Fuchs Endothelial Dystrophy Treatment & Management

Patients who have Fuchs endothelial dystrophy and clear corneas need no treatment. It is only when the corneal decompensation starts that medical treatment becomes necessary. This treatment is necessary until it is not possible to preserve good vision; at that point, keratoplasty is necessary.

• Dehydrating agents

  • Sodium chloride 5% eye drops are instilled 4-6 times during the day, especially in the early hours of the day and less frequently in the evening. Sodium chloride ointment is used at bedtime.
  • Glycerine can be used for diagnostic purposes. It causes rapid dehydration of the cornea and clears the vision. Certain patients are able to use it for therapeutic purposes, but it is rather uncomfortable. It is instilled many times a day, as needed.
• Use of warm dry air (evaporation): A hair dryer, kept at arm's distance, can be used to blow warm air over the cornea for 5-10 minutes upon awakening. Drying of the cornea may improve the vision of the patient for some time.
• Lowering the intraocular pressure (IOP) is useful when it is even mildly raised. It occasionally helps even when the pressure is normal, especially in borderline cases of corneal decompensation. Topical carbonic anhydrase inhibitors should be avoided as it hinders the activity of endothelial pump.
• Topical nonsteroidal anti-inflammatory drug (NSAID): Diclofenac 0.1% and ketorolac 0.5% drops may help to alleviate symptoms (eg, itching, burning, gritty sensation) but may increase the risk of poor epithelial healing and subsequent corneal melting.
• Supportive treatment for ruptured bullae

  • Anterior stromal punctures may be indicated.
  • Multiple ablation pits with Fugo blade can be used.
  • Soft contact lenses can be useful in cases of bullae formation.
  • Cycloplegics, local antibiotics, and pad and bandage treat the eye for a couple of days.
  • Excimer laser phototherapeutic keratectomy, amniotic membrane graft, or a conjunctival flap can also be considered.

Failing vision in the presence of epithelial edema and stromal haze, which cannot be treated by the instillation of 5% sodium chloride drops and ointment, necessitates recourse to surgery.

A selection has to be made between the following 2 options: (1) keratoplasty alone, when no cataract formation is present, or (2) if a cataract is present and adds significantly to visual disability and specular endothelial microscopy results suggest the need for a corneal graft, then a combined corneal transplant, cataract extraction, and lens implant procedure should be performed.

Penetrating keratoplasty (PK) with or without cataract surgery has been the criterion standard for treatment of Fuchs endothelial dystrophy for the past 100 years. PK involves replacement of whole cornea, although only endothelial layer is defective. In last few years, major advances in this field have made replacement of endothelial layer possible without disturbing normal anterior structures of cornea using endothelial keratoplasty. Descemet membrane stripping automated endothelial keratoplasty (DSEK) involves transplant of healthy endothelial layer along with minimal posterior corneal stroma. Descemet membrane endothelial keratoplasty (DMEK) is the transplant of endothelial cells along with Descemet’s membrane only.^[7]

Patients who undergo DSEK regain early and more superior visual acuity than patients who undergo PK due to lack of surface sutures.^{[8, 9]} These eyes are structurally stronger and more resistant to postoperative traumatic injury, and no suture-related graft infection or graft rejection occurs.

A study by van der Meulen et al found that straylight pre-DSEK can be a useful clinical metric to predict postoperative improvement, especially in cases where the preoperative visual acuity is near 20/20. Straylight also improved more in younger eyes than in older eyes after the procedure.^[10]

Frequent visits are no longer required, as is the case in patients who undergo PK. DSEK can be combined with cataract surgery (ie, phacoemulsification or manual small incision cataract surgery) in patients with associated cataracts. In patients with associated corneal stromal scaring, PK is still the treatment of choice.

Descemet membrane stripping and endothelial keratoplasty

Preoperative assessment is required mainly to rule out glaucoma and posterior segment abnormality. Careful slit lamp examination is required to check anterior chamber depth and rule out any associated angle anomalies. Anterior segment optical coherence tomography (OCT) and ultrasound biomicroscopy (UBM) can be helpful in patients having very hazy view. Appropriate methods should be used to check IOP. Ultrasound B scanning is helpful in ruling out gross posterior segment abnormality and disc excavation.

Preparation of donor tissue includes the following:

• The target is to prepare a donor disc of the required diameter with a posterior one third stroma and Descemet membrane with healthy endothelial cells. Preparation can be manual or automated (Microkeratome); the latter is DSAEK. A femtosecond laser can also be used to prepare donor lenticule (FS-DSEK). With the present data, all methods seem comparable in terms of clinical outcome, although this has yet to be clearly established. Manual dissection is most cost effective and is performed using artificial anterior chamber and blunt dissectors.
• Steps of manual preparation of donor disc include the following:

  • Donor tissue is mounted on artificial anterior chamber, and the epithelium is removed to improve the view.
  • Manual lamellar dissection is performed at approximately two thirds depth with 2 blunt dissectors (straight and curved).
  • Donor tissue is removed from artificial anterior chamber, and the desired diameter is punched.

Preparation of the recipient bed includes the following:

• Surgery is performed under conventional peribulbar anesthesia, although it can be done under topical anaesthesia as well.
• Preoperatively, pilocarpine 2% is used to constrict the pupil when only DSEK is planned and the pupil is dilated; cataract surgery is also required.
• Three 1-mm side-ports are made at 6-o'clock, 10-o'clock, and 2-o'clock positions. The 10-o'clock and 2-o’clock incisions are for Descemet membrane stripping and to manipulate and unfold the donor lenticule. The 6-o’clock incision is used for anterior chamber (AC) maintainer (ACM). Avoiding any kind of viscoelastic substance is desirable, and, if required, use only cohesive viscoelastic agent.
• Trypan blue (0.06%) solution is used to stain the diseased endothelium. Circular scoring of the Descemet membrane is performed with a reverse Sinskey hook corresponding to epithelial template mark. Scoring (touching the membrane with optimal pressure) can be performed in a complete circle form (Descemetorrhexis) or in a "can opener" form. Scoring makes a cut in the Descemet membrane, which can later be completely stripped off with the help of the hook.
• A 5-mm to 5.5-mm sclerocorneal tunnel is prepared similar to making a tunnel in manual small incision cataract surgery. Making the tunnel temporal is desirable, so as to induce minimal astigmatism.
• If required, cataract surgery with intraocular lens implantation (phacoemulsification or manual small incision cataract surgery) is performed at this stage because the view is comparatively better after removing the Descemet membrane and epithelium.
• If viscoelastic agent is used, it is thoroughly and carefully washed out with balanced salt solution (BSS) using an irrigation/aspiration cannula, and an AC is then well formed with BSS.

Transplantation of the donor lenticula includes the following:

• A punched corneal button of desired diameter is transferred on the recipient's corneal surface with the endothelial side up. The endothelial side is coated by a thin layer of cohesive viscoelastic substance. The posterior lamella of the donor tissue is folded into an asymmetric "taco-shape," in a 60% to 40% ratio with a fine forceps grasping only the edge of the donor lenticule. This "taco" is gently held at the leading edge with capsulorrhexis forceps with 60% side up and is inserted through the tunnel into the AC like a foldable intraocular lens. The platforms of the capsulorrhexis forceps do not oppose, thereby minimizing the crush injury to the donor endothelium.
• A bent 30-gauge needle (reverse cystitome) on a 2-cc air syringe is used to gently engage the posterior edge of the anterior flap of the folded donor lenticule and fixate it against the host corneal stroma. While maintaining fixation, an air bubble is injected posterior to the graft, causing it to unfold. Donor lenticule is centered by massaging over the cornea with an iris repositor or round cannula after filling the anterior chamber completely with air. Air can be replaced with saline after 1 hour. A bandage contact lens is given in all cases.
• The eye is patched and the patient is instructed to lie supine for at least 12 hours.

Patients can be discharged after 48 hours. Postoperative medications include topical steroids (prednisolone acetate or betamethasone) in tapering doses, starting from 8 times per day to 1 time per day over 6 months before finally administering topical fluorometholone 1 time per day indefinitely. Few surgeons consider completely discontinuing topical steroids.

Penetrating keratoplasty

The following is indicated in PK:^[11]

• Preoperative management

  • Patients with aphakic bullous keratopathy: Contract the pupil with 3 instillations of 1-2% pilocarpine drops every 5 minutes.
  • Triple procedure: Three drops each of 1% cyclopentolate, 2.5% oxymetazoline, and flurbiprofen sodium, preoperatively.
  • High-risk vascularized cornea: Oral prednisolone (1 mg/kg/d) is started 4 days preoperatively and is tapered over 2 weeks postoperatively.
• Anesthesia

  • Local anesthesia with 50/50 mixture of 0.75% bupivacaine and 2% lidocaine and 150 U of hyaluronidase.
  • Anesthesia may be retrobulbar or peribulbar. Good hypotony should be obtained with a mechanical pressure device (eg, Honan balloon, Super Pinky ball, mercury bag).
  • After thoroughly ascertaining cardiovascular status, general anesthesia may be used in selected cases.
• Preparation of the recipient

  • Position the head to obtain good red reflex and optical centration. Ocular compression and lateral canthotomy may minimize external pressure on the eyeball. Jaffe wire lid speculum is used to open the eye.
  • Flieringa ring of appropriate size is fixed 2 mm from the limbus with 4-6 interrupted 6-0 black silk sutures. Four 4-0 silk sutures are used to fix the ring to the drape. Determine donor size. A size between 7.75 mm and 8.25 mm typically is selected. The donor button should be 0.25-0.50 mm larger.
• Preparation of the donor eye

  • Allow the donor eye to come to room temperature, about 30 minutes prior to use.
  • Use a posterior punch trephine to cut the button from the endothelial side.
  • Transfer the button, endothelial side up, to a Petri dish containing a few drops of balanced salt solution or corneal preservation medium. Cover the disc.
• Preparing the recipient bed

  • The cornea is dried with the cellulose sponge.
  • The center of the cornea is marked with an angled Sinskey hook.
  • Use the cross-wires to center the trephine. The centration is evaluated by lightly touching the cornea with the trephine.
  • A partial thickness incision is made by turning the trephine 8 quarter turns in a clockwise direction. This procedure creates a 0.5-mm deep incision.
  • For later use, make a stab incision at the limbus to form the anterior chamber.
  • To mark the entry of sutures on the recipient cornea, use 8 or 12 blade radial incision marker.
  • Enter the anterior chamber along the wound margin. Use a delicate scissors to cut the rest of the cornea, cutting perpendicular to the iris plane.
  • Ensure that the Descemet membrane is removed.
  • Remove any tags along the edge.
  • Place viscoelastic material over the iris-lens diaphragm.
  • Transfer the donor button to the prepared site, using a 0.12-mm forceps.
• Graft suturing

  • During the procedure, use the paracentesis incision to deepen the anterior chamber with saline. Place the first suture at the 12-o'clock position to stabilize the corneal button. Place sutures (in this order) at the 6-o'clock, 3-o'clock, and 9-o'clock positions. Alignment should be most carefully completed, especially at the 6-o'clock position.
  • Take bites at 1.5 mm, on both sides of the incision line. The depth should be 50-90% of the corneal thickness. Bury the knots.
  • Use a 12-bite running suture of 10-0 nylon in an antitorque manner. Adjust tension to equalize apposition throughout the wound. Sixteen interrupted sutures also may be used.
  • Intraoperative keratometry may be performed. Deepen the anterior chamber with saline. Remove viscoelastic. Test the wound for tightness. Then, bury the knot.
  • Remove the Flieringa ring.
  • Give a subconjunctival injection of vancomycin (1 mg), dexamethasone (1 mg), and gentamicin (20 mg).
  • Patch the eye after applying dexamethasone, polymyxin B, and bacitracin ointment. Apply a plastic shield.
• Postoperative management

  • On the first postoperative day, check IOP and examine the epithelium integrity and wound anatomy. If the pressure is higher than 30 mm Hg, start oral or topical carbonic anhydrase inhibitors and local beta-blockers. Prescribe local broad-spectrum antibiotic eye ointment once a day for 1 week; longer for complicated cases. Topical prednisolone acetate 1%, 6 times per day for 10 days, 5 times per day for the next 10 days, and 4 times per day for the next 2 months. Then, the dose is tapered by 1 drop per day every 2 months. Thereafter, the dose is 1 drop per day for about 1 year.
  • Examine the patient every 15 days to look for a sign of graft rejection. Interrupted sutures are removed, starting 2-3 months postoperatively. Remove running sutures after 12 months. Selectively remove interrupted sutures until the astigmatism is less than 3 diopters. Suture removal occurs later in eyes with only interrupted sutures.

Cataract surgery in Fuchs endothelial dystrophy

If precautions are taken to protect the endothelium during surgery, most cases of confluent guttata, without corneal symptoms, do well with cataract and lens implant surgery.

No dietary restrictions are noted.

Advise the patient to avoid any kind of trauma to the eye. The eye may be cleaned with boiled and cooled wet cotton swabs. After a period of 2 weeks, the patient can take a brisk walk, watch television, and resume any visual task that the eye is capable of with or without refractive correction.