Nd:YAG laser in the treatment of recurrent interface epithelial ingrowth after laser in situ keratomileusis

Título

Nd:YAG laser in the treatment of recurrent interface epithelial ingrowth after laser in situ keratomileusis

Autor

Martín J. Arroyo
Christopher J. Rapuano
Jagadesh C. Reddy

Fecha

Septiembre 2014

Lugar de Realización

Cornea Service, Wills Eye Institute, Philadelphia, Estados Unidos

Correspondencia

cjrapuano@willseye.org

Texto

Oftalmol Clin Exp 2014; 7(3): 93-100

Reporte de caso

Nd:YAG laser in the treatment of recurrent interface epithelial ingrowth after laser in situ keratomileusis

Martín J. Arroyo, Christopher J. Rapuano y Jagadesh C. Reddy

Cornea Service, Wills Eye Institute, Philadelphia, Estados Unidos

Abstract
Purpose: To report a case of recurrent interface epithelial ingrowth after laser in situ keratomileusis (LASIK) treated with Nd:YAG laser.
Method: A 59-year-old female presented to our service with blurred vision in both eyes (OU), for the preceding 6 months. She had a history of LASIK OU 12 years prior in 1998, with enhancements OU 6 months after primary surgery. In addition, she had a history of surgical intervention for epithelial ingrowth twice in each eye in 2008. She was diagnosed with significant interface epithelial ingrowth in the left eye. All potential options were discussed in detail with the patient. After consideration, she underwent 3 sessions of Nd:YAG laser treatments in the left eye.
Results: The patient was followed up for 2 years after the treatment with Nd:YAG laser in the left eye. Slit lamp biomicroscopy revealed elimination of the epithelial ingrowth.
Conclusion: Epithelial ingrowth after LASIK is not a rare complication in a referral cornea practice. Nd:- YAG laser should be considered as a potential, minimally invasive therapeutic option to treat interface epithelial ingrowth after LASIK.
Keywords: LASIK, epithelial ingrowth, laser in situ keratomileusis, complications, Nd:YAG laser.
No author has a financial or proprietary interest in any material or method mentioned.

Uso del láser Nd:YAG para el tratamiento del crecimiento epitelial recurrente en la interfase luego de la queratomileusis in situ con láser

Resumen
Objetivo: Descripción de un caso de crecimiento epitelial recurrente en la interfase luego del procedimiento de queratomileusis in situ con láser (LASIK, por sus siglas en inglés) tratado con láser Nd:YAG.
Método: Paciente de 59 años de edad de sexo femenino atendida en nuestro servicio que se presentó con visión borrosa de seis meses de evolución en ambos ojos (AO). Sus antecedentes fueron: LASIK en AO 12 años antes en 1998, con retoques en AO 6 meses luego de la primera cirugía. Además, la paciente se sometió a dos intervenciones para el tratamiento de su crecimiento epitelial en cada ojo en 2008. El diagnóstico fue crecimiento epitelial significativo en la interfase en el ojo izquierdo. Se le explicaron todas las opciones potenciales en detalle y luego de considerarlas, se le realizaron tres sesiones de láser Nd:Yag en el ojo izquierdo.
Resultados: La paciente tuvo un seguimiento de 2 años posteriores al tratamiento con láser Nd:Yag del ojo izquierdo. En el examen biomicroscópico con lámpara de hendidura se comprobó la eliminación del crecimiento epitelial.
Conclusión: El crecimiento epitelial posterior a la cirugía LASIK es bastante común en los consultorios especializados en córnea. El procedimiento con láser Nd:Yag debería ser considerado una opción terapéutica mínimamente invasiva para el tratamiento del crecimiento epitelial de la interfase luego del LASIK.
Palabras clave: LASIK, crecimiento epitelial, queratomileusis in situ con láser, complicaciones, láser Nd:-Yag.

Uso do laser Nd: YAG para o tratamento do crescimento epitelial recorrente na interfase logo da ceratomileusis in situ com laser

Resumo
Objetivo: Descrição de um caso de crescimento epitelial recorrente na interfase logo do procedimento de ceratomileusis in situ com laser (LASIK, pelas suas siglas em inglês) tratado com laser Nd: YAG.
Método: Paciente de 59 anos de idade de sexo feminino atendida em nosso serviço, quem se apresentou com visão turva de seis meses de evolução em ambos os olhos (AO). Seus antecedentes foram: LASIK em AO, 12 anos antes, no ano 1998, com retoques em AO 6 meses depois da primeira cirurgia. Além disso,a paciente foi submetida a duas intervenções para o tratamento do crescimento epitelial em cada um dos olhos no ano 2008. O diagnóstico foi crescimento epitelial significativo na interfase no olho esquerdo.
Foram explicadas para a paciente todas as potenciais opções em detalhe e, logo de considerar todas elas, serealizaram três sessões de laser Nd:Yag no olho esquerdo.
Resultados: A paciente teve um seguimento de dois anos depois do tratamento com laser Nd:Yag do olho esquerdo. No exame biomicroscópio com lâmpada de fenda se comprovou a eliminação do crescimento epitelial.
Conclusão: O crescimento epitelial posterior á cirurgia LASIK é bastante comum nos consultórios especializados em córnea. O procedimento com laser Nd:Yag deveria ser considerado como uma opção terapêutica minimamente invasiva para o tratamento do crescimento epitelial da interfase logo do LASIK.
Palavras chave: LASIK, crescimento epitelial, ceratomileusis in situ com laser, complicações, laser Nd:Yag.

Recibido: 21 de mayo de 2014.
Aceptado: 30 de mayo de 2014.
Autor responsable: Dr. Christopher J. Rapuano
Cornea Service Wills Eye Institute
840 Walnut Street, Suite 920
Philadelphia, Estados Unidos 19107
Tel. 1-215-928-3180
cjrapuano@willseye.org

Introduction

Rapid visual recovery and minimal postopera- tive discomfort after laser-assisted in situ keratomileusis (LASIK) have popularized the procedu- re among corneal refractive surgeries in last two decades. LASIK’s advantage over other corneal refractive procedures such as surface ablation are due to the flap, but the flap is occasionally asso- ciated with intraoperative problems like button- hole, shredded flap, partial flap, free cap, thin flap and postoperative issues such as flap dislocation and epithelial ingrowth.
Epithelial ingrowth is an important complication after LASIK and depending on severity is associated with decreased visual acuity due to irregular astigmatism, scarring and even flap necrosis1. Treatment of epithelial ingrowth is often based on severity as proposed by Probst and Matchat2. There are a variety of methods to manage epithelial ingrowth including observation1, 3, flap lift and scrape4, adjuvant methods with sutures or tissue glue for proper apposition of the flap5, alcohol for destroying the epithelial cells6, 28, 29, excimer laser phototherapeutic keratectomy7, amniotic membrane as a pressure patch8, and most recently Neodymium:Yytrium–Aluminum– gar- net (Nd:YAG) laser treatment9.
The Nd:YAG laser (wavelength -1064 nm) produces short individual pulses of focused in- frared light. The effect of Nd:YAG laser is by a nonlinear absorption process that causes plasma formation by strong heating, generation of cavi- tation bubbles and acoustic transients. The ener- gy contained within a single short pulse results in plasma formation giving rise to small vacuoles that join together to produce large vacuole. This creates an acoustic wave that disrupts nearby tissue10-12.
We describe a case of successful management of recurrent epithelial ingrowth using Nd:YAG laser.

Case report

A 59-year-old female with a systemic history of diabetes type 2 was referred to the Wills Cor- nea Service with the chief complaint of decreased vision in both eyes, the left being worse than the right. She underwent LASIK at another institution 12 years prior to the visit, in 1998. Flap lift enhancements were done in both eyes (OU) 6 months after the primary surgery, and epithelial ingrowth removal was performed twice in each eye between 3 and 6 months before her visit at Wills in 2008. There were no details of the pre- vious surgeries, but the patient’s records revealed that when the LASIK flap of left eye (OS) was lif- ted for removal of epithelial ingrowth, it came off completely (free cap) during the surgery. It was replaced and covered with a bandage soft contact lens.
On presentation to our Service, the uncorrected visual acuity (UCVA) was 20/40 in the right eye (OD) and 20/30 in the OS. On examination the patient had dry eyes with silicone plugs in OU in all four puncta. In OS, there was significant epithelial ingrowth superiorly encroaching on the visual axis (fig. 1a). There was also a small de- gree of epithelial ingrowth noted peripherally at 1 and 9 o’clock in the OD. She had grade I nuclear sclerosis in OU. The topography showed mild irregular astigmatism in the OS (fig. 3). As her vision was fairly good, the ingrowth was paracentral, she had undergone 2 previous unsuccessful manual removals of the epithelial ingrowth and had a history of a free LASIK cap, the advantages and disadvantages of attempting to treat the epithelial ingrowth in OS with a Nd:YAG laser were discussed in detail with the patient, who agreed to proceed.
After topical anesthesia, an Abraham YAG capsulotomy contact lens was placed on the left eye. Using the slit lamp mounted Nd:YAG laser (Co- herent Medical Group, Taracan Pty Ltd, Adelai- de, S.A 5000) laser shots were focused on the epi- thelial ingrowth, starting in the center of the area of epithelial ingrowth. The power was adjusted to the minimal amount to form bubbles (average 0.7 mJ) (fig. 2). At the margin of each bubble, new spots of laser were shot until the entire area of the epithelial ingrowth was treated.
Three sessions of Nd:YAG laser were perfor- med at approximately 1 month intervals between each in the OS. Approximately 25 laser spots were performed at each session. After each treatment prednisolone acetate 1% was used four times per day for one week, twice a day for one week, once a day for one week, and then stopped. After each session of Nd:YAG laser treatment there was decrease in size of the epithelial ingrowth and the borders became well defined (figs. 1b, 1c). After the third session of Nd:YAG laser treatment, the epithelial ingrowth almost completely disappea- red. At 2 years after Nd:YAG laser treatment the BSCVA was 20/30 (-2.25+1.75Dx160º) OS. Slit lamp biomicroscopy showed no evidence of epithelial ingrowth but only minimal scarring in the area of previous epithelial ingrowth (fig.1d). Corneal topography (Atlas System, model 995, Carl Zeiss Meditec, Dublin, CA). Before and at 2 months after 3rd session of Nd:YAG la- ser treatment were 40.75D, 38.87D and 40.62D, 40.00D respectively showing a mild change in as- tigmatism (fig. 3a, 3b).

Discussion

Some degreee of epithelial ingrowth is seen in 90% of cases within first 2 months after LASIK13. The incidence of epithelial ingrowth varies from 0-20%14-17 but can be as high as 32% in cases of enhancements18. Chan et al have shown that the high incidence of epithelial ingrowth in enhancements may be due to trauma caused while lifting or manipulating the flap19. Epithelial ingrowth occurs as a result of direct implantation of epithelial cells during surgery or postoperative migration of surface epithelial cells under the edge of the flap20.
Several risk factors have been reported that may lead to the development of epithelial ingrowth. These include epithelial basement membrane dystrophy, previous epithelial ingrowth in the f llow eye, hyperopic LASIK correction, flap instability, intraoperative epithelial defects, recurrent corneal erosions, diabetes mellitus with epithelial keratopathy, decentered flaps, trauma, increasing age, the surgeon’s experience, the use of bandage contact lens during enhancements, the type of excimer laser system, and a thinner LASIK flap9,13, 19-25.
Clinically, epithelial ingrowth may present as epithelial pearls in the interface, a sheet of confluent opacity, a fibrotic demarcation line or melting of the flap26-27. Epithelial ingrowth is usually treated based on clinical severity. Treatment is advocated in cases where ingrowth has approached greater than 1-2 mm from the flap edge, presence of visual symptoms from irregular astigmatism, thickening of the flap, flap melting or erosion due to epithelial ingrowth. Initially epithelial ingrowth was treated by lifting the flap and scraping the bed and the posterior surface of the flap but it was associated with clinical significant recurrence in 23% of cases [include my paper, ref 1, here and give a range of success rates]13. Later adjuvant treatment like 50% ethanol and 70% isopropyl alcohol were used but were associated with recurrence, diffuse lamellar keratitis or melting of the flap6, 28-29. Rojas et al15 and Narvaez et al5 have tried combination treatment by lifting the flap, scraping the bed, flap and then either suturing the flap or application of fibrin glue with good success. Excimer laser PTK was used by Fager- holm et al to treat primary as well as recurrent epithelial ingrowth with good success except for development of cystic ingrowth which required surgical intervention7.


Ayala MJ et al reported treating thirty eyes with Nd: YAG laser for clinically significant epi- thelial ingrowth after LASIK9. It was noted that the opacities caused by the epithelial ingrowth disappeared in eighty percent of the cases with the Nd:YAG laser treatment. In forty percent of the cases, two or more sessions of Nd:YAG laser treatment were necessary to eliminate the epithe- lial ingrowth areas entirely. In sixty percent of the cases, visual acuity improved by one or more lines of vision and the treatment, symptoms such as glare and halos improved in all cases. The intensity of the laser treatment was adjusted in each case and was focused on the epithelial ingrowth areas. There were no complications reported.

The primary surgical mechanism of Nd: YAG laser is tissue evaporation by the laser plasma, whe- reas the collateral damage from single laser pulses is mainly caused by the cavitation and jet formation. The damage range after a 4-mJ laser pulse is 0.8 mm which is slightly larger than the correspon- ding cavitation bubble radius30. The amount of laser used for removal of ingrowth is very less and hence there is less chance for the occurrence of any complications due to Nd: YAG laser.
Keeping in mind our previous experience, published literature and the patient having recurrent epithelial ingrowth and a free cap in OS, we decided not to lift the flap and used Nd:YAG laser treatment due to its non-invasive nature. In our case, the epithelial ingrowth resolved and the vision remained stable. The treatment of epithelial ingrowth with Nd:YAG laser is a straightforward technique, which was well tolerated by the patient. However, as in this case multiple treatments may be required.

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