Anophthalmic Socket Syndrome / Post-enucleation Socket Syndrome is a condition in which the socket becomes atrophic and sunken after enucleation or evisceration. It is characterized by redistribution of orbital fat, ptosis, deep superior sulcus deformity, lower eyelid malposition, and lagophthalmos. In addition to cosmetic problems, it causes difficulty retaining the ocular prosthesis.
The average volume of the eyeball is about 7.2 ml (a sphere 24 mm in diameter), and the total orbital volume is measured at about 24 ml1). The volume deficit after enucleation reaches 7.0–9.0 ml (average 7.9 ml)1). This deficit is replaced with an orbital implant and an ocular prosthesis, but if the replacement is inadequate or if the implant and orbital tissues atrophy over time, socket hollowing occurs.
Post-enucleation socket syndrome (PESS) is defined as a complex set of changes after enucleation, including difficulty retaining the prosthesis and poor cosmetic appearance2).
After enucleation, orbital volume decreases by about 7–9 ml. If the orbital implant is insufficient, or if fat atrophies over time, the orbit becomes sunken and it becomes difficult to retain the prosthesis. After radiation therapy, atrophy tends to progress further, and in children, underdevelopment of the orbital bones is also added.
The pathology of anophthalmic socket depression is classified into the following three types.
| Type | Main problem | First-line treatment |
|---|---|---|
| Conjunctival fornix contracture type | The conjunctival sac is too narrow for the prosthetic eye to fit | Conjunctival fornix expansion surgery (full-thickness skin graft) |
| Orbital depression type | Insufficient orbital volume | Augmentation procedure (DFG, bone graft, artificial materials) |
| Mixed type | Combination of both | Stepwise treatment (expansion surgery → augmentation surgery) |
Conjunctival socket contracture type
Main condition: The conjunctival socket becomes narrow and shallow, and the prosthetic eye no longer fits properly.
Treatment: Conjunctival socket expansion surgery is indicated, in which the conjunctival socket is dissected upward, downward, left, and right, and a full-thickness skin graft is wrapped around the prosthetic eye and inserted.
Orbital hollowing type
Main condition: Due to insufficient orbital volume, the orbital area moves backward and becomes sunken.
Treatment: Augmentation with autologous tissue (dermal fat, iliac bone, costal cartilage) or artificial materials (hydroxyapatite, silicone) is indicated.
Mixed type
Main condition: Both conjunctival socket contracture and orbital hollowing are present.
Treatment: Conjunctival socket expansion surgery is usually performed first, followed by stepwise orbital augmentation surgery.
After radiotherapy (and after surgery for malignant tumors such as retinoblastoma), scarring of the orbital tissues is added, and the hollowing becomes especially pronounced. In children, facial asymmetry and orbital underdevelopment are also seen.
It can be caused by contracture of the conjunctival sac (the space that holds the prosthetic eye becomes smaller), a sunken orbit (the lower support is not sufficient), or both. It is important to see an ophthalmologist (an oculoplastic surgeon) so they can assess the size of the conjunctival sac and the orbital volume.
Anophthalmic socket atrophy occurs as a long-term complication after enucleation or evisceration. The rate of onset and the speed of progression are affected by various factors.
Type of orbital implant and risk of exposure: After enucleation using porous polyethylene (MEDPOR) or hydroxyapatite, implant exposure occurs in 1.5–21.6%; after evisceration, it occurs in 0–3.3%3). Implant exposure or movement causes secondary changes in orbital volume and worsens sunken appearance.
Pediatric cases: Normal development of the orbital bones requires the presence of the eye, and enucleation in early childhood can lead to underdevelopment of the orbit. Because orbital volume reaches about 80% of adult size by age 56), management during this period is especially important.
After radiation therapy: Fibrosis and vascular damage in the orbital tissues accelerate atrophy. In children treated during the growth period, underdevelopment of the facial bones is also added.
No implant / implant extrusion: If no orbital implant is inserted, or if the implant is extruded, orbital fat atrophy and redistribution progress and the sunken appearance becomes more noticeable.
Evaluate orbital hollowing, ptosis, deepening of the upper eyelid sulcus, lower eyelid displacement, and the presence and degree of lagophthalmos.
Measure the positional difference between the healthy eye and the prosthetic-eye side, and objectively quantify the degree of hollowing.
Treatment is selected according to the type of condition (conjunctival sac contracture type, orbital hollowing type, mixed type).
Indicated when the conjunctival sac is contracted or narrowed and the prosthetic eye does not fit.
Procedure:
| Type | Features | Exposure risk |
|---|---|---|
| Porous polyethylene (MEDPOR) | Good vascular ingrowth and tissue integration | Moderate |
| Hydroxyapatite | Osteoconductive, highly stable | Risk of surface exposure |
| Silicone sphere | Low cost, easy to shape | Slightly higher |
| Dermis fat graft (DFG) | Autologous tissue, no foreign-body reaction | Low |
If exposure of the orbital implant occurs, salvage with a dermis fat graft is effective4).
DFG is an orbital reconstruction method using autologous tissue; it does not cause foreign-body reaction and is an excellent procedure with a low risk of orbital implant exposure4).
Graft components:
Harvest site (hairless area preferred):
Set the graft size 10–30% larger than the orbital volume. If it is too large, it can cause pressure necrosis; if too small, it can lead to atrophy and recurrent hollowing.
Key points of the procedure:
DFG outcomes5):
| Indicator | Primary DFG | Secondary DFG |
|---|---|---|
| Good eyelid position | 83.3% | 37.5% |
| Fat atrophy rate | 5–10% | 20–40% |
| Good prosthetic eye movement | 83.3% | 100% |
| Complication rate (overall) | 58.8% (most were mild and resolved on their own) | — |
Primary DFG (performed at the same time as enucleation) has a better prognosis for eyelid position than Secondary DFG (secondary reconstruction)5).
This is an autologous tissue graft in which dermis and fat are taken from the buttock or inner thigh and transplanted into the orbit. There is no foreign-body reaction, and the risk of implant exposure is low. The conjunctival epithelium covers the dermal surface in 4–6 weeks, after which the prosthetic eye is fitted. If it shrinks again, regrafting is also possible.
| Material | Advantages | Disadvantages |
|---|---|---|
| Dermis fat | Autologous tissue, low exposure risk, possible regrafting | Risk of atrophy over time |
| Iliac bone block | Fits bone atrophy and is firm | Partial resorption and donor-site complications |
| Costal cartilage | Autologous tissue and easy to shape | Leaves a scar on the chest |
| Hydroxyapatite | Osteoconductive and stable | Risk of foreign body reaction and surface exposure |
| Silicone block | Inexpensive and easy to process | Risk of movement and foreign body reaction |
| Microsurgical flap | Can transplant large amounts of tissue | Highly invasive, long operation |
For orbital bony atrophy, grafting an iliac bone block or crushed iliac bone is suitable. For less severe depression, a dermis-fat graft is relatively easy to harvest and also makes the prosthetic socket softer, so it is a good option.
Selection of donor site: Even if scars remain on the iliac crest or groin, the skin incision can be placed where it can be hidden by underwear or a swimsuit.
Conjunctival sac expansion surgery
Indications: Contracted conjunctival sac type.
Procedure: Wrap a full-thickness skin graft inside out around a thin ocular prosthesis and insert it. Fix the lower fornix deeply to the periosteum of the infraorbital rim.
Donor site: Groin or lower abdomen (a position hidden by underwear or a swimsuit).
Dermis-fat graft (DFG)
Indications: Moderate orbital hollowing, salvage for exposed orbital implant, chronic pain.
Procedure: Attach the extraocular muscles to the dermal button. Fit the prosthesis after leaving the conformer in place for 3–4 weeks.
Advantages: Can be re-implanted if atrophy recurs. Low risk of exposure.
Bone grafts and artificial materials
Indication: Severe socket depression with marked bony atrophy.
Material selection: Iliac bone (bony atrophy), hydroxyapatite (stability), silicone block (low cost; deep insertion is important).
Note: If silicone is not inserted deeply, there is a risk of movement and exposure.
Dermis-fat grafting can be repeated if atrophy recurs. However, repeated surgery may lead to scarring of the conjunctival sac. The choice of material should be discussed with an oculoplastic specialist.
The volume loss after eye removal reaches 7.0–9.0 mL (average 7.9 mL)1). Inserting an orbital implant makes up much of this volume, but the implant alone cannot fill the entire orbit, so the remaining deficit is covered by an artificial eye (an external prosthesis placed over the socket base). If the implant is inadequate, extruded, or displaced, or if the orbital fat shrinks over time, a depression develops.
Radiation to the orbit causes fibrosis and vascular damage in orbital tissues. Fibrotic tissue loses elasticity and shrinks, causing the entire socket to become smaller. In children, radiation can also impair orbital bone growth, leading to marked facial asymmetry later in adulthood.
Normal development of the orbital bones requires the presence of the eye. When the eye is lost, the mechanical stimulus to the orbit is lost and orbital bone growth is delayed. By age 5, orbital volume reaches about 80% of the adult size6), so during this period it is especially important to manage the orbital implant and artificial eye to maintain orbital volume. As the child grows, the size of the artificial eye and implant must be adjusted regularly.
Exposure occurs when the conjunctiva and Tenon’s capsule over the implant become thin and necrotic. Porous materials promote tissue integration through vessel ingrowth, but exposure risk remains if the surface tissues are thin or if blood flow is impaired by surgical manipulation. The dermis-fat graft has the lowest exposure risk because blood flow is maintained in autologous tissue4).
Fat atrophy begins immediately after removal of the eye, and without an implant the hollowing progresses especially rapidly. Even with an implant, hollowing gradually advances because of aging, gravity, and pressure from the weight of the artificial eye. This change is further accelerated after radiation therapy and during periods of growth.
Long-term outcomes of DFG: In a case series of 34 cases (Jovanovic et al.), a complication rate of 58.8% was reported, but most were mild and resolved on their own4). DFG salvage for implant exposure was indicated in 67.7% of cases, making it an effective salvage option4).
5-fluorouracil (5-FU) injections: An approach has been reported in which an antimetabolite is used as a pre-treatment for severe contracted socket, softening scar tissue before DFG is performed7).
Use for chronic pain: There are reports that chronic socket pain improves by removing the orbital implant and replacing it with DFG8).
Expandable hydrogel implant (HEMA): Research is being conducted on stepwise expanding HEMA implants to promote orbital growth in children.
Future challenges: It is necessary to identify predictors of long-term atrophy in DFG, standardize the optimal graft size, and compare long-term outcomes by material of the ocular prosthesis base (RCT).
