**4. Advantages**

#### **4.1. DALK**

The advantages of performing DALK corneal transplants are [1] as follows:

**4.2. DSAEK/DMEK**

• less transurgical risks

**5. Surgical technique**

which will be described here.

**5.1. DALK**

• small incision

• lower immunologic rejection rate

on the right the same eye 12 months later.

• less sutures or absence of them

• less complications related to ocular surface

• preservation of the anatomic integrity of the cornea

• preservation of the corneal innervation

The advantages of performing endothelial transplants are [8] as follows:

**Figure 2.** Clinical photographs of an endothelial transplant. On the left a photograph taken at the end of the surgery and

Intraoperative OCT in Lamellar Corneal Transplants (DALK, DSAEK, DMEK)

http://dx.doi.org/10.5772/intechopen.79322

101

• visual acuity recovery is faster, more stable and more predictable (**Figure 2**)

Nowadays, due to its elevated success rate, the authors use the pachy-bubble technique,

The technique begins with a partial trepanation of 80% of the corneal thickness and an average diameter of 8 mm. Afterward, an ultrasound pachymeter is utilized to measure the corneal thickness in MXII, at a distance of 3 mm from the visual axis. The diamond scalpel is


**Figure 1.** Wound dehiscence in a patient with DALK surgery. The patient received an ocular trauma 1 month postsurgery and eight stitches broke, yet the Descemet remained intact without aqueous humor leakage.

Intraoperative OCT in Lamellar Corneal Transplants (DALK, DSAEK, DMEK) http://dx.doi.org/10.5772/intechopen.79322 101

**Figure 2.** Clinical photographs of an endothelial transplant. On the left a photograph taken at the end of the surgery and on the right the same eye 12 months later.

#### **4.2. DSAEK/DMEK**

• postsurgical bullous keratopathy

• traumatic endothelial dysfunction • iridocorneal endothelial syndrome

• no immunologic endothelial rejection

• higher resistance to traumatic injuries (**Figure 1**)

• extra-ocular procedure

• higher transurgical safety

• endothelium preservation

• better refractive stability

• less postsurgical use of steroids

• corneal transplant rejection

• posterior polymorphous corneal dystrophy

The advantages of performing DALK corneal transplants are [1] as follows:

**Figure 1.** Wound dehiscence in a patient with DALK surgery. The patient received an ocular trauma 1 month postsurgery

and eight stitches broke, yet the Descemet remained intact without aqueous humor leakage.

• Fuchs dystrophy

100 OCT - Applications in Ophthalmology

**4. Advantages**

**4.1. DALK**

The advantages of performing endothelial transplants are [8] as follows:


### **5. Surgical technique**

#### **5.1. DALK**

Nowadays, due to its elevated success rate, the authors use the pachy-bubble technique, which will be described here.

The technique begins with a partial trepanation of 80% of the corneal thickness and an average diameter of 8 mm. Afterward, an ultrasound pachymeter is utilized to measure the corneal thickness in MXII, at a distance of 3 mm from the visual axis. The diamond scalpel is calibrated for 90% of the pachymetric measurement and a 4-mm incision is performed in this area. Air is injected into the anterior chamber, which will help verify the formation of the big bubble. A specially designed cannula is inserted and moved through the pre-Descemet plane until the visual axis is reached. It is in this zone were air will be injected. Afterward, the stroma is perforated to reach the stroma-Descemet interphase, which is now full of air (**Figure 3**). The stroma is removed and the donor cornea (with no endothelium) is sutured with nylon 10–0.

• detritus, hemorrhage, vascularization, microbial infections and epithelial growth in the

Intraoperative OCT in Lamellar Corneal Transplants (DALK, DSAEK, DMEK)

http://dx.doi.org/10.5772/intechopen.79322

103

There are many variations to the original endothelial transplant DSAEK technique. The one

The donor cornea is prepared using a Moria microkeratome adapted to an artificial anterior chamber. The ideal thickness is between 90 and 120 μm. Afterward, the donor cornea is trep-

Once the donor tissue is obtained, surgery begins by inserting an anterior chamber maintainer. Trypan blue solution is inserted to the anterior chamber for better visualization of the Descemet membrane. A circular descemetorhexis is performed with a diameter of 8.25 mm. A 2-mm incision is done on the temporal limbus and a 4-mm incision on the nasal limbus. An iridotomy is performed on the meridian at six o´clock and the donor tissue is inserted through the nasal incision using a Busin glide or any other type of injector designed for this purpose. The temporal incision is used for the instrument used to help during the insertion of the donor tissue. Finally, the anterior chamber is filled with air for adequate fixation of the graft.

The most reported complication in endothelial transplants is the lack of adherence of the donor tissue to the recipient's stroma. The key to reducing the dislocation is a meticulous reconstruction of the wound (so that there is no leakage of aqueous humor) and complete removal of fluid from the interphase. Whenever a graft is dislocated, it can be accommodated once again with air injections; nevertheless, this may cause damage to the endothelial cells.

To obtain the donor tissue, the Blister technique is used, a technique developed by Eric Abdullayev (Manager of Clinical Development and Innovations at Lions Eye Institute for

• pupillary block glaucoma secondary to injected air in anterior chamber

• recurrence of the stromal corneal dystrophy

• Difficulty in re-epithelization

used by the authors is described here.

anated with an average diameter of 8.25 mm.

• lack of adherence of the donor tissue • foldings or tears in the donated tissue

• inverted positioning of the tissue

• pneumatic pupillary block

**5.3. DMEK**

The DSAEK procedure has some complications including:

• endothelial dysfunction secondary to surgical trauma

The DMEK technique used by the authors is described below.

interphase

**5.2. DSAEK**

It is important to mention that to achieve an adequate Descemet detachment, the air injection should be very deep, unfortunately leading to an increased perforation risk [2]. This step continues to be the most challenging part of the surgery.

If the injection of air is too superficial or if it remains in the medium stroma, it will usually disseminate laterally without detaching the Descemet and will give the cornea a diffuse-white appearance. When this happens, the surgeon must try to inject the air deeper or change to a manual dissection (layer by layer) technique, which frequently leads to perforation. This technique is a challenge in advanced keratoconus with a severe corneal thinning or scarring and has a reserved success rate when there are dense corneal opacities due to the bad depth visibility [6].

Some of the disadvantages of this type of transplant are its steep learning curve and its longer surgical time compared to a PK [1]. In many countries, including Mexico, this technique does not have a widespread use secondary to its difficulty and longer time requirements. Nowadays, even a skilled surgeon performs with a risk of perforation between 10 and 30% [10].

The DALK procedure has some complications including [1]:


**Figure 3.** Perforation of the corneal stroma in a DALK corneal transplant.


#### **5.2. DSAEK**

calibrated for 90% of the pachymetric measurement and a 4-mm incision is performed in this area. Air is injected into the anterior chamber, which will help verify the formation of the big bubble. A specially designed cannula is inserted and moved through the pre-Descemet plane until the visual axis is reached. It is in this zone were air will be injected. Afterward, the stroma is perforated to reach the stroma-Descemet interphase, which is now full of air (**Figure 3**). The stroma is removed and the donor cornea (with no endothelium) is sutured

It is important to mention that to achieve an adequate Descemet detachment, the air injection should be very deep, unfortunately leading to an increased perforation risk [2]. This step

If the injection of air is too superficial or if it remains in the medium stroma, it will usually disseminate laterally without detaching the Descemet and will give the cornea a diffuse-white appearance. When this happens, the surgeon must try to inject the air deeper or change to a manual dissection (layer by layer) technique, which frequently leads to perforation. This technique is a challenge in advanced keratoconus with a severe corneal thinning or scarring and has a reserved success rate when there are dense corneal opacities due to the bad depth

Some of the disadvantages of this type of transplant are its steep learning curve and its longer surgical time compared to a PK [1]. In many countries, including Mexico, this technique does not have a widespread use secondary to its difficulty and longer time requirements. Nowadays,

even a skilled surgeon performs with a risk of perforation between 10 and 30% [10].

continues to be the most challenging part of the surgery.

The DALK procedure has some complications including [1]:

**Figure 3.** Perforation of the corneal stroma in a DALK corneal transplant.

with nylon 10–0.

102 OCT - Applications in Ophthalmology

visibility [6].

• Descemet membrane rupture

• loss of endothelial cells secondary to air/gas

• interphase opacities or irregularities

• double anterior chamber

There are many variations to the original endothelial transplant DSAEK technique. The one used by the authors is described here.

The donor cornea is prepared using a Moria microkeratome adapted to an artificial anterior chamber. The ideal thickness is between 90 and 120 μm. Afterward, the donor cornea is trepanated with an average diameter of 8.25 mm.

Once the donor tissue is obtained, surgery begins by inserting an anterior chamber maintainer. Trypan blue solution is inserted to the anterior chamber for better visualization of the Descemet membrane. A circular descemetorhexis is performed with a diameter of 8.25 mm. A 2-mm incision is done on the temporal limbus and a 4-mm incision on the nasal limbus. An iridotomy is performed on the meridian at six o´clock and the donor tissue is inserted through the nasal incision using a Busin glide or any other type of injector designed for this purpose. The temporal incision is used for the instrument used to help during the insertion of the donor tissue. Finally, the anterior chamber is filled with air for adequate fixation of the graft.

The DSAEK procedure has some complications including:


The most reported complication in endothelial transplants is the lack of adherence of the donor tissue to the recipient's stroma. The key to reducing the dislocation is a meticulous reconstruction of the wound (so that there is no leakage of aqueous humor) and complete removal of fluid from the interphase. Whenever a graft is dislocated, it can be accommodated once again with air injections; nevertheless, this may cause damage to the endothelial cells.

#### **5.3. DMEK**

The DMEK technique used by the authors is described below.

To obtain the donor tissue, the Blister technique is used, a technique developed by Eric Abdullayev (Manager of Clinical Development and Innovations at Lions Eye Institute for

830 and 1325 nm. OCT has revolutionized clinical ophthalmology, and its development continues providing opportunities for a better diagnosis and even management of eye diseases. Originally introduced in the 1990´s at the Massachusetts Institute of Technology in 1991 as a technique for noninvasive transverse imaging of biological systems, the image of the retina was the first application of this technology [11]. OCT devices have undergone modifications in their original technique to see and measure anterior segment structures such as the cornea, iris, and the lens [12]. In 1994, Izatt described the use of OCT for the anterior segment with a resolution close to histological level [13]. Since then, it has been used for the diagnosis and

Intraoperative OCT in Lamellar Corneal Transplants (DALK, DSAEK, DMEK)

http://dx.doi.org/10.5772/intechopen.79322

105

**Figure 5.** OPMI LUMERA & RESCAN 700 microscope, where OCT images can be observed in real time.

**Figure 6.** OPMI LUMERA & RESCAN 700 microscope, OCT images can be appreciated for all members of the surgical

team.

**Figure 4.** Blister technique for the isolation of corneal Descemet-endothelium prior to a DMEK surgery.

Transplant and Research, Tampa, Florida, USA). In this technique, balanced saline solution is injected to achieve separation of the Descemet membrane (**Figure 4**). Currently, it is possible to get the tissue prepared and preloaded by the staff of some eye banks, which facilitates the procedure and eliminates the risks of tissue preparation in the operating room.

Once the donor tissue is obtained, surgery is performed on the recipient, initiating with the introduction of trypan blue to improve Descemet visualization, then the circular descemetorhexis of an average of 8.25 mm is performed. The Descemet can be extracted using the irrigation-aspiration piece of the phacoemulsification equipment, through a previously performed 3 mm incision. An iridectomy is performed in MVI, and the donor tissue is introduced and unfolded with delicate hydraulic and pressure-counter-pressure maneuvers, finally introducing the air/gas in the anterior chamber once the correct unfolding of the graft has been ensured. The eye must be completely sealed with or without sutures.

The DMEK procedure has some complications including:


Currently, the number of surgeons performing DMEK is on the rise because of its better visual acuity results when compared to DSAEK.
