Full-Thickness Macular Hole Formation after Internal Limiting Membrane Peeling: Beware the “Omega Sign”

Purpose. To introduce a clinical sign on spectral domain optical coherence tomography (SDOCT), which may indicate high risk for full-thickness macular hole formation after internal limiting membrane (ILM) peeling.Methods. The preoperative SDOCT images of two patients—one with multilaminar hemorrhage from ruptured retinal artery macroaneurysm and one with serous retinal detachment and severe macular schisis from optic pit maculopathy—who developed full-thickness macular hole (FTMH) after ILM peeling were evaluated retrospectively.Results. On the preoperative SDOCT images of both patients there was a thin bridge of tissue on either side of the foveal center with an outer retinal defect. The photoreceptors were displaced laterally away from the foveal center to create an “omega-” shaped configuration of the remaining tissue.Conclusion. “Omega-” shaped configuration on SDOCT may represent a higher risk of FTMH following ILM peeling. Vitreoretinal surgeons may wish to consider this sign in the process of their surgical decision making.

Asymptotic estimates for localized electromagnetic modes in doubly periodic structures with defects

The paper presents analytical and numerical models describing localized electromagnetic defect modes in a doubly periodic structure involving closely located inclusions of elliptical and circular shapes. Two types of localized modes are considered: (i) an axi-symmetric mode for the case of transverse electric polarization with an array of metallic inclusions; (ii) a dipole type localized mode that occurs in problems of waveguide modes confined in a defect region of an array of cylindrical fibres, and propagating perpendicular to the plane of the array. A thin bridge asymptotic analysis is used for case (i) to establish double-sided bounds for the frequencies of localized modes in macro-cells with thin bridges. For the case (ii), the electric and magnetic fields independently satisfy Helmholtz equations, but are coupled through the boundary conditions. We show that the model problem associated with localized vibration modes is the Dirichlet problem for the Helmholtz operator. We characterize defect modes by introducing a parameter called the ‘effective diameter’. We show that for circular inclusions in silica matrix, the effective diameter is accurately represented by a linear function of the inclusion radius.

Combined Heermann and Tos (CHAT) technique in cholesteatoma surgery: surgical technique and preliminary results

The combined Heermann and Tos (CHAT) technique is the combination of Heermann’s ’cartilage palisade tympanoplasty’ and Tos’s ’modified combined approach tympanoplasty = modified intact canal wall mastoidectomy’. The first author (Cem Uzun) performed the CHAT technique as a one-stage operation in 15 ears of 15 patients with cholesteatoma. Two patients (one with a follow up of less than six months and one who did not show up at the final re-evaluation) were excluded from the study. Median age in the remaining 13 patients was 37 years (range: 14–57 years). Cholesteatoma type was attic, sinus (Tos tensa type 1) and tensa retraction (Tos tensa type 2) in six, five and two ears, respectively. Cholesteatoma stage was Saleh and Mills stage 1, 2, 3, 4 and 5 in one, three, four, four and one ear, respectively. The eustachian tube was not involved with cholesteatoma in any ear. After drilling of the superoposterior bony annulus, transcanal atticotomy with preservation of thin bridge and cortical mastoidectomy with intact canal wall, the cholesteatoma was removed, and the eardrum and atticotomy were reconstructed with palisades of auricular cartilage. Type I tympanoplasty was performed in two ears, type II in nine ears and type III (stapes absent) in two ears, with either autologous incus (eight cases), cortical bone (two) or auricular cartilage (one). No complication occurred before, during or after surgery. Oto-microscopy and audiometry were done before and at a median of 13 months after surgery (mean 14 months, range 7–30 months). There was no sign of residual or recurrent cholesteatoma in any patient during the follow-up period. At the final examination, all ears were dry and had an intact eardrum except one with a small, central hole, which had been seen since the early post-operative period. Clean and stable attic retraction with a wide access was observed in two ears. Post-operative hearing at the final evaluation was better (change > 10 dB) than the pre-operative one in nine ears and did not change in the remaining four. Pre- and post-operative mean hearing values were, pure-tone average 47 and 35 dB (p = 0.01) and air-bone gap 30 and 20 dB (p = 0.02), respectively. With the CHAT technique, cholesteatoma can be completely and safely removed from the middle ear, and a durable and resistant reconstruction of the middle ear with reasonable hearing can be achieved. However, a further study should analyse long-term results of a larger patient group.