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Camellin LASEK Technique

Massimo Camellin, MD

Sekal Rovigo Microsurgery

Rovigo, Italy

INTRODUCTION

After a period of using photorefractive keratectomy (PRK) plus alcoholic disepithelization, the Camellin laser subepithelial keratomileusis (LASEK) technique was born in 1998 (1–8). Observing how easy it was to detach an epithelium while leaving it intact, repositioning it over the treated stroma was attempted, and after that first encouraging experience, the technique was consolidated with the use of instruments that have the purpose of preserving flap integrity despite its adherence. In this chapter, we will explain the main steps of the procedure and include a brief description of the necessary instruments.

Epithelial Precut

This first step, initially proposed only to delineate the area to be detached, showed greater importance over time as the precut allowed alcohol to flow under the epithelium more easily. The instrument used is a microtrephine. The sharp edge of the blade is from 80 to 90 microns deep and occupies 270 degrees of the entire circumference, leaving an un-cut hinge of 90 degrees at the 12 o’clock position. (Fig. 1) (E.Janach Sr., L.Via Borgo Vico

35Como, Italy).

The blade can be smooth or sawlike, with the latter being more efficient in thick

epithelium. The instrument must be pressed strongly to avoid too much superficial trephination. To ensure that the cut is as deep as possible, the trephine must be rotated for 10 degrees two or three times. It is important to remember to hold the handle always with the right hand and position it at 9 o’clock, even in left eyes (Fig. 2).

Alcohol Solution

The detaching solution can be composed of balanced salt solution (BSS) (80%) plus pure alcohol (20%) or distilled water (80%) plus pure alcohol (20%). Distilled solution plus alcohol showed a more powerful effect but had more toxic consequences for epithelial viability. We suggest, however, that one should continue to use this latter solution at least until practice improves one’s flap construction technique. The solution has to be prepared

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Figure 2 Microtrephine rotation whilst cutting.

every hour using a glass syringe because the rubber in a plastic one could react with the alcohol leaving toxic monomers. The solution is shaken before every treatment.

We throw away the first drops, spilling them before injecting the solution into a well to be sure the solution has the right concentration of alcohol. The solution can be heated to 32 degrees Celsius. Doing so can reduce the time that it must be left in the well. We usually leave the solution inside the well for 20 seconds.

The Well

This instrument looks like a round radial keratotomy marker but the significant difference is that it consists of a double edge for increasing eye stability during alcohol exposure (Fig. 3). Additionally, the double edge allows better control over leakage of the solution. The leakage of the alcohol solution is thought to be responsible for the pain in the early post-operative period. To avoid this problem, it is useful to accurately dry the well with a cotton sponge before taking away the instrument. The well can be filled with diclofenac and left for 5 seconds before drying. This procedure greatly reduces the possibility of alcohol contamination over the conjuntiva and minimize postoperative pain.

Edge Detachment

The maneuver for detaching the edge has two functions; the first is to enhance the precut and the second is to check the mobility of the flap. In the case of a strongly adherent flap, additional drops may be placed for 10 seconds after having created a gap in the epithelium. The gap allows the new solution to flow more easily under the epithelium.

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Figure 4 Micro-hoe for detaching epithelium (Janach).

Flap Sliding

An easy flap (usually found in 60% of eyes) can be separated by simply dragging it towards the 12 o’clock position (Fig. 5). We believe the technique has to be performed in all cases even in those flaps that are more difficult to detach. If the flap is slightly adherent to the stroma, a bow dissector can be used. This is performed by leveling the cornea like a microkeratome while sliding with gently oscillatory movements (Fig. 6).

The degree of difficulty increases when the epithelium is strongly attached as in reoperations or in particular patients (more frequent in dark eyes and long term soft lens

LASEK, PRK, and excimer laser stromal surface ablation 90

wearers). If, despite new alcohol application, resistance seems strong, we have to use the hockey spatula, which is held vertically and moved with small but precise movements.

Figure 5 Dragging epithelium in

LASEK (easy flap).

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Figure 6 Bow dissector in medium adherent epithelium (Janach).

The more attached the flap, the stronger the pressure needed to detach it without tearing. A limbal double-edged ring helps keep the eye firm during these maneuvers (Fig. 7).

PRK

This phase only needs a check for the right diameter of the flap compared to the treatment that is going to be performed. Attention must be paid to any suction ring device that some types of laser have because these can vacuum the flap.

Flap Re-positioning

A drop of BSS has to be instilled over the stroma to make re-positioning easy. Two rounded spatulas are useful for gently moving the epithelium. A soft contact lens is fitted and compressed with a flap applanator allowing water under epithelium to get out (Fig. 8). The choice of the lens must take into account the preoperative curvature and the flap integrity. The recommendation is to use a steeper lens in case of a small hinge, torn flap, and in a hyperopic treatment.

Lens Removal

The lens must be left in place for at least 4 days. In our opinion, if the lens does not cause discomfort it should be left for 6 to 7 days to allow the epithelium to become thicker and

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more attached. A possible reason why the lens may be removed early is if it causes discomfort because of debris or tightness.

Figure 7 (A-D) How the flap has to be managed to have an intact hinge at the end of the dissection. The sequence demonstrated and direction of movements with a hockey spatula in hard attached epithelia is demonstrated using arrows.

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Figure 8 Johnston applanator (Rhein medical) used to compress the flap (always to be used over a soft lens).

CONCLUSIONS

LASEK is a relatively simple, safe, and effective surgical technique. Attention to surgical detail may allow for a rapid learning curve. Almost 60% of the flaps are easy to detach and in these cases using all the aforementioned steps may not be imperative. For the cases in which flap elevation is more difficult, the full feasibility of the technique needs little effort to follow, and in so doing, 90% of the flaps become wellmanaged.

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REFERENCES

1.Camellin M. LASEK: nuova tecnica di chirurgia refrattiva mediante laser ad eccimeri. Viscochirurgia 1998(3); Vol XIII:39–43.

2.Camellin M. LASEK. CDROM, Editore Fabiano, 0, 1999.

3.Cimberle M, Camellin M. LASEK may offer the advantages of both LASIK and PRK. Ocular Surgery News International; 1999(3):14–15.

4.Camellin M. LASEK. Operative techniques in cataract and refractive surgery. In: Elander R, Ed. Vol. 3, 2000:98–108.

5.Cimerle M, Camellin M. LASEK technique promising after 1 year of experience. Ocular Surgery News 2000(14):14–17.

6.Camellin M. La LASEK Chrirurgia Refrattiva Principi e Tecniche. Fabiano Editore 2000: 403– 411.

7.Angelucci C, Camellin M. LASEK vs. LASIK: New procedure may offer fewer risks. Eye World 2001; 6:13–41.

8.Cimerle M, Camellin M. LASEK is easier than LASIK, it is less painful than PRK and it allows for wider range of correction than both. It also prevents haze more effectively. Ocular Surgery News 2001; 19:46–47.