Retinal Nerve Fiber Layer Thickness Post-Laser Treatment in Diabetic Retinopathy: Argon versus Pattern Scanning Laser
Retinal Nerve Fiber Layer for PASCAL Versus ARGON
Abstract
Conventional argon laser causes transient thickening of retinal nerve fibre layer (RNFL). The effect of pattern scanning laser (PASCAL) has not been well described. We compared the immediate changes in peripapillary RNFL thickness post-panretinal photocoagulation between conventional argon lasers and PASCAL in patients with diabetic retinopathy changes. A total of 32 subjects were recruited. There were 16 patients in the argon group and 16 patients in PASCAL group. Diabetic patients were recruited from Ophthalmology Clinic, Universiti Kebangsaan Malaysia Medical Centre (UKMMC). Complete eye examinations and fundus photographs were performed at baseline prior to laser treatment, and post-laser treatment at two and four months. RNFL thickness was measured using time domain optical coherence tomography. Both groups were comparable with respect to clinical characteristics and demographics. There was no significant difference in average RNFL thickness between the two groups prior to treatment (p= 0.323). RNFL post-laser treatment for patients receiving conventional argon laser remained unchanged with no significant differences in all quadrants at any time-point (two and four months). However, for the PASCAL group, significant thickening occurred at four months for average RNFL and the inferior quadrant (p <0.05). The other quadrants similarly demonstrated increasing thickness at four months but this did not reach statistical significance. Transient RNFL thickening occurs in both conventional and PASCAL laser patients. The PASCAL laser induces a greater increase in RNFL thickness than the argon laser group. Important events, such as laser eye treatments and even type of laser used, are worthy of consideration when evaluating RNFL.
Keywords :
diabetic retinopathy,
optical coherence,
photocoagulation,
retinal ganglion cells,
tomography,
Abstrak
Rawatan konvensional laser argon menyebabkan ketebalan sementara pada lapisan saraf retina (RNFL). Tetapi kesan dari ‘pattern scanning laser’ (PASCAL) tidak banyak diketahui. Kajian ini dilakukan untuk membandingkan kesan selepas konvensional laser argon dibandingkan dengan PASCAL pada pesakit yag mengalami masalah diabetik retinopati. Sebanyak 32 subjek telah terpilih dalam kajian ini. Seramai 16 pesakit dalam kumpulan argon dan 16 pesakit dalam kumpulan PASCAL. Pesakit yang terlibat diambil dari klinik mata, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM). Pemeriksaan mata yang lengkap dan gambar fundus dilakukan pada awal kajian, selepas 2 bulan dan 4 bulan dilaser. RNFL diukur menggunakan domain masa tomografi koheren optikal (OCT). Kedua kumpulan mempunyai ciri klinikal yang sama sebelum rawatan (p= 0.323). RNFL selepas laser argon tidak berubah secara signifikan dalam semua kuadran pada bulan ke 2 dan 4 selepas rawatan. Namun, untuk kumpulan PASCAL, perubahan sigifikan telah ditemui pada bulan ke 4 rawatan pada ‘average RNFL’ dan RNFL ‘inferior’ (p<0.05). Bahagian lain menunjukkan kenaikan ketebalan RNFL tetapi tidak signifikan secara statistik. Sebagai kesimpulan, kenaikan RNFL berlaku pada kedua-dua kumpulan. Pesakit PASCAL mengalami lebih ketebalan. Dengan itu, adalah perlu mengambil kira kejadian laser yang baru berlaku jika mahu menganalisa ketebalan RNFL.
Kata Kunci :
fotokoagulasi,
optikal koheren tomografi,
retinopati diabetes,
sel retinal gaanglion,
tomografi,
Correspondance Address
Mushawiahti Mustapha, Department of Ophthalmology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur, Malaysia. Tel: +60391455981 Fax: +60391456673 E-mail: drmusha@yahoo.com/drmusha@gmail.com
