Sagging Eye Syndrome (SES)

Historical Background

Early Recognition: ARDET (2009)

The journey to understanding SES began in 2009 with the description of ARDET (Age-Related Distance EsoTropia). This condition was characterized as an acquired form of strabismus affecting elderly patients, presenting with:

• Greater esotropia at distance fixation without abnormal ductions or versions

• Balanced fusion amplitudes or slight divergence insufficiency

• Orthophoria at near vision

The Breakthrough: Joseph L. Demer's Research (2013)

The syndrome was formally described in 2013 by the team of Joseph L. Demer, thanks to advances in MRI technology and the study of pulley system evolution.

Anatomy and Pathophysiology

Normal Orbital Anatomy

The eye is covered by Tenon's capsule, a thin fibro-elastic membrane that:

• Begins at the limbal sclera

• Surrounds the eyeball and optic nerve

• Forms a cavity in which the globe moves

• Separates the eye from orbital fat

• Extends muscle sheaths onto the scleral surface

At the posterior pole of the eye, connective tissue bands called "pulleys" (from the Greek word for "pivot") connect to the rectus muscles and are located anterior to the orbital wall. These pulley bands serve crucial functions:

• Stabilizing muscle trajectories

• Playing an important role in ocular movements

• Determining the force directions of extraocular muscles

Pathological Changes in SES

MRI studies have revealed the progressive changes that occur in SES:

1. Early Stage (ARDET): Marked elongation of the LR-SR band (lateral rectus-superior rectus band) with sagging of the lateral rectus muscle

   

2. Advanced Stage (SES): Complete rupture of the LR-SR band with significant displacement of the lateral rectus muscle downward and inward

3. Associated Changes:

   • Elongation and curvature of superior and inferior rectus muscles

   • Aponeurotic ptosis with levator muscle detachment

   • Optic nerve coiling

   • Superior palpebral sulcus defects

MRI Findings

Advanced imaging techniques allow visualization of:

• The LR-SR band integrity

• Muscle displacement patterns

• Angle measurements showing displacement (normal vs. >101° in SES)

• Bilateral involvement patterns

Clinical Characteristics

Primary Signs

SES presents with distinctive clinical features that vary depending on whether the condition is unilateral or bilateral:

Asymmetric Involvement:

• Minimal distance esotropia

• Hypotropia and excyclotorsion of the affected eye

Symmetric Involvement:

• Minimal distance esotropia without vertical component

Associated Oculo-Palpebral Changes

Due to the aging process, SES often presents alongside:

• Ptosis (drooping eyelids)

• Dermatochalasis (excess eyelid skin)

• Lipoptosis (fat pad prolapse)

• Superior tarsal sulcus hollowing

Triggering Factors

SES symptoms often become apparent after ocular surgeries that improve vision:

• Cataract surgery: Previously, cataracts may mask visual disturbance and diplopia. Once removed, diplopia becomes evident, sometimes leading to wrongful blame of the surgeon or anesthesia

• Cosmetic eyelid procedures: Dermatochalasis correction, lipoptosis surgery

• Botulinum toxin injections

Clinical Examination and Orthoptic Assessment

Functional Symptoms

• Poorly defined visual disturbance at distance

• Distance diplopia

• Generally asymptomatic at near vision

Motility Assessment

• Versions: Minimal limitation of abduction in one or both eyes, or essentially normal

• Ductions: Generally balanced

Deviation Measurements

• Distance: Esotropia

• Near: Orthophoria to esophoria

• No torticollis or abnormal head posture

• No version incomitance or fixation-dependent incomitance

Binocular Vision Studies

Comprehensive assessment includes:

• Stereotests

• Worth 4-dot test

• Vergence testing

• Synoptophore examination for correspondence

Diplopia Analysis

• Homonymous diplopia at distance (symmetric involvement)

• Associated vertical diplopia (hypotropia) and excyclotorsion in the more affected eye (asymmetric involvement)

Coordimetry

Confirms deviation patterns on diagrams, providing valuable evolutionary and medical documentation.

Case Studies

Case 1: Mrs. Monique B. (80 years old)

• Presentation: Homonymous diplopia in all gaze directions since late 2010

• History: Bilateral cataract surgery late 2016-early 2017

• Referral: May 2017 for worsened diplopia

• Treatment: 30Δ base-out prism trial, surgical intervention planned

• Outcome: Demonstrates typical post-cataract surgery revelation of SES

Case 2: Mrs. D.F. (82 years old)

• History: Bilateral cataract surgery September-October 2016

• Progressive management: Escalating prism correction from 6Δ to 8Δ base-out

• Findings: 3° excyclotorsion left eye, second-degree binocular vision

• Management: Combined incorporated and press-on prisms

Treatment Options

Non-Surgical Management

1. Prism Correction:

   • Press-on prisms for trial periods

   • Incorporated prisms in spectacle lenses

   • Progressive increase often necessary

2. Monitoring:

   • Regular orthoptic surveillance

   • Documentation of progression

   • Generally progressive condition

3. No Role for Orthoptic Exercises:

   • Traditional orthoptic rehabilitation is not effective

   • Mechanical nature of the problem prevents muscle training success

Surgical Management

When prism correction becomes inadequate:

1. Bilateral Medial Rectus Recession:

   • Indicated for symmetric cases

   • Addresses the convergent strabismus

2. Kaufmann and Krzizok Technique:

   • Lateral rectus elevation procedure

   • Addresses the mechanical displacement

   • Restores more normal muscle geometry

Differential Diagnosis

ARDET (Age-Related Distance EsoTropia)

• Very similar to SES

• Represents earlier stage with band elongation but no rupture

• Minimal distance esotropia related to Tenon's capsule aging

• Muscle displacement without LR-SR band rupture

Divergence Paralysis/Insufficiency

Key distinguishing features:

• Always associated with neurological causes:

  • Intracranial hypertension or hypotension

  • Brain tumors

  • Head trauma

  • Multiple sclerosis

  • Chiari malformation

  • Miller-Fisher syndrome

  • Spinocerebellar ataxia type 3 (Machado-Joseph disease)

• MRI is essential for evaluation

Sixth Nerve Palsy

Distinguishing incomitances:

• Esotropia greater than esophoria (distance/near difference)

• Fixation-dependent variation

• Gaze-dependent variation

• Secondary deviation greater than primary (Hering's and Sherrington's laws)

Decompensated Esophoria/Esotropia

• Comitant deviation at distance and near

• Large angle deviation

• Progressive increase over time

• Esophoria decompensates into tropia

Heavy Eye Syndrome (HES) and High Myopia

Characteristics:

• Significant myopic anisometropia

• Convergent vertical strabismus

• More myopic eye typically lower

• May progress to strabismus fixus

• Related to eyeball shape changes in high myopia

• Nasal displacement of superior and inferior rectus muscles

• Downward displacement of lateral rectus muscle

Thyroid Eye Disease (Orbitopathy)

Distinguishing features:

• Affects all orbital structures

• Inflammatory signs: pain on eye movement, chemosis, conjunctival redness

• Functional symptoms: tearing, photophobia, asthenopia, retro-orbital pain

• Various diplopia patterns

• Eyelid retraction (upper > lower)

• Exophthalmos

• True myopathy with restrictive pattern

Myasthenia Gravis

Key characteristics:

• Autoimmune neuromuscular junction disorder

• Variable deviation patterns

• Variable ptosis

• Fatigability with sustained effort

• Poor nerve-to-muscle transmission

• Symptoms worsen with fatigue

Conclusion

Sagging Eye Syndrome represents a significant age-related oculomotor disorder that requires:

Key Points for Clinicians:

1. Non-neurological origin: Unlike many adult-onset strabismus conditions, SES is mechanical, not neurological

2. Progressive nature: The condition typically worsens over time, requiring ongoing management

3. Post-surgical revelation: Often becomes symptomatic after vision-improving procedures

4. Imaging importance: MRI provides crucial diagnostic information about band integrity and muscle displacement

5. Treatment challenges: Requires combination of optical and potentially surgical management

Clinical Significance:

• Affects elderly population with increasing prevalence

• Can be unilateral or bilateral, symmetric or asymmetric

• Causes distance esotropia with near orthophoria initially

• May progress to include vertical and torsional components

• Requires differentiation from neurological causes of diplopia

Management Approach:

• Orthoptic monitoring is essential

• Prism correction often provides initial relief

• Surgical intervention may become necessary

• Patient education about progressive nature is important

The recognition and understanding of SES has significantly improved with advances in orbital imaging and the pioneering work of researchers like Joseph L. Demer. As our population ages, familiarity with this condition becomes increasingly important for ophthalmologists, orthoptists, and other eye care professionals.

Remember: SES ≠ ARDET - While related, these represent different stages of the same pathological processo, with SES being the more advanced form involving complete band rupture rather than just elongation.