LASEK has more than 1 year of successful experience

The technique has all the advantages of painless recovery, fast return of visual acuity and lack of complications, according to its developer.

---The epithelium is detached with the short side of a hockey spatula.

ROVIGO, Italy — With more than 1 year’s experience since its first application, laser epithelial keratomileusis (LASEK) is seen as a reliable and effective refractive surgery technique, meeting increasing success both in Italy and abroad.

Now that the surgical instruments have been perfected and some aspects of the technique have been better defined, its inventor, Massimo Camellin, MD, feels confident that “LASEK is, to date, the best and safest way of correcting both myopia and hyperopia. Since I discovered it, I have used it and nothing else.”

The idea of LASEK originated from a series of coincidences and casual observations. The corneal grafts used for keratoplasty gave Dr. Camellin the first insight.

“The corneas I was using were preserved in culture fluid at room temperature,” he said. “I realized that, compared with corneas preserved at 5°, they did not require a time for re-epithelialization, as their original epithelium was still vital at the moment of transplantation and protected the graft right from the first day.”

The second observation came from the positive experience Dr. Camellin had with alcohol de-epithelialization in photorefractive keratectomy (PRK), as suggested by Dr. Carones at a refractive surgery meeting in Italy.

“Right from the beginning, the results of alcohol de-epithelialization were excellent, particularly regarding the quality of surface obtained and for the short time the epithelium took to reform after the procedure,” Dr. Camellin said.

The third element was the accidental breaking of a bottle of alcohol solution he used for the procedure.

“I asked the pharmacist to prepare me a new one, and noticed that the solution was not as effective as the previous one,” Dr. Camellin said. “The detachment of the epithelium, which, in those days, I used to throw away, was incomplete and difficult. Talking to the pharmacist, I discovered that, unlike the first one that contained distilled water plus alcohol, the second bottle contained physiologic solution plus alcohol. The mistake made by the pharmacist, who thought I was using the solution to clean surgical instruments, made me realize the importance of preparing a hypotonic solution to facilitate epithelial detachment.”

The final piece of the puzzle was the removal of a foreign body, trapped for more than a month under the corneal epithelium of a patient.

“When I removed it, I created a microflap of about 2 mm sealed on one side, which I then left to cover the ulcer,” Dr. Camellin said. “The day after, I was delighted to hear that the patient had experienced no pain in the hours following the operation. I gathered that alcohol de-epithelialization could be used in the same manner to create a large epithelial flap, and attempted this on my first patient. The perfect transparency and vitality of the flap in the days following the operation have persuaded me to carry on using this technique up to now.”

Technique and variations

---Epithelial flap healing in LASEK can take place in four ways. When the flap is healthy, the regrowth takes place both from the flap toward the limbus and vice versa. Visual recovery is fast and painless in about 70% of cases.

A pre-incision of the corneal epithelium is performed to circumscribe the flap area, leave a hinge of about 90° at the 12-o’clock position and allow the alcohol solution to penetrate under the flap.

“Initially, we used a trephine with a 70 mm blade,” Dr. Camellin said. “More recently, we have increased the size of the blade to 80 mm in 8-mm trephines, and to 90 mm in 9-mm trephines. The two sizes are needed for myopic and hyperopic treatment, respectively.” A blunt portion of the blade, of about 100° at the 12-o’clock position, protects the area of the hinge.

A rotation of about 10° is performed, repeating the maneuver two or three times and maintaining a constant pressure.

The trephine, which like all instruments for LASEK is manufactured by Janach (Como, Italy), can efficiently perform about 100 incisions. A saw-toothed version also is available for very thick epithelia.

A 20% alcohol solution (96% pure alcohol in injectable distilled water) is then instilled into the eye through a small silicone irrigator. Dr. Camellin recommends that plastic syringes should be avoided due to the risk of contamination by toxic monomers. The solution must be shaken before each operation.

The alcohol solution is collected in a special cone, with the double function of holding the eye still and avoiding undesired discharge of fluid. After 30 seconds, the surface is dried and rinsed thoroughly with balanced salt solution.

“Recently, we have introduced a final irrigation with antihistamine to reduce any initial release of histamine induced by the alcohol,” Dr. Camellin said.

As the pre-incision is not always perfect, an epithelial micro-hoe is used to complete it. If the epithelium is still too tight, fresh alcohol solution can be applied for 5 seconds before lifting the margins.

The epithelium is detached with the short side of a hockey spatula, making tiny movements almost perpendicular to the margin. The flap is then folded at the 12-o’clock position to keep it moist during the treatment and to prevent it from being sucked by the suction ring in lasers fitted with this device.

“The creation of an epithelial flap may be difficult for the first few times. Experience makes it easier, although the degree of difficulty may vary from patient to patient,” Dr. Camellin said.

Laser ablation and flap repositioning

---When the flap is poorly vital but the basal membrane adheres well to the stroma, the regrowth takes place from the periphery over the lamina lucida. The presence of epithelial cells on the flap slows down the growing process.

Before laser ablation, the longer side of the hockey spatula is passed over the stromal surface to remove any debris that is still there. If necessary, the exposed stromal area can be enlarged by slightly stripping the epithelium in the periphery. This maneuver has almost no delaying effect on the healing process, Dr. Camellin said.

“From my experience,” he said, “the laser should be set at lower values than those normally indicated, as the almost total absence of regression entails a higher correction than that obtained with PRK. In order to reduce the residual refractive error, it is advisable to reduce the preset values by 10% when treating myopia up to 10 D and by 20% for myopias between 10 D and 20 D. Overcorrection is thus avoided, and less tissue can be ablated for the same degree of correction. Higher corrections can, therefore, be carried out safely.”

If smoothing is performed, it is advisable to protect the flap with masking fluid. According to the surgeon, this makes it easier to reposition the epithelium in the following stage. As an alternative, the stromal surface can be irrigated before repositioning.

A soft contact lens is then applied. The lens must be sufficiently thick (about 100 mm), with a basic radius of 8.4 mm or 8.7 mm and a diameter of 14 mm to 14.4 mm.

“These parameters are important, as excessive mobility of the lens may cause tearing and loss of the hinge,” Dr. Camellin said. “To be well contained, the lens must be tightly secured.”

---A grayish appearance in some areas and embedded micro-bubbles are signs that the epithelial flap has completely lost vitality. Visual recovery is still fairly fast, as the flap protects the stroma and facilitates epithelial growth from the periphery under the lamina lucida.

“So far we have been using Precision UV lenses [Wesley Jessen, Chicago], where the basic radius is sized based on the preoperative corneal curvature of the patient — about 0.7 mm larger than the medium radius. Good results also have been obtained with ProTek Therapeutic Soft Lenses [CIBA Vision], with a basic radius of 8.9 mm, a diameter of 14.5 mm and center thickness of 45 mm,” he said.

Postoperatively, antibiotics and cortisone are administered for a few days. Mild cortisone treatment is continued for up to a month.

“The patient is examined the day after surgery to check on the position of the lens and on the general response of the eye,” Dr. Camellin said. “Inflammatory reactions very rarely occur. A discharge of alcohol during de-epithelialization may cause eyelid edema lasting for about 24 hours. A slight exfoliation of the flap may soil the lens. No other reaction has been observed.”

The lens should remain in place for 3 to 4 days to guarantee complete re-epithelialization. If the epithelium has not re-formed by that time, a new lens is fitted for 3 more days.

“It is up to the surgeon to decide on further appointments, as no adverse events occur after this stage,” Dr. Camellin said.

Flap healing

---In rare cases, the flap may be severely damaged by the stress of detachment. What remains of the epithelium should be folded and positioned under the lens, at the center of the cornea. In such conditions, the flap is no protection against postoperative pain.

Dr. Camellin observed that the flap healing process may take place in four different ways, depending on the vitality of the epithelium.

When the epithelial flap is vital and integral after surgery, the regrowth takes place both from the flap toward the limbus and vice versa (Figure 1). Visual recovery in this case is fast and completely painless in about 70% of cases.

When the flap is poorly vital but the basal membrane adheres well to the stroma, the regrowth takes place from the periphery over the lamina lucida (Figure 2). The presence of epithelial cells on the flap slows down the growing process. In some cases, a slightly opaque line may appear, as occasionally in PRK. The line is visible for some months, and progressively fades away afterward. Visual recovery is slower and there might be some pain.

A grayish appearance in some areas and embedded micro-bubbles are signs that the epithelial flap has completely lost vitality. Visual recovery is still fairly fast (about a week for 80% functional recovery), as the flap protects the stroma and facilitates epithelial growth from the periphery under the lamina lucida (Figure 3). There might be slight postoperative pain. In these cases, it is advisable to leave the lens in place for a few more days.

In rare cases, the flap may be severely damaged by the stress of detaching maneuvers. This is more common in patients who have worn soft contact lenses for long periods. What remains of the epithelium should be folded and positioned under the lens, at the center of the cornea, as the “feeder effect” of the cells on the surface guarantees a fairly fast recovery and return of visual acuity (Figure 4). Re-epithelialization is completed in 4 to 5 days. Obviously, in such conditions the flap is no protection against postoperative pain.

Results

---A fine subepithelial dotting was visible in 20% of cases, but no reticular or diffuse haze.

Dr. Camellin has treated a total of 249 patients with LASEK. Of these patients, 204 were myopic (mean 6.1 D ±4.2 standard deviation), 41 hyperopic or hyperopic astigmatic (mean 2.2 D ±2 standard deviation) and 29 were re-treated after PRK haze, radial keratotomy, keratoplasty or LASEK. The longest follow-up is 14 months.

Intraoperative flap management was easy in 60% of cases, average in 28% of cases and difficult in 12%. Difficulties were in all cases connected with the strong adherence of the epithelium to Bowman’s membrane.

Re-treatments were not included in these percentages, as flap management is inevitably difficult in all cases.

In re-treatments after LASEK, the flap was easily detachable within 3 months, almost as in a primary operation. “This confirms that the presence of the basal membrane reduces scar exuberance and excessive proliferation of new collagen,” Dr. Camellin said.

Postoperative pain appears to be limited, if any, to the first 24 hours after surgery. No pain was experienced by 44.4% of patients, some discomfort was reported by 41.8% and pain by 13.7%.

“Undoubtedly, postoperative pain is partly due to the contamination of the conjunctiva by the alcohol solution,” he said. “The irritation of the conjunctiva gives way to a series of inflammatory reactions. The use of antihistamine in postoperative medications has reduced the percentage of patients complaining of pain to 5.2%. We may deduce that there is an early release of histamine. By blocking it, we reduce the release of other transmitters at the same time,” he said.

Loss of the flap connected with loss of the lens was reported in 2.53% of cases.

“Recently, the use of a lens with narrower base radius [ProTek Therapeutic Soft Lenses; CIBA Vision] has dramatically reduced the occurrence of this complication,” Dr. Camellin said.

According to Dr. Camellin, the greatest advantage of LASEK is the absence of haze.

“The absence of neo-collagen production, regression and haze phenomena in LASEK is probably due to reduced apoptosis,” he said. “In fact, the basal membrane protects the keratocytes from oxidation, preventing the migration of keratocytes from deeper layers.”

A fine subepithelial dotting was visible in 20% of cases (Figure 6). “It may be a sign of regrowth of the junctions between epithelium and stroma, appearing about a month postoperatively and disappearing around month 3. However, reticulation or diffuse opacities have never been observed,” he said.

Almost 90% of patients achieve 80% of their preop best corrected visual acuity at day 10 after surgery.

“My results confirm what I thought from the beginning,” Dr. Camellin said. “LASEK has many advantages in comparison with both LASIK [laser in situ keratomileusis] and PRK. It eliminates the main drawbacks of PRK, such as postoperative pain, risk of infection, regression, haze and slow recovery. On the other hand, all the well-known complications related to the LASIK flap are avoided, with the additional advantage of being easier and less expensive.”

For Your Information:

• Massimo Camellin, MD, can be reached at Via Fiume 8, 45100 Rovigo, Italy; phone/fax: (39) 0425-411357; e-mail: cammas@tin.it. Dr. Camellin has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.

• All instruments for LASEK are produced by E. Janach srl, Via Borgovico 35, 22100 Como, Italy; (39) 031-574088; fax: (39) 031-572055; e-mail: janach@betacom.it.