Scleral-Fixated Intraocular Lens (SFIOL)

Key points at a glance

Key points of this procedure

• Even in eyes without capsular or zonular support, visual recovery is possible by directly fixing the intraocular lens to the sclera.
• Fixation methods are broadly divided into “suture fixation (suturing)” and “sutureless intrascleral fixation (Yamane method, etc.).”
• The choice of suture material (Prolene or Gore-Tex) directly affects the risk of scleral melting and suture breakage.
• The Yamane method, also called the flange method, is widely used as a sutureless intrascleral fixation technique.
• Postoperative visual prognosis is good, and the safety of corneal endothelial cells and visual acuity is considered equivalent to conventional techniques.
• Long-term complications include suture breakage, scleral melting, intraocular lens tilt/decentration, and infection, which require attention.

1. What is Scleral-Fixated Intraocular Lens (SFIOL)?

Scleral-fixated intraocular lens (SFIOL) is a general term for surgical techniques in which the haptics of an intraocular lens are directly fixed to the sclera in eyes that have lost capsular or zonular support.

Indications

• Trauma: Lens damage with zonular rupture or capsular break
• Intraocular lens dislocation/subluxation: Malposition of the intraocular lens
• Congenital diseases: Connective tissue disorders with lens dislocation such as Marfan syndrome¹⁾
• Intraoperative complications: Posterior capsule rupture during cataract surgery
• Aphakia: Residual cases from the era of extracapsular extraction

SFIOL has good safety and visual prognosis, and long-term follow-up shows outcomes comparable to standard cataract surgery techniques ¹⁾.

Recent reviews have summarized that the visual outcomes and safety of SFIOL are generally equivalent to existing secondary intraocular lens fixation methods ¹⁾.

Q In what situations is SFIOL selected?

A

It is selected for cases where normal in-the-bag fixation is not possible due to defects in the lens capsule or zonules. Typical indications include trauma, congenital lens dislocation such as Marfan syndrome, complications of cataract surgery, and intraocular lens dislocation ¹⁾.

2. Types and Selection of Intraocular Lenses

The choice of intraocular lens for SFIOL varies depending on the surgical technique, axial length, and surgeon experience. The main products are as follows.

CZ70BD

Material: PMMA one-piece lens

Features: Extensive long-term track record. Widely used in suturing techniques (ab externo method).

Note: May require re-suturing in some cases.

Akreos / MX60

Material: Hydrophobic acrylic

Features: Four-point fixation provides high stability. Foldable, allowing small incision surgery.

Note: There is a risk of calcification in eyes with silicone oil ¹⁾.

CT Lucia 602

Material: Hydrophobic acrylic

Features: Haptic design optimized for the Yamane technique (intrascleral fixation).

Note: A dedicated guide is recommended for flange formation.

Carlevale Intraocular Lens

Material: Acrylic

Features: Compatible with 2.2 mm small incision. Unique T-shaped haptics allow sutureless intrascleral fixation ¹⁾.

Note: Concurrent DMEK has also been reported ¹⁾.

Calcification Risk and Management in Small Eyes

Hydrophobic acrylic intraocular lenses (e.g., Akreos) have been reported to calcify in eyes that have undergone vitrectomy with silicone oil use ¹⁾.

Sutureless designs such as the Carlevale IOL have been reported for intrascleral fixation through small incisions and in cases combined with corneal transplantation ¹⁾.

In microphthalmos or severe hypotony, the surgical field is narrow, making standard fixation techniques difficult.

In cases with anatomical constraints such as microphthalmos, modifications in the choice of intrascleral fixation technique and adjunctive procedures are necessary ¹⁾.

3. Surgical Technique

SFIOL fixation methods are broadly classified into suture fixation (suturing) and sutureless intrascleral fixation.

Suture Fixation (Suturing)

Ab externo method (external approach)

This method involves inserting a suture needle from outside the sclera to ligate and fixate the intraocular lens haptics.

• Suitable for PMMA lenses (e.g., CZ70BD)
• Easy to secure the surgical field, with a relatively short learning curve for surgeons
• Suture degradation over time is a concern

Ab interno method (internal approach)

This method involves manipulating from inside the eye to pull the haptics and fixate them to the sclera.

Z-suture method

A technique that uses a unique Z-shaped suture to fixate the haptics to the sclera. It is also applied to congenital lens dislocation.

In children and congenital lens dislocation such as Marfan syndrome, it is important to select a fixation method with long-term stability in mind and to perform long-term follow-up ¹⁾.

Sutureless intrascleral fixation (Yamane technique / flange technique)

This method deforms the tip of the intraocular lens haptics with low heat (forming a flange) and fits it into a scleral tunnel. No sutures are used.

• Standard procedure of the Yamane technique:
  1. Create two scleral tunnels (180° apart)
  2. Guide the haptics from the anterior chamber to the outside of the sclera using a 27G needle
  3. Pull the haptics out and create a flange at the tip
  4. Push back into the sclera to fixate

The use of a bent needle has been reported to improve accuracy¹⁾.

Key intraoperative points

In the Yamane technique, if the insertion angle of the 27G needle and the heat amount for flange formation are not uniform, it can lead to intraocular lens tilt or decentration. Intraoperative confirmation of the fixation position using AS-OCT improves accuracy³⁾.

Intraoperative evaluation with AS-OCT

Intraoperative monitoring using anterior segment OCT (AS-OCT) is gaining attention as a means to objectively assess the quality of fixation.

Intraoperative and postoperative evaluation with AS-OCT is used as an adjunct to objectively confirm intraocular lens tilt or decentration³⁾.

The following shows a comparison between sutured scleral fixation and intrascleral fixation.

Item	Sutured fixation	Intrascleral fixation
Suture	Required	Not required
Incision width	Large (PMMA, etc.)	Small incision possible
Long-term risk	Suture breakage	Haptic deformation

Subhyaloid hemorrhage (SH) risk

During SFIOL surgery, subhyaloid hemorrhage (SH) is a possible complication.

Since complications such as subhyaloid hemorrhage can occur during SFIOL surgery, it is important to stabilize the needle insertion angle and haptic manipulation ¹⁾.

Q Which is better: the Yamane technique or sutured fixation?

A

Both have advantages and disadvantages, and it is not possible to say which is superior. The Yamane technique has no risk of suture breakage and allows small incisions, but requires confirmation of haptic material compatibility. Sutured fixation has a proven track record with PMMA, etc., but long-term suture degradation is a problem ¹⁾.

4. Suture materials

In SFIOL procedures requiring sutures, the choice of suture material greatly affects long-term outcomes.

Prolene (polypropylene) suture

This has been the most widely used suture material traditionally.

• Breakage rate: varies widely from 0% to 27.9% according to literature reports
• Time to breakage: several years to more than 10 years postoperatively
• Hydrolysis and photo-oxidation due to long-term use are considered causes of breakage

With Prolene suturing, there is a possibility of suture degradation and need for refixation in the long term postoperatively, and long-term observation including corneal complications is necessary²⁾.

Gore-Tex (expanded polytetrafluoroethylene; ePTFE) suture

This material has high suture strength and durability and has attracted attention as an alternative to Prolene.

• Higher tensile strength compared to polypropylene
• High resistance to in vivo degradation, expected long-term maintenance

However, an association with scleral melt has been reported, and caution is required when using it.

While Gore-Tex sutures are expected to provide strength and durability, rare complications such as scleral melt have been reported, and long-term follow-up is necessary²⁾.

Infection risk

Regardless of the type of suture material, exposed sutures can become a route of infection.

Since exposed sutures can become a route of infection, conjunctival coverage and confirmation of signs of infection are important in cases of suture fixation including Gore-Tex²⁾.

The main characteristics of suture materials are compared below.

Material	Durability	Scleral melt	Infection
Prolene	Breakage present	Low	Caution if suture exposed
Gore-Tex	High strength	Reported2)	Fungal infection reported2)

Q Can suture-related problems be avoided with sutureless intrascleral fixation?

A

Sutureless intrascleral fixation such as the Yamane technique does not cause suture breakage or suture-related infection. However, other long-term risks such as haptic instability or dislocation exist¹⁾³⁾.

5. Prognosis and Complications

Visual Prognosis

Visual prognosis after SFIOL surgery is generally good¹⁾. In congenital lens dislocation treated with the Z-suture technique, 20/20 vision was achieved at 5-year follow-up¹⁾. In microphthalmic cases, good visual acuity has been reported with a combination of the Yamane and glued techniques¹⁾.

Major Complications

• Vitreous hemorrhage (VH): May occur during surgery. Reported rate is approximately 0.5%¹⁾.
• Intraocular lens tilt/decentration: Caused by suture loosening or uneven flange fixation³⁾.
• Optic inversion: The optic of the intraocular lens is flipped posteriorly, causing refractive error.

Intraocular lens malposition such as optic inversion can cause refractive error and visual impairment, so intraoperative and early postoperative position confirmation is important²⁾.

• Infection/endophthalmitis: Caused by suture exposure or intraoperative manipulation. Cases of fungal endophthalmitis have been reported²⁾.
• Scleral melting: Reported as a foreign body reaction with Gore-Tex sutures²⁾.
• Corneal endothelial cell loss: Endothelial damage due to lens contact, inflammation, or surgical manipulation. Long-term follow-up is necessary²⁾.
• Brown-McLean syndrome: Peripheral corneal edema occurring after aphakia or long-term intraocular lens fixation²⁾.

After Prolene suturing, suture breakage or lens dislocation may occur in the long term, so regular observation is needed even in the late period²⁾.

Postoperative follow-up precautions

• If suture exposure is noted, infection risk is high. Prompt evaluation at a specialized facility is necessary.
• Suture breakage or lens dislocation may occur even in the late postoperative period (over 10 years). Do not neglect regular eye examinations.
• In cases using Gore-Tex sutures, watch for signs of scleral melting (redness, pain, changes around the suture).

Q How long should follow-up be continued after SFIOL surgery?

A

Suture breakage, scleral melting, or lens decentration may occur more than 10 years after surgery²⁾. Even if good visual acuity is achieved postoperatively, it is essential to continue regular eye examinations.

6. Pathophysiology/Mechanism

In eyes with defects in the lens capsule or zonules, standard CPS (capsular bag fixation) or ACS (ciliary sulcus fixation) cannot be selected. In such cases, the optical system is established by directly fixing the intraocular lens haptics within the scleral stroma.

The stability of intrascleral fixation depends on the tissue strength of the sclera. In the Yamane technique with flange fixation, the thermally deformed haptic tip is mechanically engaged within the scleral tunnel. In suture fixation, support is provided by the tensile strength of the suture and friction with the tissue. In either method, changes in fixation strength (suture degradation, tissue remodeling) may occur over the long term.

Scleral melting (Gore-Tex suture) results from a chronic inflammatory reaction to a foreign body, with necrosis and thinning of the scleral tissue around the suture ²⁾. Corneal endothelial damage involves a combination of factors including intraoperative instrument contact, postoperative inflammation, and chronic irritation from IOL malposition ²⁾.

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7. Latest Research and Future Perspectives

For patients: Please read this

The following content is currently under research or in clinical trials and is not standard treatment available at general hospitals. It is reference information for professionals regarding future medical developments.

Evolution of Small-Incision and Sutureless Techniques

Technical improvements continue for sutureless fixation methods such as the Yamane technique and Carlevale intraocular lens. The Carlevale IOL can be inserted through a 2.2 mm incision, and its indications are expanding, including reports of simultaneous performance with DMEK ¹⁾.

Intraoperative and Postoperative Evaluation with AS-OCT

Intraoperative and postoperative AS-OCT evaluation is considered effective for early detection of IOL decentration ³⁾. Future applications for intraoperative real-time guidance are expected.

Expanded Indications for Pediatric and Difficult Cases

Fixation techniques for cases with anatomical constraints such as microphthalmos or congenital lens dislocation have been reported ¹⁾. Long-term follow-up of visual function development and complications remains a future challenge.

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8. References

1. Zhang Y, et al. Clinical Outcomes in Scleral Fixation Secondary Intraocular Lens with Yamane versus Suture Techniques: A Systematic Review and Meta-Analysis. J Clin Med. 2024;13(11):3071. doi:10.3390/jcm13113071. https://pmc.ncbi.nlm.nih.gov/articles/PMC11173341/
2. Błagun N, Krix-Jachym K, Rękas M. Comparison of Safety and Efficacy of Four-Point Scleral Intraocular Lens Fixation and the Yamane Technique. Ophthalmol Ther. 2024;13(7):1955-1966. doi:10.1007/s40123-024-00962-7. https://pmc.ncbi.nlm.nih.gov/articles/PMC11178701/
3. Shelke K, Rishi E, Rishi P. Surgical outcomes and complications of sutureless needle-guided intrascleral intraocular lens fixation combined with vitrectomy. Indian J Ophthalmol. 2021;69(9):2317-2320. doi:10.4103/ijo.IJO_1636_20. https://pmc.ncbi.nlm.nih.gov/articles/PMC8544105/