Yong Eun Lee

Open ring-shaped guider for circular continuous curvilinear capsulorhexis during cataract surgery

&NA; We describe a new type of open‐loop caliper for capsulorhexis during cataract surgery. This tool, which is made of poly(methyl methacrylate), can optimize capsulorhexis shape, size, and centration. One of the strengths of this tool, which derives from the open‐loop design, is its ease of insertion and removal via a small incision site compared with other calipers used for capsulorhexis. The caliper is positioned on the anterior capsule after the anterior chamber is filled with an ophthalmic viscosurgical device and removed after creation of the continuous curvilinear capsulorhexis. The caliper enables the surgeon to achieve an ideal capsulorhexis and promotes long‐lasting circularity. Financial Disclosure Dr. Joo is one of the inventors on the patent filed by the Catholic University of Korea covering details in this manuscript. Dr. Lee has no financial or proprietary interest in any material or method mentioned.

Assessment of Lens Center Using Optical Coherence Tomography, Magnetic Resonance Imaging, and Photographs of the Anterior Segment of the Eye.

PURPOSE To determine the nearest marker for evaluating the center of the crystalline lens using optical coherence tomography (OCT), magnetic resonance imaging (MRI), and photographs. METHODS Optical coherence tomography scans of human eyes were obtained in vivo during femtosecond laser-assisted cataract surgery. From axial and sagittal images, the distance of the angle center (AC) and pupil center (PC) from the scanned capsule center (SCC) was calculated. From pre- and postoperative photographs, the distance of the PC and limbal center (LC) from the intraocular lens (IOL) center was calculated, and distance between each center on the lens equatorial plane was compared. After combination of pre- and postoperative images, we arranged the centers in order of distance from the IOL center. High-resolution MRI was performed in pig eyes ex vivo to confirm the exact location of the lens center relative to other centers. RESULTS In human OCT scans and photographs (n = 76), the IOL center to AC distance was 0.22 ± 0.13 mm, the IOL center to SCC distance was 0.22 ± 0.12 mm, the IOL center to PC distance was 0.25 ± 0.17 mm, and the IOL center to LC distance was 0.30 ± 0.18 mm. The AC and SCC were significantly closer to the IOL center than the PC or LC. In MRI (n = 54 images), the lens center to AC distance was 0.90 ± 0.58 mm, and the lens center to PC distance was 1.53 ± 0.87 mm (Δ distance = 0.63 ± 0.69 mm, P = 0.000). CONCLUSIONS Optical coherence tomography, MRI, and photographs of the anterior segment revealed that the AC is the nearest marker to the center of the lens equator.

Correlation Between Corneal Button Size and Intraocular Pressure During Femtosecond Laser-Assisted Keratoplasty.

Purpose: To evaluate changes in intraocular pressure (IOP) in recipient and donor eyes during femtosecond laser–assisted keratoplasty (FLAK) and to assess for differences in the diameter of trephinated corneal buttons according to changes in pressure. Materials and Methods: Twenty porcine whole eyes (recipient model) and 20 porcine-corneoscleral rims (donor model) were prepared, and anterior chamber pressures were measured using a fiberoptic sensing device (Opsens, Quebec, Canada) during the femtosecond laser corneal cutting process. To determine the diameter of corneal buttons, 10 porcine whole eyes (recipient model) and 12 corneoscleral rims (donor model) of each baseline IOP were cut with the femtosecond laser programmed to the following pattern: “vertical side cut”; 1200 &mgr;m (depth), 8 mm (diameter). Digital photographs were obtained using microscopy and subsequently analyzed. Results: The IOP (mean ± SD) for the recipient model was 10.2 (±0.9) mm Hg at baseline and ranged from 96.6 (±4.5) to ∼138.4 (±3.8) mm Hg during the corneal cutting process. This shows that the maximum IOP during FLAK increased 13.5 times compared with baseline. In the donor model, the mean pressure elevation from baseline artificial anterior chamber (AAC) pressure to corneal cutting was 15.8 (±5.4) mm Hg. This showed a positive correlation with baseline IOP [correlation coefficient (CC) = 0.827, P = 0.006]. As the baseline IOP in the recipient eye increased, trephinated corneal button size was reduced by up to 3.9% in diameter (CC = −0.945, P = 0.015). In addition, in donor eyes, the diameter was decreased by up to 11.7% as the baseline AAC pressure increased (CC = −0.934, P = 0.006). Conclusions: During the FLAK procedure, the IOP increases in both recipient and donor eyes. The diameter of the trephinated donor and recipient corneal buttons was decreased as the initial baseline IOP increased. Ophthalmic surgeons can determine the AAC pressure based on the baseline IOP in the recipient patient.

Biomedical sensing and imaging for the anterior segment of the eye

Eye is an optical system composed briefly of cornea, lens, and retina. Ophthalmologists can diagnose status of patient’s eye from information provided by optical sensors or images as well as from history taking or physical examinations. Recently, we developed a prototype of optical coherence tomography (OCT) image guided femtosecond laser cataract surgery system. The system combined a swept-source OCT and a femtosecond (fs) laser and afford the 2D and 3D structure information to increase the efficiency and safety of the cataract procedure. The OCT imaging range was extended to achieve the 3D image from the cornea to lens posterior. A prototype of OCT image guided fs laser cataract surgery system. The surgeons can plan the laser illumination range for the nuclear division and segmentation, and monitor the whole cataract surgery procedure using the real time OCT. The surgery system was demonstrated with an extracted pig eye and in vivo rabbit eye to verify the system performance and stability.

Size of Continuous Curvilinear Capsulorhexis for Prevention of PCO

Several systemic and ocular associations have been cited as influencing the development of posterior capsule opacification (PCO). Surgical methods such as the size of CCC, in-the-bag IOL implantation, and sealed capsule irrigation also can influence the formation of PCO.