Joseph L. Demer is a strabismologist at Jules Stein Eye Institute who originally did his Fellowship in Texas under the guidance of Gunter K. von Noorden in the late 1980s. In the early 1970s he was a broadcast engineer at KVOA-TV in Tucson while working his way through a degree in electrical engineering at the University of Arizona. Turning his attention toward humans, he entered a joint M.D., Ph.D. program at Johns Hopkins, earning his degree in biomedical engineering in 1981. Since that time he has been occupied with the biomechanics of extraocular muscles, and his early work on the involvement of EOM pulley systems in strabismus is reviewed in his chapter in Duane’s Clinical Ophthalmology.
In February 2008, Demer wrote an op-ed published in JAAPOS that advised his fellow surgeons to have more respect for the role of connective tissue in strabismus. In it, he noted that muscle orbital layers were recognized to insert in pulley connective tissues, and that degeneration of these connective tissues occurs with aging and can be correlated to limitation in vertical duction and sagging of horizontal rectus pulleys. In the following year Demer co-authored a paper on “Heavy Eye” Syndrome, an acquired strabismus of aging. To differentiate this from acquired strabismus due to biomechanical forces in high myopia, in which the angle of divergence insufficiency esotropia was larger, Demer referred to this entity as “Sagging Eye” Syndrome.
The case of a sagging 77 year-old female, representative of this newly identified clinical entity, was presented in the University of Iowa Health Care Eye Rounds a few years ago and is instructive. It begins: “A 77-year-old female presented with a complaint of intermittent, binocular, horizontal diplopia that had been present for the last six months. The diplopia was only present at distance and she denied double vision with near tasks.” The patient had a 4 prism diopter esotropia in primary gaze that increased on both left and right gazes, and a very small left hypertropia measuring less than 2 prism diopters in all gaze directions. She was given a trial of Fresnel prism for symptomatic control of the diplopia. Follow up at 4 and 10 months showed stable strabismus measurements and no complaints of diplopia. A prescription for ground-in prism was given and she was scheduled for annual follow-up.
Sagging Eye Syndrome (SES) is nicely summarized by the American Academy of Ophthalmology’s EyeWiki, and differentiated into Age Related Distance Esotropia (ARDE) in which there is distance esotropia with no vertical versus Cyclovertical Strabismus (CVS) in which there is cylovertical diplopia, although the conditions may co-occur.
The AAO EyeWiki page makes it clear that prism therapy is the treatment of choice for SES, particularly when the angle is small (as it usually is) and the patient is not going to be independent of spectacles anyway. It also notes that because the patient typically has good fusional reserves, even though the prism is required only for distance, it is accept well by the patient at all distances. Parenthetically, this has been my experience in prescribing small amounts of prism for patients with convergence insufficiency or uncompensated vertical drift – even though the prism may be require primarily at one distance or angle, it is often accepted well at all distances and angles of gaze. There are also select cases where vision therapy can complement the acceptance of prism and stabilize the binocular profile.
In a new article on the subject in the American Journal of Ophthalmology, Demer and colleagues report on the Prevalence of Sagging Eye Syndrome in Adults with Binocular Diplopia. The medical records of 945 patients over 40 years of age presenting with acquired diplopia were reviewed. The most common cause of diplopia in this population was SES (31.4%). They report that 35% of their patients (104) with SES had ARDE, and 65% (193) had CVS, with combined hyper/eso in 28.2% and hyper alone in 36.7%. The average age of patients with SES was 71.2 years, with a preponderance of females. Female sex hormones such as progesterone and esotrogen are known to be important in maintaining collagen content by preventing the collagen degradation in women. Since levels of those hormones decrease after menopause and the orbital pulley system is composed of collagen, elastin, and smooth muscle, it would not be surprising for involutional changes in orbital connective tissues to be more common in females than males.
To summarize, patients with SES typically present with some or all of the following:
*Deep superior sulcus
*High upper lid crease
*Small angle hypotropia
*Small angle excyclotorsion
*Small angle esotropia (greater for distance than near)
*Mild limitation in supraduction
*Normal horizontal saccadic velocity
Once you know about this condition, you will start to recognize it more often among geriatric patients. In contrast with acquired divergence insufficiency under the age of 40 which is suspect for tumor, vascular, or neurologic disease, diagnosis of SES can spare the patient expensive and low yield neurological testing and focus on alleviating symptoms and improving quality of life.