Tesis

Analisis Biomekanika Kornea Pasca Myopic Lasik dengan Flap Femtosecond Laser

Tujuan: Membandingkan respon biomekanika komea pasca LASIK dengan flap femtosecond laser pada penderita miopia serta menilai korelasi faktor-faktor yang mempengaruhi biomekanika kornea. Metode: Sebanyak 60 mata penderita miopia, yang dilibatkan dalam suatu uji klinis kohort prospektif melalui consecutive sampling, menjalani tindakan LASIK dengan flap femtosecond laser (120 pm, IntraLase® FS) dan fotoablasi dengan Allegretto Wave® Eye-Q di Jakarta Eye Centre. Subjek dibagi menjadi kelompok miopia ringan-sedang (SE < 6 D) dan miopia tinggi (SE > 6 D). Analisa data juga dilakukan berdasarkan kelompok miopia komea (keratometri > 44,5 D), miopia aksial (panjang bola mata > 24,5 mm), dan miopia campuran (keratometri > 44,5 D dan panjang bola mata > 24,5 mm). Penilaian respon biomekanika komea dilakukan berdasarkan perubahan topografi komea pada ring 7 {Allegro Wave® Topolyzer) dan atau kedalaman bilik mata depan pada hari pertama pasca LASIK. Hasil: Semua subjek mengalami perubahan topografi komea pasca LASIK berupa flattening pada ring 3 dan steepening pada ring 7 {hyperopic shift). Hyperopic shift didapatkan lebih besar pada kelompok miopia tinggi dan miopia campuran dibandingkan kelompok lain (p < 0,001). Tidak didapatkan perubahan kedalaman bilik mata depan antar kelompok, baik berdasarkan gradasi (p = 0,188) maupun etiologi miopia (p = 0,546). Miopia tinggi (70 %), miopia aksial (77,4 %), dan miopia campuran (76,5 %) menghasilkan target piano yang lebih rendah dibandingkan miopia ringan-sedang (90 %) dan miopia komea (91,7 %). Tingkatan miopia berkorelasi negatif dengan respon biomekanika komea (r = -0,568, p < 0,001). Faktor-faktor yang berkorelasi dengan respon biomekanika kornea adalah besarnya flattening pada ring 3 (r = -0,721, p < 0,001), kedalaman ablasi (r = -0,627, p < 0,001), dan ketebalan residual stromal bed (r = -0,487, p < 0,001). Analisa ancova multivariat mendapatkan flattening pada ring 3 secara signifikan (p < 0,001) berkorelasi positif dengan respon biomekanika komea, yaitu pada miopia ringan-sedang jenis miopia komea (r = 0,766, p = 0,004) dan miopia tinggi jenis miopia aksial (r = 0,765, p < 0,001). Kesimpulan: Penderita miopia ringan-sedang jenis miopia komea dan penderita miopia tinggi jenis miopia aksial berkorelasi kuat dengan respon biomekanika komea yang akan mempengaruhi hasil akhir prediktibilitas pula. Oleh sebab itu, perlu penyesuaian nomogram bukan hanya berdasarkan gradasi miopia, namun juga berdasarkan etiologi miopia sehingga dicapai hasil akhir yang optimal.


Purpose: To compare the corneal biomechanical response of myopic patients after LASIK using femtosecond laser for creation of the corneal flap and to evaluate the correlation between factors which influence corneal biomechanics. Methods: A prospective, cohort, consecutive sampling of 60 eyes (38 myopic patients) undergoing LASIK using a femtosecond laser flap creation (120 pm, IntraLase® FS) and fotoablation using Allegretto Wave® Eye-Q were conducted in Jakarta Eye Centre. Subjects were divided into mild-moderate myopia (SE < 6 D) and high myopia (SE > 6 D). The data were also analyzed based on corneal myopia (keratometry > 44.5 D), axial myopia (axial length > 24.5 mm), and mixed myopia (keratometry > 44.5 D and axial length > 24.5 mm). Parameters of corneal biomechanical response were corneal topographic changes at ring 7 (Allegro Wave® Topolyzer) and or changes of the anterior chamber depth on day 1 after surgery. Results: All subjects showed corneal topographic changes, which were flattening at ring 3 and steepening at ring 7 (hyperopic shift,). Hyperopic shift was greater in high myopia and mixed myopia groups compared to other groups (p < 0.001). No anterior chamber depth changes were reported between groups, neither based on its level (p = 0.188) nor etiology of myopia (p = 0.546). High myopia (70 %), axial myopia (77.4 %), and mixed myopia (76.5 %) achieved lower piano target than mild-moderate myopia (90 %) and corneal myopia (91.7 %). The level of myopia was negatively correlated to corneal biomechanical response (r = - 0.568, p < 0.001). Factors which were correlated to corneal biomechanical response were the amount of flattening at ring 3 (r = -0.72f, p < 0.001), depth of ablation (r = -0.627, p < 0.001), and residual stromal bed thickness (r = -0.487, p < 0.001). Ancova multivariate resulted flattening at ring 3 was significantly (p < 0.001) correlated to mild-moderate myopia with a corneal myopic type (r = 0.766, p = 0.004) and to high myopia with an axial myopic type (r = 0.765, p < 0.001). Conclusion: Mild-moderate myopia with a corneal myopic type and high myopia with an axial myopic type correlated well to corneal biomechanical response which could influence the predictability of refraction. Thus, it is important to adjust the nomogram not only based on its level of myopia but also based on the etiology of myopia so that optimal visual outcomes could be achieved.