome (SES) as a form of strabismus caused by degeneration of the rectus pulley suspensions. Magnetic resonance (MR) imaging in SES demonstrates thinning of the lateral rectus-superior rectus band ligament, permitting inferior displacement of the lateral rectus pulley. When inferior displacements of lateral rectus muscle pulleys are similar in both eyes, SES presents as distance esotropia more than near; if inferior displacements differ in the 2 eyes, the presentation may include cyclovertical strabismus. Clinical diagnosis of SES is based on motility patterns and the presence of age-related adnexal changes such as superior sulcus deformity, aponeurotic ptosis, and high lid crease. Since its initial description 10 years ago, SES has been increasingly recognized as a cause of acquired diplopia in adults.
Kawai and associates reported the causes of acquired diplopia in Japanese adults 60 years old or older, based on a review of 236 cases imaged with MR imaging. They considered 3 types of orbital pulley disorders: SES, heavy eye syndrome, , and highly myopic strabismus. , Kawai and associates reported that the most frequent cause of diplopia in these older Japanese adults was orbital pulley disorder, causing 24.2% of cases. Except for Kawai and associates, all other clinical studies of diplopia causes were performed before recognition of the existence of SES. Therefore, the current study investigated the prevalence of SES in older adults who complained of acquired binocular diplopia in a population in the United States.
Methods
Subjects
The medical records of new patients 40 years old or older who presented to the Pediatric Ophthalmology and Strabismus Division of the Stein Eye Institute between January 2015 and December 2018 with the complaint of acquired binocular diplopia caused by strabismus were reviewed
This study was approved by the Institutional Review Board of the David Geffen School of Medicine, University of California, Los Angeles, and followed the tenets of the Declaration of Helsinki.
Diagnostic criteria for Sagging Eye Syndrome
Two types of strabismus due to SES were included: age-related distance esotropia (ARDE), with deviation greater at distance than near, and small-angle cyclovertical strabismus with or without horizontal strabismus (CVS). ARDE was defined as symptomatic esotropia at distance, with orthophoria or asymptomatic esophoria of 10Δ or less at 33 cm near viewing distance. CVS was defined as symptomatic vertical strabismus meeting the following criteria: 1) the hypotropic eye was more excyclorotated than the hypertropic eye; 2) results of versions and/or Hess screen testing were inconsistent with the classical superior oblique palsy (SOP) pattern of significant underdepression in adduction and/or overelevation in adduction; 3) differences in hypertropia with head tilting to the right and left shoulder 6Δ or less; and 4) absence of superior oblique muscle atrophy on MR imaging when available. Normal saccades were required, as were age-related external ocular adnexa findings of SES such as superior sulcus deformity, aponeurotic ptosis, or high lid crease. Other causes of strabismus were excluded, such as thyroid ophthalmopathy, cranial nerve palsies, myasthenia gravis, childhood-onset strabismus, orbital trauma, and any types of restrictive strabismus, for example, resulting from scleral buckles, brachytherapy plaques, or glaucoma drainage devices.
Main Outcome Measurements
Clinical factors were recorded, including age, sex, and cause of diplopia in all patients. We divided patients into those with SES versus those having other causes of diplopia (others). Intergroup comparisons were performed for age and sex. In patients with SES, binocular alignment was recorded at distance (5 m) and near (33 cm) by prism and alternate cover testing in primary position, as well as types of treatment administered. Patients with SES were subdivided into a group with ARDE versus a group with CVS, based on binocular alignment at first visit. We evaluated the surgical outcomes of those who underwent strabismus surgery.
Statistical Analyses
Statistical analyses were performed using Prism version 7 software (GraphPad Software, Inc., La Jolla, California). The Student t -test was used to compare age distributions, and the chi-square test to compare gender differences. Paired t -testing was used to compare pre- and postoperative strabismus angles. The 0.05 level was considered statistically significant.
Results
A total of 945 patients over age 40 years with newly presenting with diplopia caused by strabismus were identified. Mean age at the initial visit was 66.5 ± 11.8 years. Most subjects were between 60 and 80 years old ( Figure 1 ). There were 514 females (54.4%) and 431 males (45.6%).
Causes of Diplopia
The most common cause of diplopia was SES, identified in 297 patients (31.4%). The second most common cause was trochlear palsy (10.3%) followed by thyroid eye disease (8.3%), mechanical strabismus due to implantation of devices such as scleral buckles, brachytherapy plaques, glaucoma drainage devices (7.2%), abducens palsy (6.9%), convergence insufficiency exotropia (5.1%), orbital fracture (3.3%), intermittent exotropia (2.5%), myasthenia gravis (2.1%), oculomotor palsy (1.9%), decompensated esophoria (1.9%), strabismus operated in childhood (1.7%), heavy eye syndrome (1.5%), sensory exotropia (1.4%), internuclear ophthalmoplegia (1.3%), decompensated exotropia (1.1%), childhood strabismus never operated (1.0%), skew deviation (1.0%), consecutive exotropia (1.0%), consecutive hypertropia (0.8%), consecutive esotropia (0.8%), Duane syndrome (0.8%), nystagmus (0.8%), and miscellaneous others (4.4%) ( Figure 2 ).
Age
The average age of patients with SES was 71.2 ± 9.9 years, significantly older than the group with other causes of strabismus at 64.4 ± 11.9 years (standard deviation, P < 0.0001) ( Figure 3 A). The relative proportion of SES among all patients increased with age ( Figure 3 B). In patients aged 40–49 years, SES caused 4.7% of all diplopia, increasing to 19.3% in ages 50–59 years, 31.4% in ages 60–69 years, 41.8% in ages 70–79 years, 40.0% in ages 80–89 years, and 60.9% over age 90 years.
Sex
There were 178 females (59.9%) and 119 males (40.1%) in the SES group, representing a significantly greater preponderance of females than the 337 females (52.0%) and 311 males (48.0%) in the group with other causes of diplopia ( P = 0.023).
Strabismus Types in SES
There were 104 patients (35.0%) with ARDE. These patients had mean (± SEM) estropia of 9.1 ± 0.6Δ at distance but less than 1.6 ± 0.5Δ at near ( Figure 4 ). There were 193 patients (65.0%) with CVS. These patients had mean hypertropia of 3.9 ± 0.2 and mean estropia of 3.8 ± 0.6Δ at distance, but there was no significant horizontal strabismus at near ( Figure 4 ). There was combined hypertropia and esotropia in 84 patients (28.2%), and 109 patients (36.7%) had hypertropia alone.
