屈折手術学会誌 Vol22 2006年5月 429−430P
（英文より要訳とコメント） |
編集室経由でイスラエルのリフシィツ博士と、ギリシャのキミオニス博士との書簡の交換が披露されている。「軽度近視のレーシック後発症の両側性角膜拡張症」についてである。
前者が前回の書簡に角膜解析図を加え、後者の批判に答えた内容となっている。
タイトルの報告に対して、後者は角膜解析図の提示が無いことや、マイクロケラトームの精度からすると、フラップ作成の厚さは不正確で、100〜250マイクロンの大きな巾があるので、この様な報告をするのは不適当であると主張する。前者は、角膜解析図に角膜拡張症を示唆するフルステサインが認められず、フラップ作成に用いたニデック社製2000マイクロケラトームなら、フラップ厚を160μに設定しても、せいぜい±20〜22μの誤差であり、角膜拡張症を合併させてしまうことはないはずであり、それにもかかわらず、合併症がおきた事が問題であると反論している。
リフシィツ博士は、近視矯正RK手術時代より、ロシアのフィヨドロフ博士の弟子であり、友人であった。一方のキミオニス博士は、レーシックの祖、パリカリシス博士のお弟子と思われる。
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| 以下、Journal of Refractive Surgery Volume22 May 2006 より |
| Late Bilateral Keratectasia After Lasik in a Low Myopia Patient |
To the Edltor:
I read with great interest the article by Lifshitz et al,(*1) which appeared
in the September / October 2005 issue of the Journal of Refractive Surgery,
about late bilateral keratectasia after LASIK in a low myopic patient. There
arel however, several points of criticism in this article.
The authors state that the patient has low myopia "without preoperative
astigmatism" but in the case report they mention that ''central keratometry
measured 44.0@1/46.0@91 in the right eye and 44.50@0/45.50@90 in the
left eye...preoperative corneal topography was within normal limits.”
Although this could happen, the patient has preoperative keratometric
astigmatism of 2.0 diopters (D) and 1.0 D in the right and left eyes,respectively.
To substantiate their findings, preoperative corneal topographies should
have been included to eliminate any objection regarding the possibility
of subclinical keratoconus.
Another major point of criticism was the estimated residual corneal bed
thickness. The authors calculated the residual corneal bed thickness by
subtracting the predicted flap thickness and calculated ablation depth
from preoperative pachymetry. This calculation is inaccurate, as microkeratomes
have been shown to produce a wide range of flap thickness (from approximately
100 μm to 250 μm, despite the manufacturer's instructions). Intraoperative
pachymetry (after flap lifting) is essential to exclude such surprises.
Therefore, the residual corneal bed thickness cannot be assumed.
Finally, although I found this article interesting, I believe it needs
further critical evaluation. Before stating that "patients with low
myopia undergoing LASIK without preoperative risk factors can develop ectasia,"
the authors Should reserve their conclusions, as this case report has weaknesses
in several crucial points.
REFERENCE
1. Lifshitz T, Levy J, Klemperer I, Levinger S, Late bilateral keratectasia
after LASIK in a low myopia patient. J Refract Surg. 2005;21:494-496
GeorgeD・Kymionis，MD，PhD
Grete，Greece
RePly：
We appreciate Dr Kymionis' comments．However，we disagree with his conclusion
regarding possible weakness in "several crucial points" of our
article.
As originally submitted to the Journal of Refractive Surgery, our case
report included pre- and postoperative corneal topography figures. After
the first revision of the article, the preoperative corneal topography
figure, which had already been examined by the Editor and reviewers, was
not included in the final version because of space limitations. After reviewing
the figure, Dr Kymionis will surely conclude that there is no suspicion
of keratoconus or forme fruste keratoconus(Fig).
Regarding the“wide range of flap thickness（from approximately 100μm to 250μm）” as Dr Kymionis
suggested, a detailed review of the published literature shows that for
the NIDEK MK2000 microkeratome, which we used in our patient, in cases
with a planned flap of 160 μm, the real flap thickness was found to be
thinner-121±20μm(*1), 147.7±21.74μm(*2), or 141.16±20.11μm in the
right eye and 120.95±26.95μm in the left eye(*3)-with these thicknesses
far from the 250μm that Dr Kymionis suggests.
As recently published in the Journal of Refractive Surgery by a committee
of seven refractive surgeons(*4), "ectasia can develop in eyes with
no currently identifiable risk factors"; ectasia can also develop
in patients with low myopia and without preoerative risk factors, as we
stated.
REFERENCES
1. Solomon KD, Donnenfeld E, Sandoval HP, Al Sarraf O, Kasper TJ, Holzer
MP, Slate EH, Vroman DT. Flap Thickness Study Group. Flap thickness accuracy:
comparison of 6 microkeratome models. J Cataract Refract Surg. 2004;30:964-977.
2. Arbelaez MC．Nidek MK2000 microkeratome clinical evaluation.′J Refract
Surg. 2002；18：S357-S360．
3. Shemesh G, Dotan G，Lipshhitz I, Predictability of corneal flap thickness in laser in situ keratomileusis using three dofferent microkeratomes. J Refract Surg. 2002;18:S347-S351
4. Binder PS, Lindstrom RL, Stulting RD, Donnenfeld E, Wu H, McDonnell
P, Rabinowitz Y. Keratoconus and corneal ectasia after LASIK. J Refract
Surg.2005;21:749-752.
Tova Lifshitz,MD
Jaime Levy,MD
Bee-Sheva,Israel
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