synechiae

DEFINITION of synechiae

In ophthalmology — by far the most common context — synechiae refer to adhesions involving the iris. There are two primary anatomical subtypes. Anterior synechiae (PAS when peripheral) are adhesions between the iris and the corneal endothelium or the trabecular meshwork in the iridocorneal angle. These are particularly dangerous because they can progressively obstruct aqueous humor outflow, leading to secondary angle-closure glaucoma and potentially irreversible optic nerve damage. Posterior synechiae are adhesions between the posterior surface of the iris and the anterior lens capsule (or the anterior vitreous face in aphakic patients). They form almost exclusively in the setting of anterior uveitis, as inflammatory exudate and fibrin deposited in the posterior chamber organize and bind the iris to the lens. Over time, extensive posterior synechiae can encircle the entire pupillary margin, producing a condition known as seclusio pupillae (pupillary seclusion), which creates a functional pupillary block. This blocks aqueous flow from the posterior to the anterior chamber, causing iris bombé — forward bowing of the peripheral iris — and subsequent secondary angle closure. Further progression can result in occlusio pupillae, wherein a fibrovascular membrane completely occludes the pupillary opening itself. The formation of synechiae is driven by the inflammatory cascade: fibrin-rich exudate deposits on iris and lens surfaces, fibroblasts infiltrate, and organized fibrous adhesions result. Common ophthalmic causes include anterior uveitis (the most frequent), trauma, prolonged shallow anterior chamber (post-surgical), intraocular surgery, corneal disease with peripheral anterior adhesion formation, and neovascular conditions.

In otolaryngology, synechiae in the nasal cavity refer to fibrous bands between the nasal septum and lateral nasal wall (inferior or middle turbinate), typically as a complication of septal surgery, turbinate reduction, trauma, or chronic infection. Middle ear synechiae (coded as adhesive middle ear disease) occur when the tympanic membrane or ossicular chain adheres to the medial wall of the middle ear, typically secondary to chronic otitis media with effusion or chronic negative middle ear pressure — impairing sound conduction and producing conductive hearing loss.

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ETYMOLOGY of synechiae

greek The word derives from the Greek synecheia (συνέχεια), from syn- (σύν) meaning “together” or “with,” and echein (ἔχειν) meaning “to hold” or “to have.” Combined, the literal meaning is “a holding together” — perfectly describing the pathological binding of normally separate structures. The term entered medical Latin and was adopted into English anatomical and pathological nomenclature in the 17th-18th centuries, initially applied almost exclusively to ocular adhesions.

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RELATED TERMS

Ophthalmology:

• Uveitis / Iridocyclitis — The most common inciting condition for posterior synechiae formation
• Anterior chamber inflammation — Generates the fibrin scaffold upon which synechiae form
• Fibrin — The inflammatory protein that forms the initial “glue” preceding organized synechiae
• Gonioscopy — The examination technique used to directly visualize anterior synechiae and assess angle involvement
• Trabecular meshwork — The drainage structure obstructed when peripheral anterior synechiae (PAS) form
• Secondary angle-closure glaucoma — The most serious complication of anterior synechiae
• Iris bombé — Pathognomonic forward bowing of the iris caused by 360° posterior synechiae blocking aqueous flow
• Laser peripheral iridotomy (LPI) — Procedure used to relieve pupillary block caused by synechiae-induced iris bombé
• Cycloplegia / Mydriatics — Pharmacologic dilation used therapeutically to prevent or break early posterior synechiae
• Keratic precipitates (KPs) — Inflammatory deposits on the corneal endothelium; co-occur with synechiae in uveitis
• Pupillary membranes — Related condition; persistent or acquired fibrovascular membranes across the pupil

Otolaryngology:

• Adhesive otitis media — Chronic middle ear condition producing tympanic-to-medial wall adhesions
• Nasal synechia — Post-surgical or post-traumatic fibrous bands across the nasal passage
• Septal perforation — Related complication of nasal surgery that may coexist with nasal synechiae

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CODING and NUANCES

ICD-10-CM CODES

Ophthalmic Synechiae — Anterior (H21.51x)

H21.511 — Anterior synechiae (iris), right eye H21.512 — Anterior synechiae (iris), left eye H21.513 — Anterior synechiae (iris), bilateral H21.519 — Anterior synechiae (iris), unspecified eye

Ophthalmic Synechiae — Posterior (H21.54x)

H21.541 — Posterior synechiae (iris), right eye H21.542 — Posterior synechiae (iris), left eye H21.543 — Posterior synechiae (iris), bilateral H21.549 — Posterior synechiae (iris), unspecified eye

Ophthalmic Synechiae — Unspecified Adhesions of Iris (H21.50x)

H21.501 — Unspecified adhesions of iris, right eye H21.502 — Unspecified adhesions of iris, left eye H21.503 — Unspecified adhesions of iris, bilateral H21.509 — Unspecified adhesions of iris and ciliary body, unspecified eye

Related Ophthalmic Sequelae / Concurrent Conditions

H21.41 — Pupillary membranes, right eye H21.42 — Pupillary membranes, left eye H21.43 — Pupillary membranes, bilateral H21.40 — Pupillary membranes, unspecified eye H40.211 — Acute angle-closure glaucoma, right eye (sequela of anterior synechiae/iris bombé) H40.212 — Acute angle-closure glaucoma, left eye H40.213 — Acute angle-closure glaucoma, bilateral H40.219 — Acute angle-closure glaucoma, unspecified eye

Otolaryngologic — Adhesive Middle Ear Disease (Synechiae equivalent)

H74.11 — Adhesive right middle ear disease H74.12 — Adhesive left middle ear disease H74.13 — Adhesive middle ear disease, bilateral H74.19 — Adhesive middle ear disease, unspecified ear

⚠️ Coder’s Note: For ocular synechiae, always code the underlying cause (e.g., uveitis, iridocyclitis) as an additional code when documented. Posterior synechiae are almost always associated with anterior uveitis — the uveitis code should typically be sequenced first as the reason for the encounter unless the synechiae themselves are the primary focus of treatment. Note that N85.6 (intrauterine synechiae) is a 5-character code — this category does not extend to 7 characters and N85.6 is the valid, complete, HIPAA-compliant code.

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CPT CODES (Relevant to Synechiae Workup & Management)

Ophthalmic Examination & Diagnostics

92004 — Ophthalmological services, new patient, comprehensive 92014 — Ophthalmological services, established patient, comprehensive 92020 — Gonioscopy (essential for directly visualizing and grading anterior synechiae/PAS at the angle) 92250 — Fundus photography with interpretation and report 92132 — Scanning computerized ophthalmic diagnostic imaging, anterior segment, unilateral (OCT anterior segment — used to assess angle anatomy and synechiae) 76510 — Ophthalmic ultrasound, B-scan (useful when media opacity prevents direct visualization)

Ophthalmic Surgical / Procedural

66761 — Iridotomy/iridectomy by laser surgery (e.g., for iris bombé/pupillary block from seclusio pupillae) 66680 — Repair of iris, ciliary body (for synechiae repair/lysis during open procedures) 65860 — Severing adhesions of anterior segment, laser technique (laser lysis of anterior synechiae) 65870 — Severing adhesions of anterior segment, incisional technique — anterior approach (surgical synechiolysis) 65875 — Severing adhesions of anterior segment, incisional technique — posterior approach 65880 — Severing adhesions of anterior segment, incisional technique — corneal section (more extensive synechiolysis)

Otolaryngologic

30999 — Unlisted procedure, nose (used for nasal synechiae lysis when no more specific code applies) 69799 — Unlisted procedure, middle ear (used for middle ear adhesion lysis when no more specific code applies)

💡 Coder’s Tip: CPT 65860 (laser lysis) vs. 65870/65875/65880 (incisional synechiolysis) — the distinction depends entirely on surgical approach and technique documented by the physician. Make sure operative reports clearly state laser vs. incisional technique and anterior vs. posterior approach before selecting. For 58558, confirm the operative report documents actual lysis of adhesions and not merely diagnostic visualization, which would fall under 58555 instead.

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All ICD-10-CM codes verified as valid for HIPAA transactions.

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DERIVATIONS of synechiae

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Query functionality

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Med roots Appendix A Prefixes Appendix B Combining Forms Appendix C Suffixes Appendix D Suffix forms