Optical Coherence Tomography in Gas-filled Eyes

We studied 26 eyes with an idiopathic macular hole (MH), 7 eyes with a MH retinal detachment (MHRD), and 4 eyes with a MH with myopic traction maculopathy. This was a prospective study conducted between April 2009 and August 2009 at the Kyorin Eye Center of the Kyorin University School of Medicine, Tokyo, Japan. The age, gender, laterality of the diseased eye, stage of MH based on the Gass classification, and Snellen best-corrected visual acuity (BCVA) were recorded. The axial length was measured with the OA1000 (TOMEY Corp., Nagoya, Japan) preoperatively in eyes with MH and postoperatively in eyes with MHRD and myopic traction maculopathy to avoid the effect of retinal detachment on the axial length. The presence of a posterior staphyloma within the posterior vascular arcade was determined by ophthalmoscopy and ultrasonography (Ultrascan®, Alcon Laboratories, Fort Worth, TX).

Standard pars plana vitrectomy was performed. The internal limiting membrane (ILM) was removed after making it visible with triamcinolone acetonide (Kenacort-A®, Bristol Pharmaceuticals KK, Tokyo, Japan) or indocyanine green (Santen Pharmacy, Osaka, Japan) in all eyes. Preoperative cataracts were graded as mild (nuclear sclerosis 1+) or moderate to advanced (nuclear sclerosis 2+ or 3+), and phacoemulsification with implantation of an intraocular lens was performed on all cataractous eyes higher than grade 1. Room air, 20% sulfur hexafluoride (SF6), or 14% perfluoropropane (C3F8) was used to tamponade the retina. When the MH was confirmed to be closed in the patients with a idiopathic MH, the face-down position was discontinued although the patients were instructed to avoid an upright position. Patients with MHRD and myopic traction maculopathy were instructed to keep a facedown position for one to two weeks even after a MH closure was detected.

All surgery was performed under retrobulbar anesthesia, and a written informed consent was obtained from all patients after a full explanation of the purpose and possible complications of the treatment. The study protocol was approved by the Institutional Review Committee of the Kyorin University School of Medicine and all of the patients approved the clinical review of their medical records.

The entire macular area was scanned by SD-OCT (OCT4000, Cirrus HD-OCT, Carl Zeiss Medic Inc., Dublin, California, USA) in the sitting position to avoid missing a MH. The 5-line raster mode was used to obtain high quality images on postoperative days 1, 3, 7, and 30. When a macular image could not be obtained, the patients were instructed to look slightly downward or upward until a clearer view of the macular area was obtained in the OCT images. The ability to detect a closed MH or the status of the foveal detachment or schisis by the SD-OCT was evaluated, and the pre- and postoperative factors that affected the OCT images were investigated. The volume of intravitreal gas was estimated by the level of the inferior gas meniscus at the retina with an indirect ophthalmoscope in a sitting position.