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PURPOSE: To compare postoperative corneal nerve fiber regeneration after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK). METHODS: The medical records of patients who underwent SMILE were retrospectively reviewed. Patients with SMILE in one eye (the SMILE group) and FS-LASIK in the fellow eye (the FS-LASIK group) and who had undergone a confocal microscopy study were retrospectively identified. Subbasal nerve fiber density was measured and compared between the groups preoperatively and at 1 week and 1, 3, and 6 months postoperatively. RESULTS: Thirty eyes of 15 patients were included in the study. Preoperative characteristics of the eyes were similar between the groups. However, there was a statistically significant difference in subbasal nerve fiber density between the groups at 1 month (SMILE group: 1,505 ± 627 µm/mm(2) [range: 625 to 2,540 µm/mm(2)], FS-LASIK group: 1,107 ± 509 µm/mm(2) [range: 595 to 2,313 µm/mm(2)], P = .003) and 3 months (SMILE group: 1,534 ± 503 µm/mm(2) [range: 650 to 2,255 µm/mm(2)], FS-LASIK group: 1,194 ± 485 µm/mm(2) [range: 530 to 1,695 µm/mm(2)], P = .004) postoperatively. No statistically significant difference was detected at 1 week and 6 months postoperatively. CONCLUSION: Eyes treated with SMILE have a higher density of subbasal nerve fibers than eyes treated with FS-LASIK in the early postoperative period (1 week to 3 months) but the two procedures are equivalent by 6 months postoperatively.

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PURPOSE: To evaluate the vision-related quality of life (QoL) of glaucoma patients in terms of the correlation between visual field (VF) loss and National Eye Institute Visual Functioning Questionnaire-39 (NEI VFQ-39) survey. MATERIALS AND METHODS: A total of 244 glaucoma patients were examined with monocular Humphrey 24-2 central full threshold and Esterman binocular VF tests. Patients were grouped according to their monocular VFs done by Advanced Glaucoma Intervention Study (AGIS) classification and Esterman binocular VF efficiency scores. NEI VFQ-39 was applied for the evaluation of vision-related QoL. RESULTS: NEI VFQ-39 subscales and total scores were evaluated and the highest mean average values were in "color vision" (92.00±16.59) and "social functioning" (90.74±15.98). The lowest mean average values were in "general health" (54.76±18.86) and "general vision" (66.03±17.59). All the subscales except "general health" and "ocular pain" showed positive correlations with the monocular and Esterman binocular VF groupings. Pearson correlation analysis between NEI VFQ-39 subscales and the AGIS VF classification-based groups indicated that the subscales had statistically significant negative correlations except the "general health" (r=-0.151, P=0.018) and "ocular pain" (r=-0.048, P=0.455). The highest correlation with AGIS VF classification was in "driving" (r=-0.477, P=0.001) and "general vision" (r=-0.446, P=0.000) subscales. There was statistically significant correlation between NEI VFQ-39 subscales and Esterman binocular VF groups except "general health" (r=-0.064, P=0.318) and "ocular pain" (r=-0.062, P=0.337). The highest negative correlation was in "distant activities" (r=-0.522, P=0.000) and the lowest negative correlation was in "color vision" (r=-0.416, P=0.000) subscales. The highest correlation between binocular distant and binocular near-visual acuities was in "distant activities" and the lowest correlation was in "role difficulties" subscales. CONCLUSIONS: There is statistically significant correlation between the glaucoma patients' VF loss and the vision-related QoL. The evaluation of self-reported vision status in glaucoma patients may be a guide for the rehabilitation of their disabilities in vision-related daily activities.

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PURPOSE: To compare the efficacy, safety and postoperative pain of mechanical versus transepithelial photorefractive keratectomy (PRK) techniques. SETTING: Cornea and refractive surgery subspecialty. DESIGN: Prospective clinical trial. METHODS: This prospective comparative study included 84 eyes of 42 patients with myopia who received mechanical PRK (m-PRK) in 1 eye and transepithelial PRK (t-PRK) in the contralateral eye. The mean patient age was 28.5±6.3 years (range 20-46 years). Postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refractions, postoperative epithelial healing time, surgical time, postoperative pain rating and corneal haze were recorded. RESULTS: At week 1, statistically the UDVA was significantly better in the t-PRK eyes; however, at 3 months, similar refractive stability was achieved in both groups. The mean spherical equivalent (SE) decreased from -2.44±1.00D (m-PRK eyes) and -2.88±1.24D (t-PRK eyes) at baseline to -0.19±0.38D and -0.30±0.40D, respectively, after 1 year. Surgical time was 98.6±9.8s in m-PRK eyes and 58.0±6.4s in t-PRK eyes. On postoperative days 1 and 3, using the global assessment rating, 81% of mPRK eyes that had pain, reported more pain than that reported for the tPRK eyes. In addition, m-PRK treated eyes demonstrated higher mean pain scores based on the 11-point numerical rating scale and Visual Analogue Scale (VAS). The mean time to complete epithelial healing was 2.19±0.39 days (t-PRK) and 3.76±0.43 days (m-PRK). CONCLUSION: t-PRK for mild-to-moderate myopia was more comfortable than conventional m-PRK; patients had less pain, and faster healing time.

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PURPOSE: To compare postoperative visual acuity and higher-order aberrations (HOAs) after femtosecond lenticule extraction (FLEX) and after small-incision lenticule extraction (SMILE). METHODS: Medical records of refractive lenticule extraction patients were retrospectively reviewed. Twenty patients were treated with FLEX. A comparable group of 20 SMILE patients were retrospectively identified. Only one eye of each patient was randomly chosen for the study. Visual acuity, subjective manifest refraction and corneal topography before and 6 months after the surgery were analyzed for both groups. Total HOAs, spherical aberrations, coma and trefoil were calculated from topography data over the 4- and 6-mm-diameter central corneal zone. RESULTS: The mean preoperative SE was -4.03 ± 1.61 in the SMILE group and -4.46 ± 1.61 in the FLEX group. One year after surgery, the mean SE was -0.33 ± 0.25 in the SMILE group and -0.31 ± 0.41 in the FLEX group (p=0.86). In the SMILE group a greater number of eyes were within ±0.50D of the target refraction (95% versus 75%); however, the difference was not statistically significant (p=0.18). Furthermore, 80% of FLEX eyes and 95% of SMILE eyes had an uncorrected distance visual acuity of 20/25 or better (p=0.34). Total HOAs, spherical aberration, coma and trefoil increased postoperatively in both groups. However, there was no statistically significant difference between the groups preoperatively and postoperatively. CONCLUSION: FLEX and SMILE result in comparable refractive results. In addition, corneal aberrations induced by different techniques of lenticule extraction seemed similar to each other.

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We use fine-detuning of pump wavelengths to adjust the tap phases in a complex-coefficient optical tapped-delay-line that utilizes conversion/dispersion-based delays and nonlinear wave mixing. Full 2π phase tuning is demonstrated by detuning the frequency of laser pumps by <20 GHz, which shows close agreement with theory.

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PURPOSE: To evaluate the success rate of 980 nm transcanalicular diode laser-assisted dacryocystorhinostomy (TDL-DCR) in patients with primary acquired nasolacrimal duct obstruction (PANDO) and to consider the time and the reasons of failure. METHODS: Hundred and thirty eyes of 125 patients who underwent of TDL-DCR for the treatment of PANDO are included in this retrospective, noncomparative, nonrandomized, interventional study. The mean follow-up time was 24.29 months (range 8-34 months). Functional success was described as disappearance of epiphora and presence of a patent ostium on lacrimal irrigation. Anatomical success was described as a patent ostium to irrigation but continuing epiphora. Patients with persistent epiphora and a closed ostium were classified as a surgical failure. RESULTS: At third month follow up, 85.4% of cases had complete resolution of their symptoms. The functional success rate decreased to 67.7% at 6 months, to 63.3% at first year, and to 60.3% at second year, while the patency of the lacrimal drainage system was restored in 93.1%, 74.6%, 69.5%, and 68.2% of the cases, respectively. The average total amount of delivered laser energy was 1322.7 J. No correlation could be found between the age of the patient, delivered laser energy, and the surgical success (p = 0.38, p = 0.62). CONCLUSIONS: Transcanalicular diode laser-assisted DCR is a fast and relatively easy alternative surgical method, which avoids a facial skin scar, to treat PANDO. The functional success rate is higher in the first months but decreases to low 60 %'s at the end of first year and remains the same at the second-year follow up.

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PURPOSE: To evaluate the effect on ocular alignment of Y splitting the lateral rectus muscle and then reattaching the 2 ends near the medial rectus muscle insertion in patients with complete oculomotor nerve palsy. METHODS: All eyes with oculomotor nerve palsy treated between May 2008 and February 2010 with Y splitting and transposition of the lateral rectus muscle to the medial rectus muscle were prospectively studied. In this procedure, the lateral rectus muscle was split: the upper half was transposed to the superior border and the lower half to the inferior border of the medial rectus insertion. For the muscles that had lost the ability to stretch and strain due to fibrosis, a hang-back technique was used. In some patients, the medial rectus muscle of the same eye was subsequently strengthened or the lateral rectus muscle of the fellow eye was recessed. Final deviation from 0(Δ) to 10(Δ) was considered a successful result. RESULTS: A total of 10 patients were included. Patients had a preoperative horizontal deviation >45(Δ) (range, 45(Δ)-90(Δ)). Of the 10 patients, 5 attained stable results following surgery, and 5 with postoperative undercorrection between 20(Δ) and 30(Δ) required further surgeries. Postoperatively, 2 patients improved their sensorial status in a very limited range of gaze and 2 patients had symptomatic diplopia. CONCLUSIONS: Acceptable aesthetic results can be achieved in the treatment of complete oculomotor nerve palsy with the transposition of the split lateral rectus muscle to the medial rectus muscle area.

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We experimentally demonstrate a reconfigurable optical converter/encoder for quadrature amplitude modulated (QAM) signals. The system utilizes nonlinear wavelength multicasting, conversion-dispersion delays, and simultaneous nonlinear multiplexing and sampling. We show baud rate tunability (31 and 20 Gbaud) and reconfigurable conversions from lower-order QAM signals to higher-order QAM signals (e.g., 64-QAM).

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We experimentally demonstrate a reconfigurable optical tapped delay line in conjunction with coherent detection to search multiple patterns among quadrature phase shift keying (QPSK) symbols in 20 Gbaud data channel and also to equalize 20 and 31 Gbaud QPSK, 20 Gbaud 8 phase shift keying (PSK), and 16 QAM signals. Multiple patterns are searched successfully on QPSK signals, and correlation peaks are obtained at the matched patterns. QPSK, 8 PSK, and 16 QAM signals are also successfully recovered after 25 km of SMF-28 with average EVMs of 8.3%, 8.9%, and 7.8%. A penalty of <1 dB optical signal to noise penalty is achieved for a 20 Gbaud QPSK signal distorted by up to 400 ps/nm dispersion.

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We experimentally demonstrate a tunable and reconfigurable optical discrete Fourier transform (DFT) to demultiplex orthogonal-frequency-division-multiplexed subcarriers with 2/3/4 subcarriers at 20/40 GHz frequency spacing. An average power penalty of ~5 dB (~3.5) at bit error ratio of 10(-9) is achieved for 4×20 Gbit/s (4×10 Gbit/s) OFDM signal with 20 GHz frequency spacing.

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We demonstrate optical true time delays using wavelength conversion coupled with chromatic dispersion. The transfer function of the delay system is investigated, and it is shown that 3-dB bandwidth of the system can be increased over 40 GHz by using offset pumps. A flat magnitude response (<1 dB peak-peak, 0.2 dB RMS deviation) is achieved in the 1-30 GHz band. Calculated matched filter output to LFM pulses shows good performance, maintaining a > 30 dB peak-to-sidelobe-ratio. The effect of pump depletion during wavelength conversion is also investigated.

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We propose and experimentally demonstrate ultrawideband monocycle pulse generation using nondegenerate two-photon absorption in a silicon waveguide. The free-carrier absorption induced pulse tail at the rising edge of inverted probe pulse is largely compensated by the overlapped pump pulse and results in a symmetric negative monocycle pulse. A 143 ps Gaussian monocycle pulse is successfully obtained with a 131.7% fractional 10 dB bandwidth using a 68 ps pulsed pump. The 10 dB bandwidth and center frequency of the RF spectrum for the generated monocycle pulse can be largely tuned using an optical delay line. An operational bandwidth of 30 nm is demonstrated experimentally with stable performance, and larger optical bandwidth is expected.

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We experimentally characterize the performance of a continuously tunable all-optical complex-coefficient finite-impulse-response (FIR) filter that exploits nonlinear signal processing (multiplexing and multicasting) and conversion-dispersion-based optical delays. Various length (three and four) optical FIR filters with different tap amplitudes (from 0 to -9 dB), tap phases (from 0 to 2π), and tap delays (~37.4 ps and 25 ps) are realized, showing reconfiguration and tuning capabilities of this FIR filter. The measured frequency responses show close agreement with the theoretical filter responses.

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PURPOSE: The purpose of this study was to define the morphologic differences in idiopathic and secondary epiretinal membranes (ERMs) using a time domain optical coherence tomography. METHODS: The medical records and optical coherence tomography images of 293 eyes of 236 consecutive patients diagnosed to have ERM were evaluated retrospectively. Demographic features, best-corrected visual acuities, central macular thickness, membrane attachment patterns, macular changes, and the presence of posterior retinal detachment at the time of diagnosis were compared between the groups (idiopathic group, n = 125 eyes; secondary group, n = 168 eyes). RESULTS: The mean age was higher among idiopathic ERMs (67 ± 9 vs. 62 ± 10 years, P = 0.001). In the secondary group, best-corrected visual acuity was estimated to be worse (P < 0.001) and central macular thickness higher (P = 0.02) than the idiopathic group. In both groups, ERMs were mostly diagnosed at Grade 1 level. Diffuse attachment was more common in both of the groups. Among macular changes, only cystoid macular degeneration differed significantly between the groups (P = 0.0001). CONCLUSION: Idiopathic and secondary ERMs were estimated to differ significantly at the time of diagnosis in terms of age, visual acuities, macular thickness, presence of cystoid macular degeneration, and posterior vitreous detachment. These parameters may assist the retinal surgeon in the treatment process of ERM.

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PURPOSE: To evaluate the long-term visual results of Acufocus ACI-7000 (now Kamra) intracorneal inlay implantation in presbyopic phakic patients. SETTING: Beyoglu Eye Training and Research Hospital, Istanbul, Turkey. DESIGN: Clinical trial. METHODS: This study comprised patients with emmetropic or post-laser in situ keratomileusis (LASIK) presbyopia. Patients had an uncorrected near visual acuity (UNVA) of 20/40 or worse, correctable to 20/25 or better at distance. The inlay was implanted on the stromal bed after the LASIK flap was relifted or a flap created. The inlay was centered on the presurgical position of the first Purkinje reflex. The main outcome measures were distance and near vision and the complication rate. RESULTS: The study enrolled 39 patients aged 45 to 60 years. At the 4-year follow-up, all patients (N = 22) had 2 or more lines of improvement in UNVA with no significant loss in distance vision. The mean final UNVA was 20/20 (Jaeger [J1]); 96% of patients could read J3 or better. The uncorrected distance acuity was 20/40 or better in all eyes. Five patients had cataract progression, and 2 had a change in refractive status. No eye with an intracorneal inlay had intraoperative complications during cataract extraction. Four inlays were explanted during the study. There were no severe corneal complications that affected final vision. CONCLUSION: Intracorneal inlay implantation was an effective, safe, and reversible procedure for the long-term surgical treatment of presbyopia.

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We propose and demonstrate data exchange in both the wavelength and time domains at a fine granularity, i.e., low-speed tributary channel exchange of wavelength-division multiplexed high-speed optical time-division multiplexed signals. Using the parametric depletion effect of cascaded second-order nonlinear interactions in a periodically poled lithium niobate (PPLN) waveguide, we experimentally implement 10 Gbit/s tributary channel exchange between two 160 Gbit/s signals with a power penalty of less than 4 dB at a bit-error rate of 10(-9). Moreover, taking into account the waveguide propagation loss, we derive analytical solutions to investigate the signal depletion (SD) and extinction ratio (ER) performance of the PPLN-based data exchange. The theoretical analyses indicate that low waveguide propagation loss benefits large achievable SD and ER.

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We demonstrate a method to use phase-modulated pumps for multicasting of return-to-zero differential phase-shift keying (RZ-DPSK) signals. The method uses phase modulation of the input signal along with the co-phase-modulated pumps prior to wavelength conversion. Nine copies of a 50 Gbit/s RZ-DPSK data signal are generated via four-wave mixing with an average conversion efficiency of ∼0 dB. An average receiver sensitivity penalty of ∼1.9 dB is observed at a bit-error rate of 10(-9) with a worst case of 2.3 dB. The effects of synchronization errors and phase-modulation frequencies up to 5 GHz are investigated.

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A frequency-sweep-free method for distributed Brillouin sensing is proposed, having the potential for fast dynamic strain measurements. In this reported implementation of the method, multiple probe waves with carefully chosen optical frequencies simultaneously propagate in the fiber against an equal number of sequentially-launched, short pump pulses of matching frequencies, where each of pump-probe pair replaces one sweeping step in the classical BOTDA technique. Experimentally, distributed sensing is demonstrated with a spatial resolution of a few meters.

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OBJECTIVE: To analyze the visual results of phacoemulsification in highly myopic eyes, to investigate the risk factors for poor postoperative visual acuity and to assess postoperative complications. METHODS: This retrospective study reviewed the records of 209 eyes of 150 patients with high myopia who underwent phacoemulsification and foldable intraocular lens (IOL) implantation between January 1998 and July 2008 at Beyoglu Education and Research Eye Hospital, Istanbul, Turkey. RESULTS: Postoperative best-corrected visual acuity (BCVA) was 0.5 or better in 63.2% of eyes. One hundred forty-seven (70.3%) eyes were within ±1.0 diopter (D) of the intended target refraction. In multiple regressions, only pre-existing myopic chorioretinal macular degeneration was found to be associated with poor BCVA (p=0.000). Nor patient age nor axial length (AL) had any correlation with postoperative BCVA. Retinal detachment (RD) occurred in one eye (0.5%) during mean follow-up (18.7+/-8.9 months). CONCLUSION: Most of the eyes with high myopia achieved satisfactory improvement in BCVA with few complications. Myopic retinal degenerative changes were the single independent factor limiting visual potential. Our lower incidence of postoperative RD could be attributed partially to our lower neodymium:yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy rates and our surgical modification involving the implementation of primary posterior capsulorhexis in all patients younger than 40.

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We report the phase-transparent optical data exchange of differential phase-shift keying (DPSK) signals by exploiting the parametric depletion of nondegenerate four-wave mixing (FWM) in a highly nonlinear fiber. Theoretical analyses of nondegenerate FWM involving two signals and two pumps are presented. Analytical solutions are derived, indicating the exchange condition and the feasibility of phase-transparent data exchange. Optical data exchange between 10.7 Gbit/s non-return-to-zero DPSK (NRZ-DPSK) and return-to-zero DPSK signals is implemented with a power penalty of approximately 1.5 dB at a bit-error rate (BER) of 10(-9). Moreover, we demonstrate phase-transparent optical data exchange between two 40 Gbit/s NRZ-DPSK signals with a power penalty of approximately 4.5 dB at a BER of 10(-9).