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Non-freeze myopic keratomileusis: a four-year experience
Correspondence Sir, Non-freeze myopic keratomileusis: a four-year experience
We wish to report our experience with non-freeze myopic keratomileusis of which we have had four years experience. Non-freeze myopic keratomileusis is a form of auto-lamellar keratoplasty which re-shapes the cornea. This planar lamellar refractive keratoplasty procedure (PLRK) was originally described by Swinger et al. [1] in order to overcome some of the disadvantages of the Barraquer freezing technique [2-4]. We felt it would be useful to repeat a series of 100 myopic eyes which were consecutively operated by one of us using a BKS 1000 set (Eyetech M.V.A. A.G. Balzers Liechtenstein) during a four-year period. Thirty-five women (58 eyes) and 26 males (42 eyes) were treated by this procedure. They were divisible into four refraction groups [5]: A, -6.25 to -10 D, 28 eyes; B, -10.12 to -15 D, 34 eyes; C, -15.12 to -20 D, 21 eyes; D, -20.12 to -28 D, 17 eyes. The refractive and visual results are summarized in Table 1. The mean follow-up period was 544 days with a range of 3 months to 4 years. It was only possible to follow up 32 eyes for longer than 2 years as patient compliance in the study was poor. Because of the finite number of dies for corneal reshaping, it is not possible to correct continuously all degrees of myopia with PLRK. Thus we considered the mean percentage of achieved spherical correction, which is the ratio between the obtained and the desired correction. This ratio after a 6-month period was 90.45% in group A, 81.62% in group B, 63.68% in group C and 74.83% in group D. The mean overall preoparative astigmatism was 1.14 D ± 0.85 D. Postoperatively, it was 2.19 D ± 1.68 D after 6 months and often irregular, but did decrease with re-operations.
Twelve patients were re-operated after a 6-month period when five radial keratotomies were performed to improve previous undercorrection: T -cut or transverse keratotomy in three cases, lenticule reshaping in three cases for serious undercorrection and 1 myopic homoplastic keratomileusis to address an overcorrection. All the patients treated suffered from high myopia with contraindications to contact lens or glasses wear. There was a preponderance of female patients. The postoperative refraction showed a dramatic decrease of myopia but with time there was some regression which was variable from patient to patient. There was no strict relationship between the refractive and visual result. In all cases the postoperative uncorrected visual acuity improvement was dramatic and rapid, being appreciated 1 day post operation. We believe as a result of our experience that myopic keratomileusis may be considered as a safe procedure, but the difficulty of accurately predicting outcome in an individual eye is common to this as to all refractive procedures. Non-freeze myopic keratomileusis still remains an interesting alternative treatment for the management of high myopia.
REFERENCES 1 CA Swinger, J Krumeich, D Cassiday. Planar lamellar refractive keratoplasty. J. Refract. Surg., 1986; 2: 17-24. 2 JI Barraquer, E Viteri. Results of myopic keratomileusis, J. Refract. Surg., 1987; 3: 98-101. 3 T Yamaguchi, MG Friedlander, T Kimura, SB Koenig, HE Kaufmann. The ultrastructure of well-healed lenticules in keratomileusis. Ophthalmology, 1983; 90: 1495-1506. 4 EZ Zavala, J Krumeich, PS Binder. Clinical pathology of nonfreeze lamellar refractive keratoplasty. Cornea, 1987; 3: 223230. 5 GO Waring III. Conventional standards for reporting results of refractive surgery. Refractive and Corneal Surgery, 1989; 5: 285-287.
L. Laroche, J.C. Thenot, J.P. Nordmann, G. Montefiore, P. Denis and H. Saraux Hopital St Antoine, 184 rue St Antoine, 75571 Paris, Cedex 12, France
Table 1 Main refractive and visual results Preop Overall 3M 6M 12M 2Y+ -14.5 -2.91 -3.27 Mean S.E. -3.88 -4.58 Mean nc VA 0.27 (±0.13) 0.33 (±0.18) 0.48 (±0.21) 0.05 0.57 (±0.20) 0.46 (±0.18) 0.62 (±0.24) Mean best c VA 0.38 ( ±0.13) 0.54 (±0.19) 0.57 (±0.25) Abbreviations: SE, Spherical equivalent (in D); nc VA, non corrected visual acuity; c VA, corrected visual acuity; M, month; 2Y +, 2 years and more.
0955-3681/92/020123+01 $03.00/0 © 1992 Bailliere Tindall
Eur J Implant Ref Surg, Vol 4, June 1992
We wish to report our experience with non-freeze myopic keratomileusis of which we have had four years experience. Non-freeze myopic keratomileusis is a form of auto-lamellar keratoplasty which re-shapes the cornea. This planar lamellar refractive keratoplasty procedure (PLRK) was originally described by Swinger et al. [1] in order to overcome some of the disadvantages of the Barraquer freezing technique [2-4]. We felt it would be useful to repeat a series of 100 myopic eyes which were consecutively operated by one of us using a BKS 1000 set (Eyetech M.V.A. A.G. Balzers Liechtenstein) during a four-year period. Thirty-five women (58 eyes) and 26 males (42 eyes) were treated by this procedure. They were divisible into four refraction groups [5]: A, -6.25 to -10 D, 28 eyes; B, -10.12 to -15 D, 34 eyes; C, -15.12 to -20 D, 21 eyes; D, -20.12 to -28 D, 17 eyes. The refractive and visual results are summarized in Table 1. The mean follow-up period was 544 days with a range of 3 months to 4 years. It was only possible to follow up 32 eyes for longer than 2 years as patient compliance in the study was poor. Because of the finite number of dies for corneal reshaping, it is not possible to correct continuously all degrees of myopia with PLRK. Thus we considered the mean percentage of achieved spherical correction, which is the ratio between the obtained and the desired correction. This ratio after a 6-month period was 90.45% in group A, 81.62% in group B, 63.68% in group C and 74.83% in group D. The mean overall preoparative astigmatism was 1.14 D ± 0.85 D. Postoperatively, it was 2.19 D ± 1.68 D after 6 months and often irregular, but did decrease with re-operations.
Twelve patients were re-operated after a 6-month period when five radial keratotomies were performed to improve previous undercorrection: T -cut or transverse keratotomy in three cases, lenticule reshaping in three cases for serious undercorrection and 1 myopic homoplastic keratomileusis to address an overcorrection. All the patients treated suffered from high myopia with contraindications to contact lens or glasses wear. There was a preponderance of female patients. The postoperative refraction showed a dramatic decrease of myopia but with time there was some regression which was variable from patient to patient. There was no strict relationship between the refractive and visual result. In all cases the postoperative uncorrected visual acuity improvement was dramatic and rapid, being appreciated 1 day post operation. We believe as a result of our experience that myopic keratomileusis may be considered as a safe procedure, but the difficulty of accurately predicting outcome in an individual eye is common to this as to all refractive procedures. Non-freeze myopic keratomileusis still remains an interesting alternative treatment for the management of high myopia.
REFERENCES 1 CA Swinger, J Krumeich, D Cassiday. Planar lamellar refractive keratoplasty. J. Refract. Surg., 1986; 2: 17-24. 2 JI Barraquer, E Viteri. Results of myopic keratomileusis, J. Refract. Surg., 1987; 3: 98-101. 3 T Yamaguchi, MG Friedlander, T Kimura, SB Koenig, HE Kaufmann. The ultrastructure of well-healed lenticules in keratomileusis. Ophthalmology, 1983; 90: 1495-1506. 4 EZ Zavala, J Krumeich, PS Binder. Clinical pathology of nonfreeze lamellar refractive keratoplasty. Cornea, 1987; 3: 223230. 5 GO Waring III. Conventional standards for reporting results of refractive surgery. Refractive and Corneal Surgery, 1989; 5: 285-287.
L. Laroche, J.C. Thenot, J.P. Nordmann, G. Montefiore, P. Denis and H. Saraux Hopital St Antoine, 184 rue St Antoine, 75571 Paris, Cedex 12, France
Table 1 Main refractive and visual results Preop Overall 3M 6M 12M 2Y+ -14.5 -2.91 -3.27 Mean S.E. -3.88 -4.58 Mean nc VA 0.27 (±0.13) 0.33 (±0.18) 0.48 (±0.21) 0.05 0.57 (±0.20) 0.46 (±0.18) 0.62 (±0.24) Mean best c VA 0.38 ( ±0.13) 0.54 (±0.19) 0.57 (±0.25) Abbreviations: SE, Spherical equivalent (in D); nc VA, non corrected visual acuity; c VA, corrected visual acuity; M, month; 2Y +, 2 years and more.
0955-3681/92/020123+01 $03.00/0 © 1992 Bailliere Tindall
Eur J Implant Ref Surg, Vol 4, June 1992